Effect of luteolin on glycoproteins metabolism in 1, 2-dimethylhydrazine induced experimental colon carcinogenesis

We have investigated the effect of luteolin, a flavonoid on coloncancer induced in rats by a colon specific carcinogen 1, 2dimethylhydrazine (DMH). Rats were randomized into 5 groups of10 animals each. Rats in group 1 received 1.0 ml of 0.5%carboxymethyl cellulose (CMC) everyday via intragastric intubationand served as the untreated control. Group 2 rats received luteolinvia intragastric intubation (p.o.) at a daily dose of 0.2 mg/kg bodyweight. The rats in groups 3 to 5 received DMH [20 mg/kg bodyweight] injection once a week subcutaneously for the first 15 weeks.The group 4 rats received luteolin as in group 2 starting one weekbefore the DMH injections and continued till one week after thefinal exposure [DMH + luteolin (Initiation)]. Groups 5 rats receivedluteolin as in group 2 starting one week after the cessation of DMHinjections and continued till the end of the experiment [DMH +luteolin (Post-initiation)]. 20mg/kg body weight of DMH wasadministered subcutaneously once a week for the first 15 weeks andthen discontinued. Luteolin 0.2mg/kg body weight/everyday p.o wasadministered at the initiation and also at the post-initiation stages of carcinogenesis to DMH treated rats. The animals were sacrificed at the end of 30 weeks. The incidence and number of tumors in the colon were significantly higher when the rats were administered DMH, as compared to DMH + luteolin (initiation and postinitiation) groups. Decrease in sialic acid was observed in the colon, intestine and increase in sialic acid was observed in the liver of DMH treated rats as compared to control animals. Increases in glycoconjugates (Total hexoses and fucose) were observed in the DMH treated rats as compared to control animals. Oral administration of luteolin restored the levels of glycoconjugats during DMH induced colon carcinogenesis. Thus, the present study indicates that luteolin has protected the cell surface and maintained the structural integrity of the cell membranes during DMH induced colon carcinogenesis.