Q.60 What is the major secondary metabolite present in Clove buds?
1. Thymol
2. Eugenol
3. Zingiberine
4. Piperine
Bryophytes were unique for their gametophyte dominance, but in medicinal botany, clove buds stand out for their rich secondary metabolites. These compounds, like essential oils, give cloves their signature aroma and health benefits, making them a frequent NEET topic in plant physiology and pharmacognosy.
Clove (Syzygium aromaticum) flower buds yield 15-20% essential oil, dominated by phenolic compounds that act as antioxidants and antimicrobials.
Correct Answer: Option 2 – Eugenol
The major secondary metabolite in clove buds is eugenol.
Eugenol (4-allyl-2-methoxyphenol) comprises 70-90% of clove bud oil, alongside minor eugenyl acetate (10-15%) and β-caryophyllene (5-12%). This volatile phenylpropanoid provides clove’s spicy scent and drives its uses in dentistry (analgesic), perfumery, and as a natural preservative. In exams, recognize it as the chief bioactive from unopened Syzygium aromaticum buds.
Option Analysis Table
| Option | Source Plant/Role | Present in Clove Buds? | Why Incorrect/Correct? |
|---|---|---|---|
| 1. Thymol | Thyme, oregano (antiseptic monoterpenoid) | Minor trace | Not major; <1% in clove oil |
| 2. Eugenol | Clove buds (primary phenolic oil) | Yes, 70-90% | Dominant metabolite |
| 3. Zingiberine | Ginger rhizomes (sesquiterpene) | No | Ginger-specific, absent in clove |
| 4. Piperine | Black pepper fruits (alkaloid) | No | Piper nigrum compound, not clove |
Thymol appears in trace phenylpropanoids but never dominates clove oil. Zingiberine and piperine belong to unrelated spices, testing your plant-specific metabolite recall.
Clove Metabolites in Context
Secondary metabolites like eugenol evolved for defense against microbes and herbivores, aiding clove’s tropical survival. Extraction via steam distillation yields oil used in Ayurveda for toothaches and inflammation—eugenol inhibits COX enzymes like aspirin.
For NEET prep, link this to economic botany: clove as Myrtaceae family cash crop from India/Indonesia. Compare with cinnamon (cinnamaldehyde) or turmeric (curcumin) for pattern recognition.
