Excelxylin A: a new seco A-ring tirucallane triterpenoid from the stem bark of Dysoxylum excelsum .

A new seco -A tirucallane triterpenoid named excelxylin A ( 1 ), along with two known seco -A triterpenoids ( 2-3 ), were isolated from the n -hexane extract of Dysoxylum excelsum (Spreng.) Blume ex G.Don stem bark. The structure and stereochemistry configuration of compounds 1-3 was established by NMR, IR, and HR-ESI-MS spectroscopic data analyses and comparison of their NMR data with literatures. The compounds exhibited the carbon framework for seco -A ring tirucallane triterpenoid, first reported in the Dysoxylum genus. All compounds were tested for their cytotoxicity against human cervical HeLa cells.