The Novel Antifungal Inhibitors Of SE And CYP51 As Targets:Design,Synthesis And Bioactivity Study

In recent years,with the increasing number of immunodeficient patients and the extensive use of chemotherapy drugs,the fungal infection rate has risen sharply.At present,most antifungal drugs in clinical use generally show some disadvantages,such as narrow antifungal spectrum,side effects and drug resistance.Therefore,it is a very important task for many drug researchers to develop new antifungal drugs with broad spectrum,low toxicity and high efficiency.Squalene epoxidase(SE)and sterol 14α-demethylase(CYP51)are key enzymes in the fungal ergosterol biosynthesis pathway.And they are also important targets for the development of antifungal drugs.This paper mainly focuses on the design,synthesis and bioactivity study of target compounds around SE and CYP51,which can be classified into the following three parts:Part Ⅰ: The pharmacophore models based on SE inhibitor and CYP51 inhibitor were constructed,and the appropriate organic active fragments were selected.Then three target compounds were designed and synthesized by matching and linking organic active fragments.The antifungal activities in vitro showed that all the target compounds showed certain antifungal activity,the perfected target compound 8 showed the high-efficiency and broad-spectrum antifungal activity.Preliminary mechanism studies demonstrated that compound 8 could increase the content of lanosterol(caused by inhibiting CYP51)and squalene(caused by inhibiting SE),and may have dual-target enzyme(SE/CYP51)inhibitory activity.The above results verify the reliability of pharmacophore model and lay a foundation for the design and development of dual-target antifungal inhibitors in the future.Part Ⅱ: We found that there are similarities between the two kinds of inhibitors in the core region through analyzing the structural characteristics of SE inhibitor and CYP51 inhibitor.On this basis,a series of arylamide derivatives(a total of 24 target compounds)were designed and synthesized based on the dual-target characteristics.Then their bioactivities were determined.In vitro antifungal activity studies showed that most of the target compounds showed good antifungal activity,and the preferred target compounds14 b and 13 d showed better antifungal activities against fungi and drug-resistant fungi than the positive control drugs(naftifine and fluconazole).The synergistic inhibitory effect of these compounds was further confirmed by the analysis of the sterols in the fungal cell membrane.In addition,the animal studies of the preferred target compounds 14 b and 13 d showed that they had good antifungal activities,low toxicity in vivo and had the potential for further development.Part Ⅲ: Fistly,the commen antifungal inhibitors were selected.Then antifungal fragment library was constructed by extracting active fragments.Next,the optimal fragment structures in key region of double targets were screened.Then they are combined and connected to design and synthesize arylalkene-amide compounds and their derivatives(a total of 24 target compounds).Subsequently,the antifungal activity of the target compounds was determined.In vitro antifungal results showed that most of the target compounds had antifungal activity.In particular,compounds 32 i and 37 i showed excellent antifungal activity and could enter into cells,causing fungal cell lysis and death.Preliminary mechanism studies demonstrated that these compounds can inhibit the activity of the dual-target enzyme(SE/CYP51),and exert synergistic antifungal effects.Meanwhile,in vivo experiments showed that compounds 32 i and 37 i had significant antifungal activity and low toxicity.This part of the research shows that the new dual target antifungal inhibitors can be constructed efficiently by using fragment combination.In conclusion,this study provides a new design idea for discovery of antifungal drug and lays an important foundation for solving the problem of fungal resistance.