Mangostanaxanthone VIIII, a new xanthone from Garcinia mangostana pericarps, α-amylase inhibitory activity, and molecular docking studies

ABSTRACT A new xanthone: mangostanaxanthone VIIII [1,3,5,6,7-pentahydroxy-2-(3-methylbut-2-enyl)-8-(3-hydroxy-3-methylbut-1-enyl) xanthone] (5) and four known xanthones: mangostanaxanthones I (1) and II (2), γ-mangostin (3), and mangostanaxanthone VII (4) were separated and characterized from the acetone fraction of Garcinia mangostana L., Clusiaceae (mangosteen) pericarps. Their structures were established based on various spectroscopic analyses in addition to HRMS and comparison with the literature. The α-amylase inhibitory potential of the isolated metabolites was evaluated. Compounds 1, 2, and 5 had the highest activity with % inhibition 72.5, 86.5, and 81.8, respectively compared to acarbose (97.1%, reference α-amylase inhibitor). The molecular docking study of the tested metabolites was estimated to shade up the rational explanation of the α-amylase inhibitory activity results. Moreover, the pharmacokinetic parameters were assessed using Swiss ADME. It is noteworthy that 1, 2, and 5 had similar binding poses as the X-ray crystal structure of acarbose, whereas the other metabolites possessed different binding mode that decreased their inhibitory capacity. Thus, these data reinforced the health benefit of mangosteen as an alternative medicine to help lowering the postprandial glucose absorption. Therefore, it could have a good potential for the treatment of diabetes.

Lipoxygenase inhibitors flavonoids from Cyperus rotundus aerial parts

ABSTRACT Cyperus rotundus L. (Suada, Sueda, family: Cyperaceae) is vastly spread in several world's subtropical and tropical regions. It had variable traditional uses and bioactivities. A new flavonol derivative: cyperaflavoside (myricetin 3,3',5'-trimethyl ether 7-O-β-D-glucopyranoside) and five flavonoids: vitexin, orientin, cinaroside, quercetin 3-O-β-D-glucopyranoside, and myrcetin 3-O-β-D-glucopyranoside were separated from the methanolic extract of C. rotundus aerial parts. Their structures were verified based on UV, IR, NMR (1D and 2D), HRESIMS, and comparison with literature. All metabolites were assessed for their 5-lipoxygenase inhibitory potential. All compounds possessed 5-lipoxygenase inhibitory potentials with IC50s 5.1, 4.5, 5.9, 4.0, 3.7, and 2.3 µM, respectively, in comparison to indomethacin (IC50 0.98 µM). These results supported the traditional uses of C. rotundus in treating inflammation and its related symptoms.