Flavones from Combretum Quadarangulare Growing in Vietnam and Their Alpha-Glucosidase Inhibitory Activity

PhD.Nguyen Huu HungThi-Bich-Ngoc Dao, Truong-Minh-Tri Nguyen, Van-Quy Nguyen, Thi-Minh-Dinh Tran, Nguyen-Minh-An Tran, Chuong Hoang Nguyen, Thi-Hoai-Thu Nguyen, Jirapast Sichaem, Cong-Luan Tran, Thuc-Huy Duong

Faculty of Technology

Research output: Article

researchs.abstract

Combretum quadrangulare Kurz is widely used in folk medicine in Eastern Asia and is associated with various ethnopharmacological properties including hepatoprotective, antipyretic, analgesic, antidysenteric, and anthelmintic activities. Previous phytochemical investigations reported the presence of numerous triterpenes (mostly cycloartanes, ursanes, lupanes, and oleananes) along with dozens of flavonoids. However, the extracts of C. quadrangulare and isolated flavonoids have not been evaluated for their alpha-glucosidase inhibition. In the frame of our efforts dedicated to the chemical investigation of Vietnamese medicinal plants and their biological activities, a phytochemical study of the MeOH extract of the leaves of C. quadrangulare using bioactive guided isolation was undertaken. In this paper, the isolation and structure elucidation of twelve known compounds, 5-hydroxy-3,7,4′-trimethoxyflavone (1), ayanin (2), kumatakenin (3), rhamnocitrin (4), ombuin (5), myricetin-3,7,3′,5′-tetramethyl ether (6), gardenin D (7), luteolin (12), apigenin (13), mearnsetin (14), isoorientin (15), and vitexin (16) were reported. Bromination was applied to compounds 2 and 3 to provide four new synthetic analogues 8–11. All isolated and synthesized compounds were evaluated for alpha-glucosidase inhibition and antibacterial activity. Compounds 4 and 5 showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus while others were inactive. All compounds failed to reveal any activity toward extended spectrum beta-lactamase-producing Escherichia coli. Compounds 2, 4, 6–9, and 11–14 showed good alpha-glucosidase inhibition with IC50 values in the range of 30.5–282.0 µM. The kinetic of enzyme inhibition showed that 8 and 11 were noncompetitive type inhibition against alpha-glucosidase. In silico molecular docking model indicated that compounds 8 and 11 were potential inhibitors against enzyme α-glucosidase.

Overview
Type
Article
Publication year
26 Apr 2021
Original language
English
Published Journal
Molecules
Volume No
Vol. 26 Issue 9
Classification
ISI/Scopus Indexed
ISSN index
1420-3049
Page
2531
Quartiles
Q2

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