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Carl Djerassi

(b. 1923)

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(1923–) American chemist

Djerassi was born in the Austrian capital of Vienna, the son of a Bulgarian physician and an Austrian mother. As both parents were Jewish, Djerassi emigrated to America in 1939. He was educated at Kenyon College, Ohio, and at the University of Wisconsin, where he completed his PhD in 1945, the same year in which he became an American citizen. From 1945 to 1949 he worked for the pharmaceutical company CIBA in Summit, New Jersey, as a research chemist. In 1949 Djerassi decided to join a new pharmaceutical company, Syntex, in Mexico City, to work on the extraction of cortisone from plants. At that time it was being produced from cattle bile at a cost of 200 dollars a gram.

Despite competition from other leading laboratories, Syntex were the first to extract cortisone (C2 1H2 8O5) from a vegetable source, namely diosgenin (C2 7H4 2O3), a steroid derived from a variety of wild Mexican yam.

Following their initial success Djerassi and his team turned their attention to the steroid hormone progesterone. Known as ‘nature's contraceptive’, the hormone inhibits ovulation. Why, then, could it not be taken as a simple, natural contraceptive? The difficulty was that taken orally it lost most of its activity. Further, as hormones were extracted from such animal sources as human urine, bull's testicles, and sow's ovaries where they occur in small amounts, they tended to be very expensive. The first step was to produce progesterone synthetically. This was achieved at Syntex by Djerassi and others in the early 1950s, the price of progesterone dropped dramatically and it became available in large quantities.

Chemists were inhibited by the belief that steroid hormones were structure-specific; change the structure, the claim went, and the potency is lost. Djerassi was aware, however, that Max Ehrenstein had destroyed this myth a decade earlier and that it was at least conceivable that progesterone could be changed into an oral form without necessarily changing its potency.

Progesterone (C2 1H3 0O2) contains four rings of carbon atoms. Following some hints in the literature Djerassi thought that the removal of the methyl group at position 19, thus forming 19-norprogesterone, would increase its potency. His hunch proved to be sound. He was also aware that an acetylene bond introduced into position 17 of the male hormone testosterone increased its oral activity, although known as ‘ethisterone’, it had found no use.

Djerassi's crucial step was to propose that ethisterone's potency could be enhanced, as with progesterone, by removing a methyl group. By October 1951 he had produced testosterone minus a methyl group, but with an added acetylene group. The precise result was 19-nor-17a-ethinyltestosterone, which proved to be a highly active oral progestational hormone. A patent was filed in November 1951. After the appropriate testing it received Federal approval in 1962 under the name Ortho-Novum. Djerassi received one dollar for the patent, a standard payment by a pharmaceutical company to its staff.

In 1951 Djerassi left Syntex for Wayne State University, Detroit, where he remained until 1959 when he was appointed professor of chemistry at Stanford. He continued to work for Syntex, as vice-president in charge of research (1957–69) and as president of research from (1969–72).


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