Antioxidant, Analgesic and Toxic Potentiality of Methanolic Extract of Stephania Japonica (thunb.) Miers. Leaf

In the present study crude methanolic extract of Stephania japonica leaf was investigated for possible antioxidant, analgesic and cytotoxic activity. The extract showed antioxidant activity in DPPH radical scavenging activity, nitric oxide scavenging activity and reducing power assays. In both DPPH radical and NO scavenging assay, the extract exhibited moderate antioxidant activity and the IC50 values in DPPH radical scavenging and NO scavenging assays were found to be 105.55 ± 1.06 μg/ml and 129.12 ± 0.15 μg/ml, respectively while the IC50 values of ascorbic acid were 12.30 ± 0.11 μg/ml and 18.64 ± 0.22 μg/ml, respectively. Reducing power activity of the extract increased in a dose dependent manner. Analgesic activity of the crude extract was evaluated using acetic acid-induced writhing model of pain in mice. The crude extract at 200 mg/kg and 400 mg/kg b.w. doses displayed significant (p < 0.001) reduction in acetic acid induced writhing in mice with a maximum effect of 75.89 % reduction at 400 mg/kg b.w. which is comparable to the standard, diclofenac sodium (86.52 %). The extract was also investigated for toxic potentiality using Brine Shrimp lethality bioassay. In this bioassay the extract showed significant toxicity to Brine Shrimp nauplii with the LC50 value of 25.19 ± 0.98 μg/ml. INTRODUCTION: Free radicals contribute to more than one hundred disorders in humans including atherosclerosis, arthritis, ischemia and reperfusion injury of many tissues, central nervous system injury, gastritis, cancer and AIDS 1, . Aerobic cells are endowed with extensive antioxidant defense mechanisms including both low molecular weight scavengers, such as α-tocopherol, cysteine, β carotene, reduced glutathione, ascorbic acid and enzymatic systems, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), glutathione reductase (GSH-Red) and glucose-6phosphate dehydrogenase (G6PD), which counteract the damaging effects of toxic oxygen species. Currently, the possible toxicity of synthetic antioxidants has been criticized. It is generally assumed that frequent consumption of plant-derived phytochemicals from vegetables, fruit, tea, and herbs may contribute to shift the balance toward an adequate antioxidant status . The interest in natural antioxidant, especially of plant origin, has greatly increased in recent years . Thus recent studies have investigated the potential of plant products to serve as antioxidants to protect against various diseases induced by free radicals. Plant products including phenolics, flavonoids, tannins, proanthocyanidins, and various plant or herbal extracts have been reported to be radical scavengers and inhibitors of lipid peroxidation 6, . Pain is a sensorial modality and primarily protective in nature, but often causes discomfort. It is the most important symptom that brings the patient to physician. Analgesics relieve pain