The effect of α-terpineol enantiomers on biomarkers of rats fed a high-fat diet

Alpha-terpineol is a monoterpenoid found in many essential oils, being widely used in food and household products. In vitro antioxidant and anti-inflammatory activities have already been associated with this alcohol; therefore, this study aimed to check if these properties were also present in vivo, counteracting the oxidant and inflammatory effects of a high-fat diet, as well as if there were differences in the biological activities among the two α-terpineol enantiomers. Thus, this work evaluated the effect of supplementation of α-terpineol enantiomers (at 25, 50 and 100 mg/kg of diet) on biological parameters of diet-induced obese Sprague-Dawley rats. In general, α-terpineol improved the nutritional parameters of rats fed a high-fat diet. The intake of α-terpineol at concentrations ≥50 mg/kg was able to reestablish the insulin sensibility and reduced (p < 0.05) serum levels of pro-inflammatory cytokines TNF-α and IL-1β, when compared with the control group. The intake of R-(+)- and (–)-α-terpineol decreased the TNF-α level by approximately 1.5 and 3.4 times, respectively, when compared with the high-fat group, regardless of the concentration. Moreover, both enantiomers at 50 mg/kg decreased the levels of serum thiobarbituric acid reactive substances (TBARS) by 2.6–4.2 times, while hepatic TBARS were reduced in approximately 1.6 times, regardless of the compound and concentration tested. Further experiments are suggested to confirm the mechanisms and the security of α-terpineol in different experimental models and more extended exposure experiments.