Their exogenic function concerns drug metabolism and disposition, pharmaceutical substances, antioxidants, environmental and chemical residues, and finally probiotics disposition. Their endogenous function includes biosynthesis of steroids, bile acids, and vitamin D3 and metabolism of fatty acids, prostaglandins, biogenic amines, and retinoids. Their catalyzing abilities are known for many chemical reactions such as hydroxylation, epoxidation, or heteroatom oxidation. Xenobiotics include commonly used medicines, which will be appropriately metabolized to varying degrees by the aid of cytochromes. The cytochrome P450 (CYP) constitutes a superfamily of hemoproteins that catalyze both endobiotic and xenobiotic substances. A part of its metabolic capacity seems to be in close relation with the presence of the cytochromes on the small intestine. In the recent past, the study and understanding of the intestinal microecology, its metabolic capacity, and its regulation has expanded enormously. There is a tentative multifactorial association of the CYP (P450) cytochrome role in the different diseases states, environmental toxic effects or chemical exposures and nutritional status. The aim of the probiotic approach is to repair the deficiencies in the gut flora and establish a protective effect. The effect of certain bacteria having a benefic action on the intestinal ecosystem has been largely discussed during the past few years by many authors. It is clear that high microbial intestinal charge following intestinal disturbances, ageing, environment, or food-associated ailments leads to the microbial metabolism of a drug before absorption. Compromised intestinal barrier conditions, when rupture of the intestinal integrity occurs, could increase passive paracellular absorption. The high metabolic capacity of the intestinal flora is due to its enormous pool of enzymes, which catalyzes reactions in phase I and phase II drug metabolism. Changes in the pharmacokinetic profile of the drug are associated with increased toxicity due to reduced metabolism, altered efficacy of the drug, increased production of toxic metabolites, and adverse drug interaction. Cytochromes present a genetic polymorphism intra- or interindividual and intra- or interethnic.
CYP1A is expressed at high level in the duodenum, together with less abundant levels of CYP2C8-10 and CYP2D6. CYP3A represents the major intestinal CYP (80%) followed by CYP2C9. CYPs are responsible for the majority of phase I drug metabolism reactions. Human intestine serves primarily as an absorptive organ for nutrients, although it has also the ability to metabolize drugs. The P450 profile of the human intestine has not been fully characterized. In this vein, a plethora of studies were conducted to investigate their role, as cytochromes are located in both liver and intestinal tissues. Cytochromes P450 (CYPs) enzymes metabolize a large variety of xenobiotic substances.
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