Occurrence of Stereoisomers of 1-(2'-Pyrrolidinethione-3'-yl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic Acid in Fermented Radish Roots and Their Different Mutagenic Properties

Stereoisomers of the tetrahydro-β-carboline derivative, 1-(2'-pyrrolidinethione-3'-yl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (PTCC), were formed from L-trypto-phan with 4-methylthio-3-butenyl isothiocyanate, and their mutagenic properties and contents in different types of the radish products were studied. The isomers were identified as (1S^*, 3S^*, 3'R)-and (1R^*, 3S^*, 3'R^*)-PTCCs ; the former was found as the major compound but had no mutagenic activity, while the latter was mutagenic toward Salmonella typhimurium TA 98 in the presence of a rat microsomal fraction. Both (1S^*, 3S^*, 3'R^*)-and (1R^*, 3S^*, 3'R^*)-PTCC were detected in a ratio of about 4 : 1 in a product fermented for 8 months, but only a trace was apparent in products manufactured within a few weeks.