Chemical composition of Artemisia argyi essential oil and its antifungal activity against dermatophytes by inhibiting oxidative phosphorylation and causing oxidative damage

Abstract

Ethnopharmacological relevance: Dermatophytes are notorious pathogens capable of infecting various mammals skin, posing serious threats to human health and overall life quality worldwide. Artemisia argyi has been recorded and applied for over a thousand years to treat skin itching. Although it has the potential to be developed as a plant-based antifungal agent, it's antifungal activity and action mechanism of active ingredients are still unclear.

Aim of the study: The aim of this study was to investigate the chemical composition, antifungal activity against skin fungi, and potential mechanisms of Artemisia argyi essential oil (AEO).

Materials and methods: The chemical composition of AEO was analyzed by gas chromatography-mass spectrometry (GC-MS) firstly. Flat growth restraint and double half dilution tests was performed to evaluate AEO antifungal activity against Microsporum gypseum, Trichophyton mentagrophytes, and Trichophyton rubrum. And then, the physiological mechanism of AEO inhibiting dermatophytes was systematically explored through scanning electron microscopy, relative conductivity, membrane leakage, ROS content, and antioxidant enzyme activity. Finally, the main pathways were screened through transcriptome sequencing, while the related genes expression levels and enzyme activity were validated.

Results: Monoterpenes and sesquiterpenoids were the most highly representative class of AEO. AEO had powerful antifungal activity against M. gypseum, T. mentagrophytes, and T. rubrum, with minimum inhibitory concentration (MIC) values of 0.6, 1.2, and 1.2 μL/mL, respectively. Moreover, AEO can also damage the cell membrane integrity of T. mentagrophytes, resulting in cellular extravasation of intracellular substances. Transcriptome analysis revealed that the main target of AEO is to inhibit electron transfer and oxidative phosphorylation during respiration, ultimately leading to obstruction of normal ATP synthesis and energy metabolism in mitochondria. And a large amount of ROS will generate due to the incompletely catalysis of oxygen under mitochondrial complexes. Coupled with the decrease of antioxidant enzyme (SOD, POD) activity, excessive accumulation of ROS will cause serious oxidative damage to cells and eventually exhibiting antifungal activity against dermatophytes.

Conclusions: The present study demonstrated that Artemisia argyi was a valuable source of active compounds with antifungal activity. These findings support AEO as a potential agent to inhibit dermatophytes and prevent related dermatophytoses.

Keywords: Antifungal; Artemisia argyi essential oil; Dermatophytes; Oxidative phosphorylation.