Regulation of Capsaicin Synthesis in Cultured Cells of Capsicum frutescens

Abstract

Capsaicin belongs to a group of phenolic compounds the capsaicinoids. These molecules, which are the end products of metabolism, are responsible for the hot taste in the mature fruits of the chilli pepper, Capsicum frutescens (Yeoman et al. 1980). They have a modest commercial value and at today’s prices one kilogram of the oleoresin would be worth about £450. Apart from the commercial implications there are certain features of capsaicin, its synthesis and accumulation, which form an attractive basis for those wishing to work with a system to explore the regulation of secondary product biosynthesis in general. For example, capsaicin, the predominant capsaicinoid in fruits, constitutes about 70% of the total with dihydrocapsaicin at about 28%. These capsaicinoids are only synthesized and accumulated in the maturing fruit at one particular stage of development, and have not been detected in other parts of the plant (Holden et al. 1987a). Indeed, all attempts to demonstrate capsaicin synthesis in leaves, stems or roots have so far failed (Holden et al. 1988a,b). From this it can be seen that a highly focussed approach is possible as the site and timing of capsaicin synthesis are known and the product is stable.