Quantitative Estimation of Lactoflavin and of Vitamin B 6 in Cow's Milk and in Human Milk

Abstract

It has been shown 1 that vitamin G as needed by the rat contains at least 2 major components: lactoflavin and vitamin B₆, the lack of the latter being associated with specific skin lesions (“rat pellagra” or, rather, “rat acrodynia” 2 ).

By feeding to rats a vitamin B-free diet complemented by vitamin B proper, the antineuritic factor (B₁), and lactoflavin, or by vitamin B₁ and a vitamin B₆ concentrate, it was possible to obtain quantitative data^{2, 3} concerning the distribution of lactoflavin and vitamin B₆ in different foodstuffs. For the estimation of the lactoflavin values, the basal vitamin B-free diet was supplemented by crystalline (or highly purified) vitamin B₁ (3 international units daily) plus vitamin B₆ concentrate. For the estimation of vitamin B₆ values, vitamin B₁ was similarly provided but supplemented by pure lactoflavin (10 γ daily). The vitamin B₆ concentrate consisted of a yeast preparation such as may be obtained according to the method of Peters, et al., 4 by adsorption of a yeast extract on charcoal and subsequent elution with alcohol containing hydrochloric acid. It has been found that 1 cc. of this so-called Peters' eluate is equivalent to about 1 “rat-day dose” of vitamin B₆.

The values for lactoflavin were determined by means of the growth test, skin symptoms being too irregular and frequently insufficiently obvious. The “rat-day dose,” taken as provisional unit, was defined as the minimum quantity of the substance which would give rise to a gain in weight of about 10 (9 to 11) gm. per week for at least 4 weeks.

The values for vitamin B₆ were based directly on the curative effect against dermatitis.