Phytochemical screening and study of antioxidant and analgesic potentials of ethanolic extract of Stephania japonica Linn.

Abstract

The present study was conducted to evaluate the possible phytochemicals present, antioxidant activity and analgesic potential of ethanolic extract of leaves of Stephania japonica (Linn.). For investigating the antioxidant activity, four complementary test systems, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, reducing power assay, Fe++ ion chelating ability and total phenolic content were used. Analgesic activity of the extract was evaluated using acetic acid-induced writhing model of pain in mice. In DPPH free radical scavenging test, IC50 value for ethanolic crude extract was found moderate (18.57 ± 0.079 μg/ml) while compared to the IC50 values of the reference standards ascorbic acid and BHA (1.93 ± 0.027 and 4.10 ± 0.035 μg/ml), respectively. In reducing power assay, the maximum absorbance for ethanolic crude extract was found to be 2.013 ± 0.024 at 100 μg/ml, compared to 2.811 ± 0.013 and 2.031 ± 0.019 for standard ascorbic acid and butylated hydroxyanisole (BHA), respectively. The IC50 value of the extract as % Fe++ ion chelating ability was determined as 18.68 ± 0.029, where ethylenediaminetetraacetic acid (EDTA) showed 8.87 ± 0.035. The total phenolic amount was also calculated as moderate in ethanolic crude extract (237.71 ± 0.57 mg/g of gallic acid equivalent). At the dose of 500 mg/kg body weight, the extract showed significant analgesic potential in acetic acid induced writhing in mice, showing 41.47% inhibition (P < 0.001) comparable to that produced by diclofenac Na (45.02%) used as standard drug. These results show that ethanolic extract of leaves of S. japonica (Linn.) has moderate antioxidant and potent analgesic activity. These activities increase with the increase of concentrations. The potency of the extract may be due to the presence of phytochemicals like tannins, flavonoids, phenolics etc.   Key words: Antioxidant, analgesic, phytochemicals, 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic content, reducing power assay, Stephania japonica, Menispermiaceae.