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Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays

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

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 19651

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Special Issue Editors

Prof. Dr. Brigida D'Abrosca

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Guest Editor

Dipartimento di Scienze e Tecnologie Ambientali Biologiche e Farmaceutiche–DiSTABiF, Università degli Studi della Campania “Luigi Vanvitelli”, via Vivaldi 43, I-81100 Caserta, Italy
Interests: natural product chemistry; NMR; structural elucidation; metabolomic; bioactive compounds; allelopathy; antimicrobial assay; NMR-metabolic profiling

Prof. Dr. Francisco A. Macias

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Guest Editor

Universidad de Cadiz, Cadiz, Spain
Interests: allelopathy; natural product chemistry; plant–plant interactions; plant–microorganisms interactions; bioassays; bioaguided isolation of bioactive compounds; structure–activity relationships (SAR) studies; structural elucidation; synthesis
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Special Issue Information

Dear Colleagues,

Nature represents a powerful source of new compounds, most of which are bioactive metabolites. In particular, plant and marine organisms produce the majority of small molecules used as direct drugs or as lead compounds for synthetic or semisynthetic compounds based on natural products. So, natural product chemistry is a research area in constant expansion based on the continuous development of new extraction methods, chromatographic techniques, as well as the use of multidimensional NMR experiments widely used to contribute de novo identifications of small compounds. The final goal of natural product research is the assessment of bioactivity for new or known compounds in order to evaluate small molecules as potential antimicrobial, antiviral, antiproliferative, or antioxidant agents.

Contributions for this Special Issue “Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation, and Biological Assays“, both in the form of original research and review articles, may cover all aspects of natural products chemistry, including the extraction of small molecules, the purification and structural characterization of new compounds, as well as the in vitro and in vivo evaluation of biological activities of new isolated compounds and their analogues or known metabolites.

Prof. Dr. Brigida D'Abrosca
Prof. Dr. Francisco A. Macias
Guest Editors

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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
phenols
terpenoids
alkaloids
extraction procedure
chromatographyc tecniques
NMR
structure elucidation
phytochemical analysis
bioactivity assesment

Published Papers (5 papers)

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Research

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10 pages, 1508 KiB

Open AccessArticle

Anti-Inflammatory Effect of Charantadiol A, Isolated from Wild Bitter Melon Leaf, on Heat-Inactivated Porphyromonas gingivalis-Stimulated THP-1 Monocytes and a Periodontitis Mouse Model

by Tzung-Hsun Tsai, Chi-I Chang, Ya-Ling Hung, Wen-Cheng Huang, Hsiang Chang, Yueh-Hsiung Kuo, Jong-Ho Chyuan, Lu-Te Chuang and Po-Jung Tsai

Molecules 2021, 26(18), 5651; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26185651 - 17 Sep 2021

Cited by 1 | Viewed by 1744

Abstract

Porphyromonas gingivalis has been identified as one of the major periodontal pathogens. Activity-directed fractionation and purification processes were employed to identify bioactive compounds from bitter melon leaf. Ethanolic extract of bitter melon leaf was separated into five subfractions by open column chromatography. Subfraction-5-3 significantly inhibited P. gingivalis-induced interleukin (IL)-8 and IL-6 productions in human monocytic THP-1 cells and then was subjected to separation and purification by using different chromatographic methods. Consequently, 5β,19-epoxycucurbita-6,23(E),25(26)-triene-3β,19(R)-diol (charantadiol A) was identified and isolated from the subfraction-5-3. Charantadiol A effectively reduced P. gingivalis-induced IL-6 and IL-8 productions and triggered receptors expressed on myeloid cells (TREM)-1 mRNA level of THP-1 cells. In a separate study, charantadiol A significantly suppressed P. gingivalis-stimulated IL-6 and tumor necrosis factor-α mRNA levels in gingival tissues of mice, confirming the inhibitory effect against P. gingivalis-induced periodontal inflammation. Thus, charantadiol A is a potential anti-inflammatory agent for modulating P. gingivalis-induced inflammation. Full article

(This article belongs to the Special Issue Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays)

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16 pages, 2440 KiB

Open AccessFeature PaperArticle

Chemical Characterization and Anti-HIV-1 Activity Assessment of Iridoids and Flavonols from Scrophularia trifoliata

by Francesca Guzzo, Rosita Russo, Cinzia Sanna, Odeta Celaj, Alessia Caredda, Angela Corona, Enzo Tramontano, Antonio Fiorentino, Francesca Esposito and Brigida D’Abrosca

Molecules 2021, 26(16), 4777; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26164777 - 06 Aug 2021

Cited by 8 | Viewed by 1992

Abstract

Plants are the everlasting source of a wide spectrum of specialized metabolites, characterized by wide variability in term of chemical structures and different biological properties such antiviral activity. In the search for novel antiviral agents against Human Immunodeficiency Virus type 1 (HIV-1) from plants, the phytochemical investigation of Scrophularia trifoliata L. led us to isolate and characterize four flavonols glycosides along with nine iridoid glycosides, two of them, 5 and 13, described for the first time. In the present study, we investigated, for the first time, the contents of a methanol extract of S. trifoliata leaves, in order to explore the potential antiviral activity against HIV-1. The antiviral activity was evaluated in biochemical assays for the inhibition of HIV-1Reverse Transcriptase (RT)-associated Ribonuclease H (RNase H) activity and HIV-1 Integrase (IN). Three isolated flavonoids, rutin, kaempferol-7-O-rhamnosyl-3-O-glucopyranoside, and kaempferol-3-O-glucopyranoside, 8–10, inhibited specifically the HIV-1 IN activity at submicromolar concentration, with the latter being the most potent, showing an IC₅₀ value of 24 nM. Full article

(This article belongs to the Special Issue Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays)

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15 pages, 2163 KiB

Open AccessArticle

New Antiproliferative Triflavanone from Thymelaea hirsuta—Isolation, Structure Elucidation and Molecular Docking Studies

by Sameh S. Elhady, Reda F. A. Abdelhameed, Mayada M. El-Ayouty, Amany K. Ibrahim, Eman S. Habib, Mohamed S. Elgawish, Hashim A. Hassanean, Martin K. Safo, Mohamed S. Nafie and Safwat A. Ahmed

Molecules 2021, 26(3), 739; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26030739 - 31 Jan 2021

Cited by 8 | Viewed by 2957

Abstract

In this study isolates from Thymelaea hirsuta, a wild plant from the Sinai Peninsula of Egypt, were identified and their selective cytotoxicity levels were evaluated. Phytochemical examination of the ethyl acetate (EtOAc) fraction of the methanolic (MeOH) extract of the plant led to the isolation of a new triflavanone compound (1), in addition to the isolation of nine previously reported compounds. These included five dicoumarinyl ethers found in Thymelaea: daphnoretin methyl ether (2), rutamontine (3), neodaphnoretin (4), acetyldaphnoretin (5), and edgeworthin (6); two flavonoids: genkwanin (7) and trans-tiliroside (8); p-hydroxy benzoic acid (9) and β sitosterol glucoside (10). Eight of the isolated compounds were tested for in vitro cytotoxicity against Vero and HepG2 cell lines using a sulforhodamine-B (SRB) assay. Compounds 1, 2 and 5 exhibited remarkable cytotoxic activities against HepG2 cells, with IC₅₀ values of 8.6, 12.3 and 9.4 μM, respectively, yet these compounds exhibited non-toxic activities against the Vero cells. Additionally, compound 1 further exhibited promising cytotoxic activity against both MCF-7 and HCT-116 cells, with IC₅₀ values of 4.26 and 9.6 μM, respectively. Compound 1 significantly stimulated apoptotic breast cancer cell death, resulting in a 14.97-fold increase and arresting 40.57% of the cell population at the Pre-G1 stage of the cell cycle. Finally, its apoptosis-inducing activity was further validated through activation of BAX and caspase-9, and inhibition of BCL2 levels. In silico molecular docking experiments revealed a good binding mode profile of the isolates towards Ras activation/pathway mitogen-activated protein kinase (Ras/MAPK); a common molecular pathway in the development and progression of liver tumors. Full article

(This article belongs to the Special Issue Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays)

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18 pages, 3147 KiB

Open AccessArticle

Bio-Guided Isolation of Acetogenins from Annona cherimola Deciduous Leaves: Production of Nanocarriers to Boost the Bioavailability Properties

by Maria Teresa Gutiérrez, Alexandra G. Durán, Francisco J. R. Mejías, José M. G. Molinillo, Diego Megias, Manuel M. Valdivia and Francisco A. Macías

Molecules 2020, 25(20), 4861; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25204861 - 21 Oct 2020

Cited by 12 | Viewed by 3173

Abstract

Annonaceous acetogenins (ACGs) are lipophilic polyketides isolated exclusively from Annonaceae. They are considered to be amongst the most potent antitumor compounds. Nevertheless, their applications are limited by their poor solubility. The isolation of ACGs from Annona cherimola leaves, an agricultural waste, has not been reported to date. Molvizarin (1) cherimolin-1 (2), motrilin (3), annonacin (4) and annonisin (5) are isolated for the first time from A. cherimola deciduous leaves. Annonacin was found to be four- and two-times more potent in tumoral cells (HeLa, 23.6% live cells; IGROV-1, 40.8% live cells for 24 h) than in HEK-293 at 50 µM (24 h, 87.2% live cells). Supramolecular polymer micelles (SMPMs) were synthesized to encapsulate the major ACG isolated, annonacin, in order to improve its solubility in aqueous media. The bioavailability of this compound was increased by a factor of 13 in a simulated human digestive system when compared with free annonacin and an encapsulation efficiency of 35% was achieved. In addition, the cytotoxic activity of SMPMs that hosted annonacin (100 µM, 24 h, 5.8% live cells) was increased compared with free annonacin in water (100 µM, 24 h, 92% live cells). These results highlight the use of by-products of A. cherimola, and their pure compounds, as a promising source of anticancer agents. The use of SMPMs as nanocarriers of ACGs could be an alternative for their application in food field as nutraceutical to enhance the administration and efficacy. Full article

(This article belongs to the Special Issue Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays)

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Review

Jump to: Research

18 pages, 1018 KiB

Open AccessReview

Alkaloids Used as Medicines: Structural Phytochemistry Meets Biodiversity—An Update and Forward Look

by Michael Heinrich, Jeffrey Mah and Vafa Amirkia

Molecules 2021, 26(7), 1836; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26071836 - 25 Mar 2021

Cited by 99 | Viewed by 8947

Abstract

Selecting candidates for drug developments using computational design and empirical rules has resulted in a broad discussion about their success. In a previous study, we had shown that a species’ abundance [as expressed by the GBIF (Global Biodiversity Information Facility)] dataset is a core determinant for the development of a natural product into a medicine. Our overarching aim is to understand the unique requirements for natural product-based drug development. Web of Science was queried for research on alkaloids in combination with plant systematics/taxonomy. All alkaloids containing species demonstrated an average increase of 8.66 in GBIF occurrences between 2014 and 2020. Medicinal Species with alkaloids show higher abundance compared to non-medicinal alkaloids, often linked also to cultivation. Alkaloids with high biodiversity are often simple alkaloids found in multiple species with the presence of ’driver species‘ and are more likely to be included in early-stage drug development compared to ‘rare’ alkaloids. Similarly, the success of an alkaloid containing species as a food supplement (‘botanical’) is linked to its abundance. GBIF is a useful tool for assessing the druggability of a compound from a certain source species. The success of any development programme from natural sources must take sustainable sourcing into account right from the start. Full article

(This article belongs to the Special Issue Trends in Bioactive Natural Products Research: Isolation, Structural Elucidation and Biological Assays)

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