Benzofuran glycosides and coumarins from the bark of Streblus indicus (Bur.) Corner. (June 2017) - He, Ruijie
Abstract: Two pairs of rare benzofuran glucoside epimers, indicuses A and B and indicuses C and D, three biogenetically related compounds indicuses E–G, and one coumarin indicus H, as well as 11 known compounds, were isolated from the bark of Streblus indicus (Bur.) Corner. The structures of indicuses A–H were elucidated by NMR and MS data, as well as by CD. ( S )-Marmesinin exhibited moderate antimicrobial activity in vitro against Bacillus subtilis and Saccharomyces cerevisiae . 7, 8-Dihydroxy-3-(3-methyl-2-butenyl) coumarin, umbelliferone, and scopoletin displayed strong cytotoxic activity in vitro against human bladder carcinoma cell line EJ. The structure-activity relationships indicate that hydroxylation at C-7 in the cytotoxic compounds is crucial to their activities. Graphical abstract: Seven benzofuran glycosides and a coumarin, together with 11 known compounds, were isolated from the bark of Streblus indicus (Bur.) Corner. Their structures were elucidated by NMR and MS, as well as by use of quantum chemical CD calculations. Highlights: 8 benzofuran glycosides and coumarins, and 11 known ones, were isolated from bark of Streblus indicus (Bur.) Corner. Two pairs of epimers were isolated by chiral HPLC. Absolute configurations were elucidated by spectroscopic data and quantum chemical CD calculations. Three coumarins displayed cytotoxic activity against human bladder carcinoma cell line EJ.