Isolation of the Bound Form of Nicotinic Acid

Abstract

Chaudhuri and Kodicek¹ have shown that almost the whole of the nicotinic acid in cereal bran was present in a bound form. They concentrated this ‘precursor’ of nicotinic acid from wheat bran considerably. Chaudhuri², starting from rice bran in this laboratory, concentrated this substance about seventy times, following the concentration by the usual colorimetric method using p-aminobenzoic acid as the coupling reagent³. It has now been possible to isolate the bound form of nicotinic acid from rice bran in a crystalline state. This work has been facilitated by the observation that the active substance, when subjected to paper chromatography using phenol–water (80 : 20) as the solvent system, gave two ninhydrin-sensitive spots, one of which moved with the solvent front and produced a blackish-violet colour with ninhydrin. It also gave an orange colour when sprayed with p-aminobenzoic acid after exposure to cyanogen bromide vapour according to the method of Kodicek and Reddi⁴. The orange colour has been shown to be produced by the bound form, and it is insoluble in amyl alcohol, which dissolves the colour produced by free nicotinic acid as observed by Swaminathan⁵. A method developed by Das and Ghosh⁶ based on this observation has been used to follow the concentration of the bound form of nicotinic acid in the present work.