# An Imidazo[2,1‐b][1,3,4]thiadiazole Derivative Inhibits the Virulence Factor α‐Hemolysin by Blocking the Pullout of Its Stem Domain

## TL;DR

A new thiadiazole compound was found to block a key toxin in Staphylococcus aureus, potentially offering a new treatment strategy for infections.

## Contribution

A novel thiadiazole chemical class was identified as an antivirulence agent against Staphylococcus aureus.

## Key findings

- A high-throughput assay identified thiadiazole-based inhibitors of α-hemolysin with up to 5.4 µM potency.
- X-ray crystallography showed thiadiazole binds to a hydrophobic pocket in α-hemolysin, blocking stem loop unfolding and membrane attachment.
- Thiadiazoles represent a new chemical class for antivirulence therapeutics against S. aureus.

## Abstract

Staphylococcus aureus is a major human pathogen responsible for severe infections that necessitate alternative therapeutic strategies. Its key virulence factor α‐hemolysin (Hla) mediates host cell damage via pore formation, making it an attractive target for antivirulence interventions. Here, we report the development of a high‐throughput cellular assay measuring toxin‐induced calcium influx. Its application led to the identification of thiadiazole‐based small molecule inhibitors of Hla. Structure–activity relationship studies with 18 analogs led to inhibitors with a cellular potency up to 5.4 µM. X‐ray crystallography of Hla in complex with compound 1 revealed that the thiadiazole bound a hydrophobic pocket at the interface of the amino latch and prestem domains, exerting a dual mechanism that blocks stem loop unfolding as well as membrane attachment. These findings introduce thiadiazoles as a novel chemical class of antivirulence therapeutics against S. aureus infections.

A high‐throughput cellular screen based on Ca2+ influx in U937 monocytic cells identified thiadiazoles as small‐molecule inhibitors of α‐hemolysin, a key virulence factor of Staphylococcus aureus. The thiadiazole 1 prevents pore formation by a dual mechanism that prevents stem loop unfolding as well as membrane attachment.© 2026 WILEY‐VCH GmbH