Clinacanthus nutans Aqueous Extract But Not Ethanolic Extract Inhibits the Release of Preformed Mediators in In Vitro Model of IgE-Mediated Mast Cell Degranulation

Abstract

C. nutans (Burm. f.) Lindau is a shrub that is commonly found in South East Asia, particularly in Malaysia, Thailand and Indonesia. This plant has diverse and potential medicinal uses in traditional herbal medicine for treating many diseases which include skin rashes. Skin rash is one of the symptoms that primarily occur in people with allergies. Till date, there has been no scientific evidence to support this traditional use of C. nutans as well as its potential of possessing anti-allergic properties. IgE and mast cells play an important role in the pathogenesis of allergy. Upon cross-linking of allergen to IgE antibodies bound to FcεRI on mast cells, pro-inflammatory mediators will be released as a result of degranulation. The release of pro-inflammatory mediators by mast cells activated by allergen in the skin causes large, itchy, red swellings of the skin. This study aimed to identify the most active C. nutans extract in inhibiting in vitro IgE-mast cell degranulation. Rat basophilic leukaemic cells (RBL-2H3) were pre-sensitised with IgE, pre-treated with C. nutans ethanolic (100%, 70% and 50%) or aqueous extracts and challenged with dinitrophenyl-bovine serum albumin (DNP-BSA) accordingly to analyse the release of β-hexosaminidase, histamine, interleukin (IL)-4 and tumour necrosis factor (TNF)-α. It was found that C. nutans aqueous extract was the most active extract compared to the ethanolic extracts as it was able to inhibit the release of β-hexosaminidase and histamine at concentrations of 5 mg/ml and above.