Sonja SturmRoberto R. GilHee Byung ChaiOlipa D. NgassapaThawatchai SantisukVichai ReutrakulAnne HoweMarcia MossJeffrey M. BestermanShi Lin YangJohn E. FarthingR. Murray TaitJane A. LewisMelanie J. O'NeillNorman R. FarnsworthGeoffrey A. CordellJohn M. PezzutoA. Douglas KinghornUniversity of Illinois at ChicagoThe Forest Herbarium, Thailand Ministry of Natural Resources and EnvironmentMahidol UniversityGlaxoSmithKline, USAGlaxoSmithKline2018-07-042018-07-041996-07-01Journal of Natural Products. Vol.59, No.7 (1996), 658-663016338642-s2.0-9444255826https://repository.li.mahidol.ac.th/handle/20.500.14594/17540Chloroform-soluble extracts of the stems and of the mixed stems and stem bark of Lophopetalum wallichii were found to be inhibitory in a farnesyl protein transferase (FPTase) bioassay system. During the course of activity- guided fractionation, the known lupane-type triterpenes, ochraceolide A (1), ochraceolide B (2), betulin, and lupeol and the new lupane lactone, dihydro ochraceolide A (4), were isolated. The stereochemistry of the epoxide group of ochraceolide B (2) was determined by preparation of both epoxide isomers [2, and the new semisynthetic derivative, 20-epi-ochraceolide B (3)] from 1. The structure of 4 was established by reduction of 1 with sodium borohydride. Compounds 1 and 2 exhibited significant inhibitory activity in the FPTase assay (IC50values of 1.0 and 0.7 μg/mL, respectively). Lupeol was found to be weakly active (IC5065.0 μg/mL) in this test system, whereas no significant inhibition was detected for betulin or compounds 3 or 4. When evaluated against a panel of human cancer cells in culture, compounds 1 and 4 were modestly cytotoxic. Compounds 2 and 3 were not active in the panel.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyChemistryMedicinePharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1021/np960370u