FACTORS IN POTENCY OF THYMUS EXTRACTS

Abstract

ROWNTREE, CLARK AND HANSON (i) reported their first extract of calves' thy mi as containing 15.8 mg. reduced and oxidized sulphur compounds (calculated as glutathione) per 100 cc. They further stated their extract to be “extremely stable and entirely potent and satisfactory for injection in rats even after being kept at room temperature for 2½4 to 4 years.“ Later attempts (2) to prepare an extract of the same stability were apparently unsuccessful. First extracts prepared in this laboratory by Hanson's method had a sulphydryl content equivalent to 40 to 50 mg. glutathione per 100 cc. Later adopting Steinberg's method (3) the sulphydryl content was raised to around 200 mg. per 100 cc. Kept at room temperature in tightly stoppered vessels, the sulphydryl content dropped be-low 16 mg. per 100 cc. in 15 days. At the same temperature but with the vessels closed by loose cotton plugs, a similar drop required only 5 days.