Oregano: A Source for Peroxisome Proliferator-Activated Receptor γ Antagonists

Peroxisome proliferator-activated receptors (PPARs) are drug targets for several perturbations of metabolic syndrome, defined as the coexistence of obesity, hyperglycemia, hypertension, and hyper/dyslipidemia. In this study, PPAR activation by oregano (e.g., Origanum vulgare) and its components was tested. Oregano extracts bind but do not transactivate PPAR gamma, and binding affinity differs among different oregano extracts. The extracts contain PPAR gamma antagonists (e.g., quercetin, luteolin, rosmarinic acid, and diosmetin), selective PPAR gamma modulators (e.g., naringenin and apigenin), and PPAR gamma agonists (e.g., biochanin A). Oregano extract and isolated compounds in the extract antagonize rosiglitazone-mediated DRIP205/TRAP220 recruitment to PPAR gamma, pointing to oregano extracts as putative food supplements for weight reduction. Rosmarinic acid and biochanin A, PPAR alpha agonists, may ameliorate the lipid profile. By enclothelial nitric oxide synthase activation, oregano extract could prevent atherosclerosis. The results warrant further investigation of oregano extract for its potential to prevent and ameliorate metabolic syndrome and its complications.