A pair of new apotirucallane triterpenes, meliavolkensins A and B, from Melia volkensii (Meliaceae)

Two new bioactive apotirucallane triterpenes, meliavolkensins A (1) and B (2), were isolated from the root bark of Melia volkensii (Meliaceae). These two compounds have a new type of substituted tetrahydropyran ring side chain, and their structures have been elucidated by spectroscopic analyses. 1 and 2 also show cytotoxic selectivities to a hyman colon tumor cell line (H-29).