EFFECT OF WHITE-LIGHT ON TAXOL AND BACCATIN-III ACCUMULATION IN CELL-CULTURES OF TAXUS-CUSPIDATA SIEB AND ZUCC

Taxol is a diterpene amide derived from Taxus spp. and approved for th e treatment of ovarian and breast cancer in the USA. Taxus cuspidata c ell cultures represent an alternate source of taxol and related taxoid s. We have previously described the development, growth, and taxoid ac cumulation of cell cultures of T. cuspidata. The present study examine d the influence of white light on the accumulation of taxol and baccat in III callus and cell suspension cultures of T. cuspidata. Results sh owed that taxol and baccatin III accumulations were approximately thre e times higher in dark-grown calli. Dark-grown suspensions also displa yed three times more total volumetric taxol relative to light-grown su spensions; baccatin III amounts were similar in dark and light grown s uspensions. Growth of suspensions was two to three-fold higher in dark ness. Taxol accumulation peaked at stationary phase (d27 to d45) in da rk-grown cells (14mg . kg(-1)edw). The peak of baccatin III accumulati on (180 mg . kg(-1)edw) preceded the taxol peak (d18 to d27) and the c ontent of this taxoid decreased as taxol increased. Baccatin III accum ulation in the culture medium was similar in dark and light-grown susp ensions (peaked at 6.2 mg . L(-1) on d9). Taxol accumulation in the me dium was higher in darkness (0.3 mg . L(-1) on d9 and d27 to d36) than in light (0.08 mg . L(-1) on d9). Down-regulation of taxol steady-sta te amounts may be related to the effect of light on microsomal 3-hydro xy-3-methylglutaryl-coenzyme A reductase and mevalonate supply; the en zyme had significantly lower activity in light-grown cells.