MnO₂ | NaCl | FeCl₃ | MgCl₂ | Fusarium
The chemical composition of agarwood resin induced with sodium chloride (NaCl) as an inoculant shows some distinct characteristics due to the osmotic stress and salt-induced physiological responses it triggers in Aquilaria malaccensis. While not as biochemically complex as microbial inoculants, NaCl stress still stimulates resin biosynthesis pathways.
Key Chemical Constituents from NaCl-Induced Agarwood Resin:
1. 2-(2-Phenylethyl) Chromones
- Primary marker compounds of high-quality agarwood.
- Levels may be lower than biologically induced resin but still present.
- Stress-responsive metabolites triggered by dehydration and ion imbalance.
2. Sesquiterpenes
- Moderate levels of:
- α-Guaiene
- δ-Guaiene
- Selinene derivatives
- NaCl stress promotes mevalonate pathway activation, which leads to sesquiterpene production.
3. Phenolic and Benzenoid Compounds
- Vanillin, syringaldehyde, eugenol – contribute to sweet, woody notes.
- Induced through general stress-related metabolic upregulation.
4. Fatty Acids and Alcohol Derivatives
- Some oxidized fatty acid traces due to membrane degradation from salt stress.
- May influence aroma depth but also indicate tissue injury.
5. Reactive Oxygen Species (ROS)–Related Compounds
- ROS is elevated under salt stress, which leads to:
- Lipid peroxidation by-products
- Enhanced defense-related metabolite synthesis
Summary Table: Chemical Profile – NaCl vs. Other Inoculants
| Compound Type | Detected in NaCl Resin | Notes |
|---|---|---|
| Chromones | ✅ Present, moderate levels | Triggered by salt-induced stress |
| Sesquiterpenes | ✅ Present, moderate | Slightly lower than microbial methods |
| Phenolics | ✅ Vanillin, syringaldehyde | Sweet aroma notes |
| ROS Metabolites | ✅ Elevated | Linked to cell membrane stress |
| Triterpenes | ❌ Rare | Less common with chemical-only methods |
Insight:
- NaCl inoculation mimics drought/salt stress, which activates defensive metabolic pathways leading to resin formation.
- The chemical profile may lack some of the complexity of biologically induced agarwood, but it can still produce market-acceptable resin, especially in combination with enhancers like brown sugar or phytohormones.
Timeline of Agarwood Resin Development by Inoculant
| Inoculant | Week 2 | Week 4 | Week 6 | Week 8 | Week 10+ |
|---|---|---|---|---|---|
| Fusarium oxysporum | ◉◉◉ | ◉◉◉◉ | ◉◉◉◉ | ◉◉◉◉ | ◉◉◉◉ |
| FeCl₃ (Ferric Chloride) | ◉◉ | ◉◉◉ | ◉◉◉◉ | ◉◉◉◉ | ◉◉◉◉ |
| MnO₂ (Manganese Oxide) | ◯ | ◉ | ◉◉ | ◉◉◉ | ◉◉◉◉ |
| MgCl₂ (Magnesium Chl.) | ◯ | ◯ | ◉ | ◉◉ | ◉◉◉ |
| NaCl (Sodium Chloride) | ◯ | ◯ | ◯ | ◉ | ◉◉ |
Legend:
◉= Visible resin formation◯= No significant resin- More
◉s = Heavier or more developed resin response
Summary:
- Fusarium triggers early and sustained resin production.
- Ferric chloride follows closely with strong induction and dark resin.
- Magnesium and sodium chloride are much slower and produce less intense resin.
- Manganese oxide builds more gradually but yields good quality after 2+ months.