Investigation of essential oil composition, hypericin content, and antioxidant capacity of different extracts from flowers and leaves of Hypericum perforatum L. growing wild in Turkey

In this study, we analyzed the composition of essential oils obtained through hydrodistillation from the leaves and flowers of Hypericum perforatum L., a wild plant species found in Sile, Istanbul, located in the northwest of Turkey. We employed gas chromatography-mass spectrometry (GC-MS) to identify the constituents. Additionally, we investigated the antioxidant capacity and total phenolic composition of the plant using DPPH (2,2-diphenyl-1-picryl-hydrazyl), CUPRAC (CUPric Reducing Antioxidant Capacity), and Folin-Ciocalteu methods. Furthermore, we determined the total amount of hypericin present in the plant. The analysis of essential oils from the leaves revealed the identification of fifty-nine compounds, with 2-methyloctane (34.93%), cyclotetradecane (9.12%), limonene (7.24%), 3-methylnonane (5.58%), alpha-pinene (5.55%), n-tetradecanol (3.15%), 2-methyldecane (3.03%), nonane (3.0%), and spathulenol (2.07%) as the primary constituents. On the other hand, the essential oil from the flowers contained fifty-seven compounds, with 2-methyloctane (52.81%), alpha-pinene (4.65%), cyclotetradecane (4.04%), n-tetradecanol (2.99%), D-verbenone (2.28%), 2-methyl-2-octanol (2.17%), and caryophyllene oxide (2.0%) as the major components. When evaluating the antioxidant capacity of H. perforatum L. extracts, our results indicated that both leaves and flowers exhibited significant antioxidant capacity in DPPH assays. However, the Cu2+ ion reduction capacity was comparatively low in the CUPRAC method. The highest hypericin contents of leaves and flowers were determined in extraction with 60% ethanol/water for 120 minutes at 50 degrees C as 0.122 g/g % and with 80% ethanol/water for 120 minutes at 50 degrees C as 0.360 g/g %.