A New Method for the Estimation of Trigonelline in Urine and Foodstuffs

Abstract

THE recognition of trigonelline as a product of the metabolism of nicotinic acid is due to Ackermann¹, who in 1912 dosed dogs with nicotinic acid and found it to be partly excreted as trigonelline. Linneweh and Reinwein^2,3 isolated the latter substance from normal human urine, and found that the amount excreted was increased after the consumption of coffee. More recently Sarett, Perlzweig and Levy⁴ reported that when human subjects were dosed with nicotinic acid, a portion of it, ranging from 10 to 15 per cent, was excreted as trigonelline. Melnick, Robinson and Field⁵ have made similar observations. However, the exact relation between the excretion of trigonelline and intake of nicotinic acid remains to be investigated, and can only be settled after a satisfactory quantitative procedure for the estimation of trigonelline has been devised. The methods used by Sarett and his co–workers and by Melnick et al., involve the conversion of trigonelline to nicotinic acid in the presence of strong alkali and ammonia. The conversion according to the former group of workers is 65–75 per cent, and according to the latter group 28–38 per cent. The amount converted seems to depend on the concentration of ammonium salts, the strength of alkali used, the length of hydrolysis, and possibly other factors, and the method at best is only semi–quantitative.