FeCl₃ | MnO₂ | MgCl₂ | NaCl | Salicylic | H₂O₂
The chemical analysis of agarwood resin induced by Ferric Chloride (FeCl₃) inoculation often shows a unique profile compared to biological methods, as ferric chloride functions by inducing oxidative stress and triggering the plant’s wound defense response.
Key Chemical Components Detected in Agarwood Resin from Ferric Chloride Inoculation:
1. Chromones (Agarwood markers)
- 2-(2-phenylethyl)chromones
- Hydroxychromones
- Function as defense-related aromatic compounds.
- Ferric chloride enhances their production by stimulating ROS (Reactive Oxygen Species).
2. Sesquiterpenes (Major scent contributors)
- Guaiane-type sesquiterpenes (e.g., α-guaiene, δ-guaiene)
- Eudesmane-type sesquiterpenes
- Agarofuran and agarospirol (in some cases)
- These are biosynthesized via the mevalonate pathway during stress response.
3. Benzenoid and Phenolic Compounds
- Trace amounts of vanillin, syringaldehyde, and benzylacetone
- These impart sweet and woody notes.
4. Triterpenes and Fatty Acids (less common but possible)
- May be present as minor components in resin formed from physical-chemical stress.
GC-MS (Gas Chromatography–Mass Spectrometry) Profile Summary:
| Compound Type | Detected Compounds | Function |
|---|---|---|
| Chromones | 2-(2-phenylethyl)chromone | Resin formation, marker of agarwood |
| Sesquiterpenes | α-Guaiene, δ-Guaiene, Agarofuran | Aroma profile, antimicrobial defense |
| Phenolics | Vanillin, Syringaldehyde | Sweet and spicy notes |
| Terpenoids | Agarospirol, Jinkoh-eremol | Fragrance intensity and depth |
⚠️ Impact of Ferric Chloride on Composition:
- May increase chromone production due to oxidative damage.
- Sesquiterpene content varies based on:
- Tree age and health
- Inoculation depth and method
- Environmental conditions post-inoculation
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.