Isolation and structure elucidation of bioactive compounds from the roots of the Tunisian Ononis angustissima L.

A phytochemical investigation of the roots of Ononis angustissima L. (Fabaceae) offered to the bio-guided isolation of new isoflavone 3-(4-(glucopyranosyloxy)-5-hydroxy-2-methoxyphenyl)-7-hydroxy-4H-chromen-4-one 1, together with nine known compounds, ononin 2, formononetin 3, (+)-puerol A-2'-O-β-D-glucose 4, (-)-puerol B-2'-O-β-D-glucopyranose ((-)-sophoraside A) 5, (+)-puerol A 6, (-)-trifolirhizin 7, (-)-trifolirhizin-6'-O-malonate 8, (-)-maackiain 9 and (-)-medicarpin 10. Compounds 2-10 were isolated and identified for the first time in Ononis angustissima. We investigated antioxidant capacities of isolated molecules and results showed that compound 6 exhibited the highest antioxidant activity with IC50 values of 19.53 μg/mL, 28.29 μg/mL and 38.53 μg/mL by DPPH radical, ABTS radical cation and reducing power assay, respectively, and an interesting IC50 (20.45 μg/mL) of 1 against DPPH. In addition, the neuroprotective activity of six isolated molecules (4-7, 9, 10) were evaluated. Following the exposure of PC12 cells to Aβ25-35, compounds 9 and 10 triggered a significant increase of cell viability and in a dose dependent manner.