Preparation of bioactive peptides with high angiotensin converting enzyme inhibitory activity from winged bean [Psophocarpus tetragonolobus (L.) DC.] seed (original) (raw)

Winged bean [Psophocarpus tetragonolobus (L.) DC.] seed is a potential underexploited source of vegetable protein due to its high protein content. In the present work, undefatted and defatted winged bean seed hydrolysates, designated as UWBSH and DWBSH, respectively were produced separately by four proteolytic enzymes namely Flavourzyme, Alcalase, Bromelain, and Papain using pH-stat method in a batch reactor. Enzymatic hydrolysis was carried out over a period of 0.5 to 5 h. UWBSH and DWBSH produced were tested for their ACE inhibitory activity in relation to the hydrolysis time and degree of hydrolysis (DH). Maximum ACE inhibitory activity, both for UWBSH and DWBSH, were observed during 3 to 5 h of hydrolysis. Both, UWBSH (DH 91.84 %), and DWSBH (DH 18.72 %), produced by Papain at 5 h hydrolysis, exhibited exceptionally high ACE inhibitory activity with IC 50 value 0.064 and 0.249 mgmL −1 , respectively. Besides, papain-produced UWBSH and DWBSH were further frac-tionated into three fractions based on molecular weight (UWBSH-I, <10 kDa; UWBSH-II, <5 kDa; UWBSH-III, <2 kDa) and (DWBSH-I, <10 kDa; DWBSH-II, <5 kDa; DWBSH-III, <2 kDa). UWBSH-III revealed the highest ACE inhibitory activity (IC 50 0.003 mgmL −1) compared with DWBSH-III (IC 50 0.130 mgmL −1). The results of the present investigation revealed that winged bean seed hydro-lysates can be explored as a potential source of ACE inhibitory peptides suggesting their uses for physiological benefits as well as for other functional food applications. Keywords Undefatted and defatted winged bean seed. Proximate analysis. ACE inhibitory activity. IC 50 value. Degree of hydrolysis. pH-stat titration