Ludwig Fraenkel: 'spiritus rector' of the early progesterone research

The search for the corpus luteum hormone progesterone took more than three decades and the efforts of many scientists all over Europe and the USA. In 1934, after a dramatic neck-and-neck scientific race, four research groups independently from each other reported on the successful isolation of the p ure substance. Two of the groups were from the then-German cities of Bresla u and Danzig, the others were from the USA and Switzerland. Possibly, the B reslau group had already had the purified hormone as early as 1933. Ar that time, gynecologist Ludwig Fraenkel (1870-1951) had been their 'spiritus re ctor' for more than three decades. It was Fraenkel himself who at the begin ning of the century, in examining a hypothesis of the anatomist Gustav Jaco b Born (1851-1900), had provided experimental proof for an endocrine functi on of the corpus luteum. Later on, Fraenkel enlisted the help of chemist Ka rl Heinrich Slotta (1895-1987) in the purification of the hormone. This too k place after important requirements for the isolation and for the semiquan titative determination of the hormone (e.g. Corner-Alien test) had been est ablished elsewhere. Also belonging to the Breslau research group were Erich Fels (1897-1981) and Heinrich Ruschig (born in 1906). Fels was an assistan t to Fraenkel, Ruschig a PhD candidate directed by Slotta. Shortly after th e group had succeeded in purifying progesterone, the Breslau group was brok en apart by the National Socialist's racial policies: Fraenkel, Fels and Sl otta were forced into emigration. (C) 1999 Elsevier Science Ireland Ltd. Al l rights reserved.