Effect of sterols on the permeability of alcohol-treated red beet tissue.
Alcohols and hydrogen peroxide altered the permeability of membranes of Beta vulgaris root cells. Generally alcohols increased the permeability of membranes without going through an induction period except methanol which required a 10- to 15-hour induction period. The membrane effect of methanol could be inhibited with CaCl(2), cholesterol, beta-sitosterol, and stigmasterol. Cholesterol was the most effective inhibitor, followed by beta-sitosterol and stigmasterol; and at the same concentration, the sterols were more effective than CaCl(2), the classic membrane stabilizer.Ergosterol increased the methanol-initiated betacyanin leakage. Since none of the tested sterols reversed the betacyanin efflux induced by hydrogen peroxide, the sterols do not apparently act as antioxidants. The results are explained in terms of sterol-phospholipid interaction, based on stereochemistry and charge distribution.
Grunwald
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Department of Agronomy, University of Kentucky, Lexington, Kentucky 40506.