Piperazine Derivatives Suppress Candida Albicans Infection By Interfering Hyphal Morphogenesis

Candida albicans(C.albicans),an important opportunistic pathogenic yeast,remains the main etiological agent of candidiasis,which causes active infection not only in normal commensal of humans but also in immune-and medically-compromised patients as resulting more severe systemic Candida infection and even death.Nowadays,bloodborne infections and mucosal infection arising from C.albicans are an increasingly recognized complication of modern medicine and an especially serious concern in the nosocomial setting.As the limited development of antifungal drugs and the frequent occurrence of drug resistance,the research has been forced to shift to novel drug targets exploitation like targeting toxicity mechanism,which is a favorable choice for antifungal agents and is different from traditionally drugs killing or inhibit fungal cell growth directly.As a typical dimorphic pathogen,C.albicans initiate adhesion and implantation to human host cells by converting the sterile yeast to the pathogenic mycelium,forms the colonization biofilm in the end.More and more studies have provided important insights in the pathogenic factors and pathogenesis of C.albicans,among which hyphae formation is the most high-profiled one,and it is expected to be a target of strategies to treat C.albicans.Piperazine derivatives are a class of small molecular compounds with piperazine groups.As one of the main objects of new drug research,their effects are mainly concentrated on anti-inflammation,anti-tumor and anti-anxiety,but on anti-fungal relatively few.In this study,novel piperazine derivatives LF series and J series were synthesized using the aryl benzene ring as the main framework and were tested the efficacy against C.albicans SC5314 pathogenicity by the inhibition of yeast-to-hypha transition,at the same time,the possible mechanism of their action was preliminarily studied.The main study results are as follows:1?The screening of targeted toxic factors includes the yeast-to-hyphae transformation,biofilm and adhesion formation,cytotoxicity and the mice infection model,also focuses on the effect of molecular compounds on the growth of C.albicans and the inhibitory capability on the other fungal species.The result of small molecule screening reveals that the compound 1c and 28 e in LF series ? No.27 in J series are in line with experimental expectations.2?Piperazine derivatives LF series contains 25 new structure.Several compounds had no effect on the normal growth of C.albicans,but strongly inhibited the morphological transition and adhesion.The leading compound,1c(1-(4-methoxyphenyl)-4-(3-phenoxy-2-hydroxypropyl)-piperazine)and 28e(1-(4-ethoxyphenyl)-4-(1-biphenylol-2-hydroxypropyl)-piperazine),can significantly reduce the cytotoxicity by attenuating the hyphal formation yet showed no toxicity to human A549 cells at the screening concentration of 100?M,and proving its broad spectrum by showing inhibition effect on the other trains.Therefore,compound 1c and 28 e may be developed into clinical therapeutic agents on inhibition of fungal cell morphological transformation and toxicity.3? 20 compounds are belonging to new structure among the J series piperazine derivatives.Structure-activity relationship analysis showed that xx modification could interfere and weaken the mycelial transformation of C.albicans obviously,otherwise,compound modified by indole ring could impair the cytotoxicity and the occurrence of biofilm.The compound No.25-No.28 improved the survival rate and decreased the staining ability of C.albicans in mouse stomatological infection model(OPC model).No.27(1-(2-bromophenyl)-4-(3-(5-carbazooxy)-2-hydroxypropyl)piperazine)also showed strong inhibition to other fungal pathogenic bacteria and drug-resistant strains,which providing a certain broad-spectrum and the possibility of No.27 as a potential therapeutic drug.4?RT-PCR results display that,filamentous morphogenesis,adhesion,biofilm formation and the expression of related gene reducing significantly after No.27 treatment which were evenly distributed in MAPK and c AMP-PKA,two classic hyphal regulatory pathways.Inaddition,the analysis of RNA-Seq results showed that No.27 had a concentrated effect on peroxygenase-related genes,reflecting the oxidative stress response of C.albicans under environmental stress.These results indicated that compound No.27 had a multidirectional and complex inhibitory effect on the pathogenicity of Candida albicans.Moreover,No.27 also exhibited a certain inhibitory effect on the activity of drug-resistant strains.According to the analysis of the whole genome sequencing results of fluconazole resistant strain,No.27 may act a different way of action comparing with the clinical drug fluconazole in the treatment of Candidiasis.This project is based on high-throughput careening of small molecule compounds,and the candidate compounds will provide new ideas and theoretical basis for the development of clinical therapeutic drugs for the treatment of Candidiasis in the future.