Chemical Constituents From the Leaves of Grewia bulot Gagn. and Their Cytotoxic Activity

Objective: The ultimate objective of this study was to isolate bioactive compounds from Grewia bulot Gagn. leaves and evaluate their cytotoxicity against a panel of human cancer cell lines. Methods: Compounds were isolated by column chromatography, whereas their chemical structures were elucidated by NMR spectroscopic data, and literature comparison. The cytotoxic activity of the isolated compounds was assessed using SRB assay against 4 cancer cell lines, including MCF-7 (human breast carcinoma), Hep-G2 (human hepatocellular carcinoma), KB (human carcinoma in the mouth), and SK-LU-1 (human lung carcinoma). Results: From the n-hexane extract, 4 compounds were isolated and identified as taraxerol (1), 3-( E)-coumaroyltaraxerol (2), 3-( Z)-coumaroyltaraxerol (3), and lupeol (4). Additionally, 6 compounds were isolated from the ethyl acetate extract and identified as daucosterol (5), trans-tiliroside (6), inugalactolipid A (7), (3 S,5 R,6 S,7 E,9 R)-7-megastigmene-3,6,9-triol (8), biphenyl-3,3′,4,4′-tetrol (9), and smiglabrone B (10). Among these isolates, only compound 9 exhibited moderate cytotoxic activity against all tested cancer cell lines with the IC50 values ranging from 31.67 to 63.15 µM. Conclusion: All these compounds have been detected from G bulot for the first time, biphenyl-3,3′,4,4′-tetrol (9) emerged as a promising candidate for cancer drug development. This study contributes to the growing body of knowledge regarding natural compounds with anticancer properties.