Synthesis of 1-Methylindole-3-Acetaldehyde and Its Oxidation by Horseradish Peroxidase

摘要

1-Methylindole 3 acetaldehyde (1 methyl IAA1d) was synthesized in my laboratory from 1 methyltryptophan by interaction of the amino acid with dilute hypochlorite solution. 1 Methyl IAA1d was obtained in the form of bisulfite salt and the free aldehyde was a colorless syrupy liquid. It gave positive tests to Schiff and hydrazine reactions for aldehyde and to Salkowski, Ehrlich and xanthydrol reactions for indole. The I.R. spectrum of the freshly released 1 methyl IADD1d bears a great similarity to that of indole 3 acetaldehyde (IAA1d) except the NH stretching band at 3390/cm is absent. 1-Methyl-IAA1d shows strong to medium-strong bands at 1720, 1470, 1430, 1370, 1335, 1250, 1160, 1130, 1070, 1015 and 740/cm and the typical indole absorption at 288 nm. The structure of the aldehyde was further confirmed by elementary analysis. Oxidation of 1-methyl-IAA1d by horseradish peroxide at acidic pH gave 1 methylindole 3 carboxaldehyde (1-methyl-IAa1d) as the major product. The enzyme was not active in oxidation of 1 methyl IAA1d at pH above 6.0. At alkaline pH, bisulfite stimulated the catabolism of the aldehyde. However, unlike IAA1d, peroxidation of 1-methyl-IAA1d did not yield 1-methyl-4-hydroxyquinoline as a major product at pH above 6.0.