Aloe-emodin-mediated antimicrobial photodynamic therapy against dermatophytosis caused by Trichophyton rubrum.

Trichophyton rubrum is responsible for the majority of dermatophytosis. Current systemic and topical antifungals against dermatophytosis are often tedious and sometimes unsatisfactory. Antimicrobial photodynamic therapy (aPDT) is a non-invasive alternative suitable for the treatment of superficial fungal infections. This work investigated the photodynamic inactivation efficacy and effects of aloe-emodin (AE), a natural photosensitizer (PS) against T. rubrum microconidia in vitro, and evaluated the treatment effects of AE-mediated aPDT for T. rubrum-caused tinea corporis in vivo and tinea unguium ex vivo. The photodynamic antimicrobial efficacy of AE on T. rubrum microconidia was evaluated by MTT assay. The inhibition effect of AE-mediated aPDT on growth of T. rubrum was studied. Intracellular location of AE, damage induced by AE-mediated aPDT on cellular structure and surface of microconidia and generation of intracellular ROS were investigated by microscopy and flow cytometry. The therapeutic effects of AE-mediated aPDT against dermatophytosis were assessed in T. rubrum-caused tinea corporis guinea pig model and tinea unguium ex vivo model. AE-mediated aPDT effectively inactivated T. rubrum microconidia in a light energy dose-dependent manner and exhibited strong inhibitory effect on growth of T. rubrum. Microscope images indicated that AE is mainly targeted to the organelles and caused damage to the cytoplasm of microconidia after irradiation through generation of abundant intracellular ROS. AE-mediated aPDT demonstrated effective therapeutic effects for T. rubrum-caused tinea corporis on guinea pig model and tinea unguium in ex vivo model. The results obtained suggest that AE is a potential PS for the photodynamic treatment of dermatophytosis caused by T. rubrum, but its permeability in skin and nails needs to be improved.

Aloe-emodin-mediated antimicrobial photodynamic therapy against multidrug-resistant Acinetobacter baumannii: An in vivo study.

BACKGROUND AND AIM: Antimicrobial photodynamic therapy (aPDT) has shown great potential for treatment of superficial or localized multidrug-resistant (MDR) Acinetobacter baumannii infections. The purpose of this study was to investigate the cytotoxicity and in vivo safety of aloe-emodin (AE), and its photodynamic treatment efficacy against MDR A. baumannii infections. METHODS: The cytotoxicity (dark toxicity) and phototoxicity of AE to human immortalized keratinocytes and mice fibroblasts were detected by CCK-8 kit. Low and high doses of AE were intravenously injected into mice to evaluate the safety of AE in vivo. Bioluminescent MDR A. baumannii strain was employed to establish the infection model on BALB/c mice after skin scald, and infection status and therapeutic effect of AE-mediated aPDT were assessed by animal imaging system. The peripheral blood of mice was analyzed by flow cytometer. RESULTS: AE had low cytotoxicity to human immortalized keratinocytes and mice fibroblasts, and had certain phototoxicity to these cells under light irradiation. The in vivo experiments demonstrated that AE caused no obvious effects on the weight and pathological changes of mice. AE-mediated aPDT was effective in the treatment of MDR A. baumannii caused infections in mice after skin scald. CONCLUSIONS: AE has potential to be used in the photodynamic treatment of MDR A. baumannii caused superficial infections after scald.

The effects of aloe emodin-mediated antimicrobial photodynamic therapy on drug-sensitive and resistant Candida albicans.

The extensive and repetitive use of antifungal drugs has led to the development of drug-resistant Candida albicans. Antimicrobial photodynamic therapy (aPDT) has received considerable attention as an emerging and promising approach to combat drug-resistant microbes. This study evaluated the photodynamic effects mediated by aloe emodin (AE), a natural compound isolated from Aloe vera and Rheum palmatum, on azole-sensitive and azole-resistant C. albicans in vitro. AE exhibited no significant dark toxicity, but in the presence of light, effectively inactivated C. albicans cells in a concentration-dependent manner. The uptake of AE by fungal cells was investigated by confocal laser scanning microscopy (CLSM), and the results showed that AE possessed stronger ability to enter into C. albicans cells following light irradiation. Transmission electron microscopy analysis suggested that AE-mediated aPDT could induce damage to the cell wall, cytoplasm, and nucleus. Damage to the surface of C. albicans was observed by scanning electron microscopy. These results suggest that AE is a potential PS for use in aPDT of drug-resistant C. albicans strains, and AE-mediated aPDT shows promise as an antifungal treatment.

Antimicrobial photodynamic therapy against multidrug-resistant Acinetobacter baumannii clinical isolates mediated by aloe-emodin: An in vitro study.

BACKGROUND AND AIM: Antimicrobial photodynamic therapy (aPDT) has received considerable attention as an emerging and promising approach for treating superficial infections. The aim of this study was to investigate aPDT mediated by aloe emodin (AE), a natural compound isolated from Aloe vera and Rheum palmatum, against multidrug-resistant (MDR) Acinetobacter baumannii clinical isolates in vitro. METHODS: The photodynamic inactivation (PDI) efficacies of AE on three MDR A. baumannii isolates were assessed by colony forming units (CFU) assay. The aPDT effects mediated by AE on the genomic DNA, membrane integrity, and cellular structure of MDR A. baumannii were also investigated. RESULTS: AE showed no obvious dark toxicity, but inactivated the MDR A. baumannii isolates in an AE concentration and light energy dose-dependent manner. Agarose gel electrophoresis and LIVE/DEAD BacLight Bacterial Viability kit assay indicated that the genomic DNA and membrane integrity of MDR A. baumannii were damaged after AE-mediated aPDT treatment. Transmission electron microscopy (TEM) images demonstrated that AE-mediated aPDT could induce rupture of bacterial cell wall and membrane, and condensation of ribosomes in the cytoplasm. CONCLUSIONS: The results obtained in this study suggested that AE could serve as a potential antibacterial photosensitizer in the treatment of superficial infections caused by MDR A. baumannii.