Secondary metabolites from the aerial parts of Sideritis germanicopolitana and their in vitro enzyme inhibitory activities
Three iridoid glycosides, 5-allosyloxy-aucubine (1), melittoside (2), ajugol (3), five phenylethanoid glycosides, verbascoside (4), martynoside (5), leucoseptoside A (6), lamalboside (7), decaffeoylverbascoside (8), four flavonoids, xanthomicrol (9), isoscutellarein 7-O-[6'''-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (10), 4'-O-methylisoscutellarein 7-O-[6'''-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (11), 3'-hydroxy-4'-O-methylisoscutellarein 7-O-[6'''-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (12), and two lignan glycosides dehydrodiconiferylalcohol 4-O-β-D-glucopyranose (13) and pinoresinol 4'-O-β-glucopyranoside (14) were isolated from the aerial parts of Sideritis germanicopolitana. Their structures were determined on the basis of detailed NMR and HRESIMS analyses. To our knowledge, all compounds are being reported for the first time from S. germanicopolitana, while the isolated lignans (13 and 14) are new for the genus Sideritis. In vitro evaluation of AChE, BChE and LOX inhibitory effects of all the tested compounds (1–14) resulted in low to moderate activities.