A system for the production of [14C]taxol in vitro has been devised. The aseptic system utilized an appropriate 14C-labeled precursor, a reducing environment (dithiothreitol) and aseptically prepared pieces of the inner bark of Taxus brevifolia (Pacific yew). [14C]Phenylalanine and [14C]leucine are the best precursors, of the compounds tested, for [14C]taxol production. However, in the standard assay sodium [1-14C]acetate is used because of its relatively low price and its ability to label taxol uniformly. Chlorocholine chloride, an inhibitor of plant steroid metabolism, was an effective stimulator of [14C]taxol production, as were certain fungal elicitors. Taxol biosynthetic activity is greatest in the bark from lower portions of the main stem (trunk: 1 m from ground level).
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The authors wish to acknowledge the help of Dr. J. Sears, MSU Chemistry Dept,, for his assistance in acquiring mass spectral data on taxol samples. Also the assistance of Dr. D. Stierle and Suzan Strobel is acknowledged in helping us to acquire yew samples. Suzan Strobel kindly prepared the drawing of Pacific yew. Assistance from the American Cancer Society, the National Cancer Institute, the National Science Foundation, the U.S. Forest Service, the Montana Science and Technology Alliance and the Montana Agric. Experiment Station is also appreciated.
- Pacific yew