Robert C. Tuttle's research while affiliated with Norwegian Institute of Wood Technology and other places

1.1. The carotenoids of seven selected chrysophycean algae (Ochromonas sp., Poterioochromonas malhamensis, Olisthodiscus luteus (two strains), Synura petersenii, Chromulina ochromonoides and Sarcinochrysis marina) were analysed quantitatively and identified by methods including mass spectrometry.2.2. β,β-Carotene was invariably present. The allenic fucoxanthin was always the major carotenoid, occasionally accompanied by small amounts of its desacetyl derivative, fucoxanthinol, and the allenic epoxide neoxanthin.3.3. Common accessory carotenoids comprised zeaxanthin, its monoepoxide antheraxanthin (one source only) and its diepoxide violaxanthin. Sarcinochrysis marina, also a chrysophyte (sensu-stricto) differed from this pattern in that the minor accessory carotenoids occurring with fucoxanthin and β,β-carotene were the acetylenic diatoxanthin and diadinoxanthin, which are typical prymnesiophyte carotenoids.4.4. It is concluded that the Chrysophyceae have a rather characteristic carotenoid pattern different from that of many algal classes. However, a distinct separation of the Chrysophyceae from the Prymnesiophyceae on the basis of carotenoid composition is not always possible.

The heterotrophic dinofiagellate, Crypthecodinium cohnii, cultured in a nutrient medium containing methionine-[CD3] incorporated deuterium into the newly synthesized 4α-monomethyl compound dinosterol (4α,23,24-trimethylcholest-22-en-3β-ol). The MS fragmentation pattern indicated that the C-23 methyl group contained three deuterium atoms and was introduced intact by transmethylation from methionine. The C-24 methyl group contained only two deuterium atoms which is consistent with the production of a 24-methylenesterol intermediate which is subsequently reduced to give the 24-methyl side chain. Mechanisms are proposed to account for the production of the dinosterol side chain.

The heterotrophic dinoflagellate Crypthecodinium cohnii contained the 4α-methyl sterols, dinosterol, dehydrodinosterol (4α,23,24-trimethylcholesta-5,22-dien-3β-ol) and the tentatively identified 4α,24-dimethyl-cholestan-3β-ol and 4α,24-dimethylcholest-5-en-3β-ol. The major 4-demethyl sterol was cholesta-5,7-dien-3β-ol which was accompanied by a smaller amount of cholesterol and traces of several other C27,C28 and C29 sterols. In addition, a 3-oxo-steroid fraction was isolated and the major component identified as dinosterone (4α,23,24-trimethylcholest-22-en-3-one). The possible biosynthetic relationships of these compounds are discussed.