Tocopherol and tocotrienol profile in wild St. John’s wort populations in Latvia: impact of the plant’s aerial parts

St. John’s wort, scientifically known as Hypericum perforatum L., is a medicinal plant with a wide range of secondary metabolites with bioactive properties; however, it has poorly studied lipophilic phytochemicals. Two primary tocochromanols - α-tocopherol (α-T) and δ-tocotrienol (δ-T3) were identified in the aerial parts of wild St. John’s wort in Latvia. In the stems and leaves, α-T dominated (62–81%), while δ-T3 - in the flower buds, flowers, dead petals, and immature seed pods (36–70%). The flower buds had the highest content of tocotrienols (42.17–69.65 mg/100 g dw), of which δ-T3 accounted for 36% and α-T3 - for 18% of the total identified tocochromanols. The unripe seed pods exhibited the highest concentration of δ-T3 among all samples tested (38.2–52.7 mg/100 dw). St. John’s wort can be considered a natural source of δ-T3 in regions with temperate climates based on the findings of this study.