Observations on the liver filtrate factor of the vitamin B2 complex

Abstract

The liver filtrate factor was not adsorbed even on exhaustive treatment of liver extracts with fuller''s earth but was adsorbed by norite charcoal. The factor has acidic properties, being extracted by ether and amyl alcohol from acidified solns. but only partially extracted by amyl alcohol from neutral solns. Salts of Pb, Hg, Ag, quinine and brucine did not precipitate the factor but it was precipitated by phosphotungstic acid and Ba hydroxide from alcoholic solns. Treatment with acetic anhydride yielded a chloroform soluble acetyl derivative with but little biological activity; the activity was recovered by hydrolysis of the acetyl derivative. The biological activity of the factor was unaffected by treatment with diazomethane. The most potent concentrate obtained contained the rat day dose of the factor associated with 180 [mu]g. of solids.