Amantadine derivative Amt-1 enhances antiviral defense against influenza A virus via Nrf2/HO-1 pathway.

The rise of drug-resistant influenza A virus (IAV) strains and severe lung injury caused by excessive inflammation highlight the need for new antivirals that combine antiviral and immunomodulatory effects. Adamantane, an established anti-IAV agent, targets the viral M2 matrix protein, but widespread mutations have limited its clinical utility. Previously, we identified that 2,5-dihydroxybenzylalcohol and its derivatives possess anti-IAV activity. In this study, we synthesized a series of adamantane-2,5-dihydroxy-benzylalcohol derivatives via reductive amination. Among these, Amt-1 demonstrated strong antiviral activity against both amantadine-sensitive (H1N1 PR8) and clinical isolates IAV strains (-log IC₅₀ = 6.12-6.51 M). Mechanistic analyses, including immunofluorescence, isothermal titration calorimetry, quantitative polymerase chain reaction, ELISA, luciferase assays, and western blotting, revealed that Amt-1 not only interacts with the peptide segment of M2 ion channel protein (-log Kd = 5.08 M) but also activates nuclear factor erythroid 2-related factor 2, leading to increased heme oxygenase-1 expression and reduced production of proinflammatory cytokines interleukin-6, interleukin-1β, and tumor necrosis factor-α. Additionally, Amt-1 inhibited IAV-induced nuclear factor kappa-B activation, thereby suppressing viral replication. In vivo, Amt-1 reduced lung viral titers and mitigated histopathological damage in mice, surpassing amantadine in controlling inflammation and increased survival to 33%. In summary, Amt-1 is the first adamantane derivative shown to exert anti-IAV effects by modulating nuclear factor erythroid 2-related factor 2/heme oxygenase-1-mediated anti-inflammatory pathways and nuclear factor kappa-B-driven antiviral responses, while retaining M2 ion channel inhibition. This host-directed mechanism addresses drug resistance and limits immunopathology, making Amt-1 a promising therapeutic candidate for resistant influenza infections. SIGNIFICANCE STATEMENT: Amt-1 exhibits a dual mechanism of action, including direct antiviral effects through residual M2 affinity and host-directed anti-inflammatory activity mediated by the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 and nuclear factor kappa-B pathways. This balanced immunomodulatory and antiviral profile presents a distinct approach in adamantane-based drug development.