Metabolism of Xenobiotic Quiz

Questions and Answers

What is the primary substrate for glucuronidation?

UDP glucuronic (correct)

S-adenosyl methionine

Acetyl CoA

PAPS

Which enzyme is responsible for the process of glucuronidation?

Glutathione S-transferase

Glucuronyltransferase (correct)

Sulfotransferase

Acetyltransferase

What substance is formed when tryptophan undergoes sulfation?

Glutathione

Bilirubin

Indol

Indoxyl sulfate (correct)

What is a consequence of low glutathione levels in tissues?

Increased susceptibility to chemical injury Signup and view all the answers

Which compound acts as the active sulfate donor in sulfation?

PAPS Signup and view all the answers

What is a xenobiotic?

A compound that is foreign to the body Signup and view all the answers

Which organ is primarily responsible for biotransformation of xenobiotics?

Liver Signup and view all the answers

Which phase of xenobiotic metabolism primarily involves hydroxylation?

Phase 1 Signup and view all the answers

What role do prodrugs play in xenobiotic metabolism?

They convert inactive xenobiotics into active metabolites. Signup and view all the answers

Which of the following effects is NOT associated with xenobiotics?

Induction of antibody formation by themselves Signup and view all the answers

Which reaction is catalyzed by Mono-oxygenases in phase 1 metabolism?

Hydroxylation Signup and view all the answers

What is a common result of xenobiotic exposure in terms of DNA?

Mutation leading to cancer Signup and view all the answers

What cofactor is involved in the reactions of cytochrome P450 during phase 1 metabolism?

NADPH+H Signup and view all the answers

What effect does erythromycin have when taken with mevastatin?

It increases mevastatin levels in the blood. Signup and view all the answers

Which CYP enzyme is primarily involved in the activation of carcinogenic substances from polycyclic aromatic hydrocarbons?

CYP1A1 Signup and view all the answers

How many functional cytochrome P450 genes do humans have?

57 Signup and view all the answers

Which of the following correctly describes CYP nomenclature?

CYP followed by an Arabic numeral, a capital letter, and another numeral. Signup and view all the answers

What defines obesity according to the provided content?

A condition where energy intake exceeds energy expenditure. Signup and view all the answers

What is the primary method used for diagnosing obesity?

Body Mass Index (BMI). Signup and view all the answers

Which statement regarding most cytochrome P450 enzymes is correct?

They are inducible and synthesized in response to xenobiotics. Signup and view all the answers

Which of the following correctly describes energy intake?

It occurs by eating and drinking consumption. Signup and view all the answers

What is the primary function of methyl transferase in xenobiotic metabolism?

To facilitate the transfer of methyl groups Signup and view all the answers

What is the main aim of the phase 1 and phase 2 reactions in xenobiotic metabolism?

To increase the solubility of xenobiotics Signup and view all the answers

Which of the following statements is true about Cytochrome P450?

It contains a heme group that binds oxygen. Signup and view all the answers

What percentage of total drug metabolism is attributed to Cytochrome P450 enzymes?

75% Signup and view all the answers

What factors can influence the activity of Cytochrome P450 enzymes?

Age, gender, and disease Signup and view all the answers

How do many drugs interact adversely with CYP enzymes?

By inducing the biosynthesis of CYP Signup and view all the answers

What is a potential consequence of CYP's role in drug metabolism?

Increased cellular mutation risk Signup and view all the answers

Which drug interaction example was mentioned regarding mevastatin?

Erythromycin inhibits the metabolism of mevastatin. Signup and view all the answers

What is the initial treatment goal for weight loss?

5% to 10% of total weight Signup and view all the answers

Which of the following choices is NOT recommended as a part of dietary changes?

Consuming higher salt and sugar Signup and view all the answers

What is the typical recommended calorie intake for women aiming to lose weight?

1,200 to 1,500 calories Signup and view all the answers

How much physical activity is recommended weekly for obesity treatment?

150 minutes Signup and view all the answers

Which type of exercise is considered the most efficient way to burn calories?

Aerobic exercise Signup and view all the answers

What type of oils are recommended for replacing fats in the diet?

Olive, canola, and nut oils Signup and view all the answers

Which component is NOT a part of the treatment strategy for obesity?

Surgery Signup and view all the answers

What is suggested for maintaining weight loss after initial treatment?

Continue with at least 150 minutes of exercise a week Signup and view all the answers

Study Notes

Metabolism of Xenobiotics

Xenobiotic: A substance foreign to the body, including drugs, insecticides, and carcinogenic chemicals.
Body's defense against xenobiotics includes redistribution, excretion, and metabolism, with metabolism being the primary mechanism.
Biotransformation primarily occurs in the liver, which acts as a metabolic clearing house.
The intestine serves as the initial site for drug metabolism and other organs like the lung, brain, and kidney are also involved.
Xenobiotics can cause cell injury by binding to DNA, RNA, and proteins, leading to compromised cellular integrity.
They may stimulate antibody production only when combined with cellular proteins, causing further cellular damage.
Potential effects include carcinogenesis via DNA damage and impaired repair processes.

Phases of Xenobiotic Metabolism

Phase 1: Involves drug modification primarily through hydroxylation, catalyzed by cytochrome P450 (CYP).
- Other reactions include oxidation, reduction, and hydrolysis.
- Some xenobiotics are converted from inactive to active forms (prodrugs).
Phase 2: Focuses on conjugation processes like glucuronidation, sulfation, acetylation, and methylation.
- Glucuronidation: Conjugation with glucuronic acid via UDP glucuronic acid; bilirubin and certain acids are excreted as glucuronides.
- Sulfation: Involves sulfate conjugation mediated by PAPS; affects alcohol, phenols, and steroids.
- Glutathione Conjugation: Protects against toxic compounds; glutathione S-transferase facilitates this process.
- Both phases aim to make xenobiotics more soluble for easier excretion in urine or stool.

Cytochrome P450 (CYP)

CYPs are hemoproteins primarily found in the liver, gut, and other organs, playing a vital role in drug metabolism.
They participate in both Phase 1 and Phase 2 metabolism, as well as fat metabolism and steroid hormone production.
Responsible for about 75% of drug metabolism, often making compounds inactive or sometimes activating them.
Factors that influence CYP activity: genetic variations, age, gender, and health status.
Drug interactions can occur when drugs alter CYP activity, leading to potential adverse effects (example: erythromycin and mevastatin interaction).

Types and Families of CYP

Two main types: mitochondrial (inactivating O2) and microsomal (metabolizing xenobiotics).
Humans possess 57 CYP genes categorized into 18 families and 43 sub-families, indicating diverse metabolic capabilities.
CYP nomenclature involves the abbreviation CYP followed by gene family and subfamily indicators (e.g., CYP1A1).
Most CYPs are inducible, meaning their production increases in response to the presence of xenobiotics.

Obesity

Obesity is characterized by excessive body fat accumulation due to energy intake exceeding energy expenditure.
Diagnosis primarily involves calculating Body Mass Index (BMI) and assessing for related health issues, such as hypertension and diabetes.
Treatment plans typically aim for a 5% to 10% weight loss, focusing on dietary changes and increased physical activity.
Diet should emphasize reducing caloric intake (1,200-1,800 calories/day), opting for nutrient-rich plant foods, lean proteins, and limiting sugars and fats.
Exercise recommendations include at least 150 minutes of moderate physical activity weekly to support weight maintenance and loss.
Medications may be prescribed to complement dietary and exercise efforts.

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Description

Test your knowledge on the metabolism of xenobiotics with this quiz. Learn about the different types of xenobiotics, including drugs and insecticides, and how the body processes these foreign compounds. Explore mechanisms like redistribution and excretion crucial for understanding biotransformation.