STUDIES ON PLANTS OF CENTRAL ITALY AREA: SIDERITIS ROMANA L. SUBSP. ROMANA.

Sideritis species are famous in Balkan region and Turkey, since infusions of the aerial parts are used as tonics, carminatives, diuretics and digestives, for this reason these plants are known as ‘mountain tea’. In this work we report the content of the polar fraction of Sideritis romana L. subsp. romana, a species widely distributed on the Italian territory on garigues and dry meadows till 1900 m a.s.l. The study of the ethanolic extract of the fresh aerial parts of S. Romana subsp. romana led to the isolation and identification of seven compounds namely phytol (1), apigenin 7-O-(6''-O-acetyl-β-D-glucopyranoside) (2), 7-[[2-O-(6-O-acetyl-β-D-allopyranosyl)-β-D-glucopyranosyl]oxy]-5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)- 4H-1-benzopyran-4-one (3), 7-[[2-O-(6-O-acetyl-β-D-glucopyranosyl)-β-D-glucopyranosyl]oxy]-2-(3,4-dihydroxyphenyl)-5-hydroxy-4H-1-benzopyran-4-one, (4), 7-[[2-O-(6-O-acetyl-β-D-allopyranosyl)-β-D-glucopyranosyl]oxy]-5-hydroxy-2-(4-hydroxyphenyl)- 4H-1-benzopyran-4-one (5), 6-deoxiharpagide (6) and harpagide (7). Compound (1) is a very common acyclic diterpene alcohol, compounds from (2) to (5) are glycosidic-flavones derivates of apigenin and luteolin and lastly compounds (6) and (7) are iridoids. Iridoids are considered chemotaxonomic markers in Lamiaceae, in particular harpagide and its derivatives, and were evidenced for the first time in this study as constituents of S. romana subsp. romana. The second important aspect is the presence of acetylated apigenin and luteolin glycosides containing allose. This is the first report on the occurrence of these kinds of flavones in the genus Sideritis, while they have been previously isolated only from species comprised in Ajugoideae subfamily (Ajuga reptans, A. genevensis) as glycosides as well as free aglycones. In this context is worth to note the absence of isoscutellarein derivatives, which had been already evidenced in the genus Sideritis and are considered chemosystematic markers since their occurrence seems to be restricted to some correlated genera in the Lamiaceae as Pogostemon, Galeopsis and Stachys. The presence of a considerable amount of flavonoids might perhaps justify the traditional use of this species as a herbal tea. In fact apigenin and luteolin glycosides resulted to exert a strong anxiolytic action.