Effects of fermented milk peptides supplement on blood pressure and vascular function in spontaneously hypertensive rats

In Vitro and In Vivo Antihypertensive Effect of Milk Fermented with Different Strains of Common Starter Lactic Acid Bacteria

Currently, functional dairy products pave a promising way for the prophylaxis of essential hypertension, and the search for new strains capable of producing such products is a constant challenge for scientists around the world. In this study, the antihypertensive properties of milk fermented with several strains of traditional yogurt starters (Lactobacillus delbrueckii strains Lb100 and Lb200; Lactococcus lactis strains dlA, AM1 and MA1; Streptococcus thermophilus strains 159 and 16t) and one strain of non-conventional probiotic starter (Lacticaseibacillus paracasei ABK) were assessed. The in vitro assessment using angiotensin-converting enzyme inhibition assay was performed for all fermentation products, and the best performed products were tested in vivo using Spontaneously Hypertensive Rat (SHR) animal model. In addition, for the best performed products the fatty acid (FA) composition and FA-related nutritional indices were determined. As a result, the milk fermented with two strains (Lb. delbrueckii LB100 and Lc. lactis AM1) demonstrated significant antihypertensive effect during both in vitro and in vivo experiments. Moreover, the milk fermented with Lb. delbrueckii Lb100 demonstrated significantly better FA-related nutritional indexes and lowered total cholesterol in SHRs upon regular consumption. The obtained results can be used in the future to develop new starter cultures producing effective functional antihypertensive dairy products.

Influence of fermented soy protein consumption on hypertension and gut microbial modulation in spontaneous hypertensive rats

Plant proteins are known to possess important bioactive peptides and have a positive impact on gut microbial modulation. In this study, we studied the ability of a single dose of a fermented soy protein product (P-SPI) to reduce high blood pressure in spontaneous hypertensive rats (SHR) and how it modulates the gut microbiota after six weeks of feeding. SHRs were fed with P-SPI, Captopril or distilled water once, and their blood pressures were monitored from the first to twelfth-hour post-administration. Consumption of P-SPI significantly reduced systolic and diastolic blood pressures up to the sixth hour by 25 ± 4 mmHg and 40 ± 5 mmHg respectively. P-SPI consumption inhibited serum ACE activity, increased superoxide dismutase activity and nitric oxide levels and reduced malondialdehyde levels in serum. Analysis of fecal microbial 16S rRNA of hypertensive rats revealed a significant reduction in microbial richness and diversity in the gut, while P-SPI consumption improved microbial richness and increased diversity. Also, P-SPI feeding significantly reduced the Firmicutes/Bacteroidetes ratio, increased propionate- and H₂S-producing bacteria and reduced Streptococcaceae and Erysipelotrichales levels. Our results show that P-SPI is a potential antihypertensive functional food which could remodel the altered gut microbiota of hypertensive patients.

Purification of novel angiotensin converting enzyme inhibitory peptides from beef myofibrillar proteins and analysis of their effect in spontaneously hypertensive rat model

This study was conducted to purify the angiotensin converting enzyme (ACE) inhibitory peptides from beef myofibrillar proteins by using inexpensive enzymes alkaline-AK and papain. Different molecular weight peptides (<3 and <10 kDa) were obtained using ultrafiltration. The <3 kDa peptides obtained by alkaline-AK (AK3K) digestion showed the highest ACE inhibitory activity (74.29%) as compared to other alkaline-AK peptides, and a strong antihypertensive effect of AK3K was observed in the spontaneously hypertensive rat (SHR) model. The AK3K treatment groups (400 and 800 mg/kg body weight) exhibited a decrease in systolic blood pressure (SBP) by 28 and 35 mmHg, respectively in the SHR model. The study demonstrated that the ACE inhibitory peptide obtained from beef myofibrillar proteins had the sequence Leu-Ile-Val-Gly-Ile-Ile-Arg-Cys-Val, and could be possibly used for lowering the SBP.

Mechanistic Pathways Underlying the Antihypertensive Effect of Fermented Milk with Lactococcus lactis NRRL B-50571 in Spontaneously Hypertensive Rats

It has been reported that fermented milk (FM) with Lactococcus lactis NRRL B-50571 had an antihypertensive effect in spontaneously hypertensive rats (SHR) and prehypertensive subjects. Therefore, the objective of the present study was to evaluate the possible mechanisms involved (angiotensin converting enzyme inhibition (ACEI), enhancement of nitric oxide production, antioxidant activity and opioid effect), in the antihypertensive effect of FM with SHR. First, twenty one SHR were randomized into three groups to either receive in a single-oral dose of purified water (negative control), FM, or naloxone (opioid receptor antagonist) + FM. In a parallel study, twenty seven SHR were randomized into three groups to either receive ad libitum purified water (negative control), Captopril or FM. After six weeks of treatment ACEI activity, enhancement of nitric oxide production, and antioxidant activity were evaluated in plasma. Results indicated that opioid receptors were not involved in the hypotensive effect of FM. However, ACEI activity (94 U/L), the oxidative stress index (malondialdehyde/catalase + glutathione peroxidase) 0.9, and nitric oxide in plasma (4.4 ± 1.3 U/L), were significantly different from the negative control, and not significantly different from the Captopril group. Thus, these results suggested that these mechanisms are involved in the hypotensive effect of FM.

Randomized double-blind controlled clinical trial of the blood pressure-lowering effect of fermented milk with Lactococcus lactis: A pilot study

The blood pressure-lowering effect of fermented milk with Lactococcus lactis NRRL B-50571 was evaluated in a double-blind randomized controlled clinical trial with prehypertensive subjects. Participants were randomized into 2 groups (n = 18 each group): one group treated with fermented milk with Lactococcus lactis NRRL B-50571 and a control group treated with artificially acidified milk. Results revealed that during daily consumption of fermented milk for 5 wk, systolic [(116.55 ± 12.26 mmHg vs. 124.77 ± 11.04 mmHg) and diastolic blood pressure (80.7 ± 9 vs. 84.5 ± 8.5 mmHg)] from the fermented milk group was lower than the control group. Additionally, triglyceride, total cholesterol, and low-density lipoprotein in blood serum were lower in the fermented milk group than in the control group. Results demonstrated that daily consumption of fermented milk with Lactococcus lactis (NRRL B-50571) had a blood pressure-lowering effect on prehypertensive subjects. Regular consumption of this product may be used as a potential functional food.

Effects of natural peptides from food proteins on angiotensin converting enzyme activity and hypertension

Cardiovascular diseases are the leading cause of death. The underlying pathophysiology is largely contributed by an overactivation of the renin-angiotensin-aldosterone-system (RAAS). Herein, angiotensin II (AngII) is a key mediator not only in blood pressure control and vascular tone regulation, but also involved in inflammation, endothelial dysfunction, atherosclerosis, hypertension and congestive heart failure. Since more than three decades suppression of AngII generation by inhibition of the angiotensin-converting enzyme (ACE) or blockade of the AngII-receptor has shown clinical benefit by reducing hypertension, atherosclerosis and other inflammation-associated cardiovascular diseases. Besides pharmaceutical ACE-inhibitors some natural peptides derived from food proteins reduce in vitro ACE activity. Several animal studies and a few human clinical trials have shown antihypertensive effects of such peptides, which might be attractive as food additives to prevent age-related RAAS activation. However, their inhibitory potency on in vitro ACE activity does not always correlate with an antihypertensive impact. While some peptides with high inhibitory activity on ACE-activity in vitro show no antihypertensive effect in vivo, other peptides with only a moderate ACE inhibitory activity in vitro cause such effects. The explanation for this conflicting phenomenon between inhibitory activity and antihypertensive effect remains unclear to date. This review shall critically address the effects of natural peptides derived from different food proteins on the cardiovascular system and the possible underlying mechanisms. A central aspect will be to point to conceptual gaps in the current understanding of the action of these peptides with respect to in vivo blood pressure lowering effects.

Recent Research in Antihypertensive Activity of Food Protein-derived Hydrolyzates and Peptides

Year to year obesity prevalence, reduced physical activities, bad habits/or stressful lifestyle, and other environmental and physiological impacts lead to increase in diseases such as coronary heart disease, stroke, cancer, diabetes, and hypertension worldwide. Hypertension is considered as one of the most common serious chronic diseases; however, discovery of medications with high efficacy and without side effects for treatment of patients remains a challenge for scientists. Recent trends in functional foods have evidenced that food bioactive proteins play a major role in the concepts of illness and curing; therefore, nutritionists, biomedical scientists, and food scientists are working together to develop improved systems for the discovery of peptides with increased potency and therapeutic benefits. This review presents a recent research carried out to date for the purpose of isolation and identification of bioactive hydrolyzates and peptides with angiotensin I converting enzyme inhibitory activity and antihypertensive effect from animal, marine, microbial, and plant food proteins. Effects of food processing and hydrolyzation conditions as well as some other impacts on formation, activity, and stability of these hydrolyzates and peptides are also presented.

Long-term antihypertensive effects of far-infrared ray irradiated from wooden board in spontaneously hypertensive rats

Background

Far-infrared ray (FIR) has been widely used in promoting health and has been shown to exert beneficial effects in vascular function. The non-thermal effect of FIR has been found to play a significant role in the protective effect on some vascular-related diseases, but its protective effects and use against hypertension have not been clearly presented.

Methods

In the present study, by using a wooden board coated with FIR-irradiated materials, we evaluated the long-term antihypertensive effect on spontaneously hypertensive rats (SHRs) in the environment in contact with the FIR-irradiated wooden board. SHRs were placed on the wooden board with or without FIR radiation for 4 weeks.

Results

The systolic blood pressure (BP) of SHRs undergoing different treatments was measured weekly using a tail-cuff method. FIR radiation significantly reduced the systolic BP of the SHRs along with a decreasing plasma level of angiotensin II and an increasing plasma level of bradykinin. In addition, long-term contact of FIR did not significantly affect the BP in normotensive Wistar Kyoto rats (WKYs).

Conclusions

Our results provided the evidence based on which FIR radiation could be considered an effective non-pharmacological choice for preventing hypertension.

Preventive and treatment effects of a hemp seed (Cannabis sativa L.) meal protein hydrolysate against high blood pressure in spontaneously hypertensive rats

PURPOSE

This work determined the ability of hemp seed meal protein hydrolysate (HMH)-containing diets to attenuate elevated blood pressure (hypertension) development in spontaneously hypertensive rats (SHRs). Effects of diets on plasma levels of renin and angiotensin I-converting enzyme (ACE) in the SHRs were also determined.

METHODS

Defatted hemp seed protein meal was hydrolyzed using simulated gastrointestinal tract digestion with pepsin followed by pancreatin, and the resulting HMH used as a source of antihypertensive peptides. The HMH was substituted for casein at 0.5 and 1.0% levels and fed to young growing rats for 8 weeks (preventive phase) or adult rats for 4 weeks (treatment phase).

RESULTS

Feeding of young growing SHRs with HMH resulted in attenuation of the normal increases in systolic blood pressure (SBP) with an average value of ~120 mmHg when compared to the casein-only group of rats (control) with a maximum of 158 mm Hg (p < 0.05). Feeding adult rats (SBP ~145 mmHg) with same diets during a 4-week period led to significant (p < 0.05) reduction in SBP to ~119 mmHg in comparison with 150 mmHg for the control rats. Plasma ACE activity was significantly (p < 0.05) suppressed (0.047-0.059 U/mL) in HMH-fed rats when compared to control rats (0.123 U/mL). Plasma renin level was also decreased for HMH-fed rats (0.040-0.054 μg/mL) when compared to control rats that were fed only with casein (0.151 μg/mL).

CONCLUSIONS

The results suggest that HMH with strong hypotensive effects in SHRs could be used as a therapeutic agent for both the prevention and treatment of hypertension.