prostaglandin e2 and prostaglandin f2 alpha , two prostanoids that can be formed either enzymatically or nonenzymatically from prostaglandin h2 , accounted for greater than 75 % of isolatable 20-carbon fatty acid cyclooxygenase products synthesized from endogenous and exogenous arachidonic acid .
C0012472
prostaglandin e2
C0033554
prostanoids