Sterols,sterol esters and fatty acids of Botrydium granulatum, Tribonema aequale and Monodus subterraneus

The composition of the sterols, sterol esters and fatty acids has been determined in 8-, 11- and 14-day cultures of three members of the Xanthophyceae, Botrydium granulatum, Tribonema aequale and Monodus subterraneus. The main sterols, whether esterified or unesterified, were cholesterol and clionasterol, whose proportions do not vary with age of culture. Much smaller quantities of cycloartenol and 24-methylenecycloartanol were also found in all three algae. The C₁₆ fatty acids are the most common fatty acids in all three algae with C_16:1 being particularly abundant. B. granulatum and T. aequale, however, differ from M. subterraneus in having polyunsaturated C₁₆ fatty acids and a smaller proportion of C_20:5.