STEROLS OF SOME MARINE PRYMNESIOPHYCEAE

Sterols were identified in six marine prymnesiophyte isolates, some of which appear to have value as bivalve food. The principal sterol in P leurochrysis carterae (Milford #961) and an unidentified prymnesiophyt e (CCMP1215) was 24-methylcholesta-5,22-dienol, a common sterol in pry mnesiophytes. Isolates CCMP594, CCMP609, and CCMP459 contained either 24-ethylcholesta-5,22-dienol or 24-ethylcholest-22-enol as the major s terol. In addition, Pavlova pinguis (CCMP609) and Pavlova sp. (CCMP459 ) contained the unusual dihydroxysterols 24-methylpavlovol and 24-ethy lpavlovol, which have been found only in members of the Pavlovalves. P rymnesium parvum contained cholesterol without traces of other sterols . Compared to the other isolates, the quantity of sterols was extremel y low in P. parvum.