Chemical compositions, total phenolic contents, antimicrobial and antioxidant activities of the extract and essential oil of Thymbra spicata L. growing wild in Turkey

Abstract

In the study, chemical composition, total phenolic contents, antioxidant capacity and antimicrobial activities of the extract and essential oil of Thymbra spicata L. growing wild in Turkey were investigated. Chemical compositions of T. spicata L. extract and essential oil were determined using the GC–MS method. The main components of the plant extract were carvacrol (88.75%) and acetic acid (11.25%) while the main components of the plant essential oil were carvacrol (56.03%), trans caryophyllene (10.41%), p-cymene (9.61%) and γ-terpinene (6.87%). The total phenolic contents of extract and essential oil were 1350 and 3440 µg GAE g−1, respectively. Antioxidant activities of the samples were tested using DPPH and ABTS+ radical scavenging activities. The antioxidant capacity of the extract and essential oil (50.51–98.28%) is highly correlated with their phenolic contents. The antimicrobial effects of this plant were tested by disc diffusion and broth dilution methods against seven bacteria. The highest inhibition zone values were observed against Staphylococcus aureus as 15 ± 7 mm and 50 ± 10 mm, for extract and essential oil of T. spicata L., respectively. According to broth dilution method, Bacillus subtilis and Listeria monocytogenes were found to be the most resistant bacteria to the T. spicata L. essential oil (0.625%). The oil sample showed high bactericidal effect against all test microorganisms (0.313–1.25%). Essential oil of the plant exhibited higher antimicrobial activity than the extract. As a result, T. spicata L. could be used in pharmaceutical and food industries as a natural antioxidant and in antimicrobial products.