Baccatin III is an isolate of the Pacific yew tree (Taxus brevifolia) and related species. Baccatin III is the precursor to paclitaxel/ taxol. Antileukaemic and antitumor agent, Baccatin III, binds to tubules when they are assembled in the cell and stabilizes the polymerized form of tubules so that they remain assembled even under conditions in which microtubules dissociate into tubulin subunits. Baccatin III is also an inducer of apoptosis and shows antitumor properties in vitro. Baccatin III exerts anti-tumor immunomodulatory activity in very low doses (0.05-0.5mg/kg), although it is regarded as an inactive derivative of paclitaxel. Oral administration of Baccatin III significantly reduced the growth of tumors induced by engrafting BALB/c mice with either 4 T1 mammary carcinoma or CT26 colon cancer cells. Baccatin III reduced tumor progression by inhibiting the accumulation and suppressive function of MDSCs. Baccatin III inhibited cell proliferation of a number of cancer cell lines. The cytotoxic activity exhibited by fungal taxol and Baccatin III involves the same mechanism, dependent on caspase-10 and membrane potential loss of mitochondria, with taxol having far greater cytotoxic potential.

10-deactyltaxol (10-deacetylpaclitaxel) is a naturally occurring taxane related to taxol (paclitaxel). Taxol is an antitumor drug with cytotoxic properties that correlate with its microtubule-stabilizing activities. When compared to paclitaxel 10-deacetyltaxol is 100% as active as paclitaxel in promoting in vitro microtubule assembly, but is only 30% as cytotoxic as paclitaxel. 10-deactyltaxol is a semi-synthetic precursor of paclitaxel and considered to be paclitaxel impurity. 10-deactyltaxol, isolated from the bark of Taxus brevifolia, was converted into paclitaxel in one composite step (trimethylsilylation, acetylation, and desilylation) and in an overall yield of 80-85%.