Molecules

13 pages, 2362 KiB

Open AccessArticle

Response of MCF-7 Breast Cancer Cells Overexpressed with P-Glycoprotein to Apoptotic Induction after Photodynamic Therapy

by Eric Chekwube Aniogo, Blassan P. George and Heidi Abrahamse

Molecules 2021, 26(23), 7412; https://doi.org/10.3390/molecules26237412 - 06 Dec 2021

Cited by 4 | Viewed by 2855

Abstract

Multidrug resistance (MDR) has posed a significant threat to cancer treatment and has led to the emergence of a new therapeutic regime of photodynamic therapy (PDT) to curb the menace. The PDT modality employs a photosensitiser (PS), excited at a specific wavelength of [...] Read more.

Multidrug resistance (MDR) has posed a significant threat to cancer treatment and has led to the emergence of a new therapeutic regime of photodynamic therapy (PDT) to curb the menace. The PDT modality employs a photosensitiser (PS), excited at a specific wavelength of light to kill cancer cells. In the present study, we used a zinc phthalocyanine tetrasulfonic acid PS to mediate the photodynamic killing of MCF-7 cells overexpressed with P-glycoprotein (P-gp) and investigate the response to cell death induction. After photodynamic treatment, MCF-7 cells undergo cell death, and indicators like Annexin V/PI staining, DNA fragmentation, and measurement of apoptotic protein expression were investigated. Results showed increased externalisation of phosphatidylserine protein, measured as a percentage in flow cytometry indicative of apoptotic induction. This expression was significant (p < 0.006) for the untreated control cells, and there was no detection of DNA fragments after a laser fluence of 20 J/cm². In addition, a statistically significant difference (p < 0.05) was seen in caspase 8 activity and Bax protein expression. These findings were indicative of apoptotic induction and thus seem to represent the extrinsic apoptotic pathway. This study shows the role of PDT in the treatment of a resistant phenotype breast cancer. Full article

(This article belongs to the Special Issue Photodynamic Therapy in Cancer Treatment 2021)

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31 pages, 6131 KiB

Open AccessReview

The Development of BTK Inhibitors: A Five-Year Update

by Bruno Tasso, Andrea Spallarossa, Eleonora Russo and Chiara Brullo

Molecules 2021, 26(23), 7411; https://doi.org/10.3390/molecules26237411 - 06 Dec 2021

Cited by 33 | Viewed by 6029

Abstract

Bruton’s tyrosine kinase (BTK) represented, in the past ten years, an important target for the development of new therapeutic agents that could be useful for cancer and autoimmune disorders. To date, five compounds, able to block BTK in an irreversible manner, have been [...] Read more.

Bruton’s tyrosine kinase (BTK) represented, in the past ten years, an important target for the development of new therapeutic agents that could be useful for cancer and autoimmune disorders. To date, five compounds, able to block BTK in an irreversible manner, have been launched in the market, whereas many reversible BTK inhibitors (BTKIs), with reduced side effects that are more useful for long-term administration in autoimmune disorders, are under clinical investigation. Despite the presence in the literature of many articles and reviews, studies on BTK function and BTKIs are of great interest for pharmaceutical companies as well as academia. This review is focused on compounds that have appeared in the literature from 2017 that are able to block BTK in an irreversible or reversible manner; also, new promising tunable irreversible inhibitors, as well as PROTAC molecules, have been reported. This summary could improve the knowledge of the chemical diversity of BTKIs and provide information for future studies, particularly from the medicinal chemistry point of view. Data reported here are collected from different databases (Scifinder, Web of Science, Scopus, Google Scholar, and Pubmed) using “BTK” and “BTK inhibitors” as keywords. Full article

(This article belongs to the Special Issue Molecules Medicinal Chemistry Reviews)

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15 pages, 4396 KiB

Open AccessArticle

Cinnamon and Eucalyptus Oils Suppress the Inflammation Induced by Lipopolysaccharide In Vivo

by Chen Zhao, Yuwei Cao, Zhuo Zhang, Dechao Nie and Yanling Li

Molecules 2021, 26(23), 7410; https://doi.org/10.3390/molecules26237410 - 06 Dec 2021

Cited by 10 | Viewed by 3436

Abstract

Inflammation caused by bacterial lipopolysaccharide (LPS) disrupts epithelial homeostasis and threatens both human and animal health. Therefore, the discovery and development of new anti-inflammatory drugs is urgently required. Plant-derived essential oils (EOs) have good antioxidant and anti-inflammatory activities. Thus, this study aims to [...] Read more.

Inflammation caused by bacterial lipopolysaccharide (LPS) disrupts epithelial homeostasis and threatens both human and animal health. Therefore, the discovery and development of new anti-inflammatory drugs is urgently required. Plant-derived essential oils (EOs) have good antioxidant and anti-inflammatory activities. Thus, this study aims to screen and evaluate the effects of cinnamon oil and eucalyptus oil on anti-inflammatory activities. The associated evaluation indicators include body weight gain, visceral edema coefficient, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), nitrogen monoxide (NO), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), Urea, Crea, ALT, TLR4, MyD88, NF-κB, IκB-α, iNOS, and Mn-SOD. In addition, tissue injury was determined by H&E staining. The results revealed that cinnamon oil and eucalyptus oil suppressed inflammation by decreasing SOD, TNF-α, and NF-κB levels. We also found that cinnamon oil increased the level of GSH-Px, MDA, and Mn-SOD, as well as the visceral edema coefficient of the kidney and liver. Altogether, these findings illustrated that cinnamon oil and eucalyptus oil exhibited wide antioxidant and anti-inflammatory activities against LPS-induced inflammation. Full article

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16 pages, 15708 KiB

Open AccessArticle

Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins

by Iva Šikuten, Petra Štambuk, Jasminka Karoglan Kontić, Edi Maletić, Ivana Tomaz and Darko Preiner

Molecules 2021, 26(23), 7409; https://doi.org/10.3390/molecules26237409 - 06 Dec 2021

Cited by 15 | Viewed by 2912

Abstract

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: [...] Read more.

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples. Full article

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22 pages, 3392 KiB

Open AccessArticle

Exploiting the Chiral Ligands of Bis(imidazolinyl)- and Bis(oxazolinyl)thiophenes—Synthesis and Application in Cu-Catalyzed Friedel–Crafts Asymmetric Alkylation

by Mohammad Shahidul Islam, Abdullah Saleh Alammari, Assem Barakat, Saeed Alshahrani, Matti Haukka and Abdullah Mohammed Al-Majid

Molecules 2021, 26(23), 7408; https://doi.org/10.3390/molecules26237408 - 06 Dec 2021

Cited by 5 | Viewed by 3869

Abstract

Five new C₂-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent [...] Read more.

Five new C₂-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The utility of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subsequently, the optimized tridentate ligand L5 and Cu(OTf)₂ catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation. Full article

(This article belongs to the Special Issue Chemistry of Indoles)

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17 pages, 763 KiB

Open AccessReview

Anticancer Properties of Eugenol: A Review

by Ali T. Zari, Talal A. Zari and Khalid Rehman Hakeem

Molecules 2021, 26(23), 7407; https://doi.org/10.3390/molecules26237407 - 06 Dec 2021

Cited by 56 | Viewed by 7568

Abstract

Conventional cancer treatments have shown several unfavourable adverse effects, as well as an increase in anticancer drug resistance, which worsens the impending cancer therapy. Thus, the emphasis is currently en route for natural products. There is currently great interest in the natural bioactive [...] Read more.

Conventional cancer treatments have shown several unfavourable adverse effects, as well as an increase in anticancer drug resistance, which worsens the impending cancer therapy. Thus, the emphasis is currently en route for natural products. There is currently great interest in the natural bioactive components from medicinal plants possessing anticancer characteristics. For example, clove (Syzygium aromaticum L.) (Family Myrtaceae) is a highly prized spice that has been historically utilized as a food preservative and for diverse medical uses. It is reckoned amongst the valued sources of phenolics. It is indigenous to Indonesia but currently is cultivated in various places of the world. Among diverse active components, eugenol, the principal active component of S. aromaticum, has optimistic properties comprising antioxidant, anti-inflammatory, and anticancer actions. Eugenol (4-allyl-2-methoxyphenol) is a musky oil that is mainly obtained from clove. It has long been utilized all over the world as a result of its broad properties like antioxidant, anticancer, anti-inflammatory, and antimicrobial activities. Eugenol continues to pique investigators’ interest because of its multidirectional activities, which suggests it could be used in medications to treat different ailments. Anticancer effects of eugenol are accomplished by various mechanisms like inducing cell death, cell cycle arrest, inhibition of migration, metastasis, and angiogenesis on several cancer cell lines. Besides, eugenol might be utilized as an adjunct remedy for patients who are treated with conventional chemotherapy. This combination leads to a boosted effectiveness with decreased toxicity. The present review focuses on the anticancer properties of eugenol to treat several cancer types and their possible mechanisms. Full article

(This article belongs to the Special Issue Preventive and Therapeutic Effects of Plant Bioactive Compounds in Chronic Inflammation and Cancer)

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24 pages, 1066 KiB

Open AccessReview

Deep Eutectic Solvents as Promising Green Solvents in Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplet: Recent Applications, Challenges and Future Perspectives

by Asmaa Kamal El-Deen and Kuniyoshi Shimizu

Molecules 2021, 26(23), 7406; https://doi.org/10.3390/molecules26237406 - 06 Dec 2021

Cited by 28 | Viewed by 3615

Abstract

Deep eutectic solvents (DESs) have recently attracted attention as a promising green alternative to conventional hazardous solvents by virtue of their simple preparation, low cost, and biodegradability. Even though the application of DESs in analytical chemistry is still in its early stages, the [...] Read more.

Deep eutectic solvents (DESs) have recently attracted attention as a promising green alternative to conventional hazardous solvents by virtue of their simple preparation, low cost, and biodegradability. Even though the application of DESs in analytical chemistry is still in its early stages, the number of publications on this topic is growing. Analytical procedures applying dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFOD) are among the more appealing approaches where DESs have been found to be applicable. Herein, we provide a summary of the articles that are concerned with the application of DESs in the DLLME-SFOD of target analytes from diverse samples to provide up-to-date knowledge in this area. In addition, the major variables influencing enrichment efficiency and the microextraction mechanism are fully investigated and explained. Finally, the challenges and future perspectives of applying DESs in DLLME-SFOD are thoroughly discussed and are critically analyzed. Full article

(This article belongs to the Special Issue Recent Advances and Future Trends in Sample Preparation)

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16 pages, 3147 KiB

Open AccessArticle

Supplementary Far-Red and Blue Lights Influence the Biomass and Phytochemical Profiles of Two Lettuce Cultivars in Plant Factory

by Yamin Li, Linyuan Wu, Haozhao Jiang, Rui He, Shiwei Song, Wei Su and Houcheng Liu

Molecules 2021, 26(23), 7405; https://doi.org/10.3390/molecules26237405 - 06 Dec 2021

Cited by 18 | Viewed by 3077

Abstract

Three different LED spectra (W: White light; WFR: W + far-red light; WB: W + blue light) with similar photosynthetic photon flux density (PPFD) were designed to explore the effects of supplementary far-red and blue lights on leaf color, biomass and phytochemicals of [...] Read more.

Three different LED spectra (W: White light; WFR: W + far-red light; WB: W + blue light) with similar photosynthetic photon flux density (PPFD) were designed to explore the effects of supplementary far-red and blue lights on leaf color, biomass and phytochemicals of two cultivars of red-leaf lettuce (“Yanzhi” and “Red Butter”) in an artificial lighting plant factory. Lettuce plants under WB had redder leaf color and significantly higher contents of pigments, such as chlorophyll a, chlorophyll b, chlorophyll (a + b) and anthocyanins. The accumulation of health-promoting compounds, such as vitamin C, vitamin A, total phenolic compounds, total flavonoids and anthocyanins in the two lettuce cultivars were obviously enhanced by WB. Lettuce under WFR showed remarkable increase in fresh weight and dry weight; meanwhile, significant decreases of pigments, total phenolic compounds, total flavonoids and vitamin C were found. Thus, in the plant factory system, the application of WB can improve the coloration and quality of red leaf lettuce while WFR was encouraged for the purpose of elevating the yield of lettuce. Full article

(This article belongs to the Special Issue Phenolic Composition, Antioxidant Potential and Bioactive Potential of Natural Products)

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12 pages, 415 KiB

Open AccessArticle

A Computational Journey across Nitroxide Radicals: From Structure to Spectroscopic Properties and Beyond

by Vincenzo Barone, Marco Fusè, Sandra Mónica Vieira Pinto and Nicola Tasinato

Molecules 2021, 26(23), 7404; https://doi.org/10.3390/molecules26237404 - 06 Dec 2021

Cited by 5 | Viewed by 2175

Abstract

Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms [...] Read more.

Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest. Full article

(This article belongs to the Special Issue Reactivity and Properties of Radicals and Radical Ions)

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16 pages, 3714 KiB

Open AccessArticle

Study by Optical Spectroscopy of Bismuth Emission in a Nanosecond-Pulsed Discharge Created in Liquid Nitrogen

by Anna V. Nominé, Cédric Noel, Thomas Gries, Alexandre Nominé, Valentin A. Milichko and Thierry Belmonte

Molecules 2021, 26(23), 7403; https://doi.org/10.3390/molecules26237403 - 06 Dec 2021

Cited by 2 | Viewed by 1714

Abstract

Time-resolved optical emission spectroscopy of nanosecond-pulsed discharges ignited in liquid nitrogen between two bismuth electrodes is used to determine the main discharge parameters (electron temperature, electron density and optical thickness). Nineteen lines belonging to the Bi I system and seven to the Bi [...] Read more.

Time-resolved optical emission spectroscopy of nanosecond-pulsed discharges ignited in liquid nitrogen between two bismuth electrodes is used to determine the main discharge parameters (electron temperature, electron density and optical thickness). Nineteen lines belonging to the Bi I system and seven to the Bi II system could be recorded by directly plunging the optical fibre into the liquid in close vicinity to the discharge. The lack of data for the Stark parameters to evaluate the broadening of the Bi I lines was solved by taking advantage of the time-resolved information supported by each line to determine them. The electron density was found to decrease exponentially from 6.5 ± 1.5 × 10¹⁶ cm⁻³ 200 ns after ignition to 1.0 ± 0.5 × 10¹⁶ cm⁻³ after 1050 ns. The electron temperature was found to be 0.35 eV, close to the value given by Saha’s equation. Full article

(This article belongs to the Special Issue Sonoluminescence and Related Plasma Luminescence)

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14 pages, 2525 KiB

Open AccessArticle

From a Well-Defined Organozinc Precursor to Diverse Luminescent Coordination Polymers Based on Zn(II)-Quinolinate Building Units Interconnected by Mixed Ligand Systems

by Katarzyna Sołtys-Brzostek, Kamil Sokołowski, Iwona Justyniak, Michał K. Leszczyński, Natalia Olejnik-Fehér and Janusz Lewiński

Molecules 2021, 26(23), 7402; https://doi.org/10.3390/molecules26237402 - 06 Dec 2021

Cited by 1 | Viewed by 1721

Abstract

Introduction of photoactive building blocks into mixed-ligand coordination polymers appears to be a promising way to produce new advanced luminescent materials. However, rational design and self-assembly of the multi-component supramolecular systems is challenging from both a conceptual and synthetic perspective. Here, we report [...] Read more.

Introduction of photoactive building blocks into mixed-ligand coordination polymers appears to be a promising way to produce new advanced luminescent materials. However, rational design and self-assembly of the multi-component supramolecular systems is challenging from both a conceptual and synthetic perspective. Here, we report exploratory studies that investigate the potential of [Zn(q)₂]₂[tBuZn(OH)]₂ complex (q = deprotonated 8-hydroxyquinoline) as an organozinc precursor as well as a mixed-ligand synthetic strategy for the preparation of new luminescent coordination polymers (CPs). As a result we present three new 2D mixed-ligand Zn(II)-quinolinate coordination polymers which are based on various zinc quinolinate secondary building units interconnected by two different organic linker types, i.e., deprotonated 4,4′-oxybisbenzoic acid (H₂obc) as a flexible dicarboxylate linker and/or selected bipyridines (bipy). Remarkably, using the title organozinc precursors in a combination with H₂obc and 4,4′-bipyridine, a novel molecular zinc quinolinate building unit, [Zn₄(q)₆(bipy)₂(obc)₂], was obtained which self-assembled into a chain-type hydrogen-bonded network. The application of the organometallic precursor allowed for its direct reaction with the selected ligands at ambient temperature, avoiding the use of both solvothermal conditions and additional base reagents. In turn, the reaction involving Zn(NO₃)₂, as a classical inorganic precursor, in a combination with H₂obc and bipy led to a novel 1D coordination polymer [Zn₂(q)₂(NO₃)₂(bipy)]. While the presence of H₂obc was essential for the formation of this coordination polymer, this ditopic linker was not incorporated into the isolated product, which indicates its templating behavior. The reported compounds were characterized by single-crystal and powder X-ray diffraction, elemental analysis as well as UV-Vis and photoluminescence spectroscopy. Full article

(This article belongs to the Special Issue Organometallic Compounds and Their Applications)

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29 pages, 6611 KiB

Open AccessReview

Natural and Synthetic Halogenated Amino Acids—Structural and Bioactive Features in Antimicrobial Peptides and Peptidomimetics

by Mario Mardirossian, Marina Rubini, Mauro F. A. Adamo, Marco Scocchi, Michele Saviano, Alessandro Tossi, Renato Gennaro and Andrea Caporale

Molecules 2021, 26(23), 7401; https://doi.org/10.3390/molecules26237401 - 06 Dec 2021

Cited by 19 | Viewed by 3478

Abstract

The 3D structure and surface characteristics of proteins and peptides are crucial for interactions with receptors or ligands and can be modified to some extent to modulate their biological roles and pharmacological activities. The introduction of halogen atoms on the side-chains of amino [...] Read more.

The 3D structure and surface characteristics of proteins and peptides are crucial for interactions with receptors or ligands and can be modified to some extent to modulate their biological roles and pharmacological activities. The introduction of halogen atoms on the side-chains of amino acids is a powerful tool for effecting this type of tuning, influencing both the physico-chemical and structural properties of the modified polypeptides, helping to first dissect and then rationally modify features that affect their mode of action. This review provides examples of the influence of different types of halogenation in amino acids that replace native residues in proteins and peptides. Examples of synthetic strategies for obtaining halogenated amino acids are also provided, focusing on some representative compounds and their biological effects. The role of halogenation in native and designed antimicrobial peptides (AMPs) and their mimetics is then discussed. These are in the spotlight for the development of new antimicrobial drugs to counter the rise of antibiotic-resistant pathogens. AMPs represent an interesting model to study the role that natural halogenation has on their mode of action and also to understand how artificially halogenated residues can be used to rationally modify and optimize AMPs for pharmaceutical purposes. Full article

(This article belongs to the Special Issue A Themed Issue Dedicated to Professor Victor Hruby)

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9 pages, 1155 KiB

Open AccessArticle

Enhancement of Antibiotic Activity by 1,8-Naphthyridine Derivatives against Multi-Resistant Bacterial Strains

by José B. de Araújo-Neto, Maria M. C. da Silva, Cícera D. de M. Oliveira-Tintino, Iêda M. Begnini, Ricardo A. Rebelo, Luiz E. da Silva, Sandro L. Mireski, Michele C. Nasato, Maria I. L. Krautler, Jaime Ribeiro-Filho, Abolghasem Siyadatpanah, Polrat Wilairatana, Henrique D. M. Coutinho and Saulo R. Tintino

Molecules 2021, 26(23), 7400; https://doi.org/10.3390/molecules26237400 - 06 Dec 2021

Cited by 7 | Viewed by 1911

Abstract

The search for new antibacterial agents has become urgent due to the exponential growth of bacterial resistance to antibiotics. Nitrogen-containing heterocycles such as 1,8-naphthyridine derivatives have been shown to have excellent antimicrobial properties. Therefore, the purpose of this study was to evaluate the [...] Read more.

The search for new antibacterial agents has become urgent due to the exponential growth of bacterial resistance to antibiotics. Nitrogen-containing heterocycles such as 1,8-naphthyridine derivatives have been shown to have excellent antimicrobial properties. Therefore, the purpose of this study was to evaluate the antibacterial and antibiotic-modulating activities of 1,8-naphthyridine derivatives against multi-resistant bacterial strains. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of the following compounds: 7-acetamido-1,8-naphthyridin-4(1H)-one and 3-trifluoromethyl-N-(5-chloro-1,8-naphthyridin-2-yl)-benzenesulfonamide. The antibiotic-modulating activity was analyzed using subinhibitory concentrations (MIC/8) of these compounds in combination with norfloxacin, ofloxacin, and lomefloxacin. Multi-resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were used in both tests. Although the compounds had no direct antibacterial activity (MIC ≥ 1.024 µg/mL), they could decrease the MIC of these fluoroquinolones, indicating synergism was obtained from the association of the compounds. These results suggest the existence of a structure–activity relationship in this group of compounds with regard to the modulation of antibiotic activity. Therefore, we conclude that 1,8-naphthyridine derivatives potentiate the activity of fluoroquinolone antibiotics against multi-resistant bacterial strains, and thereby interesting candidates for the development of drugs against bacterial infections caused by multidrug resistant strains. Full article

(This article belongs to the Special Issue Researches on Novel Antibacterial Agents)

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15 pages, 5858 KiB

Open AccessArticle

Copper-Catalyzed Ring-Opening Reactions of Alkyl Aziridines with B₂pin₂: Experimental and Computational Studies

by Lucilla Favero, Andrea Menichetti, Cosimo Boldrini, Lucrezia Margherita Comparini, Valeria Di Bussolo, Sebastiano Di Pietro and Mauro Pineschi

Molecules 2021, 26(23), 7399; https://doi.org/10.3390/molecules26237399 - 06 Dec 2021

Cited by 2 | Viewed by 2369

Abstract

The possibility to form new C–B bonds with aziridines using diboron derivatives continues to be a particularly challenging field in view of the direct preparation of functionalized β-aminoboronates, which are important compounds in drug discovery, being a bioisostere of β-aminoacids. We now report [...] Read more.

The possibility to form new C–B bonds with aziridines using diboron derivatives continues to be a particularly challenging field in view of the direct preparation of functionalized β-aminoboronates, which are important compounds in drug discovery, being a bioisostere of β-aminoacids. We now report experimental and computational data that allows the individuation of the structural requisites and of reaction conditions necessary to open alkyl aziridines using bis(pinacolate)diboron (B₂pin₂) in a regioselective nucleophilic addition reaction under copper catalysis. Full article

(This article belongs to the Special Issue Synthesis and Application of Organoboron Derivatives)

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18 pages, 44687 KiB

Open AccessArticle

Structural Characterization of Ectodomain G Protein of Respiratory Syncytial Virus and Its Interaction with Heparan Sulfate: Multi-Spectroscopic and In Silico Studies Elucidating Host-Pathogen Interactions

by Abu Hamza, Abdus Samad, Md. Ali Imam, Md. Imam Faizan, Anwar Ahmed, Fahad N. Almajhdi, Tajamul Hussain, Asimul Islam and Shama Parveen

Molecules 2021, 26(23), 7398; https://doi.org/10.3390/molecules26237398 - 06 Dec 2021

Cited by 4 | Viewed by 2211

Abstract

The global burden of disease caused by a respiratory syncytial virus (RSV) is becoming more widely recognized in young children and adults. Heparan sulfate helps in attaching the virion through G protein with the host cell membrane. In this study, we examined the [...] Read more.

The global burden of disease caused by a respiratory syncytial virus (RSV) is becoming more widely recognized in young children and adults. Heparan sulfate helps in attaching the virion through G protein with the host cell membrane. In this study, we examined the structural changes of ectodomain G protein (edG) in a wide pH range. The absorbance results revealed that protein maintains its tertiary structure at physiological and highly acidic and alkaline pH. However, visible aggregation of protein was observed in mild acidic pH. The intrinsic fluorescence study shows no significant change in the λ_max except at pH 12.0. The ANS fluorescence of edG at pH 2.0 and 3.0 forms an acid-induced molten globule-like state. The denaturation transition curve monitored by fluorescence spectroscopy revealed that urea and GdmCl induced denaturation native (N) ↔ denatured (D) state follows a two-state process. The fluorescence quenching, molecular docking, and 50 ns simulation measurements suggested that heparan sulfate showed excellent binding affinity to edG. Our binding study provides a preliminary insight into the interaction of edG to the host cell membrane via heparan sulfate. This binding can be inhibited using experimental approaches at the molecular level leading to the prevention of effective host–pathogen interaction. Full article

(This article belongs to the Special Issue Spectroscopic, Thermodynamic and Molecular Docking Studies on Molecular Mechanisms of Drug Binding to Proteins)

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21 pages, 4159 KiB

Open AccessArticle

A Report on Multi-Target Anti-Inflammatory Properties of Phytoconstituents from Monochoria hastata (Family: Pontederiaceae)

by Md Mazedul Haq, Md Arifur Rahman Chowdhury, Hilal Tayara, Ibrahim Abdelbaky, Md Shariful Islam, Kil To Chong and Sangyun Jeong

Molecules 2021, 26(23), 7397; https://doi.org/10.3390/molecules26237397 - 06 Dec 2021

Cited by 2 | Viewed by 2259

Abstract

This study aims to investigate the potential analgesic properties of the crude extract of Monochoria hastata (MH) leaves using in vivo experiments and in silico analysis. The extract, in a dose-dependent manner, exhibited a moderate analgesic property (~54% pain inhibition in acetic acid-induced [...] Read more.

This study aims to investigate the potential analgesic properties of the crude extract of Monochoria hastata (MH) leaves using in vivo experiments and in silico analysis. The extract, in a dose-dependent manner, exhibited a moderate analgesic property (~54% pain inhibition in acetic acid-induced writhing test), which is significant (** p < 0.001) as compared to the control group. The complex inflammatory mechanism involves diverse pathways and they are inter-connected. Therefore, multiple inflammatory modulator proteins were selected as the target for in silico analysis. Computational analysis suggests that all the selected targets had different degrees of interaction with the phytochemicals from the extract. Rutin (RU), protocatechuic acid (PA), vanillic acid (VA), and ferulic acid (FA) could regulate multiple targets with a robust efficiency. None of the compounds showed selectivity to Cyclooxygenase-2 (COX-2). However, regulation of COX and lipoxygenase (LOX) cascade by PA can reduce non-steroidal analgesic drugs (NSAIDs)-related side effects, including asthma. RU showed robust regulation of cytokine-mediated pathways like RAS/MAPK and PI3K/NF-kB by inhibition of EGFR and IKBα (IKK), which may prevent multi-organ failure due to cytokine storm in several microbial infections, for example, SARS-CoV-2. Further investigation, using in vivo and in vitro experiments, can be conducted to develop multi-target anti-inflammatory drugs using the isolated compounds from the extract. Full article

(This article belongs to the Special Issue Bioactivities and In Silico Study of Phytochemicals)

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21 pages, 4590 KiB

Open AccessArticle

Computational Screening for the Anticancer Potential of Seed-Derived Antioxidant Peptides: A Cheminformatic Approach

by Tsun-Thai Chai, Jiun-An Koh, Clara Chia-Ci Wong, Mohamad Zulkeflee Sabri and Fai-Chu Wong

Molecules 2021, 26(23), 7396; https://doi.org/10.3390/molecules26237396 - 06 Dec 2021

Cited by 12 | Viewed by 2798

Abstract

Some seed-derived antioxidant peptides are known to regulate cellular modulators of ROS production, including those proposed to be promising targets of anticancer therapy. Nevertheless, research in this direction is relatively slow owing to the inevitable time-consuming nature of wet-lab experimentations. To help expedite [...] Read more.

Some seed-derived antioxidant peptides are known to regulate cellular modulators of ROS production, including those proposed to be promising targets of anticancer therapy. Nevertheless, research in this direction is relatively slow owing to the inevitable time-consuming nature of wet-lab experimentations. To help expedite such explorations, we performed structure-based virtual screening on seed-derived antioxidant peptides in the literature for anticancer potential. The ability of the peptides to interact with myeloperoxidase, xanthine oxidase, Keap1, and p47^phox was examined. We generated a virtual library of 677 peptides based on a database and literature search. Screening for anticancer potential, non-toxicity, non-allergenicity, non-hemolyticity narrowed down the collection to five candidates. Molecular docking found LYSPH as the most promising in targeting myeloperoxidase, xanthine oxidase, and Keap1, whereas PSYLNTPLL was the best candidate to bind stably to key residues in p47^phox. Stability of the four peptide-target complexes was supported by molecular dynamics simulation. LYSPH and PSYLNTPLL were predicted to have cell- and blood-brain barrier penetrating potential, although intolerant to gastrointestinal digestion. Computational alanine scanning found tyrosine residues in both peptides as crucial to stable binding to the targets. Overall, LYSPH and PSYLNTPLL are two potential anticancer peptides that deserve deeper exploration in future. Full article

(This article belongs to the Special Issue Redox Active Molecules in Cancer Treatments)

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13 pages, 2715 KiB

Open AccessArticle

Targeted Separation of COX-2 Inhibitor from Pterocephalus hookeri Using Preparative High-Performance Liquid Chromatography Directed by the Affinity Solid-Phase Extraction HPLC System

by Yunhe Zhu, Weidong Wang, Lei Jiang, Hui Tan, Zenggen Liu, Sirong Jiang, Yanduo Tao, Huaixiu Wen and Lijuan Mei

Molecules 2021, 26(23), 7395; https://doi.org/10.3390/molecules26237395 - 06 Dec 2021

Cited by 3 | Viewed by 1755

Abstract

Pterocephalus hookeri, as a kind of popular traditional Tibetan medicine, is reputed to treat inflammatory related diseases. In the present work, a cyclooxygenase-2 functionalized affinity solid-phase extraction HPLC system was developed and combined with preparative-HPLC for rapidly screening and separating cyclooxygenase-2 ligand [...] Read more.

Pterocephalus hookeri, as a kind of popular traditional Tibetan medicine, is reputed to treat inflammatory related diseases. In the present work, a cyclooxygenase-2 functionalized affinity solid-phase extraction HPLC system was developed and combined with preparative-HPLC for rapidly screening and separating cyclooxygenase-2 ligand from P. hookeri extracts. Firstly, ligands of cyclooxygenase-2 were screened from extracts by affinity solid-phase extraction HPLC system. Then directed by the screening results, the recognized potential active compounds were targeted separated. As a result, the major cyclooxygenase-2 inhibitor of P. hookeri was obtained with a purity of >95%, which was identified as sylvestroside I. To test the accuracy of this method, the anti-inflammatory activity of sylvestroside I was inspected in lipopolysaccharide-induced RAW 264.7 cells. The results show that sylvestroside I significantly suppressed the release of prostaglandin E₂ with dose-dependent, which was in good agreement with the screening result of the affinity solid-phase method. This method of integration of screening and targeted separation proved to be very efficient for the recognition and isolation of cyclooxygenase-2 inhibitors from natural products. Full article

(This article belongs to the Special Issue Advanced Methodologies to Test Bioactive Compounds in Drug Discovery and in Food/Natural Products)

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12 pages, 1157 KiB

Open AccessArticle

Simple Ion–Gas Mixtures as a Source of Key Molecules Relevant to Prebiotic Chemistry

by Samuel Paula, Liam S. Goulding, Katherine N. Robertson and Jason A. C. Clyburne

Molecules 2021, 26(23), 7394; https://doi.org/10.3390/molecules26237394 - 06 Dec 2021

Cited by 1 | Viewed by 1619

Abstract

Very simple chemistry can result in the rapid and high-yield production of key prebiotic inorganic molecules. The two reactions investigated here involve such simple systems, (a) carbon disulfide (CS₂) and acetate (CH₃COO¯) and (b) sulfur dioxide (SO₂) [...] Read more.

Very simple chemistry can result in the rapid and high-yield production of key prebiotic inorganic molecules. The two reactions investigated here involve such simple systems, (a) carbon disulfide (CS₂) and acetate (CH₃COO¯) and (b) sulfur dioxide (SO₂) and formate (HCOO¯). They have been carried out under non-aqueous conditions, either in an organic solvent or with a powdered salt exposed to the requisite gas. Under such dry conditions the first reaction generated the thioacetate anion [CH₃COS]¯ while the second produced the radical [SO₂^·]¯anion. Anhydrous conditions are not rare and may have arisen on the early earth at sites where an interface between different phases (liquid/gas or solid/gas) could be generated. This is one way to rationalize the formation of molecules and ions (such as we have produced) necessary in the prebiotic world. Interpretation of our results provides insight into scenarios consistent with the more prominent theories of abiogenesis. Full article

(This article belongs to the Special Issue A Thematic Issue in Honor of Prof. Dr. Alan H. Cowley)

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11 pages, 2371 KiB

Open AccessArticle

Luteolin-3′-O-Phosphate Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Regulating NF-κB/MAPK Cascade Signaling in RAW 264.7 Cells

by Jung-Hwan Kim, Tae-Jin Park, Jin-Soo Park, Min-Seon Kim, Won-Jae Chi and Seung-Young Kim

Molecules 2021, 26(23), 7393; https://doi.org/10.3390/molecules26237393 - 06 Dec 2021

Cited by 9 | Viewed by 1787

Abstract

Luteolin (LT), present in most plants, has potent anti-inflammatory properties both in vitro and in vivo. Furthermore, some of its derivatives, such as luteolin-7-O-glucoside, also exhibit anti-inflammatory activity. However, the molecular mechanisms underlying luteolin-3′-O-phosphate (LTP)-mediated immune regulation are not [...] Read more.

Luteolin (LT), present in most plants, has potent anti-inflammatory properties both in vitro and in vivo. Furthermore, some of its derivatives, such as luteolin-7-O-glucoside, also exhibit anti-inflammatory activity. However, the molecular mechanisms underlying luteolin-3′-O-phosphate (LTP)-mediated immune regulation are not fully understood. In this paper, we compared the anti-inflammatory properties of LT and LTP and analyzed their molecular mechanisms of action; we obtained LTP via the biorenovation of LT. We investigated the anti-inflammatory activities of LT and LTP in macrophage RAW 264.7 cells. We confirmed from previously reported literature that LT inhibits the production of nitric oxide and prostaglandin E₂, as well as the expression of inducible NO synthetase and cyclooxygenase-2. In addition, expressions of inflammatory genes and mediators, such as tumor necrosis factor-α, interleukin-6, and interleukin-1β, were suppressed. LTP showed anti-inflammatory activity similar to LT, but better anti-inflammatory activity in all the experiments, while also inhibiting mitogen-activated protein kinase and nuclear factor-kappa B more effectively than LT. At a concentration of 10 μM, LTP showed differences of 2.1 to 44.5% in the activity compared to LT; it also showed higher anti-inflammatory activity. Our findings suggest that LTP has stronger anti-inflammatory activity than LT. Full article

(This article belongs to the Special Issue Natural Products for Cosmetic Applications)

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12 pages, 3153 KiB

Open AccessArticle

A Zn(II)-Based Sql Type 2D Coordination Polymer as a Highly Sensitive and Selective Turn-On Fluorescent Probe for Al³⁺

by Dmitry I. Pavlov, Alexey A. Ryadun and Andrei S. Potapov

Molecules 2021, 26(23), 7392; https://doi.org/10.3390/molecules26237392 - 06 Dec 2021

Cited by 6 | Viewed by 1997

Abstract

A luminescent coordination polymer with the overall formula {[Zn(tr₂btd)(bpdc)]∙DMF}_n (where tr₂btd = 4,7-di(1H-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole; bpdc = 4,4′-biphenyldicarboxylate) was synthesized and characterized by single-crystal and powder X-ray diffraction, thermogravimetric, infrared spectroscopy, and elemental analyses. Luminescent properties of the [...] Read more.

A luminescent coordination polymer with the overall formula {[Zn(tr₂btd)(bpdc)]∙DMF}_n (where tr₂btd = 4,7-di(1H-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole; bpdc = 4,4′-biphenyldicarboxylate) was synthesized and characterized by single-crystal and powder X-ray diffraction, thermogravimetric, infrared spectroscopy, and elemental analyses. Luminescent properties of the obtained compound were studied in detail both in the solid state and as a suspension in N,N-dimethylacetamide (DMA). It was found that {[Zn(tr₂btd)(bpdc)]∙DMF}_n exhibits bright turquoise luminescence with excellent quantum efficiency and demonstrates turn-on fluorescence enhancement effect upon soaking in DMA Al³⁺ solution. Fluorescence titration experiments were carried out and the detection limit for Al³⁺ ions was calculated to be 120 nM, which is among the lowest reported values for similar materials. Moreover, compound demonstrated excellent selectivity and reusability, and the mechanism of the response is discussed. These results indicate that {[Zn(tr₂btd)(bpdc)]∙DMF}_n is a promising probe for sensitive fluorescent Al³⁺ detection. Full article

(This article belongs to the Special Issue Advances in Optical Functional Metal-Organic Complexes, Metal-Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) and Coordination Polymers)

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17 pages, 3141 KiB

Open AccessArticle

Novel β-Cyclodextrin and Catnip Essential Oil Inclusion Complex and Its Tick Repellent Properties

by Jennifer Hogenbom, Mouaz Istanbouli and Nicoletta Faraone

Molecules 2021, 26(23), 7391; https://doi.org/10.3390/molecules26237391 - 06 Dec 2021

Cited by 8 | Viewed by 3202

Abstract

Cyclodextrin inclusion complexes have been successfully used to encapsulate essential oils, improving their physicochemical properties and pharmacological effects. Besides being well-known for its effects on cats and other felines, catnip (Nepeta cataria) essential oil demonstrates repellency against blood-feeding pests such as [...] Read more.

Cyclodextrin inclusion complexes have been successfully used to encapsulate essential oils, improving their physicochemical properties and pharmacological effects. Besides being well-known for its effects on cats and other felines, catnip (Nepeta cataria) essential oil demonstrates repellency against blood-feeding pests such as mosquitoes. This study evaluates the tick repellency of catnip oil alone and encapsulated in β-cyclodextrin, prepared using the co-precipitation method at a 1:1 molar ratio. The physicochemical properties of this inclusion complex were characterized using GC-FID for encapsulation efficiency and yield and SPME/GC-MS for volatile emission. Qualitative assessment of complex formation was done by UV-Vis, FT-IR, ¹H NMR, and SEM analyses. Catnip oil at 5% (v/v) demonstrated significant tick repellency over time, being comparable to DEET as used in commercial products. The prepared [catnip: β-CD] inclusion complex exerted significant tick repellency at lower concentration of the essential oil (equivalent of 1% v/v). The inclusion complex showed that the release of the active ingredient was consistent after 6 h, which could improve the effective repellent duration. These results demonstrated the effective tick repellent activity of catnip essential oil and the successful synthesis of the inclusion complex, suggesting that β-CDs are promising carriers to improve catnip oil properties and to expand its use in repellent formulations for tick management. Full article

(This article belongs to the Special Issue Cyclodextrin Chemistry and Toxicology II)

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10 pages, 1731 KiB

Open AccessArticle

Magnolol and Honokiol Inhibited the Function and Expression of BCRP with Mechanism Exploration

by Chung-Ping Yu, Pei-Ying Li, Szu-Yu Chen, Shiuan-Pey Lin and Yu-Chi Hou

Molecules 2021, 26(23), 7390; https://doi.org/10.3390/molecules26237390 - 06 Dec 2021

Cited by 11 | Viewed by 1987

Abstract

Breast cancer resistance protein (BCRP), one of the ATP-binding cassette (ABC) transporters, was associated with the multidrug resistance (MDR) of chemotherapy. Magnolol (MN) and honokiol (HK) are major bioactive polyphenols of Magnolia officinalis. This study investigated the effects of MN and HK [...] Read more.

Breast cancer resistance protein (BCRP), one of the ATP-binding cassette (ABC) transporters, was associated with the multidrug resistance (MDR) of chemotherapy. Magnolol (MN) and honokiol (HK) are major bioactive polyphenols of Magnolia officinalis. This study investigated the effects of MN and HK on the function and expression of BCRP for the purpose of developing BCRP inhibitor to overcome MDR. Cell lines including MDCKII-BCRP and MDCKII-WT were used for evaluating the function and expression of BCRP. The results showed that MN (100–12.5 µM) and HK (100–12.5 µM) significantly decreased the function of BCRP by 80~12% and 67~14%, respectively. In addition, MN and HK were verified as substrates of BCRP. Furthermore, MN and HK reduced the protein expression of BCRP, and inhibited the phosphorylation of epidermal growth factor receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K). In conclusion, both MN and HK decreased the function and expression of BCRP via EGFR/PI3K signaling pathway. Therefore, both compounds were promising candidates for reversing the MDR of chemotherapy. Full article

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13 pages, 2352 KiB

Open AccessArticle

Biological Response Profiling Reveals the Functional Differences of Main Alkaloids in Rhizoma Coptidis

by Lan Xie, Shanshan Feng, Xiaoling Zhang, Wenlong Zhao, Juan Feng, Chengmei Ma, Ruijun Wang, Weifang Song and Jing Cheng

Molecules 2021, 26(23), 7389; https://doi.org/10.3390/molecules26237389 - 06 Dec 2021

Cited by 6 | Viewed by 1639

Abstract

Rhizoma Coptidis (RC) is a widely used traditional Chinese medicine. Although modern research has found that some alkaloids from RC are the pharmacologically active constituents, the differences in their biological effects are not completely clear. This study analyzed the differences in the typical [...] Read more.

Rhizoma Coptidis (RC) is a widely used traditional Chinese medicine. Although modern research has found that some alkaloids from RC are the pharmacologically active constituents, the differences in their biological effects are not completely clear. This study analyzed the differences in the typical alkaloids in RC at a systematic level and provided comprehensive information on the pharmaceutical mechanisms of the different alkaloids. The ethanol RC extract (RCE) was characterized using HPLC assay. HepG2, 3T3-L1, and RAW264.7 cells were used to detect the cytotoxicity of alkaloids. Transcriptome analyses were performed to elucidate the cellular pathways affected by RCE and alkaloids. HPLC analysis revealed that the typical alkaloids of RCE were berberine, coptisine, and palmatine. Coptisine and berberine displayed a stronger inhibitory effect on cell proliferation than palmatine. The overlapping ratios of differentially expressed genes between RCE and berberine, coptisine, and palmatine were 70.8%, 52.6%, and 42.1%, respectively. Pathway clustering analysis indicated that berberine and coptisine possessed a certain similarity to RCE, and both compounds affected the cell cycle pathway; moreover, some pathways were uniquely enriched by berberine or coptisine. Berberine and coptisine had different regulatory effects on genes involved in lipid metabolism. These results provide comprehensive information on the pharmaceutical mechanisms of the different RC alkaloids and insights into their better combinatory use for the treatment of diseases. Full article

(This article belongs to the Section Natural Products Chemistry)

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12 pages, 1246 KiB

Open AccessArticle

Development of a Continuous System for 2-Phenylethanol Bioproduction by Yeast on Whey Permeate-Based Medium

by Karolina Drężek, Joanna Kozłowska, Anna Detman and Jolanta Mierzejewska

Molecules 2021, 26(23), 7388; https://doi.org/10.3390/molecules26237388 - 06 Dec 2021

Cited by 8 | Viewed by 2434

Abstract

2-Phenylethanol (2-PE) is an alcohol with a rosy scent and antimicrobial activity, and therefore, it is widely used in the food and cosmetic industries as an aroma and preservative. This work was aimed to draw up a technology for 2-PE bioproduction on whey [...] Read more.

2-Phenylethanol (2-PE) is an alcohol with a rosy scent and antimicrobial activity, and therefore, it is widely used in the food and cosmetic industries as an aroma and preservative. This work was aimed to draw up a technology for 2-PE bioproduction on whey permeate, which is waste produced by the dairy industry, rich in lactase and proteins. Its composition makes it a harmful waste to dispose of; however, with a properly selected microorganism, it could be converted to a value-added product. Herein, two yeast Kluyveromyces marxianus strains and one Kluyveromyces lactis, isolated from dairy products, were tested for 2-PE production, firstly on standard media and then on whey permeate based media in batch cultures. Thereafter, the 2-PE bioproduction in a continuous system in a 4.8 L bioreactor was developed, and subsequently, the final product was recovered from culture broth. The results showed that the yield of 2-PE production increased by 60% in the continuous culture compared to batch culture. Together with a notable reduction of chemical oxygen demand for whey permeate, the present study reports a complete, effective, and environmentally friendly strategy for 2-PE bioproduction with a space-time yield of 57.5 mg L⁻¹ h⁻¹. Full article

(This article belongs to the Collection Recent Advances in Flavors and Fragrances)

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16 pages, 1557 KiB

Open AccessArticle

Effect of Intrahippocampal Administration of α7 Subtype Nicotinic Receptor Agonist PNU-282987 and Its Solvent Dimethyl Sulfoxide on the Efficiency of Hypoxic Preconditioning in Rats

by Elena I. Zakharova, Andrey T. Proshin, Mikhail Y. Monakov and Alexander M. Dudchenko

Molecules 2021, 26(23), 7387; https://doi.org/10.3390/molecules26237387 - 06 Dec 2021

Viewed by 1387

Abstract

We have previously suggested a key role of the hippocampus in the preconditioning action of moderate hypobaric hypoxia (HBH). The preconditioning efficiency of HBH is associated with acoustic startle prepulse inhibition (PPI). In rats with PPI > 40%, HBH activates the cholinergic projections [...] Read more.

We have previously suggested a key role of the hippocampus in the preconditioning action of moderate hypobaric hypoxia (HBH). The preconditioning efficiency of HBH is associated with acoustic startle prepulse inhibition (PPI). In rats with PPI > 40%, HBH activates the cholinergic projections of hippocampus, and PNU-282987, a selective agonist of α7 nicotinic receptors (α7nAChRs), reduces the HBH efficiency and potentiating effect on HBH of its solvent dimethyl sulfoxide (DMSO, anticholinesterase agent) when administered intraperitoneally. In order to validate the hippocampus as a key structure in the mechanism of hypoxic preconditioning and research a significance of α7nAChR activation in the hypoxic preconditioning, we performed an in vivo pharmacological study of intrahippocampal injections of PNU-282987 into the CA1 area on HBH efficiency in rats with PPI ≥ 40%. We found that PNU-282987 (30 μM) reduced HBH efficiency as with intraperitoneal administration, while DMSO (0.05%) still potentiated this effect. Thus, direct evidence of the key role of the hippocampus in the preconditioning effect of HBH and some details of this mechanism were obtained in rats with PPI ≥ 40%. The activation of α7nAChRs is not involved in the cholinergic signaling initiated by HBH or DMSO via any route of administration. Possible ways of the potentiating action of DMSO on HBH efficiency and its dependence on α7nAChRs are discussed. Full article

(This article belongs to the Special Issue Nicotinic Receptors: Pharmacological Studies, Design and Synthesis of Pharmacologically Active Substances)

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11 pages, 3943 KiB

Open AccessArticle

Influence of the Substituents on the Opening of Silylepoxy Alcohols: 5-exo-Cyclization towards Tetrahydrofurans vs. Unexpected Side Reaction Leading to Tetrahydropyrans

by Carlos Díez-Poza and Asunción Barbero

Molecules 2021, 26(23), 7386; https://doi.org/10.3390/molecules26237386 - 06 Dec 2021

Viewed by 1606

Abstract

The regioselective ring opening of epoxy alcohols is an effective method for the synthesis of different types of oxacycles. The 5-exo opening being preferred vs. the 6-endo mode, according to Baldwin rules, the use of silyl-substituted oxiranes has been reported as [...] Read more.

The regioselective ring opening of epoxy alcohols is an effective method for the synthesis of different types of oxacycles. The 5-exo opening being preferred vs. the 6-endo mode, according to Baldwin rules, the use of silyl-substituted oxiranes has been reported as a possible method to favor the 6-endo cyclization. However, there is a need for a detailed study on the different factors (structural factors, catalyst nature or conditions) that influence this process. In this paper, the acid-catalyzed cyclization of epoxysilyl alcohols was studied, focusing on the effect of substituents and reaction conditions on the outcome of the process. Two types of heterocycles (tetrahydrofurans or tetrahydropyrans) were selectively obtained depending on the structure of the initial epoxysilyl alcohol. Interestingly, cyclization of hindered epoxysilyl alcohols mainly proceeds through an unexpected side reaction, which implies a previous isomerization to an aldehyde. A mechanistic proposal for the formation of the different products is presented. Full article

(This article belongs to the Special Issue Molecules from Side Reactions II)

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17 pages, 4669 KiB

Open AccessArticle

Computational Simulation of HIV Protease Inhibitors to the Main Protease (Mpro) of SARS-CoV-2: Implications for COVID-19 Drugs Design

by Wei Yu, Xiaomin Wu, Yizhen Zhao, Chun Chen, Zhiwei Yang, Xiaochun Zhang, Jiayi Ren, Yueming Wang, Changwen Wu, Chengming Li, Rongfeng Chen, Xiaoli Wang, Weihong Zheng, Huaxin Liao and Xiaohui Yuan

Molecules 2021, 26(23), 7385; https://doi.org/10.3390/molecules26237385 - 05 Dec 2021

Cited by 6 | Viewed by 2670

Abstract

SARS-CoV-2 is highly homologous to SARS-CoV. To date, the main protease (Mpro) of SARS-CoV-2 is regarded as an important drug target for the treatment of Coronavirus Disease 2019 (COVID-19). Some experiments confirmed that several HIV protease inhibitors present the inhibitory effects on the [...] Read more.

SARS-CoV-2 is highly homologous to SARS-CoV. To date, the main protease (Mpro) of SARS-CoV-2 is regarded as an important drug target for the treatment of Coronavirus Disease 2019 (COVID-19). Some experiments confirmed that several HIV protease inhibitors present the inhibitory effects on the replication of SARS-CoV-2 by inhibiting Mpro. However, the mechanism of action has still not been studied very clearly. In this work, the interaction mechanism of four HIV protease inhibitors Darunavir (DRV), Lopinavir (LPV), Nelfinavir (NFV), and Ritonavire (RTV) targeting SARS-CoV-2 Mpro was explored by applying docking, molecular dynamics (MD) simulations, and MM–GBSA methods using the broad-spectrum antiviral drug Ribavirin (RBV) as the negative and nonspecific control. Our results revealed that LPV, RTV, and NFV have higher binding affinities with Mpro, and they all interact with catalytic residues His41 and the other two key amino acids Met49 and Met165. Pharmacophore model analysis further revealed that the aromatic ring, hydrogen bond donor, and hydrophobic group are the essential infrastructure of Mpro inhibitors. Overall, this study applied computational simulation methods to study the interaction mechanism of HIV-1 protease inhibitors with SARS-CoV-2 Mpro, and the findings provide useful insights for the development of novel anti-SARS-CoV-2 agents for the treatment of COVID-19. Full article

(This article belongs to the Special Issue Molecules to Fight SARS-CoV-2 Infection)

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18 pages, 3833 KiB

Open AccessArticle

Development of New Efficient Adsorbent by Functionalization of Mg₃Al-LDH with Methyl Trialkyl Ammonium Chloride Ionic Liquid

by Samuel Nick Țolea, Laura Cocheci, Lavinia Lupa, Raluca Vodă and Rodica Pode

Molecules 2021, 26(23), 7384; https://doi.org/10.3390/molecules26237384 - 05 Dec 2021

Cited by 4 | Viewed by 1476

Abstract

The present paper describes a new way of obtaining an efficient adsorbent material by functionalization of Mg₃Al layered double hydroxides (LDH) with methyl trialkyl ammonium chloride-ionic liquid (IL) using two methods: ultrasound and cosynthesis. Layered double hydroxides are good solid support [...] Read more.

The present paper describes a new way of obtaining an efficient adsorbent material by functionalization of Mg₃Al layered double hydroxides (LDH) with methyl trialkyl ammonium chloride-ionic liquid (IL) using two methods: ultrasound and cosynthesis. Layered double hydroxides are good solid support for the functionalization with ionic liquids due to their well-ordered structure. The immobilization of the ILs in suitable solid supports combine the advantages of the ILs with the properties of the solid supports bringing more benefits such as use of lower quantity of ILs and avoiding of ILs loss in the aqua phase which overall decrease the treatment costs. In case of ultrasound method of functionalization is assured a uniform distribution of IL on the solid surface, but through immobilization by cosynthesis due to the tunable properties of LDH, is assured an intercalation of the ILs between the LDH layers. This fact was highlighted by the X-ray diffraction (RXD), scanning electron microscopy (SEM) analyses and Fourier-transform infrared (FTIR) spectroscopy of the obtained adsorbent. The added value brought by the functionalization of Mg₃Al with the studied IL was underlined by the adsorption studies conducted in the treatment process of water with diclofenac content. Kinetic, thermodynamic, and equilibrium studies were performed. DCF adsorption onto the studied materials correspond to a chemisorption, the pseudo-second-order kinetic model describing the most accurately the experimental data. DCF adsorption onto the studied materials occurs as a heterogeneous process, with the experimental data fitting best with the SIPS isotherm. The sample obtained through cosynthesis developed a maximum adsorption capacity of 648 mg/g. Full article

(This article belongs to the Special Issue New Applications of Layered Double Hydroxide-Based Materials)

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42 pages, 7046 KiB

Open AccessArticle

Altitudinal Variation of Metabolites, Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

by Tingting Dong, Yueqi Sha, Hairong Liu and Liwei Sun

Molecules 2021, 26(23), 7383; https://doi.org/10.3390/molecules26237383 - 05 Dec 2021

Cited by 4 | Viewed by 2061

Abstract

Rhodiolacrenulata (Hook.f. & Thomson) H.Ohba is an alpine medicinal plant that can survive in extreme high altitude environments. However, its changes to extreme high altitude are not yet clear. In this study, the response of Rhodiola crenulata to differences in altitude gradients [...] Read more.

Rhodiolacrenulata (Hook.f. & Thomson) H.Ohba is an alpine medicinal plant that can survive in extreme high altitude environments. However, its changes to extreme high altitude are not yet clear. In this study, the response of Rhodiola crenulata to differences in altitude gradients was investigated through chemical, ICP-MS and metabolomic methods. A targeted study of Rhodiola crenulata growing at three vertical altitudes revealed that the contents of seven elements Ca, Sr, B, Mn, Ni, Cu, and Cd, the phenolic components, the ascorbic acid, the ascorbic acid/dehydroascorbate ratio, and the antioxidant capacity were positively correlated with altitude, while the opposite was true for total ascorbic acid content. Furthermore, 1165 metabolites were identified: flavonoids (200), gallic acids (30), phenylpropanoids (237), amino acids (100), free fatty acids and glycerides (56), nucleotides (60), as well as other metabolites (482). The differential metabolite and biomarker analyses suggested that, with an increasing altitude: (1) the shikimic acid-phenylalanine-phenylpropanoids-flavonoids pathway was enhanced, with phenylpropanoids upregulating biomarkers much more than flavonoids; phenylpropanes and phenylmethanes upregulated, and phenylethanes downregulated; the upregulation of quercetin was especially significant in flavonoids; upregulation of condensed tannins and downregulation of hydrolyzed tannins; upregulation of shikimic acids and amino acids including phenylalanine. (2) significant upregulation of free fatty acids and downregulation of glycerides; and (3) upregulation of adenosine phosphates. Our findings provide new insights on the responses of Rhodiola crenulata to extreme high altitude adversity. Full article

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