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.