Phenolic compounds from Trigonostemon honbaensis and their cytotoxic activity

Seven phenolic compounds including (±)‐erythro‐1‐(3′,4′,5′‐trimethoxyphenyl)propane‐1,2‐diol (1), (±)‐threo‐1‐(3′,4′,5′‐trimethoxyphenyl)propane‐1,2‐diol (2), (R)‐3‐3‐(3′,4′‐dimethoxyphenyl)propane‐1,2‐diol (3), (±)‐3‐(3′,4′,5′‐trimethoxyphenyl)propane‐1,2‐diol (4), (+)‐syringaresinol (5), (7S,8R,8′R)‐5,5′‐dimethoxylariciresinol (6), juniperoside (7) were isolated from the leaves of Trigonostemon honbaensis. Their chemical structures were determined using ESI‐MS, 1D NMR, and 2D NMR spectra and in comparison with the reported literature. Compounds1‐ 7 were reported from Trigonostemongenus for the first time. At concentration of 30 μM, compounds 1‐7 exhibited weak cytotoxic activity with cell viability percentages as low as 73.3±0.87 % and 79.5±0.23 % on CAL‐27 and MDA‐MB231 cell lines, respectively.