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 <i>Hypericum</i> 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 <i>Hypericum</i> species' leaves of different ages were investigated-<i>H. androsaemum</i>, <i>H. pseudohenryi</i>, <i>H. hookerianum</i>, <i>H. patulum</i> and one hybrid <i>H.</i> × <i>inodorum</i> (<i>H. androsaemum</i> × <i>H. hircinum</i>). 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 <i>a</i>/<i>b</i> 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 <i>H. hookerianum</i> and <i>H. patulum</i>. 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.