Analgesic and antioxidant activities of Colocasia fallax

The ethanol extract of tuber part of Colocasia fallax Schott (Araceae) was tested for its potential analgesic and antioxidant activities. Acetic acid induced writhing method was used to evaluate the analgesic activity at the concentration of 250 and 500 mg/kg body weight. In order to investigate the antioxidant activity, four complementary test systems, namely, 2,2-diphenyl-1-picryl-hydrazil (DPPH) free radical scavenging, ferric reducing power assay, total phenolic and flavonoid contents were used. Polyphenolic compounds were also detected by HPLC analysis. The extract showed significant (P < 0.005) analgesic activity with 32.14 and 53.57 % writhing inhibition at the concentrations of 250 and 500 mg/kg body weight, respectively that was comparable to standard diclofenac sodium (78.57 % at 25 mg/kg). In DPPH radical scavenging assay, the extract showed the IC50 value of 78.94 μg/ml. Reducing power of the extract was comparable to that of butylated hydroxy toluene (BHT). In HPLC analysis of polyphenols, epicatechin, myricetin, trans-cinnamic, syringic acid, vanillin, p-coumaric acid, trans-ferulic acid and rosmarinic acid were detected in the extract (95.95, 52.14, 20.39, 8.32, 8.43, 6.36, 4.18 and 6.73 mg/100 g of dry extract, respectively). Presence of polyphenols in the extract might have attributed towards the observed bio-activity. Present finding also suggests the traditional use of this plant in the management of pain.