Background: Hyperglycemia is one of the serious problems that affect humans' lifestyle and can be require special treatments. Abusive and/or incorrect use of synthetic drugs results in side effects and other problems. People with diabetes need safer and more effective anti-diabetic drugs that can decrease diabetic associated chronic complications. Treatment of the disease began long ago with the use of herbs. Natural products are harmless is due to several reasons, namely, conventional medicine can be inefficient (e.g. side effects and ineffective therapy).
Objective: Evaluate the hypoglycemic and anti- hyperglycemic activity and to prove in vivo antioxidant potential of aqueous leaves extracts of Psidium guajava and olive in Streptozotocin-Nicotinamide induced hyperglycemic rats and find out sub chronic toxicity of these herbal anti-diabetic formulae on pancreas, and liver in experimental animals.
Methods: Forty- two adult males albino rats, weighting (140-150 grams) used in the present study. Rats were assigned to one of seven groups of six animals each (n= 6). Hyperglycemia induced by single dose intraperitoneal injection of STZ - NIN (60 mg/kg - 110 mg/kg, b.wt i.p.) the control groups was given distilled water, the experimental sub-groups were started one week later of STZ induction, then treated once daily by the aqueous extracts of Psidium guajava leaves and olive leaves that prepared for treated until the end of the experiment. Initially, blood samples taken for measured glucose levels and HbA1c. The body weight, urine sugar and blood glucose levels we checked regularly. Finally, the serum lipid profiles and other biochemical parameters as well as the antioxidants level parametars of diabetic rats treated estimated at the end of experimental period.
Results: Studies have confirmed that antioxidant activity of plant extracts depends on the concentration of phenolic compounds. The phenolic contents of guava leaves and olive leaves extracts were found to be (227.63 and 106.33 mg GAE /g. Ex) respectively, while total flavonoids content were (79.96 and 63.63 mg QE/g. Ex) respectively. DPPH scavenging appeared antioxidant activity (58.72 % & 51.67 %) respectively. While the methanolic guava leaf extracts the more effective one compared with olive leaf extract. Oral acute toxicity study, observed has shown no acute toxicity to diabetic rats treated. However, caused a significant decrease in blood glucose levels, HbA1c, and altered lipid profiles (Triglyceride and total cholesterol); whereas an increase in HDL-C levels was seen with significant changes in LDL-C values, and other biochemical parameters level was observed in diabetic rats after administering for eight- weeks treatment, antioxidants levels were reversed to near normal compared to diabetic control rats.
Conclusion: It appears that aqueous extracts of Psidium guajava leaves and olives leaves possess significant anti-diabetic, and effective in lowering blood glucose level but lack hypoglycemic effect in hyperglycemic rats. Guava leaves extracts contain alkaloids, tannins, saponins, large content of phenols, and flavonoids that could be responsible for the observed anti-hyperglycemic effect. Further studies warranted to elucidate possible mechanism(s) of action of the plant material.