16-Ketoestradiol

16-Ketoestradiol (also known as 16-KE2) is a metabolite of estradiol, which is one of the three main estrogens produced in the human body. It is formed in the liver through the process of hydroxylation, a chemical reaction that introduces a hydroxyl group into an organic compound.

Structure and Synthesis

16-Ketoestradiol is a steroid hormone, meaning it is derived from cholesterol. It has a similar structure to estradiol, but with an additional keto group at the 16th carbon position. This modification is carried out by the enzyme cytochrome P450, specifically the isoform CYP1B1.

The synthesis of 16-ketoestradiol begins with the conversion of cholesterol to pregnenolone by the enzyme cholesterol side-chain cleavage enzyme. Pregnenolone is then converted to progesterone, which is further metabolized to estradiol. Finally, estradiol is hydroxylated at the 16th carbon position to form 16-ketoestradiol.

Function

16-Ketoestradiol is believed to have weaker estrogenic activity than estradiol. However, its exact role in the body is not fully understood. Some studies suggest that it may have anti-inflammatory properties and could play a role in the prevention of cardiovascular disease.

Clinical Significance

Abnormal levels of 16-ketoestradiol may be associated with certain health conditions. For example, elevated levels have been observed in women with polycystic ovary syndrome (PCOS), a hormonal disorder that can cause irregular menstrual periods and infertility. Further research is needed to fully understand the clinical significance of 16-ketoestradiol.

See Also

• Estradiol
• Estrogen
• Steroid hormone
• Cytochrome P450
• Polycystic ovary syndrome