Synthetic regulators of carotenoid biosynthesis in Citrus paradisi

Abstract

The ability of 16 amines to induce carotenoid biosynthesis in Marsh seedless grapefruit is correlated with the octanol-water partition coefficient and the Hammett constants. The compounds fall into three series: p-RC 6H 4COOCH 2CH 2NEt 2 (R = H, NH 2, CN, NO 2, MeO, Me, tert-Bu, F, Cl, Br), p-RC 6H 4CH 2NEt 2 (R = H, Me, NO 2), and RC 6H 4OCH 2CH 2NEt 2 (R = o-Me, m-Me, p-Me). Total carotene content increased up to 12-fold. Lycopene, not normally accumulated, became a major pigment. The benzoates caused up to a 24-fold increase in the β-carotene content. Except for the larger accumulation of cyclic carotenes, the mode of action of these amines appears to be similar to that of 2-(4-chlorophenylthio triethylamine hydrochloride.