Effects of Cuts and Different Phenological Stages on Antibacterial and Antioxidant Activities and Chemical Attributes of Garden Thyme (Thymus vulgaris L.) Essential Oil

Abstract

Garden thyme is an aromatic plant with various applications in the pharmaceutical, food, and hygienic-cosmetic industries around the world. In this research, field-cultivated plants were harvested in two cuts and three consecutive stages (pre-flowering, flowering, and post-flowering). The essential oil percentage and compositions were identified in the essential oil samples. The antibacterial activity of the essential oil was measured against Escherichia coli and Staphylococcus aureus. The antioxidant activity, total phenol and flavonoid contents, chain-breaking activity, and IC50 were recorded. The highest essential oil percentage (2.56%) was obtained from the pre-flowering stage. The results of GC/MS revealed that p-cymene, γ-terpinene, thymol, and carvacrol were the most important constituents of the studied essential oil. The lowest antibacterial activity was recorded by the second cut at the pre-flowering stage. The highest antibacterial activity against E. coli and S. aureus were recorded by the second cut during the flowering stage and the first cut during the flowering stage, respectively. The lowest MIC was 15.75 μg mL-1 related to the second cut during the flowering stage. The plants had the highest total phenol (16.64 mg GAE g-1 DM) and total flavonoid contents (2.88 mg QE g-1 DM) at the pre-flowering stage. The highest antioxidant activity (IC50 = 134.05 μg mL-1) was observed at the pre-flowering stage. It can be said that phenological stages and cuts can affect essential oil antibacterial and antioxidant activities, as well as its chemical characteristics.