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Natural Products: Therapeutic Properties and Beyond

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 73915

Special Issue Editors


E-Mail Website1 Website2
Guest Editor
Centro de Investigação em Ciências da Saúde | Universidade da Beira Interior, Covilhã, Portugal
Interests: plant extracts; biological activities of natural products; bioaccessibility and bioavailability of phenolic compounds
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
CICS-UBI Health Sciences Research Centre, Universidade da Beira Interior, Covilhã, Portugal
Interests: plant extracts; essential oils; polyphenols; antioxidant and antimicrobial properties; functional films
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
1. Health Sciences Research Centre, University of Beira Interior (CICS-UBI), Covilhã, Portugal
2. Pharmaco-Toxicology Laboratory, UBIMedical, University of Beira Interior, Covilhã, Portugal
3. Centro Académico Clínico das Beiras (CACB)—Grupo de Problemas Relacionados com Toxicofilias, Covilhã, Portugal
Interests: toxicology; analytical method development; recreational drugs; natural psychoactive substances; therapeutic drug monitoring; sample preparation; alternative samples; miniaturized extraction procedures
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear colleague,

Natural products present a great variety of chemical and structural properties, and in recent years, new developments concerning these compounds have widened the horizon of research applications, aiming at obtaining new agents for human therapy. However, their beneficial effects on human health are far from being the only features of these products, as recreational or abused consumption of certain compounds of natural origin is also alarming.

With this Special Issue, we aim to categorize the state-of-the-art concerning scientific research on natural products, including their applications as compounds of added value to human health.

Presenting a very broad scope, this Special Issue welcomes full papers, short communications, and review articles on, but not limited to, physiologically active compounds (namely from terrestrial or marine plants); secondary metabolites of microorganisms (for instance, antibiotics and mycotoxins); biochemical studies, isolation, structure elucidation, and chemical synthetic pathways of novel compounds from natural origin; pharmacology of naturally occurring compounds; and development of new detection and quantification methods.

This issue should serve as a text for academia, or as a reference tool for researchers, particularly those working in the fields of medicinal chemistry, toxicology, phytochemistry, natural product chemistry, and health and industry professionals as well.

Prof. Dr. Ana Paula Duarte
Dr. Ângelo Luís
Dr. Eugenia Gallardo
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Natural products
  • Secondary metabolites
  • Drug discovery
  • Therapeutic properties
  • Recreational use
  • Analysis

Published Papers (15 papers)

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Research

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17 pages, 1622 KiB  
Article
A Novel Dual Drug Approach That Combines Ivermectin and Dihydromyricetin (DHM) to Reduce Alcohol Drinking and Preference in Mice
by Joshua Silva, Eileen Carry, Chen Xue, Jifeng Zhang, Jing Liang, Jacques Y. Roberge and Daryl L. Davies
Molecules 2021, 26(6), 1791; https://doi.org/10.3390/molecules26061791 - 22 Mar 2021
Cited by 7 | Viewed by 3009
Abstract
Alcohol use disorder (AUD) affects over 18 million people in the US. Unfortunately, pharmacotherapies available for AUD have limited clinical success and are under prescribed. Previously, we established that avermectin compounds (ivermectin [IVM] and moxidectin) reduce alcohol (ethanol/EtOH) consumption in mice, but these [...] Read more.
Alcohol use disorder (AUD) affects over 18 million people in the US. Unfortunately, pharmacotherapies available for AUD have limited clinical success and are under prescribed. Previously, we established that avermectin compounds (ivermectin [IVM] and moxidectin) reduce alcohol (ethanol/EtOH) consumption in mice, but these effects are limited by P-glycoprotein (Pgp/ABCB1) efflux. The current study tested the hypothesis that dihydromyricetin (DHM), a natural product suggested to inhibit Pgp, will enhance IVM potency as measured by changes in EtOH consumption. Using a within-subjects study design and two-bottle choice study, we tested the combination of DHM (10 mg/kg; i.p.) and IVM (0.5–2.5 mg/kg; i.p.) on EtOH intake and preference in male and female C57BL/6J mice. We also conducted molecular modeling studies of DHM with the nucleotide-binding domain of human Pgp that identified key binding residues associated with Pgp inhibition. We found that DHM increased the potency of IVM in reducing EtOH consumption, resulting in significant effects at the 1.0 mg/kg dose. This combination supports our hypothesis that inhibiting Pgp improves the potency of IVM in reducing EtOH consumption. Collectively, we demonstrate the feasibility of this novel combinatorial approach in reducing EtOH consumption and illustrate the utility of DHM in a novel combinatorial approach. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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13 pages, 1406 KiB  
Article
Impact of Matrix Metalloproteinase-9 during Periodontitis and Cardiovascular Diseases
by Gaetano Isola, Alessandro Polizzi, Vincenzo Ronsivalle, Angela Alibrandi, Giuseppe Palazzo and Antonino Lo Giudice
Molecules 2021, 26(6), 1777; https://doi.org/10.3390/molecules26061777 - 22 Mar 2021
Cited by 15 | Viewed by 2778
Abstract
Matrix metalloproteinase-9 (MMP-9) has been shown to play a key role in endothelial function and perhaps pivotal in the correlation between periodontal disease and cardiovascular disease (CVD). For the study, the impact of MMP-9 of periodontitis and CVD on serum and saliva concentrations [...] Read more.
Matrix metalloproteinase-9 (MMP-9) has been shown to play a key role in endothelial function and perhaps pivotal in the correlation between periodontal disease and cardiovascular disease (CVD). For the study, the impact of MMP-9 of periodontitis and CVD on serum and saliva concentrations was analyzed. For the study patients with periodontitis (n = 31), CVD (n = 31), periodontitis + CVD (n = 31), and healthy patients (n = 31) were enrolled. Clinical and demographic characteristics as well as serum and salivary MMP-9 were evaluated. MMP-9 concentrations in serum and saliva were statistically elevated in patients with CVD (p < 0.01) and in patients with periodontitis plus CVD (p < 0.001) compared to patients with periodontitis and healthy subjects. Multivariate regression analysis showed that c-reactive protein (hs-CRP) was the only significant predictor for MMP-9 serum (p < 0.001), whereas hs-CRP (p < 0.001) and total cholesterol (p = 0.029) were the statistically significant salivary MMP-9 predictors. This study evidenced that patients with CVD and periodontitis + CVD presented elevated MMP-9 concentrations in serum and saliva compared to patients with periodontitis and healthy subjects. Furthermore, hs-CRP was a negative predictor of serum and salivary MMP-9. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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14 pages, 9500 KiB  
Article
Assessing the Molecular Targets and Mode of Action of Furanone C-30 on Pseudomonas aeruginosa Quorum Sensing
by Victor Markus, Karina Golberg, Kerem Teralı, Nazmi Ozer, Esti Kramarsky-Winter, Robert S. Marks and Ariel Kushmaro
Molecules 2021, 26(6), 1620; https://doi.org/10.3390/molecules26061620 - 15 Mar 2021
Cited by 14 | Viewed by 3082
Abstract
Quorum sensing (QS), a sophisticated system of bacterial communication that depends on population density, is employed by many pathogenic bacteria to regulate virulence. In view of the current reality of antibiotic resistance, it is expected that interfering with QS can address bacterial pathogenicity [...] Read more.
Quorum sensing (QS), a sophisticated system of bacterial communication that depends on population density, is employed by many pathogenic bacteria to regulate virulence. In view of the current reality of antibiotic resistance, it is expected that interfering with QS can address bacterial pathogenicity without stimulating the incidence of resistance. Thus, harnessing QS inhibitors has been considered a promising approach to overriding bacterial infections and combating antibiotic resistance that has become a major threat to public healthcare around the globe. Pseudomonas aeruginosa is one of the most frequent multidrug-resistant bacteria that utilize QS to control virulence. Many natural compounds, including furanones, have demonstrated strong inhibitory effects on several pathogens via blocking or attenuating QS. While the natural furanones show no activity against P. aeruginosa, furanone C-30, a brominated derivative of natural furanone compounds, has been reported to be a potent inhibitor of the QS system of the notorious opportunistic pathogen. In the present study, we assess the molecular targets and mode of action of furanone C-30 on P. aeruginosa QS system. Our results suggest that furanone C-30 binds to LasR at the ligand-binding site but fails to establish interactions with the residues crucial for the protein’s productive conformational changes and folding, thus rendering the protein dysfunctional. We also show that furanone C-30 inhibits RhlR, independent of LasR, suggesting a complex mechanism for the agent beyond what is known to date. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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8 pages, 768 KiB  
Article
Assessment of Conventional Solvent Extraction vs. Supercritical Fluid Extraction of Khella (Ammi visnaga L.) Furanochromones and Their Cytotoxicity
by Noha Khalil, Mokhtar Bishr, Mohamed El-Degwy, Mohamed Abdelhady, Mohamed Amin and Osama Salama
Molecules 2021, 26(5), 1290; https://doi.org/10.3390/molecules26051290 - 27 Feb 2021
Cited by 8 | Viewed by 2924
Abstract
Background: Khella (Ammi visnaga Lam.) fruits (Apiaceae) are rich in furanochromones, mainly khellin and visnagin, and are thus incorporated in several pharmaceutical products used mainly for treatment of renal stones. Methods: The objective of this study was to compare the yield of [...] Read more.
Background: Khella (Ammi visnaga Lam.) fruits (Apiaceae) are rich in furanochromones, mainly khellin and visnagin, and are thus incorporated in several pharmaceutical products used mainly for treatment of renal stones. Methods: The objective of this study was to compare the yield of khellin and visnagin obtained using different conventional solvents and supercritical fluid extraction (SCFE) with carbon dioxide (containing 5% methanol as co-solvent). Water, acetone and ethanol (30% and 95%) were selected as conventional solvents. Results: Highest extract yield was obtained from 30% ethanol (15.44%), while SCFE gave the lowest yield (4.50%). However, the percentage of furanochromones were highest in SCFE (30.1%), and lowest in boiling water extract (5.95%). HPLC analysis of conventional solvent extracts showed other coumarins that did not appear in supercritical fluid extraction chromatogram due to non-selectivity of solvent extraction. Ammi visnaga extracts as well as standard khellin and visnagin were tested for their cytotoxic activity using sulforhodamine B assay on breast cancer (MCF-7) and hepatocellular carcinoma (Hep G2) cell lines. Results revealed a strong cytotoxic activity (IC50 < 20 µg/mL) for the SCFE and standard compounds (khellin and visnagin) (IC50 ranging between 12.54 ± 0.57 and 17.53 ± 1.03 µg/mL). However, ethanol and acetone extracts had moderate cytotoxic activity (IC50 20–90 µg/mL) and aqueous extract had a weak activity (IC50 > 90 µg/mL). Conclusions: Thus, supercritical fluid extraction is an efficient, relatively safe, and cheap technique that yielded a more selective purified extract with better cytotoxic activity. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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10 pages, 1277 KiB  
Article
PSC-db: A Structured and Searchable 3D-Database for Plant Secondary Compounds
by Alejandro Valdés-Jiménez, Carlos Peña-Varas, Paola Borrego-Muñoz, Lily Arrue, Melissa Alegría-Arcos, Hussam Nour-Eldin, Ingo Dreyer, Gabriel Nuñez-Vivanco and David Ramírez
Molecules 2021, 26(4), 1124; https://doi.org/10.3390/molecules26041124 - 20 Feb 2021
Cited by 10 | Viewed by 3559
Abstract
Plants synthesize a large number of natural products, many of which are bioactive and have practical values as well as commercial potential. To explore this vast structural diversity, we present PSC-db, a unique plant metabolite database aimed to categorize the diverse phytochemical space [...] Read more.
Plants synthesize a large number of natural products, many of which are bioactive and have practical values as well as commercial potential. To explore this vast structural diversity, we present PSC-db, a unique plant metabolite database aimed to categorize the diverse phytochemical space by providing 3D-structural information along with physicochemical and pharmaceutical properties of the most relevant natural products. PSC-db may be utilized, for example, in qualitative estimation of biological activities (Quantitative Structure-Activity Relationship, QSAR) or massive docking campaigns to identify new bioactive compounds, as well as potential binding sites in target proteins. PSC-db has been implemented using the open-source PostgreSQL database platform where all compounds with their complementary and calculated information (classification, redundant names, unique IDs, physicochemical properties, etc.) were hierarchically organized. The source organism for each compound, as well as its biological activities against protein targets, cell lines and different organism were also included. PSC-db is freely available for public use and is hosted at the Universidad de Talca. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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13 pages, 1646 KiB  
Article
Synthesis of [18F]F-γ-T-3, a Redox-Silent γ-Tocotrienol (γ-T-3) Vitamin E Analogue for Image-Based In Vivo Studies of Vitamin E Biodistribution and Dynamics
by Peter Roselt, Carleen Cullinane, Wayne Noonan, Hassan Elsaidi, Peter Eu and Leonard I. Wiebe
Molecules 2020, 25(23), 5700; https://doi.org/10.3390/molecules25235700 - 03 Dec 2020
Viewed by 1959
Abstract
Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers [...] Read more.
Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, β-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E’s biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[18F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([18F]F-γ-T-3) was prepared for this purpose. [18F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [18F]fluoride in DMF/K222. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [18F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [18F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [18F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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15 pages, 2493 KiB  
Article
Rapid Quantification and Validation of Biomarker Scopoletin in Paederia foetida by qNMR and UV–Vis for Herbal Preparation
by Dai Chuan Tan, Alexandra Quek, Nur Kartinee Kassim, Intan Safinar Ismail and Joanna Jinling Lee
Molecules 2020, 25(21), 5162; https://doi.org/10.3390/molecules25215162 - 06 Nov 2020
Cited by 8 | Viewed by 2847
Abstract
Scopoletin has previously been reported as a biomarker for the standardization of Paederia foetida twigs. This study is the first report on the determination and quantification of scopoletin using quantitative nuclear magnetic resonance (qNMR) in the different extracts of Paederia foetida twigs. The [...] Read more.
Scopoletin has previously been reported as a biomarker for the standardization of Paederia foetida twigs. This study is the first report on the determination and quantification of scopoletin using quantitative nuclear magnetic resonance (qNMR) in the different extracts of Paederia foetida twigs. The validated qNMR method showed a good linearity (r2 = 0.9999), limit of detection (LOD) (0.009 mg/mL), and quantification (LOQ) (0.029 mg/mL), together with high stability (relative standard deviation (RSD) = 0.022%), high precision (RSD < 1%), and good recovery (94.08–108.45%). The quantification results of scopoletin concentration in chloroform extract using qNMR and microplate ultraviolet-visible (UV-vis) spectrophotometer was almost comparable. Therefore, the qNMR method is deemed accurate and reliable for quality control of Paederia foetida and other medicinal plants without extensive sample preparation. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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22 pages, 5191 KiB  
Article
Green Synthesis of Zinc Oxide Nanoparticles from Pomegranate (Punica granatum) Extracts and Characterization of Their Antibacterial Activity
by Ugochi Lydia Ifeanyichukwu, Omolola Esther Fayemi and Collins Njie Ateba
Molecules 2020, 25(19), 4521; https://doi.org/10.3390/molecules25194521 - 02 Oct 2020
Cited by 87 | Viewed by 7766
Abstract
This study assessed the antimicrobial efficacy of synthesized zinc oxide nanoparticles produced using aqueous extracts of pomegranate leaves and flowers designated ZnO-NPs-PL, ZnO-NPs-PF. In the study, oxides of zinc were successfully employed to fabricate nanoparticles using extracts from leaves and flowers of pomegranate [...] Read more.
This study assessed the antimicrobial efficacy of synthesized zinc oxide nanoparticles produced using aqueous extracts of pomegranate leaves and flowers designated ZnO-NPs-PL, ZnO-NPs-PF. In the study, oxides of zinc were successfully employed to fabricate nanoparticles using extracts from leaves and flowers of pomegranate (Punica granatum). The nanoparticles obtained were characterized spectroscopically. X-ray diffractive analysis (XRD) revealed the elemental components and nature of the synthesized particles. The fabricated zinc oxide nanoparticle (ZnO-NPs) showed a crystalline structure. The morphology of the nanoparticles as shown by scanning electron microscopy (SEM) was unevenly spherical and the functional groups involved in stabilization, reduction and capping were confirmed using Fourier Transform Infra-Red (FT-IR) Spectroscopy. Confirmation of the nanoparticles by UV–Vis analysis showed absorption bands of 284 and 357 nm for pomegranate leaf and flower extract, respectively, mediated ZnO-NPs. Evaluation of the antimicrobial efficacy of the fabricated nanoparticles showed that ZnO-NPs were effective against all selected pathogenic strains, Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Salmonella diarizonae, Salmonella typhi, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Moraxella catarrhalis, Aeromonas hydrophila and Listeria monocytogenes, used in the analysis. The effectiveness of these nanoparticles could be linked to their sizes and shapes as obtained using a transmission electron microscope (TEM) and scanning electron microscope (SEM). Our reports revealed that increasing the concentration of the nanoparticles resulted in an increase in the antibacterial activity exerted by the nanoparticles, thus suggesting that both ZnO-NPs can effectively be used as alternative antibacterial agents. Further research is required to assess their mechanisms of action and toxicity. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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17 pages, 2198 KiB  
Article
Chemical Characterisation and Antihypertensive Effects of Locular Gel and Serum of Lycopersicum esculentum L. var. “Camone” Tomato in Spontaneously Hypertensive Rats
by Paola Marcolongo, Alessandra Gamberucci, Gabriella Tamasi, Alessio Pardini, Claudia Bonechi, Claudio Rossi, Roberta Giunti, Virginia Barone, Annalisa Borghini, Paolo Fiorenzani, Maria Frosini, Massimo Valoti and Federica Pessina
Molecules 2020, 25(16), 3758; https://doi.org/10.3390/molecules25163758 - 18 Aug 2020
Cited by 12 | Viewed by 3526
Abstract
Blood pressure control in hypertensive subjects calls for changes in lifestyle, especially diet. Tomato is widely consumed and rich in healthy components (i.e., carotenoids, vitamins and polyphenols). The aim of this study was to evaluate the chemical composition and antihypertensive effects of locular [...] Read more.
Blood pressure control in hypertensive subjects calls for changes in lifestyle, especially diet. Tomato is widely consumed and rich in healthy components (i.e., carotenoids, vitamins and polyphenols). The aim of this study was to evaluate the chemical composition and antihypertensive effects of locular gel reconstituted in serum of green tomatoes of “Camone” variety. Tomato serum and locular gel were chemically characterised. The antihypertensive effects of the locular gel in serum, pure tomatine, and captopril, administered by oral gavage, were investigated for 4 weeks in male spontaneously hypertensive and normotensive rats. Systolic blood pressure and heart rate were monitored using the tail cuff method. Body and heart weight, serum glucose, triglycerides and inflammatory cytokines, aorta thickness and liver metabolising activity were also assessed. Locular gel and serum showed good tomatine and polyphenols content. Significant reductions in blood pressure and heart rate, as well as in inflammatory blood cytokines and aorta thickness, were observed in spontaneously hypertensive rats treated both with locular gel in serum and captopril. No significant effects were observed in normotensive rats. Green tomatoes locular gel and serum, usually discarded during tomato industrial processing, are rich in bioactive compounds (i.e., chlorogenic acid, caffeic acid and rutin, as well as the glycoalkaloids, α-tomatine and dehydrotomatine) that can lower in vivo blood pressure towards healthier values, as observed in spontaneously hypertensive rats. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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Review

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29 pages, 3478 KiB  
Review
Diversity in Chemical Structures and Biological Properties of Plant Alkaloids
by Sweta Bhambhani, Kirtikumar R. Kondhare and Ashok P. Giri
Molecules 2021, 26(11), 3374; https://doi.org/10.3390/molecules26113374 - 03 Jun 2021
Cited by 96 | Viewed by 11197
Abstract
Phytochemicals belonging to the group of alkaloids are signature specialized metabolites endowed with countless biological activities. Plants are armored with these naturally produced nitrogenous compounds to combat numerous challenging environmental stress conditions. Traditional and modern healthcare systems have harnessed the potential of these [...] Read more.
Phytochemicals belonging to the group of alkaloids are signature specialized metabolites endowed with countless biological activities. Plants are armored with these naturally produced nitrogenous compounds to combat numerous challenging environmental stress conditions. Traditional and modern healthcare systems have harnessed the potential of these organic compounds for the treatment of many ailments. Various chemical entities (functional groups) attached to the central moiety are responsible for their diverse range of biological properties. The development of the characterization of these plant metabolites and the enzymes involved in their biosynthesis is of an utmost priority to deliver enhanced advantages in terms of biological properties and productivity. Further, the incorporation of whole/partial metabolic pathways in the heterologous system and/or the overexpression of biosynthetic steps in homologous systems have both become alternative and lucrative methods over chemical synthesis in recent times. Moreover, in-depth research on alkaloid biosynthetic pathways has revealed numerous chemical modifications that occur during alkaloidal conversions. These chemical reactions involve glycosylation, acylation, reduction, oxidation, and methylation steps, and they are usually responsible for conferring the biological activities possessed by alkaloids. In this review, we aim to discuss the alkaloidal group of plant specialized metabolites and their brief classification covering major categories. We also emphasize the diversity in the basic structures of plant alkaloids arising through enzymatically catalyzed structural modifications in certain plant species, as well as their emerging diverse biological activities. The role of alkaloids in plant defense and their mechanisms of action are also briefly discussed. Moreover, the commercial utilization of plant alkaloids in the marketplace displaying various applications has been enumerated. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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19 pages, 556 KiB  
Review
Vitamin A and Bone Health: A Review on Current Evidence
by Michelle Min Fang Yee, Kok-Yong Chin, Soelaiman Ima-Nirwana and Sok Kuan Wong
Molecules 2021, 26(6), 1757; https://doi.org/10.3390/molecules26061757 - 21 Mar 2021
Cited by 33 | Viewed by 7480
Abstract
Vitamin A is a fat-soluble micronutrient essential for growth, immunity, and good vision. The preformed retinol is commonly found in food of animal origin whereas provitamin A is derived from food of plant origin. This review summarises the current evidence from animal, human [...] Read more.
Vitamin A is a fat-soluble micronutrient essential for growth, immunity, and good vision. The preformed retinol is commonly found in food of animal origin whereas provitamin A is derived from food of plant origin. This review summarises the current evidence from animal, human and cell-culture studies on the effects of vitamin A towards bone health. Animal studies showed that the negative effects of retinol on the skeleton were observed at higher concentrations, especially on the cortical bone. In humans, the direct relationship between vitamin A and poor bone health was more pronounced in individuals with obesity or vitamin D deficiency. Mechanistically, vitamin A differentially influenced the stages of osteogenesis by enhancing early osteoblastic differentiation and inhibiting bone mineralisation via retinoic acid receptor (RAR) signalling and modulation of osteocyte/osteoblast-related bone peptides. However, adequate vitamin A intake through food or supplements was shown to maintain healthy bones. Meanwhile, provitamin A (carotene and β-cryptoxanthin) may also protect bone. In vitro evidence showed that carotene and β-cryptoxanthin may serve as precursors for retinoids, specifically all-trans-retinoic acid, which serve as ligand for RARs to promote osteogenesis and suppressed nuclear factor-kappa B activation to inhibit the differentiation and maturation of osteoclasts. In conclusion, we suggest that both vitamin A and provitamin A may be potential bone-protecting agents, and more studies are warranted to support this hypothesis. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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26 pages, 5219 KiB  
Review
Psychoactive Substances of Natural Origin: Toxicological Aspects, Therapeutic Properties and Analysis in Biological Samples
by Joana Gonçalves, Ângelo Luís, Eugenia Gallardo and Ana Paula Duarte
Molecules 2021, 26(5), 1397; https://doi.org/10.3390/molecules26051397 - 05 Mar 2021
Cited by 14 | Viewed by 6353
Abstract
The consumption of new psychoactive substances (NPSs) has been increasing, and this problem affects several countries worldwide. There is a class of NPSs of natural origin, consisting of plants and fungi, which have a wide range of alkaloids, responsible for causing relaxing, stimulating [...] Read more.
The consumption of new psychoactive substances (NPSs) has been increasing, and this problem affects several countries worldwide. There is a class of NPSs of natural origin, consisting of plants and fungi, which have a wide range of alkaloids, responsible for causing relaxing, stimulating or hallucinogenic effects. The consumption of some of these substances is prompted by religious beliefs and cultural reasons, making the legislation very variable or even ambiguous. However, the abusive consumption of these substances can present an enormous risk to the health of the individuals, since their metabolism and effects are not yet fully known. Additionally, NPSs are widely spread over the internet, and their appearance is very fast, which requires the development of sophisticated analytical methodologies, capable of detecting these compounds. Thus, the objective of this work is to review the toxicological aspects, traditional use/therapeutic potential and the analytical methods developed in biological matrices in twelve plant specimens (Areca catechu, Argyreia nervosa, Ayahuasca, Catha edulis, Datura stramonium, Lophophora williamsii, Mandragora officinarum, Mitragyna speciosa, Piper methysticum Forst, Psilocybe, Salvia divinorum and Tabernanthe iboga). Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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38 pages, 1470 KiB  
Review
Potential Therapeutic Targets of Quercetin, a Plant Flavonol, and Its Role in the Therapy of Various Types of Cancer through the Modulation of Various Cell Signaling Pathways
by Saleh A. Almatroodi, Mohammed A. Alsahli, Ahmad Almatroudi, Amit Kumar Verma, Abdulaziz Aloliqi, Khaled S. Allemailem, Amjad Ali Khan and Arshad Husain Rahmani
Molecules 2021, 26(5), 1315; https://doi.org/10.3390/molecules26051315 - 01 Mar 2021
Cited by 77 | Viewed by 7022
Abstract
Polyphenolic flavonoids are considered natural, non-toxic chemopreventers, which are most commonly derived from plants, fruits, and vegetables. Most of these polyphenolics exhibit remarkable antioxidant, anti-inflammatory, and anticancer properties. Quercetin (Qu) is a chief representative of these polyphenolic compounds, which exhibits excellent antioxidant and [...] Read more.
Polyphenolic flavonoids are considered natural, non-toxic chemopreventers, which are most commonly derived from plants, fruits, and vegetables. Most of these polyphenolics exhibit remarkable antioxidant, anti-inflammatory, and anticancer properties. Quercetin (Qu) is a chief representative of these polyphenolic compounds, which exhibits excellent antioxidant and anticancer potential, and has attracted the attention of researchers working in the area of cancer biology. Qu can regulate numerous tumor-related activities, such as oxidative stress, angiogenesis, cell cycle, tumor necrosis factor, proliferation, apoptosis, and metastasis. The anticancer properties of Qu mainly occur through the modulation of vascular endothelial growth factor (VEGF), apoptosis, phosphatidyl inositol-3-kinase (P13K)/Akt (proteinase-kinase B)/mTOR (mammalian target of rapamycin), MAPK (mitogen activated protein kinase)/ERK1/2 (extracellular signal-regulated kinase 1/2), and Wnt/β-catenin signaling pathways. The anticancer potential of Qu is documented in numerous in vivo and in vitro studies, involving several animal models and cell lines. Remarkably, this phytochemical possesses toxic activities against cancerous cells only, with limited toxic effects on normal cells. In this review, we present extensive research investigations aimed to discuss the therapeutic potential of Qu in the management of different types of cancers. The anticancer potential of Qu is specifically discussed by focusing its ability to target specific molecular signaling, such as p53, epidermal growth factor receptor (EGFR), VEGF, signal transducer and activator of transcription (STAT), PI3K/Akt, and nuclear factor kappa B (NF-κB) pathways. The anticancer potential of Qu has gained remarkable interest, but the exact mechanism of its action remains unclear. However, this natural compound has great pharmacological potential; it is now believed to be a complementary—or alternative—medicine for the prevention and treatment of different cancers. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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21 pages, 2070 KiB  
Review
Transdermal Delivery Systems of Natural Products Applied to Skin Therapy and Care
by Ying-Chen Cheng, Tzong Shiun Li, Hong Lin Su, Po Chun Lee and Hui-Min David Wang
Molecules 2020, 25(21), 5051; https://doi.org/10.3390/molecules25215051 - 30 Oct 2020
Cited by 35 | Viewed by 4448
Abstract
Natural products are favored because of their non-toxicity, low irritants, and market reacceptance. We collected examples, according to ancient wisdom, of natural products to be applied in transdermal delivery. A transdermal delivery system, including different types of agents, such as ointments, patches, and [...] Read more.
Natural products are favored because of their non-toxicity, low irritants, and market reacceptance. We collected examples, according to ancient wisdom, of natural products to be applied in transdermal delivery. A transdermal delivery system, including different types of agents, such as ointments, patches, and gels, has long been used for skin concerns. In recent years, many novel transdermal applications, such as nanoemulsions, liposomes, lipid nanoparticles, and microneedles, have been reported. Nanosized drug delivery systems are widely applied in natural product deliveries. Nanosized materials notably enhance bioavailability and solubility, and are reported to improve the transdermal permeation of many substances compared with conventional topical formulations. Natural products have been made into nanosized biomaterials in order to enhance the penetration effect. Before introducing the novel transdermal applications of natural products, we present traditional methods within this article. The descriptions of novel transdermal applications are classified into three parts: liposomes, emulsions, and lipid nanoparticles. Each section describes cases that are related to promising natural product transdermal use. Finally, we summarize the outcomes of various studies on novel transdermal agents applied to skin treatments. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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13 pages, 2002 KiB  
Technical Note
Synergizing Off-Target Predictions for In Silico Insights of CENH3 Knockout in Cannabis through CRISPR/Cas
by Mohsen Hesami, Mohsen Yoosefzadeh Najafabadi, Kristian Adamek, Davoud Torkamaneh and Andrew Maxwell Phineas Jones
Molecules 2021, 26(7), 2053; https://doi.org/10.3390/molecules26072053 - 03 Apr 2021
Cited by 28 | Viewed by 4143
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-mediated genome editing system has recently been used for haploid production in plants. Haploid induction using the CRISPR/Cas system represents an attractive approach in cannabis, an economically important industrial, recreational, and medicinal plant. However, the CRISPR [...] Read more.
The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-mediated genome editing system has recently been used for haploid production in plants. Haploid induction using the CRISPR/Cas system represents an attractive approach in cannabis, an economically important industrial, recreational, and medicinal plant. However, the CRISPR system requires the design of precise (on-target) single-guide RNA (sgRNA). Therefore, it is essential to predict off-target activity of the designed sgRNAs to avoid unexpected outcomes. The current study is aimed to assess the predictive ability of three machine learning (ML) algorithms (radial basis function (RBF), support vector machine (SVM), and random forest (RF)) alongside the ensemble-bagging (E-B) strategy by synergizing MIT and cutting frequency determination (CFD) scores to predict sgRNA off-target activity through in silico targeting a histone H3-like centromeric protein, HTR12, in cannabis. The RF algorithm exhibited the highest precision, recall, and F-measure compared to all the tested individual algorithms with values of 0.61, 0.64, and 0.62, respectively. We then used the RF algorithm as a meta-classifier for the E-B method, which led to an increased precision with an F-measure of 0.62 and 0.66, respectively. The E-B algorithm had the highest area under the precision recall curves (AUC-PRC; 0.74) and area under the receiver operating characteristic (ROC) curves (AUC-ROC; 0.71), displaying the success of using E-B as one of the common ensemble strategies. This study constitutes a foundational resource of utilizing ML models to predict gRNA off-target activities in cannabis. Full article
(This article belongs to the Special Issue Natural Products: Therapeutic Properties and Beyond)
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