New phenolic derivatives and bioactive constituents from Castanopsis lamontii Hance: enzyme inhibitory activities and structure-activity insights.
TL;DR
Phytochemical investigation of the mature leaves of Castanopsis lamontii led to the isolation of two new phenolic derivatives, lamontin B and 6-O-(5-O-methylgalloyl)-D-glucopyranose and eleven known compounds that were elucidated through extensive spectroscopic analysis.
Abstract
Phytochemical investigation of the mature leaves of Castanopsis lamontii, an underexplored traditional folk medicine, led to the isolation of two new phenolic derivatives, lamontin B (1) and 6-O-(5-O-methylgalloyl)-D-glucopyranose (2) and eleven known compounds. Their structures were elucidated through extensive spectroscopic analysis. Bioactivity assays revealed that kaempferol (10), quercetin (11), and castanopsinin E (13) exhibited potent α-glucosidase inhibitory activities (IC50: 0.03-0.15 mM), which were significantly more active than the positive control acarbose (IC50: 1.5 mM). Furthermore, isodehydrodigallic acid (4), 10, and 11 displayed significant tyrosinase inhibition (IC50: 0.32-0.61 mM), surpassing kojic acid (IC50: 0.83 mM). Structure-activity relationship analysis suggested that the C-28 glycosylation in triterpenoid ellagitannins and the B-ring catechol moiety in flavonoids are pivotal for their α-glucosidase inhibition.