Pharma Easy Notes @Pharmacy

Oxidation of aromatic carbon atom Aromatic hydroxylation refers to the mixed-function oxidation of aromatic compounds (arene) to their corresponding phenols (arenol). The reaction proceeds via the formation of reactive intermediate arene oxide or arene epoxide, which results in multiple reactions. (i) Arene oxide rearranges, rapidly and spontaneously to arenol by an intermolecular hybrid migration called NIH shift. (ii) Nucleophilic attack of water on the epoxide by a microsomal enzyme called epoxide hydrase yield inactive trans dihydro diol metabolite. (iii) Nucleophilic ring opening by GSHS -S- transferase to glutathione adduct. (iv) Because of electrophilic and reactive nature, arene oxide may also react with nucleophilic functionalities present in biomacromolecules. Such reaction leads to modify protein, DNA, and RNA structure that causes serious toxicity. (Did you Know) - An arene or aromatic hydrocarbon is a hydrocarbon with alternative double and single bonds between carbon ato

 

 

Oxidation is the most common reaction in xenobiotics. Oxidation reaction increases the hydrophilicity of the xenobiotics by introducing the polar functional group such as OH. Since only one oxygen atom from the molecular oxygen is incorporated in the product formed, the mixed-function oxidase is also called mono-oxygenase microsomal hydroxylase. The multi-enzyme mixed-function oxidase system consists of 3 components. A heme protein known as cytochrome P4 50 is actually a family of an enzyme. It is a terminal oxidase and plays an important role in transferring oxygen atoms to the substrate RH and convert into ROH. A second enzyme, the flavoprotein known a cytochrome 4 50 reductase which is NADPH dependent. Its functions as an electron carrier, catalyzing the reduction of cytochrome 4 50 to the ferrous form by transferring an electron from NADPH. A heat-stable lipid component is known as phosphatidylcholine . Its function is to facilitate electron transfer from NADPH to cytochrome