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

Abstract 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 .