Kinetics of angiotensin -1 converting enzyme inhibition and antioxidative properties of Azadirachta indica seed protein hydrolysates
Rotimi O. Arise,
Marvellous A. Acho,
Abeeb A. Yekeen,
Ibrahim A. Omokanye,
Elizabeth O. Sunday-Nwaso,
Olatunbosun S. Akiode,
Sylvia O. Malomo
Affiliations
Rotimi O. Arise
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria; Department of Biological Sciences, College of Science and Engineering, Landmark University, Omu-Aran, Kwara State, Nigeria; Corresponding author.
Marvellous A. Acho
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria; Department of Biotechnology and Food Technology, Faculty of Applied Sciences, Durban University of Technology, Durban, South Africa
Abeeb A. Yekeen
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria; School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
Ibrahim A. Omokanye
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria
Elizabeth O. Sunday-Nwaso
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria
Olatunbosun S. Akiode
Sheda Science and Technology Complex, Km 10 from Gwagwalada, Abuja-Lokoja Expressway, Abuja, Nigeria
Sylvia O. Malomo
Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria
Neem (Azadirachta indica) seed protein hydrolysates were investigated for in vitro antioxidant and angiotensin 1-converting enzyme (ACE)-inhibitory activities. Neem seed proteins were hydrolysed using pepsin, trypsin and Alcalase. The degree of pepsin hydrolysis of neem seed protein was significantly higher (p < 0.05) than those of trypsin and Alcalase hydrolysis. Proteolytic hydrolysis of the isolate resulted in hydrolysates with improved Arg/Lys ratio, with pepsin hydrolysates still being able to maintain an acceptable level of essential amino acids comparable to that of the isolate. At 2.5 mg/mL, pepsin neem seed protein hydrolysate (NSPH) demonstrated the strongest antioxidant activity with 67.15 % and 50.07 % DPPH- and superoxide anion radical-scavenging activities, respectively, while trypsin NSPH had the highest ferric-reducing power. Using N-[3-(2-furyl)acryloyl]-L-phenylalanyl-glycyl-glycine (FAPGG) as substrate, NSPHs strongly inhibited ACE (69.20–80.39 %) in a concentration-dependent manner. Pepsin NSPH had higher ACE-inhibitory activity than trypsin and Alcalase NSPHs. Kinetic studies showed the mechanism of ACE inhibition to be mixed-type with Ki values of 0.62, 0.84, 1.5 for pepsin, trypsin and alcalase NSPH, respectively. These results suggest that NSPH can be used as a potential nutraceutical with antioxidant capacity and inhibitory activity against ACE.