One of a group of physiologically active compounds derived from arachidonic acid, a 20-carbon fatty acid that occurs in glandular organs and the liver. It was named after the prostate gland, where it was originally found. Research on prostaglandins has been intense in recent years in view of their importance in various reproduction mechanisms and effects on blood pressure. They are believed to have significant relationships to a number of hormones; they also affect the nervous system, inhibit production of gastric juice, stimulate smooth muscles, and induce labor. They occur naturally in body tissues and biological fluids (especially semen). Both the chemical structure and metabolic functions of these compounds have been established with considerable accuracy, and several types have been synthesized; one pathway uses norbornadiene as a starting point followed by a ten-step sequence of conversions to a diol that serves as a precursor; another starts with cyclopentadiene, followed by hydroboration, yielding two intermediates from which prostaglandin can be derived. The most prolific source of prostanglandin intermediates (called syntons) is a marine organism called a gorgonian sea whip, which occurs in great numbers in coral reefs, especially in the Caribbean area. Harvesting of these has made the production of prostaglandins much less expensive. The occurrence of prostaglandin A1 in yellow onions has been confirmed. Important derivatives of prostaglandins are prostacyclins and thromboxanes; a closely related group of compounds derived directly from arachidonic acid are the leukotrienes, which occur in white blood cells.
