The new cyclic polyketide 7,9,11-trihydroxytetracos-2-eneoic acid δ-lactone (1), together with other eleven known compounds, were isolated from Ononis spinosa, growing wildly in Jordan. All isolated compounds were identified by thorough investigation of their spectral data including NMR and HRESIMS. Antioxidant activity testing of puerol B, specionin and the new cyclic polyketide revealed that puerol B had the highest DPPH radical scavenging activity (IC50 0.09 ± 0.006 mg/ml) as compared to α-tocopherol (IC50 0.039 ± 0.0006 mg/ml), while specionin had the highest ABTS radical scavenging power (IC50 0.013 ± 0.0008 mg/ml) as compared to α-tocopherol and ascorbic acid (IC50 0.042 ± 0.0004; 0.026 ± 0 .0007 mg/ml; respectively).
Keywords: 7,9,11-trihydroxytetracos-2-enoic acid δ-lactone; Leguminoseae; Ononis spinosa; cyclic polyketides; isoflvonoids.