Quinalizarin as a potential antifungal drug for the treatment of Candida albicans fungal infection in cancer patients

Abstract

This study aims to analyze the antifungal properties of quinalizarin, a plant-derived compound with proven anticancer effects. Quinalizarin exhibited antifungal activity against opportunistic pathogenic Candida species and Geotrichum capitatum. The treatment with this anthraquinone reduced hyphal growth, inhibited biofilm formation, and damaged mature Candida albicans biofilms. Real-time RT-PCR revealed that quinalizarin downregulated the expression of hyphae-related and biofilm-specific genes. The flow cytometry method used in the study showed that both apoptosis and necrosis were the physiological mechanisms of quinalizarin-induced C. albicans cell death, depending on the dose of the antifungal agent. A further study revealed an increase in the levels of intracellular reactive oxygen species and alterations in mitochondrial membrane potential after treatment with quinalizarin. Finally, quinalizarin was found to have low toxicity in a hemolytic test using human erythrocytes. In conclusion, we have identified quinalizarin as a potential antifungal compound.IMPORTANCEThis article is a study to determine the antifungal activity of quinalizarin (1,2,5,8-tetrahydroxyanthraquinone). Quinalizarin has potential antitumor properties and is effective in different types of tumor cells. The aim of the present study was to prove that quinalizarin can be used simultaneously in the treatment of cancer and in the treatment of intercurrent fungal infections. Quinalizarin was identified as a novel antifungal compound with low toxicity. These results may contribute to the development of a new drug with dual activity in the treatment of cancer-associated candidiasis.

Keywords: Candida albicans; Candida auris; ROS; SEM; anthraquinones; antifungal activity; biofilm; cancer; fungal infection; hyphae; quinalizarin.

Fig 1

Microscopic images of whole C. albicans ATCC 10231 colonies in solid RPMI 1640 medium supplemented with 10% FBS and quinalizarin at 2 and 4 µg/mL (A1–A3, magnification 40×; B1–B3, magnification 200×); microscopic images of C. albicans cells in liquid RPMI 1640 medium supplemented with 10% FBS and quinalizarin at 2 and 4 µg/mL (C1–C3, magnification 1,000×); reduction of the number of hyphae-forming colonies (D) and hyphae-forming cells (E) induced by quinalizarin at 2 and 4 µg/mL. Data are expressed as mean ± standard error of three independent experiments. *P < 0.05; **P < 0.01; and ***P < 0.001 [significance compared to the control (untreated cells) set at 100%].

Fig 2

Effect of quinalizarin on biofilm formation by C. albicans and reduction of mature biofilm metabolic activity (A) and biomass (B). Representative scanning microscopy images of C. albicans biofilm, control (untreated) cells (C1); treatment with quinalizarin at 8 µg/mL (C2), 16 µg/mL (C3), and 80 µg/mL (C4). Data are expressed as mean ± standard error of three independent experiments. *P < 0.05; **P < 0.01; and ***P < 0.001 [significance compared to the control (untreated cells) set at 100%].

Fig 3

Relative expression of hyphae-related and biofilm-related genes detected by qreal-time PCR. Quinalizarin was used at 4 and 8 µg/mL. The level of gene expression was displayed after normalization with the internal control housekeeping gene ACT1. Data are expressed as mean ± standard error of three independent experiments. **P < 0.01 and ***P < 0.001 [significance compared to the control (untreated cells) set at 1.0].

Fig 4

Effect of quinalizarin on early apoptosis, late apoptosis, and necrosis determined by Annexin V and propidium iodide staining. Control (untreated) cells (A); treatment with quinalizarin at 4 µg/mL (B), 8 µg/mL (C), and 16 µg/mL (D). Values are expressed as mean ± S.E. (Standard Error), %. #Untreated cells were used as a control. *Significant difference with the untreated group (P < 0.05).

Fig 5

Effect of quinalizarin on various markers of apoptosis. ROS production determined by CM-H2DCFDA staining (A). 100 mM H₂O₂ was used as a positive control; mitochondrial membrane potential determined by JC-10 staining (B), 50 µM FCCP was used as a positive control; level of DNA loss demonstrated by DAPI staining (C); genomic DNA samples after electrophoresis on 1% agarose gel (D). Data are expressed as mean ± standard error of three independent experiments. *P < 0.05; *P < 0.01; and ***P < 0.001 [significance compared to the control (untreated cells) set at 1.0].

Fig 6

Effect of quinalizarin on human erythrocytes. Triton X-100 and PBS were used as positive and negative controls, respectively. Data are expressed as mean ± standard error of three independent experiments. ***P < 0.001 (significance compared to the positive control set at 100%).