| Yew (Taxus sp) is recognized as a rare species of plant which is in danger of extinction in the world. Taxol, a broad-spectrum and high-activity anticancer product which has special anti-tumor mechanism, is derived from the needles, twigs, sprouts, even seeds, and relatively concentrate in bark of the Yew tree. Taxol is first found among taxane diterpene compounds having cytotoxic activity and a special effect on curing various kinds of cancer. Because of its unique characteristics, taxol become one of the most important anticancer agents derived from nature. However, the complicated isolating process, water-insolubility, and leanness in raw material limit the application of taxol in therapy of cancer. In southern China a subspecies of yew, Taxus mairei, is relatively abundant and widely planted. Its leaves contain relatively large amount of 10-deacetylbaccatin HI (10-DABIII), a precursor of synthesizing taxol.This work mainly studied the isolation and purification method of from leaves of Taxus mairei. Overall, 7.9% of 10-DABIII was obtained from leaves of Taxus mairei via pre-treating, extracting, chromatography separating, and recrystallization. This research shows that 1:5 (g:ml) petroleum ether extraction for 9-10 hours can remove about 30-40% of impurities in the extracting product. Almost all 10-DABIII in the pretreated leaves of Taxus mairei was extracted after triple 95% (v/v) methanol extraction for 12 hours. It was found that ethyl acetate is more effective in recovering 10-DABIII from methanol extraction than butyl acetate. Rinsed by 5% of NaHCO3 in 1:4 (v:v) proportions, the ethyl acetate extraction can be further purified. When 1:3 (v:v) of petroleum ether/ chloroform was used as desorption solution during the silicon-gel-adsorption chromatography separation, 10-DABIII in ethyl acetate extraction can be well separated from taxane diterpene compounds. After a seriese of recystallization in acetonitrile and methanol/water, the purity of 10-DABIII can reach 91%.
|
PDF Full Text Request