Physico-chemical Properties and Biological Activities of Thyme (Thymus vulgaris L.) Seed and Leaf Oil Extracts

Abstract

Background: Thyme (Thymus vulgaris L., Lamiaceae), a medicinal plant with several therapeutic properties. This plant, native to Mediterranean regions, is commonly used as a culinary herb and with a long history of use for various medicinal purposes. Objective: The present study was aimed to examine the physicochemical properties, biological activities including antioxidant and antimicrobial activities of oil extracted from seeds and leaves of common thyme grown in Eastern Ethiopia. Methods: The oil extraction was done using petroleum ether as a solvent. Then, oil quality assessment was done based on the determination of oil content, specific gravity, acid value, percent free fatty acid, peroxide value, ascorbic acid, and free radical scavenging activity using DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydrogen peroxide. The Biological activity was investigated based on antioxidant and antimicrobial activities. The antimicrobial activity was tested using disc diffusion and broth dilution methods. Results: The result of physicochemical properties of T. vulgaris seed oils demonstrated significantly higher oil content (14.75%), specific gravity (0.70±0.50), and peroxide value (1.90±0.14). The antioxidant activities of leaf oil extract presented significantly higher DPPH (22.30±1.27%). The stronger antibacterial activity with maximum zone of inhibition (15.67mm), minimum inhibitory concentration MIC (0.09µg/ml) and minimum bactericidal concentration MBC (0.18µg/ml) were was recorded for leaf oil against S. aureus. The strongest antifungal activity with maximum zone of inhibition (15.33±0.50mm) MIC (0.06 µg/ml), and minimum fungicidal concentration MFC (0.125 µg/ml) against A. niger. Conclusion: The result indicates that leaf oil has stronger antioxidant and antimicrobial potential than seed oil extract.