Evaluation of antioxidant activity and cytotoxic potential of thymus vulgaris leaf extracts

Abstract

Thymus vulgaris is a most important medicinal plant, it is rich in bioactive secondary metabolites. The leaves are used for the treatment of several diseases. In the present study, the antioxidant activity and cytotoxic potential of T. vulgaris leaf extracts were evaluated. Leaf extracts were prepared using cold and hot procedures with varied polarity solvents (chloroform, acetone, ethanol, and aqueous methanol [50% v/v]). The total phenol content (TPC) and antioxidant potential of the extracts were determined. The leaf extracts were fractionated using Gas Chromatography/Mass Spectroscopy (GC/MS), and the acetone extract's cytotoxic effects on breast cancer cell lines were assessed. The results indicated that the aqueous methanol extract (hot method) had the highest TPC (76.45 ± 2.88 mg/g of dry plant content of gallic acid equivalence [mgGAEg-1]), while the lowest TPC was obtained in the chloroform extract (cold method; 37.36 ± 2.45 mgGAEg-1). The maximum antioxidant activity was observed in the ethanol extract (hot method; 83.9% ± 0.96), while a minimum value was recorded for the acetone extract (hot; 66.3% ± 0.71) at a concentration of 100 μg/mL. GC/MS analysis revealed the presence of phenolic compounds such as p-Cymen-3-ol, p-Cymen-2-ol, 2,5-diethylphenol, 6-ethyl-3, 4-dimethylphenol, 7,11-dimethyldodeca-2,6,10-trien-1-ol thymol and some flavonoids. The acetone extract showed an anticancer effect on the MCF-7 and Cal-51 breast cancer cell lines, as well as the HBL-100 normal cell line. The results of this study provide scientific justification for the medicinal use of T. vulgaris leaf extracts that contained various polyphenol components; it has strong antioxidant and antitumor activity.