Crystalline vitamin D.

摘要: In two earlier papers in these ‘Proceedings’ (Askew et al ., 1930, a ; Angus 1931) crystalline antirachitic substance was described, obtained by vacuum distillation of the products irradiation ergosterol. second paper, physical properties and activities number successive preparations this product were recorded, it shown that sufficiently constant to suggest consisted mainly one substance. We avoided conclusions yet pure, showing distinct variations which suggested other, presumably inactive, substances present variable extent. For convenience, with reference its conspicuous biochemical activity, we provisionally applied name “calciferol” distillation. realised, however, could be properly definitely applied, as being pure vitamin, might differ some extent from then described. Among other indications direction fact biological activity not greatly excess many samples crude product. It indeed mixture contain more than active ( cp . Bills al. , 1931). Since publication, progress has been rapid laboratory. A few weeks later Windaus (1931) gave, at discussion meeting Royal Society, preliminary description he had separated after partial condensation mixed maleic or citraconic anhydride (Diels’ reaction). Its melting-point, absorption practically identical those our product, but optical dextrorotation so much lower identical.