Flavonoid distribution during the development of leaves, flowers, stems, and roots of Rosmarinus officinalis.: Postulation of a biosynthetic

The distribution of seven flavonoids, eriocitrin, luteolin 3'-O-beta-D-glucuronide, hesperidin, diosmin, isoscutellarein 7-O-glucoside, hispidulin 7-O-glucoside, and genkwanin, has been studied in Rosmarinus officinalis leaves, flowers, stems, and roots during plant growth. The maximum level reached by luteolin 3'-O-beta-D-glucuronide in leaves during June-August suggests the existence of a delay between the activation of the enzymes involved in the flavanone and flavone biosynthesis. The presence of hesperidin and diosmin in the vascular system is significant, and hesperidin shows even higher levels than the phenolic diterpenes and rosmarinic acid. The distribution of flavonoids observed in R. officinalis suggests a functional and structural relationship between phytoregulators and flavonoids, where flavonoids would be protectors of the activity of phytoregulators. A hypothesis for the general pathway of biosynthesis of these compounds in plants of the family Labiatae is proposed.