Investigating the potential antibacterial, anti-biofilm, wound healing and anti-inflammatory activity of the extract of Aspergillus niger endophyte isolated from cucumber leaves: in vitro and in vivo study

BACKGROUND: Endophytic fungi are a vast inventory of bioactive compounds, offering potent, cost-effective, renewable, and low-toxicity alternatives for therapeutic applications. The current investigation focused on the endophytic fungus Aspergillus niger, which was isolated for the first time from Cucumis sativus (cucumber) leaves and subjected to comprehensive evaluation, including anti-inflammatory, antibacterial, anti-biofilm, and in vitro wound healing potential. 18 S rRNA gene sequencing was utilized to identify A. niger after isolation, and the fungus was cultivated on Asian rice to produce fungal metabolites. The high-resolution liquid chromatography-mass spectrometry (LC-HRESI-MS/MS) was then used to elucidate its phytochemical profile. RESULTS: Fingerprint compounds detected in the ethyl acetate of the endophyte A. niger (ANM) revealed 15 compounds that are mainly pyrones and quinones in nature, including citric acid, nigerasperone A, aspernigrin A, aspinonene, campyrone B, aurasperone F, and plastoquinone-3. The ANM showed a strong antibacterial activity against S. aureus clinical isolates (MIC values ranging from 32 to 512 µg/mL) and a significant reduction in biofilm formation, where the total number of biofilm producers, S. aureus isolates, decreased from 19 to 6 after treatment with ½ MIC of ANM. Furthermore, ANM-treated WI38 human fibroblast cells displayed a wound closure percentage of 99.68% ± 0.02 compared to 83.37% ± 0.05 for the control cells. Additionally, the ANM demonstrated potential in promoting wound healing, particularly in infected wounds, through its antimicrobial, anti-inflammatory, and tissue-regenerating properties. CONCLUSIONS: These findings highlight A. niger as a valuable source of natural therapeutics. Additional research is needed to explore its key active components and potential side effects.