Soy β-Conglycinin Peptide Attenuates Obesity and Lipid Abnormalities in Obese Model OLETF Rats

Functional improvements in β-conglycinin by preparing bioconjugates with carboxymethyl cellulose

β-Conglycinin was conjugated with carboxymethyl cellulose (CMC) by using water-soluble carbodiimide to improve its function. Two kinds of CMC differing in average molecular weight (about 1 kDa and 90 kDa) were used to investigate the relationship between molecular weight of conjugated saccharide and saccharide content in the conjugates and degree of functional changes in β-conglycinin. The β-conglycinin-CMC conjugates were purified by dialysis using a dialysis membrane whose molecular weight cutoff is 100 kDa. Composition of the β-conglycinin-low molecular weight (LMW) CMC and β-conglycinin-high molecular weight (HMW) CMC was β-conglycinin: CMC = 1:3.3 and 1:2.1 (weight ratio) respectively which was confirmed by BCA method and phenol sulfuric acid method. Conjugation was confirmed by SDS-PAGE with CBB. Solubility of β-conglycinin in the range of pH4.0-7.0 was much improved by conjugation with both LMW and HMW CMC. Emulsifying property of β-conglycinin at pH5.0 and pH7.0 was much improved by conjugation with HMW CMC and greater improvement was achieved by conjugation with LMW CMC. Immunogenicity of β-conglycinin was decreased by conjugation with LMW CMC.

Antioxidant Peptides from Miiuy Croaker Swim Bladders: Ameliorating Effect and Mechanism in NAFLD Cell Model through Regulation of Hypolipidemic and Antioxidant Capacity

In this work, the hypolipidemic and antioxidative capacity of FSGLR (S7) and GIEWA (S10) from miiuy croaker swim bladders was explored systematically in an oleic acid (OA)-induced nonalcoholic fatty liver disease (NAFLD) model of HepG2 cells. Moreover, the hypolipidemic activity of S7 and S10 and their antioxidative abilities were preliminarily investigated in combination with molecular docking technology. The results indicated that S7 and S10 could decrease the amount of lipid accumulation and the content of triglycerides (TG) and total cholesterol (TC) in the OA-induced NAFLD cell model in a dose-dependent manner. In addition, S7 and S10 exhibited better bile salt binding, pancreatic lipase (PL) inhibition, and cholesterol esterase (CE) inhibition capacities. The hypolipidemic mechanisms of S7 and S10 were connected with the downregulation of the mRNA expression levels of adipogenic factors, including sterol-regulatory element-binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), sterol-regulatory element-binding protein (SREBP)-2, hydroxymethylglutaryl-CoA reductase (HMGR), and fatty acid synthase (FAS) (p < 0.01), and the upregulation of the mRNA expression of β-oxidation-related factors, including carnitine palmitoyltransferase 1 (CPT-1), acyl-CoA oxidase 1 (ACOX-1), and peroxisome proliferator-activated receptor α (PPARα). Moreover, FSGLR (S7) and GIEWA (S10) could significantly protect HepG2 cells against OA-induced oxidative damage, and their antioxidant mechanisms were related to the increased activity of intracellular antioxidant proteases (superoxide dismutase, SOD; glutathione peroxidase, GSH-PX; catalase, CAT) to remove excess reactive oxygen species (ROS) and decrease the production of malondialdehyde (MDA). The presented findings indicate that the hypolipidemic and antioxidant functions and mechanisms of S7 and S10 could make them potential hypolipidemic and antioxidant candidates for the treatment of NAFLD.

Comprehensive review of plant-derived anti-hyperlipidemia peptides: Production, anti-hyperlipidemia mechanism, and structure-activity relationship study

Hyperlipidemia, an elevated level of cholesterol and/or triglycerides, has become a major public health problem worldwide. Although drugs intervention is effective in treating hyperlipidemia, most of them have adverse side effects. Peptides from natural plants with high anti-hyperlipidemic activity and a strong safety profile have emerged as promising candidates to prevent and ameliorate hyperlipidemia. This review summarizes the recent advances in plant-derived anti-hyperlipidemic peptides in terms of their sources, production, purification, identification, and activity evaluation. The focus is extended to their potential anti-hyperlipidemic mechanisms and structure-function relationships. Bioactive peptides derived from various plant sources, especially peptides containing hydrophobic and/or acidic amino acids, have shown remarkable effects in hyperlipidemic treatment. Their anti-hyperlipidemic effects are mediated by various mechanisms, including regulation of cholesterol metabolism and triglyceride metabolism, inhibition of inflammation-related metabolic syndrome, and modulation of the gut microbiota. Further evaluation of the stability, bioavailability, and clinical efficacy of these peptides is recommended.

Anti-obesity and anti-diabetic bioactive peptides: A comprehensive review of their sources, properties, and techno-functional challenges

The scourge of obesity arising from obesogens and poor dieting still ravages our planet as half of the global population may be overweight and obese by 2035. This metabolic disorder is intertwined with type 2 diabetes (T2D), both of which warrant alternative therapeutic options other than clinically approved drugs like orlistat with their tendency of abuse and side effects. In this review, we comprehensively describe the global obesity problem and its connection to T2D. Obesity, overconsumption of fats, the mechanism of fat digestion, obesogenic gut microbiota, inhibition of fat digestion, and natural anti-obesity compounds are discussed. Similar discussions are made for diabetes with regard to glucose regulation, the diabetic gut microbiota, and insulinotropic compounds. The sources and production of anti-obesity bioactive peptides (AOBPs) and anti-diabetic bioactive peptides (ADBPs) are also described while explaining their structure-function relationships, gastrointestinal behaviors, and action mechanisms. Finally, the techno-functional applications of AOBPs and ADBPs are highlighted.

Production of Food-Derived Bioactive Peptides with Potential Application in the Management of Diabetes and Obesity: A Review

The prevalence of diabetes mellitus and obesity is increasing worldwide. Bioactive peptides are naturally present in foods or in food-derived proteins. Recent research has shown that these bioactive peptides have an array of possible health benefits in the management of diabetes and obesity. First, this review will summarize the top-down and bottom-up production methods of the bioactive peptides from different protein sources. Second, the digestibility, bioavailability, and metabolic fate of the bioactive peptides are discussed. Last, the present review will discuss and explore the mechanisms by which these bioactive peptides help against obesity and diabetes based on in vitro and in vivo studies. Although several clinical studies have demonstrated that bioactive peptides are beneficial in alleviating diabetes and obesity, more double-blind randomized controlled trials are needed in the future. This review has provided novel insights into the potential of food-derived bioactive peptides as functional foods or nutraceuticals to manage obesity and diabetes.

The Beneficial Effects of Soybean Proteins and Peptides on Chronic Diseases

With lifestyle changes, chronic diseases have become a public health problem worldwide, causing a huge burden on the global economy. Risk factors associated with chronic diseases mainly include abdominal obesity, insulin resistance, hypertension, dyslipidemia, elevated triglycerides, cancer, and other characteristics. Plant-sourced proteins have received more and more attention in the treatment and prevention of chronic diseases in recent years. Soybean is a low-cost, high-quality protein resource that contains 40% protein. Soybean peptides have been widely studied in the regulation of chronic diseases. In this review, the structure, function, absorption, and metabolism of soybean peptides are introduced briefly. The regulatory effects of soybean peptides on a few main chronic diseases were also reviewed, including obesity, diabetes mellitus, cardiovascular diseases (CVD), and cancer. We also addressed the shortcomings of functional research on soybean proteins and peptides in chronic diseases and the possible directions in the future.

Functional improvements in β-conglycinin by edible bioconjugation with carboxymethyl dextran

β-Conglycinin was conjugated with carboxymethyl dextran (CMD) by the Maillard reaction to improve its function. The β-conglycinin-CMD conjugate was purified by dialysis. Conjugation was confirmed by SDS-PAGE with CBB and PAS staining. Composition of the β-conglycinin-CMD was β-conglycinin:CMD = 1:2.7 (molar ratio) which was confirmed by BCA method and phenol sulfuric acid method. Solubility of β-conglycinin in the range of pH 2.0-7.0 was much improved by conjugation with CMD. Emulsifying property of β-conglycinin at pH 7 and in presence of salt was improved by conjugation with CMD. Immunogenicity of β-conglycinin was reduced by conjugation with CMD. Conjugation method performed in this study was considered to be valuable in that it can be used in food processing.

ε

β-Conglycinin was conjugated with ε-polylysine (PL) by means of microbial transglutaminase (MTGase) to improve its function. The β-conglycinin-PL conjugate was purified by dialysis. Composition of the β-conglycinin-PL was β-conglycinin:PL = 1:18 (molar ratio) which was confirmed by amino acid analysis. The β-conglycinin-PL was further conjugated with dextran (Dex) by the Maillard reaction. The β-conglycinin-PL-Dex conjugate was purified by dialysis. Conjugation was confirmed by SDS-PAGE and PAS staining. Composition of the β-conglycinin-PL-Dex was β-conglycinin-PL:Dex = 1:41 (molar ratio) which was confirmed by UV spectra measurement and phenol sulfuric acid method. Solubility of β-conglycinin in the acidic range was much improved by conjugation with PL and further improved by further conjugation with Dex. Emulsifying property of β-conglycinin in acidic pH range was much improved by conjugation with PL and Dex. Immunogenicity of β-conglycinin was decreased by conjugation with PL and Dex.

Hypolipidemic Effects of Soy Protein and Isoflavones in the Prevention of Non-Alcoholic Fatty Liver Disease- A Review

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and affects about 25% of the population globally. Obesity and diabetes are the main causes of the disease characterized by excessive accumulation of lipids in the liver. There is currently no direct pharmacological treatments for NAFLD. Dietary intervention and lifestyle modification are the key strategies in the prevention and treatment of the disease. Soy consumption is associated with many health benefits such as decreased incidence of coronary heart disease, type-2 diabetes, atherosclerosis and obesity. The hypolipidemic functions of soy components have been shown in both animal studies and human clinical trials. Dietary soy proteins and associated isoflavones suppressed the formation and accumulation of lipid droplets in the liver and improved NAFLD-associated metabolic syndrome. The molecular mechanism(s) underlying the effects of soy components are mainly through modulation of transcription factors, sterol regulatory element-binding protein-1 and peroxisome proliferator-activated receptor-γ2, and expressions of their target genes involved in lipogenesis and lipolysis as well as lipid droplet-promoting protein, fat-specific protein-27. Inclusion of appropriate amounts of soy protein and isoflavones in the diets might be a useful approach to decrease the prevalence of NAFLD and mitigate disease burden.

Bioactive Peptides: From Basic Research to Clinical Trials and Commercialization

Chronic diseases, including metabolic diseases, have become a worldwide public health issue. Research regarding the use of bioactive peptides or protein hydrolysates derived from food, as the diet-based strategies for the prevention and mitigation of chronic diseases, has increased exponentially in the past decades. Numerous in vitro and in vivo studies report the efficacy and safety of food-derived bioactive peptides and protein hydrolysates as antihypertensive, anti-inflammatory, antidiabetic, and antioxidant agents. However, despite promising preclinical results, an inadequate understanding of their mechanisms of action and pharmacokinetics restrict their clinical translation. Commercialization of bioactive peptides can be further hindered due to scarce information regarding their efficacy, safety, bitter taste, as well as the lack of a cost-effective method of production. This review provides an overview of the current clinical evidence and challenges to commercial applications of food-derived bioactive peptides and protein hydrolysates for the prevention and alleviation of chronic diseases.

Association between Equol Production Status and Nonalcoholic Steatohepatitis

Equol is a metabolite of daidzein, a major soybean isoflavone with estrogenic and antioxidant activities. As the production of equol depends on the presence of certain members of the intestinal microflora, not all individuals can produce equol. We examined the relationship between NASH histological features and equol production. In an animal model, obese OLETF rats were intraperitoneally injected with a porcine serum to augment liver fibrogenesis. Equol-rich soy product, SE5-OH was orally administered during the experimental period. Treatment with SE5-OH markedly attenuated the development of liver fibrosis and expression of alpha-smooth muscle actin. In clinical research, 38 NAFLD patients (13 men and 25 women) were included. The degree of fibrosis and ballooning in equol-nonproducers was significantly higher than in equol-producers in women. The percentage of nonproducers with NAFLD activity score (NAS) ≥ 5 was significantly higher than that of producers. None of the histological features were significantly different between nonproducers and producers in men. Decision tree analysis identified predictors for NAS ≥ 5 in women. The status of equol production was the strongest predictor, followed by fasting glucose. Since equol can be noninvasively detected in urine, it can be applied as a screening tool for the progression of NASH in women.