Chloroplast pigments of the marine dinoflagellateGyrodinium resplendens

Abstract

The photosynthetic marine dinoflagellate,Gyrodinium resplendens, was grown axenically and harvested during logarithmic growth for analysis of its lipid‐soluble pigments. Chlorophylla and 8 carotenoids were isolated from the methanol and acetone extract by column and thin‐layer chromatography. Chlorophyllc was isolated by partitioning the total extract between saline aqueous acetone and hexane.Absorption spectra taken in hexane, ethanol, methanol and carbon disulfide confirm the presence of β‐carotene, peridinin, dinoxanthin and diadinoxanthin as major carotenoids.Four new minor xanthophylls are also described, one of which, namedpyrrhoxanthin, resembles an alkali‐labile keto‐epoxide. At least one of the minor xanthophylls occurs as an ester.Diadinoxanthin fromGyrodinium and antheraxanthin fromEuglena gracilis seem to be identical with respect to absorption curves, polarity, number of 5, 6‐epoxy groups and lack of allylic hydroxyl groups; however, co‐chromatography of stereoisomers after iodine‐isomerization showed slight differences.Most of the carotenoids are further characterized here by their partition ratios between hexane and 95% methanol. Several of the carotenoids were tested for the presence of 5, 6‐epoxy and allylic hydroxyl groups. Four of the pigments, comprising 91% of the total carotenoids are revealed as 5,6‐monoepoxides by their instability toward dilute acid. One carotenoid resembles a diepoxide