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

doi:10.1016/j.heliyon.2019.e01747

Kinetics of angiotensin -1 converting enzyme inhibition and antioxidative properties of Azadirachta indica seed protein hydrolysates

Heliyon. 2019 May 27;5(5):e01747. doi: 10.1016/j.heliyon.2019.e01747. eCollection 2019 May.

Authors

Rotimi O Arise^{1

2}, Marvellous A Acho^{1

3}, Abeeb A Yekeen^{1

4}, Ibrahim A Omokanye¹, Elizabeth O Sunday-Nwaso¹, Olatunbosun S Akiode⁵, Sylvia O Malomo¹

Affiliations

¹ Department of Biochemistry, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Kwara State, Nigeria.
² Department of Biological Sciences, College of Science and Engineering, Landmark University, Omu-Aran, Kwara State, Nigeria.
³ Department of Biotechnology and Food Technology, Faculty of Applied Sciences, Durban University of Technology, Durban, South Africa.
⁴ School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China.
⁵ Sheda Science and Technology Complex, Km 10 from Gwagwalada, Abuja-Lokoja Expressway, Abuja, Nigeria.

Abstract

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.

Keywords: Biochemistry.