Ultrapure and potent tannic acid as a pluripotent protease and influenza HA inhibitor against influenza virus infection
Creators: name: Shih, Tsai-Miao
name: Hsieh, Han-Yi
name: Hu, Jhe-Wei
name: Wu, Yu-Jung
name: Kuo, Chi-Sheng
name: Lu, Lu-Ping
name: Lai, Yi-An
name: Chou, Teh-Ying
name: Tsai, Guochuan Emil
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Biochemistry
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Pharmacology
subject: Biotechnology
subject: Chemical Sciences not elsewhere classified
subject: Immunology
subject: FOS: Clinical medicine
subject: Biological Sciences not elsewhere classified
subject: Cancer
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Virology

description: <b>Background:</b> Influenza viruses are fast-spreading respiratory pathogens that threaten public health and pose a colossal burden to the healthcare system. Current medications targeting viral enzymes struggle against resistant strains. Several human proteases mediate the proteolytic activation of viral hemagglutinin, whose cleavage is critically essential to virus penetration and propagation. Inhibiting these host proteases is thus a promising approach to prevent drug resistance. <b>Materials &amp; methods:</b> We identified Pentarlandir<sup>®</sup> ultrapure and potent tannic acid (UPPTA) as a versatile antiviral against host proteases crucial for influenza infection, the human airway trypsin-like protease as well as transmembrane serine protease 2 (hTMPRSS2) and even the viral neuraminidase. <b>Results:</b> Pentarlandir<sup>®</sup> UPPTA inhibited the infection of circulating influenza viruses at sub-micromolar concentrations <i>in vitro</i>, including oseltamivir-resistant strains. Additionally, Pentarlandir<sup>®</sup> UPPTA synergistically inhibited influenza viruses with oseltamivir carboxylate, showing excellent drug combination index and drug reduction index. Importantly, in a virus-challenged mice model, Pentarlandir<sup>®</sup> UPPTA ameliorated infection-induced body weight loss and increased survival by halting infection-induced cytokine overproduction and subsequent lung damage. <b>Conclusion:</b> Taken together, with its virucidal activity against SARS-CoV2 virus, Pentarlandir<sup>®</sup> UPPTA’s antiviral activity makes it a potential candidate against respiratory infections and an important player in the era of twindemic. Influenza’s burden necessitates new treatments due to drug-resistant variants evading traditional neuraminidase-targeting medications. Pentarlandir<sup>®</sup> ultrapure and potent tannic acid (UPPTA), a tannic acid formulation, is investigated for its antiviral activity against viral entry related host proteases (human type II transmembrane serine proteases) and influenza viruses. Pentarlandir<sup>®</sup> UPPTA’s antiviral effects were tested against influenza proteins and host proteases involved in viral entry, along with cell viability assays. An <i>in vivo</i> mouse model assessed Pentarlandir<sup>®</sup> UPPTA’s efficacy against influenza A virus (IAV) infection by monitoring survival, viral load, inflammation and lung damage. Dose-dependent retardation in gel mobility of recombinant IAV HA1 subunit was observed upon incubation with Pentarlandir<sup>®</sup> UPPTA, suggesting its potential binding to the HA1 domain. Pentarlandir<sup>®</sup> UPPTA exhibited superior inhibitory activity against influenza virus neuraminidase and host proteases (hTMPRSS2, HAT) compared with a commercial tannic acid, demonstrating its potential for influenza treatment. Pentarlandir<sup>®</sup> UPPTA showed minimal inhibition of human proteases (thrombin, cathepsin B, cathepsin E) at concentrations exceeding potential therapeutic doses, suggesting good specificity. Pentarlandir<sup>®</sup> UPPTA effectively reduced viral RNA load (EC<sub>50</sub> 0.16–1.94 μM) in various influenza strains (A/H1N1, A/H3N2, B/Victoria, B/Yamagata) with high selectivity index (60.91–747.47) in cell culture, including oseltamivir-resistant H1N1. In addition to its independent antiviral activity, Pentarlandir<sup>®</sup> UPPTA showed synergistic effects when combined with oseltamivir carboxylate against IAVs (H1N1, H3N2), potentially improving treatment efficacy. Pentarlandir<sup>®</sup> UPPTA at 450 mg/kg/day effectively reduced viral load, lessened inflammatory response and protected lung tissue in a mouse model of influenza A infection, exhibiting potential therapeutic benefits. The mechanisms underlying the inhibitory activities of Pentarlandir<sup>®</sup> UPPTA may be attributed to the serine/cysteine-based proteolysis inhibition, rather than dual aspartate-mediated proteolysis. Pentarlandir<sup>®</sup> UPPTA showed synergistic efficacy with oseltamivir carboxylate (Tamiflu) in IAV virucidal assays, potentially enable lower drug doses, reducing pill burden and potential side effects. Pentarlandir<sup>®</sup> UPPTA exhibited antiviral activity against influenza viruses <i>in vitro</i> and <i>vivo</i> by targeting both viral and host mechanisms, making it a promising candidate against existing and future strains.