Nature-Inspired Scaffolds in Medicinal Chemistry: An Old Push for Modern Drug Discovery

A special issue of Chemistry (ISSN 2624-8549). This special issue belongs to the section "Biological and Natural Products".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 19639

Special Issue Editors


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Guest Editor Assistant
CBIOS Research Center for Biosciences and Health Technologies, Lusófona University, Campo Grande 376, 1749-024 Lisbon, Portugal
Interests: medicinal chemistry; natural products; organic chemistry

Special Issue Information

Dear Colleagues,

Natural products could be considered the first form of inspiration for the generation of pharmaceutical derivatives. They were used in ancient times as sources of active ingredients for the management and treatment of various diseases and conditions, becoming the bedrock of traditional medicine, especially in the poorest countries, where more expensive alternatives are not available. In recent years, thanks to the sensitization to nature-related thematics and the advancements in screening, isolation, characterization and optimization methodologies, we have witnessed a renaissance of natural products, whose sources are finally considered as both resources to valorize as well as treasures to preserve. For this reason, natural products are being increasingly used for modern drug design and discovery, resulting in extensive efforts in pharmaceutical fields and satisfactory outcomes concerning disorders still lacking effective medication. This Special Issue calls for researchers to contribute and share their work concerning:

  1. Original research/review articles concerning the extraction of metabolites from plants, characterization of new identified products and semi-synthesis of potentially bioactive compounds with nature-derived scaffolds;
  2. Original research/review articles concerning the bioactivity of natural/semisynthetic compounds against relevant disease conditions and how their therapeutic effect is exerted;
  3. Original research/ review articles concerning alternative synthetic ways to obtain naturally occurring bioactive molecules or simplified/optimized analogues, with evident advantages with respect to natural matrix integrity and overall yield;
  4. Original research/ review articles concerning the incorporation of biologically active natural/semisynthetic compounds in polymeric matrixes for the preparation of new bioactive materials suitable for food or surface preservatives, as well as human medication devices;
  5. Pre-clinical or clinical studies concerning bioactive natural/semisynthetic compounds regarding their activity and toxicology profiles.

Dr. Patrícia Rijo
Guest Editor

Dr. Salvatore Princiotto
Guest Editor Assistant

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Keywords

  • drug discovery
  • natural products
  • bioactive compounds

Published Papers (8 papers)

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Research

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15 pages, 1777 KiB  
Article
Achillea fragrantissima Essential Oil, Wild Grown in Saudi Arabia and Egypt: Detailed Comparative Chemical Profiling, and Evaluation of Allelopathic, Antioxidant, and Antibacterial Activities
by Ahmed M. Abd-ElGawad, Rania F. Ahmed, Abdelsamed I. Elshamy, Eslam G. Sadek, Abdulaziz M. Assaeed, Giuliano Bonanomi, Abd El-Nasser G. El Gendy and Yasser A. El-Amier
Chemistry 2023, 5(4), 2347-2361; https://doi.org/10.3390/chemistry5040155 - 22 Oct 2023
Viewed by 1131
Abstract
One of the biologically beneficial oils against many ailments is Achillea fragrantissima essential oil (EO). The current study focused on the comprehensive comparative chemical characterization of A. fragrantissima EOs, which were gathered from Saudi Arabia and Egypt, as well as evaluation of their [...] Read more.
One of the biologically beneficial oils against many ailments is Achillea fragrantissima essential oil (EO). The current study focused on the comprehensive comparative chemical characterization of A. fragrantissima EOs, which were gathered from Saudi Arabia and Egypt, as well as evaluation of their allelopathic, antioxidant, and antibacterial functions. With a respective total oil mass of 96.9% and 96.1%, 40 compounds were found in the EOs from Saudi Arabia (38 compounds) and Egypt (26 compounds). Terpenes represented the main constituents including mono- (52.6% and 75.4% from Saudi Arabia and Egypt, respectively) and sesquiterpenoids (42.1% and 19.7%, respectively). The α-thujone (12.0%), myrcenyl acetate (10.3%), alloaromadendrene oxide-(1) (5.9%), artemisia ketone (4.9%), β-thujone (4.7%), lavandulol (4.2%), and santolina alcohol (4.0%) represented the main components of the overall oil of the Saudi Arabian plant-derived EO. However, the main constituents of the EO of the Egyptian plant were 4-terpineol (17.4%), myrcenyl acetate (9.1%), artemisia ketone (9.0%), α-thujone (8.6%), yomogi alcohol (6.2%), santolina alcohol (6.2%), and β-thujone (5.8%). The chemometric analysis exhibited a strong association between the two EOs from Saudi Arabia and Egypt in addition to the samples collected from Jordan. The Saudi and Egyptian A. fragrantissima’ EOs were found to have significant allelopathic potencies against the weed C. murale. The seed germination, seedling shoot growth, and root growth of C. murale were all reduced by the EO of the Saudi ecospecies by 79.9, 56.7, and 68.6%, respectively, with IC50 values of 66.5, 68.0, and 69.2 µL L−1, respectively. The two oils from Saudi Arabia and Egypt exhibited potent antioxidant activity against the DPPH free radicals, with IC50 values of 30.94 and 28.72 mg/L, respectively. In addition, the two oils from Saudi Arabia and Egypt exhibited strong abilities to scavenge ABTS radicals with respective IC50 values of 39.02 and 37.13 mg/L. Additionally, the two EOs showed a much higher antibacterial activity than the antibiotics tested against all bacterial strains, with the exception of Enterobacter cloacae. The two oils exhibited antibacterial activity against the examined strains, except Bacillus subtilis and Salmonella typhimurium, for which the Egyptian species shown greater inhibition. The results revealed that Escherichia coli and Staphylococcus epidermidis were more sensitive, while Enterobacter cloacae was more resistant. Full article
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16 pages, 3417 KiB  
Article
Gas Chromatography–Mass Spectrometry Chemical Profiling and Radical Scavenging Potential of Sesquiterpene-Rich Essential Oil of Polygonum equisetiforme Sm.: In Silico Study on Hematopoietic Cell Kinase (Hck) and Human Peroxiredoxin 5
by Ahmed M. Abd-ElGawad, Rania F. Ahmed, Ahmed F. Essa, Abd El-Nasser G. El Gendy, Samah A. El-Newary, Abdelsamed I. Elshamy, Tushar C. Sarker and Yasser A. El-Amier
Chemistry 2023, 5(4), 2257-2272; https://doi.org/10.3390/chemistry5040151 - 19 Oct 2023
Cited by 1 | Viewed by 1055
Abstract
Essential oils (EOs) are advised by traditional medical systems for the treatment of a variety of disorders worldwide. In many ancient medical systems around the world, Polygonum herbs have been employed as remedies including P. equisetiforme Sm. The EO profile of P. equisetiforme [...] Read more.
Essential oils (EOs) are advised by traditional medical systems for the treatment of a variety of disorders worldwide. In many ancient medical systems around the world, Polygonum herbs have been employed as remedies including P. equisetiforme Sm. The EO profile of P. equisetiforme and its bioactivities have yet to be discussed in depth. As a result, the current study aims to investigate the chemical profile and free radical scavenging capacity of P. equisetiforme EO. Hydrodistillation was used to obtain the EO from P. equisetiforme, and gas chromatography–mass spectrometry (GC-MS) was used for analysis. A total of forty-three compounds, including terpenes and sesquiterpenes as the main components (76.13% and 69.06%, respectively), were identified in the oil using the GC-MS analysis. The main constituents of the oil were hexahydrofarnesyl acetone (29.45%), 7-epi-selinene (14.45%), isospathulenol (8.35%), and n-docosane (6.79%). The chemosystematic significance of the plant was established via multivariate assessing, comprising principal component analysis (PCA), hierarchical clustering, and constellation plot, of the EO principal components of the various Polygonum plants. The P. equisetiforme exhibited different associations with the studied Polygonum spp. Then, the scavenging of the free radicals 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was used to evaluate the radical scavenging abilities of EO compared with those of vitamin C, a reference antioxidant. P. equisetiforme EO exhibited the scavenging capacity of the DPPH and the ABTS free radical with respective IC50 values of 470.01 and 113.74 mg L−1 compared with vitamin C, and with IC50 values of 39.06 and 26.09 mg L−1, respectively. The in silico studies revealed that the oxygenated sesquiterpenes, especially ar-turmerone, hexahydrofarnesyl acetone, and 5E,9E-farnesyl acetone, exhibited the best fitting with hematopoietic cell kinase (Hck) and human Peroxiredoxin 5 proteins with ΔG values of −6.14 and −4.93, −6.83 and −5.34, and −7.08 and −5.47 kcal/mol, respectively. The major components’ combined or individual effects may be responsible for the antioxidant properties. Therefore, additional extensive studies are advised to characterize the essential compounds as radical scavenger agents, either individually or in combination. Full article
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13 pages, 4396 KiB  
Article
Molecular Modeling Based on Time-Dependent Density Functional Theory (TD-DFT) Applied to the UV-Vis Spectra of Natural Compounds
by João Otávio Anhaia-Machado, Artur Caminero Gomes Soares, Claudinéia Aparecida Sales de Oliveira Pinto, Andres Ignacio Ávila Barrera, André Rolim Baby and Gustavo Henrique Goulart Trossini
Chemistry 2023, 5(1), 41-53; https://doi.org/10.3390/chemistry5010004 - 28 Dec 2022
Cited by 4 | Viewed by 2629
Abstract
As diseases caused by solar radiation have gained great prominence, several methods to prevent them have been developed. Among the most common, the use of sunscreens is customary and accessible. The application of theoretical methods has helped to design new compounds with therapeutic [...] Read more.
As diseases caused by solar radiation have gained great prominence, several methods to prevent them have been developed. Among the most common, the use of sunscreens is customary and accessible. The application of theoretical methods has helped to design new compounds with therapeutic and protective functions. Natural compounds with described photoprotective potential properties (3-O-methylquercetin, gallic acid, aloin, catechin, quercetin, and resveratrol) were selected to perform theoretical studies. Computational methods were applied to predict their absorption spectra, using DFT and TD-DFT methods with functional B3LYP/6−311+g(d,p) basis sets and methanol (IEFPCM) as a solvent. The main electronic transitions of the compounds were evaluated by observing whether the differences in HOMO and LUMO energies that absorb in the UV range are UVA (320–400 nm), UVB (290–320 nm), or UVC (100–290 nm). Experimental validation was carried out for EMC, quercetin, and resveratrol, demonstrating the consistency of the computational method. Results obtained suggest that resveratrol is a candidate for use in sunscreens. The study provided relevant information about the in silico predictive power of natural molecules with the potential for use as photoprotective adjuvants, which may result in fewer time and resource expenditures in the search for photoprotective compounds. Full article
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14 pages, 2271 KiB  
Article
Comparative Analysis of the Chemical Composition and Antimicrobial Activity of Four Moroccan North Middle Atlas Medicinal Plants’ Essential Oils: Rosmarinus officinalis L., Mentha pulegium L., Salvia officinalis L., and Thymus zygis subsp. gracilis (Boiss.) R. Morales
by Aman Allah Gourich, Noureddine Bencheikh, Mohamed Bouhrim, Mohamed Regragui, Rachid Rhafouri, Aziz Drioiche, Ayoub Asbabou, Firdaous Remok, Aicha Mouradi, Mohamed Addi, Christophe Hano and Touriya Zair
Chemistry 2022, 4(4), 1775-1788; https://doi.org/10.3390/chemistry4040115 - 19 Dec 2022
Cited by 5 | Viewed by 2739
Abstract
Medicinal plants represent an inexhaustible source of traditional and effective remedies thanks to the various active ingredients they contain. Secondary metabolites present in plant extracts, such as essential oils (EO), have remarkable pharmacological properties, including antimicrobial effects. Here, the chemical composition and antimicrobial [...] Read more.
Medicinal plants represent an inexhaustible source of traditional and effective remedies thanks to the various active ingredients they contain. Secondary metabolites present in plant extracts, such as essential oils (EO), have remarkable pharmacological properties, including antimicrobial effects. Here, the chemical composition and antimicrobial effects of four Moroccan medicinal plants, Rosmarinus officinalis L. (R. officinalis), Mentha pulegium L. (M. pulegium), Salvia officinalis L. (S. officinalis), and Thymus zygis subsp. gracilis (Boiss.) R. Morales (T. zygis), traditionally used in Morocco to treat microbial infections, were addressed. EO were extracted using the hydrodistillation method, and analyzed by gas chromatography coupled with mass spectrometry (GC/MS). EO yields were of 3.64 ± 0.12, 3.53 ± 0.06, 2.48 ± 0.06, and 2.34 ± 0.08%, respectively, for M. pulegium, R. officinalis, S. officinalis, and T. zygis. The main bioactive components present in these EO were piperitenone (32.9%) and pulegone (32.8%) for M. pulegium, 1,8-cineol (43.8%) and camphor (18.7%) for R. officinalis, 1,8-cineole (16.8%) and trans-thujone (15.9%) for S. officinalis, and thymol (36.4%), carvacrol (24.1%) and cymene (23.5%) for T. zygis. These EO showed, according to the results of their antimicrobial activities, good effectiveness against bacteria and fungi. Moreover, the T. zygis EO showed the most potent activity against all bacteria studied, while that of R. officinalis, M. pulegium, and S. officinalis showed moderate activity against the Enterobacter cloacae of Streptococcus agalactiae and Escherichia coli. The antifungal activity tests revealed a strong antifungal activity for the T. zygis EO and a moderate activity for the S. officinalis EO. On the other hand, the EO of R. officinalis, and M. pulegium were found to be inactive at the doses used against the selected strains. In conclusion, our results show that the medicinal plants studied contain biologically active molecules with antimicrobial effects. They can replace synthesized molecules, especially in the formulation of additives, and for therapeutic, cosmetic, and food-processing purposes. Full article
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12 pages, 9110 KiB  
Article
Promising Anticancer Activity of β-Carboline Derivatives: Design, Synthesis, and Pharmacological Evaluation
by Ravindra Kumar Chourasiya, Ram Kishore Agrawal and Ankur Vaidya
Chemistry 2022, 4(4), 1395-1406; https://doi.org/10.3390/chemistry4040091 - 28 Oct 2022
Cited by 2 | Viewed by 1619
Abstract
β-carboline consists of a pyridine ring fused to an indole skeleton; it possesses numerous pharmacological activities, including anticancer. Previously, we reported a satisfactory 2D and 3D QSAR study on β-carboline derivatives. Based on QSAR studies, we designed, synthesized, characterized, and screened fourteen β-carboline [...] Read more.
β-carboline consists of a pyridine ring fused to an indole skeleton; it possesses numerous pharmacological activities, including anticancer. Previously, we reported a satisfactory 2D and 3D QSAR study on β-carboline derivatives. Based on QSAR studies, we designed, synthesized, characterized, and screened fourteen β-carboline derivatives for anticancer activity. Eleven of them demonstrated potent anticancer activity against both liver (HepG2) and adenocarcinoma (A549) cell lines. Compound 1-(N, N-dimethylbenzenamine)-3-(4-(p-tolylmethanimine)-5-thio-1, 2, 4-triazol-3-yl) β-carboline (9) was found to be most potent against both cancer cell lines and equipotent towards standard drug Adriamycin. Compounds 1-(p-tolyl)-3-(4-(p-(iminomethyl)-N, N-dimethylbenzenamine) -5-thio-1, 2, 4-triazol-3-yl) β-carboline (4) and 1-(N, N-dimethylbenzenamine)-3-(4-(m-tolylmethanimine)-5-thio-1, 2, 4-triazol-3-yl) β-carboline (10) were found to be 7 to 10 times less potent as compared to Adriamycin against the HepG2 cell line. Molecular docking was also performed with the Glide docking program to explore the binding mode between the synthesized β-carboline derivatives and the receptor CDK2 [1AQ1] protein. Full article
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Review

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22 pages, 2993 KiB  
Review
An Update on Phytochemicals in Redox Homeostasis: “Virtuous or Evil” in Cancer Chemoprevention?
by Homa Fatma, Mohd Jameel and Hifzur R. Siddique
Chemistry 2023, 5(1), 201-222; https://doi.org/10.3390/chemistry5010017 - 04 Feb 2023
Cited by 8 | Viewed by 2003
Abstract
Redox homeostasis, a dynamic process ensuring a balance between cellular oxidizing and reducing reactions, is crucial for maintaining healthy cellular physiology and regulating many biological processes, requiring continuous monitoring and fine-tuning. Reactive species play a critical role in intra/intercellular signaling, and each cell [...] Read more.
Redox homeostasis, a dynamic process ensuring a balance between cellular oxidizing and reducing reactions, is crucial for maintaining healthy cellular physiology and regulating many biological processes, requiring continuous monitoring and fine-tuning. Reactive species play a critical role in intra/intercellular signaling, and each cell has a specific system guarding cellular redox homeostasis. ROS signaling and oxidative stress are involved in cancer initiation and progression. However, the generation of reactive species beyond the threshold level inside the tumor microenvironment is considered one of the therapeutic approaches. Various studies have shown that some phytochemicals can target the redox homeostasis of the tumor microenvironment. Recent advances have focused on developing and introducing phytochemical interventions as favorable therapeutic options against cancer. However, studies have also suggested the “virtuous” and “evil” impacts of phytochemicals. Some phytochemicals enhance therapeutic efficacy by promoting intracellular oxidant accumulation. However, under certain conditions, some phytochemicals may harm the cellular microenvironment to promote cancer and tend to target different pathways for cancer initiation and development instead of targeting redox homeostasis. In this context, this review is focused on providing an overall understanding of redox homeostasis and intends to highlight the potential positive and negative impacts of phytochemicals in redox homeostasis and disease development. We also discuss the recent nanotechnology-based advancements in combating cancer development. Full article
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18 pages, 2300 KiB  
Review
Diverse Biological Activities of 1,3,4-Thiadiazole Scaffold
by Tulika Anthwal, Sarvesh Paliwal and Sumitra Nain
Chemistry 2022, 4(4), 1654-1671; https://doi.org/10.3390/chemistry4040107 - 06 Dec 2022
Cited by 19 | Viewed by 3420
Abstract
The chemistry of 1,3,4-thiadiazole is one of the most interesting scaffolds for synthesizing new drug molecules due to their numerous pharmacological activities. Several modifications in the thiadiazole ring have been made, proving it to be more potent and highly effective with a less [...] Read more.
The chemistry of 1,3,4-thiadiazole is one of the most interesting scaffolds for synthesizing new drug molecules due to their numerous pharmacological activities. Several modifications in the thiadiazole ring have been made, proving it to be more potent and highly effective with a less toxic scaffold for various biological activities. There are several marketed drugs containing 1,3,4-thiadiazole ring in their structure. In this review article, we have tried to compile the newly synthesized 1,3,4-thiadiazole derivatives possessing important pharmaceutical significance since 2014. Full article
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32 pages, 4737 KiB  
Review
Traditional Uses, Phytochemical Composition, Pharmacological Properties, and the Biodiscovery Potential of the Genus Cirsium
by Gaurav Aggarwal, Gurpreet Kaur, Garima Bhardwaj, Vishal Mutreja, Harvinder Singh Sohal, Gulzar Ahmad Nayik, Anikesh Bhardwaj and Ajay Sharma
Chemistry 2022, 4(4), 1161-1192; https://doi.org/10.3390/chemistry4040079 - 30 Sep 2022
Cited by 6 | Viewed by 3709
Abstract
Medicinal plants are rich in phytochemicals, which have been used as a source of raw material in medicine since ancient times. Presently they are mostly used to treat Henoch–Schonlein purpura, hemoptysis, and bleeding. The manuscript covers the classification, traditional applications, phytochemistry, pharmacology, herbal [...] Read more.
Medicinal plants are rich in phytochemicals, which have been used as a source of raw material in medicine since ancient times. Presently they are mostly used to treat Henoch–Schonlein purpura, hemoptysis, and bleeding. The manuscript covers the classification, traditional applications, phytochemistry, pharmacology, herbal formulations, and patents of Cirsium. The main goal of this review is to impart recent information to facilitate future comprehensive research and use of Cirsium for the development of therapeutics. We investigated numerous databases PubMed, Google Scholar, Springer, Elsevier, Taylor and Francis imprints, and books on ethnopharmacology. The plants of the genus Cirsium of the family Asteraceae contain 350 species across the world. Phytochemical investigations showed that it contains flavonoids, phenols, polyacetylenes, and triterpenoids. The biological potential of this plant is contributed by these secondary metabolites. Cirsium plants are an excellent and harmless agent for the cure of liver diseases; therefore, they might be a good clinical option for the development of therapeutics for hepatic infections. The phytochemical studies of different Cirsium species and their renowned pharmacological activities could be exploited for pharmaceutic product development. Furthermore, studies are required on less known Cirsium species, particularly on the elucidation of the mode of action of their activities. Full article
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