Effects of Pyrogallol on O-Methylation of Dopamine and Salsolinol

Abstract

In the cultured cells of Corydalis pallida var. tenuis, the formation of 6-O-methylated metabolites (6-D4 and 6-D7) from salsolinol-D4 (2-D4) was reduced by pyrogallol. The production of 3-O-methylated derivatives (10 and 10-D3) from dopamine was almost not affected by pyrogallol. Similar results were obtained in intact plants, though the effect of pyrogallol on methylation of C-6-OH of salsolinol in plants is smaller than that in the cultured cells. These results show that the effects of pyrogallol on the methylation of C-6-OH of salsolinol and that on the methylation of C-3-OH of dopamine are different, suggesting that the O-methylating enzymes of salsolinol and dopamine are different in C. pallida var. tenuis. The production of 3-O-methyldopamine in the presence of pyrogallol was reduced in intact plants of Cynanchum vincetoxicum, but not in the cultured cells. The effect of pyrogallol on the methylation of salsolinol was uncertain in Cyn. vincetoxicum. Both 6- and 7-O-methylations of salsolinol occur in Cyn. vincetoxicum, while only 6-O-methylation occurs in C. pallida var. tenuis. This could reveal that the O-methylating enzymes at C-6 and C-7 are different.