DNA-protective and antioxidant potentials of thym samples: Chemometric and bioactive profiling from Iraq's Kurdish highlands and Siirt, Türkiye

Abstract

Thyme, a fragrant herb from the Lamiaceae family, is highly valued for its essential oil content, making it a key ingredient in perfumery, aromatherapy, phytotherapy, and pharmacology. This study investigates the chemical composition and biological activity of thyme samples collected from Iraq's Kurdish Region (Qandil, Asos, Balambo, Karokh) and Siirt, Türkiye (Eruh, Şirvan, Kezer, Tillo, and other regions). Comprehensive analyses were conducted to assess micro- and macro-element levels, total phenolic and flavonoid content, and antioxidant properties using methanolic extracts. The highest phenolic and flavonoid contents were 226.83 ± 0.21 mg/mL gallic acid equivalent (GAE) and 2.59 ± 0.02 mg/mL of routine equivalents (RE). Antioxidant activity, evaluated via FRAP and DPPH assays, demonstrated IC₅₀ values of 1.32 mg/mL and 2.05 mg/mL. Maximum metal chelation was 22.92 %. LC-MS/MS identified 29 out of 37 phenolic compounds, including abundant levels of hesperidin (62.37 ± 0.02 μg/kg), rosmarinic acid (19.90 ± 0.01 μg/kg), and Ferulic acid (2.23 ± 0.01 μg/kg). Chemometric analyses, including PCA and cluster analysis, highlighted regional differences. Hydroxyl radicals (•OH) produced through the Fenton reaction involving H₂O₂ and Fe(II) cause damage to the pBR322 plasmid DNA. This damage is evidenced by a reduction in the supercoiled form and an increase in relaxed or linear DNA forms following oxidative stress. DNA damage assays demonstrated that thyme extracts provided partial protection against Fenton reaction-induced damage without compromising DNA integrity. These findings emphasize thyme's potential for pharmaceutical, nutritional, and industrial applications.