Factors influencing the in vitro production of radiolabeled taxol by Pacific yew, Taxus brevifolia

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).