Suppressive activity of enzymatically-educed soy protein hydrolysates on degranulation in IgE-antigen complex-stimulated RBL-2H3 cells

Background: Soy protein isolate (SPI) is increasingly used in foods because it is a high quality non-dairy protein with excellent functional properties. However, soy allergy is one of the world’s major eight food allergies. Objective: To investigate the anti-allergic activity of soy protein hydrolysates (SPHs) produced with alcalase and pepsin proteases. Methods: SPI was enzymatically hydrolysed using the proteases, while evaluating the reaction conditions which include E/S (enzyme to substrate ratio) of 0.5%, 1.0% and 1.5% (250 u/mg and 5 u/g of pepsin and alcalase respectively); and hydrolysis time (0 min, 30 min, 1h, 2h, 4h and 8h). Afterwards, rat basophilic leukaemia (RBL)-2H3 cells activated by the IgE-antigen complex were used to assess mast cell degranulation inhibitory activity of the SPHs by the release of β-hexosaminidase. RBL-2H3 cells were sensitized with monoclonal anti-dinitrophenol (DNP) specific IgE and challenged with the antigen DNP-bovine serum albumin in the presence or absence of SPHs. Results: It was observed that 0.1 mg/mL concentration of the 0.5% E/S SPHs prepared in the first 4h significantly (P < 0.05) inhibited β-hexosaminidase release in an IgE-antigen complex-stimulated RBL-2H3 cells compared to those produced at other time intervals, E/S, and concentrations. Conclusion: This is the first report of its kind that shows the ability of SPHs to suppress degranulation of RBL-2H3 cells. Consequently, SPHs have good prospects to be used as potential sources of low cost hypo or anti-allergic protein