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The invasion of Candida albicans is one of the most common fungal infections seen in clinical practice, and serious drug resistance has been reported in recent years. Therefore, new anti-C. albicans drugs must be introduced. In this research, it was demonstrated that cinnamaldehyde (CA) shows strong antimicrobial activity, with 0.26 mg/mL CA being the minimum inhibitory concentration to manage C. albicans. Extraordinarily, we detected that CA accumulated the intracellular reactive oxygen species (ROS) and enhanced the calcium concentration in the cytoplasm and mitochondria through flow cytometry. In addition, we observed that C. albicans cells released Cytochrome c from the mitochondria to the cytoplasm, depolarized the mitochondrial membrane potential, and activated the metacaspase when exposed to 0.065, 0.13, 0.26, and 0.52 mg/mL CA. Furthermore, to confirm that CA introduces the C. albicans apoptosis, we discovered that when the phosphatidylserine was exposed, DNA damage and chromatin condensation occurred, which were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and 4',6-diamidino-2-phenylindole (DAPI) staining. Finally, demonstrations of phenotype investigation, colony-forming unit (CFU) counts, and periodic acid-Schiff (PAS) staining were conducted to prove that CA possessed the ability to treat oropharyngeal candidiasis (OPC) and vulvovaginal candidiasis (VVC). From the above, our research indicates that CA is a promising antifungal candidate when applied to C. albicans infections.

New anti-Candida albicans drugs are needed due to the emergence of resistant cases in recent years. Perillaldehyde (PAE) is a natural monoterpenoid compound derived from Perilla frutescens. The minimum inhibitory concentration of PAE against C. albicans was 0.4 μL/mL. We aimed to elucidate the antifungal mode of action of PAE against C. albicans. The antifungal activity of PAE against C. albicans was found to correlate with an elevation in intracellular Ca 2+ and accumulation of ROS. Several downstream apoptosis events such as the disruption of mitochondrial membrane potential, phosphatidylserine externalization, cytochrome c release, and metacaspase activation were observed in PAE-treated cells. DNA damage and nuclear fragmentation assays also revealed apoptosis of C. albicans cells. In summary, by means of fluorescent microscopy, flow cytometer analysis, and Western blot, our data uncovered that PAE exerts its antifungal activity through Ca 2+ and oxidative stress-mediated apoptosis mechanisms. This study deciphered the mode of action of PAE, which will be useful in the design of improved antifungal therapies.

Vulvovaginal candidiasis (VVC) is one of the most frequent diseases induced by Candida albicans (C. albicans) during pregnancy, which results in enormous pain to women and their partners in daily life. Perillaldehyde (PAE), a natural monoterpenoid, has significant anti-microbial, anti-inflammatory and anti-oxidation effects. Reactive oxygen species (ROS) are key factors for the host to resist the invasion of fungi. However, excess ROS can cause additional damage independent of the pathogen itself, and the mechanism of ROS in VVC has not been investigated. In this murine study, we revealed that C. albicans infection increased the expression of NADPH oxidase 2 (NOX2) and the content of malonaldehyde (MDA). C. albicans inhibited the activity of antioxidant enzymes in the vagina, including superoxide dismutase (SOD), Catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase (HO-1), which were returned to normal levels after treatment with PAE. Furthermore, PAE inhibited the activities of Keap1 and promoted Nrf2 transfer from cytoplasm to nucleus, which were mediated by excessive accumulation of ROS in the VVC mice. In this study, we also indicated that PAE inhibited the apoptosis of vagina cells via Caspase 9- Caspase 7-PARP pathway and prevented the release of IL-1ꞵ in VVC mice. In summary, this study revealed that the treatment of VVC in mice with PAE might be mediated by inhibition of ROS, and established the therapeutic potential of PAE as an antifungal agent for the treatment of VVC. [ABSTRACT FROM AUTHOR]