Evaluation of the antinociceptive activity of Amaranthus hybridus Linn. root extracts

The work evaluated the antinociceptive activity of Amaranthus hybridus Linn. root extracts using the central and peripheral antinociceptive experimental animal models. The oral administration of ethanol and aqueous root extracts (100 and 200 mg/kg) produced significant (p < 0.01) and dose dependent results compared to their respective controls. The aqueous extract (200 mg/kg) produced more inhibition of abdominal writhes in mice than the other test extracts. Both the test extracts significantly (p < 0.01) and dose dependently increased the hot plate pain threshold in mice but the aqueous extract (200 mg/kg) was exhibiting more increase in pain threshold than the other test doses of extracts. Dose dependent and significant (p < 0.01) reduction of painful sensation in mice tail immersion test due to oral administration of test doses was also observed. Oral acute toxicity study indicated the non toxic nature of root extracts. The present investigation revealed that ethanol and aqueous root extracts of A. hybridus Linn. possess significant and dose dependent central and peripheral antinociceptive activity justifying its traditional use in treating conditions associated with painful conditions.