IN-VITRO REACTION OF L-TRYPTOPHAN AND VITAMIN-B-6 - SYNTHESIS OF THE CORRESPONDING BETA-TETRAHYDROCARBOLINES

The L-tryptophan load test is used to study vitamin Bg deficiency in animals. This test might suffer from an inherent defect due to the possible nonenzymatic formation of cyclic compounds between L-tryptophan and pyridoxal or pyridoxal 5'-phosphate. In this paper the synthesis, under physiological conditions (pH 7.0 and 37 degrees C), of the cyclic compounds (beta-tetrahydrocarbolines) formed from L-tryptophan and pyridoxal or pyridoxal 5'-phosphate is reported. The in vitro formation of these compounds has been implied for many years through evidence from biological experiments and ultraviolet absorption spectra. The synthesized compounds will be valuable to investigators studying their possible formation in animals, their toxicity, and their possible inhibition of certain pyridoxal 5'-phosphate requiring enzymes.