The vitamin B(2) complex of liver: The identity of the liver filtrate factor with pantothenic acid.

IN a previous communication [Macrae et at. 1939] we described the preparation from liver extracts of highly potent concentrates of a nutritional factor for rats to which we applied the name "liver ifitrate factor" [cf. Edgar et al. 1938].; At that time we drew attention to the similarity in properties between this factor and pantothenic acid [Williams et al. 1938; 1939] and discussed the possibility that the two might ultimately prove to be identical. Pantothenic acid was then known to be the fl-alanide of a readily lactonizable hydroxy-acid of unknown constitution and had been shown to be identical with the chick antidermatitis factor [Woolley et al. 1939, 1, 2; Jukes, 1939]. The suggestion that this acid was concerned in rat growth was supported to some extent by other evidence; for example, impure concentrates of pantothenic acid were shown to possess growthstimulating properties for rats [Subbarow &fHitchings, 1939; Oleson et al. 1939]. Preliminary experiments showed that the active material present in our concentrates contained an amide linkage. Using micro-titration methods of the Willstatter-Waldschmidt-Leitz type it was found that destruction of the factor by hydrolysis with dilute alkali caused an increase in the titre of the acid material with alcoholic NaOH, whilst the titre after hydrolysis with dilute acid remained unchanged; this is in agreement with the production during hydrolysis of a readily lactonizable acidic fragment. It was further found that ,3-alanine could be isolated from hydrolysed concentrates of our factor as its ,B-naphthalenesulphonyl derivative, although from the mode of preparation no free ,B-alanine could have been present in the unhydrolysed concentrate. When the lactone portion from these hydrolysed concentrates (itself completely iiiactive in rats in daily doses of about 2 mg.) was coupled with ,B-alanine, using the method employed by Woolley et at. [1939, 2] for regeneration of the chick anti-dermatitis factor, the reconstituted material was found to be fully active when fed to rats in daily doses of about 1 mg. These results correspond with those obtained by Woolley et al. [1939, 1, 2] with the chick factor. We also commenced, in common with many other investigators [Subbarow & Rane, 1939; Babcock & Jukes, 1940; Reichstein & Griissner, 1940*], the synthesis of /3-alanides of various dihydroxyvaleric acids, partly in the hope of obtaining an active substance but more especially with a view to studying the chemical behaviour of mixtures of these compounds. Of the compounds prepared y:&-dihydroxyvaleryl-/3-alanine has not hitherto been described; details of the preparation of its methyl ester are given in the ex perimental section.