Identification of pyroglutamyl peptides with anti-colitic activity in Japanese rice wine, sake, by oral administration in a mouse model

Structure and regulatory mechanisms of food-derived peptides in inflammatory bowel disease: A review

The number of patients with inflammatory bowel disease (IBD) is increasing worldwide. Since IBD is a chronic disease that seriously affects patients' life quality, preventing and alleviating IBD with natural and less side effect substances has become a research hotspot. Food-derived bioactive peptides have been an attractive research focus due to their high efficiency and low toxicity. This paper comprehensively summarizes food-derived peptides with intestinal health effects, focusing on peptide sequences with IBD-regulatory effects and emphasizing the effects of their structure and physicochemical properties such as peptide length, amino acid composition, and net charge on their function. We also analyzed its regulatory mechanisms, mainly in 5 aspects: modulating the intestinal microbiota, decreasing intestinal epithelial permeability, increasing antioxidant ability, regulating the expression of inflammatory cytokines, and targeting signaling pathways. This review will help establish novel, efficient screening methods for IBD-regulatory peptides and contribute to further research and discovery of them.

Liposome-embedded SOD attenuated DSS-induced ulcerative colitis in mice by ameliorating oxidative stress and intestinal barrier dysfunction

Oxidative stress is generally considered inseparable from the development and exacerbation of ulcerative colitis (UC). Therefore, reducing oxidative stress has become a possible way to alleviate UC. In this study, the therapeutic effects of different doses of liposome-embedded superoxide dismutase (L-SOD) on mice with DSS-induced UC were systematically investigated. The results showed that L-SOD significantly attenuated the signs of colitis in mice, including colonic shortening, diarrhoea, bloody stools, and histopathological changes. L-SOD ameliorated DSS-induced oxidative damage, increased SOD, catalase (CAT), and glutathione (GSH) activities, and decreased malondialdehyde (MDA) levels. In addition, L-SOD ameliorated the inflammatory response by inhibiting the expression of myeloperoxidase (MPO) and pro-inflammatory cytokines and protected barrier function by promoting the expression of the tight junction proteins occludin and ZO-1 in the colon. Importantly, the results demonstrated a bell-shaped distribution of therapeutic effects relative to the administered dose, with an optimal dose of 150 000 U kg^-1. These results indicate that L-SOD has great potential as an ingredient in functional foods for the prevention and mitigation of UC.

Prevention and potential repair of colitis: Beneficial effects and regulatory mechanisms of food-derived anti-inflammatory peptides

Intestinal inflammatory diseases are increasingly prevalent worldwide, and their pathogenesis is still not fully understood. As of late, studies have discovered that food-derived peptides have specific anti-inflammatory activity and can play a positive role in intestinal health. At the same time, it has broad application prospects in the prevention and treatment of colitis because of its wide source, fast absorption, and high safety. This article reviews the structure-activity and quantity-effect relationships of food-derived peptides for their anti-inflammatory effects. It then discusses their mechanism of action in inhibiting colitis from four aspects. Food-derived anti-inflammatory peptides can delay the progression of the disease by stimulating innate immunity, inhibiting inflammation, and promoting wound healing. Further experiments showed that food-derived anti-inflammatory peptides could prevent and treat colitis through four mechanisms: (a) regulation of inflammatory cytokines; (b) regulation of inflammatory pathways; (c) regulation of intestinal epithelial barrier; (d) regulation of intestinal flora balance. However, due to the treatment of colitis having limitations, there is an urgent to develop food-derived anti-inflammatory peptides as a treatment or adjunctive treatment for colitis. This review highlights the positive effects of food-derived peptides on colitis and anticipates the appearance of mitigating peptides for the therapy of colitis.

Induction of Endogenous Antimicrobial Peptides to Prevent or Treat Oral Infection and Inflammation

Antibiotics are often used to treat oral infections. Unfortunately, excessive antibiotic use can adversely alter oral microbiomes and promote the development of antibiotic-resistant microorganisms, which can be difficult to treat. An alternate approach could be to induce the local transcription and expression of endogenous oral antimicrobial peptides (AMPs). To assess the feasibility and benefits of this approach, we conducted literature searches to identify (i) the AMPs expressed in the oral cavity; (ii) the methods used to induce endogenous AMP expression; and (iii) the roles that expressed AMPs may have in regulating oral inflammation, immunity, healing, and pain. Search results identified human neutrophil peptides (HNP), human beta defensins (HBD), and cathelicidin AMP (CAMP) gene product LL-37 as prominent AMPs expressed by oral cells and tissues. HNP, HBD, and LL-37 expression can be induced by micronutrients (trace elements, elements, and vitamins), nutrients, macronutrients (mono-, di-, and polysaccharides, amino acids, pyropeptides, proteins, and fatty acids), proinflammatory agonists, thyroid hormones, and exposure to ultraviolet (UV) irradiation, red light, or near infrared radiation (NIR). Localized AMP expression can help reduce infection, inflammation, and pain and help oral tissues heal. The use of a specific inducer depends upon the overall objective. Inducing the expression of AMPs through beneficial foods would be suitable for long-term health protection. Additionally, the specialized metabolites or concentrated extracts that are utilized as dosage forms would maintain the oral and intestinal microbiome composition and control oral and intestinal infections. Inducing AMP expression using irradiation methodologies would be applicable to a specific oral treatment area in addition to controlling local infections while regulating inflammatory and healing processes.

Impact of food-derived bioactive peptides on gut function and health

The gastrointestinal tract (GIT) is the largest interface between our body and the environment. It is an organ system extending from the mouth to the anus and functions for food intake, digestion, transport and absorption of nutrients, meanwhile providing protection from environmental factors, like toxins, antigens, and pathogens. Diet is one of the leading factors modulating the function of the GIT. Bioactive peptides presenting naturally in food or derived from food proteins during digestion or processing have been revealed multifunctional in diverse biological processes, including maintaining gut health and function. This review summarizes the available evidence regarding the effects of food-derived bioactive peptides on gut function and health. Findings and insights from studies based on in vitro and animal models are discussed. The gastrointestinal mucosa maintains a delicate balance between immune tolerance to nutrients and harmful components, which is crucial for the digestive system's normal functions. Dietary bioactive peptides positively impact gastrointestinal homeostasis by modulating the barrier function, immune responses, and gut microbiota. However, there is limited clinical evidence on the safety and efficacy of bioactive peptides, much less on the applications of dietary peptides for the treatment or prevention of diseases related to the GIT. Further study is warranted to establish the applications of bioactive peptides in regulating gut health and function.

Peptides in Brewed Wines: Formation, Structure, and Function

The traditional low-alcoholic beverages, such as grape wine, sake, and rice wine, have been consumed all over the world for thousands of years, each with their unique methods of production that have been practiced for centuries. Moderate consumption of wine is generally touted as beneficial for health, although there is ongoing debate for the responsible components in wine. In this review, the structural and functional characteristics, the formation mechanisms, and their health-promoting activities of peptides in three brewed wines, grape wine, Chinese rice wine (also called Chinese Huangjiu or Chinese yellow wine), and Japanese sake, are discussed. The formation of peptides in wine imparts sensorial, technological, and biological attributes. Prospects on future research, with an emphasis on the peptide characterization, formation mechanism, physiological activity, and molecular mechanisms of action, are presented.

Effect of heating on the digestibility of isolated hempseed (Cannabis sativa L.) protein and bioactivity of its pepsin-pancreatin digests

The objective was to investigate the effects of heat pretreatment and simulated gastrointestinal digestion on potential antioxidant, anticancer and anti-inflammatory activities of hempseed (Cannabis sativa L.) proteins. Unheated isolated hempseed protein (IHP) and its heated counterparts (100 °C, 15 min and 30 min, termed as HP15D and HP30D) were hydrolyzed sequentially with pepsin and pancreatin and analyzed for digestibility and bioactivity (antioxidant, anti-proliferative and anti-inflammatory properties). Heat pretreatment led to an increase of low molecular weight proteins and degree of hydrolysis, and decrease of concentration of soluble protein, which means heat pretreated can significantly improve the digestibility of IHP. Pepsin-pancreatin digests released from heat pretreated IHP possessed less antioxidant, antiproliferative and anti-inflammatory properties than digests from unheated IHP. In conclusion, heat pre-treatment improved the digestibility of IHP but the resulting digests from heated IHP had lower bioactivity.

Presence of Exopeptidase-Resistant and Susceptible Peptides in a Bacterial Protease Digest of Corn Gluten

Corn gluten hydrolysate (CGH) was prepared by food-grade bacterial proteases, alcalase and neutral protease. Digestion of CGH with carboxypeptidase A and leucine aminopeptidase extensively changed the elution patterns of peptides as observed from reversed phase high performance liquid chromatography-mass spectrometry (LC-MS), whereas digestion with pepsin and trypsin hardly affected the elution patterns. Twenty-five major peptides in CGH were identified. After digestion with exopeptidases, only prolyl dipeptides and pyroglutamyl di- and tripeptides remained, whereas the other 17 peptides completely disappeared. On the other hand, all 25 peptides remained after digestion with pepsin and trypsin. These facts suggest that a majority of short-chain peptides in food protein hydrolysates are degraded by exopeptidases during digestion and absorption processes. Thus, susceptibility to exopeptidases should be considered for prediction of bioactive peptide upon ingestion, which has not been considered in most of previous studies on food-derived bioactive peptides.

Pyroglutamyl leucine, a peptide in fermented foods, attenuates dysbiosis by increasing host antimicrobial peptide

PyroGlu-Leu is present in certain food protein hydrolysates and traditional Japanese fermented foods. Our previous study demonstrated that the oral administration of pyroGlu-Leu (0.1 mg/kg body weight) attenuates dysbiosis in mice with experimental colitis. The objective of this study was to elucidate why such a low dose of pyroGlu-Leu attenuates dysbiosis in different animal models. High fat diet extensively increased the ratio of Firmicutes/Bacteroidetes in feces of rats compared to control diet. Oral administration of pyroGlu-Leu (1 mg/kg body weight) significantly attenuated high fat diet-induced dysbiosis. By focusing on the production of intestinal antimicrobial peptides, we found that pyroGlu-Leu significantly increased the level of 4962 Da peptides, which identified as the propeptide of rattusin or defensin alpha 9, in ileum. We also observed increased tryptic fragment peptides from rattusin in the lumen. Here, we report that orally administered pyroGlu-Leu attenuates dysbiosis by increasing in the host antimicrobial peptide, rattusin.

Quantitation and sensory properties of three newly identified pyroglutamyl oligopeptides in sake

Three new peptides: (pGlu)L-ethyl, (pGlu)LFGP-ethyl and (pGlu)LFNP-ethyl, were identified in the search for pyroglutamyl oligopeptide ethyl esters in sake. The ethyl esterified peptides in sake were quantitated using stable isotope dilution analysis and additional quantitation of (pGlu)L was performed using an external standard method. The concentrations of (pGlu)L-ethyl and (pGlu)L in 33 commercial sake samples ranged from 0.16 to 1.57 mg/L and 1.49 to 7.55 mg/L, respectively. The sensory properties of the pyroglutamyl oligopeptide ethyl esters and corresponding non-esterified peptides were examined: the estimated difference threshold of (pGlu)L (2.0 mg/L) and (pGlu)L-ethyl (0.267 mg/L) was exceeded in 32 and 26 samples, respectively. Estimated thresholds of (pGlu)LFGP-ethyl and (pGlu)LFNP-ethyl were often lower than the levels in quantitated sake samples. The sensory effects of these pyroglutamyl dipeptides on a model sake quality may be negative because of their unpleasant taste, however, (pGlu)LFNP-ethyl may be positive because of its mild taste.

Metabolite profiling of the fermentation process of "yamahai-ginjo-shikomi" Japanese sake

Sake is a traditional Japanese alcoholic beverage prepared by multiple parallel fermentation of rice. The fermentation process of "yamahai-ginjo-shikomi" sake is mainly performed by three microbes, Aspergillus oryzae, Saccharomyces cerevisiae, and Lactobacilli; the levels of various metabolites fluctuate during the fermentation of sake. For evaluation of the fermentation process, we monitored the concentration of moderate-sized molecules (m/z: 200-1000) dynamically changed during the fermentation process of "yamahai-ginjo-shikomi" Japanese sake. This analysis revealed that six compounds were the main factors with characteristic differences in the fermentation process. Among the six compounds, four were leucine- or isoleucine-containing peptides and the remaining two were predicted to be small molecules. Quantification of these compounds revealed that their quantities changed during the month of fermentation process. Our metabolomic approach revealed the dynamic changes observed in moderate-sized molecules during the fermentation process of sake, and the factors found in this analysis will be candidate molecules that indicate the progress of "yamahai-ginjo-shikomi" sake fermentation.