Pittosporumxanthins, cycloaddition products of carotenoids with alpha-tocopherol from seeds of Pittosporum tobira.

A series of carotenoid-alpha-tocopherol cycloaddition products, named pittosporumxanthins B1 ( 3), B2 ( 4), C1 ( 5), C2 ( 6), A3 ( 7), and A4 ( 8), were isolated from the seeds of Pittosporum tobira. The structures were determined to be cycloaddition products of 9' Z-antheraxanthin at the 11' and 12' positions with alpha-tocopherol ( 3 and 4), 9' Z-neoaxanthin with alpha-tocopherol ( 5 and 6), and 9 Z-violaxanthin with alpha-tocopherol ( 7 and 8) on the basis of a detailed analyses of MS and NMR spectroscopic data. The configurations of the carotenoid end groups in the pittosporumxanthins were determined by a modified Mosher's method. Compounds 3, 5, and 7 were assigned (11' R,12' S) and 4, 6, and 8 (11' S,12' R) absolute configurations using CD measurements.