Steroidal aromatase inhibitors

Steroidal aromatase inhibitors are a class of drugs that are mostly used for treating breast cancer in postmenopausal women. High levels of estrogen in breast tissue increases the risk of developing breast cancer and the enzyme aromatase is considered to be a good therapeutic target when treating breast cancer due to it being involved in the final step of estrogen biosynthetic pathway and also its inhibitation will not affect production of other steroids. Aromatase Inhibitors are classified into two categories based on their structure, nonsteroidal and steroidal; the latter resemble the structure of androstenedione. Steroidal aromatase inhibitors irreversibly inhibit the enzyme by binding covalently to the binding site of aromatase so the substrate can't access it.

In 1944 the Worcester Foundation for Experimental Biology (WFEB) was established. The foundation was the center point of collaboration of many scientists interested in reproduction, neurophysiology and steroid biochemistry. One of the foundations work was the understanding of the mechanism of conversion of androgens to estrogens. The group worked on understanding the biosynthesis and metabolism of steroids that are produced by adrenal glands, testes and ovaries. Andre Meyer later hypothesized that the aromatization of androstenedione was enzymatic and this was proven in the 1980s with the purification of aromatase. In the early 1970s the investigators agreed upon the fact that aromatization of ring A was facilitated by a cytochrome -mediated enzyme, proven with the blockade of aminoglutethimide (AG, known to block P450-mediated enzymes.

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