title: Synthesis and in vitro study of novel neuraminidase inhibitors against avian influenza virus.
abstract: Evidences of oseltamivir resistant influenza patients raised the need of novel neuraminidase inhibitors. In this study, five oseltamivir analogs PMC-31-PMC-36, synthesised according to the outcomes of a rational design analysis aimed to investigate the effects of substitution at the 5-amino and 4-amido groups of oseltamivir on its antiviral activity, were screened for their inhibition against neuraminidase N1 and N3. The enzymes used as models were from the avian influenza A H7N1 and H7N3 viruses. The neuraminidase inhibition assay was carried out by using recombinant species obtained from a baculovirus expression system and the fluorogenic substrate MUNANA. The assay was validated by using oseltamivir carboxylate as a reference inhibitor. Among the tested compounds, PMC-36 showed the highest inhibition on N1 with an IC(50) of 14.6±3.0nM (oseltamivir 25±4nM), while PMC-35 showed a significant inhibitory effect on N3 with an IC(50) of 0.1±0.03nM (oseltamivir 0.2±0.02nM). The analysis of the inhibitory properties of this panel of compounds allowed a preliminary assessment of a structure-activity relationship for the modification of the 4-amido and 5-amino groups of oseltamivir carboxylate. The substitution of the acetamido group in the oseltamivir structure with a 2-butenylamido moiety reduced the observed activity, while the introduction of a propenylamido group was well tolerated. Substitution of the free 5-amino group of oseltamivir carboxylate with an azide, decreased the activity against both N1 and N3. When these structural changes were both introduced, a dramatic reduction of activity was observed for both N1 and N3. The alkylation of the free 5-amino group in oseltamivir carboxylate introducing an isopropyl group seemed to increase the inhibitory effect for both N1 and N3 neuraminidases, displaying a more pronounced effect against N1.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330, Thailand.
authors.forename: Jarinrat
authors.initials: J
authors.lastname: Kongkamnerd
authors.forename: Luca
authors.initials: L
authors.lastname: Cappelletti
authors.forename: Adolfo
authors.initials: A
authors.lastname: Prandi
authors.forename: Pierfausto
authors.initials: P
authors.lastname: Seneci
authors.forename: Thanyada
authors.initials: T
authors.lastname: Rungrotmongkol
authors.forename: Nutthapon
authors.initials: N
authors.lastname: Jongaroonngamsang
authors.forename: Pornchai
authors.initials: P
authors.lastname: Rojsitthisak
authors.forename: Vladimir
authors.initials: V
authors.lastname: Frecer
authors.forename: Adelaide
authors.initials: A
authors.lastname: Milani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cattoli
authors.forename: Calogero
authors.initials: C
authors.lastname: Terregino
authors.forename: Ilaria
authors.initials: I
authors.lastname: Capua
authors.forename: Luca
authors.initials: L
authors.lastname: Beneduce
authors.forename: Andrea
authors.initials: A
authors.lastname: Gallotta
authors.forename: Paolo
authors.initials: P
authors.lastname: Pengo
authors.forename: Giorgio
authors.initials: G
authors.lastname: Fassina
authors.forename: Stanislav
authors.initials: S
authors.lastname: Miertus
authors.forename: Wanchai
authors.initials: W
authors.lastname: De-Eknamkul
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D001665:Binding Sites; D001717:Birds / Q000821:virology; D057916:Influenza A Virus, H7N1 Subtype / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D057920:Influenza A Virus, H7N3 Subtype / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D009980:Influenza A virus / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D005585:Influenza in Birds / Q000188:drug therapy* / Q000201:enzymology; D008958:Models, Molecular; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D053139:Oseltamivir / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir; D009439:Neuraminidase