Flavonoids – Tea MCQs With Answer

Flavonoids – Tea MCQs With Answer

Flavonoids are plant polyphenols central to tea pharmacognosy, influencing antioxidant activity, astringency, and therapeutic potential. In tea, catechins (especially EGCG), flavonols, theaflavins and thearubigins vary with processing (green vs. black tea), affecting stability, bioavailability, metabolism (glucuronidation, methylation), and pharmacological effects such as cardioprotection and anti-inflammatory action. Analytical techniques—HPLC, UPLC-MS, UV, and colorimetric assays—are key for quantification and quality control. Understanding structure–activity relationships, extraction parameters, and drug–polyphenol interactions is essential for B.Pharm students preparing for examinations and practicals. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which flavonoid subclass is most abundant in green tea?

• Anthocyanins
• Catechins
• Isoflavones
• Flavones

Correct Answer: Catechins

Q2. Which catechin is considered the most pharmacologically active and abundant in green tea?

• Epicatechin (EC)
• Epigallocatechin gallate (EGCG)
• Epigallocatechin (EGC)
• Epicatechin gallate (ECG)

Correct Answer: Epigallocatechin gallate (EGCG)

Q3. During black tea production, which process converts catechins into theaflavins and thearubigins?

• Fermentation (oxidation)
• Decoction
• Freeze-drying
• Steam sterilization

Correct Answer: Fermentation (oxidation)

Q4. Which analytical technique is most commonly used for separation and quantification of individual tea flavonoids?

• Gas chromatography with FID
• High-performance liquid chromatography (HPLC)
• Thin-layer chromatography (TLC) only
• FTIR spectroscopy

Correct Answer: High-performance liquid chromatography (HPLC)

Q5. Which structural feature primarily distinguishes flavonols from flavones?

• Presence of a 3-hydroxyl group on the C-ring
• Double bond between C2 and C3
• Galloyl ester at 3-position
• Glycosylation at 7-position

Correct Answer: Presence of a 3-hydroxyl group on the C-ring

Q6. Which in vitro assay measures radical scavenging activity commonly used for tea flavonoids?

• MIC assay
• DPPH assay
• ELISA
• Agar diffusion

Correct Answer: DPPH assay

Q7. Which metabolic pathway is most important for the biotransformation of tea catechins in humans?

• Nitrosation
• Glucuronidation and sulfation
• Carboxylation
• Deamination

Correct Answer: Glucuronidation and sulfation

Q8. What effect does milk addition have on tea flavonoid bioactivity in many studies?

• Enhances absorption significantly
• Forms complexes with proteins, potentially reducing bioavailability
• Converts catechins into theaflavins
• Completely degrades flavonoids

Correct Answer: Forms complexes with proteins, potentially reducing bioavailability

Q9. Which of the following is a major pro-oxidant risk when high concentrations of tea flavonoids are used in vitro?

• Generation of hydrogen peroxide and metal-catalyzed oxidation
• Glycation of proteins
• Formation of disulfide bonds
• Excessive ATP production

Correct Answer: Generation of hydrogen peroxide and metal-catalyzed oxidation

Q10. Which compound is a galloylated catechin found in tea that influences potency and astringency?

• Quercetin
• EGCG (Epigallocatechin gallate)
• Kaempferol
• Theaflavin

Correct Answer: EGCG (Epigallocatechin gallate)

Q11. Which pH and temperature condition tends to degrade catechins fastest during extraction?

• Acidic pH at low temperature
• Neutral pH at room temperature
• Alkaline pH and high temperature
• Freezing conditions

Correct Answer: Alkaline pH and high temperature

Q12. Theaflavins are dimers formed by oxidative coupling of which molecules?

• Flavonols and isoflavones
• Two catechin molecules
• Anthocyanins and tannins
• Flavones and carotenoids

Correct Answer: Two catechin molecules

Q13. Which flavonoid subclass in tea contributes most to color changes during black tea production?

• Flavonols
• Theaflavins and thearubigins
• Isoflavones
• Anthoxanthins

Correct Answer: Theaflavins and thearubigins

Q14. Which chromatographic detector is useful for specific mass identification of flavonoids in tea?

• Refractive index detector
• Mass spectrometer (MS) detector
• Flame ionization detector
• Thermal conductivity detector

Correct Answer: Mass spectrometer (MS) detector

Q15. Which flavonoid-related parameter is most important for standardization of herbal tea extracts?

• Total protein content
• Content of marker flavonoid(s) (e.g., EGCG)
• Chlorophyll concentration
• Mineral ash value

Correct Answer: Content of marker flavonoid(s) (e.g., EGCG)

Q16. Which modification increases water solubility and often occurs during phase II metabolism of flavonoids?

• Methylation at aromatic ring
• Glucuronidation
• Hydrogenation of the C2–C3 bond
• Carboxylation to form amino acids

Correct Answer: Glucuronidation

Q17. Which tea processing step is minimized to retain maximal catechin content?

• Withering
• Rolling
• Oxidation (fermentation)
• Drying

Correct Answer: Oxidation (fermentation)

Q18. Which cofactor or metal ion can catalyze catechin oxidation and influence assay results?

• Sodium ion
• Iron (Fe2+/Fe3+)
• Potassium ion
• Magnesium ion only

Correct Answer: Iron (Fe2+/Fe3+)

Q19. In pharmacokinetic terms, which factor primarily limits systemic exposure of intact catechins after oral ingestion?

• High passive permeability across intestinal epithelium
• Extensive first-pass metabolism and conjugation
• Complete stomach absorption with no metabolism
• Active transport into red blood cells

Correct Answer: Extensive first-pass metabolism and conjugation

Q20. Which standard assay estimates total phenolic content often used in tea analysis?

• Bradford assay
• Folin–Ciocalteu assay
• Kjeldahl method
• Lowry assay

Correct Answer: Folin–Ciocalteu assay

Q21. Which structural change increases lipophilicity of catechins and may affect tissue distribution?

• Glucuronidation
• Galloylation (addition of galloyl group)
• Sulfation
• Conjugation with glucuronic acid

Correct Answer: Galloylation (addition of galloyl group)

Q22. Which tea-derived compound class has been implicated in modulating gut microbiota?

• Theaflavins and catechins
• Alkaloids only
• Sugars and starches
• Proteins

Correct Answer: Theaflavins and catechins

Q23. Which analytical parameter is critical when developing an HPLC method for catechin separation?

• Column temperature, mobile phase composition, and gradient
• Sample luminosity only
• Evaporation rate of solvent in room air
• Ambient light color

Correct Answer: Column temperature, mobile phase composition, and gradient

Q24. Which interaction is most relevant for possible drug–tea flavonoid interactions in the intestine?

• Chelation of glucose
• Inhibition or induction of intestinal transporters and phase II enzymes
• Direct covalent binding to DNA in enterocytes
• Increasing gastric pH only

Correct Answer: Inhibition or induction of intestinal transporters and phase II enzymes

Q25. Which peak assignment technique helps confirm flavonoid structures after HPLC separation?

• UV spectral matching and MS fragmentation patterns
• Measuring refractive index alone
• Smell comparison
• Counting retention time in seconds only

Correct Answer: UV spectral matching and MS fragmentation patterns

Q26. Which of the following best describes thearubigins?

• Simple monomeric flavonoids with known structures
• Complex, polymeric oxidation products of catechins contributing to color and taste
• An alkaloid class unrelated to polyphenols
• Pure carbohydrate polymers

Correct Answer: Complex, polymeric oxidation products of catechins contributing to color and taste

Q27. Which flavonoid-related test can estimate antioxidant capacity by peroxyl radical scavenging?

• ORAC assay
• Minimum inhibitory concentration
• pH titration
• Melting point determination

Correct Answer: ORAC assay

Q28. Which processing factor increases flavonol glycoside extraction from tea leaves during brewing?

• Short, cold infusion only
• Longer infusion time and higher temperature
• Use of nonpolar solvents only
• Immediate freezing of brew

Correct Answer: Longer infusion time and higher temperature

Q29. Which adverse effect has been occasionally reported with high-dose green tea extract supplements?

• Hepatotoxicity
• Renal stone formation due to oxalate
• Severe hyperglycemia in all users
• Permanent hair loss

Correct Answer: Hepatotoxicity

Q30. For quality control of tea flavonoid preparations, which parameter is most directly indicative of batch-to-batch consistency?

• Total ash value only
• Assay of marker flavonoid content and chromatographic fingerprinting
• Smell intensity measured by panel
• Packaging color

Correct Answer: Assay of marker flavonoid content and chromatographic fingerprinting

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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