Determination of essential oil and chemical composition of St. John’s Wort

Considering it contains a variety of physiologically active compounds, including flavonoids, common phenols, and essential oils (EOs), St. John’s wort (Hypericum perforatum L.) is a common plant in Bulgaria that is predominantly used in folk medicine to cure various disorders. Determining the chemical makeup of St. John’s wort inflorescences that were gathered from northern Bulgaria was the purpose of this investigation. The antioxidant activity of H. perforatum L. extracts was assessed using 1,1-diphenyl-2-picrilhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and Trolox equivalent antioxidant capacity (TEAC) tests on methanol extract. The amount of EO obtained by water distillation was 0.08%, with its main components (over 3%) being n-nonane (27.46%), β-sesquiphellandrene (11.17%), heptanal dimethyl acetal (5.94%), ethyl hexyl ketone (5.93%), undecane (3.75%), sabinene (3.3%), and tridecyl alcohol (3.1%). Methanol extracts were obtained from the inflorescences, with the total flavonoid content determined as 8.66 mg quercetin equivalents (QE)/mg and total phenolic content as 271.33 mg Gallic acid equivalent/g. The FRAP assay yielded 493.07 µmol/L of antioxidant activity, while the TEAC assay yielded 106.39 µmol/L, respectively. Our findings enable a comprehensive characterization of H. perforatum from Bulgaria and an assessment of its oil suitability for potential industrial applications. Additionally, the results could guide the selection of specimens for future targeted breeding efforts.