Formation of Yellow Pigment Containing a β-Carboline Skeleton in Salted Radish Roots and its Properties

Abstract

The presence of a yellow pigment containing a β-carboline derived from 1- (2'-pyrroli-dinethion-3'-yl) -1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (PTCC) was investigated in salted radish roots. PTCC spotted onto silica gel plates was allowed to stand for five days at 40°C, resulting in the generation of yellow pigments. The methanol extract was subjected to Toyopearl HW-40 S column chromatography using methanol as an eluent. The major peak was concentrated to give a yellow powder. The UV, IR and NMR spectra showed that the yellow compound had a β-carboline moiety derived from PTCC by its decarboxylation. On the other hand, yellow pigments extracted from salted radish roots were fractionated on a Sephadex LH-20 column using 50% methanol as an eluent. Among three fractions, the main yellow fraction was isolated and analyzed by paper chromatography, UV and IR spectroscopy. These data showed that the yellow pigment was similar to those of yellow pigment derived from PTCC. Thus, it was confirmed that PTCC contributed to the development of abright yellow pigment in salted radish roots. Effect of light resistance on the pigment was similar to that of curcumin. However, the color of the pigment was slightly turned to a brown with 1 mM ferrous ion. Also, the pigment exhibited no mutagenic activity to S. typhimurium TA 98 and TA 100 with and with out S-9 mixture.