New triterpene glycosides from the aerial parts of Myrsine semiserrata with cytotoxic and antimicrobial activities.

Two new triterpene glycosides, 3-O-α-l-arabinopyranosyl castanopsol (1) and 3-O-β-d-xylopyranosyl castanopsol (2) along with two known triterpene glycosides, eclalbasaponin II (3), spergulacin (4), and two known flavonoid glycosides, kaempferol 3-O-α-l-rhamnopyranoside (5), quercetin 3-O-α-l-rhamnopyranoside (6), were isolated from the aerial parts of Myrsine semiserrata Wall. Their structures were elucidated by extensive spectroscopic analysis (HR-ESI MS, 1D, and 2D NMR data) and by comparison with literature data for known compounds. Compounds 1-6 were evaluated for their cytotoxic activities against four cancer cell lines including KB, HepG2, A549, and MCF-7, as well as for their antimicrobial activity against a panel of clinically significant microorganisms. Compound 1 exhibited moderate cytotoxicity against KB, MCF-7, HepG2, and A549 cell lines, whereas 2 was much less active, exhibiting cytotoxicity only against A549 cells. In antimicrobial assays, 1 and 2 showed selective activity against Gram-positive bacteria, with 2 being more active (MIC = 32 μg/mL) than 1 (MIC = 64 - 128 μg/mL). These results suggest that variation in the sugar moiety may influence the biological activity of triterpene glycosides.