Objective
Psidium guajava occurs worldwide in tropical and subtropical areas. It has been used to treat inflammation, diabetes, fever, hypertension and ulcers. However, its antidiarrheal and protein conservative activities still need to be investigated.
Methods
Fifty-four male rats were divided into normal and diarrheal rats. The normal rats were divided into 4 groups: control, low-dose P. guajava leaf extract (50?mg/kg), high-dose P. guajava leaf extract (100?mg/kg) and gallic acid. Treatments were administrated orally in 1?mL saline for a 1-month period. The diarrheal rats were divided into 5 groups: desmopressin (0.2?mg/kg) drug, low-dose P. guajava leaf extract (50?mg/kg), high-dose P. guajava leaf extract (100?mg/kg), gallic acid and an untreated control. Doses were given daily for a 1-month period while the untreated control received no treatment.
Results
Diarrhea was responsible for an observed decline in kidney weight and serum sodium, potassium and chloride. Further, diarrhea was positively correlated with a significant increase in urine volume, and excretion of electrolytes, serum urea, creatinine and uric acid in the urine. In contrast, there was a proportional increase in the lipid peroxidation value in diarrhea and a significant decline was observed in serum superoxide dismutase, glutathione peroxidase and glutathione levels in diarrhea. Also, diarrhea inhibited blood proteins. The oral intake of P. guajava leaf extract by diarrheal rats restored all of these parameters to near normal levels. High-dose P. guajava leaf extract was more effective than the same compound at a low dose.
Conclusion
P. guajava leaf extract elicited antidiarrheal and protein conservative effects.

Key words: Psidium guajava, Myrtaceae, Diarrhea, Proteins, Antioxidant