Animal prostaglandins and plant jasmonates are well-known enzymatically for
med cyclopentanoic lipids that have regulatory functions and serve as induc
ible mediators of host defense reactions. A novel group of prostaglandin-li
ke compounds, the isoprostanes, generated in animals and plants by a nonenz
ymatic, free radical-catalyzed process, are now suspected to be mediators o
f oxidant injury in vivo.