Chemical constituents from the pericarp of Trewia nudiflora

Three new ent-atisane diterpenes, i.e., 17-hydroxy-ent-atisan-19-oic acid (1), 17-hydroxy-ent-atisan-19-oic acid methyl ester (2), and 16alpha,17-dihydroxy-ent-atisan-19-al (3), together with five known phenolic compounds, Le., gallic acid, ethyl gallate, protocatechuic acid, 3,4,4'-tri-O-methylellagic acid, and a-tocopherol, and two other known compounds, i.e., trans-cinnamic acid and taraxerone, were isolated from the pericarp of Trewia nudiflora collected in Xishuangbanna, Yunnan Province, China. Their structures were elucidated by spectroscopic analysis including 1D- and 2D-NMR. Trace amounts of maytansinoids were isolated by antifungal-activity-guided fractionation and determined by LC-ESI-MS analysis; they were prominent antifungal constituents in the pericarp of Trewia nudiflora.