RESUMO
PURPOSE: Psidium guajava L. (Family, Myrtaceae) is reportedly used in ethnomedicine for the treatment of diarrhoea, inflammation, and gastroenteritis. OBJECTIVE: This study evaluated the gastrointestinal function of Psidium guajava leaf extract (PGLE) in rats and rabbits. MATERIALS AND METHODS: Crude ethanolic PGLE was subjected to phytochemical and toxicity tests (acute and sub-acute). Standard analytical procedures were employed to evaluate the in vivo gastrointestinal motility, and gastroprotective effect of PGLE against aspirin-induced ulcers. RESULTS: In the phytochemical analysis, phenols were the highest (48.32 mg) followed by flavonoids (32.74 mg) and least in tannins (7.31 mg). The acute toxicity of PGLE was >6000 mg/kg. Administration of PGLE decreased significantly (p < 0.05) the body weight, while the liver biomarkers were not significantly altered (p > 0.05) when compared to the control. PGLE significantly increased extractible mucus weight and lowered gastric acid secretion in rats (p < 0.05). PGLE decreased significantly (p < 0.05) ulcer scores and indexes, and increased percentage ulcer inhibition in a dose-dependent manner compared to the negative and omeprazole-treated groups. PGLE dose-dependently inhibited basal amplitudes of contractions, and significantly inhibited acetylcholine-induced contractions, terminating them completely at higher doses. CONCLUSION: PGLE may be a good anti-ulcer and anti-diarrhoeal agent, raising the prospect of novel drug development for such applications.