“…The trollein formula has not as yet been elucidated, but it may be an allenic derivative of a-carotene triol, with the formula 3,3',5'-trihydroxy-6',7'-dehydroa-carotene. Such a pigment is not discussed in Weedon's recent review about allenic carotenoids (Weedon, 1969), but the suggested formula would be in accord with its properties-the same chromophore as neoxanthin-having the cu-ionone ring instead of the 5,6-epoxidic violaxanthin ring. Its structure will be further investigated.…”