Baoliang CuiHeebyung ChaiHoward L. ConstantThawatchai SantisukVichai ReutrakulChristopher W.W. BeecherNorman R. FarnsworthGeoffrey A. CordellJohn M. PezzutoA. Douglas KinghornUniversity of Illinois at ChicagoThe Forest Herbarium, Thailand Ministry of Natural Resources and EnvironmentMahidol University2018-07-042018-07-041998-04-01Phytochemistry. Vol.47, No.7 (1998), 1283-1287003194222-s2.0-0032051786https://repository.li.mahidol.ac.th/handle/20.500.14594/18254Activity-directed fractionation of a stem extract of Azadirachta excelsa using KB (human oral epidermoid carcinoma) cells led to the isolation of four meliacin-type limonoids. Two of these constituents were novel, namely, 2,3- dihydronimbolide and 3-deoxymethylnimbidate, and these were purified along with the known compounds, nimbolide and 28-deoxonimbolide. The structures of the new compounds were determined by spectroscopic methods. Nimbolide and 28- deoxonimbolide were broadly cytotoxic when evaluated against a panel of human cancer cell lines, while the two novel compounds were inactive in this regard. The defection of nimbolide and 28-deoxonimbolide as cytotoxic constituents was facilitated by an electrospray LC/MS dereplication procedure.Mahidol UniversityAgricultural and Biological SciencesBiochemistry, Genetics and Molecular BiologyArticleSCOPUS10.1016/S0031-9422(97)00711-5