A rapid method of preparing the anti-diabetic substance of pancreas

Abstract

As reported 1 at the last meeting of this branch, heating to 75° and 80° C. for one-half hour does not destroy the anti-diabetic substance extracted in acid aqueous media. The original observation of Murlin and Kramer that a potent extract could be prepared by boiling dog's pancreas in 0.2N HCl was confirmed 2 some time ago. Recently we have compared the yield of rabbit units obtained on the one hand by grinding macerated pancreas in 0.2N HCl in a bacteria grinder for 15 hours and, on the other hand, by heating to 75° C. for one hour or bringing just to boiling temperature.

Kimball, Piper and Allen 3 showed also at the last meeting that the active substance is precipitated by complete saturation with sodium chloride, and with either of the alcohols, methyl, propyl, butyl or amyl when added to a solution in 80 per cent. ethyl alcohol. For example, preparation No. 140, heated in 0.2N HCl to 75° C, cooled, strained through cheese cloth, neutralized to P_H of 4.1, and filtered, gave in two tests representing 10 gms. pancreas each, a fall of blood-sugar in normal rabbits of 44 and 62 milligrams. The second day the filtrate was precipitated by saturation with sodium chloride, the precipitate taken up in 70 per cent. alcohol, centrifuged to remove insoluble protein and reprecipitated with 5 vols. amyl alcohol. The excess of amyl alcohol was evaporated off before a fan and the residue taken up in sterile water. Equivalent doses representing 10 grams pancreas now gave drops in blood-sugar in rabbits of the same size of 77 and 74 milligrams showing that all the potency had been removed. The filtrate from the NaCl precipitate contains no active substance.