Synthesis And Anti-influenza Study Of Oleanolic Acid-polymaleic Acid Conjugate

The effectiveness of the vaccine had been steadily reduced by the rapid mutation of influenza strains and the intercombination of multiple different types of genome fragments that made the virus resistant to existing antiviral drugs.Therefore,it was urgent to design and develop new influenza inhibitors.Hemagglutinin(HA)trimer structure was abundant on the surface of influenza virus and played an important role in the initial adhesion stage of the invasion of host cells by influenza virus.The development of inhibitors of HA could effectively solve the problem of drug resistance.The synthesis of oleanolic acid-polymaleic acid conjugate(OA-PM),which could inhibit influenza virus,was simple and efficient.In the previous work,our group proved that the pegylated oleanolic acid(OA)could increase biocompatibility,and the connection of oleanolic acid monomer(OA-NH2)with mucin could improve the anti-influenza activity of the monomer through the multivalent effect.The activity was increased by 20 times,but it was not greatly improved.In this work,we used maleic anhydride as a polymer skeleton to connect it with OA-NH2 through amide bond to further improve the anti-influenza activity of oleanolic acid monomer.Hemagglutination inhibition experiment,cytopathic effect experiment,surface plasmon resonance(SPR)experiment and isothermal titration calorimetry(ITC)experiment showed that OA-PM could enhance the affinity between OA-NH2 and HA through the multivalent effect,indicating that OA-PM could closely bind to HA on the surface of virus.In order to study the mechanism of its action on influenza virus,we applied time-of-addition experiment,neuraminidase inhibition experiment and dynamic light scattering(DLS)experiment.The experimental results showed that conjugates could cause the aggregation of viruses and inhibit the early adhesion and late release of influenza virus into host cells.The above experimental results show that OA-PM could effectively inhibit influenza virus from infecting host cells.It could be used in the design of antiviral drugs and the development of antiviral materials in the future.