*2.3.1 Stilbenes*

Stilbenes are phenolic compounds in which two phenol units are linked by twodoubly bonded carbons (**Figure 18**). Examples of stilbenes include resveratrol, pterostilbene and piceatannol shown (**Figure 20**).

### *2.3.2 Lignans*

Lignans consist of two phenol units linked by four carbons. Examples include matairesinol, secoisolariciresinol and pinoresinol (**Figure 21**).

## *2.3.3 Lignins*

Lignins consist of phenol units or phenolic compounds that are linked with each other by carbon chains (**Figure 22**). Lignins are high molecular weight polymers.

**Figure 21.** *General structure of lignans and examples.*

**Figure 22.** *A segment of lignins.*
