Free and esterified sterols of the marine dinoflagellate Gonyaulax polygramma [Algae]

Free and esterified sterols of the common marine dinoflagellate Gonyaulax polygramma were identified using capillary gas chromatography—mass spectrometry (GC‐MS). Fractions containing free 4α‐methyl and 4‐desmethyl sterols were isolated by column chromatography and shown to consist of at least 20 components. Major sterols included 4α,23,24‐trimethyl‐5α‐cholestan‐3β‐ol (dinostanol), 4α,23,24‐trimethyl‐5α‐cholest‐22E‐en‐3β‐ol (dinosterol), cholest‐5‐en‐3β‐ol (cholesterol), 23,24‐dimethyl‐5α‐cholest‐22E‐en‐3β‐ol and 23,24‐dimethylcholesta‐5,22E‐dien‐3β‐ol. Although the same group of sterols was found in the free and esterified sterol fractions, the proportions of individual sterols were quite different. The complexity of the sterol distributions, together with the predominance of dinostanol, distinguishes the sterol composition of this alga from those of other members of the Gonyaulacaceae .