Phytochemical study of a species with ethnopharmacological interest. Sideritis romana L.

The phytochemical analysis of Sideritis romana L., a species largely used as a traditional remedy, led to the isolation and the identification of several acetylated flavonoid glycosides with apigenin, luteolin, hypolaetin and isoscutellarein backbone. Among these, an apigenin derivative (2) was recognized for the first time in Sideritis as well as in the Lamiaceae family. The iridoidic pattern of this species showed the presence of harpagide, currently considered the main taxonomical maker in this genus, together with 6-deoxyharpagide which is a rare compound since it was previously recognized in a limited number of species of Lamiaceae. Other identified iridoids were ajugoside and bartsioside, the latter recognized for the first time in the species as well as in the family. Acetylated flavonoid glycosides and iridoid glucosides are considered of chemotaxonomic relevance in several genera comprised in the Lamioideae subfamily and the occurrence of both of these classes of compounds in S. romana was discussed. The co-presence of the acetylated apigenin derivative and of 6-deoxyharpagide could be used as a marker at a specific level seen their relative rarity in Lamiaceae. Regarding the traditional uses of this species, the isolated compounds may give a rationale from a chemical standpoint.