Baphicacanthcusines A-E, Bisindole Alkaloids from the Leaves of Baphicacanthus cusia (Nees) Bremek.

Four pairs of stereoisomeric indole alkaloids, (±)-baphicacanthcusines A-D (1-4), and one new indole alkaloid, baphicacanthcusine E (5), together with nine known compounds were identified from the leaves of Baphicacanthus cusia. (±)-1 and -2 possess an unprecedented skeleton in which two indole moieties are bridged by a phenylpropane unit. (±)-3 represents the first natural dispiro-oxazolidinone bisoxindoles. The absolute configurations in 1-5 were assigned based on quantum chemical calculations, including the calculated chemical shift with DP4plus analysis, the calculated optical rotation values, and the calculated electronic circular dichroism spectra. A plausible biosynthetic pathway for 1-5 was proposed. Compounds (±)-1, (-)-2, and 11 exhibited cytotoxicity against MCF-7 cells with IC50 values of 20.0-78.5 µM.

New alkylresorcinols from the fruits of Embelia ribes.

Nine new alkylresorcinols, designated as embelialkylresorcinols A-I (1-9), along with five known compounds (10-14) were isolated from the fruits of Embelia ribes. Their structures were elucidated by extensive spectroscopic analysis (1D, 2D NMR and HRESIMS), optical rotation data and modified Mosher method. Notably, embelialkylresorcinols A-H (1-8), possessing double aromatic rings linked with an aliphatic chain, are reported from the genus of Embelia (Myrsinaceae) for the first time. Most of the isolated compounds were evaluated for cytotoxic activity, and the results indicated that compounds 3, 5, 6 and 8 displayed moderate cytotoxicity against three human cancer cell lines (Hep3B, A549 and HCC1806) with IC50 values ranging from 23.06 to 41.49 µM.