Extraction of plant parts: Leaves of both Derris scandens and Thunbergia erecta were collected from Jahangir Nagar University Campus, Savar, Dhaka, Bangladesh in the month of April 2017. Identification of these plant parts was confirmed at the Bangladesh National Herbarium. ACCN of Derris scandens and Thunbergia erecta were 46542 and 45803 respectively those along with sample specimens of both were kept at herbarium for future reference.
After collection, the leaves of both plants were dried in the shade of sunlight for four days. Then dried leaves were crushed into a coarse powder using blender machine. About 450g and 750g of prepared powder of Derris scandens and Thunbergia erecta leaves respectively were macerated in methanol for 7 days. After filtration by cotton filter the filtrates were concentrated at 39°C with the aid of rotary evaporator. Air drying of the concentrated filtrates yielded to 30g and 25g methanol extract of Derris scandens and Thunbergia erecta respectively.
Animals: Swiss albino mice of both sexes compatible for 20-25g of weight were selected for conducting in vivo hypoglycemic effect evaluation. Prior to one week the mice were purchased from ICDDR, B (International Centre for Diarrhoeal Disease Research, Bangladesh) and preserved in the laboratory keeping optimum ambience (temp. 25±2°C and humidity 55-60 %). Experimental animals were kept on 12 hrs dark-light cycle so that they could be used to with the experimental environment. Standard food supplied by ICDDR, B along with ample fresh water was allowed to take. Before 12 hrs of experiment, mice were kept under starvation and allowed only to have fresh water ad libitum. The Ethics Committee of Stamford University Bangladesh (SUB/IAEC/18.01) approved all experimental protocols.
Chemicals and drugs: Following chemicals and drugs were used in the experiment: Reagent grade methanol (Merck, Germany), dimethyl sulfoxide (Merck, Germany), 2,2-diphenyl-1- picrylhydrazyl (Sigma-Aldrich, USA), glucose (Glaxo Smith Kline) and Glibenclamide (Square Pharmaceuticals).
Hypoglycemic effect evaluation: In this study, a total eight groups of mice (n=5) were used and all mice were loaded by glucose to make the simulation as diabetic state. Groups were designated by Gr-1 to Gr-8 while Gr-1(control) was treated by vehicle, Gr-2(Std) was treated by glibenclamide. Rest six groups of mice were treated by three doses (100mg/Kg BW, 200mg/Kg BW and 400mg/Kg BW) of each plant extracts. Thus MEDS was subjected to Gr-3 to 4 and METE was given to Gr-5 to 8. All treatments were administered by oral route and all mice groups were allowed to take 2gm glucose/kg one hour after the completion of oral gavage of extracts, glibenclamide and 0.1% v/v DMSO in normal saline (vehicle). Blood sugar level after two hours of treatment was measured by glucometer which works following glucose oxidation method.
Percent of Blood sugar lowering was calculated following the formula given hereunder 21.
Percent lowering of blood glucose level = (1 – We/Wc) x 100,
Where We and Wc stand for the blood glucose concentration measured in glibenclamide or extracts administered mice and control mice respectively.
STATISTICAL ANALYSIS: Statistical analysis of the hypoglycemic study involves the use of ANOVA followed by Dunnett’s post hoc test with IBM statistics data editor. Graphical presentation was executed by Graphpad prism 7 software.