Isolation and Structures of Schleicherastatins 1−7 and Schleicheols 1 and 2 from the Teak Forest Medicinal Tree Schleichera oleosa

Bioassay (P-388 lymphocytic leukemia cell line)-guided separation of an extract prepared from the bark and stem of the Sri Lankan tree Schleichera oleosa led to the isolation of seven cancer cell growth inhibitory hydroxylated sterols designated schleicherastatins 1−7 (1−7) and two related sterols, schleicheols 1 and 2 (8, 9). The structure of schleicherastatin 1 (1) was completely elucidated by X-ray crystal structure determination. Based upon that defined structure, the remaining new sterol structures were deduced by highfield (300 and 500 MHz) NMR and MS interpretations. In this new series of sterols, hydroxylation at C-22 appears to be important for promoting cancer cell growth inhibition.