Effect of γ-aminobutyric acid and nattokinase-enriched fermented beans on the blood pressure of spontaneously hypertensive and normotensive Wistar-Kyoto rats

Contributions of Gamma-Aminobutyric Acid (GABA) Produced by Lactic Acid Bacteria on Food Quality and Human Health: Current Applications and Future Prospects

The need to increase food safety and improve human health has led to a worldwide increase in interest in gamma-aminobutyric acid (GABA), produced by lactic acid bacteria (LABs). GABA, produced from glutamic acid in a reaction catalyzed by glutamate decarboxylase (GAD), is a four-carbon, non-protein amino acid that is increasingly used in the food industry to improve the safety/quality of foods. In addition to the possible positive effects of GABA, called a postbiotic, on neuroprotection, improving sleep quality, alleviating depression and relieving pain, the various health benefits of GABA-enriched foods such as antidiabetic, antihypertension, and anti-inflammatory effects are also being investigated. For all these reasons, it is not surprising that efforts to identify LAB strains with a high GABA productivity and to increase GABA production from LABs through genetic engineering to increase GABA yield are accelerating. However, GABA's contributions to food safety/quality and human health have not yet been fully discussed in the literature. Therefore, this current review highlights the synthesis and food applications of GABA produced from LABs, discusses its health benefits such as, for example, alleviating drug withdrawal syndromes and regulating obesity and overeating. Still, other potential food and drug interactions (among others) remain unanswered questions to be elucidated in the future. Hence, this review paves the way toward further studies.

Versatile Effects of GABA Oolong Tea on Improvements in Diastolic Blood Pressure, Alpha Brain Waves, and Quality of Life

Emerging evidence has demonstrated that using a new manufacturing technology to produce γ-aminobutyric acid (GABA)-fortified oolong (GO) tea could relieve human stress and exert versatile physiological benefits. The purpose of this human study was to investigate the therapeutic effects of daily GO tea consumption on improvements in blood pressure, relaxation-related brain waves, and quality of life (QOL) over a period of 28 consecutive days. Total polyphenols, major catechins, and free amino acids were analyzed via an HPLC assay. Changes in heart rate, blood pressure, α brain waves (index of relaxation), and the eight-item QOL score were investigated on days 0, 7, 14, 21, and 28. The chemical analysis results showed that GO tea contained the most abundant amino acids and GABA, contributing to the relaxation activity. Among all study participants, the daily consumption of GO tea could reduce systolic blood pressure on day 21 and diastolic blood pressure on day 28 (p < 0.05 for both). For participants with pre-hypertension, GO tea could effectively reduce heart rate and systolic and diastolic blood pressure on day 28 (p < 0.05). At the end of the study, incremental changes in alpha brain waves and QOL scores were also demonstrated (p < 0.05 for both). This study suggests that GO tea might potentially serve as a natural source for alternative therapy to improve blood pressure, stress relief, and QOL.

Research progress on the fibrinolytic enzymes produced from traditional fermented foods

Cardiovascular diseases (CVDs) are a global health problem and leading cause of death worldwide. Thrombus formation, one of the CVDs, is essentially the formation of fibrin clots. The existing thrombolytic agents have the disadvantages of high price, short half-life, and high bleeding risk; hence, there is an urgent need to find the alternative thrombolytic agents. In recent years, traditional fermented foods have been widely investigated for their outstanding effects in the prevention and treatment of thrombus formation. In this review, we have focused on fibrinolytic enzymes produced by microorganisms during the fermentation of traditional fermented foods and their potential use for treating CVDs. First, we discussed about the sources of fibrinolytic enzymes and microbial strains that produce those enzymes followed by the optimization of fermentation process, purification, and physicochemical properties of fibrinolytic enzymes. Finally, we have summarized the thrombolytic effects of fibrinolytic enzymes in humans and mice. Fibrinolytic enzymes produced by microorganisms during the fermentation of traditional fermented foods not only lyse thrombi but also acts as anti-atherosclerotic, anti-hyperlipidemia, and neuroprotection agents. Therefore, fibrinolytic enzymes from traditional fermented foods have great potential for the prevention and treatment of CVDs.

Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

As a fibrinolytic enzyme from fermented soybean, nattokinase has been shown to be potentially beneficial for cardiovascular health, but current clinical evidences regarding the nattokinase supplementation on cardiovascular risk factors are various. This study aims to evaluate the cardiovascular efficacy of nattokinase.

Methods

Four electronic databases were systematically searched to collect eligible randomized controlled trials. Data were extracted and summarized in a pre-designed form by two independent reviewers. Review Manager 5.4 software (Cochrane Library Software, Oxford, U.K.) was used for meta-analysis and bias risk assessment.

Results

Six studies were eligible for quantitative analysis with 546 participants. The overall methodological quality of included studies was high. Relatively low total dosage of nattokinase had a negative effect on blood total cholesterol (MD [mean difference] = 5.27, 95% CI [confidence intervals]: 3.74 to 6.81, p < 0.00001), high-density lipoprotein cholesterol (MD = -2.76, 95% CI: -3.88 to -1.64, p < 0.00001), and low-density lipoprotein cholesterol (MD = 6.49, 95% CI: 0.83 to 12.15, p = 0.02). Nattokinase supplementation significantly reduced systolic blood pressure (MD = -3.45, 95% CI: -4.37 to -2.18, p < 0.00001) and diastolic blood pressure (MD = -2.32, 95% CI: -2.72 to -1.92, p < 0.00001), and led a slight increase in blood glucose (MD = 0.40, 95% CI: 0.20 to 0.60, p < 0.0001) as compared to placebo. Nattokinase group with relatively high total dosage also had a higher total cholesterol (MD = 3.18, 95% CI: 2.29 to 4.06, p < 0.00001) than control interventions, but no significant differences were found in levels of high-density lipoprotein cholesterol and low-density lipoprotein cholesterol. No significant correlation was found between nattokinase supplementation and triglyceride (p = 0.71). No notable adverse events were reported in all studies due to intake of nattokinase.

Conclusions

This study further supports that nattokinase can be used as an effective adjunctive therapy for hypertension, but relatively low-dose supplementation of nattokinase may have no significant lipid-lowering effect. More work will need to be done to determine whether the positive efficacy of nattokinase on cardiovascular risk factors is dose-dependent.

Systematic Review Registration

This work has been registered on PROSPERO (CRD42022315020).

The Potential of an Inexpensive Plant-Based Medium for Halal and Vegetarian Starter Culture Preparation

The restrictions for halal and vegetarian fermented products apply not only to the food ingredients, but also to the inoculum media. The utilization of a medium for lactic acid bacteria (LAB) leads to some issues from animal-derived proteins sources that may be doubtful for halal and/or vegetarian use. This study aimed to develop a plant-based medium for culturing and maintaining LAB. The result demonstrated that 10 g/L soybean powder in sweet potato extract was suitable for cultivating Lactiplantibacillus plantarum TISTR 2075 with no significant difference (p < 0.05) from MRS (de Man, Rogosa and Sharpe) in the cell number (9.12 log CFU/mL) and specific growth rate (0.04). The feasibility of a plant-based medium to grow and maintain the LAB strains from different origins was evaluated. Compared to MRS, Lpb. plantarum TISTR 2075, Lpb. plantarum MW3, and Lacticaseibacillus casei TISTR 1463 could grow almost as well in a plant-based medium. This medium was also suitable for maintaining the viability of LAB during storage, especially when subjected to slant agar stock culture. It is practical and costs at least 10 times less than MRS. Thus, this study created a low-cost plant-based medium that could be used in laboratories, especially for applications in halal and vegetarian food products.

Production, purification, and functional properties of microbial fibrinolytic enzymes produced by microorganism obtained from soy-based fermented foods: developments and challenges

According to the World Health Organization, cardiovascular disease (CVD) has become a major cause of chronic illness around the globe. It has been reported that soy-based fermented food (SFF) is very effective in preventing thrombus (one of the most important contributing factors to CVD), which are mainly attributed to the bioactive substances, especially the fibrinolytic enzymes (FE) generated by microorganisms during the fermentation process of soybean food. This paper therefore mainly reviewed the microbial fibrinolytic enzymes (MFE) from SFF. We first discuss the use of microbial fermentation to produce FE, with an emphasis on the strains involved. The production, purification, physicochemical properties, structure-functional attributes, functional properties and possible application of MFE from SFF are then discussed. Finally, current limitations and future perspectives for the production, purification, and the practical application of MFE are discussed. MFE from SFF pose multiple health benefits, including thrombolysis, antihypertension, anti-inflammatory, anti-hyperlipidemia, anticancer, neuroprotective, antiviral and other activities. Therefore, they exhibit great potential for functional foods and nutraceutical applications, especially foods with CVDs prevention potential.

Fermented soybean foods: A review of their functional components, mechanism of action and factors influencing their health benefits

After thousands of years of evolution and development, traditional fermented soybean foods, with their unique charm, have gained a stable place in the global market. With the explosive development of modern biological technologies, some traditional fermented soybean foods that possess health-promoting benefits are gradually appearing. Physiologically active substances in fermented soybean foods have received extensive attention in recent decades. This review addresses the potential health benefits of several representative fermented soybean foods, as well as the action mechanism and influencing factors of their functional components. Phenolic compounds, low-molecular-weight peptides, melanoidins, furanones and 3-hydroxyanthranilic acid are the antioxidative components predominantly found in fermented soybean foods. Angiotensin I-converting enzyme inhibitory peptides and γ-aminobutyric acid isolated from fermented soy foods provide potential selectivity for hypertension therapy. The potential anti-inflammatory bioactive components in fermented soybean foods include γ-linolenic acid, butyric acid, soy sauce polysaccharides, 2S albumin and isoflavone glycones. Deoxynojirimycin, genistein, and betaine possess high activity against α-glucosidase. Additionally, fermented soybean foods contain neuroprotective constituents, including indole alkaloids, nattokinase, arbutin, and isoflavone vitamin B12. The anticancer activities of fermented soybean foods are associated with surfactin, isolavone, furanones, trypsin inhibitors, and 3-hydroxyanthranilic acid. Nattokinase is highly correlated with antioxidant activity. And a high level of menaquinones-7 is linked to protection against neurodegenerative diseases. Sufficiently recognizing and exploiting the health benefits and functional components of traditional fermented soybean foods could provide a new strategy in the development of the food fermentation industry.

Optimization of fermentation for γ-aminobutyric acid (GABA) production by yeast Kluyveromyces marxianus C21 in okara (soybean residue)

γ-Aminobutyric acid (GABA) is a non-protein amino acid with a variety of physiological functions. Recently, yeast Kluyveromyces marxianus strains involved in the catabolism and anabolism of GABA can be used as a microbial platform for GABA production. Okara, rich in nutrients, can be used as a low-cost fermentation substrate for the production of functional materials. This study first proved the advantages of the okara medium to produce GABA by K. marxianus C21 when L-glutamate (L-Glu) or monosodium glutamate (MSG) is the substrate. The highest production of GABA was obtained with 4.31 g/L at optimization condition of culture temperature 35 °C, fermentation time 60 h, and initial pH 4.0. Furthermore, adding peptone significantly increased the GABA production while glucose and vitamin B6 had no positive impact on GABA production. This research provided a powerful new strategy of GABA production by K. marxianus C21 fermentation and is expected to be widely utilized in the functional foods industry to increase GABA content for consumers as a daily supplement as suggested.

Metabolomic Analysis Reveals Changes of Bioactive Compounds in Mung Beans (Vigna radiata) during γ-Aminobutyric Acid Enrichment Treatment

Soaking together with Heat and Relative Humidity (HRH) treatment has been applied successfully to enrich γ-aminobutyric acid (GABA) in mung beans. However, whether and how the above GABA enrichment processing influences the other bioactive molecules is elusive. In the present study, mung beans were soaked and then treated by HRH for 5 or 7 h. By using metabolomics techniques, the changes of 496 metabolites were determined. The relative content of flavonoids and phenolic acids increased during soaking but slightly decreased during HRH. Intriguingly, soaking and HRH had the opposite effects on the glycosylation of polyphenols. The relative content of glycosylated or un-glycosylated polyphenols increased during soaking or HRH, respectively. The relative content of α-ketoglutaric acid increased more than 20 times after 5 h HRH treatment. Bioactive molecules could be enriched during GABA enrichment processing. Depending on the desired bioactive compounds, soaking and different duration of HRH treatment could be selected.

Clinical and Preclinical Studies of Fermented Foods and Their Effects on Alzheimer’s Disease

The focus on managing Alzheimer’s disease (AD) is shifting towards prevention through lifestyle modification instead of treatments since the currently available treatment options are only capable of providing symptomatic relief marginally and result in various side effects. Numerous studies have reported that the intake of fermented foods resulted in the successful management of AD. Food fermentation is a biochemical process where the microorganisms metabolize the constituents of raw food materials, giving vastly different organoleptic properties and additional nutritional value, and improved biosafety effects in the final products. The consumption of fermented foods is associated with a wide array of nutraceutical benefits, including anti-oxidative, anti-inflammatory, neuroprotective, anti-apoptotic, anti-cancer, anti-fungal, anti-bacterial, immunomodulatory, and hypocholesterolemic properties. Due to their promising health benefits, fermented food products have a great prospect for commercialization in the food industry. This paper reviews the memory and cognitive enhancement and neuroprotective potential of fermented food products on AD, the recently commercialized fermented food products in the health and food industries, and their limitations. The literature reviewed here demonstrates a growing demand for fermented food products as alternative therapeutic options for the prevention and management of AD.

Antihypertensive effect and underlying mechanism of tripeptide NCW on spontaneously hypertensive rats using metabolomics analysis

Tripeptide NCW identified in our previous study displayed a strong ACE inhibitory activity, but whether it has any antihypertensive effect in vivo remains unknown. Thus, in this study, we aimed to investigate the protective effects of tripeptide NCW in spontaneously hypertensive rats (SHRs) and to further figure out the serum metabolic profiling variations due to its oral administration via UPLC-Q-TOF-MS/MS-based metabolomics analysis to clarify the underlying hypotensive mechanism. After three weeks of oral administration, the tripeptide NCW-treated group (NCW/SHR group, 80 mg per kg BW per d) showed significantly reduced systolic and diastolic blood pressure by 48.08 ± 3.84 mmHg and 48.92 ± 5.77 mmHg, respectively. Additionally, a total of 25 blood pressure-related metabolites were identified as being significantly changed in SHRs given tripeptide NCW after three weeks. These 25 metabolites might be biomarkers that indicated that the tripeptide NCW exhibits antihypertensive activity via regulating bile acid metabolism, lipid metabolism, amino acid metabolism, purinergic signaling, pantothenate and CoA biosynthesis, and the citrate cycle. Collectively, tripeptide NCW has a protective effect on SHRs associated with serum metabolite abnormalities.

Selection of Bacteriocinogenic Bacillus spp. from Traditional Fermented Korean Food Products with Additional Beneficial Properties

Two Bacillus spp. isolated from kimchi, Bacillus tequilensis ST816CD and Bacillus subtilis ST830CD, were characterized for their antimicrobial properties and safety. The proteinaceous nature of their inhibitory metabolites was confirmed after exposure to proteolytic enzymes, resulting in partial loss of the antimicrobial effect. This indicated that different non-proteinaceous antimicrobial substances may also be produced by these strains. This hypothesis was later confirmed when genes associated with the production of surfactants were detected in their DNA. The expressed antimicrobial metabolites were not affected by treatment at different temperatures and pH levels, including exposure to selected chemicals. Their strong adherence to susceptible pathogens was not significantly affected by different temperatures, chemicals, or pH values. Both Bacillus strains showed inhibitory activity against clinical and food-associated pathogens, including Listeria monocytogenes ATCC 15313, and some Staphylococcus species. Several genes associated with the production of antimicrobial metabolites were detected, but key virulence and beneficial genes were not present in these strains. Even though only B. tequilensis ST816CD displayed γ-hemolysin production, both selected strains were found to produce gelatinase and biogenic amines, which are considered as either potential virulence- or health-related factors. Moreover, the strains were susceptible to a variety of antibiotics except for the penicillin G [1 IU/disc] resistance of B. tequilensis ST816CD. Both strains showed proteolytic activity. Additionally, both strains showed low hydrophobicity based on bacterial adherence measured by hydrocarbons (n-hexadecane).

Microbial Production and Enzymatic Biosynthesis of γ-Aminobutyric Acid (GABA) Using Lactobacillus plantarum FNCC 260 Isolated from Indonesian Fermented Foods

In the present study, we isolated and screened thirty strains of GABA (γ-aminobutyric acid)-producing lactic acid bacteria (LAB) from traditional Indonesian fermented foods. Two strains were able to convert monosodium glutamate (MSG) to GABA after 24 h of cultivation at 37 °C based on thin layer chromatography (TLC) screening. Proteomic identification and 16S rDNA sequencing using MALDI-TOF MS identified the strain as Lactobacillus plantarum designated as L. plantarum FNCC 260 and FNCC 343. The highest yield of GABA production obtained from the fermentation of L. plantarum FNCC 260 was 809.2 mg/L of culture medium after 60 h of cultivation. The supplementation of 0.6 mM pyridoxal 5’-phosphate (PLP) and 0.1 mM pyridoxine led to the increase in GABA production to 945.3 mg/L and 969.5 mg/L, respectively. The highest GABA production of 1226.5 mg/L of the culture medium was obtained with 100 mM initial concentration of MSG added in the cultivation medium. The open reading frame (ORF) of 1410 bp of the gadB gene from L. plantarum FNCC 260 encodes 469 amino acids with a calculated molecular mass of 53.57 kDa. The production of GABA via enzymatic conversion of monosodium glutamate (MSG) using purified recombinant glutamate decarboxylase (GAD) from L. plantarum FNCC 260 expressed in Escherichia coli was found to be more efficient (5-fold higher within 6 h) than the production obtained from fermentation. L. plantarum FNCC 260 could be of interest for the synthesis of GABA.

Increasing γ-Aminobutyric Acid Content in Vegetable Soybeans via High-Pressure Processing and Efficacy of Their Antidepressant-Like Activity in Mice

This study applied high-pressure processing (HPP) technology to enrich the gamma aminobutyric acid (GABA) content in vegetable soybeans and evaluated its antidepressant efficacy on mice, with depression induced by the unpredictable chronic mild stress (UCMS) model. The optimal conditions for HPP, storage time, and storage temperature, as well as antidepressant-like effects of vegetable soybeans, were evaluated and discussed. HPP could effectively and significantly increase GABA content in soybean, with optimum conditions at 200 MPa. The GABA content in the whole vegetable soybean was 436.05 mg/100 g. In mice animal tests, the tail suspension test (TST) showed that the immobility time of the GABA group was significantly shorter than that of the control group. The total travel distance in the open field test (OFT) showed that depressed mice fed with the GABA feed exhibited exploratory behavior. The GABA group showed a significantly higher degree of sucrose preference than the control group. Both results indicate that the GABA feed could effectively alleviate depressive symptomatology. Regarding biochemical parameters, the fecal and serum corticosterone (CORT) levels in the control group increased to 104.86 pg/mg after the onset of depression. In contrast, the fecal CORT level in the GABA group was significantly reduced to 23.98 pg/mg and was comparable to that in the control group (33.38 pg/mg). Reduced serum CORT level in the GABA group suggests an improvement in depressive symptomatology. The serotonin concentration was maintained in the GABA group after the induction of depression, suggesting its preventive activity. The HPP GABA-enriched soybeans exerted modulatory effects on the behaviors of depressed mice and displayed a potential for commercialization.

Molecular analysis of a fibrin-degrading enzyme from Bacillus subtilis K2 isolated from the Indonesian soybean-based fermented food moromi

The screening of proteolytic and fibrinolytic bacteria from moromi (an Indonesian soybean-based fermented food) yielded a number of isolates. Based on morphological and biochemical analyses and sequencing of the 16S rRNA gene, the isolate that exhibited the highest proteolytic and fibrinolytic activity was identified as Bacillus subtilis K2. The study was performed to analyze molecular characteristic of a fibrin-degrading enzyme from B. subtilis K2. BLASTn analysis of the nucleotide sequence encoding this fibrinolytic protein demonstrated 73.6% homology with the gene encoding the fibrin-degrading enzyme nattokinase of the B. subtilis subsp. natto, which was isolated from fermented soybean in Japan. An analysis of the putative amino-acid sequence of this protein indicated that it is a serine protease enzyme with aspartate, histidine, and serine in the catalytic triad. This enzyme was determined to be a 26-kDa molecule, as confirmed with a zymogram assay. Further bioinformatic analysis using Protparam demonstrated that the enzyme has a pI of 6.02, low instability index, high aliphatic index, and low GRAVY value. Molecular docking analysis using HADDOCK indicated that there are favorable interactions between subtilisin K2 and the fibrin substrate, as demonstrated by a high binding affinity (ΔG: - 19.4 kcal/mol) and low Kd value (6.3E-15 M). Overall, the study concluded that subtilisin K2 belong to serine protease enzyme has strong interactions with its fibrin substrate and fibrin can be rapidly degraded by this enzyme, suggesting its application as a treatment for thrombus diseases.

γ-Aminobutyric acid found in fermented foods and beverages: current trends

γ-aminobutyric acid (GABA) is synthesised by glutamic acid decarboxylase which catalyses the decarboxylation of L-glutamic acid. L-glutamic acid is formed by α-ketoglutarate in the TCA cycle by glutamic acid dehydrogenase (GDH). GABA is found in the human brain, plants, animals and microorganisms. GABA functions as an antidepressant, antihypertensive, antidiabetic and immune system enhancer and has a good effect on neural disease. As GABA have pharmaceutical properties, conditions for GABA production need to be established. Microbiological GABA production is more safe and eco-friendly rather than chemical methods. Moreover, it is easier to control conditions of production using microorganisms compared to production in plants and animals. GABA production in fermented foods and beverages has the potential to be optimised to increase the functional effect of fermented foods and beverages.

Influence of germination on physicochemical properties of flours from brown rice, oat, sorghum, and millet

The changes in physiochemical properties of flours obtained from the four selected grains after germination were investigated. After germination, the sprout length of sorghum and millet was substantially larger than that of brown rice and oat. Germination led to a decrease in the apparent amylose content and swelling factor of flours. Gelatinization onset and peak temperatures increased after germination, while a slight decrease was found in conclusion temperature. Compared to the raw flours, the germinated flours derived from brown rice, sorghum, and millet had lower gelatinization enthalpy, whereas the germinated oat flour showed higher gelatinization enthalpy. Germination resulted in significant decrease in pasting parameters of the four flours. Amylose leaching of sorghum and millet flours increased after germination, while the brown rice and oat flours showed a significant decrease in amylose leaching. Results suggest that germination effectively altered the physicochemical properties of grain flours, which can be utilized as functional ingredient in the preparation of grain-based products.

An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid

Gamma-aminobutyric acid (Gaba) is a non-proteinogenic amino acid that is widely present in microorganisms, plants, and vertebrates. So far, Gaba is well known as a main inhibitory neurotransmitter in the central nervous system. Its physiological roles are related to the modulation of synaptic transmission, the promotion of neuronal development and relaxation, and the prevention of sleeplessness and depression. Besides, various pharmaceutical properties of Gaba on non-neuronal peripheral tissues and organs were also reported due to anti-hypertension, anti-diabetes, anti-cancer, antioxidant, anti-inflammation, anti-microbial, anti-allergy, hepato-protection, reno-protection, and intestinal protection. Therefore, Gaba may be considered as potential alternative therapeutics for prevention and treatment of various diseases. Accordingly, this updated review was mainly focused to describe the pharmaceutical properties of Gaba as well as emphasize its important role regarding human health.

An efficient process for co-production of γ-aminobutyric acid and probiotic Bacillus subtilis cells

This study was to establish an integrated process for the co-production of γ-aminobutyric acid (GABA) and live probiotics. Six probiotic bacteria were screened and Bacillus subtilis ATCC 6051 showed the highest GABA-producing capacity. The optimal temperature and initial pH value for GABA production in B. subtilis were found to be 30 °C and 8.0, respectively. A variety of carbon and nitrogen sources were tested, and potato starch and peptone were the preferred carbon and nitrogen sources for GABA production, respectively. The concentrations of carbon source, nitrogen source and substrate (sodium l-glutamate) were then optimized using the response surface methodology. The GABA titer and concentration of viable cells of B. subtilis reached 19.74 g/L and 6.0 × 108 cfu/mL at 120 h. The GABA titer represents the highest production of GABA in B. subtilis. This work thus demonstrates a highly efficient co-production process for GABA and probiotic B. subtilis cells.

Antihypertensive Effect of γ-Aminobutyric Acid-Enriched Brown Rice on Spontaneously Hypertensive Rats

'Haiibuki' is a giant embryo rice cultivar that contains abundant γ-aminobutyric acid (GABA) compared with conventional rice cultivars. Here, we performed a functional evaluation of 'GABA-enriched brown rice' (GEBR) prepared by modifying the 'Haiibuki' cultivar to contain more GABA. Study 1: Spontaneously hypertensive rats were divided into three groups [control (cornstarch), normal brown rice, and GEBR] and fed an orally administered diet for 4 wk. A significant blood pressure elevation-inhibitory effect was observed in the GEBR group as compared with the other groups. Study 2: Rats were divided into two groups and fed ad libitum for 12 wk. The two groups were control (commercial feed with 5% cornstarch) and GEBR (commercial feed with 5% GEBR). Body weight, blood pressure, food consumption, and water intake were measured during the study period, and blood chemistry was analyzed after the study. Plasma 8-hydroxy-2'-deoxyguanosine (8-OHdG) and urinary isoprostane were measured 12 and 10 wk after the start of the study, respectively. A significant blood pressure elevation-inhibitory effect was observed in the GEBR group. The 8-OHdG and isoprostane levels were significantly lower in the GEBR group than in the control group, demonstrating an oxidative stress-reducing effect. Therefore, GEBR exhibited a blood pressure elevation-inhibitory effect under the conditions of this study. The antioxidative action may occur secondarily to the antihypertensive action of GABA, suggesting that the long-term ad libitum ingestion of GEBR prevents hypertension. A reduction in oxidative stress could reduce the chances of complications in cardiovascular diseases.

Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death in the world and our approach to the control and management of CVD mortality is limited. Nattokinase (NK), the most active ingredient of natto, possesses a variety of favourable cardiovascular effects and the consumption of Natto has been linked to a reduction in CVD mortality. Recent research has demonstrated that NK has potent fibrinolytic activity, antihypertensive, anti-atherosclerotic, and lipid-lowering, antiplatelet, and neuroprotective effects. This review covers the major pharmacologic effects of NK with a focus on its clinical relevance to CVD. It outlines the advantages of NK and the outstanding issues pertaining to NK pharmacokinetics. Available evidence suggests that NK is a unique natural compound that possesses several key cardiovascular beneficial effects for patients with CVD and is therefore an ideal drug candidate for the prevention and treatment of CVD. Nattokinase is a promising alternative in the management of CVD.

Production of antioxidant and ACE-inhibitory peptides from Kluyveromyces marxianus protein hydrolysates: Purification and molecular docking

Kluyveromyces marxianus protein hydrolysates were prepared by two different sonicated-enzymatic (trypsin and chymotrypsin) hydrolysis treatments to obtain antioxidant and ACE-inhibitory peptides. Trypsin and chymotrypsin hydrolysates obtained by 5 h, exhibited the highest antioxidant and ACE-inhibitory activities. After fractionation using ultra-filtration and reverse phase high performance liquid chromatography (RP-HPLC) techniques, two new peptides were identified. One fragment (LL-9, MW = 1180 Da) with the amino acid sequence of Leu-Pro-Glu-Ser-Val-His-Leu-Asp-Lys showed significant ACE inhibitory activity (IC₅₀ = 22.88 μM) while another peptide fragment (VL-9, MW = 1118 Da) with the amino acid sequence of Val-Leu-Ser-Thr-Ser-Phe-Pro-Pro-Lys showed the highest antioxidant and ACE inhibitory properties (IC₅₀ = 15.20 μM, 5568 μM TE/mg protein). The molecular docking studies revealed that the ACE inhibitory activities of VL-9 is due to interaction with the S2 (His513, His353, Glu281) and S’1 (Glu162) pockets of ACE and LL-9 can fit perfectly into the S1 (Thr345) and S2 (Tyr520, Lys511, Gln281) pockets of ACE.

Protective Effect of Salicornia europaea Extracts on High Salt Intake-Induced Vascular Dysfunction and Hypertension

High salt intake causes and aggravates arterial hypertension and vascular dysfunction. We investigated the effect of Salicornia europaea extracts (SE) on vascular function and blood pressure. SE constituents were analyzed using high performance liquid chromatography, and SE's effect on vascular function was evaluated in isolated porcine coronary arteries. SE's vascular protective effect was also evaluated in vivo using normotensive and spontaneous hypertensive rats (SHRs). SE mainly contained sodium chloride (55.6%), 5-(hydroxymethyl)furfural, p-coumaric acid, and trans-ferulic acid. High sodium (160 mmol/L) induced vascular dysfunction; however, SE containing the same quantity of sodium did not cause vascular dysfunction. Among the compounds in SE, trans-ferulic acid accounts for the vascular protective effect. Normotensive rats fed a high-salt diet showed significantly increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP), which decreased significantly in the SE-treated groups. In SHRs, high edible salt intake significantly increased SBP, DBP, and MAP, but SE intake was associated with a significantly lower MAP. Thus, SE did not induce vascular dysfunction, and trans-ferulic acid might be at least partly responsible for the vasoprotective effect of SE. Taken together, SE could be used as an alternative to purified salt to prevent and ameliorate hypertension.