Tiger Milk Medicinal Mushroom Lignosus rhinocerus (Agaricomycetes) Polysaccharides Mediates Airway Smooth Muscle Relaxation via Muscarinic and Histamine Receptors

The medicinal and nutritional benefits of mushrooms have long been explored, with polysaccharides among the major bioactive constituents. Among these, <i>Lignosus rhinocerus</i> (tiger milk mushroom) is well documented for the traditional treatment of ailments, including respiratory illness, and has been shown to express several bioactivities, including anti-asthmatic effects. In this study, the polysaccharide constituents of <i>L. rhinocerus </i>mushroom were successfully extracted and fractionated using Soxhlet extraction, column chromatographic methods followed by cytotoxicity analysis. To test for its airway relaxation potential, an isolated guinea pig trachea (GPT) ring was used in a functional multichannel myograph study to evaluate the relaxation effects of <i>L. rhinocerus </i>polysaccharides (LRP) on muscarinic, histamine, and &beta;₂ airway receptor agonist-antagonist responses. The mushroom polysaccharides were found to be a neutral, water-soluble polysaccharide-protein complex, and the LR crude extract and its polysaccharides fraction showed no cytotoxic effect against the Vero cell line. LRP induced concentration-dependent relaxation in contracted airway smooth muscle, which was pre-contracted with EC₄₀ carbachol and EC₅₀ histamine. The airway relaxation effect of LRP is mediated via muscarinic and histamine receptors which supports the therapeutic potential of LRP as a natural alternative for the management of asthma.