Isolation of sennosides from Senna is a key topic for B. Pharm students studying phytochemical extraction, analysis, and standardization. Sennosides (notably sennoside A and sennoside B) are dianthrone anthraquinone glycosides present in Senna (Senna alexandrina/Cassia angustifolia) with stimulant laxative activity produced after microbial conversion to rhein anthrone. Practical isolation combines defatting, hydroalcoholic extraction, controlled acid or enzymatic hydrolysis, and chromatographic purification (TLC, preparative HPLC, C18 columns). Quality control emphasizes stability, pH sensitivity, proper drying, and use of reference standards. This concise review links chemistry, extraction techniques, and analytical methods for reliable quantification. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the chemical class of sennosides found in Senna?
- Dianthrone (anthraquinone) glycosides
- Flavonoid glycosides
- Tannin polymers
- Alkaloid glycosides
Correct Answer: Dianthrone (anthraquinone) glycosides
Q2. Which two sennosides are the major constituents commonly quantified in Senna extracts?
- Sennoside A and Sennoside B
- Sennoside C and Sennoside D
- Emodin and Chrysophanol
- Aloe-emodin and Rhein
Correct Answer: Sennoside A and Sennoside B
Q3. What is the primary botanical source used for commercial sennoside production?
- Senna alexandrina (Cassia angustifolia)
- Aloe vera
- Rhubarb (Rheum officinale)
- Berberis vulgaris
Correct Answer: Senna alexandrina (Cassia angustifolia)
Q4. Which active metabolite is produced from sennosides by intestinal bacteria and mediates the laxative effect?
- Rhein anthrone (rheinanthrone)
- Emodin
- Aloe-emodin
- Chrysophanol
Correct Answer: Rhein anthrone (rheinanthrone)
Q5. Which solvent system is most suitable for the initial extraction of sennosides from powdered Senna leaves?
- Hydroalcoholic solvent (methanol-water)
- Pure hexane
- Chloroform
- Petroleum ether
Correct Answer: Hydroalcoholic solvent (methanol-water)
Q6. Which extraction technique gives exhaustive extraction but may risk thermal degradation of sennosides?
- Soxhlet extraction
- Maceration at room temperature
- Cold percolation
- Ultrasound-assisted extraction at low temperature
Correct Answer: Soxhlet extraction
Q7. In the laboratory, which hydrolysis method is commonly used to release anthraquinone aglycones from sennosides for analysis?
- Acid hydrolysis under controlled conditions
- Strong alkaline hydrolysis without pH control
- Dry heating at high temperature
- Chlorination
Correct Answer: Acid hydrolysis under controlled conditions
Q8. Which qualitative test is used to detect anthraquinone aglycones after hydrolysis of sennosides?
- Bornträger’s test (alkaline, red color)
- Biuret test
- Froth test
- Kedde’s test
Correct Answer: Bornträger’s test (alkaline, red color)
Q9. Which HPLC stationary phase is most commonly used for analytical separation of sennosides?
- Reversed-phase C18 column
- Normal-phase silica gel
- Ion-exchange (strong anion)
- Size-exclusion (Sephadex G-25)
Correct Answer: Reversed-phase C18 column
Q10. What type of detector is routinely used for quantitative HPLC analysis of sennosides?
- UV (PDA) detector
- Refractive index detector
- Electrochemical detector
- Fluorescence detector
Correct Answer: UV (PDA) detector
Q11. Which mobile phase modifier is commonly added to improve peak shape and reproducibility for sennoside HPLC methods?
- 0.1% formic acid
- 10% sodium hydroxide
- Pyridine base
- Concentrated hydrochloric acid
Correct Answer: 0.1% formic acid
Q12. Which reference standard is frequently used for calibration in sennoside assays?
- Sennoside B reference standard
- Quercetin reference standard
- Chlorogenic acid standard
- Emodin standard
Correct Answer: Sennoside B reference standard
Q13. Why is a defatting step with hexane or petroleum ether often performed before extracting sennosides?
- To remove lipids and waxes that interfere with extraction
- To hydrolyze glycosides
- To precipitate sennosides as salts
- To sterilize the plant material
Correct Answer: To remove lipids and waxes that interfere with extraction
Q14. What is the advantage of concentrating extracts under reduced pressure (rotary evaporation) when isolating sennosides?
- Prevents thermal degradation by lowering boiling point
- Increases pH to stabilize sennosides
- Removes sugars selectively
- Converts glycosides to aglycones
Correct Answer: Prevents thermal degradation by lowering boiling point
Q15. How is identity of sennosides commonly confirmed during TLC analysis?
- Matching Rf values and color reaction with an authentic standard after hydrolysis
- By flame test
- By measuring refractive index of spot
- By melting point of TLC plate
Correct Answer: Matching Rf values and color reaction with an authentic standard after hydrolysis
Q16. Which technique is preferred for obtaining pure sennoside fractions for structural or pharmacological studies?
- Preparative HPLC
- Simple gravity filtration
- Steam distillation
- Crystallization from hexane only
Correct Answer: Preparative HPLC
Q17. Which part of the Senna plant is primarily used for commercial sennoside extraction?
- Leaves (foliage)
- Roots
- Seeds
- Bark
Correct Answer: Leaves (foliage)
Q18. Why is strict pH control important during extraction and processing of sennosides?
- To prevent acid- or base-catalyzed hydrolysis and degradation
- To induce oxidation of sennosides
- To complex sennosides with metal ions
- To increase lipid solubility
Correct Answer: To prevent acid- or base-catalyzed hydrolysis and degradation
Q19. What storage condition best preserves extracted sennosides and raw Senna material?
- Cool, dark, and dry place in airtight containers
- Hot and humid environment
- Direct sunlight at room temperature
- Open containers in a fume hood
Correct Answer: Cool, dark, and dry place in airtight containers
Q20. What is a likely consequence of prolonged heating of Senna extracts during extraction?
- Hydrolysis of sennosides and reduced yield
- Formation of stable glycoside complexes
- Increased sennoside concentration by condensation
- Selective removal of anthraquinone aglycones
Correct Answer: Hydrolysis of sennosides and reduced yield
Q21. Which analytical method provides the most reliable quantitative estimation of total sennosides in quality control?
- HPLC assay with reference standard
- Simple evaporation weight measurement
- Colorimetric Bornträger’s test
- Smell and taste assessment
Correct Answer: HPLC assay with reference standard
Q22. After controlled acid hydrolysis of sennosides, what class of compounds is measured for identification?
- Anthraquinone aglycones
- Flavonoid aglycones
- Terpenoid hydrocarbons
- Alkaloid bases
Correct Answer: Anthraquinone aglycones
Q23. Which sample preparation step helps increase surface area and improves sennoside extraction efficiency?
- Reducing particle size by fine powdering
- Using whole dried leaves without powdering
- Freezing intact leaves in liquid nitrogen only
- Soaking in concentrated acid for 24 hours
Correct Answer: Reducing particle size by fine powdering
Q24. Which mobile phase parameter most strongly affects retention and selectivity of sennosides in reversed-phase HPLC?
- pH of the aqueous component
- Molecular oxygen concentration
- Ambient room noise
- Color of the solvent bottle
Correct Answer: pH of the aqueous component
Q25. Which pre-chromatographic cleanup method can enrich sennosides from crude extract?
- Adsorption on a suitable resin (e.g., Diaion or similar) and elution
- Simple decantation without solvents
- Boiling with excess alkali
- Steam distillation
Correct Answer: Adsorption on a suitable resin (e.g., Diaion or similar) and elution
Q26. What chemical change is most likely when sennosides are exposed to strong alkaline conditions?
- Cleavage of glycosidic bonds leading to degradation
- Formation of more stable glycosides
- Polymerization into tannins
- Conversion to alkaloids
Correct Answer: Cleavage of glycosidic bonds leading to degradation
Q27. Which safety precaution is essential when performing acid hydrolysis during sennoside isolation?
- Work in a fume hood and use appropriate personal protective equipment
- Perform hydrolysis in open sunlight
- Neutralize acids with organic solvents immediately
- Heat acids to boiling without ventilation
Correct Answer: Work in a fume hood and use appropriate personal protective equipment
Q28. What is the primary pharmacological action of sennosides derived from Senna?
- Stimulant laxative action (increases intestinal motility)
- Antihypertensive effect
- Antibacterial activity against gram-negative bacteria
- Anticoagulant action
Correct Answer: Stimulant laxative action (increases intestinal motility)
Q29. Which method is commonly recommended in modern pharmacopoeial monographs for assay of total sennosides?
- HPLC-based assay with appropriate reference standard
- Simple titration with sodium hydroxide
- Gravimetric precipitation of sennosides
- Odor comparison with reference material
Correct Answer: HPLC-based assay with appropriate reference standard
Q30. What is the main objective of standardization and quality control of isolated sennosides in pharmaceutical products?
- To ensure consistent sennoside content and batch-to-batch quality
- To make the product smell pleasant
- To increase the color variability of formulations
- To eliminate the need for clinical testing
Correct Answer: To ensure consistent sennoside content and batch-to-batch quality
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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