Isolation and identification of a novel .BETA.-carboline derivative in salted radish roots, Raphanus sativus L.

The methanol extract of salted radish roots contains several precursors of yellow pigment. The main compound was isolated by the use of Toyopearl HW-40S column chromatography, and its structure was determined to be 1-(2'-pyrrolidinethion-3'-yl)-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid on the basis of an elemental analysis, and IR, UV, FAB-MS and NMR spectroscopy. This compound is presumed to have been the condensation product from the degradation of 4-methylthio-3-butenyl isothiocyanate and L-tryptophan. This carboline compound is considered to play an important role in the formation of the yellow pigment in salted radish roots.