Óleo essencial de Piper aduncum no controle in vitro de fungos fitopatogênicos Fusarium oxysporum e Macrophomina phaseolina

Abstract

The increasing resistance of plants to synthetic fungicides, along with growing concerns about environmental sustainability, has driven research into natural alternatives for the control of plant diseases. The genus Piper, widely distributed in Neotropical flora, is a promising source of secondary metabolites with antifungal properties. This study aimed to evaluate the antifungal activity of Piper aduncum essential oil (PAEO) against the phytopathogens Fusarium oxysporum and Macrophomina phaseolina, with the goal of proposing a sustainable alternative for crop management. Plant material was collected in the municipality of Iporá (Brazil), and essential oil was extracted from inflorescences by hydrodistillation using a Clevenger apparatus. Chemical composition was analyzed by gas chromatography coupled to mass spectrometry (Shimadzu GC QP 5000) equipped with a fused silica capillary column (OPTIMA®-5-0.25 µm, 30 m × 0.25 mm). Compounds were identified by comparing retention indices with n-alkane standards (C7– C40) and literature data. In vitro antifungal activity was tested at concentrations of 1.0, 0.5, and 0.1 g·L⁻¹ using the disk diffusion method on PDA medium, with water as the positive control and the commercial fungicide Standak Top® as the negative control. Samples were incubated in a BOD chamber at 25 ± 2 °C with a 12 h photoperiod, and mycelial growth was measured daily until full growth occurred in the positive controls (4 days for Fusarium and 7 days for Macrophomina). The percentage of mycelial growth inhibition (MGI) was calculated for each treatment. Data were analyzed using ANOVA followed by Tukey’s test at 5% significance in SISVAR software. The oil yield was 0.4% ± 0.02. Nineteen compounds were identified, with the main constituents being caryophyllene (18.79%), copaene (11.52%), 1,4,7-cyclodecatriene-1,5,9,9-tetramethyl, Z,Z,Z (10.95%), β-pinene (8.44%), and methyl 4-(3-hydroxy-3-methylbut-1-en-1-yl)- benzoate (8.33%). PAEO effectively inhibited fungal growth, reaching 95.11% inhibition of F. oxysporum and 34.45% of M. phaseolina at 1.0 g·L⁻¹. Similar results were obtained at 0.5 g·L⁻¹ (93.92% and 32.44%, respectively). Even at the lowest concentration (0.1 g·L⁻¹), F. oxysporum growth was reduced by 75.36%. These findings demonstrate the potential of P. aduncum essential oil as a natural and sustainable alternative for managing phytopathogens in agricultural systems.