§ 7 THE LUTEIDIN PROBLEM 



45 



and that of the allo-pregnanediol-acctate; the values given 

 for these being, respectively, 182° C and 140° C. 



We may finally mention that the two crystalline fractions 

 did not prove to be quite ash-free (this is, indeed, a well- 

 known point of difficulty with pregnanediol-glucuronide), 

 so that the elementary analysis could not give us any precise 

 figures with regard to the constitution of the crystals. It was 

 remarkable, however, that, the H % was about 4 % too low, 

 as calculated relatively to Na-pregnanediol-glucuronide, the 

 C % lay up to as much as 1 9 % below the value expected, 

 which cannot be explained by the mere admixing of NaCl 

 and Na2S04. 



Rather does the conclusion seem to force itself upon us 

 that there must be a second substance present in the preg- 

 nanediol complex, which cannot be removed by recrystalli- 

 sation, and present in different quantities in' the two 

 crystalline fractions. This would explain not only the 

 difference in the melting points, but also the fact that the 

 highest of the two melting points is still 8 ° too low. 



A concentration-curve was determined of crystals melting 

 at high temperature. The sharp bend lay at a quantity of 380 

 7, which means that, already with this quantity, per 750 ml 

 aquarium water, the maximal growth of 5, and on one 

 occasion even 7 A.U. was obtained, whilst DUYVENE DE 

 Wit, discussing the results of the testing of pregnanediol, 

 remarks that only with the high concentration of 2000 y 

 per 750 ml water could a distinct reaction be obtained. 

 Further investigation will, therefore, be necessary for the 

 solution of the luteidin problem. 1 



^ In the Bioch. J., 40, (1946), 53, MARRIAN and GOUGH stated that 

 they had isolated pregnane 3 (a)-ol-20-one from the products of hydro- 

 lysis of "sodium pregnanediol glucuronidate", a water-soluble derivative 

 which was persistenly present in the latter as a 20 % impurity, and could 

 not be removed by further 'purification'. This impurity may perhaps be 

 identical with our "luteidin". 



