Comparative chemical and biological study of essential oils and n-hexane extracts of Thymus vulgaris and Thymus serpyllum (Lamiaceae)

This study presents a comparative chemical and biological evaluation of essential oils (EOs) and n-hexane extracts from Thymus vulgaris and Thymus serpyllum (Lamiaceae), alongside a reference commercial thyme oil. GC-MS analysis revealed significant differences in chemical composition among the samples, with T. serpyllum oil characterized by high thymol (74.47%) and caryophyllene (9.89%) content, while the commercial oil was dominated by carvacrol (80.37%). Cytotoxicity was assessed using the sulforhodamine B (SRB) assay on human skin fibroblast (HSF) cells to evaluate safety. Most samples exhibited low cytotoxicity (IC₅₀ > 100 µg/mL), except for T. serpyllum oil, which showed strong cytotoxicity (IC₅₀ = 18.48 µg/mL). Antidiabetic activity was evaluated via α-glucosidase and α-amylase inhibition assays. T. serpyllum oil demonstrated moderate α-glucosidase inhibition (IC₅₀ = 536.9 ± 1.04 µg/mL), while other samples showed weak or negligible activity. Wound healing potential was assessed using an in vitro scratch assay on HSF cells. T. serpyllum oil at 0.05 µg/mL achieved complete wound closure within 72 h, outperforming other samples, including the commercial reference. Molecular docking of its major compounds (thymol, caryophyllene, α-selinene, and 3',5'-dimethoxyacetophenone) revealed favorable binding affinities to key wound healing targets (collagenase, MMP-12, TGF-β), supporting the observed biological activity. Overall, T. serpyllum EO (TSV) exhibited superior wound healing capacity and moderate antidiabetic activity, with acceptable safety at low concentrations. These findings highlight its potential as a natural therapeutic agent and underscore the importance of standardizing thyme products for consistent pharmacological efficacy.