Candida albicans growth and germ tube formation can be inhibited by simple diphenyl diselenides [(PhSe)2, (MeOPhSe)2, (p-Cl-PhSe)2, (F3CPhSe)2] and diphenyl ditelluride

(MeOPhSe)2, a synthetic organic selenium compound, inhibits virulence factors of Candida krusei: Adherence to cervical epithelial cells and biofilm formation

BACKGROUND

Systemic candidiasis is produced by Candida albicans or non-albicans Candida species, opportunistic fungi that produce both superficial and invasive infections. Despite the availability of a wide range of antifungal agents for the treatment of candidiasis, failure of therapy is observed frequently, which opens new avenues in the field of alternative therapeutic strategies.

METHODS

The effects of p,p'-methoxyl-diphenyl diselenide [(MeOPhSe)₂], a synthetic organic selenium (organochalcogen) compound, were investigated on virulence factors of C. krusei and compared with its antifungal effects on the virulence factors related to adhesion to cervical epithelial cell surfaces with C. albicans.

RESULTS

(MeOPhSe)₂, a compound non-toxic in epithelial (HeLa) and fibroblastic (Vero) cells, inhibited the growth in a dose-dependent manner and changed the kinetics parameters of C. krusei and, most importantly, extending the duration of lag phase of growth, inhibiting biofilm formation, and changing the structure of biofilm. Also, (MeOPhSe)₂ reduced C. albicans and C. krusei adherence to cervical epithelial cells, an important factor for the early stage of the Candida-host interaction. The reduction was 37.24 ± 2.7 % in C. krusei (p = 0.00153) and 32.84 ± 3.2 % in C. albicans (p = 0.0072) at 20 µM (MeOPhSe)₂, and the effect is in a concentration-dependent manner. Surprisingly, the antifungal potential on adhesion was similar between both species, indicating the potential of (MeOPhSe)₂ as a promising antifungal drug against different Candida infections.

CONCLUSION

Overall, we demonstrated the potential of (MeOPhSe)₂ as an effective antifungal drug against the virulence factors of Candida species.

Diphenyl diselenide suppresses key virulence factors of Candida krusei, a neglected fungal pathogen

Candida krusei is a candidiasis etiological agent of relevance in the clinical setting because of its intrinsic resistance to fluconazole. Also, it has opened up new paths in the area of alternative therapeutic techniques. This project demonstrated the effects of diphenyl diselenide (PhSe)₂ and p-cloro diphenyl diselenide (pCl-PhSe)₂, two organochalcogen compounds, on relevant virulence factors for the early stage of the C. krusei host interaction and infection process. Both compounds inhibited adherence of C. krusei to both polystyrene surfaces and cervical epithelial cells and biofilm formation; the structure of the biofilm was also changed in a dose-dependent manner. In addition, both compounds inhibited C. krusei growth, but (PhSe)₂ significantly increased the time duration of the lag phase and delayed the start of the exponential phase in growth kinetics. (PhSe)₂ has more potential antifungal activity than (pCl-PhSe)₂ in inhibiting the adherence to epithelial cells, biofilm formation, and growth of C. krusei.

Mucoadhesive gellan gum hydrogel containing diphenyl diselenide-loaded nanocapsules presents improved anti-candida action in a mouse model of vulvovaginal candidiasis

The aim of this study was to evaluate the in vitro antifungal action of a diphenyl diselenide-loaded poly(ε-caprolactone) nanocapsules suspension (NC-1) and incorporate it into a gellan gum hydrogel formulation in order to assess its in vivo efficacy in an animal model of vulvovaginal candidiasis. Nanocapsules suspensions containing the compound (NC-1 ∼ 5 mg/mL) or not (NC-B) were prepared by the interfacial deposition of preformed polymer method. To estimate in vitro antifungal effect, the broth microdilution test was applied. The results showed that NC-1 had equal or lower MIC values when compared to free compound against fifteen Candida strains. Following, the hydrogel was prepared by direct thickening of the nanocapsules suspension by gellan gum addition. The animal model of vulvovaginal candidiasis was induced by infecting female Swiss mice with Candida albicans strains. The animals were topically treated with 20 µL of hydrogels (NC-1 and free compound - 0.1 mg of diphenyl diselenide/once a day for seven days) and then the total fungal burden was assessed after the euthanasia. The results showed that the hydrogels presented pH in the acidic range, compound content close to theoretical value, homogeneous particle distribution with nanometric size, high physicochemical and microbiological stability as well as great bioadhesive property. The nano-based presented superior pharmacological action in comparison to the hydrogel containing non-encapsulated diphenyl diselenide. The results demonstrated that the nanoencapsulation maintained the effective antifungal action of diphenyl diselenide. The nano-based hydrogel formulation may be considered a promising approach against vulvovaginal candidiasis.

(PhSe)2 and (pCl-PhSe)2 organochalcogen compounds inhibit Candida albicans adhesion to human endocervical (HeLa) cells and show anti-biofilm activities

Adhesion capacity on biological surfaces and biofilm formation is considered an important step in the infection process by Candida albicans. The ability of (PhSe)₂ and (pCl-PhSe)₂, two synthetic organic selenium (organochalcogen) compounds, to act on C. albicans virulence factors related to adhesion to human endocervical (HeLa) cell surfaces and their anti-biofilm activities was analyzed. Both organochalcogen compounds inhibited C. albicans adhesion to HeLa cells, dependent on compound concentrations. (PhSe)₂ (at 20 µM; p = 0.0012) was significantly more effective than (pCl-PhSe)₂ (at 20 µM; p = 0.0183) compared with the control. (PhSe)₂ inhibited biofilm formation and decreased biofilm viability in both early and mature biofilms more efficiently than (pCl-PhSe)₂. Overall, the organochalcogen compounds, especially (PhSe)₂, were demonstrated to be effective antifungal drugs against C. albicans virulence factors related to epithelial cell surface adhesion and the formation and viability of biofilms.

Ebselen and diphenyl diselenide against fungal pathogens: A systematic review

Fungal infections are one of the most prevalent diseases in the world and there is a lack of new antifungal drug development for these diseases. We conducted a systematic review of the literature regarding the in vitro antifungal activity of the organoselenium compounds ebselen (Eb) and diphenyl diselenide [(PhSe)2]. A systematic review was carried out based on the search for articles with data concerning Minimal Inhibitory Concentration (MIC) values, indexed in international databases and published until August 2020. A total of 2337 articles were found, and, according to the inclusion and exclusion criteria used, 22 articles were included in the study. Inhibitory activity against 96% (200/208) and 95% (312/328) of the pathogenic fungi tested was described for Eb and [(PhSe)2], respectively. Including in these 536 fungal isolates tested, organoselenium activity was highlighted against Candida spp., Cryptococcus ssp., Trichosporon spp., Aspergillus spp., Fusarium spp., Pythium spp., and Sporothrix spp., with MIC values lower than 64 μg/mL. In conclusion, Eb and [(PhSe)2] have a broad spectrum of in vitro inhibitory antifungal activity. These data added with other pharmacological properties of these organoselenium compounds suggest that both compounds are potential future antifungal drugs. Whether MICs toward the upper end of the ranges described here are compatible with efficacious therapy, and whether they may achieve such end as a result of the favorable non-antimicrobial effects of selenium on the host, requires more in vivo testing.

Reaction of bis[(2-chlorocarbonyl)phenyl] Diselenide with Phenols, Aminophenols, and Other Amines towards Diphenyl Diselenides with Antimicrobial and Antiviral Properties

A reaction of bis[(2-chlorocarbonyl)phenyl] diselenide with various mono and bisnucleophiles such as aminophenols, phenols, and amines have been studied as a convenient general route to a series of new antimicrobial and antiviral diphenyl diselenides. The compounds, particularly bis[2-(hydroxyphenylcarbamoyl)]phenyl diselenides and reference benzisoselenazol-3(2H)-ones, exhibited high antimicrobial activity against Gram-positive bacterial species (Enterococcus spp., Staphylococcus spp.), and some compounds were also active against Gram-negative E. coli and fungi (Candida spp., A. niger). The majority of compounds demonstrated high activity against human herpes virus type 1 (HHV-1) and moderate activity against encephalomyocarditis virus (EMCV), while they were generally inactive against vesicular stomatitis virus (VSV).

‘One-pot’ synthesis and redox evaluations of chiral chalcogenocysteinol and β-bis-chalcogenoamine derivatives from l-serine methyl ester

The synthesis of a new class of potential antioxidant chiral chalcogenocysteinols and bis-chalcogenoamines is described in this study.

Diphenyl diselenide (PhSe)2 inhibits biofilm formation by Candida albicans, increasing both ROS production and membrane permeability

PROJECT

The opportunistic fungal Candida albicans can produce superficial and systemic infections in immunocompromised patients. An essential stage to both colonization and virulence by C. albicans is the transition from budding yeast form to filamentous form, producing biofilms.

PROCEDURE

In this work, we studied the effect of the organochalcogenide compound (PhSe)2 on both cell growth and biofilm formation by C. albicans.

RESULTS

(PhSe)2 inhibited both growth and biofilm formation by C. albicans. The inhibitory effects of (PhSe)2 depended on the cell density and (PhSe)2 concentration. We have also observed that (PhSe)2 stimulated ROS production (67%) and increased cell membrane permeability (2.94-fold) in C. albicans. In addition, (PhSe)2 caused a marked decrease in proteinase activity (6.8-fold) in relation to non-treated group.

CONCLUSIONS

(PhSe)2 decreased both cell growth and biofilm development, decreasing the release of extracellular proteinases, which is an important facet of C. albicans pathogenicity. The toxicity of (PhSe)2 towards C. albicans can be associated with an increase in ROS production, which can increase cell permeability. The permanent damage to the cell membranes can culminate in cell death.