Sterols, triterpenes and biflavonoids of Viburnum jucundum and cytotoxic activity of ursolic acid.

The triterpenes ursolic acid (1), 27-p-Z-coumaroyloxyursolic acid (2), 27-p-E-coumaroyloxyursolic acid, alpha-amyrine-3-palmitate and lupeol-3-palmitate were isolated through a bioactivity-guided fractionation from the acetonic extract of the aerial parts of Viburnum jucundum Morton in addition to amentoflavone, an epimeric mixture at C-2 of 2,3-dihydroamentoflavone, beta-sitosterol and beta-sitosteryl glucopyranoside. Ursolic acid (1) was the only constituent that exhibited cytotoxic activity toward three human cancer cell lines in culture. This is the first phytochemical and cytotoxic analysis performed to this plant species.