Comparative Effects of Origanum onites L. Extract and Carvacrol on the Metabolic Syndrome and Hepatic/Pancreatic Inflammatory Markers in Rats

This study investigated the effects of an Origanum onites L. extract, carvacrol, and metformin on the metabolic syndrome (MetS) induced by a high-fat, high-fructose diet (HFFD) in rats.Oregano was extracted using supercritical CO₂, and profiles of phenolics and volatile organic compounds were analyzed via high-performance liquid chromatography and gas chromatography-mass spectrometry methods, respectively.Rats with MetS were treated with carvacrol (MetS +CRV group), the oregano extract (MetS+OREG group), and metformin (MetS+METF group).In the two remaining groups, rats were fed only HFFD (MetS group) and a standard diet (control group).Treatments were administered daily during the final 4 weeks of a 10-week MetS induction period.Evaluations included body weight, blood pressure, blood glucose, serum lipid profile and liver function parameters, selenoprotein P (SeP), TNF-α, and histopathology of the liver and pancreas.The Lee index was significantly higher in the METS group (0.30) than in the control group (0.27), indicating greater metabolic disturbance.Liver SeP level increased in the MetS group (227.1 ng/mL) vs. control (144.3 ng/mL).The oregano extract and carvacrol did not significantly affect SeP levels.However, they both reduced systolic blood pressure and improved blood glucose level in the oral glucose tolerance test.Serum aspartate aminotransferase (AST ) and alanine aminotransferase (ALT ) levels were elevated in the MetS group but decreased with the oregano extract and carvacrol treatment.Histopathology showed that the MetS+CRV group had hepatocyte architecture resembling the control, with slight sinusoidal dilation and minimal necrosis.The MetS+OREG group also showed reduced degeneration.Overall, the oregano extract and carvacrol improved metabolic parameters and hepatic function.Further research is needed, however, to elucidate their long-term impact on selenium metabolism and tissue-specific SeP regulation in MetS.