title: In vitro anti-influenza virus activity of synthetic humate analogues derived from protocatechuic acid.
abstract: Two humic-like substances, the oxidative polymer of protocatechuic acid (OP-PCA) and humic acid inhibit the in vitro replication of influenza virus A/WSN/33 (H1N1) in Madin-Darby canine kidney (MDCK) cells at concentrations of no cytotoxicity. The 50% inhibitory concentration (IC50) for OP-PCA was 6.59 +/- 1.02 microg/ml when the compound was added at the stage of viral adsorption. When OP-PCA was added after virus adsorption, the IC50 was 53.27 +/- 8.12 microg/ml. The IC50 for humic acid was 48.61 +/- 7.32 microg/ml and 55.27 +/- 5.46 microg/ml respectively when the compound was added at the stage of viral adsorption or post-adsorption. In spite of structural resemblance of these two compounds, they exhibit different actions of anti-flu. The OP-PCA inhibits virus-induced hemagglutination and low pH-induced cell-cell fusion. Humic acid inhibits the endonuclease activity of viral RNA polymerase. The monomer of PCA shows no inhibition on influenza virus replication.
authors.affiliation: Department of Biochemistry, College of Medicine, National Taiwan University, Taipei.
authors.forename: F J
authors.initials: FJ
authors.lastname: Lu
authors.forename: S N
authors.initials: SN
authors.lastname: Tseng
authors.forename: M L
authors.initials: ML
authors.lastname: Li
authors.forename: S R
authors.initials: SR
authors.lastname: Shih
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D004720:Endonucleases / Q000187:drug effects / Q000378:metabolism; D006812:Humic Substances / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D062385:Hydroxybenzoates / Q000737:chemistry / Q000494:pharmacology*; D009980:Influenza A virus / Q000187:drug effects* / Q000254:growth & development; D007668:Kidney / Q000166:cytology; D010084:Oxidation-Reduction; D011108:Polymers / Q000494:pharmacology*; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D006812:Humic Substances; D062385:Hydroxybenzoates; D011108:Polymers; D014764:Viral Proteins; C009091:protocatechuic acid; D004720:Endonucleases