XANTHOPHYLLS AND CAROTENES OF DIATOMS, BROWN ALGAE, DINOFLAGELLATES, AND SEA-ANEMONES

¹ Carnegie Institution of Washington, Division of Plant Biology, Stanford University, California

Carotenoid pigments of several groups of algae have been obtained through utilization of the chromatographic adsorption method. The selectivity of this method and the relative positions of the pigments in the columns have been found to vary with the solvents and adsorbents that were employed.

Xanthophylls of algae represent a large proportion of the carotenoid pigments produced in the world's vegetation. Most of the algal xanthophylls were readily convertible, reversibly, into one or more isomers that were separated on the adsorption columns. The principal xanthophylls were the more stable, presumably trans, isomers. Some of the labile isomers also appeared to be normal constituents of the cells. All the algal xanthophylls were unesterified.

The following xanthophylls have been obtained from each of six species of diatoms: diatoxanthin, diadinoxanthin (both new xanthophylls), fucoxanthin, neofucoxanthin A, and neofucoxanthin B. From some eight species of brown algae there were obtained: diatoxanthin (occasionally, in traces), diadinoxanthin (occasionally, in traces), violaxanthin, a flavoxanthin-like xanthophyll, fucoxanthin, neofucoxanthin A, neofucoxanthin B and traces of other xanthophylls. The dinoflagellate Peridinium cinctum and an alga inhabiting a sea-anemone yielded the following xanthophylls: diadinoxanthin, dinoxanthin (a new xanthophyll), neodiadinoxanthin (a new xanthophyll) , neodinoxanthin (a new xanthophyll), peridinin, and two or three isomers of peridinin. A yellow-green alga, Tribonema bombycinum, did not contain fucoxanthin, peridinin or chlorophyll c.

None of the algae examined contained lutein. All the algae examined contained -carotene as the principal polyene hydrocarbon. In only one species, the diatom Navicula torquatum, were appreciable quantities of another carotene e-carotene, observed.

A new xanthophyll, tareoxanthin, was obtained from flowers of the dandelion. A flavoxanthin-like xanthophyll from these flowers may not be identical with flavoxanthin from other sources. Violeoxanthin, a new xanthophyll, was isolated from the flowers of the pansy. Improved methods for the isolation of neoxanthin and violaxanthin from leaves are described. The violaxanthin b of leaves and violaxanthin of pansies are chromatographically identical.

Several groups of xanthophylls with almost identical characteristic spectral absorption curves have now been found. Neoxanthin, tareoxanthin and violeoxanthin fall into one group; violaxanthin, taraxanthin, and dinoxanthin comprise another group; and there are indications of several flavoxanthin-like pigments.

The solvent has a pronounced effect on the shape of the spectral absorption curves of peridinin and of fucoxanthin. In addition to indicating an effect of the solvent on the structure of the pigment molecule, this phenomenon also emphasizes the importance of knowledge concerning the spectral properties of the xanthophylls in the living plant, especially if these spectral characteristics are to be employed in an analysis of the photochemical activity of the plant pigments.

Of the pigments comprising the photosynthetic apparatus, the xanthophylls are subject to the greatest variation. Nearly two dozen of these pigments have been found in the green parts of various plants.