A new arsenal of polyphenols to make Parkinson's disease extinct: HPLC-MS/MS profiling, very interesting MAO-B inhibitory activity and antioxidant activity of Otostegia fruticosa

Fifteen compounds belong to phenolic acids, derivatives of phenolic acids, iridoids, xanthones and flavonoids were characterized in the methanolic extract of Otostegia fruticosa leaves using HPLC-MS/MS. Extract has been also investigated for its MAO-B inhibitory activity, antioxidant activity, total phenolic and total flavonoid content. The extract exhibited interesting MAO-B inhibitory activity (IC50; 2.24 ± 0.08) compared to the reference compound selegiline (0.55 ± 0.02 mg/mL). It also showed a potent antioxidant activity proven in both DPPH and ORAC assay methods. The extract showed an IC50 of 3.64 ± 1.22 mg/mL in the DPPH test which was significantly lower than that of the standard ascorbic acid which attained an IC50 of 18.3 ± 1.41 mg/mL. Moreover, in the oxygen radical absorbance capacity assay (ORAC) the extract showed a decline in the IC50 to 3.48 ± 1.16 mg/mL as compared to the standard Trolox which exhibited an IC50 of 27.0 ± 13.41.