Hypolipidemic and antioxidant effect of polyphenol-rich extracts from Moroccan thyme varieties

Background & aims: In the present study, the polyphenol-rich extracts of four endemic medicinal plants (Thymus satureioides, Thymus zygis L., Thymus atlanticus and Thymus vulgaris) widely used in the Errachidia area (south east of Morocco) were analyzed for their hypocholesterolemic, hypotriglyceridemic, and antioxidant activities. Methods: Hyperlipidemia was induced in rats by intraperitoneal injection of Triton WR-1339 at a dose of 200 mg/kg body weight. The animals were divided into seven groups: the normolipidemic control group (NCG), the hyperlipidemic control group (HCG), the T. atlanticus-treated group (TA), the T. zygis-treated group (TZ), the T. satureioides-treated group (TS), the T. vulgaris-treated group (TV) and the Fenofibrate-treated group (FF). The hyperlipidemic groups were treated with herbal extracts at a dose of 0.2 g/100 g body weight and with fenofibrate at a dose of 6.5 mg/100 g body weight. The antioxidant activity of the polyphenol-rich extracts was assessed by using the Ferric Reducing Antioxidant Power assay (FRAP), the Radical Scavenging Activity method (RSA) and the inhibition of 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) that induces oxidative erythrocyte hemolysis. Results: After 24 h of treatment with polyphenol-rich extract from T. atlanticus, plasma total cholesterol, triglycerides and LDL-cholesterol decreased by 82.8% (P < 0.001), 96.4% (P < 0.001) and 82.2% (P < 0.001), respectively. The results demonstrate that the four aqueous thyme extracts possess antioxidant activity as evidenced by ferric reducing/antioxidant activity (equivalent to 50.79 ± 2.02 mmol Trolox/g of extract) and radical scavenging activity (IC 50: 0.44 ± 0.02 mg/mL of extract). Conclusion: Our findings suggest that polyphenol-rich thyme extracts might be considered for therapeutic use to treat atherosclerosis. © 2012 European Society for Clinical Nutrition and Metabolism.