The root barks of Morus alba and the flavonoid constituents inhibit airway inflammation

Ethnopharmacological relevance The root barks of Morus alba have been used in traditional medicine as an anti-inflammatory drug, especially for treating lung inflammatory disorders. Aim of study To find new alternative agents against airway inflammation and to establish the scientific rationale of the herbal medicine in clinical use, the root barks of Morus alba and its flavonoid constituents were examined for the first time for their pharmacological activity against lung inflammation. Materials and methods For in vivo evaluation, an animal model of lipopolysaccharide-induced airway inflammation in mice was used. An inhibitory action against the production of proinflammatory molecules in lung epithelial cells and lung macrophages was examined. Results Against lipopolysaccharide-induced airway inflammation, the ethanol extract of the root barks of Morus alba clearly inhibited bronchitis-like symptoms, as determined by TNF-α production, inflammatory cells infiltration and histological observation at 200–400 mg/kg/day by oral administration. In addition, Morus alba and their major flavonoid constituents including kuwanone E, kuwanone G and norartocarpanone significantly inhibited IL-6 production in lung epithelial cells (A549) and NO production in lung macrophages (MH-S). Conclusions Taken together, it is concluded that Morus alba and the major prenylated flavonoid constituents have a potential for new agents to control lung inflammation including bronchitis.