Evaluation of Antioxidant, Anti-inflammatory, and Antinociceptive Properties of Aerial Parts of Vicia sativa and its Flavonoids

Objective: In this study, we aimed to identify the minor flavonoids of the areal parts of Vicia sativa, a biologically active plant growing in El-Hassana, North Sinai, Egypt, and to monitor the antioxidant, anti-inflammatory, and antinociceptive activities of the plant extract and its purified flavonoids. Methods: antioxiant activity of V. sativa was assessed by four different assays including DPPH assay, quenching of ROO radicals, respiratory burst in rat neutrophils, and lipid peroxidation. On the other hand, antiinflammatory and antinociceptive effects of V. sativa and its flavonoids were assessed by carrageenaninduced inflammation in mice, acetic acid-induced writhing and formalin-licking test. Results: Nine flavonoids were isolated from the ethanol extract of the aerial parts of V. sativa and identified as active components: apigenin 4'-O-β-D-glucopyranoside [1], apigenin 6,8-di-C-β-D-glucopyranoside [2], apigenin 6-C-α-L-arabinopyranoside-8-C-β-D-glucopyranoside [3], kaempferol-3-O-β-Ldirhamnopyranosyl (1→2, 1→6)- β-D-glucopyranoside [4], kaempferol 3-O-(4-β-D-xylopyranosyl)-α-L-rhamnopyranoside-7-O-L-rhamnopyranoside [5], kaempferol-3-O- α-L-rhamnopyranosyl (1→6)- β-D-glucopyranoside [6], Luteolin-7-O- β-D-glucopyranoside [7] quercetin 3-O-β-glucopyranoside [8], and quercetin 3,7 di-O- glucopyranoside [9]. Our findings indicated a potent antioxidant activity of V. sativa extract against different radicals (DPPH, superoxide anion, and peroxyl) and an inhibitory activity against carbon tetrachloride-induced lipid peroxidation. compound 6 showed effective inhibitory activity of both peroxyl radicals; compounds 1, 2, 3, 6, 8 and 9 decreased both superoxide anion radical production in PMA-stimulated neutrophil, and compounds 2, 3, 5, and 7 were dramatically effective in inhibition of CCl₄ -induced lipid peroxidation. Additionally, our results revealed that V. sativa extract exhibited inhibitory activity against different inflammatory and nociceptive chemical agents. The purified flavonoids generally showed low anti-inflammatory and antinociceptive activities in a range of 0.9-18.3 % of inhibition, whereas compounds 1, 3, 4, and 8 were the most effective flavonoids. Structure-activity correlation was also discussed. Conclusion: V. sativa extract possessed antioxidant, anti-inflammatory, and antinociceptive activities to variable extents, which may be attributed to the radical scavenging and anti-inflammatory activity of some of its flavonoid constituents. These activities may help in prevention and/or treatment of the pathological disorders in which free radical oxidation, inflammation, and cellular activation are suggested to play a fundamental pathogenic role.