Carotenoids of Sea Squirts. I. New Marine Carotenoids, Halocynthiaxanthin and Mytiloxanthinone from Halocynthia roretzi

Abstract

New marine carotenoids, halocynthiaxanthin (4) and mytiloxanthinone (5), were isolated from the sea squirt, Halocynthia roretzi ("Maboya" in Japanese). The structures of 4 and 5 were established to be (3S, 5R, 6S, 3'R)-5, 6-epoxy-3, 3'-dihydroxy-7', 8'-didehydro-5, 6, 7, 8-tetrahydro-β, β-caroten-8-one and 3, 8'-dihydroxy-7, 8-didehydro-β, κ-carotene-3', 6'-dione, respectively.