A new acylated flavone glycoside with antioxidant and radical scavenging activities from Teucrium polium leaves.

The antioxidant properties of six flavones from Teucrium polium L., one of them isolated for the first time, have been established through the determination of their abilities to inhibit free radicals using DPPH, ABTS radicals and ORAC test. The structure of the new metabolite has been elucidated by 1-D (1H, 13C and DEPT) and 2-D (COSY, TOCSY, HSQC, CIGAR) NMR experiments and by ESI Q-TOF HRMS analysis. Flavones 1-3 presented an efficacious activity towards the stable DPPH radical. Analogously, compounds 2 and 3 resulted significantly active also versus ABTS cation radical. On the basis of the comparable bioactivity of luteolin-based compounds, the presence of an ortho-dihydroxy substitution in the flavone B-ring is supposed to be the structural feature responsible for the antioxidant activity.