Publication: Anti-asthmatic and airway smooth muscle relaxation effects of polysaccharides from lignosus rhinocerotis in animal models
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Date
2025-05
Authors
Daku, Abubakar Bishir
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Abstract
Asthma is a chronic airway disease which is associated with several
characteristics including bronchoconstriction, airway vasodilation, oedema, sensory
nerve activation, and hypersensitivity. Systemic corticosteroids are crucial for
managing moderate-to-severe asthma but are associated with various adverse effects
with long-term use. This has driven researchers to explore safer complementary and
alternative anti-asthmatic interventions to mitigate these exaggerated immune
responses. Mushroom polysaccharides (MP) have been reported to contain β-glucan
compounds and polysaccharide-protein complexes, which are known to exhibit several
bioactivities, including anti-inflammatory, immunomodulatory, antitumor, and
antioxidant properties, as demonstrated in numerous in vivo and in vitro studies.
However, the potential of inhaled Lignosus rhinocerotis polysaccharide (LRP) to
ameliorate asthma pathophysiology remains undetermined, and current research on its
bioactive properties is limited. Therefore, this study aimed to (i) isolate and determine
the polysaccharide composition of LR mushrooms, (ii) determine LRP inhalation
delivery, (iii) establish a BALB/c mouse model of OVA-challenged allergic asthma
and determine the effect of LRP on asthma pathophysiology, and (iv) determine the
effect of LRP on airway receptor contractility in guinea pig tracheal (GPT) rings. The
LRP DEAE-cellulose and Sephadex G-100 column elution exhibited a single
symmetrical peak fractionated polysaccharide fraction. The megazyme β-glucan assay
revealed that the percentages of α- and β-glucans in LRP were 21.52% (±0.53) and 21.07% ± (2.19), respectively. HPLC analysis revealed that LRP was a typical
heteropolysaccharide composed of mannose, ribose, rhamnose, glucose, galactose,
xylose, and arabinose. LRP spray drying was shown to produce unstable LRP powders
due to its volatility and hygroscopic nature. Nebulization of the LRP solution-produced
inhalable aerosols for lung delivery, the in vitro aerosol deposition using NGI
demonstrated fine particle fraction (FPF) of 62.84, mean median aerodynamic
distribution (MMAD) of 4.16, and geometric standard deviation (GSD) of 1.83. LRP
nebulization treatment (4, 8, and 40 mg/ml) in an OVA-challenged mouse model of
asthma significantly inhibited airway inflammation, and Cox-2, iNOS, and ADAM33
lung inflammatory gene expression (p<0.05), with 8 and 40 mg/ml treatment groups
expressing the most significant effect. Furthermore, LRP demonstrated an airway
relaxation effect independent of beta receptors, potentially through muscarinic and
histamine receptor antagonism in carbachol-and histamine-pre-contracted GPT rings
(p<0.05). These findings suggest the therapeutic potential of LR mushroom
polysaccharides as complementary alternatives for the management of allergic asthma