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Purpose: To investigate the effects of an aqueous extract of unpolished dark purple glutinous Thai rice, variety Luem pua (LP), in two rat models of inflammatory bowel disease (IBD). Methods: Polyphenolic compounds content were determined by HPLC methods and antioxidant activities by DPPH and FRAP assays of the LP extract. The effect of the LP extract at 5 g/kg/day were evaluated in two rat models of IBD that included acetic acid and indomethacin induced IBD. On each day of treatment, changes of body weight, stool consistency and stool blood were scored and expressed as disease activity index (DAI). At the end of the experiments, the animals were euthanized. Colon length and spleen weight were determined, and the degree of inflammation of the colon was scored. Results: Rats in both models of IBD (acetic acid- and indomethacin-induced IBD), exhibited significant increases in DAI, macroscopic inflammation scores and spleen weights, while the lengths of colon were decreased. Pretreatment with LP extract attenuated the disease severity in both models as seen by the reverse of all observed altered parameters. Conclusion: These data suggest that LP extract might be beneficial in preventing and/or treating IBD. Keywords: Inflammatory bowel disease (IBD), Dark purple glutinous rice Var. Luem Pua, Acetic acid, Indomethacin

Objective: The objective of the study was to investigate the effect of aqueous extract of unpolished dark purple glutinous Thai rice variety Luem Pua(LP) in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in rat and the possible cholinomimetic effects of the extract.Methods: The effect of LP extract (0.5, 1, or 1.5 mg/ml final concentration) on ileum contraction was tested using isolated guinea pig ileum. Certainagonists (acetylcholine, tetramethylammonium, and clonidine) and antagonists (hexamethonium chloride and atropine) were studied to determinethe cholinomimetic effect of the extract. The effects of LP extract (5 g/kg/day) in DSS-induced UC model (drinking water was replaced with 3%DSS in water for 7 days) in rat were evaluated. On each day of treatment, the change of disease activity index (DAI) was recorded. At the end of theexperiments, rats were terminated and disease severity expressed as DAI, colon length, and spleen weight were determined.Results: LP extract at the concentration of 0.5, 1, and 1.5 mg/ml (final concentration) could contract the ileum in a dose-dependent manner and beblocked completely by atropine. Oral administration of LP extract could significantly attenuate the severity of DSS-induced UC as seen by the reductionof DAI, colon length, and spleen weight.Conclusion: Results in isolated guinea pig ileum suggest that LP might contain active substance that could activate muscarinic receptors. In additionto antioxidant activity, through activation of muscarinic receptor, might explain the protective effects of LP extract against DSS-induced UC in rats.