Isolation of Stereoisomeric Epoxy Carotenoids and New Acetylenic Carotenoid from the Common Freshwater Goby Rhinogobius brunneus

Abstract

Stereoisomeric epoxy carotenoids with 3,5-cis configuration, diadinoxanthin B [(3S,5S,6R,3'R)-diadinoxanthin] (1) and antheraxanthin B [(3S,5S,6R,3'R)-antheraxanthin] (2), along with diadinoxanthin A [(3S,5R,6S,3'R)-diadinoxanthin] and antheraxanthin A [(3S,5R,6S,3'R)-antheraxanthin], were isolated from the common freshwater goby Rhinogobius brunneus. This is the first example in nature of 3,5-cis carotenoid epoxides. Furthermore, a new acetylenic triol carotenoid, gobiusxanthin (3), was obtained, and its structure was determined to be 7,8-didehydro-beta, epsilon-carotene-3,3', 6'-triol by chemical and spectral data.

Carotenoids in Marine Animals

“…Carotenoids with a 3,6-dihydroxy-ε-end group, salmoxanthin ( 7 7 ), deepoxysalmoxanthin ( 7 8 ) (from the salmon Oncorhynchus keta ) [40], and gobiusxanthin ( 7 9 ) (from the freshwater goby Rhinogobius brunneus ) [41], were isolated. A series of carotenoids with a 7,8-dihydro- and/or 7,8,7′,8′-tetrahydro polyene chain were isolated from the integuments and eggs of the Japanese common catfish Silurus asotus [42].…”

Structure of Minor Carotenoids from the Crown-of-Thorns Starfish, Acanthaster planci

“…The relative configuration of the 3′,6′-dihydroxy-ε-end group in 3 was elucidated by performing a NOESY experiment. In the cases of gobiusxanthin, 16 salmoxanthin, 17 and deepoxysalmoxanthin, 17 which have a 3′,6′-cis-dihydroxy-ε-end group, NOESY correlations for H-16′/H-3′ and H-16′/H-7′ were observed. 17 However, the NOESY correlation for H-16′/H-3′ was not noted in 3, as shown in Figure 1.…”

“…18 As with gobiusxanthin, 3 showed a negative Cotton effect around 280 nm in the CD spectrum, indicating a 6′R configuration. [16][17][18] Therefore, the structure of 3 was determined to be (3R,3′R,6′R)-7,8-didehydro-,ε-carotene-3,3′,6′-triol, and the compound was named 3′-epigobiusxanthin. Compound 4 showed UV-vis absorption maxima at 405, 430, and 460 nm.…”

Structures of Minor Carotenoids from the Japanese Common Catfish, Silurus asotus

“…3,4) Tunaxanthin and alloxanthin were also assumed to originate from dietal small fish such as goby. 16) In conclusion, the new carotenoids, 7Ј,8Ј,9Ј,10Ј-tetrahydro-b-cryptoxanthin (7), 7Ј,8Ј-dihydrodiatoxanthin (8), and (3S,6S,6ЈS)-e-cryptoxanthin (9) were isolated from the skin, fins, and gonads of S. asotus as minor components. Furthermore, 9Z and/or 9ЈZ geometrical isomers of parasiloxanthin, 7Ј,8Ј-dihydroparasiloxanthin, and 7Ј,8Ј-dihydro-b-cryptoxanthin were characterized by 1 H-NMR.…”