Effects of drying on antioxidant activity, essential oil content, and chemical compositions of Thymus kotschyanus: a phytochemical and in silico analysis

Thymus kotschyanus, a native species of Iran, has been used to produce essential oil having several pharmacological activities. To evaluate how different drying techniques influence essential oil quality, antioxidant activity, and the chemical composition of T. kotschyanus, we employed several drying methods including shade drying, oven drying, microwave drying, and freeze-drying. The highest yield of essential oil (1.79 ± 0.07% v/w) was obtained in an oven drying (50°C for 15 h). Additionally, thymol and carvacrol, two important phenolic compounds that make up the essential oil, were found to be at the highest concentration in oven drying (70°C for 15 h), accounting for 94.3 ± 4.6% of the total essential oil. The study also found that drying methods affected antioxidant activity, with the maximum antioxidant activity in terms of half maximal inhibitory concentration (IC50) 134 ± 1.49 µg/mL observed in the oven-drying method at 70°C for 15 h. The in silico pharmacokinetics analysis of thymol and carvacrol demonstrated no drug-likeness violation(s) and suitable oral bioavailability scores. Results of Prediction of Molecular Toxicity (eMolTox) and Prediction of Toxicity of chemicals (ProTox) 3.0 predictors were indicative of safe profile for thymol and carvacrol inside the human body without serious toxicities and off-target bindings. Although wet-lab experiments are yet to be performed to support such claims, obtained results may provide a structural basis for further development of safe phytochemicals.