In vivo analgesic activities and safety assessment of Vitis vinifera   L and Punica granatum   L fruits extracts

Purpose: To investigate the analgesic properties of hydro-alcohol fruit extracts of Vitis vinifera (grape) and Punica granatum (pomegranate) in albino male mice.
Methods: The analgesic activity of the fruit extracts was examined in vivo using thermal stimulus assays (tail immersion and hot plate) and chemically-induced writhing test. The extracts were administered orally at doses of 1.0, 2.0 and 3.0 g/kg. Acetylsalicylic acid (0.1 g/kg, per os) was used as analgesic drug.
Results: In acetic acid writhe test, pre-treatment with both extracts significantly decreased (p < 0.0001) in a dose-dependent manner the number of writhes when compared to control. Vitis vinifera extract treatment caused pain inhibition index values of 36.52 % (1.0 g/kg), 66.67 % (2.0 g/kg) and 89.71 % (3.0 g/kg). Corresponding values for Punica granatum extract treatment were 45.39 % (1.0 g/kg), 70.93 % (2.0 g/kg) and 86.88 % (3.0 g/kg). Acetylsalicylic acid treatment produced 76.06 % of pain inhibition. There were no significant differences (p < 0.05), at equivalent doses of 2.0 and 3.0 g/kg between Vitis vinifera and Punica granatum extract treatments regarding reduction in number of writhes. In hot-plate test, both extracts increased reaction latency time. In tail-immersion assay, Punica granatum significantly increased response to heat stimulus at doses of 2.0 g/kg (p < 0.05) and 3.0g/kg (p < 0.001) compared to control. However, Vitis vinifera did not produce such effects at any of the doses used.
Conclusion: These results show that the hydro-alcohol fruit extract of Punica granatum has a superior analgesic effect to that of Vitis vinifera extract.

Keywords
Vitis vinifera; Pomegranate; Punica granatum; Thermal stimulus assay; Analgesic activity; Pain