Secondary metabolites during ontogenetic phase of reproductive structures in Hypericum maculatum

Abstract

The distribution patterns of flavonoids hyperoside, isoquercitrin, quercitrin, quercetin, I3,II8-biapigenin and naphtodianthrones hypericin and pseudohypericin were studied in reproductive structures during ontogenetic phase of flowering in Hypericum maculatum Crantz. Considerable differences in the content of these secondary metabolites, in the particular flower parts were found. The content of all the metabolites studied is stable during the whole period of flowering in green flower parts (sepals). In petals, stamens and pistils their content undergoes considerable change associated with the biological functions of particular metabolites. The most conspicuous changes during ontogenetic phase of flowering were the decrease of hyperoside and isoquercitrin content in petals (average content in buds 1.589 mg g⁻¹ dry weight, average content in overblown flowers 0.891 mg g⁻¹ dry weight), the decrease of the I3,II8-biapigenin content in stamens (in buds 1.189 mg g⁻¹ dry weight, in overblown flowers 0.319 mg g⁻¹ dry weight), and the increase of hypericin and pseudohypericin content in both petals (total average content of hypericins in the buds 0.547 mg g⁻¹ dry weight; in overblown flowers 0.792 mg g⁻¹ dry weight) and stamens (in buds 0.189 mg g⁻¹ dry weight; in overblown flowers 0.431 mg g⁻¹ dry weight). Hypericins are absent in the pistil. The flavonoids hyperoside and isoquercitrin, the content of which decreased during ontogenetic phase of flowering, reach the highest contents in the pistil.