Anti-Allergic Rhinitis Effects of Medicinal Plants and Their Bioactive Metabolites via Suppression of the Immune System: A Mechanistic Review

Abstract

Allergic rhinitis (AR) is a common inflammatory condition of the nasal mucosa and it is an immunoglobulin E–mediated disease. The incidence and prevalence of AR globally have been escalating over recent years. Antihistamines, intranasal corticosteroids, decongestants, intranasal anticholinergics, intranasal cromolyn, leukotriene receptor antagonists and immunotherapy have been used in the treatment of AR. However, there is a need to search for more effective and safer remedies as many of the current treatments have reported side effects. Medicinal plants have been used traditionally to relief symptoms of AR but their efficacy and safety have not been scientifically proven. In this review, up-to-date reports of studies on the anti-allergic rhinitis of several medicinal plants and their bioactive metabolites through suppression of the immune system are compiled and critically analyzed. The plant samples were reported to suppress the productions of immunoglobulin E, cytokines and eosinophils and inhibit histamine release. The suppression of cytokines production was found to be the main mechanistic effect of the plants to give symptomatic relief. The prospect of these medicinal plants as sources of lead molecules for development of therapeutic agents to treat AR is highlighted. Several bioactive metabolites of the plants including shikonin, okicamelliaside, warifteine, methylwarifteine, luteolin-7-O-rutinoside, tussilagone, petasin, and mangiferin have been identified as potential candidates for development into anti-allergic rhinitis agents. The data collection was mainly from English language articles published in journals, or studies from EBSCOHOST, Medline and Ovid, Scopus, Springer, and Google Scholar databases from the year 1985–2020. The terms or keywords used to find relevant studies were allergic rhinitis OR pollinosis OR hay fever, AND medicinal plant OR single plant OR single herb OR phytotherapy. This comprehensive review serves as a useful resource for medicinal plants with anti-allergic rhinitis potential, understanding the underlying mechanisms of action and for future exploration to find natural product candidates in the development of novel anti-allergic rhinitis agents.

Tussilagone protects acute lung injury from PM2.5 via alleviating Hif‐1α/NF‐κB‐mediated inflammatory response

“…Some studies have suggested that TSL, as an immune repressor, inhibits NF‐κB signaling and MAPK pathway, thereby reducing the inflammatory activation and M1 polarization of RAW264.7 50 . In addition, TSL has a good therapeutic effect on many autoimmune diseases 49 . In our study, different concentrations of TSL decelerated PM2.5‐induced cell damage and inflammation.…”

“…50 In addition, TSL has a good therapeutic effect on many autoimmune diseases. 49 In our study, different concentrations of TSL decelerated PM2.5-induced cell damage and inflammation. Particularly, a high dosage of TSL completely improved and rescued the functions of PM2.5 exposure on lung epithelial cells, not only reducing cell apoptosis and inhibiting inflammatory response, but also significantly limiting the activation of NF-κB signaling (Figures 3 and 4).…”

“…Specific inhibitors of NF‐κB signaling have certain cytotoxicity, and systemic inflammatory response is often unstable when administered in vivo. In fact, many natural compounds have been proved to present certain functions of regulating inflammatory response and promoting tissue damage repair 48,49 . TSL is a ketone compound isolated from Tussilago farfara.…”

“…In fact, many natural compounds have been proved to present certain functions of regulating inflammatory response and promoting tissue damage repair. 48,49 TSL is a ketone compound isolated from Tussilago farfara. According to the view of traditional oriental medicine, TSL administration alleviates immune response in acute and chronic inflammatory injury.…”

Astragalus Polysaccharide Relieves Inflammatory Responses in Guinea Pigs with Allergic Rhinitis via Ameliorating NF-kB-Mediated Treg/Th17 Imbalance

“…6 On a separate note, a former review by Rahim et al highlighted that extracts derived from certain medicinal plants possess an anti-AR effect. 31 APS derived from Astragalus membranaceus has various pharmacological properties and is regarded as a plant component with promising potential to improve or treat multiple diseases. 32 Furthermore, APS is used for treating airway inflammation dominated by neutrophil and eosinophils, and could attenuate allergic symptoms of AR.…”