Tocopherol and Tocotrienol Content in the Leaves of the Genus <i>Hypericum</i>: Impact of Species and Drying Technique

Abstract

α-Tocopherol (α-T) predominates in photosynthetic tissues, while tocotrienols (T3s) are reported very rarely. The genus Hypericum stands out as one of the few exceptions. Given the potential health benefits associated with tocotrienols, sourcing them from natural origins is of interest. The proper selection of plant material and the drying conditions are crucial steps in this process. Therefore, in the present study, we investigated the effects of four different drying techniques (freeze-drying, microwave–vacuum-, infrared oven and air-drying) on the tocochromanol content in leaves of three Hypericum species: H. androsaemum, H. pseudohenryi, and H. hookerianum and one hybrid H. × inodorum. The total tocochromanol content in the freeze-dried leaves harvested in September was 68.1–150.6 mg/100 g dry weight. α-T constituted 66.7–85.9% (w/w), while tocotrienols constituted 13–32% (w/w). H. pseudohenryi was characterized by the lowest tocotrienol content, while H. androsaemum and H. hookerianum had the highest, with δ-T3 and γ-T3, respectively, being predominant. Tocotrienols were more stable during drying than α-T. The greatest decrease in α-T content was observed during air-drying in the presence of sunlight, with a 27% difference compared to the absence of sunlight. The species and harvest time are factors that more strongly affect the tocotrienol content in the Hypericum leaves than the selected drying method.

Keywords

• St. John’s wort (<i>Hypericum perforatum</i> L.)
• photosynthetic
• herb
• ornamental plant
• lipophilic bioactive compound
• vitamin E