Chemical Composition, Antifungal Activity and Molecular Docking Study of Essential oil of Rhabdocaulon lavanduloides Benth

Introduction The Rhabdocaulon lavanduloides species is a native plant found in the Atlantic Forest biome, which produces essential oil and belongs to the Lamiaceae family. It is popularly called Alfazema do campo . Objective Based on this premise the objective of this study was to elucidate the chemical composition of R. lavanduloides essential oil and evaluate its intrinsic and combined antifungal activity against Candida spp. strains. Methodology The essential oil components were identified by gas chromatography coupled with mass spectrometry (GC-MS). For antifungal activity, the broth microdilution method was used to obtain the cell viability curve and determine the mean inhibitory concentration (MIC). The minimum fungicidal concentration (MFC) was evaluated by subculturing in Petri dishes. Results and Discussion Aromatic monoterpenes were the main compounds identified as 2-methoxy-carvacrol, being the majority, followed by thymol, methyl ether, p -cymene, 2,3-dimethoxy- p -cymene, and β -caryophyllene. The antifungal results showed that the essential oil had no intrinsic action in inhibiting the strains; however, when combined with the antifungal agent, it reduced the effective concentration of fluconazole at concentrations of 8 to 32 µg/mL for the standard strain of C. albicans . A minimum fungicidal concentration of 2048 µg/mL was observed in the combination for the isolated strain of C. tropicalis . In addition, molecular docking simulations indicate that 3-isopropyl-2-methoxy-6-methylphenol exhibits a similar affinity profile to Fluconazole across all tested biological receptors, likely through competitive interaction. These findings suggest that 3-isopropyl-2-methoxy-6-methylphenol has potential therapeutic applications against these receptors. Conclusion The essential oil of R. lavanduloides has potential for future antimicrobial research evaluating the antifungal effect of its isolated phytoconstituents.