alcohol catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of alcohols, any of a class of compounds containing one or more hydroxyl groups attached to a saturated carbon atom. [GOC:ai]

Alcohol catabolism is a complex process involving the breakdown of ethanol (alcohol) into harmless byproducts. It primarily occurs in the liver, though some alcohol metabolism takes place in the stomach and intestines. The process can be broadly divided into two stages:

**Stage 1: Oxidation to Acetaldehyde**

* **Alcohol Dehydrogenase (ADH):** This enzyme is the primary catalyst in the first step. It converts ethanol into acetaldehyde, using NAD+ as a cofactor. This reaction is reversible, meaning that acetaldehyde can be converted back to ethanol under certain conditions.
* **Microsomal Ethanol Oxidizing System (MEOS):** This system, found in the smooth endoplasmic reticulum of the liver, also contributes to ethanol oxidation. MEOS utilizes cytochrome P450 enzymes and consumes NADPH and oxygen. It becomes increasingly significant at high alcohol concentrations, playing a role in alcohol tolerance and the production of reactive oxygen species.

**Stage 2: Acetaldehyde Oxidation to Acetate**

* **Aldehyde Dehydrogenase (ALDH):** This enzyme oxidizes acetaldehyde into acetate, using NAD+ as a cofactor. This reaction is also reversible.
* **Mitochondrial Aldehyde Dehydrogenase (ALDH2):** This specific form of ALDH is highly active in the mitochondria, playing a crucial role in removing acetaldehyde.

**Fate of Acetate:**

* Acetate is eventually converted into acetyl-CoA, a central molecule in metabolism, which can then enter the citric acid cycle (Krebs cycle) for energy production or be used for fatty acid synthesis.

**Factors Affecting Alcohol Metabolism:**

* **Genetics:** Variations in ADH and ALDH genes can influence the rate of alcohol metabolism and individual susceptibility to alcohol-related effects.
* **Gender:** Women typically have lower levels of ADH, leading to faster blood alcohol concentration (BAC) increases.
* **Age:** Metabolism tends to slow down with age.
* **Nutritional status:** Malnutrition can impair liver function and slow down alcohol metabolism.
* **Other substances:** Medications or other drugs can interact with alcohol metabolism, potentially leading to toxic effects.

**Consequences of Alcohol Metabolism:**

* **Acetaldehyde Toxicity:** Acetaldehyde is a toxic compound that contributes to several adverse effects of alcohol consumption, including flushing, nausea, and headaches.
* **Oxidative Stress:** MEOS activity generates reactive oxygen species, which can damage cells and contribute to liver disease.
* **Dehydration:** Alcohol inhibits the production of antidiuretic hormone (ADH), leading to increased urine production and dehydration.
* **Nutritional Deficiencies:** Alcohol can interfere with the absorption and utilization of essential nutrients, leading to deficiencies.

It's important to note that excessive alcohol consumption can overwhelm the liver's capacity to metabolize alcohol, leading to alcohol poisoning and other health problems.'
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Proteins (1)

Compounds (4)