Kinetics of Enzyme Inhibition and Antihypertensive Effects of Hemp Seed (Cannabis sativa L.) Protein Hydrolysates

Abstract

The aim of this study was to determine the antihypertensive effects of enzymatic hemp seed protein hydrolysate (HPH) and its peptide fractions. Hemp seed protein isolate was digested by the sequential action of pepsin and pancreatin to mimic gastrointestinal digestion in human beings. The resultant HPH was separated by membrane ultrafiltration into peptide fractions with different sizes (\1 and 1-3 kDa). The HPH led to significantly higher (P \ 0.05) in vitro inhibition of the activities of angiotensin I-converting enzyme (ACE) and renin, the two main enzymes involved in abnormal blood pressure elevation (hypertension). Kinetic studies showed that HPH and peptide fractions inhibited renin and ACE activities in a mixed-type pattern, indicating binding to areas other than the active site. Oral administration of HPH (200 mg/kg body weight) to spontaneously hypertensive rats led to significant reductions (P \ 0.05) in systolic blood pressure (SBP) that reached a maximum of -30 mmHg after 8 h. In contrast, the hypotensive effects of peptide fractions (\1 and 1-3 kDa) had a maximum value of about -15 mmHg after 6-8 h post oral administration. The results suggest a synergistic antihypertensive effect of the peptides present within HPH; this effect was reduced significantly (P \ 0.05) upon separation into peptide fractions.

In vitro antioxidant and α-amylase inhibitory properties of watermelon seed protein hydrolysates

“…The reported 46% degree of tryptic hydrolysis of canola protein (Alashi et al 2014) and 19% degree of alcalase hydrolysis of hemp seed protein (Girgih et al 2011) were also higher than that obtained in this study. The low degree of alcalase hydrolysis may be attributed to the low E:S ratio because other studies with higher DH used a higher E:S ratio (Alashi et al 2014;Girgih et al 2011;Li et al 2011;Malomo et al 2015;Udenigwe et al 2009). …”

“…The 68.9% peptide yield of peptic digestion obtained in this study was slightly higher than the 65.7% previously reported for hemp seed peptic protein hydrolysis (Girgih et al 2011). The higher percentage peptide yield of peptic digestion (68.9%) could be attributed to the moderate specificity of pepsin where several residues are potential targets of its cleavage compared to the highly specific trypsin.…”

“…The degree of tryptic hydrolysis (26.26 ± 0.27%) achieved in the present study is higher than 14.3 ± 0.1% reported for Jelly fish protein hydrolysates by Zhuang et al (2010); and 21.79 ± 0.77% previously reported for whey protein tryptic hydrolysate where tryptic hydrolysis also had the highest DH (Kamau, Lu 2010). However, the DH (19.38 ± 0.86%) obtained for pepsin is lower than the previously reported values for peptic hydrolysis of hemp seed protein (39.1%; Girgih et al 2011) and Australian canola protein (Alashi et al 2014). The reported 46% degree of tryptic hydrolysis of canola protein (Alashi et al 2014) and 19% degree of alcalase hydrolysis of hemp seed protein (Girgih et al 2011) were also higher than that obtained in this study.…”

“…The percentage peptide yield was determined using the method described by Girgih et al (2011). The peptide yield (%) of CSPH was calculated as the ratio of peptide weight of lyophilised hydrolysate to the protein weight of protein isolate as shown: Peptide Yield % = Peptide weight of lyophilised hydrolistae (mg mL ) × 100 (%).…”

Antihypertensive properties of tilapia (Oreochromis spp.) frame and skin enzymatic protein hydrolysates

“…In vitro inhibition of human recombinant renin was conducted using Renin Inhibitor Screening Assay Kit according to the method described by Girgih et al [29]. Peptide fractions were dissolved in Tris-HCl buffer (50 mM, pH 8) containing 100 mM NaCl.…”