Antioxidative mechanism of Quercus infectoria gall aqueous extract against Candida albicans

Abstract

Aims:The effect of Quercus infectoria (QI) gall extract on the fungal expression of antioxidant defense enzymes of Candida albicans was studied in an effort to unravel its anti-fungal mechanism. Methodology and results: Minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and time kill assays were conducted to analyse the antifungal activity of the extract against C. albicans. Total protein profiles of C. albicans were determined by SDS-PAGE and real-time PCR was used to quantify the genes expression level of superoxide dismutase (SOD1), catalase (CAT1) and glutathione peroxidase (GPX3) following treatment with aqueous QI gall extract. The MIC and MFC values of the extract against C. albicans were 8 mg/mL and 16 mg/mL respectively. Fungistatic and fungicidal activities of the extract were observed after 24 h at 1× MIC and 2× MIC from the time-kill assay. A lower total protein bands density of extract-treated C. albicans was visualized when compared to the untreated cells at concentrations of 1× MIC and 2× MIC. A significant reduction in the expression of GPX3 (p <0.05) was observed following 2 h treatment of extract at 1× MIC and 2× MIC though it did not significantly affect those of SOD1 and CAT1 (p >0.05). Conclusion, significance and impact of study:In conclusion, QI gall extract exerted an anti-Candida activity and it is apparently effective in downregulating the gene expression of GPX3 in C. albicans. Of note, the present findings elucidated a preliminary mechanism associated with the organism's survival resilience which represents a key target for the development of anti-Candida agents in future.