Discovery Of Antiviral Lead Compounds Targeting Viral Capsid Proteins And Reverse Transcriptase

Acquired immunodeficiency syndrome(AIDS)and Hepatitis B are severe infectious diseases caused by the human immunodeficiency virus(HIV)and hepatitis B virus(HBV)respectively.These diseases are a global public health burden,causing a socio-economic situation.Many existing drugs are available to treat AIDS and HB V,but many lack a success rate due to drug resistance.Therefore,it is essential to discover the novel anti-HIV and anti-HBV inhibitors with superior pharmacological activity and favorable drug-like properties.It has been reported that capsid protein(CA)can interact with several host cell factors.Therefore,CA has been considered an attractive but underexploited target for clinical drug research.Also,reverse transcriptase(RT)inhibitors play a significant role in antivirus drug discovery.Thus,focusing on both capsid protein and reverse transcriptase targets,we designed and synthesized three series of novel compounds and evaluated them for their biological activity studies(1)Design,synthesis and preliminary druggability evaluation of the prodrug of HBV capsid protein inhibitor NVR 3-778HBV capsid protein(C A)is the vital structural protein of viral capsid,which plays an essential role in the viral life cycle and is necessary for maintaining the infectivity and stability of HBV.Therefore,HBV capsid protein has become an attractive target in the field of anti-HB V drugs.To improve the water solubility of HBV CA inhibitor NVR 3-778,in this chapter,we used a prodrug strategy to design and synthesize NVR 3-778 hemisuccinate prodrug 1-4.From the in vitro anti-HBV activity results,it was revealed that prodrug 1-4 inhibited HBV replication efficiently with the IC50 value of 0.246±0.058 μM,which is slightly better than NVR 3-778(IC50=0.40±0.13 μM).On the other hand,the water solubility of prodrug I-4 in three phosphate buffers at various pH levels(2.0,7.0,7.4)is superior and a hundred times better than the NVR 3-778.It is of great significance for the development of new dosage forms of NVR 3-778 prodrug.In addition,I-4 demonstrated excellent plasma and blood stability in vitro and good pharmacokinetic properties in rats.Finally,the hemisuccinate prodrug I-4 significantly improved the candidate drug NVR 3-778’s water solubility and increased metabolic stability while maintaining its antiviral efficacy.(2)Discovery of novel HIV-1 NNRTIs targeting the tolerant region IHIV-1 reverse transcriptase(RT)has substantial biochemical activities as RNA/DNA-dependent DNA polymerase and Ribonuclease H(RNase H)in the process of viral genome replication.It is considered to be the preferred target for the development of anti-AIDS drugs.Non-nucleoside reverse transcriptase inhibitors(NNRTIs)are widely used in anti-HIV-1 infection,owing to their promising antiviral potency,high specificity and low toxicity.However,there are some drawbacks such as drug resistance,severe adverse effects,and poor pharmacokinetics in their clinical application.In this chapter,to enhance the affinity with HIV-1 RT,improve the water solubility and other physicochemical properties,we introduced some hydrophilic groups rich in sp3 carbon atoms on the right-wing of etravirine(ETV,a representative second-generation NNRTI).All the synthesized target compounds exhibited positive activities against HIV-1 wild-type(WT)strain with EC50 values ranging from 0.16 to 0.0021 μM.Among all,II-7c displayed significantly higher antiviral potency than ETR against WT,K103N and E138K with relatively low cytotoxicity.Compared to ETR,II-7c showed improved water solubility and other drug-like properties with an increased Fsp3(Fraction of sp3 carbon atoms)value.Besides,the interaction of compound II-7c with HIV-1 RT was studied by molecular docking and molecular dynamics simulation.Overall,II-7c is a valuable structural compound for further investigation owing to its great antiviral potency and excellent drug-like properties.(3)Design,synthesis and antiviral evaluation of novel HIV-1 capsid protein inhibitorsAntivirals with a novel mechanism of action against underexploited HIV-1 targets are highly desirable to complement existing highly active antiretroviral therapy(cART)combinations,enabling persistent efficacy,especially against resistant mutants within current AIDS therapy.One such novel target is the HIV-1 capsid(CA)protein.The HIV-1 CA protein is crucial in early-and late-stage viral replication cycle events,essential for virus infectivity.PF-74 is a small molecule HIV-1 inhibitor and achieved great significance in HIV drug discovery due to its unique mechanism action.This chapter reported the design,synthesis,and antiviral evaluation of a series of novel PF-74 derivatives based on their binding mode with the action site.The results showed that the change of linker and substituents targeting the CA C-terminal domain(CTD)greatly influenced the antiviral activities.Most of the compounds from series III-b and III-e showed moderate antiviral activities,while the other compounds lost the ability to inhibit HIV-1 replication at the tested concentration.Among the tested series,III-b3(EC50=5.14±1.62 μM)and III-e10(EC50=2.57±0.79 μM)displayed the best anti-HIV-1 potency,but their activities were slightly lower than that of PF-74(EC50=0.42±0.11 μM).Besides,Surface plasmon resonance(SPR)analysis showed that III-b3 and III-e10 tended to combine with CA hexamer rather than monomer.Moreover,molecular dynamics simulation and molecular docking studies were applied to explore the interactions of III-b3 and III-e10 with capsid protein.In short,this work provides valuable insights to design more potent HIV-1 CA inhibitors further.Taken together,we discovered a batch of lead compounds with excellent antiviral activity and promising drug-like properties by viral capsid proteins and reverse transcriptase.From this thesis:the hemisuccinate prodrug I-4 significantly improved the water solubility and metabolic stability of the candidate drug NVR 3-778;compared to positive drug ETR,the novel NNRTI Ⅱ-7c demonstrated outstanding antiviral potency and favourable physicochemical properties;taking PF-74 as a lead compound,we discovered novel HIV-1 CA inhibitors III-b3 and III-e10.This work contributes to developing innovative antiviral drugs with high efficiency,low toxicity,and good druggability.