Professor/ Director RCFTR University of Manitoba Winnipeg, Manitoba, Canada
Abstract: High levels of oxidative stress occur during aging and contribute to the development of various chronic degenerative diseases such as cancer, hypertension, kidney malfunction, dementia, and arteriosclerosis. Therefore, the use of exogenous sources of antioxidants could assist in fortifying the human body against high levels of destructive reactive oxygen species. Thus, the aim of this work was to determine the efficacy of isolated hemp seed protein and hydrolyzed hemp seed protein in reducing oxidative stress in adult spontaneously hypertensive rats (SHR). Hemp seed protein isolate (HPI) was produced from defatted hemp seed meal through alkaline extraction followed by acid-induced protein precipitation at pH 5. Hemp seed protein hydrolysate (HPH) was produced after sequential digestion of the defatted meal with pepsin and pancreatin. In vitro antioxidative activity was tested using radical scavenging (DPPH, superoxide, and hydroxyl) and metal chelation assays. In vivo studies used 20-week-old SHR, which were divided into 4 groups of 4 rats each. A control set of rats consisted of normotensive Wistar Kyoto rats. Rats were fed diets containing one of the following as protein source for 4 weeks: 20% casein, 19.5% casein + 0.5% HPH, 19% casein + 1% HPH, and 19% casein + 1% HPI. Upon termination, the level of antioxidative enzymes and total peroxides were determined in the blood. Results showed that the HPH had strong in vitro radical scavenging and metal chelation activities. The SHR plasma levels of superoxide dismutase and catalase were significantly reduced during aging but inclusion of HPI or HPH in the diet led to significant increases. Plasma total peroxides also increased significantly during aging but was ameliorated by HPI and HPH diets. However, inclusion of HPI or HPH in the diets did not rescue the significantly low levels of total antioxidant capacity when compared to young rats.
