External and vacuolar flavonoids from ibero-North African Sideritis species. A chemosystematic approach

The flavonoids, both external aglycones and vacuolar flavonoid glycosides, have been identified in the aerial parts of endemic North African Sideritis species. The flavonoids produced by these African species are very similar to those produced by Spanish species, being mainly 7-allosylglucosides of 8-hydroxyflavones. Two new flavonoid glycosides, apigenin and luteolin 7-allosylglucosides, have been identified in these plants. Species of the section Sideritis are characterized by the accumulation of the 7-glycosides of 8-hydroxyflavones (isoscutellarein, hypolaetin and their methyl ethers) whereas those of section Hesiodia accumulate 7-glycosides of the common flavones (apigenin, luteolin and chrysoeriol).