Antitumor activities of extracts and compounds from water decoctions of Taxus cuspidata.

Water decoctions from the leaves of Taxus cuspidata are used in traditional Chinese medicine to treat cancer, suggesting that water soluble constituents from these leaves may possess anticancer properties. Interestingly, hydrophilic paclitaxel derivatives, as opposed to paclitaxel itself, can be detected by high pressure liquid chromatography in water decoctions from these leaves. The remainder extracts, which are free of paclitaxel and hydrophilic paclitaxel derivatives, from the T. cuspidata leaves were investigated for antitumor activity in vivo and in vitro for the first time in this study. EE80B, 7-xylosyl-10-deacetylpaclitaxel and 7-xylosyl-10-deacetylpaclitaxel C displayed the most antitumor activity in vivo. However, in vitro studies with tumor cell lines showed that EE80B had a significantly smaller antitumor effect than paclitaxel. We hypothesize that water decoctions from T. cuspidata leaves exhibit antitumor effects in vivo, which may be aided by the activation of specific host mechanisms (e.g. stimulation of antitumor immunity) which are not present in vitro.