24-Epimarkhacanasin C, An Epimeric Cycloartane-Type Triterpenoid from the Leaves of Markhamia stipulata var. canaense

One new cycloartane-type triterpenoid, named 24-epimarkhacanasin C ( 1 ), together with four known flavonoids, apigenin ( 2 ), luteolin ( 3 ), apigenin 7-O- β -D-glucopyranoside ( 4 ), and luteolin 7-O- β -Dglucopyranoside ( 5 ), was isolated by various chromatographic methods from the ethyl acetate extract of Markhamia stipulata var. canaense leaves. Their structures were elucidated by IR, UV, HR-ESI-MS, and NMR experiments. All compounds were reported for the first time from this species. Their cytotoxicities were evaluated against human breast cancer cell line (MCF-7) by SRB assay. The isolated compounds 1 , 3 , and 4 exhibited significant cytotoxic activity (IC 50 ranged from 53.38 to 68.32 μg/mL), while compounds 2 and 5 did not show activity.