What is drug hydroxylation?
Hydroxylation is the most common reaction type in phase I metabolism and usually produces a chemically stable and more polar hydroxylated metabolite than the drug. From: Developing Solid Oral Dosage Forms (Second Edition), 2017.
What is aromatic oxidation?
(a) Formation of oxygenates without the cleavage of the aromatic rings, e.g., the formation of phenol or benzoquinone from benzene. (b) Formation of oxygenates accompanied by the cleavage of the aromatic rings, e.g., the formation of maleic anhydride from benzene. (c)
What are the phases of drug metabolism?
The metabolism of xenobiotics is often divided into three phases:- modification, conjugation, and excretion. These reactions act in concert to detoxify xenobiotics and remove them from cells.
Where does hydroxylation occur?
Hydroxylation occurs at primary and secondary carbon atoms, but the major hydroxylated metabolite is at the tertiary site (metabolite 1). Hydroxylation at a primary carbon atom (metabolite 2) is followed by two subsequent carbon hydroxylations to produce the carboxylic acid metabolite 3.
What are conjugation reactions?
Conjugation reactions, or phase II reactions, synthesize more water-soluble compounds by combining a substance with an endogenous molecule to enhance excretion of that substance. Glucuronide, sulfate, and glycine are the common endogenous molecules to which drugs are bound.
What is an aromatic carboxylic acid?
Aromatic acids include compounds that contain a COOH group bonded to an aromatic ring. The simplest aromatic acid is benzoic acid. Read More on This Topic. chemical compound: Carboxylic acids. The conjunction of a carbonyl and a hydroxyl group forms a functional group known as a carboxyl group.
What is the order of the oxidation of aromatic hydrocarbons with potassium permanganate?
A relative chemical reactivity order of benzo(a)pyrene>pyrene>phenanthrene>anthracene>fluoranthene>chrysene towards permanganate ion was observed. Aromatic sextet theory was applied to the degradation results to explain the highly variable and compound-specific chemical reactivity order.
What is the purpose of hydroxylation?
Hydroxylation is often the first step in the degradation of organic compounds in air. Hydroxylation is important in detoxification since it converts lipophilic compounds into water-soluble (hydrophilic) products that are more readily removed by the kidneys or liver and excreted.
What happens in a hydroxylation reaction?
Hydroxylation is an oxidation reaction in which carbon–hydrogen (CH) bond oxidizes into carbon–hydroxyl (COH) bond. In organic chemistry, the hydroxylation reaction is mostly mediated by catalysts and heat. Most often the catalysts that mediates the hydroxylation reactions are metal ions.
What is metabolism conjugation?
Conjugates are the end products of the metabolism of many natural and foreign chemicals, and it seems logical in view of the methods then used that they should have been found before the oxidation, reduction, and hydrolysis products of foreign compounds that are usually intermediates in the formation of conjugates.
What drugs are metabolized by glucuronidation?
Affected drugs
- Amitriptyline.
- Clomipramine.
- Clonazepam.
- Diazepam.
- Flunitrazepam.
- Lorazepam.
- Nitrazepam.
- Oxazepam.
Why is aromatic hydroxylation such a common metabolic event?
The frequency of aromatic hydroxylation as a metabolic event is undoubtedly a reflection of the commonality of an aromatic ring as a structural component of many drugs. While a phenol is usually not the major metabolite of such a drug, it often is found as a significant contributor to the metabolism of that drug.
What is selective hydroxylation of aromatics?
Selective hydroxylation of aromatic compounds is among the most challenging chemical reactions in synthetic chemistry and has gained steadily increasing attention during recent years, particularly because of the use of hydroxylated aromatics as precursors for pharmaceuticals. Biocatalytic oxygen tra …
Can aromatic hydroxylation be described using curve-crossing diagrams?
Recently, aromatic hydroxylation has also been described using VB curve-crossing diagrams (108 ). The cytochromes P450 hydroxylate arenes as a means of detoxification in the body. The activation of aromatic substrates by P450 enzymes generates several products, including phenols, arene oxides, and ketons.
Is benzene aromatic or aromatic hydroxylated?
In the case of benzene, the para position is often favoured. An example of a drug that undergoes aromatic hydroxylation is phenobarbital. The CYP450 enzymes have rich chemistry and the diagram shown below is a small subset of reactions they can catalyse (see below). Drug metabolism is often considered during drug design.