Condensed conifer tannins as antifungal agents in liquid culture

Abstract

In the last decades, many wood preservatives have been prohibited for their ecotoxicity. The present article is focusing on the conifer-derived condensed tannins as environment-friendly options for the substitution of artificial wood preservatives. Eight different tannin fractions were extracted from spruce cones, spruce barks, and pine cones. The parameters of tannin extraction, such as the methods of purification and concentration of active components in the extracts, have been investigated. The cone and bark extracts were tested for the growth inhibition of eight brown-rot fungi, three white-rot fungi, and four soft-rot fungi in liquid cultures. The cone tannins provided a more efficient fungal growth inhibition than bark tannins. Purification increased the antifungal properties of the extracts. The growth of brown-rot fungi was inhibited by the tannins already at low concentrations. However, the extracts were not effective against the white-rot or soft-rot fungi. More investigation is needed concerning the tannin source and the purification procedure of the extracts before tannins can be considered as an ecologically benign wood preservative.

Verticillium wilt caused by Verticillium dahliae in woody plants with emphasis on olive and shade trees

“…The tannin group of phenolic compounds is widespread in both constitutive protection and induced compartmentalization process. Tannins in foliage and wood are reactive pro-oxidant compounds (i.e., chemicals that induce oxidative stress, either by generating reactive oxygen species or by inhibiting antioxidant systems) that disrupt microbial metabolism (Antilla et al 2013). Additionally, it has been determined that trees with small xylem vessels have stronger ability than trees with large xylem vessels to compartmentalize infections (Eckstein et al 1979).…”

Antifungal Activity of Several Vegetable Origin Household Waste Extracts Against Wood-Decaying Fungi In Vitro

“…The quest for new wood preservatives is driven by the increasing tolerance of fungi to copper, the society´s environmental awareness and more strict regulations in chemical legislation in traditional wood preservatives. As some bio-based chemicals are known to be effective wood-decaying fungi inhibitors, such as tannins [1] and wood pyrolysis distillates [2], they have gained attention as substitutes of the traditional wood preservatives.…”

A new cis-p-coumaroyl flavonol glycoside from the inner barks of Sophora japonica L.

“…Forestry residues, such as tree barks or branches, are potential rich sources of novel biologically or pharmaceutically active substances, which are not well explored ( Liimatainen et al 2012 ;Anttila et al 2013 ;Patinha et al 2013 ;Si et al 2013 ). The investigation of such naturally bioactive compounds isolated from tree residue is a permanent attraction and challenge, which still leads to new discoveries ( Huh et al 2012 ;Smeds et al 2012 ;da Silva et al 2013 ;Dedic et al 2014 ;In et al 2014 ;Latva-Maenpaa et al 2014 ;Vek et al 2014 ).…”