Studies on the chemistry of cod liver oil. II. A cod liver oil concentrate manifesting both antirachitic and antiophthalmic properties. ∗

Abstract

In recent years, the demonstration of the specificity of cod liver oil for rickets has provided a stimulus for further attempts to isolate and identify the active principle of the oil. Though the goal has not been reached, nevertheless appreciable progress has been reported by various investigators.

The problem has been approached by devious routes, but the most promising finding has been the demonstration that the vitamines known to be present in cod liver oil—the antirachitic and antiophthalmic—are to be found in the ether-soluble, non-saponi-fiable portion of the oil.

On saponifying cod liver oil, Steenbock, Nelson and Hart 1 obtained a product that was curative for both rickets and ophthalmia. Using an analogous process, Zucker, Pappenheimer and Barnett 2 and also Takahashi 3 reported results somewhat like those of Steenbock, Nelson and Hart. Some time later, Zucker 4 extracted cod liver oil with alcohol and then saponified the alcoholic extract. He thus obtained a product which contained only the antirachitic vitamine, the antiophthalmic vitamine having been destroyed in the procedure.

By means of a special extraction and saponification process we have prepared from cod liver oil a concentrate manifesting both antirachitic and antiophthalmic activity. The residual cod liver oil is entirely free from vitarnines.

The crude concentrate-0.5 grn. from 1000 gm. cod liver oil is obtained as a brown syrupy mass which, on standing, crystallizes in light yellowish brown needle-like crystals radiating from a central point.

This highly concentrated substance, which is insoluble in water but freely soluble in the ordinary organic solvents, contains practically all of the antirachitic and antiophthalmic vitarnines originally present in the fresh cod liver oil.

In other words, if this 0.5 gm. vitamine concentrate is incorporated in 1000 gm. cottonseed oil, the resultant product is practically equivalent in vitamine activity to the original cod liver oil.