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Special Issue "Isoflavonoids and Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Chemical Biology".

Deadline for manuscript submissions: closed (15 October 2020).

Special Issue Editor

Dr. Nawaf Al-Maharik
Website
Guest Editor
EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, UK
Interests: extraction and isolation of natural products from plants; synthesis of isoflavonoids; carbohydrate chemistry; fluorine chemistry; organotellurium and organosellenium chemistry

Special Issue Information

Dear Colleagues,

Flavonoids, a class of secondary metabolites with variable phenolic structures that have a C6-C3-C6 carbon framework, are found in fruits, vegetables, grains, nuts, onions, parsley, berries, bark, dark chocolate, and wine. The abundance of flavonoids combined with their low toxicity in comparison to other plant constituents allows them be consumed in larger quantities by animals and humans. They are now considered to be a crucial constituent in a variety of pharmaceutical, and cosmetic applications. This is due to their antioxidative, anti-inflammatory, antimutagenic, and anticarcinogenic properties, together with their ability to adjust key cellular enzyme functions. Research on flavonoids, their synthesis, isolation, characterization, and possible applications due to their health benefits, has received additional attention with the finding of their association with low cardiovascular mortality and the extrapolation of flavonoids to use as potential drugs for preventing chronic diseases.

The objective in assembling this special issue on flavonoids’ synthesis, isolation, identification, and characterization is to provide scientists from different disciplines, a perception into the scope and complexity of this multidimensional field.

There is no limitation on the topics as long as they fall in the course of flavonoids chemistry. Original articles as well as review articles on the below topics or other topics related to the chemistry of flavonoids would be welcomed.

Potential topics include but are not limited to the following:

  • Chemical and bio-synthesis of flavonoids and isoflavonoids
  • Extraction, isolation, identification and characterization of flavonoids, isoflavanoids, and neoflavanoids from plants and herbs using analytical chemistry methods
  • Comparisons of analytical methods for distinguishing types of flavonoids
  • Characterization of flavonoids, isoflavanoids, and neoflavanoids extracted from herbs and comparison studies on their effects and applications

Dr. Nawaf Al-Maharik
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 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

  • flavonoids
  • isoflavonoids
  • synthesis
  • biosynthesis
  • biological properties identification and quantification

Published Papers (4 papers)

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Research

Open AccessArticle
Overexpression of GbF3′5′H1 Provides a Potential to Improve the Content of Epicatechin and Gallocatechin
Molecules 2020, 25(20), 4836; https://doi.org/10.3390/molecules25204836 - 20 Oct 2020
Abstract
The flavonoids in Ginkgo biloba L. (ginkgo) have important medicinal uses due to their antioxidant, antitumor, and blood circulation-promoting effects. However, the genetic mechanisms underlying flavonoid biosynthesis in ginkgo remain elusive. Flavonoid 3′, 5′-hydroxylase (F3′5′H) is an important enzyme in flavonoid [...] Read more.
The flavonoids in Ginkgo biloba L. (ginkgo) have important medicinal uses due to their antioxidant, antitumor, and blood circulation-promoting effects. However, the genetic mechanisms underlying flavonoid biosynthesis in ginkgo remain elusive. Flavonoid 3′, 5′-hydroxylase (F3′5′H) is an important enzyme in flavonoid synthesis. We detected a novel differentially expressed GbF3′5′H1 gene homologous to the F3′5′H enzyme involved in the flavonoid synthesis pathway through transcriptome sequencing. In this study, we characterized this gene, performed an expression analysis, and heterologously overexpressed GbF3′5′H1 in Populus. Our results showed that GbF3′5′H1 is abundant in the leaf and highly expressed during April. We also found four metabolites closely related to flavonoid biosynthesis. Importantly, the contents of 4′,5-dihydroxy-7-glucosyloxyflavanone, epicatechin, and gallocatechin were significantly higher in transgenic plants than in nontransgenic plants. Our findings revealed that the GbF3′5′H1 gene functions in the biosynthesis of flavonoid-related metabolites, suggesting that GbF3′5′H1 represents a prime candidate for future studies (e.g., gene-editing) aiming to optimize ginkgo flavonoid production, especially that of flavan-3-ols. Full article
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Open AccessArticle
Phytochemical Evaluation of Tinctures and Essential Oil Obtained from Satureja montana Herb
Molecules 2020, 25(20), 4763; https://doi.org/10.3390/molecules25204763 - 16 Oct 2020
Abstract
Winter Savory (Satureja montana L.) has been used in traditional medicine and as a spice or natural food preservative in the Mediterranean region for centuries. In this paper, some technological and analytical aspects of the S. montana tinctures development and an evaluation [...] Read more.
Winter Savory (Satureja montana L.) has been used in traditional medicine and as a spice or natural food preservative in the Mediterranean region for centuries. In this paper, some technological and analytical aspects of the S. montana tinctures development and an evaluation of the essential oil composition are provided. The total phenolic and flavonoid contents and phenolic compounds profile analyzed spectrophotometrically and by high-performance thin-layer chromatography (HPTLC), respectively, were evaluated in the developed tinctures. The results showed that the tinctures prepared from the S. montana herb by maceration or remaceration are rich in polyphenols, and there is an influence of the technological factors (particle size and extraction mode) on the total phenolic and flavonoid contents. Caffeic, rosmarinic, and chlorogenic acids, (–)-catechin and rutin were identified in the tinctures using the HPTLC method. p-Thymol (81.79%) revealed by gas chromatography-mass spectrometry (GC-MS) was the predominant compound of the essential oil of this plant. Thus, the high contents of polyphenols and flavonoids in the developed tinctures and p-thymol among the volatile components of the S. montana essential oil could indicate the promising antioxidant and antimicrobial properties of these herbal preparations. The obtained results are a ground for the organization of the manufacture of the S. montana tincture and essential oil with the purpose of performing preclinical studies. Full article
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Open AccessArticle
A Comparison of Solubility, Stability, and Bioavailability between Astilbin and Neoastilbin Isolated from Smilax glabra Rhizoma
Molecules 2020, 25(20), 4728; https://doi.org/10.3390/molecules25204728 - 15 Oct 2020
Abstract
Astilbin and neoastilbin are two flavonoid stereoisomers. In the present study, their solubility, stability, and bioavailability were compared in a rat. The results revealed that the water solubility of astilbin and neoastilbin was 132.72 μg/mL and 217.16 μg/mL, respectively. The oil–water distribution coefficient [...] Read more.
Astilbin and neoastilbin are two flavonoid stereoisomers. In the present study, their solubility, stability, and bioavailability were compared in a rat. The results revealed that the water solubility of astilbin and neoastilbin was 132.72 μg/mL and 217.16 μg/mL, respectively. The oil–water distribution coefficient (log P) of astilbin and neoastilbin in simulated gastric fluid (SGF) was 1.57 and 1.39, and in simulated intestinal fluid (SIF) was 1.09 and 0.98, respectively. In SIF, about 78.6% astilbin remained after 4 h of incubation at 37 °C, while this value was 88.3% for neoastilbin. Most of the degraded astilbin and neoastilbin were isomerized into their cis-trans-isomer, namely neoisoastilbin and isoastilbin, respectively, and the decomposed parts were rare. For bioavailability comparison in a rat, an HPLC method for trace amounts of astilbin and neoastilbin determination in plasma was developed, and the pretreatment of plasma was optimized. A pharmacokinetic study showed that the absolute bioavailability of astilbin and neoastilbin in a rat showed no significant difference with values of 0.30% and 0.28%, respectively. Full article
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Open AccessArticle
The Antiproliferative Effects of Flavonoid MAO Inhibitors on Prostate Cancer Cells
Molecules 2020, 25(9), 2257; https://doi.org/10.3390/molecules25092257 - 11 May 2020
Abstract
Prostate cancer (PCa) patients commonly experience clinical depression. Recent reports indicated that monoamine oxidase-A (MAO-A) levels elevate in PCa, and antidepressant MAO-Is show anti-PCa properties. In this work, we aimed to find potential drugs for PCa patients suffering from depression by establishing novel [...] Read more.
Prostate cancer (PCa) patients commonly experience clinical depression. Recent reports indicated that monoamine oxidase-A (MAO-A) levels elevate in PCa, and antidepressant MAO-Is show anti-PCa properties. In this work, we aimed to find potential drugs for PCa patients suffering from depression by establishing novel anti-PCa reversible monoamine oxidase-A inhibitors (MAO-AIs/RIMA); with an endeavor to understand their mechanism of action. In this investigation, twenty synthesized flavonoid derivatives, defined as KKR compounds were screened for their inhibitory potentials against human MAO-A and MAO-B isozymes. Meanwhile, the cytotoxic and antiproliferative effects were determined in three human PCa cell lines. MAO-A-kinetics, molecular docking, SAR, cell morphology, and cell migration were investigated for the most potent compounds. The screened KKRs inhibited MAO-A more potently than MAO-B, and non-toxically inhibited LNCaP cell proliferation more than the DU145 and PC3 cell lines, respectively. The results showed that the three top MAO-AI KKRs compounds (KKR11, KKR20, and KKR7 (IC50s 0.02–16 μM) overlapped with the top six antiproliferative KKRs against LNCaP (IC50s ~9.4 μM). While KKR21 (MAO-AI) and KKR2A (MAO-I) were ineffective against the PCa cells. Furthermore, KKR21 and KKR11 inhibited MAO-A competitively (Kis ≤ 7.4 nM). Molecular docking of the two compounds predicted shared hydrophobic and distinctive hydrophilic interactions—between the KKR molecule and MAO-A amino acid residues—to be responsible for their reversibility. The combined results and SAR observations indicated that the presence of specific active groups—such as chlorine and hydroxyl groups—are essential in certain MAO-AIs with anti-PCa effects. Additionally, MAO-A inhibition was found to be associated more with anti-PCa property than MAO-B. Distinctively, KKR11 [(E)-3-(3,4-dichlorophenyl)-1-(2-hydroxy-4,6-dimethoxyphenyl)prop-2-en-1-one] exhibited anti-metastatic effects on the DU145 cell line. The chlorine substitution groups might play vital roles in the KKR11 multiple actions. The obtained results indicated that the flavonoid derivative KKR11 could present a novel candidate for PCa patients with depression, through safe non-selective potent inhibition of MAOs. Full article
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