Unveiling the antifungal potential of extracts in leaves and branches from Nicotiana glauca for wood biofungicides

Wild-growing medicinal plants are a rich source of bioactive compounds, which serve as antimicrobial agents for various medicinal, pharmaceutical, and wood preservation uses. In this study, branches and leaves from Nicotiana glauca Graham, a wild plant from Egypt, were used to extract bioactive compounds using the ethanol solvent. The ethanol extracts (EEs) were analyzed for their chemical components using HPLC and GC-MS. The EEs were applied to Fagus sylvatica L. wood to evaluate their activity against the growth of three fungi, namely Phoma glomerata, Fusarium circinatum, and Pythium tardicrescens. By HPLC analysis, the abundant phenolic and flavonoid compounds in EE from the branches were rutin (1529.37 µg/g dry extract), quercetin (856.96 µg/g dry extract), and gallic acid (813.79 µg/g dry extract). The N. glauca leaf EE contained high amounts of rutin (23364.18 µg/g dry extract), chlorogenic acid (3136.67 µg/g dry extract), gallic acid (1133.30 µg/g dry extract), and coumaric acid (1066.13 µg/g dry extract). The GC-MS analysis of the branches EE showed the abundant compounds methyl oleate (19.39%), oleic acid (17.09%), 9-octadecenal (15.65%), methyl palmitate (14.08%), and methyl 12,13-tetradecadienoate (8.99%). In the leaves EE, the primary compounds were anabasine (11.44%), palmitic acid (11.29%), oleic acid (10.96%), hydnocarpic acid (8.34%), and hexahydrofarnesyl acetone (6.76%). The EEs at 1000 µg/mL exhibited the best activity against the growth of P. glomerata, P. tardicrescens, and F. circinatum with fungal inhibition percentage (FIP) values of (35.92% and 27.77%), (58.15% and 47.41%), and (55.55 and 55.18%), respectively. The MICs with the branch and leaf extract ranged from 15.6 to 250 µg/mL with all fungal isolates. This study offers significant and important applications of Nicotiana glauca as a source of natural extracts for wood-biofungicides application against some fungi isolated from diseased branches and roots of Pinus halepensis.