The colon is largely being investigated as a site for administration of protein and peptides, which are degraded by digestive enzymes in the upper GIT. Also for local diseases of the colon such as inflammatory bowel disease, colorectal cancer and ameobiasis, drug administration to the site of action can not only reduce the dose to be administered, but also decrease the side effects. Inflammatory Bowel Disease (IBD) such as Ulcerative colitis and Crohn's disease are characterized by chronic intestinal inflammation. Intestinal bacteria initiate the activation of intestinal inflammatory processes, which are mediated by pro-inflammatory cytokines and chemokine. Increased chemokine expression has also been observed in epithelial cells, endothelial cells, and smooth muscle cells. Future trials of specific agents capable of inhibiting chemokine synthesis and secretion or blocking chemokine-chemokine receptor interaction will be important to study in patients with ulcerative colitis and Crohn's disease. Many important bioactive compounds have been discovered from natural sources using bioactivity directed fractionation and isolation (BDFl) Continuing discovery has also been facilitated by the recent development of new bioassay methods. These bioactive compounds are mostly plant secondary metabolites, and many naturally occurring pure compounds have become medicines, dietary supplements, and other useful commercial products. The present review includes various approaches investigated for colon drug delivery and their site specificity. To achieve successful colonic delivery, a drug needs to be protected from absorption and the environment of the upper gastrointestinal tract and then be abruptly released into the proximal colon, which is considered the optimum site for colon targeted delivery of drugs.
Keywords: colon targeted delivery, natural product, bioactivity isolation, inflammation, colon disease, natural source carrier, ulcerative colitis, Crohn's disease, bioactivity directed fractionation and isolation (BDFl), pro-inflammatory cytokines, chemokine
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