PRECURSOR BIOTRANSFORMATION IN IMMOBILIZED PLACENTAL TISSUES OF CAPSICUM-FRUTESCENS MILL - II - INFLUENCE OF FEEDING INTERMEDIATES OF THE CAPSAICINOID PATHWAY IN COMBINATION WITH L-VALINE ON CAPSAICIN AND DIHYDROCAPSAICIN ACCUMULATION

Increased yields of capsaicin and dihydrocapsaicin, major pungent prin ciples of chilli pepper fruit, were obtained when immobilized placenta l tissues of Capsicum frutescens were treated with intermediate metabo lites of the capsaicinoid pathway, i.e. 1-phenylalanine, t-cinnamic ac id, p-coumaric acid, caffeic acid, ferulic acid and vanillylamine in c ombination with 1-valine. Although vanillylamine and 1-valine are the nearest precursors to capsaicin, their addition to immobilized placent a did not significantly affect the accumulation of capsaicin. Maximum capsaicin and dihydrocapsaicin accumulation was achieved on p-coumaric acid + 1-valine treatment. Maximum percentage of bioconversion was ob served in culture treated with t-cinnamic acid + 1-valine. In nature, the ratio of the principle components - capsaicin and dihydrocapsaicin - is about 2:1. In immobilized placental tissues fed with precursors, the ratio of capsaicin and dihydrocapsaicin varied between 2.2:1 to 3 .7:1 compared with the ratio of 2:1present in natural chilli pepper fr uit. A productivity of 3.072 mg capsaicin/gDW/day was obtained by crea ting with p-coumaric acid + 1-valine, which was 514% higher than that of chilli pepper fruit. These results successfully demonstrate the use of placental tissue, the site of synthesis of capsaicin, to enhance y ields of metabolites in vitro using a combined precursor treatment.