Species- and Age-Dependent Prenyllipid Accumulation in Hypericum Species' Leaves

Carotenoid, chlorophyll and tocochromanol biosynthesis and accumulation are interrelated and age-dependent in plants. Model plants produce tocopherols, but do not produce significant amounts of tocotrienols; consequently, the regulation of tocotrienol biosynthesis in plants has been scarcely studied. The Hypericum genus produces a variety of prenyllipids naturally in all parts of the plant, allowing for a glimpse into the relationship between them without genetic or other interference. Consequently, five Hypericum species' leaves of different ages were investigated-H. androsaemum, H. pseudohenryi, H. hookerianum, H. patulum and one hybrid H. × inodorum (H. androsaemum × H. hircinum). The leaves contained predominantly α-tocopherol, γ-tocotrienol and δ-tocotrienol (30.9-212.8, 8.13-22.43 and 1.87-20.8 mg 100 g^-1, respectively). Higher quantities of tocochromanols, a lower chlorophyll content and a higher a/b ratio were observed in the bottom (older) leaves. The predominant carotenoids were lutein (semi-quantitative) and β-carotene (7.60-28.63 and 2.33-12.43 mg 100 g^-1, respectively). Carotenoid contents were lower in bottom leaves than in middle or top leaves, and the highest carotenoid content was observed in H. hookerianum and H. patulum. Leaf tocopherol, tocotrienol, chlorophyll and carotenoid accumulation were section and leaf age-dependent, and distinct relationships can be observed between the accumulation of some prenyl lipids, but not others.