STEROLS OF CEPHALEUROS (TRENTEPOHLIACEAE), A PARASITIC GREEN ALGA1

ABSTRACT 24‐Ethylcholesterol, 24‐ethylcholesta‐5,7,22‐trienol, dihydrolanosterol, 24‐ethylcholesta‐7,22‐dienol, and 4‐methyl‐24‐ethylcholesta‐7,22‐dienol were identified in cultured Cephaleuros in small quantities. Cholesterol made up 19% of the total sterol. The principal sterol, making up 65% of the total sterol, was 4,24‐dimethylcholest‐7‐enol, a new algal sterol. This is the first report of this sterol as the principal sterol of any living organism.