Metabolism Gut flora

this diagram shows biosynthesis of bioactive compounds (indole , other derivatives) tryptophan bacteria in gut. indole produced tryptophan bacteria express tryptophanase. clostridium sporogenes metabolizes tryptophan indole , subsequently 3-indolepropionic acid (ipa), highly potent neuroprotective antioxidant scavenges hydroxyl radicals. ipa binds pregnane x receptor (pxr) in intestinal cells, thereby facilitating mucosal homeostasis , barrier function. following absorption intestine , distribution brain, ipa confers neuroprotective effect against cerebral ischemia , alzheimer’s disease. lactobacillus species metabolize tryptophan indole-3-aldehyde (i3a) acts on aryl hydrocarbon receptor (ahr) in intestinal immune cells, in turn increasing interleukin-22 (il-22) production. indole triggers secretion of glucagon-like peptide-1 (glp-1) in intestinal l cells , acts ligand ahr. indole can metabolized liver indoxyl sulfate, compound toxic in high concentrations , associated vascular disease , renal dysfunction. ast-120 (activated charcoal), intestinal sorbent taken mouth, adsorbs indole, in turn decreasing concentration of indoxyl sulfate in blood plasma.

without gut flora, human body unable utilize of undigested carbohydrates consumes, because types of gut flora have enzymes human cells lack breaking down polysaccharides. rodents raised in sterile environment , lacking in gut flora need eat 30% more calories remain same weight normal counterparts. carbohydrates humans cannot digest without bacterial include starches, fiber, oligosaccharides, , sugars body failed digest , absorb lactose in case of lactose intolerance , sugar alcohols, mucus produced gut, , proteins.

bacteria turn carbohydrates ferment short-chain fatty acids (scfas) form of fermentation called saccharolytic fermentation. products include acetic acid, propionic acid , butyric acid. these materials can used host cells, providing major source of useful energy , nutrients humans, helping body absorb essential dietary minerals such calcium, magnesium , iron. gases , organic acids, such lactic acid, produced saccharolytic fermentation. acetic acid used muscle, propionic acid helps liver produce atp, , butyric acid provides energy gut cells , may prevent cancer. evidence indicates bacteria enhance absorption , storage of lipids , produce , facilitate body absorb needed vitamins vitamin k.

gut flora synthesize vitamins biotin , folate, , absorption of dietary elements including magnesium, calcium , iron. methanogenic archaea such methanobrevibacter smithii involved in removal of end products of bacterial fermentation such hydrogen.