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Molecules
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Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II
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Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II

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

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 11478

Special Issue Editor

Dr. Nawaf Al-Maharik

E-Mail 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 Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Flavonoids, a class of secondary metabolites, reperenst a large and various groups of substances that have a C6-C3-C6 carbon framework. Flavonoinds are abundantly present in the majority of fruits, vegatables, grains, and herbs. The high accessibility of flavonoids combined with their low toxicity and high specificty in comparison to others plant constituents allows them to be consumed in larger quantities by animals and humans. They are now considered to be a vital 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, as well as their synthesis, isolation, characterization, and possible applications as a result of their health benefits, has received additional attention along with the finding of their association with the prevention of various diseases, as well as the extrapolation of flavonoids to be used as potential drugs for preventing chronic diseases.

The objective in assembling this Special Issue on flavonoids an their isolation, identification, characterization, and synthesis is to provide scientists from different disciplines insight into the scope and complexity of this multidimensional field.

There is no limitation regarding the topics, as long as they fall into the course of flavonoid chemistry. Original and review articles on the below topics or on other topics related to the chemistry of flavonoids are welcome.

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 submissions that pass pre-check are 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 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

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

Related Special Issue

Published Papers (5 papers)

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Research

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12 pages, 2423 KiB  
Article
Synthetic Studies toward 5,6,7,3′,4′-Monomethoxytetrahydroxyflavones: Synthesis of Pedalitin
by Koteswara Rao Kamma, Joungmo Cho, Hyo Jun Won, So-Yeon Nam, Ngan Hong Le, Je Hyeong Jung and Kee-In Lee
Molecules 2024, 29(2), 513; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29020513 - 19 Jan 2024
Viewed by 639
Abstract
During the synthetic studies toward 5,6,7,3′,4′-monomethoxytetrahydroxyflavones, a concise pedalitin synthesis procedure was achieved. As previously reported, 6-hydroxy-2,3,4-trimethoxyacetophenone was prepared by Friedel–Crafts acylation of 1,4-dihydroxy-2,6-dimethoxybenzene with boron trifluoride diethyl etherate in acetic acid. When aldol condensation of 6-hydroxy-2,3,4-trimethoxyacetophenone 2b with vanillin was performed in [...] Read more.
During the synthetic studies toward 5,6,7,3′,4′-monomethoxytetrahydroxyflavones, a concise pedalitin synthesis procedure was achieved. As previously reported, 6-hydroxy-2,3,4-trimethoxyacetophenone was prepared by Friedel–Crafts acylation of 1,4-dihydroxy-2,6-dimethoxybenzene with boron trifluoride diethyl etherate in acetic acid. When aldol condensation of 6-hydroxy-2,3,4-trimethoxyacetophenone 2b with vanillin was performed in basic conditions, it produced 2′-hydroxychalcone 3b, and, surprisingly, along with 3-hydroxyflavone 4 in a considerable amount. We propose that this oxidative cyclization is presumably due to the contribution of a quinone methide, likely to be subjected to aerobic oxidation. The chalcone was then subjected to oxidative cyclization with iodine in dimethyl sulfoxide to afford flavone 5 in good yield. To our delight, serial demethylation of the three methoxy groups at the 5-, 6-, and 3′-positions of 5 proceeded smoothly to produce pedalitin 1, under hydrogen bromide solution (30% in acetic acid). The crystal structures of 3-hydroxyflavone 4 and pedalitin tetraacetate 6 were unambiguously determined by X-ray crystallography. Full article
(This article belongs to the Special Issue Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II)
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18 pages, 3248 KiB  
Article
Preparation, Characterization and Evaluation of Flavonolignan Silymarin Effervescent Floating Matrix Tablets for Enhanced Oral Bioavailability
by Sher Ahmad, Jamshaid Ali Khan, Tabassum Naheed Kausar, Mater H. Mahnashi, Ali Alasiri, Abdulsalam A. Alqahtani, Thamer S. Alqahtani, Ismail A. Walbi, Osama M. Alshehri, Osman A. Elnoubi, Fawad Mahmood and Abdul Sadiq
Molecules 2023, 28(6), 2606; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28062606 - 13 Mar 2023
Cited by 3 | Viewed by 1777
Abstract
The convenient and highly compliant route for the delivery of active pharmaceutical ingredients is the tablet. A versatile platform of tablets is available for the delivery of therapeutic agents to the gastrointestinal tract. This study aimed to prepare gastro retentive drug delivery floating [...] Read more.
The convenient and highly compliant route for the delivery of active pharmaceutical ingredients is the tablet. A versatile platform of tablets is available for the delivery of therapeutic agents to the gastrointestinal tract. This study aimed to prepare gastro retentive drug delivery floating tablets of silymarin to improve its oral bioavailability and solubility. Hydroxypropyl methylcellulose (HPMCK4M and HPMCK15), Carbopol 934p and sodium bicarbonate were used as a matrix, floating enhancer and gas generating agent, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, in vitro drug release, in vivo floating behavior and in vivo pharmacokinetics. The drug–polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infrared (FTIR). The floating lag time of the formulation was within the prescribed limit (<2 min). The formulation showed good matrix integrity and retarded the release of drug for >12 h. The dissolution can be described by zero-order kinetics (r2 = 0.979), with anomalous diffusion as the release mechanism (n = 0.65). An in vivo pharmacokinetic study showed that Cmax and AUC were increased by up to two times in comparison with the conventional dosage form. An in vivo imaging study showed that the tablet was present in the stomach for 12 h. It can be concluded from this study that the combined matrix system containing hydrophobic and hydrophilic polymers min imized the burst release of the drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only a hydrophilic matrix. An in vivo pharmacokinetic study elaborated that the bioavailability and solubility of silymarin were improved with an increased mean residence time. Full article
(This article belongs to the Special Issue Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II)
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19 pages, 3294 KiB  
Article
Isolation, Identification and Pharmacological Effects of Mandragora autumnalis Fruit Flavonoids Fraction
by Nawaf Al-Maharik, Nidal Jaradat, Najlaa Bassalat, Mohammed Hawash and Hilal Zaid
Molecules 2022, 27(3), 1046; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27031046 - 03 Feb 2022
Cited by 10 | Viewed by 3393
Abstract
Since ancient times, Mandragora autumnalis has been used as a traditional medicinal plant for the treatment of numerous ailments. In light of this, the current study was designed to isolate and identify the chemical constituents of the flavonoids fraction from M. autumnalis ripe [...] Read more.
Since ancient times, Mandragora autumnalis has been used as a traditional medicinal plant for the treatment of numerous ailments. In light of this, the current study was designed to isolate and identify the chemical constituents of the flavonoids fraction from M. autumnalis ripe fruit (FFM), and evaluate its DPPH scavenging, anti-lipase, cytotoxicity, antimicrobial and antidiabetic effects. An ethyl acetate extract of M. autumnalis was subjected to a sequence of silica gel column chromatography using different eluents with various polarities. The chemical structures of the isolated compounds were identified using different spectral techniques, including 1H NMR and 13C NMR. FFM’s anti-diabetic activity was assessed using a glucose transporter-4 (GLUT4) translocation assay, as well as an inhibition against α-amylase and α-glucosidase using standard biochemical assays. The FFM anti-lipase effect against porcine pancreatic lipase was also evaluated. Moreover, FFM free radical scavenging activity using the DPPH test and antimicrobial properties against eight microbial strains using the micro-dilution method were also assessed. Four flavonoid aglycones were separated from FFM and their chemical structures were identified. The structures of the isolated compounds were established as kaempferol 1, luteolin 2, myricetin 3 and (+)-taxifolin 4, based on NMR spectroscopic analyses. The cytotoxicity test results showed high cell viability (at least 90%) for up to 1 mg/mL concentration of FFM, which is considered to be safe. A dose-dependent increase in GLUT4 translocation was significantly shown (p < 0.05) when the muscle cells were treated with FFM up to 0.5 mg/mL. Moreover, FFM revealed potent α-amylase, α-glucosidase, DPPH scavenging and porcine pancreatic lipase inhibitory activities compared with the positive controls, with IC50 values of 72.44 ± 0.89, 39.81 ± 0.74, 5.37 ± 0.41 and 39.81 ± 1.23 µg/mL, respectively. In addition, FFM inhibited the growth of all of the tested bacterial and fungal strains and showed the greatest antibacterial activity against the K. pneumoniae strain with a MIC value of 0.135 µg/mL. The four flavonoid molecules that constitute the FFM have been shown to have medicinal promise. Further in vivo testing and formulation design are needed to corroborate these findings, which are integral to the pharmaceutical and food supplement industries. Full article
(This article belongs to the Special Issue Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II)
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10 pages, 4785 KiB  
Article
New Flavone C-Glycosides from Scleranthus perennis and Their Anti-Collagenase Activity
by Katarzyna Jakimiuk, Jakub W. Strawa, Sebastian Granica and Michał Tomczyk
Molecules 2021, 26(18), 5631; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26185631 - 16 Sep 2021
Cited by 6 | Viewed by 2253
Abstract
Three new flavone glycosides, one known flavone glycoside, and the phenolic derivative apiopaenonside were isolated and identified from the ethyl acetate fraction of the aerial parts of Scleranthus perennis. The planar structures were elucidated through extensive analysis of UV-Vis, IR, and 1 [...] Read more.
Three new flavone glycosides, one known flavone glycoside, and the phenolic derivative apiopaenonside were isolated and identified from the ethyl acetate fraction of the aerial parts of Scleranthus perennis. The planar structures were elucidated through extensive analysis of UV-Vis, IR, and 1H NMR and 13C NMR spectral data, including the 2D techniques COSY, HSQC, and HMBC, as well as ESI mass spectrometry. The isolated compounds were established as 5,7,3′-trihydroxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (1), 5,7,3′-trihydroxy-4′-methoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (2), 5,7-dihydroxy-3′-methoxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (3), 5,7-dihydroxy-3′-methoxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-(4′′′-acetoxy)-glucoside (4), and apiopaenonside (5). Moreover, all isolated compounds were evaluated for anti-collagenase activity. All compounds exhibited moderate inhibitory activity with IC50 values ranging from 36.06 to 70.24 µM. Full article
(This article belongs to the Special Issue Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II)
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Review

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31 pages, 1723 KiB  
Review
Tectorigenin: A Review of Its Sources, Pharmacology, Toxicity, and Pharmacokinetics
by Juan Rong, Fei Fu, Chenxia Han, Yaling Wu, Qing Xia and Dan Du
Molecules 2023, 28(15), 5904; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28155904 - 05 Aug 2023
Cited by 4 | Viewed by 2362
Abstract
Tectorigenin is a well-known natural flavonoid aglycone and an active component that exists in numerous plants. Growing evidence suggests that tectorigenin has multiple pharmacological effects, such as anticancer, antidiabetic, hepatoprotective, anti-inflammatory, antioxidative, antimicrobial, cardioprotective, and neuroprotective. These pharmacological properties provide the basis for [...] Read more.
Tectorigenin is a well-known natural flavonoid aglycone and an active component that exists in numerous plants. Growing evidence suggests that tectorigenin has multiple pharmacological effects, such as anticancer, antidiabetic, hepatoprotective, anti-inflammatory, antioxidative, antimicrobial, cardioprotective, and neuroprotective. These pharmacological properties provide the basis for the treatment of many kinds of illnesses, including several types of cancer, diabetes, hepatic fibrosis, osteoarthritis, Alzheimer’s disease, etc. The purpose of this paper is to provide a comprehensive summary and review of the sources, extraction and synthesis, pharmacological effects, toxicity, pharmacokinetics, and delivery strategy aspects of tectorigenin. Tectorigenin may exert certain cytotoxicity, which is related to the administration time and concentration. Pharmacokinetic studies have demonstrated that the main metabolic pathways in rats for tectorigenin are glucuronidation, sulfation, demethylation and methoxylation, but that it exhibits poor bioavailability. From our perspective, further research on tectorigenin should cover: exploring the pharmacological targets and mechanisms of action; finding an appropriate concentration to balance pharmacological effects and toxicity; attempting diversified delivery strategies to improve the bioavailability; and structural modification to obtain tectorigenin derivatives with higher pharmacological activity. Full article
(This article belongs to the Special Issue Flavonoids: Their Isolation, Characterization, Synthesis and Health Benefits II)
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