Abstract

So far huge studies have been reported on antioxidant effects of Camellia sinensis L. in animal/human cells, however little is known about its impacts in plant cells/tissue culture. In this investigation, we evaluated the biological effects of C. sinensis extract and cysteine on production of paclitaxel using tissue cultures of Taxus brevifolia L. Various calli and its subcultures were cultivated using B5 media in presence or absence of designated amount ofC. sinensis extract and cysteine. Activities of polyphenol oxidase (PPO) and peroxidase (PO), browning rate, callus growth and paclitaxel production were examined in the treated cultures of T. brevifolia. PPO and PO enzymes were found to be activated in the calli subcultures upon treatment with the C. sinensis extract. Subcultured callus of T. brevifoliatreated with cysteine (100 mg/L) showed lower activity of PPO, while those treated with high amounts of cysteine (>200 mg/L) displayed higher activities of these enzymes. Use of C. sinensis extract and cysteine failed to suppress the browning phenomenon, however tissues treated with these compounds showed significant increase in paclitaxel production (794 mg/kg dry weight of calli).  Based on our findings, the production of paclitaxel can be improved in subculture or suspension cell culture of T. brevifolia upon treatment with C. sinensis extract, which may be considered as a cost-beneficial elicitor.

Key words: Antioxidant, callus browning, tissue culture, cysteine, paclitaxe, polyphenol oxidase, proxidase, phenolics.