143 Advances in Natural and Applied Sciences, 7(2): 143-148, 2013 ISSN 1995-0772 This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLE Corresponding Author: Dr. Mohammed Rahmatullah, Pro-Vice Chancellor and Dean, Faculty of Life Sciences University of Development Alternative House No. 78, Road No. 11A (new) Dhanmondi, Dhaka-1205 Bangladesh Tel: +88-01715032621; Fax: +88-02-815739; E-mail: rahamatm@hotmail.com Evaluation of antihyperglycemic and antinociceptive potential of Colocasia esculenta (L.) Schott (Araceae) leaves Afsana Akter, Shiblur Rahman, Md. Tanvir Morshed, Sophia Hossain, Sharmin Jahan, Auditi Swarna, Mohammed Rahmatullah Faculty of Life Sciences, University of Development Alternative, Dhanmondi, Dhaka-1205, Bangladesh. Afsana Akter, Shiblur Rahman, Md. Tanvir Morshed, Sophia Hossain, Sharmin Jahan, Auditi Swarna, Mohammed Rahmatullah: Evaluation of antihyperglycemic and antinociceptive potential of Colocasia esculenta (L.) Schott (Araceae) leaves ABSTRACT The antihyperglycemic and antinociceptive potential of Colocasia esculenta leaves, a plant used in folk medicines of Bangladesh for treatment of pain, inflammation, and lowering of blood sugar were investigated. In antihyperglycemic activity tests conducted with glucose-loaded Swiss albino mice, methanolic extract of leaves significantly and dose-dependently reduced blood sugar concentrations. At extract doses of 50, 100, 200 and 400 mg per kg body weight mice, the percent lowering of blood sugar by the extract was, respectively, 22.5, 23.8, 25.7, and 35.9. The results were both dose-dependent and statistically significant. A standard antihyperglycemic drug, glibenclamide, when administered to glucose-loaded mice, reduced blood sugar level by 44.7%. The results demonstrate that the methanolic extract possesses antihyperglycemic potential. In antinociceptive activity tests conducted with intraperitoneally administered acetic acid-induced gastric pain model in mice, the extract at the afore-mentioned four doses dose-dependently reduced the number of writhings in mice caused by the gastric pain, respectively, by 36.4, 57.6, 63.6, and 66.7%. The results were statistically significant at all doses of the extract. A standard antinociceptive drug, aspirin, when administered at doses of 200 and 400 mg per kg body weight, reduced the number of writhings by 27.3 and 36.4%, respectively. The results thus demonstrate also significant antinociceptive potential of leaves of the plant, which was greater than the higher dose of the standard drug, aspirin, at the three highest doses of the extract tested. Taken together, the results validate the folk medicinal uses of the plant for treatment of pain and for lowering blood sugar level in diabetic patients. Key words: Colocasia esculenta, antihyperglycemic, antinociceptive, Araceae Introduction Colocasia esculenta (L.) Schott (Araceae) is a tropical plant grown primarily for its edible corms. In Bangladesh, the plant can be found both in the wild as well as cultivated and is known in the Bengali language as pani kochu. Anti-cancer effects of corms of the plant on colonic adenocarcinoma cells in vitro have been reported (Brown et al., 2005). Anti-diabetic activity of ethanol extract of leaves of the plant has been shown in alloxan-induced diabetic rats (Kumawat et al., 2010). Aqueous extract of the leaves have reportedly demonstrated anti-hypertensive and diuretic effects (Vasant et al., 2012). Phytochemical investigations on leaves have revealed the presence of orientin, isoorientin, isovitexin, orientin-7-O-glucoside, isovitexin-3´-O- glucoside, and luteolin-7-O-glucoside (Halligudi, 2013). The leaves of the plant are used by folk medicinal practitioners of Bangladesh for treatment of pain, inflammation, and for lowering of blood sugar levels in diabetic patients. Ongoing studies by our research group have centered on ethnomedicinal surveys (Rahmatullah et al., 2009a-c; Rahmatullah et al., 2010a-g; Rahmatullah et al., 2011a,b; Rahmatullah et al., 2012a-d) followed by screening of the plants obtained for antihyperglycemic, antinociceptive and cytotoxic activities (Anwar et al., 2010; Jahan et al., 2010; Khan et al., 2010; Mannan et al., 2010; Rahman et al., 2010; Rahmatullah et al., 2010h; Shoha et al., 2010; Ali et al., 2011; Barman et al., 2011; Hossan et al., 2011; Jahan et al., 2011; Rahman et al., 2011; Sutradhar et al., 2011; Ahmed et al., 2012; Arefin et al., 2012; Haque et al., 2012; Sathi et al., 2012). As part of the screening process to locate plants with antihyperglycemic and antinociceptive properties, this study was conducted to evaluate the above two properties of methanolic extract of leaves of Colocasia esculenta in Swiss albino mice.