Scutellaria barbata ameliorates acute respiratory distress syndrome by inhibiting neutrophil-mediated inflammatory responses

Ethnopharmacological relevance: The traditional medicinal herb Scutellaria barbata D. Don (commonly known as Ban Zhi Lian) is renowned for its heat-clearing and detoxifying properties and has been used to treat inflammatory conditions and various cancers. While lung inflammation is an indication for S. barbata, its effects on acute respiratory distress syndrome (ARDS) remain unclear. Aim of the study: Dysregulated neutrophilic inflammation plays a critical role in the pathogenesis of ARDS. In this study, we aimed to investigate the novel application of S. barbata in treating neutrophilic inflammation and ARDS. We evaluated the therapeutic potential of the ethanol extract of S. barbata (SB-EtOH) in mitigating neutrophil-driven inflammatory responses. Materials and methods: The chromatographic fingerprint of SB-EtOH was analyzed, and its ethnopharmacological mechanisms were examined for their effects on inflammatory responses in human neutrophils. The therapeutic potential of SB-EtOH was further assessed using a mouse model of lipopolysaccharide (LPS)-induced ARDS. Results: SB-EtOH significantly inhibited respiratory burst, degranulation, and chemotactic responses in activated human neutrophils without cytotoxic effects. Additionally, SB-EtOH attenuated phosphorylation of key inflammatory signaling molecules, Akt and p38, while reducing calcium mobilization in activated human neutrophils. In the LPS-induced ARDS mouse model, SB-EtOH reduced pulmonary neutrophil infiltration, lung tissue damage, and oxidative stress accumulation.