OBJECTIVE: To study the antihyperglycemic and antinociceptive activities of methanolic extract of the whole plant of Euphorbia thymifolia L., a plant used in folk medicine of Bangladesh for treatment of diabetes and pain.
METHODS: Antihyperglycemic activity studies were conducted in glucose-loaded mice by oral glucose tolerance tests. Mice were given various doses of the extract, followed by glucose (2 g/kg body weight), 1 h after administration of the extract. Serum glucose levels were measured 2 h after glucose administration. Antinociceptive activity studies were conducted in intraperitoneally acetic acid-injected mice through measurement of reductions in abdominal writhing times caused by acetic acid-induced gastric pain. Following a period of 1 h after oral administration of various doses of the extract, all mice received intraperitoneal injection of 1% acetic acid at a dose of 10 mL/kg body weight. To ensure bioavailability of acetic acid, a period of 5 min was given to each animal following which period the number of writhings was counted for 10 min.
RESULTS: The extract caused a significant dose-dependent reduction in serum glucose levels in mice, when administered at doses of 50, 100, 200 and 400 mg/kg body weight as compared to the control animals (P<0.05). The highest reduction of serum glucose (60.5%) was observed at a dose of 400 mg/kg. In comparison, a standard antihyperglycemic drug glibenclamide, when administered at a dose of 10 mg/kg body weight, lowered serum glucose levels by 48.6%. The extract also demonstrated a significant dose-dependent antinociceptive activity compared to control animals (P<0.05). At a dose of 400 mg/kg body weight, the number of abdominal writhings was inhibited by 40.9% as compared to 49.0% inhibition obtained with a standard antinociceptive drug aspirin, administered at a dose of 200 mg/kg body weight.
CONCLUSION: The significant antihyperglycemic and antinociceptive activities demonstrated by the extract validate the use of E. thymifolia in folk medicine of Bangladesh for treatment of diabetes and pain, and merit further scientific studies leading to discovery of efficacious drugs.

Key words: Euphorbia, plant extracts, hypoglycemic agents, analgesics, mice