THE CHEMICAL ISOLATION OF VITAMINES

Abstract

The existence of at least three vitamines, namely the antiscorbutic, the so called fat-soluble, and the antineuritic, is known at the present time.This paper deals principally with the antineuritic vitamine.The important stage in the chemical investigation of this substance began with the classical research of Eijkman in 1897, who was able to show that rice polishings contain the antineuritic vitamine and that this substance is dialyzable and not precipitated from its solution by alcohol.Eijkman's work stimulated Funk to attempt the chemical isolation of the substance.In a series of researches he established the following facts.First of all he found that the curative substance is of a simple nature, as yeast can be hydrolyzed for 24 hours with 25 per cent sulfuric acid without causing the destruction of its vitamine.The active substance is precipitated by phosphotungstic acid and is mainly found in the silver nitrate-baryta fraction, when subjected to silver precipitation.This fraction contains three classes of biological products; namely, the histidine, pyrimidine, and nicotinic acid groups.On working up these fractions from yeast Funk isolated three substances which on analysis yielded the following formulas: C24H1909N5, C23H2309N5, and C6H502N (nicotinic acid).By using the same or similar methods, Suzuki, Shimamura, and Odake, Vedder and Williams, and E&e, Evans, Moore, Simpson, and Webster were also able to isolate more or less active vitamine fractions from active raw material.Similar fractions were obtained by Funk from milk, brain, lime juice, rice polishings, and cod liver oil.