4.5 Oxidative polymerization of sesquiterpenes

Oxidative Polymerization of Sesquiterpenes in Agarwood – How Aquilaria Converts Defense Metabolites into High-Value Resin

Agarwood resin is not just liquid sap—it is a complex polymerized mixture of sesquiterpenes and chromones. Oxidative polymerization is the key biochemical process that transforms defense metabolites into aromatic, resinous agarwood.

1. What Are Sesquiterpenes?

  • Sesquiterpenes are C15 terpenoids produced by Aquilaria as part of its defense response.
  • Produced in response to:
    • Biotic stress: Fusarium or fungal colonization (FusaPrime™, Harmonia™)
    • Abiotic stress: Wounding, chemical elicitors (AgarStart™, ResinRush™)
  • Serve as precursors for resin formation, eventually polymerizing to form dense aromatic compounds.

2. Oxidative Polymerization: The Process

Definition: The chemical transformation of monomeric sesquiterpenes into larger polymerized compounds through oxidation.

Mechanism:

  1. ROS Generation – Reactive oxygen species (H₂O₂, superoxide) produced via oxidative priming
  2. Enzymatic Activation – Tree enzymes (peroxidases, oxidases) catalyze sesquiterpene oxidation
  3. Polymer Formation – Monomers link into longer-chain molecules, creating:
    • Dark, viscous resin
    • Aromatic, stable compounds (chromones + sesquiterpene polymers)
  4. Resin Deposition – Polymerized sesquiterpenes accumulate in xylem around inoculation points

BarIno™ Insight:

  • Controlled ROS via AgarStart™ and oxidative priming ensures polymerization without harming cambium.
  • Biotic induction provides precursors and triggers for efficient polymerization.

3. Factors Affecting Oxidative Polymerization

FactorEffect
Sap flow & cambium vitalityEnsures metabolite transport and active enzymatic reactions
Tree stress (abiotic & biotic)Triggers ROS bursts and enzyme activation
Seasonal conditionsDry season favors polymer stability; wet season promotes precursor formation
Inoculation density & depthOptimizes localized metabolite concentration for polymerization
BarIno™ sequencingSequential induction ensures staged polymerization and densification

4. Visual / Sensory Indicators

  • Resin darkening: yellow → brown → black
  • Increased viscosity: thick, sticky sap around wounds
  • Aroma intensification: sweet, woody, spicy notes
  • Resin is harder and more compact after polymerization

Early resin may be semi-liquid; oxidative polymerization over weeks to months locks it into aromatic, high-value agarwood.

5. BarIno™ Sequential Strategy for Polymerization

  1. AgarStart™ – triggers ROS and oxidative priming
  2. FusaPrime™ – provides biotic metabolites and enzymatic triggers
  3. FusaTrinity™ / Harmonia™ – amplifies stress and defense response
  4. FusaBlaze™ / ResinRush™ – ensures dense resin deposition and final polymerization

Key Insight:

Oxidative polymerization is the chemical “locking step” that converts tree defense metabolites into commercially valuable agarwood resin.

6. Farmer-Friendly Summary

  • Sesquiterpenes = “raw resin ingredients”
  • ROS and oxidative priming = “catalyst”
  • Polymerization = “resin solidification and aroma development”
  • Sequential BarIno™ application = controlled process for maximum yield and quality