Evaluation of the Effect of Picralima Nitida (Apocynaceae) Seed Extract on the Activities of Two Anti-Diabetic Agents

Abstract

Background: Picralima nitida is a tropical plant used mostly in treatment of ailments like fever, hypertension, jaundice, gastro-intestinal disorders and malaria. Several studies have shown its usefulness in treatment of diabetes mellitus. Objective: This study was carried out to investigate the effect of Picralima nitida seed extract on the blood glucose reduction activities of metformin and glimepiride and the effect of Picralima nitida, metformin and glimepiride combinations on liver and blood cells using diabetic albino rat model. Methods: In the first phase of the experiment, the blood glucose reduction effect of metformin, glimepiride and Picralima nitida was determined, the animals were randomly grouped into 7 of 4 rats in a group, first group received ‘high’ dose extract 500mg/kg, Group 2 received ‘low’ dose of extract 250mg/kg, Group 3 was given ‘high’ dose of metformin 100mg/kg, Group 4 was also given ‘low’ dose of metformin 50mg/kg, Group 5 received ‘high’ dose of glimepiride 0.4mg/kg, Group 6 was given ‘low’ dose of glimepiride 0.2mg/kg, Group 7 received water after induction of diabetes mellitus with alloxan. TheGroup 7 received water after induction of diabetes mellitus with alloxan. The basal and 48hour post-induction blood glucose was taken; in all the groups, the blood glucose was taken at 1, 2, 3 and 4 hours after oral administration of the respective anti-diabetic agents and Picralima nitida extract for acute study on the first day. Fasting blood sugar was taken on the 4th and 7th day for sub acute studies. The drugs was given once daily for one week. In the second phase of the experiment, Metformin and Glimepiride was co-administered with Picralima nitida; Rats were grouped into 8, the first four groups was administered withextract-glimepiride combinations of ‘high’ extract 500mg/kg + ‘high’ glimepiride 0.4mg/kg, ‘high’ extract 500mg/kg + ‘low’ glimepiride 0.2mg/kg, ‘low’ extract 250mg/kg + ‘high’glimepiride 0.4mg/kg and ‘low’ extract 250mg/kg + ‘low’ glimepiride 0.2mg/kg doses for 7 days. This was repeated for metformin. Biochemical test was carried out to check the safety of Picralima nitida and anti-diabetics on the liver and blood cell, where liver enzyme parameters such as ALT. AST and ALP were determined, Hematological test such as PCV, HB, WBC and RBC was determined. Results: In the first phase, high dose of Picralima nitida alone showed significant (p<0.05) glucose reduction activity comparable to the high dose of glimepiride 0.4mg/kg and metfomin 100mg/kg. Low dose Picralima nitida 250mg/kg also produced blood glucose reduction that is greater thanglimepiride 0.2mg/kg and 50mg metformin. In the phase two, Picralima nitida 500mg/kg significantly (p<0.05) enhanced the glucose reduction effect of both metformin and glimepiride irrespective of their doses. The biochemical test shows that almost all the combination groups caused a significant (p<0.05) reduction in serum ALT, ALP and AST after a one week treatment, More so, haematological parameters test showed a significant (p<0.05) dose-dependent elevation of RBC, HB, and PCV count. Conclusion: Picralima nitida extract enhanced the blood glucose reduction effect of the oral anti-diabetics, metformin and glimepiride, in diabetic albino rats; therefore, these findings suggest that the co-administration of picralima nitida with anti-diabetic drugs may pose bothpositive and negative clinical implication depending on their dosage