Antifungal activity of methylxanthines based on their properties

Abstract

Wood materials for construction purposes can be attacked by various wood-destroying fungi. An ideal wood-preserving substance is supposed to be environment- and health-friendly. For this reason, the effects of the most relevant and non-toxic methylxanthines, such as caffeine and its metabolites theobromine and theophylline, on fungal growth, together with their degradability related to their properties were analyzed in this study. Agar tests with four wood-destroying fungal species (Serpula lacrymans, Coniophora puteana, Gleophyllum sepiarium, and Trametes versicolor) were performed after 28 days of substance exposure. Caffeine exhibited a 100% inhibitive effect on fungal growth, contrary to theobromine, which was not effective in that respect. Theophylline exhibited variable effects on the analyzed fungi. The analysis of degradability indicated the persistence of caffeine and theobromine, but theophylline was degraded up to 34%. The relation of toxicity to chemical structure of studied methylxanthines indicated the dipole moment and lipophilicity as important parameters affecting the antifungal properties. Both caffeine and theophylline are suitable potential candidates for antifungal active substances.

Antifungal Activity of Methylxanthines against Grapevine Trunk Diseases

“…and mechanistic insights revealed that it induces membrane damage due to enhanced ionic disturbances and depleted ergosterol levels with a concomitant rise in membrane fluidity due to elevated flippase activity. Regarding the differences in toxicity for fungi among the two methylxanthines, this would result from differences in the dipole moment, lipophilicity, and solubility, as noted by Kobetičová et al [5]. Caffeine is more lipophilic, which correlates with its easier penetration of membranes and possible toxic effects on fungi.…”

“…and Phoma violacea (Bertel) Eveleigh. Kobetičová et al [5] tested the activity of both caffeine and theophylline at a concentration of 2000 µg mL −1 against Coniophora puteana (Schumach.) P.…”

“…On the other hand, methylxanthines feature an interesting antifungal activity, given that they inhibit fungal chitinases that are necessary for fungal cell wall remodeling and cell replication [3]. In fact, several studies have put forward caffeine-and more recently, theophylline-as ecological, safe, and affordable alternatives to conventional biocides for wood protection [4][5][6][7].…”

Antifungal Agents in Wood Protection—A Review

“…globosum ), wood-staining fungi ( A. pullulans and S. pythiophila ), and molds ( A. niger , A. terreus , C. herbarum , P. variotii , P. cyclopium , P. funiculosum , P. brevicompactum , P. violacea , and T. viride ) [ 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. Kobetičová et al [ 46 ] assessed the effect of non-toxic methylxanthines including caffeine and its metabolites—theobromine and theophylline on the growth of four wood-destroying fungal species ( S. lacrymans , C. puteana , G. sepiarium , and T. versicolor ) in the agar test. The results indicated that caffeine exhibited a 100% inhibitory effect on all fungal strains, in contrast to theobromine, which was not effective in this regard.…”

Efficacy of Caffeine Treatment for Wood Protection—Influence of Wood and Fungi Species

“…Lightly permeable types of pine and beech wood and the method of vacuum impregnation [7,11,12] were used in most cases, but efficiency on hard-to-permeate spruce wood was also verified using long-term dipping technology [13]. Caffeine was effective against the growth of wood-destroying white and brown rot fungi [6][7][8]10,12,14] and was also tested on wooden specimens for mould growth [15]. So far, a 2% caffeine solution was tested as an effective concentration, whereas tests using lower concentrations that would reduce the cost of the used protection [1,16] are lacking.…”