Herbal hair colorants MCQs With Answer

Herbal hair colorants MCQs With Answer

This quiz collection is designed for M. Pharm students studying Herbal Cosmetics (MPG 204T). It focuses on the chemistry, sources, dyeing mechanisms, formulation considerations, quality control and safety aspects of herbal hair colorants such as henna, indigo, cassia, madder and turmeric. Questions emphasize molecular dye-fiber interactions, extraction and analytical techniques, role of mordants and pre/post-treatment of hair, stability and fastness behaviour, and common adverse reactions. The set aims to deepen conceptual understanding and prepare students for applied formulation, regulatory and research tasks in herbal hair dye development and evaluation.

Q1. Which compound is the primary coloring principle in henna (Lawsonia inermis)?

• Lawsone (2-hydroxy-1,4-naphthoquinone)
• Indigo (indigotin)
• Curcumin
• Alizarin

Correct Answer: Lawsone (2-hydroxy-1,4-naphthoquinone)

Q2. What is the principal chemical mechanism by which lawsone dyes human hair keratin?

• Covalent bonding to keratin amino groups via nucleophilic addition (Michael-type)
• Ionic interaction with carboxyl groups of keratin
• Physical adsorption into the hair cortex through van der Waals forces
• Formation of metal chelates with keratin-bound minerals

Correct Answer: Covalent bonding to keratin amino groups via nucleophilic addition (Michael-type)

Q3. Indigo dyeing of hair requires which key chemical transformation before application?

• Reduction of indigo to its soluble leuco form under alkaline conditions

Correct Answer: Reduction of indigo to its soluble leuco form under alkaline conditions

Q4. Combining henna and indigo powders on hair is done primarily to achieve which outcome?

Correct Answer:

Q5. Which plant is commonly called “neutral henna” and is used to impart golden tones without lawsone?

• Cassia obovata

Correct Answer: Cassia obovata

Q6. What is the primary role of Amla (Emblica officinalis) when included in herbal hair-color formulations?

Correct Answer: Acts as a natural mordant and provides tannins that enhance dye uptake and conditioning

Q7. Which metal salt is commonly used to darken natural dye shades but may also risk hair damage if misused?

Correct Answer:

Q8. Alizarin, an anthraquinone red dye used in herbal colorants, is primarily obtained from which botanical source?

Correct Answer:

Q9. Why do turmeric (curcumin)-based hair colorants generally show poor color fastness?

Correct Answer:

Q10. Which solvent is commonly employed for quantitative extraction of lawsone for HPLC/HPTLC analysis?

Correct Answer: Methanol (or methanol-water mixtures)

Q11. Increasing the pH of a henna paste generally affects dye uptake by hair how?

Correct Answer: Alkaline pH increases nucleophilicity of keratin amino groups and enhances color uptake

Q12. What is the recommended pre-treatment of hair before applying a powdered herbal dye paste to maximize even coloration?

Correct Answer: Cleanse to remove oils and residues, then towel-dry to slightly damp condition

Q13. Which analytical technique is most widely used for quantitative determination of lawsone in raw henna material and formulations?

Correct Answer: HPLC (High Performance Liquid Chromatography)

Q14. How is henna classified in dye terminology with respect to hair fibers?

Correct Answer: Substantive (direct) dye that binds directly to keratin

Q15. Which chemical is most frequently responsible for allergic contact dermatitis associated with “black henna” applications?

Correct Answer:

Q16. For commercial herbal hair colorants containing aqueous plant extracts, which excipient addition is essential to ensure product safety during shelf life?

Correct Answer: Effective preservative system to control microbial growth

Q17. Which in vitro test is most relevant to assess the practical durability of color on hair after consumer use?

Correct Answer: Wash fastness test (repeated shampooing cycles)

Q18. Indigo for hair dye is traditionally obtained from which botanical species?

Correct Answer: Indigofera tinctoria

Q19. What is the primary function of alum (potassium aluminum sulfate) when used in herbal hair dye formulations?

Correct Answer: Acts as a mordant to bind dye molecules to hair and improve shade brightness

Q20. Which set of quality tests should a manufacturer routinely perform on finished herbal hair colorant products before release?

Correct Answer: Microbial limits, heavy metal analysis, and assay of active dye content

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