title: New tirucallane-type triterpenes from Dysoxylum variabile.
abstract: Eight new tirucallane-type triterpenes, dyvariabilins A-H (1-8), three known tirucallanes, niloticin (9), dihydroniloticin (10), and tirucalla-7,24-diene-3 beta,23-diol (11), and two known sesquiterpenes, 1-(1-hydroxy-2-methylpropyl)-3a-methyl-7-methyleneoctahydroinden-4-ol and (+)-aphanamol I, were isolated from the stem bark of Dysoxylum variabile. Tirucallanes 1 and 11 with an allylic hydroxy group in the side chain and dyvariabilin C (3) with an alpha-epoxy group at positions 7 and 8 showed high instability in acidic medium and formed five hitherto unknown semisynthetic tirucallanes. Dyvariabilins B (2) and C (3) as well as the mixtures of dyvariabilins E and F (5 and 6) and dyvariabilins G and H (7 and 8) showed weak cytotoxicity against KB cells.
authors: Department of Applied BioSciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, CH-8057 Zürich, Switzerland.
authors: H
authors: H
authors: Liu
authors: J
authors: J
authors: Heilmann
authors: T
authors: T
authors: Rali
authors: O
authors: O
authors: Sticher
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D008956:Models, Chemical; D010936:Plant Extracts / Q000302:isolation & purification* / Q000494:pharmacology; D014197:Trees / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D010936:Plant Extracts; D014315:Triterpenes