THIN-LAYER DRYING OF CULTIVATED TAXUS CLIPPINGS

A promising cancer chemotherapeutic agent, taxol, is currently schedul ed for full clinical development by the National Cancer Institute. The ornamental yew, Taxus x media 'Hicksii', has been identified as a ren ewable source of taxol. However, clippings from the plant must be prop erly and efficiently harvested, dried, and stored. Thin-layer drying s tudies of Taxus clippings, needles, and stems were conducted. Paramete rs for the thin-layer drying equation were successfully determined for drying temperatures of 30, 40, 50, and 60-degrees-C. The results show ed that drying rates increased 28-, 15-, and 3-fold as drying temperat ures increased from 30-degrees, 40-degrees, and 50-degrees-C to 60-deg rees-C, respectively. Also, stems dried at a faster rate than needles and needles dried at a faster rate than whole clippings. Taxol yields (g/100 g, db.) from stems were nearly constant for the four temperatur es tested. However, yields from needles increased linearly as drying t emperatures increased from 30 to 60-degrees-C. The highest taxol yield s were obtained from clippings. Nearly constant yields were obtained ( approximately 0.014 g/100 g, d.b.) for drying temperatures of 40, 50, and 60-degrees-C. The lowest yields for all three plant components occ urred when the drying temperature was set at 30-degrees-C. The results suggest 60-degrees-C is the best temperature set point for drying Tax us x media 'Hicksii', but temperatures higher than 60-degrees-C should be evaluated.