Investigations on vitamin B2

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Abstract
I. Aqueous extracts of various materials, when tested for vitamin B2, demonstrated that the minimum daily dosages were equivalent to 0.3 gm. fresh liver, 0.4 gm. dry milk-powder, 0.7 gm. bakers'' yeast, and 1.4 gm. of brewers'' yeast. Extract of beef muscle was almost inactive. Eli Lilly''s commercial liver-concentrate was highly potent.[long dash]II. Extracts of fresh ox-liver and of brewers'' yeast autoclaved 3 hrs. at 124-125[degree] at pH 9.0 lost 75% and 90% respectively of the initial activity. Commercial liver-concentrate lost none. Extract of brewers'' yeast, heated at a pH of 6.25, also lost no activity. The stability of vitamin B2 to heat and alkali is probably connected with some kind of protective material.[long dash]III. Indications are that vitamin B2 is neither basic nor acid. It is not precipitated or inactivated by nitrous acid. It is adsorbed on norite at pH 4.6. The symptoms of vitamin B2 deficiency could not be ameliorated by hemin, hemoglobin, or lactalbumin.