Antioxidant Potential of Thymus willdenowii Boiss & Reut. Aqueous Extract and Effect of its Supplementation on Hyperlipidemia and Paraoxonase-1 Arylesterase Activity in High-Fat Diet-Fed Rats

Thymus willdenowii Boiss & Reut. (T. willdenowii) is a medicinal plant that grows in the Moroccan High Atlas Mountains. It is used in local folk medicine to treat several disorders including cardiovascular disease. In this study, we aimed to evaluate the antioxidant and anti-hyperlipidemic effects of the traditionally used aqueous extract of T. willdenowii. The extraction of the plant was assessed using the traditionally used decoction method. Total contents of polyphenols (TPC), flavonoids (TFC), and tannins (TTC) were estimated and in vitro antioxidant assays namely DPPH, FRAP, and TAC were carried out to evaluate its antioxidant potential. Moreover, the anti-hyperlipidemic activity was tested on rats fed a high-fat diet (HFD) containing sucrose (15%), lard (15%), and cholesterol (2%). Thyme extract was given daily at 500 mg/kg. After 2 months of treatment, lipid profile parameters and arylesterase activity were determined. The findings showed that T. willdenowii extract is rich in phenolic compounds (TPC = 127.34 GAE mg/gE; TFC = 105.43 RE mg/gE; TTC = 24.08 CE mg/gE) and exhibits important antioxidant activity (DPPH IC50 = 0.41 mg/mL; FRAP value = 1.31 Fe2+E mM; TAC value = 322.13 AAE µg/gE). Moreover, T. willdenowii extract significantly reduced the alterations caused by HFD intake by decreasing blood lipids (TC: -28.19 %; TGs: -22.82 %; LDL-C: -35.11 %) and increasing paraoxonase-1 arylesterase activity (+12.83 %). We conclude that the traditional use of T. willdenowii is effective in the treatment of hyperlipidemia.