PRECURSOR BIOTRANSFORMATION IN IMMOBILIZED PLACENTAL TISSUES OF CAPSICUM FRUTESCENS MILL .1. INFLUENCE OF FEEDING INTERMEDIATE METABOLITES OF THE CAPSAICINOID PATHWAY ON CAPSAICIN AND DIHYDROCAPSAICIN ACCUMULATION

摘要

In order to enhance the levels of capsaicinoids in vitro and to optimise the suitable precursor, immobilized placental tissues of Capsicum frutescens were fed with intermediates of the capsaicinoid pathway. Feeding t-cinnamic acid, p-coumaric acid, caffeic acid or ferulic acid (2.5 mM final concentration) resulted in a greater accumulation of capsaicin and dihydrocapsaicin than was achieved with the distant precursors phenylalanine and l-valine. Of all the precursors, coumaric acid was found to be the best for capsaicin and dihydrocapsaicin formation, resulting in an accumulation. of 2890.8 mu g/culture and 818 mu g/culture, respectively, in 5 days of culture. Maximum conversion to capsaicin and dihydrocapsaicin was observed in cinnamic acid treated cultures, which was 82% and 27.5%, respectively. In the present study, a production of 1.188 mg capsaicin/g DW of placental tissue/day was achieved without the addition of any precursor and a production of 5.78 mg capsaicin/g DW of placental tissue/day by treating with coumaric acid; this was 11-fold higher than in chilli pepper fruit. These results demonstrate successful culture of placenta, the site of synthesis of capsaicin, to boost levels of capsaicin and dihydrocapsaicin in vitro.