Prostaglandins are derived from :
Coicosteroids
Oleic acid
Linoleic acid
Arachidonic acid
Prostaglandins are derived from arachidonic acid through the cyclooxygenase (COX) pathway.Two isoforms of COX have been recognized.COX-1 is expressed constitutively, whereas COX-2 is induced by growth factors, tumor promoters, and proinflammatory cytokines.COX catalyzes oxidative cyclization of arachidonic acid to prostaglandin endoperoxide, which is the immediate precursor of prostaglandins, thromoboxane, and prostacyclin