Impact of Soil on Biomass Yield and Accumulation of Lipophilic Secondary Metabolites in Four Hypericum Species

The genus Hypericum is a widely distributed ornamental and therapeutic herb known for its diverse bioactive compounds, including xanthones. The levels of secondary metabolites in plants are influenced by the specific plant part, agronomic conditions, and environmental factors. Recently, the occurrence of tocotrienols, rare tocochromanols, was reported in Hypericum perforatum. Therefore, this study investigated the profiles of tocochromanols in different plant sections—leaves, stems, flowers, and flower bud—of four Hypericum species: H. perforatum, H. annulatum, H. androsaemum, and H. × inodorum, cultivated in three types of soil: potting, sandy, and clay. In the initial growing year, the highest biomass yield was recorded for H. perforatum grown in potting soil. Soil and species significantly influence biomass yield (p < 0.05). The inflorescences of H. perforatum were dominated by tocotrienols (T3s), primarily α-T3 and δ-T3, an observation not noted for H. annulatum. α-Tocopherol (α-T) was dominant in the leaves, while in the stems, except for H. perforatum (α-T), tocotrienols—γ-T3 and δ-T3 in H. inodorum and H. androsaemum and α-T3 and γ-T3 in H. annulatum—were more prevalent. This study demonstrates differences in tocochromanol accumulation in different parts of the four Hypericum species grown in different soils.