Pharmacokinetic Study Of Anti-influenza Candidate Compound 15b And Design,synthesis And Biological Evaluation Of Novel HIV-1 Capsid Protein Inhibitors

Part 1:Pharmacokinetic study of anti-influenza candidate compound 15bInfluenza is an acute upper respiratory tract infectious disease caused by influenza virus,which has caused serious harm to human health.Influenza virus is characterized by its relatively high morbidity and fatality rate.Therefore,it is imperative to focus on potential targets and use rational drug design strategies to develop anti-influenza drugs with independent intellectual property rights.Based on our detailed and in-depth study of influenza neuraminidase inhibitors,we have obtained 15b with excellent enzyme inhibitory activity and in vitro antiviral activity.It exhibited prominent inhibitory activity on Group-1 and Group-2 neuraminidase,potent inhibitory activity on H274Y and E119V mutants and better antiviral activities on H5N1,H5N2,H5N6 and H5N8 than the lead compound OSC.However,the oral bioavailability of compound 15b is only 3.70%;the biological half-life is also short,0.32 h(iv)and 5.22 h(po),respectively.Besides,the oral bioavailability of OSC is 4.3%;the oral biological half-life of OSC is 10.6 h.The disadvantages of pharmacokinetic properties severely limit the clinical application of 15b.Therefore,to improve its pharmacokinetic properties and increase its druggability,this project conducted further research on 15b through salt formation strategy.Initially,we screened 15b organic acid salts and inorganic acid salts based on many literature investigations.Comprehensively compared the crystal forms and stability of various salt compounds,and finally screened out phosphates of 15b and performed the elemental analysis and pharmacokinetic study in rats.Elemental analysis result indicated that 15b can be combined with three phosphoric acids.From the pharmacokinetic results in rats,surprisingly,it was noticed that the oral bioavailability decreased from 3.70%to 0.29%after phosphate formation,and the intravenous biological half-life decreased from 0.32 h to 0.19 h.It is speculated that it may have intestinal stability or membrane permeability problems,leading to unsatisfactory bioavailability.Although the above experimental results did not meet the expected goals,they also provided valuable insights to the clinical development of anti-influenza candidate compound 15b.Part 2:Design,synthesis and activity evaluation of a novel HIV-1 capsid protein inhibitorAIDS,also known as acquired immune deficiency syndrome,has become an infectious disease that seriously threaten human health and life.The AIDS epidemic situation is not optimistic,and the status of prevention and control is very bleak!Therefore,it is urgent to further study the life cycle and pathogenesis of HIV-1 to develop new anti-AIDS drugs with better efficacy,fewer side effects and favourable anti-drug-resistance profile.Capsid protein(CA)plays a vital biological role in both the early and late stages of HIV-1 replication.Unfortunately,there is no marketed drug currently for this target.Due to the unsatisfactory antiviral activity or poor druggability of the existing HIV-1 capsid protein inhibitors,the development of safe,effective and well-tolerated HIV-1 capsid protein inhibitors is still one of the important directions in the research and development of anti-AIDS drugs.Based on the target structure of HIV-1 capsid protein and its co-crystal complex structure with PF74,we employ PF74 as the lead compound,designed and synthesized three series of 72 target compounds with novel structures by target-based drug design strategy and ligand-based drug design strategy.Unfortunately,48 compounds modified by the target-based drug design strategy lost their antiviral activity.Analyzed the reasons for the loss of antiviral activity,and we can get some lessons:(1)The optimization of the linker of PF74 should try to maintain or add more donors or receptors of hydrogen bonds;(2)We can try to introduce more hydrophilic atoms or groups in the indole ring of PF74;(3)For the inhibitors of protein-protein interaction,the larger the contact area with the target,the more favorable it is to form a stronger interaction.Therefore,further structural optimization can appropriately expand the spatial structure of the target compounds,increase their affinity to the target,and thereby improve their antiviral activity.However,it is worth noting that 24 compounds modified by the ligand-based drug design strategy showed good anti-HIV activity.Although the anti-ⅢB strain activity of this series of compounds did not exceed the lead compound PF74(EC50=0.75±0.14μM,SI=42),there were two compounds LA-6q and LA-6t that showed a single-digit micromolar level of antiviral activity with an EC50 value of 3.57±0.15 μM(SI=16)and 5.02±1.0 μM(SI=27),respectively.Besides,two of them(LA-6r and LA-6t)exhibited the best antiviral activity against ROD strains,with EC50 of 1.55±0.32 μM(SI=86)and 0.85±0.24 μM(SI=157),respectively.Compared to PF74(EC50=4.16±0.86 μM,SI=8),the antiviral activity of LA-6r and LA-6t against HIV ROD increased by 2.5 times and 4.9 times,respectively;the SI increased by 10.8 times and 19.6 times,respectively.Besides,the preliminary evaluation results of druggability showed that LA-6q and LA-6t showed higher metabolic stability in human liver microsomes and human plasma.The biological half-life of LA-6q and LA-6t in human liver microsomes was increased by 109.2 times and 51.4 times than PF74,respectively;the results of human plasma stability showed that after incubation with human plasma for 120 min,the remaining amounts of LA-6q and LA-6t were 98.7%and 106.8%,respectively.This part of the work has laid a solid foundation for developing HIV-1 capsid protein inhibitors with better antiviral activity and high selectivity.