Role of free radicals in Inflammation MCQs With Answer

Free radicals and oxidative stress are central drivers of inflammation and its progression to chronic disease. For B. Pharm students, understanding reactive oxygen species (ROS), reactive nitrogen species (RNS), sources, and antioxidant defenses is essential for pharmacology and drug development. Free radical–mediated lipid peroxidation, protein and DNA damage activate signaling pathways such as NF-κB and MAPK, promoting cytokine release and sustained inflammatory responses. Evaluating biomarkers (MDA, 8‑OHdG), assays, and pharmacologic modulators (antioxidants like N‑acetylcysteine, vitamin E; enzyme systems SOD, catalase) connects theory to therapeutics. This focused overview prepares you to analyze mechanisms, interpret lab data, and consider antioxidant strategies in treatment. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which species is commonly classified as a primary reactive oxygen species implicated in initiating inflammation?

• Hydroxyl radical (•OH)
• Peroxynitrite (ONOO−)
• Superoxide anion (O2•−)
• Nitric oxide (NO)

Correct Answer: Superoxide anion (O2•−)

Q2. Lipid peroxidation in cell membranes primarily produces which biomarker used to assess oxidative damage?

• 8‑OHdG
• Malondialdehyde (MDA)
• C-reactive protein (CRP)
• Glutathione (GSH)

Correct Answer: Malondialdehyde (MDA)

Q3. Which enzyme catalyzes the dismutation of superoxide into hydrogen peroxide and oxygen?

• Catalase
• Glutathione peroxidase
• Superoxide dismutase (SOD)
• NADPH oxidase

Correct Answer: Superoxide dismutase (SOD)

Q4. Peroxynitrite (ONOO−) forms from the reaction between which two radicals?

• Superoxide and hydroxyl radical
• Nitric oxide and superoxide
• Hydrogen peroxide and iron
• Nitric oxide and hydrogen peroxide

Correct Answer: Nitric oxide and superoxide

Q5. Activation of NF-κB by ROS most directly leads to increased expression of which mediators?

• Antioxidant enzymes only
• Pro-inflammatory cytokines like TNF-α and IL-6
• Mitochondrial DNA repair enzymes
• Membrane phospholipids

Correct Answer: Pro-inflammatory cytokines like TNF-α and IL-6

Q6. Which intracellular antioxidant directly reduces hydrogen peroxide to water using glutathione as a cofactor?

• Catalase
• Glutathione peroxidase (GPx)
• Thioredoxin reductase
• Superoxide dismutase

Correct Answer: Glutathione peroxidase (GPx)

Q7. Chronic inflammation mediated by oxidative stress contributes to atherogenesis primarily via which mechanism?

• Direct inhibition of platelet aggregation
• Oxidation of LDL and endothelial dysfunction
• Increased hepatic cholesterol synthesis
• Suppression of macrophage activation

Correct Answer: Oxidation of LDL and endothelial dysfunction

Q8. Which assay is commonly used to estimate total antioxidant capacity by measuring reduction of a stable free radical?

• TBA/TBARS assay
• DPPH radical scavenging assay
• ELISA for cytokines
• Western blot for SOD

Correct Answer: DPPH radical scavenging assay

Q9. Which non-enzymatic antioxidant acts primarily by donating a hydrogen atom to lipid peroxyl radicals, protecting membranes?

• Vitamin C (ascorbate)
• Vitamin E (alpha-tocopherol)
• Selenium
• Uric acid

Correct Answer: Vitamin E (alpha-tocopherol)

Q10. In drug-induced oxidative stress, which organ is most susceptible due to high P450 activity and abundance of mitochondria?

• Heart
• Liver
• Skin
• Bone marrow

Correct Answer: Liver

Q11. 8‑OHdG is a biomarker for oxidative damage to which macromolecule?

• Lipids
• Proteins
• Carbohydrates
• DNA

Correct Answer: DNA

Q12. NADPH oxidase in phagocytes generates ROS primarily to:

• Signal DNA repair mechanisms
• Mediate microbial killing during respiratory burst
• Promote mitochondrial ATP synthesis
• Activate adaptive immunity directly

Correct Answer: Mediate microbial killing during respiratory burst

Q13. Which pharmacologic agent replenishes intracellular glutathione by supplying cysteine and is used as an antioxidant therapy?

• Vitamin E
• N-acetylcysteine (NAC)
• Selenium yeast
• Ibuprofen

Correct Answer: N-acetylcysteine (NAC)

Q14. Oxidative modification of which protein in endothelial cells reduces nitric oxide bioavailability, promoting vasoconstriction and inflammation?

• Endothelin
• eNOS (endothelial nitric oxide synthase)
• Albumin
• Fibrinogen

Correct Answer: eNOS (endothelial nitric oxide synthase)

Q15. Which pathway senses oxidative stress and upregulates phase II antioxidant enzymes via the antioxidant response element (ARE)?

• NF-κB pathway
• PI3K-Akt pathway
• Keap1-Nrf2 pathway
• JAK-STAT pathway

Correct Answer: Keap1-Nrf2 pathway

Q16. Which reactive species is generated by Fenton chemistry and is highly reactive toward DNA, proteins, and lipids?

• Hydroxyl radical (•OH)
• Hydrogen peroxide (H2O2)
• Superoxide anion (O2•−)
• Nitric oxide (NO)

Correct Answer: Hydroxyl radical (•OH)

Q17. Measuring thiobarbituric acid reactive substances (TBARS) primarily estimates levels of:

• Protein carbonyls
• Lipid peroxidation products such as MDA
• Reduced glutathione concentration
• Antioxidant enzyme activity

Correct Answer: Lipid peroxidation products such as MDA

Q18. Which cytokine is both induced by ROS and can itself increase ROS production in a feed-forward loop during inflammation?

• Interleukin-10 (IL-10)
• Transforming growth factor-beta (TGF-β)
• Tumor necrosis factor-alpha (TNF-α)
• Interferon-beta (IFN-β)

Correct Answer: Tumor necrosis factor-alpha (TNF-α)

Q19. Which antioxidant enzyme converts hydrogen peroxide into water and oxygen, primarily found in peroxisomes?

• Glutathione reductase
• Catalase
• Superoxide dismutase
• Myeloperoxidase

Correct Answer: Catalase

Q20. Excessive ROS can cause activation of inflammasomes; which inflammasome is most often associated with sterile inflammation driven by damage signals?

• NLRP3 inflammasome
• AIM2 inflammasome
• NLRC4 inflammasome
• RIG-I inflammasome

Correct Answer: NLRP3 inflammasome

Q21. Which nutritional antioxidant can regenerate the reduced form of vitamin E and is important in aqueous cellular compartments?

• Vitamin A
• Vitamin C (ascorbate)
• Beta-carotene
• Coenzyme Q10

Correct Answer: Vitamin C (ascorbate)

Q22. In the context of inflammation, oxidative damage to mitochondrial DNA primarily leads to:

• Enhanced antioxidative capacity
• Increased mitochondrial ROS production and dysfunction
• Rapid repair and immediate cell proliferation
• Sequestration of cytokines

Correct Answer: Increased mitochondrial ROS production and dysfunction

Q23. Which drug class can indirectly reduce ROS-mediated inflammation by inhibiting COX enzymes and prostaglandin synthesis?

• Statins
• Proton pump inhibitors
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Beta-blockers

Correct Answer: Nonsteroidal anti-inflammatory drugs (NSAIDs)

Q24. Protein carbonylation is an oxidative modification affecting which amino acid side chains most commonly?

• Glycine and alanine
• Lysine, arginine, proline, and threonine
• Methionine and cysteine only
• Tryptophan exclusively

Correct Answer: Lysine, arginine, proline, and threonine

Q25. Which laboratory technique quantifies 8‑OHdG as a marker of oxidative DNA damage with high specificity?

• Colorimetric TBARS
• High-performance liquid chromatography with electrochemical detection (HPLC-ECD)
• Light microscopy
• Standard PCR without modification

Correct Answer: High-performance liquid chromatography with electrochemical detection (HPLC-ECD)

Q26. Selenium is a cofactor for which antioxidant enzyme relevant to inflammation control?

• Superoxide dismutase
• Glutathione peroxidase (GPx)
• Catalase
• NADPH oxidase

Correct Answer: Glutathione peroxidase (GPx)

Q27. Which of the following best describes redox signaling in inflammatory responses?

• Irreversible oxidative damage only
• ROS serve solely as toxic byproducts with no signaling role
• Controlled ROS levels act as second messengers modifying proteins and transcription factors
• Antioxidants always inhibit necessary immune signaling

Correct Answer: Controlled ROS levels act as second messengers modifying proteins and transcription factors

Q28. Which mitochondrial complex is a major site of superoxide generation during dysfunction?

• Complex I and III of the electron transport chain
• Complex II exclusively
• ATP synthase only
• Succinate dehydrogenase exclusively

Correct Answer: Complex I and III of the electron transport chain

Q29. Which therapeutic approach specifically targets oxidative stress by supplying catalytic mimetics of antioxidant enzymes?

• Small-molecule SOD mimetics
• Monoclonal antibodies against cytokines
• Proton pump inhibitors
• ACE inhibitors

Correct Answer: Small-molecule SOD mimetics

Q30. In evaluating anti-inflammatory drug candidates, which in vitro assay would help assess antioxidant potential by measuring inhibition of lipid peroxidation?

• MTT cell viability assay
• TBARS assay measuring MDA formation
• ELISA for TNF-α only
• Gram staining

Correct Answer: TBARS assay measuring MDA formation

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