Studies On Chemical Constituents Of Leaves And Stems Of Taxus Yunnanensis & Semisynthesis And Structure Activity Relationship Of Taxol Analogs

Taxol, a complex diterpene first isolated from the bark of Taxus brevifolia, is currently considered one of the most important anti-cancer agents. The bark from several species of Taxus, very slow-growing evergreens, currently supplies taxol. However, cutting the bark is obviously fatal to the source. In order not to threaten the plant source in the obtainment of taxol and related bioactive taxoids, investigation on the leaves and stems of Taxus yunnanensis indigenous to China has been performed.32 compounds were obtained from the leaves and stems of T. yunnanensis by CC, VLC, PTLC, MPLC, and HPLC chromatographic methods. 25 of them werededuced as taxoids by FAB-MS, UV, IR, ¹H, ¹³C-NMR, ¹H-¹³C COSY, ¹H-¹H COSY, HMBC and NOE spectra and X-ray crystallography. They include threeskeleton types of taxanes (6/10/6, 6/8/6, 5/7/6), and assignable to 8 subtypes. Six of them are new compounds and named taxin B(5), 2-deacetyl taxin B(8), taxayuntin E, F and G(14, 10, 18), 5-decinnamoyl-11,12-dihydro-11,12-epoxy-taxinine B(21), respectively. The rest were known taxoids including taxol, cephalomannine, 10-deacetyl-7-epi-taxol, 10-deacetyl-7-epi-cephalomannine, baccatin III, 10-deacetyl baccatin III, 19-hydroxy baccatin III, taxagifine, 1-hydroxy baccatin I, 1-hydroxy-5-deacetyl baccatin I, 2-deacetoxy taxinine J, 5-decinnamoyl taxinine J, baccatin VI,...