Black Soybean and Adzuki Bean Extracts Lower Blood Pressure by Modulating the Renin-Angiotensin System in Spontaneously Hypertensive Rats

A Comprehensive Review of the Chemical Constituents and Functional Properties of Adzuki Beans (Vigna angulariz)

The adzuki bean (Vigna angulariz), a member of the Vigna genus within the Leguminosae family, is native to China and extensively cultivated across East Asia. Renowned for its rich nutritional profile, the adzuki bean is abundant in carbohydrates, proteins, and bioactive compounds such as polysaccharides, polyphenols, flavonoids, saponins, and peptides. These components confer a wide range of health-promoting properties, including potent antioxidant, anti-inflammatory, antidiabetic, antiobesity, antibacterial, and neuroprotective effects. Notably, adzuki beans exhibit unique functional properties, such as high resistant starch content and the ability to modulate gut microbiota by promoting beneficial bacteria like Akkermansia, which enhance insulin sensitivity and lipid metabolism. These attributes make adzuki beans particularly effective in managing chronic diseases such as diabetes, obesity, and cardiovascular disorders. Additionally, adzuki beans show promise in addressing conditions like muscle atrophy, osteoporosis, and cancer. Processing methods such as fermentation and heat treatment further enhance their bioactive potential, underscoring their suitability for developing functional foods and nutraceuticals. This review highlights the chemical composition, functional activities, and mechanisms of adzuki beans, providing valuable insights for their application in food and pharmaceutical industries to prevent and manage chronic diseases.

Phenolic Compounds and Anthocyanins in Legumes and Their Impact on Inflammation, Oxidative Stress, and Metabolism: Comprehensive Review

Inflammation, oxidative stress, and metabolic diseases are intricately linked in a complex, self-reinforcing relationship. Inflammation can induce oxidative stress, while oxidative stress can trigger inflammatory responses, creating a cycle that contributes to the development and progression of metabolic disorders; in addition, these effects can be observed at systemic and local scales. Both processes lead to cellular damage, mitochondrial dysfunction, and insulin resistance, particularly affecting adipose tissue, the liver, muscles, and the gastrointestinal tract. This results in impaired metabolic function and energy production, contributing to conditions such as type 2 diabetes, obesity, and metabolic syndrome. Legumes are a good source of phenolic compounds and anthocyanins that exert an antioxidant effect-they directly neutralize reactive oxygen species and free radicals, reducing oxidative stress. In vivo, in vitro, and clinical trial studies demonstrate that these compounds can modulate key cellular signaling pathways involved in inflammation and metabolism, improving insulin sensitivity and regulating lipid and glucose metabolism. They also exert anti-inflammatory effects by inhibiting proinflammatory enzymes and cytokines. Additionally, anthocyanins and phenolics may positively influence the gut microbiome, indirectly affecting metabolism and inflammation.

Black beans (Glycine max (L.) Merrill) included in a multi-grain rice reduce total cholesterol and enhance antioxidant capacity in high-fat diet-induced obese mice

This study investigated the effects of black bean (BB) supplementation on the growth performance, lipid metabolism, and antioxidant capacity of high-fat diet-induced obese mice. The results demonstrated that although the inclusion of BBs led to increased body weight, total energy intake, and feed efficiency ratio, it did not significantly alter the overall body composition, including adiposity. Notably, BB consumption reduced total cholesterol levels, suggesting its potential to manage dyslipidemia and reduce the risk of atherosclerotic cardiovascular diseases. Furthermore, BBs significantly enhanced in the total antioxidant capacity, as indicated by the notable increase in both the total antioxidant capacity and superoxide dismutase activity. These findings provide significant insights into the promising health benefits of BBs in the context of metabolic syndrome and related health complications.

Association between socio-demographic factors, lifestyle, eating habits and hypertension risk among middle-aged and older rural Chinese adults

BACKGROUND AND AIMS

Hypertension is a global health issue with increasing prevalence. This study aimed to understand the epidemiological characteristics and influencing factors of hypertension in rural Chinese populations and help develop effective prevention and control strategies.

METHODS AND RESULTS

This cross-sectional study used database from the Early Diagnosis and Early Treatment Project of Esophageal Cancer conducted in a rural population from September 2012 to December 2017. A total of 10,111 subjects aged 35-75 years residing in Huai'an District, Huai'an City, Jiangsu Province for at least three years were included. Unconditional univariate and multivariate logistic regression models were performed to evaluate the association between socio-demographic information, lifestyle habits, dietary characteristics and the risk of hypertension. The prevalence of hypertension was 34.32 % in this rural population. Men and older individuals are more likely to have hypertension when compared with women and young individuals, respectively. Factors associated with an increased risk of hypertension included: fast eating speed, a high-salt diet (both currently and ten years ago), a high-spicy diet ten years ago, high BMI, poor educational attainment, preference for fatty meats, hot diet, green tea drinking, intake of pickled potherb mustard and corn flour, family smoking and alcohol consumption. Light smoking in males, consumption of fruits, adzuki bean, and pork liver were associated with reduced risk of hypertension.

CONCLUSIONS

The study identified some factors, including eat habits and lifestyle, associated with hypertension risk, and highlighted the need for targeted policies and interventions in rural China to address potential risk factors for hypertension.

Comparison of the anti-diabetic effects of various grain and legume extracts in high-fat diet and streptozotocin-nicotinamide-induced diabetic rats

The anti-diabetic properties of whole groats and dietary fibers from various grains and legumes are well known. Nevertheless, studies on the anti-diabetic effects of their extracts are limited, and it is difficult to compare their efficacy. This study investigated the anti-diabetic potential of ethanol extracts from oats (OE), sorghum (SE), foxtail millet (FE), proso millet (PE), adzuki bean (AE), and black soybean (BE) in a high-fat diet and streptozotocin-nicotinamide-induced diabetic rat models. The extracts, obtained using 99.9 % ethanol, were orally administered to diabetic rats for four weeks. Various parameters were evaluated, including fasting blood glucose levels, glucose tolerance, insulin sensitivity, serum insulin levels, and pancreas histological analysis. OE and SE effectively reduced fasting blood glucose levels and the area under the curve (AUC) in the oral glucose tolerance test. Only OE significantly decreased the AUC in the insulin tolerance test and increased insulin concentration and homeostatic model assessment of the β-cell function index, indicating improved insulin sensitivity and β-cell function. Histological and immunohistochemical analysis of the pancreas supported these findings, demonstrating that OE protected against pancreatic cell damage. In contrast, FE, PE, AE, and BE did not have a significant effect on diabetes-related parameters. These findings identify OE as the most promising natural intervention for diabetes management.

Antihypertensive effects of the combined extract of Sorghum bicolor, Vigna angularis, and Eleusine coracana in spontaneously hypertensive rats

This study investigated the antihypertensive effects of the combined extract of sorghum, adzuki bean, and finger millet (SAFE) on spontaneously hypertensive rats. The rats were divided into four groups (n = 8): WKY, SHR, SAFE (500 mg/kg SAFE), and CAP (50 mg/kg captopril). SAFE significantly decreased the lean-to-fat mass ratio with no notable changes in body weight, food intake, or food efficiency ratio, and it effectively lowered both systolic and diastolic blood pressures, comparable to CAP. Moreover, it significantly reduced the cardiac mass index and alleviated cardiac fibrosis. SAFE did not induce hepatotoxicity, as indicated by the maintenance of aspartate aminotransferase and alanine aminotransferase levels in the normal range, confirming its safety. Taken together, these findings suggested that SAFE can be used as a dietary supplement for blood pressure regulation and cardiovascular disease prevention.

Hypotensive and Endothelium-Dependent Vasorelaxant Effects of Grayblue Spicebush Ethanol Extract in Rats

Hypertension is one of the most common chronic diseases, and its prevalence is increasing worldwide. Lindera glauca (Siebold & Zucc.) Blume, known as grayblue spicebush (GS), has been used as food and for medicinal purposes; however, studies about its hypotensive or vasorelaxant effects are lacking. Therefore, the hypotensive effect of an ethanolic extract of the GS branch (GSE) was investigated in 15-week-old spontaneously hypertensive rats (SHRs) using the tail cuff method. The GSE administration group (1000 mg/kg SHR body weight) showed a decrease in their systolic and diastolic blood pressure measured 4 h after its administration. In addition, we investigated its vasorelaxant effect using the thoracic aorta dissected from Sprague-Dawley rats. The GSE (0.5, 1, 2, 5, 10, and 20 μg/mL) showed an endothelium-dependent vasorelaxant effect, and its mechanisms were found to be relevant to the inward rectifier, voltage-dependent, and non-selective K+ channels. Moreover, the GSE (20 μg/mL) showed an inhibitory effect on aortic rings constricted with angiotensin II. Considering its hypotensive and vasorelaxant effects, GSE has potential as a functional food to help treat and prevent high blood pressure. However, further studies on the identification of the active components of GSE and safety evaluations of its use are needed.

Nutritional Potential of Adzuki Bean Germplasm and Mining Nutri-Dense Accessions through Multivariate Analysis

The adzuki bean (Vigna angularis), known for its rich nutritional composition, holds significant promise in addressing food and nutritional security, particularly for low socioeconomic classes and the predominantly vegetarian and vegan populations worldwide. In this study, we assessed a total of 100 diverse adzuki bean accessions, analyzing essential nutritional compounds using AOAC's official analysis procedures and other widely accepted standard techniques. Our analysis of variance revealed significant genotype variations for all the traits studied. The variability range among different traits was as follows: moisture: 7.5-13.3 g/100 g, ash: 1.8-4.2 g/100 g, protein: 18.0-23.9 g/100 g, starch: 31.0-43.9 g/100 g, total soluble sugar: 3.0-8.2 g/100 g, phytic acid: 0.65-1.43 g/100 g, phenol: 0.01-0.59 g/100 g, antioxidant: 11.4-19.7 mg/100 g GAE. Noteworthy accessions included IC341955 and EC15256, exhibiting very high protein content, while IC341957 and IC341955 showed increased antioxidant activity. To understand intertrait relationships, we computed correlation coefficients between the traits. Principal Component Analysis (PCA) revealed that the first four principal components contributed to 63.6% of the variation. Further, hierarchical cluster analysis (HCA) identified nutri-dense accessions, such as IC360533, characterized by high ash (>4.2 g/100 g) and protein (>23.4 g/100 g) content and low phytic acid (0.652 g/100 g). These promising compositions provide practical support for the development of high-value food and feed varieties using effective breeding strategies, ultimately contributing to improved global food security.

Effects of aurantiamide on a rat model of renovascular arterial hypertension

Asperglaucide (ASP) is an aurantiamide, an effective constituent of purslane (Portulaca oleracea L.), a safe to eat greenery. Effects of ASP on endothelial function, endothelial nitric oxide synthase (eNOS) expression, vascular fluidity, renal and vascular reactive oxygen, and nitrogen species (ROS/RNS) production was examined in the two-kidney one-clip (2 K-1C) rat model of renovascular arterial hypertension. ASP toxicity, dose dependent eNOS gene expression and protein levels were also analyzed in human umbilical vein endothelial cells (HUVEC). The 2 K-1C model of hypertension was created via surgery and mean blood pressure (MBP) was measured by tail-cuff method during four weeks of ASP treatment. Erythrocyte deformability was monitored by rotational ektacytometry, while vascular constrictor and dilator responses were determined in organ baths. eNOS gene expression and protein levels were assessed in thoracic aorta and HUVEC. MBP was significantly decreased in hypertensive rats treated with ASP. Endothelium dependent vascular dilator and constrictor responses were also considerably improved following ASP treatment. There was a notable increase in red blood cell deformability in hypertensive rats treated with ASP as compared to hypertensive rats alone. A significant increase was observed in eNOS gene expression and protein levels in both normotensive and hypertensive rats treated with ASP. Treatment of HUVEC with 3 µM ASP notably increased eNOS mRNA and protein levels. In conclusion, ASP lowered blood pressure, improved endothelium-mediated relaxation, decreased renovascular ROS/RNS production in hypertensive rats. ASP also increased eNOS protein expression in aorta and HUVEC at nontoxic doses. ASP may have future potential as an anti-hypertensive agent.

Effects of in vitro digestion on protein degradation, phenolic compound release, and bioactivity of black bean tempeh

The nutritional value and bioactivity of black beans are enhanced when fermented as tempeh, but their bioaccessibility and bioactivity after ingestion remain unclear. In this study, black bean tempeh and unfermented black beans were digested in vitro and changes in protein degradation, phenolic compound release, angiotensin I-converting enzyme (ACE)-inhibitory activity, and antioxidant activity between the two groups were compared. We observed that the soluble protein content of digested black bean tempeh was generally significantly higher than that of digested unfermented black beans at the same digestion stage (P < 0.05). The degree of protein hydrolysis and the content of <10 kDa peptides were also significantly higher in the digested black bean tempeh than in digested unfermented black beans (P < 0.05). SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis showed that most macromolecular proteins in tempeh had been degraded during fermentation and more of the small peptides were released from black bean tempeh during digestion, respectively. Compared to that of the unfermented black beans, the level of ACE inhibition of black bean tempeh was lower, but this significantly increased to 82.51% following digestion, closing the gap with unfermented black beans. In addition, the total respective levels of phenolics, flavonoids, and proanthocyanidins released from black bean tempeh were 1.21, 1.40, and 1.55 times those of unfermented black beans following in vitro digestion, respectively. Antioxidant activity was also significantly higher in digested black bean tempeh than in digested unfermented black beans and showed a positive correlation with phenolic compound contents (P < 0.05). The results of this study proved that, compared to unfermented black beans, black bean tempeh retained protein and phenolic compound bioaccessibility and antioxidant activity and showed an improved ACE-inhibitory activity even after consumption.

Variability of Anthocyanin Concentrations, Total Metabolite Contents and Antioxidant Activities in Adzuki Bean Cultivars

In this study, adzuki bean cultivars including Arari, Chilbopat, Geomguseul, and Hongeon were recently cultivated, and the concentrations of seven individual anthocyanins were determined in their seed coats for the first time. Moreover, the variations of total saponin content (TSC), total phenolic content (TPC), 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, Trolox equivalent antioxidant capacity (TEAC), and ferric reducing antioxidant power (FRAP) between defatted and undefatted extracts of whole seeds, seed coats, and dehulled seeds of each were analyzed. The anthocyanins were detected only in the black seed-coated cultivars and delphinidin-3-O-glucoside was dominant in both Geomguseul (12.46 mg/g) and Chilbopat (10.88 mg/g) followed by delphinidin-3-O-galactoside. TSC and TPC were in the ranges of 16.20−944.78 mg DE/g and 0.80−57.35 mg GAE/g, respectively, and each decreased in the order of seed coats > whole seeds > dehulled seeds regardless of extract type. The antioxidant activities also showed similar patterns of variation. Geomguseul seed coats outweighed the remaining cultivars in terms of TPC and FRAP activity (p < 0.05). Generally, significant variations of metabolite contents and antioxidant activities were observed between cultivars and across their seed parts (p < 0.05). Thence, black seed-coated adzuki beans could be excellent sources of anthocyanins and antioxidants.

Development of a method to screen and isolate xanthine oxidase inhibitors from black bean in a single step: Hyphenation of semipreparative liquid chromatography and stepwise flow rate countercurrent chromatography

Black bean, in which isoflavones are the main active constituent, also contains saponins and monoterpenes. Soybean isoflavone is a secondary metabolite that is formed during the growth of soybean; it exhibits antioxidant and cardiovascular activities and traces estrogen-like effects. In this study, black bean isoflavones were extracted with n-butanol, and ultrafiltration-liquid chromatography-mass spectrometry was used to screen their activity. Subsequently, the inhibitors were isolated and purified using semipreparative liquid chromatography and stepwise flow rate countercurrent chromatography. Thereafter, five active compounds were identified using mass spectrometry and nuclear magnetic resonance experiments. Finally, the inhibition types of the xanthine oxidase inhibitors were determined using enzymatic kinetic studies. The IC₅₀ values of daidzin, glycitein-7-O-glucoside, genistin, daidzein, and genistein were determined to be 35.08, 56.22, 30.76, 68.79, and 95.37 μg/mL, respectively. Daidzin, genistin, and daidzein exhibited reversible inhibition, whereas glycitein-7-O-glucoside and genistein presented irreversible inhibition. This novel approach, which was based on ultrafiltration-liquid chromatography-mass spectrometry and stepwise flow rate countercurrent chromatography, is a powerful method for screening and isolating xanthine oxidase inhibitors from complex matrices. The study of enzyme inhibition types is helpful for understanding the underlying inhibition mechanism. Therefore, a beneficial platform was developed for the large-scale production of bioactive and nutraceutical ingredients.