Screening for anti-inflammatory and bronchorelaxant activities of 12 commonly used Chinese herbal medicines.

The use of health supplements derived from medicinal herbs as self-medication for the relief of respiratory tract pathology symptoms is increasing in Chinese communities as air pollution is worsening. Twelve herbs from two formulae of our previous studies were evaluated for their anti-inflammatory, immunomodulatory and bronchorelaxant activities in this study. Among the extracts tested, those of Herba Schizonepetae and Radix Glycyrrhizae showed significant inhibitory effects on LPS-induced nitric oxide production (p < 0.05) in mouse macrophage RAW264.7 cells, suggesting their anti-inflammatory activities. Radix Scutellariae and Radix Glycyrrhizae extracts showed significant inhibitory effects on phytohaemagglutinin-induced proliferation in human peripheral blood mononuclear cells (p < 0.05). These extracts also showed inhibition of TNF-α, IFN-γ and IL-10 production. For the bronchorelaxant assay, Rhizoma Cynanchi Stauntonii and Radix Glycyrrhizae extracts showed potent attenuation of the acetylcholine- and carbachol-induced contractions in rat trachea (p < 0.05), implying their relaxant activities. In conclusion, Herba Schizonepetae, Radix Glycyrrhizae, Radix Scutellariae and Rhizoma Cynanchi Stauntonii extracts were demonstrated to exert anti-inflammatory, immunomodulatory and bronchorelaxant activities, which may help to ameliorate the symptoms of respiratory tract pathologies. The findings have thus provided some scientific evidence on the efficacy and mechanisms of action of these herbs, which are useful for the further development of clinical applications.