ABSTRACT
Phytostanols are a completely saturated subgroup of phytosterols and lack the carbon-carbon double bonds found in cholesterol and phytosterols [1-5] (Figure 36.1). Saturated plant sterol derivatives (campestanol and sitostanol) are produced by the hydrogenation of sterols and are not abundant in nature. Chemical hydrogenation reduces all double bonds, that is, from sitosterol and stigmasterol to sitostanol, and campesterol and brassicasterol to campestanol [6]. The conversion of campesterol into campestanol involves a three-step process that includes 24-methylcholest-4-en-3β-ol, 24-methylcholest-4-en-3-one, and 24-methyl-5α-cholestan-3-one as intermediates [7]. Moreover, when seeds from transgenic cotton plants were analyzed for levels of 3-hydroxysteroid oxidase and sterol composition, a direct correlation between enzyme levels and phytostanol levels was observed, suggesting that the enzyme is responsible for formation of the latter [6].
