Structures of tobiraxanthins A1, A2, A3, B, C and D, new carotenoids from the seeds of Pittosporum tobira

Six new carotenoids, named tobiraxanthins A1–A3, B, C and D, have been isolated from the seeds of Pittosporum tobira. Their structures were elucidated by NMR and MS spectral analyses. The chemical relation of the tobiraxanthins to the previously reported carotenoids having a 4-acetyl-3-methoxycyclopentene ring was also studied.