Novel Nystatin A1 derivatives exhibiting low host cell toxicity and antifungal activity in an in vitro model of oral candidosis

Abstract

Opportunistic oral infections caused by Candida albicans are frequent problems in immunocompromised patients. Management of such infections is limited due to the low number of antifungal drugs available, their relatively high toxicity and the emergence of antifungal resistance. Given these issues, our investigations have focused on novel derivatives of the antifungal antibiotic Nystatin A1, generated by modifications at the amino group of this molecule. The aims of this study were to evaluate the antifungal effectiveness and host cell toxicity of these new compounds using an in vitro model of oral candidosis based on a reconstituted human oral epithelium (RHOE). Initial studies employing broth microdilution, revealed that against planktonic C. albicans, Nystatin A1 had lower minimal inhibitory concentration than novel derivatives. However, Nystatin A1 was also markedly more toxic against human keratinocyte cells. Interestingly, using live/dead staining to assess C. albicans and tissue cell viability after RHOE infection, Nystatin A1 derivatives were more active against Candida with lower toxicity to epithelial cells than the parent drug. Lactate dehydrogenase activity released by the RHOE indicated a fourfold reduction in tissue damage when certain Nystatin derivatives were used compared with Nystatin A1. Furthermore, compared with Nystatin A1, colonisation of the oral epithelium by C. albicans was notably reduced by the new polyenes. In the absence of antifungal agents, confocal laser scanning microscopy showed that C. albicans extensively invaded the RHOE. However, the presence of the novel derivatives greatly reduced or totally prevented this fungal invasion.

Alginate oligosaccharides modify hyphal infiltration ofCandida albicansin anin vitromodel of invasive human candidosis

“…; Boros‐Majewska et al . ), which revealed that as OligoG was not fungicidal (as ascertained by the absence of red‐stained, non‐vital cells), differential quantification of samples, as previously described by Boros‐Majewska et al . (), could not be employed.…”

“…), which revealed that as OligoG was not fungicidal (as ascertained by the absence of red‐stained, non‐vital cells), differential quantification of samples, as previously described by Boros‐Majewska et al . (), could not be employed. Analysis of invasion in the RHE and agar models revealed that while no differences in fungal viability were evident, OligoG treatment induced markedly reduced invasion in both model systems, with a dose‐dependent decrease in hyphal formation being evident in the agar model.…”

“…While attachment, proliferation and biofilm assembly are important in the colonization of the epithelial surface, invasion is a key pathogenic phenotype in candidal pathogenesis (Bartie et al 2004;Mayer et al 2013). Invasion studies here employed cross-sectional imaging of RHE as previously utilized in virulence studies of clinical Candida isolates (Malic et al 2007;Boros-Majewska et al 2014), which revealed that as OligoG was not fungicidal (as ascertained by the absence of red-stained, non-vital cells), differential quantification of samples, as previously described by Boros-Majewska et al (2014), could not be employed. Analysis of invasion in the RHE and agar models revealed that while no differences in fungal viability were evident, OligoG treatment induced markedly reduced invasion in both model systems, with a dosedependent decrease in hyphal formation being evident in the agar model.…”

Antifungal potential ofSideroxylon obtusifoliumandSyzygium cuminiand their mode of action againstCandida albicans

“…In addition, some of synthetic antifungals are potentially toxic for the host cells due to the similarity in both eukaryotic fungal and human cell components, such as sterols (Berman & Sudbery 2002). Biochemical engineering has been used to modify standard antifungals or even develop novel lowtoxicity drugs (Boros-Majewska et al 2014;Peng et al 2015), but most drugs have not been tested in humans. Taken together, all these aspects have encouraged an active search for novel candidates to manage oral candidiasis in susceptible patients.…”

Structural modifications and yield improvements of polyene macrolide antibiotics

“…多烯大环内酯抗生素的溶血毒性 [56] , 尤其是C3′位氨 基的二(氨基丙烷基)衍生(如两性霉素B衍生物28, 图 4)可以使衍生物的抗真菌活性提高10倍以上, 而溶 血毒性下降2.5倍左右(表1) [32] . 环外羧基衍生与C3′ 位氨基衍生相结合, 能够进一步提高多烯大环内酯 衍生物的抗真菌活性, 并降低其溶血毒性 [57] .…”