Sterol-Content Lowering Action of o-Chlorobenzylchloride in Yeast1

o-Chlorobenzylchloride, a simple aromatic halogen compound, was found to inhibit the growth of Saccharomyces cerevisiae and to lower the contents of sterols and fatty acids. The growth inhibition was considerably alleviated by the presence of sterols such as ergosterol and cholesterol and of unsaturated fatty acids such as oleate and linolenate. Inspection of effect of the inhibitor on the electron transport system related to the biosyntheses of these com-pounds revealed that the cytochrome contents and some enzyme activities in the system of the inhibited cells were much lower than those of the control cells. The features of the inhi-bition were similar to those of inhibition for other organisms by the hypocholesterolemic compounds such as triparanol and benzmalecene. Cholesterol content of mammals is known to be lowered by hypocholesterolemic compounds such as triparanol, benzmalecene and triarimol (1, 2). It has been reported that lanosterol accumulates in liver of triarimol-treated rat (2) and that respi-ration of submitochondrial particulates of beef heart is inhibited by progesterone or azasteroid <5). These compounds also inhibit the growth of microorganisms such as yeast (4), Ustilago maydis (5), and Tetrahymena (6, 7). The inhibition is •alleviated by sterols and fatty acids, especially by unsaturated fatty acids. These compounds have been reported to inhibit the biosyntheses at the steps of unsaturation of fatty acids and sterols (4), •demethylation of lanosterol (6) and reduction of J"i«>-double bond of sterols (6). No further study has been made on the mechanism for th