Plant material collection Ripe banana fruits of Musa textilis were collected from Bandarban district in the Chittagong Hill Tracts region. The fruits were brought to Dhaka and identified at the University of Development Alternative.
Preparation of methanolic extract of Musa textilis fruit skins (MEMT) For the preparation of methanol extract of fruit skins of Musa textilis (MEMT), skins were taken off ripe fruits, thoroughly sliced, dried in the shade, and pulverized into a fine powder. 50g of the powder was extracted with 250 ml methanol over 48 hours. Methanol was evaporated at 40oC and the extract was dissolved in Tween 20 prior to administration to mice by gavaging. The final weight of the extract was 6.5g.
Chemicals and Drugs Glibenclamide and glucose were obtained from Square Pharmaceuticals Ltd., Bangladesh. All other chemicals were of analytical grade. Glucometer and strips were purchased from Lazz Pharma, Bangladesh.
Animals Swiss albino mice, which weighed between 12-15g were used in the present study. The animals were obtained from International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B). The animals were acclimatized for three days prior to actual experiments. During this time, the animals were fed with mice chow (supplied by ICDDR,B) and water ad libitum. The study was conducted following approval by the Institutional Animal Ethical Committee of University of Development Alternative, Dhaka, Bangladesh.
Oral glucose tolerance tests for evaluation of antihyperglycemic activity Oral glucose tolerance tests (OGTT) were carried out as per the procedure previously described by Joy and Kuttan with minor modifications. Briefly, fasted mice were grouped into seven groups of five mice each. The various groups received different treatments like Group 1 received vehicle (1% Tween 20 in water, 10 ml/kg body weight) and served as control, Group 2 received standard drug (glibenclamide, 10 mg/kg body weight). Groups 3-5 received, respectively, MEMT at doses of 100, 200 and 400 mg per kg body weight. Groups 6 and 7 received, respectively, 200 and 400 mg MEMT along with 10 mg glibenclamide per kg body weight. All substances were orally administered by gavaging. The amount of Tween 20 administered was same in both control and experimental mice. Following a period of one hour as described earlier, all mice were orally administered 2g glucose per kg of body weight. Blood samples were collected 120 minutes after the glucose administration through puncturing heart following previously published procedures. [6,12] Blood glucose levels were measured with a glucometer. The percent lowering of blood glucose levels were calculated according to the formula described below:
Percent lowering of blood glucose level = (1 – We/Wc) X 100,
Where We and Wc represent the blood glucose concentration in glibenclamide or MEMT or (MEMT + glibenclamide) administered mice (Groups 2-7), and control mice (Group 1), respectively. Gavaging was done carefully such that injuries do not happen, and no mice fatalities occurred during gavaging. Mice were handled carefully throughout the experiment so that they did not get subjected to any unnecessary pain.
Statistical analysis Experimental values are expressed as mean ± SEM. Independent Sample t-test was carried out for statistical comparison. Statistical significance was considered to be indicated by a p value < 0.05 in all cases.