Development of Novel Anti-influenza Thiazolides with Relatively Broad-spectrum Antiviral Potentials.

Zhao, Lei; Yan, Yunzheng; Dai, Qingsong; Li, Xingzhou; Xu, Ke; Zou, Gang; Yang, Keyu; Li, Wei; Guo, Xiaojia; Yang, Jingjing; Li, Yuexiang; Xia, Qing; Cao, Ruiyuan; Zhong, Wu

Seasonal and pandemic influenza causes 650,000 deaths annually in the world. The emergence of drug-resistance to specific anti-influenza drugs such as oseltamivir and baloxavir marboxil highlights the urgency of novel anti-influenza chemical entity discovery. In this study, we report a series of novel thiazolides derived from an FDA-approved drug nitazoxanide with antiviral activity against influenza and a broad range of viruses. The preferred candidates 4a and 4d showed significantly enhanced anti-influenza potentials with 10-fold improvement, compared with nitazoxanide, and were effective against a variety of influenza subtypes including oseltamivir-resistant strains. Notably, the combination using of compounds 4a/4d and oseltamivir carboxylate or zanamivir displayed synergistic antiviral effect against oseltamivir-resistant strain. Mode of action analysis demonstrated that compounds 4a/4d acted at the late phase of viral infection cycle through inhibiting viral RNA transcription and replication. Further experiments showed that treatment with compounds 4a/4d significantly inhibited influenza virus infection in human lung organoids, suggesting the druggability of the novel thiazolides. In-depth transcriptome analysis revealed a series of up-regulated cellular genes that may contribute to the antiviral activities of 4a/4d Together, our study pointed the optimization direction of nitazoxanide as anti-influenza drug, and discovered two novel-structured candidates 4a/4d with relatively broad-spectrum antiviral potential.