Flavones and cytotoxic constituents from the stem bark of Muntingia calabura

Two new flavones, 8-hydroxy-7,3',4',5'-tetramethoxyflavone and 8,4'-dihydroxy-7,3',5'-trimethoxyflavone, together with thirteen known compounds have been isolated from the stem bark of Muntingia calabura. The structures of two new compounds were determined through spectral analyses. Among the isolates, 8-hydroxy-7,3',4',5'-tetramethoxyflavone, 8,4'-dihydroxy-7,3',5'-trimethoxyflavone, and 3-hydroxy-1-(3,5-dimethoxy-4-hydroxyphenyl)propan-1-one exhibited effective cytotoxicities (ED50 values = 3.56, 3.71, and 3.27 mug/mL, respectively) against the P-388 cell line in vitro.