Background: Rice bran showed antioxidative, antimutagenic, carcinogenic and antibacterial activities in previous reports. The rice bran has been recently used as a natural source of health food for several diseases such as diabetes, atherosclerosis and cancer. Severe diarrheal disease due to food-borne contamination of bacteria resulted from the bacteria have become resistant to many antibiotics. Hence, early treatment of diarrhea using natural food containing antibacterial activity to prevent progression of severe symptoms will be beneficial.
Objective: To investigate antimicrobial activity of rice bran extracts against bacteria causing diarrheal disease.
Material and Method: Bacterial strains isolated from patients include Vibrio cholerae, Vibrio vulnificus, Salmonella spp, Shigella spp, Escherichia coli (ETEC, EHEC, EAEC, EPEC, EIEC) and Stahylococcus aureus. Rice bran was extracted by five different extraction techniques. The antimicrobial activity was performed by disk diffusion and broth dilution methods.
Results: The results showed that rice bran extracts using different techniques of extraction were able to inhibit the growth of test strains. Rice bran extracts exhibited the most effective antibacterial activity against V. cholerae O139 with MIC value of 0.976 mg/ml. Using ethanol and supercritical techniques, Sang-Yod rice bran showed better antibacterial activity than Jasmine rice bran. In the present study, the MIC values of rice bran extracts against all tested strains except V. cholerae O139 and S. aureus were between 7.812 to 31.25 mg/ml.
Conclusion: The results of present study provide insighful basic knowledge which would lead to develop rice bran extracts for effective treatment of diarrheal disease causing by bacteria including resistant strains. The rice bran extracts used against bacterial infection will be an alternative remedy in order to reduce the incidence of antibiotic resistance in future.

Keywords: Diarrheal disease, Vibrio cholerae, Vibrio vulnificus, Salmonella spp, Shigella spp, E. coli (ETEC, EHEC, EAEC,
EPEC, EIEC) and Stahylococcus aureus, Rice bran extracts