Phytochemical profiling and antidiarrheal activity of Sophora japonica L. fruit extract

One of the biggest causes of disease and death worldwide is still diarrhea, particularly affecting children in developing nations. Genus Sophora (Fabaceae) comprises over fifty species known for their diverse bioactive secondary metabolites and notable pharmacological benefits. This investigation aimed to isolate and identify the polyphenol components in an 80% aqueous methanolic extract (AME) of Sophora japonica fruits and to assess its antioxidant and antidiarrheal properties. A castor oil-induced diarrhea model in rats was used to assess antidiarrheal efficacy, with animals divided into five groups: three groups treated with AME at 250, 500, and 1000 mg/kg; a control group; and a reference group treated with loperamide (5 mg/kg). Seven compounds were isolated, including compound 1 (cinnamic acid), compound 2 (gallic acid), compound 4 (rutin), compound 5 (genistein), compound 6 (isoquercitrin), compound 7 (quercetin), and compound 3, a new compound identified as (4'-O-methylgenistein-6'''-acetyl-sophoroside). The extract decreased both total and wet fecal production in a dose-dependent manner. It markedly delayed the onset of diarrhea, demonstrating an antidiarrheal index (ADI) of 71.75, comparable to that of the conventional medication at 1000 mg/kg. These results highlight S. japonica fruit extract as a promising natural source for the development of antidiarrheal agents.