Composition analysis of exudates produced by conifers grown in Taiwan and their antifungal activity

Abstract

Exudates are involved in the defense mechanism of trees; they could work against insects or microorganisms through a physical or chemical system. The main components of exudates are terpenoids. This study identified the main compounds of exudates from 13 conifers of Taiwan using gas chromatogram–mass spectrometry (GC–MS) and spectroscopic analysis. The results revealed that the main volatiles were α-pinene, β-ocimene, β-pinene, sabinene, and caryophyllene. On the other hand, the main nonvolatile compounds were diterpenoids, which were classified into three skeletons (abietane-, labdane-, and pimarane-types). Among these, abietane-type presented in Pinaceae and in most of Cupressaceae; labdane-type presented in Pinaceae and in all of Cupressaceae and Araucariaceae; pimarane-type existed in both Pinaceae and Cupressaceae. Furthermore, the epigenetics of conifers analysis results by GC–MS and heteronuclear single quantum coherence (HSQC) of nuclear magnetic resonance (NMR) fingerprints were similar to traditional taxonomy classification; it indicated that exudates chemotaxonomy by using GC–MS and HSQC profiling is a useful technology to classify the conifers. Besides, the exudates of Pinus elliottii, Pinus taiwanensis, Calocedrus macrolepis and Chamaecyparis formosensis possessed the strong antifungal activity. For white-rot fungus, Trametes versicolor, Pinus morrisonicola, Chamaecyparis obtusa, and Araucaria heterophylla exhibited the higher antifungal index. For brown-rot fungus, Laetiporus sulphureus, Pinus elliottii, Pinus morrisonicola, and Chamaecyparis formosensis revealed a good antifungal activity.