Free and esterified sterols of cotton buds and anthers

Capillary gas liquid chromatography analyses were conducted on free and esterified sterol fractions of cotton (Gossypium hirsutum cv. Stoneville 213) floral buds and anthers. The free sterols of both cotton buds and anthers consist mainly of the common plant sterols sitosterol, stigmasterol and 24ζ-methylcholest-5-en-3β-ol. The composition of esterified sterols of cotton buds and anthers were similar, and consisted of pollinastanol, 31-norcycloartanol, cycloartenol, 31-norcycloartenol, 24-dehydropolinastanol and sitosterol. Desmosterol was also present in both the free and esterified sterols of anthers. The identities of the sterols were confirmed by gas chromatography-mass spectrometry analyses. Esterified sterols accounted for 46.7 and 88.7% of total sterols of cotton bud and anthers, respectively. The ratio of esterified sterol to free sterol per gram of tissue is about 8∶1 in anthers. The Δ5-sterols of the esterified sterols of cotton buds and anthers account for only 17 and 9.2% of the total sterols, respectively.