Discovery Of Novel Anti-infective Drugs And The Research Of Their Molecular Mechanism

During the time of fighting aginst diseases,scientists have made great achievements in the research of anti-infective drugs,including various drugs against bacteria,viruse,tuberculosis,parasites and other pathogens.The targets of anti-infective drugs are mainly concentrated on the components of pathogenic microorganisms,including key molecules in pathogen metabolism,cell wall components,biochemical enzymes,drug enzymes,and receptor molecules.At present,anti-infective drugs have single targets and clear mechanisms.Drug-resistant problems arise when the microbe undergo genetic variation in unfavorable environment(such as mutations in drug targets).Drug-resistant is a major challenge for anti-infective treatment globally.The research of anti-infective drugs is still a continuous process.Preparing for new challenges,the exploration of new medical targets,chemical skeletons and combinational drugs methods are essential.In this article,we mainly focused on anti-Zika virus drugs and anti-tuberculosis drugs.We established screening models for anti-Zika virus drugs and anti-tuberculosis drugs.By screening compound libraries,we identified the lead compounds with anti-Zika virus and anti-tuberculosis activity.Meanwhile,we assay the mechanism of the newly discovered compounds.Part I:The research of anti-Zika virus drugs targeting at NS5 RdRp protein.Zika virus(ZIKV)is an important human mosquito-borne virus in the Flaviviridae family,which can cause severe neurological complications and congenital malformation.The explosive spread of ZIKV has exacerbated the urgency of anti-ZIKV drugs development.ZIKV non-structural protein 5(NS5)RNA-dependent RNA polymerase(RdRp)is essential for viral replication and is logically regarded as an attractive drug target.RdRp catalyzes the synthesis of RNA strands which is the most important step in viral replication.In this study,We used a fluorescence-based polymerase assay to establish a ZIKV NS5 RdRp inhibitor screening model.UA,an anti-infective drug,could inhibit ZIKV NS5 RdRp activity with an IC50 of 1.13 ?M.At the same time,sofobuvir triphosphate(PSI-7409),an active product of sofobuvir,was used as a control.We found that PSI-7409 conferred insensitivity to RdRp activity assay.Molecular docking and site-directed mutagenesis analyses identified D535 as the key amino acid in the interaction between ZIKV NS 5 RdRp and the UA.Importantly,the SPR assay showed that UA had a strong direct binding with ZIKV NS 5 WT-RdRp and a relatively weak interaction with D535A-RdRp.At the same time,it was found that PSI-7409 cannot bind directly with RdRp.UA showed good antiviral activity.All these results indicate that UA is likely to be a promising lead compound against ZIKV,exhibiting a different mechanism than sofosbuvir.Part II:The research of anti-tuberculosis drugs targeting FtsZ protein.Recent years,with the emergence of multi-drug resistant(MDR)Mycobacterium tuberculosis(TB)and co-infection,tuberculosis treatment is facing a big challenge.Discovering high-efficiency and low-toxic anti-tuberculosis drugs is the key to solving the problem of tuberculosis.Filamentous temperature sensitive protein Z(FtsZ),a GTP dependent prokaryotic cell division protein,forms a dynamic Z-ring in the center of the cell.Differences between bacterial FtsZ and eukaryotic tubulin make FtsZ a highly attractive drug target.Targeting M.tuberculosis FtsZ(Mtb-FtsZ),we used phenotypic screening of M.smegmatis and model screening to identify a hit compound 146E12.146E12 was found to prevent the growth of M.smegmatis by inhibiting the GTPase activity and the polymerizate function of Mtb-FtsZ.Molecular docking and site-directed mutagenesis analyses identified Asn22 of Mtb-FtsZ as the key amino site.The higher MIC of 146E12 for M smegmatis strain overexpressing Mtb-FtsZ confirmed that Mtb-FtsZ is likely the target.Compared with isoniazid and rifampicin,the first-line anti-tuberculosis drugs,146E12 exhibits excellent activity against MDR-TB and XDR-TB.At the same time,146E12 has no anti-bacterial activity to other strains.Moreover,the drug susceptibility test shows that 146E12 is much less toxic to eukaryotic cells.All these results indicate 146E12 is a promising lead compound against drug-resistant tuberculosis.