Phenylethanoid Glycosides From Clerodendrum bungei and Their Cytotoxic Activities

ABSTRACT One new phenylethanoid glycoside, named bungaside A ( 1 ), along with six known phenylethanoid glycosides ( 2 – 7 ), were isolated from the dried aerial parts of Clerodendrum bungei Steud. Their structures were elucidated from extensive spectroscopic analysis and hydrolysis. All the isolates were evaluated for their anti‐tumor effects against H460, A549, and HepG2 cancer cell lines. Compound 7 showed moderate activity against all cell lines, with the half‐maximal inhibitory concentration (IC 50 ) values ranging from 2.25 to 13.13 µM. Meanwhile, compounds 3 and 6 displayed weak activities on A549 with the IC 50 values of 11.61 ± 1.38 and 16.68 ± 1.16 µM. Compounds 3 and 6 displayed moderate activities on H460 with the IC 50 values of 5.10 ± 0.12 and 7.23 ± 0.65 µM, respectively. Besides, the preliminary structure‐activities relationship showed that the skeleton of phenylethanoid glycosides containing a monosaccharide may have a stronger anticancer effect than their corresponding disaccharides, and the increase in the methylation of the hydroxyl group on the aromatic ring is also an important reason decrease in activity.