S‐Methyl‐L‐Cysteine Sulf oxide as the Precursor of Methyl Methanethiolsulfinate, the Principal Antibacterial Compound in Cabbage

Abstract

ABSTRACT S‐Methyl‐L‐cysteine sulfoxide (SMCSO) was present in several cultivars of cabbage ( Brussicn oleracea ) at 690–1,120 ppm. SMCSO was not inhibitory to Leuconostoc mesenreroides , but its hydrolysis product, methyl methanethiolsulfinate (MMTSO), was inhibitory. MMTSO was formed in fresh cabbage juice (CJ) and in a model system containing SMCSO and fresh cabbage (pH 4.0) precipitate, perhaps by cysteine sulfoxide lyase. Growth inhibition by 1 mM MMTSO was reversed by 5 mM dithiothreitol, cysteine, or reduced glutathione, but not by oxidized glutathione or thiamine.