Kratom (Mitragyna speciosa (Korth.) Havil.) is a tropical tree indigenous to Thailand. In traditional medicine, it has been used to treat diarrhea, peptic ulcer, stomach ache or gastric upsets. In this study, the protective effects of a methanolic extract of kratom leaves on peptic ulcer models and reflux esophagitis in rats were studied. A methanolic extract of kratom leaves at a dose of 200 and 400 mg/kg were tested in rats on three induced peptic ulcer models and reflux esophagitis. The peptic ulcer models were induced by water immersion restraint (WIR) stress, alcohol treatment, and acetylsalicylic treatment. The methanolic extract of mitragynine from kratom leaves and ranitidine decreased the ulcer index significantly in the WIR stress model. Conclusion: Only 400 mg/kg of methanolic extract of kratom leaves and omeprazole decreased the ulcer index in the alcohol and acetylsalicylic acid induced ulcer models. No protective effect of kratom extract was found on the reflux esophagitis model.
