Antihyperglycaemic and antinociceptive activity evaluation of methanolic extract of whole plant of Amaranthus tricolour L. (Amaranthaceae).

Amaranthus tricolor whole plants are used by folk medicinal practitioners of Bangladesh for treatment of pain, anaemia, dysentery, skin diseases, diabetes, and as a blood purifier. Thus far, no scientific studies have evaluated the antihyperglycaemic and antinociceptive effects of the plant. The present study was carried out to evaluate the possible glucose tolerance efficacy of methanolic extracts of A. tricolour whole plants using glucose-induced hyperglycaemic mice, and antinociceptive effects with acetic acid-induced gastric pain models in mice. In antihyperglycaemic activity tests, the extract at different doses was administered one hour prior to glucose administration and blood glucose level was measured after two hours of glucose administration (p.o.) using glucose oxidase method. The statistical data indicated the significant oral hypoglycaemic activity on glucose-loaded mice at all doses of the extracts tested. Maximum antihyperglycaemic activity was shown at 400 mg extract per kg body weight, which was comparable to that of a standard drug, glibenclamide (10 mg/kg body weight). In antinociceptive activity tests, the extract also demonstrated a dose-dependent significant reduction in the number of writhings induced in mice through intraperitoneal administration of acetic acid. Maximum antinociceptive activity was observed at a dose of 400 mg extract per kg body weight, which compared favourably with that of a standard antinociceptive drug, aspirin, when administered at a dose of 200 mg per kg body weight. The results validate the folk medicinal use of the plant for reduction of blood sugar in diabetic patients as well as the folk medicinal use for alleviation of pain. The results suggest that this plant may possess further potential for scientific studies leading to possible discovery of efficacious antihyperglycaemic and antinociceptive components.