Qstatin

Qstatin (CAS No.: 902688-24-8) is a small-molecule quorum sensing inhibitor that selectively targets SmcR, a LuxR homolog in Vibrio harveyi, functioning as a key transcriptional regulator in bacterial cell–cell communication pathways. This compound binds tightly to SmcR and modulates its conformational flexibility, thereby disrupting its ability to regulate downstream gene expression associated with quorum sensing. Qstatin exhibits potent activity in the nanomolar range, with an EC50 of approximately 208.9 nM, and has also been shown to inhibit LuxR-dependent reporter activity at micromolar concentrations in biochemical assays. It demonstrates broad-spectrum, pan-quorum sensing inhibitory effects across multiple Vibrio species, leading to attenuation of virulence phenotypes in aquatic host models. As a result, Qstatin is widely used in studies of bacterial communication, virulence regulation, and anti-infective strategy development, particularly in the context of antivirulence approaches that avoid direct bactericidal pressure. In experimental settings, its application spans cell-based assays, reporter gene systems, and in vivo infection models, with concentrations or dosing regimens adjusted according to specific research objectives.