Reaction of carotenoids with CCl3OO. by using pulse radiolysis

Abstract

The interactions of carotenoids (bixin, β-carotene and lycopene) with CCl3OO. in aqueous and i-propylalcohol solution saturated with air have been studied by pulse radiolysis. For bixin and β-carotene reaction products from forming process, absorbing in the region of 650 nm, is observed with concomitant carotenoid bleaching (bixin at 500 nm, β-carotene at 450 nm). Their rate constants from forming process are 1.78 ×108 and 7.8 ×107 mol-1 · L · s-1 respectively. However, in the case of lycopene, no such a forming process of reaction as bixin and β-carotene can be observed although there is the bleaching reaction (rate constant 4 ×107 mol-1 · L · s-1). The results suggest that the carotenoid radical cation and an additional radical are produced in the case of bixin and β-carotene, whereas lycopene undergoes electron transfer with CCl3OO., forming cation radical.