Therapeutic effects of four molecular-weight fractions of Kurozu against dextran sulfate sodium-induced experimental colitis.

Background/aims: Kurozu has been reported to ameliorate colitis in mice and to have an anti-oxidative effect. However, the active components and mechanism of action remain unknown. Here, as a first step to identify the active components, we chromatographically fractionated Kurozu and investigated the anti-colitis activity of the fractions, focusing on anti-nitration activity.

Methods: Kurozu was divided into 4 molecular-weight fractions (fraction I, >4,000 daltons; II, 2,000~4,000 daltons; III, 800~2,000 daltons; IV, <800 daltons). Forty C57black6 mice were divided into 5 groups as follows: the control group received standard CE-2 diet, and Groups I~IV received CE-2 diet containing Kurozu fractions I~IV, respectively. Dextran sulfate sodium was administered to the mice for 12 days to induce colitis. Body weight and bloody stool frequency were monitored as indices of severity of colitis after administration of dextran sulfate sodium, and at 12 days, all mice were sacrificed for examination of colonic pathology and nitrotyrosine production in the colon tissues.

Results: Colitis was markedly ameliorated in Group III, followed by Group II, while Group IV showed little difference from the control. The colonic nitrotyrosine level in Group III was significantly reduced compared with the control.

Conclusions: The major protective components in Kurozu appear to have molecular weights in the range of 800~4,000 daltons, and their action appears to be related, at least in part, to anti-oxidative and anti-nitration effects.