Structure-based Design,Synthesis And Bioactivity Evaluation Of Novel HIV-1 Integrase Inhibitors And RNase H Inhibitors

AIDS,mainly caused by HIV-1 infection,has become serious threats to human health and life.Currently,30 anti-HIV-1 chemical entities were approved by U.S.FDA for HIV-1 clinical therapy.Although the application of highly active antiretroviral therapy(HAART)greatly reduced the incidence and mortality of AIDS,its efficiency can be strongly limited by the emergence of extensively cross-resistant strains and the adverse effects of long-term use of these drug regimens.Therefore,there is still an urgent need for anti-HIV drug candidates,particularly for those acting on novel targets or showing mechanisms of action different from those used by currently approved drugsHIV-1 integrase(IN)is an essential enzyme in the life cycle of virus,which catalyzes the integration of HIV-1 DNA into host cell DNA.Although four IN strand transfer inhibitors have been approved,with the emergence of resistant mutants of HIV IN,it is vital to develop novel IN inhibitors with potent antiviral activity and anti-resistant profile.HIV-1 RNase H plays an important role in viral replication and is a potentially important and underexploited target for designing novel anti-HIV drugs.Since most of RNase H active site inhibitors discovered currently show low antiviral activity,poor membrane permeability and high cellular cytotoxicity,HIV RNase H inhibitors have not been approved for clinical use.Hence,the discovery of potent and specific HIV-1 RNase H inhibitors is critically needed.HIV-1 IN and RNase H domain on RT belong to the same protein superfamily-metalloprotein.The presence of catalytically active metal ions severely limits the application of molecular docking in structure-baesd drug design.Meanwhile,privileged structure-based drug design has become an effective method for drug discovery.In view of these,we explored novel HIV-1 IN inhibitors and RNase H inhibitors based on the target structure and combined with the privileged scaffold.Design,synthesis and bioactivity evaluation of novel 8-hydroxy-1,6-diazaphthalen derivatives as HIV-1 INSTIs.The para position of the metal chelating motif in INSTIs could accommodate large groups,which might form additional interactions with IN,increase IN inhibition activity and improve drug resistance profiles.8-hydroxy-1,6-naphthyridine is a privileged scaffold worthy of further optimization.The substituent modification of this kind of skeleton was mostly focused on the "lateral position" of metal chelating motif,while the new INSTIs 60 discovered by Long’s group proved the feasibility of large group modification in the para position of metal chelating motif.The highly effective pyridopyrimidinone INSTIs found in our group also strongly support this design.Thus,we selected 8-hydroxy-1,6-diazanaphthalene as skeleton and introduced a variety of aromatic hydrophobic groups in the para position of metal chelating motif.A series of 20 novel 8-hydroxy-1,6-naphthyridine derivatives were synthesized.The results of enzyme inhibition showed that four target compounds(I-4,I-6,I-7 and I-20)had moderate inhibitory activity against IN.The inhibitory activity of the best compound I-6(IC50 =1.46±0.13 μM)was closest to that of RAL(IC50 = 0.77±0.33 μM).All compounds showed no inhibition against RNase H(IC50>50 μM),indicating that these compounds are selective IN inhibitors.The anti-HIV activity results showed that two target compounds(I-11 and I-18)exhibited weak anti-HIV-1 activity.Cell permeability tests showed that the weak permeability of the compounds is a possible factor affecting their activity against HIV-1.We selected I-6 for molecular dynamics simulation study and found that the strong binding ability to IN Y212 and Q186 is essential for its efficient and selective inhibition of HIV-1 IN.In conclusion,this series of compounds explored the new tolerant region of INSTIs,enriched the SAR of INSTIs,and laid the foundation for the discovery of novel and efficient HIV-1 IN inhibitors.Design,synthesis and bioactivity evaluation of novel pyridinopyrimidinone derivatives as HIV-1 RNase H inhibitors.Based on untapped binding sites of RNase H,we selected priviledged structure with metal-chelating ability,and carried out systematic modification of side chain to occupy its favorable sites,which might lead to the discovery of novel and highly effective HIV-1 RNase H inhibitors.Besides,Wang’s group discovered a novel series "double-winged" RNase H inhibitors with anti-HIV activity by using "group addition" strategy.Inspired by this,we selected the pyridopyrimidinone scaffold in the cell-active HIV-1 IN inhibitor 30 discovered by our group,and introduced the hydrophobic group of the RNase H inhibitors at the C4 and C6 position for improving the binding ability to RNase H,reducing the polarity and increasing membrane permeability.A series of 14 new pyridopyrimidinone derivatives were synthesized.The results of RNase H inhibition showed that activity of the seven target compounds exceeded β-thujaplicinol(IC50 = 1.98±0.22 pM),and II-9 showed the best inhibitory activity,reaching 0.54 ± 0.27μM.Molecular simulation showed that the left wing of II-9 formed double hydrogen bonds with RNase H S499 and Y501,and the right wing formed strong hydrophobic interaction with N474,which may be the key to its effective inhibition of HIV-1 RNase H.In summary,this series of compounds provides a guidance for the optimization of subsequent RNase H inhibitors.In addition,the IN inhibitory activity test and cell-based anti-HIV activity test are under progress.