Essential Oils of Melaleuca leucadendra and Melaleuca quinquenervia: Chemical Composition and Efficacy Level in Controlling in Vitro Isolates of Potentially Aflatoxin-Producing Aspergillus flavus

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Among the mycotoxins of health and economic importance, aflatoxins hold a prominent place. This study aims to determine the chemical composition of the essential oils of Melaleuca leucadendra and Melaleuca quinquenervia, and to evaluate their effectiveness in the in vitro control of an Aspergillus flavus strain isolated from peanut seeds in Senegal. Essential oils were extracted from air-dried leaves collected in Fatick and the Mbao Classified Forest using hydrodistillation with a Clevenger-type apparatus. Chemical characterisation was performed using gas chromatography (GC-FID) and gas chromatography–mass spectrometry (GC-MS). Data were statistically analyzed using ANOVA and Student–Newman–Keuls tests at a 5% significance level. The chemical composition analysis of the essential oils revealed high identification rates of 96.8% for Melaleuca quinquenervia and 99.9% for Melaleuca leucadendra. The antifungal assays demonstrated a strong dose-dependent inhibitory effect of both essential oils against Aspergillus flavus ThC2. M. quinquenervia exhibited the highest activity, with inhibition rates ranging from 71.8% at 100 ppm to 92.3% at 1000 ppm. M. leucadendra showed moderate activity, with inhibition ranging from 44.2% to 63.0% across the same concentrations. Overall, the results indicate that both essential oils, particularly that of M. quinquenervia, exhibit strong antifungal potential against A. flavus. Essential oils derived from Melaleuca quinquenervia and Melaleuca leucadendra exhibit distinct chemical compositions that contribute to notable biological activities. These oils demonstrate strong inhibitory effects on mycelial growth and sporulation of Aspergillus flavus, along with a moderate capacity to reduce aflatoxin biosynthesis. Owing to their diverse bioactive compounds and multi-target mechanisms of action, certain essential oils display antimicrobial properties that can surpass those of conventional synthetic agents while reducing the likelihood of resistance development in microorganisms. Consequently, these natural products show significant potential as effective alternatives in integrated biological control strategies aimed at managing crop and stored-product pathogens, particularly aflatoxin-producing fungi.

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