[Endogenous ligands for PPARs].

Peroxisome proliferator-activated receptors (PPARs), a family of three nuclear receptors/transcription factors, are widely recognized as molecular targets for drugs against lifestyle related disease. In spite of intensive search for natural ligands, no truly endogenous ligand has been identified as yet. Rather, these results have lead to the suggestion that PPAR may act as various lipid sensors. Namely, the ligand binding modes of PPARs would be similar to those of odorant receptors or substrate-binding modes of drug-metabolizing enzyme P450 family. In this brief review, free fatty acids, lipid mediators in arachidonate cascade and polyphenolic compounds such as resveratrol will be discussed as natural ligands for PPARs.