a carotenoid beta-end derivative + 2 A => a carotenoid phi-end derivative + 2 AH2
a carotenoid beta-end derivative + 2 a => a carotenoid phi-end derivative + 2 ah2
a carotenoid beta-end derivative + 2 A => a carotenoid phi-end derivative + 2 AH2
a carotenoid beta-end derivative + 2 a => a carotenoid phi-end derivative + 2 ah2