Antioxidant, Angiotensin-Converting Enzyme Inhibitory Properties and Blood-Pressure-Lowering Effect of Rice Bran Protein Hydrolysates.

Inajara Beatriz Brose Piotrowicz,Myriam Salas-Mellado,Marta Garcés-Rimón,Amaya Aleixandre,Silvia Moreno-Fernández,Marta Miguel-Castro

doi:10.3390/foods9060812

Abstract

This research aimed to investigate the biological properties of different hydrolysates derived from industrial and laboratory defatted rice bran proteins. Industrial and laboratory defatted rice bran protein concentrates were hydrolyzed with alcalase or flavorzyme. The degree of hydrolysis (DH), oxygen radical absorbance capacity (ORAC), reducing power, total phenolic compounds (TPC), and angiotensin-converting enzyme (ACE) inhibitory activity, were determined in the hydrolysates and the molecular fractions lower than 3 kDa. Systolic blood pressure (SBP) was measured using the tail-cuff method before and after oral administration of 80 mg/kg of different rice bran protein hydrolysate (RBPH) fractions lower than 3 kDa in male spontaneously hypertensive rats (SHR) and normotensive Wistar–Kyoto (WKY) rats. The highest values of in vitro antioxidant activity and TPC were observed in RBPH with alcalase defatted by industry (RBPH2A), and, in all cases, these bioactivities were higher in the molecular fractions lower than 3 kDa. Once again, fractions lower than 3 kDa obtained with alcalase showed a potent ACE inhibitory activity (RBPH1A<3 and RBPH2A<3). The administration of RBPH1A<3 caused a significant decrease in the SBP in SHR, where the maximum decrease was reached at 8 h after administration. SBP in WKY rats was not modified after the administration of RBPH1A<3. These results suggest that the rice bran protein hydrolysates obtained from industry after treatment with alcalase could be an interesting source of bioactive peptides, with potential action on hypertension and other related pathologies.

Highlights

Cardiovascular diseases (CVDs) are considered the most important health problem in industrialized countries
The main aims of this work were: (1) to obtain hydrolysates from industrial and laboratory defatted rice bran protein concentrates using different food-grade microbial enzymes, (2) to investigate the in vitro antioxidant and angiotensin-converting enzyme (ACE) inhibitory properties of these hydrolysates and (3) to evaluate the in vivo activity of the selected rice bran protein hydrolysates in spontaneously hypertensive rats (SHR)
rice bran protein hydrolysate (RBPH)-1A: concentrate DRBPC-1 hydrolyzed with alcalase; RBPH-2A: concentrate DRBPC-2 hydrolyzed with alcalase; RBPH-1F: concentrate DRBPC-1 alcalase; RBPH-2A: concentrate DRBPC-2 hydrolyzed with alcalase; RBPH-1F: concentrate DRBPC-1 hydrolyzed with flavorzyme; RBPH-2F: concentrate DRBPC-2 hydrolyzed with flavorzyme

Summary

Introduction

Cardiovascular diseases (CVDs) are considered the most important health problem in industrialized countries. These pathologies represent the main cause of death worldwide, with hypertension being one of the main risk factors for developing CVD [1]. Hypertension is normally treated with drugs, in particular with angiotensin-converting enzyme (ACE) inhibitors. ACE plays an important physiological role in the regulation of blood pressure. Angiotensin-I is transformed to angiotensin-II by the action of ACE, resulting in arterial constriction and blood pressure elevation [2].

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