Chemical Nature of Antimicrobial Compounds

The various compounds responsible for the decay resistance of heartwood, their structures, their biosynthesis, and their chemotaxonomy are discussed in Chaps. 7 and 8. Most of the important antimicrobial compounds are phenolics, although the terpenoids may also be involved. Often the major portion of the phenolic extractives are polymeric materials (MW 500) that cannot be identified. These materials may be very important in increasing the durability of heartwood but little work has been reported. 

The extractives of related species are often similar and thus are useful for chemotaxonomy. For example, the Cupressaceae are the sole source of tropolones. On the other hand, the chemical nature of extractives may differ distinctly between closely related species or the same fungitoxic material may occur in unrelated plant families. 

The types of compounds known to be important in decay resistance are listed in Ihble 9.2.1. Each group of compounds will be discussed briefly. More detailed information has previously been published (45). 

Four lignans (conidendrin, isoolivil, pinoresinol, and matairesinol) were tested against several decay fungi (42, 43) and were generally nontoxic. Lentinus lepideus was inhibited by 1.0% of pinoresinol or matairesinol but was unaffected by the other compounds. Lignans often are produced by Picea or Pinus in response to 

Groups of extractives Classes of compounds Examples of each class 

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