Natural Fused Heterocyclic Flavonoids: Potent Candidates as Anti- Inflammatory and Anti-Allergic Agents in the Treatment of Asthma

Background: In the last two decades, the flavonoids containing fused heterocyclic nucleus in their chemical structure have emerged to display a variety of pharmacological effects including antiallergic and anti-inflammatory the most recent to the list. These polyphenolic compounds exert their pharmacological effect by various mechanisms including inhibition of human neutrophil elastase, cytokines (Interleukins- IL-3 and IL-4) and mast cells. Methods: We adopted a structured search of notorious journal publication websites and electronic databases such as Science Direct, Bentham, Scopus, PubMed, Nature, Springer etc. for the collection of peer-reviewed research and review articles for the present review. The quality papers (109) were retrieved, studied, categorized into different sections, analyzed and used for article writing. Results: The backbone of this review article is based on four review articles of natural phenolics. Seventeen papers out of total one hundred and nine were about Quercetin the main molecule of interest, five papers outlined the potential benefits of Pycnogenol, Rutin was discussed in detail by considering eight papers in mind, Kaempferol which can be considered as a candidate of interest was referred from six articles. Conclusion: This review identified the Quercetin, Pycnogenol, Rutin and Kampferol as few bioflavonols out of hundreds of other compounds still under clinical trials that have been studied most. Marketed formulations of Pycnogenol are also available as nutraceuticals. These flavonoids have been also reported to the other pharmacological effects like anti-cancer, anti-oxidants, anti-hypertensive, antiviral, anti-ulcerogenic, anti-platelet, anti-hypotensive and anti-hepatotoxic. With all these versatile properties heterocyclic containing flavonoids may be a powerful candidate for the discovery of their utilization in other ailments like asthma.