Lavandula angustifolia Mill. essential oil impairs chitin synthesis and morphogenesis in Aspergillus fumigatus Fresenius.

Aspergillus fumigatus Fresenius is significant pathogen in immunocompromised individuals. This study evaluated the antifungal activity of Lavandula angustifolia Mill., (Lamiaceae) essential oil (LAEO) against A. fumigatus strain from a cystic fibrosis patient, focusing on chitin synthesis and hyphal morphology. LAEO showed MIC of 4425 μg/mL, compared to 0.25 µg/mL for voriconazole, 1 µg/mL for amphotericin B, and 2 µg/mL for caspofungin. A synergistic effect was observed only between LAEO and caspofungin. Chitin content quantified by calcofluor white fluorescence and expressed as mean gray value (MGV), was markedly reduced in LAEO-treated hyphae (33.8 MGV) compared to the untreated control (80.4 MGV), amphotericin B (74.7 MGV), voriconazole (84.1 MGV), and caspofungin (106.3 MGV). LAEO reduced hyphal thickness (1.9 µm) compared to untreated control (3.6 µm), amphotericin B (3.9 µm), voriconazole (4.1 µm), and caspofungin (4.4 µm). These findings indicate that LAEO interferes with chitin synthesis and compromises hyphal integrity in A. fumigatus.