Essential oil from Artemisia gmelinii extenuates cellular integrity of Sporothrix globosa and its biofilms by steering intracellular ROS and basal ergosterol levels.

AIM: Sporotrichosis is a fungal zoonotic infection caused by the pathogenic clade of the Sporothrix species complex. Considered a neglected tropical disease, sporotrichosis now has a cosmopolitan distribution through species like Sporothrix globosa. Moreover, multi-drug-resistant S. globosa strains are refractory to conventional antifungal therapy. The present study explores the anti-sporotrichotic effects of the essential oil of Artemisia gmelinii leaves (AgLEO) against a multi-drug-resistant strain of S. globosa.

METHODS: Gas chromatography-tandem mass spectrometry (GC-MS/MS) was performed for chemical profiling of AgLEO. Broth microdilution assay determined the inhibitory concentration of AgLEO against S. globosa. Oxidative stress in yeast was evaluated using the H2-DCFDA assay. Calcofluor white staining highlighted morphological changes in S. globosa under a fluorescent microscope. Ultra-high-performance liquid chromatography (UHPLC) determined total ergosterol levels in S. globosa. Biofilm formation was assessed by lactophenol cotton blue staining followed by brightfield microscopy.

RESULTS: GC-MS/MS analysis revealed that AgLEO is rich in oxygenated monoterpenes, sesquiterpene hydrocarbons, monoterpene hydrocarbons, and oxygenated sesquiterpenes. S. globosa yeast cells exhibited a dose-dependent susceptibility to AgLEO, with minimum inhibitory concentrations (MIC50 and MIC90) of 0.3% (v/v) and 0.4% (v/v), respectively. Mechanistic investigations demonstrated that AgLEO induces intracellular accumulation of reactive oxygen species (ROS) within 4 h of treatment, indicating oxidative stress-mediated cellular damages in S. globosa. Calcofluor white staining highlighted distorted and attenuated hyphal structures in S. globosa with AgLEO. Subsequently, UHPLC analysis also revealed a significant reduction of total ergosterol content in S. globosa with AgLEO. Together, these findings suggest that AgLEO-induced loss of structural integrity in S. globosa impaired the biofilm formation in S. globosa yeast cells.

CONCLUSIONS: This study provides the first mechanistic evidence of AgLEO as an effective herbal agent against drug-resistant S. globosa. AgLEO exhibit multi-faceted anti-sporotrichotic effects by ROS induction, structural destabilization, ergosterol depletion, and biofilm inhibition. The outcome of the current study provides a promising botanical approach for sporotrichosis management and paves the way for developing plant-driven anti-sporotrichotic therapy.