Rice-memolin, a novel peptide derived from rice bran, improves cognitive function after oral administration in mice

Medium-chain triglycerides tricaprin TC10 and tricaprylin TC8 attenuated HFD-induced cognitive decline in a manner dependent on or independent of GLP-1

Population aging is the most important social and medical demographic issue worldwide; therefore, healthy aging is important. The increasing prevalence of dementia and cognitive decline are major health concerns. Medium-chain triglycerides (MCTs) have been shown to improve cognitive decline. The present study investigated the effects and mechanisms of action of orally administered MCTs, including tricaprylin (TC8), tricaprin (TC10), and trilaurin (TC12), on cognitive function in mice fed a high-fat diet (HFD). The administration of TC8 and TC10 attenuated cognitive decline. A relationship has been reported between cognitive dysfunction and impaired glucose metabolism. The administration of TC8 and TC10 also reduced blood glucose levels in the glucose tolerance test. Cognitive improvements by MCTs are widely attributed to the ketogenic effect. In the present study, TC8 significantly increased blood ketone concentrations, whereas TC10 did not. On the other hand, TC10 increased the plasma concentration of glucagon-like peptide-1 (GLP-1), the hormone that promotes insulin secretion. The administration of the GLP-1 receptor antagonist, exendin(9-39), blocked the cognitive-enhancing effects of TC10. These results suggest that TC10 improved cognitive function via the GLP-1 receptor. The in vitro experiment indicated that 2-monocaprin (2-MC10), not TC10, stimulated the secretion of GLP-1 and decreased intracellular cAMP concentrations. In conclusion, we herein demonstrated that TC8 and TC10 attenuated cognitive decline through different mechanisms. This is the first study to suggest that TC10 attenuates cognitive decline via GLP-1.

Anti-obesity peptides from food: Production, evaluation, sources, and commercialization

The global obesity epidemic has heightened interest in natural solutions, with anti-obesity peptides emerging as promising candidates. Derived from food sources such as plants, algae, marine organisms, and products like milk and eggs, these peptides combat obesity through various mechanisms but face challenges in production and scalability. The aim of this review is to explore their sources, mechanisms, measurement, and synthesis methods, including innovative approaches such as de novo synthesis, proteomics, and bioinformatics. Its unique contribution lies in critically analyzing the current state of research while highlighting novel synthesis techniques and their practical relevance in addressing commercialization challenges, offering valuable insights for advancing anti-obesity peptide development. Diverse methods for assessing the anti-obesity properties of these peptides are discussed, encompassing both in vitro and in vivo experimental approaches, as well as emerging alternatives. The review also explores the integration of cutting-edge technologies in peptide synthesis with the potential to revolutionize scalability and cost-effectiveness. Key findings assert that despite the great potential of peptides from various food sources to fight against obesity and advances in their identification and analysis, challenges like scalability, regulatory hurdles, bioavailability issues, high production costs, and consumer appeal persist. Future research should explore the use of bioinformatics tools and advanced peptide screening technologies to identify and design peptides with enhanced efficacy and bioavailability, efficient and cost-effective extraction and purification methods, sustainable practices such as utilizing byproducts from the food industry, and the efficacy of products containing isolated anti-obesity peptides versus whole materials in clinical settings.

Fatty acid amides present in Camembert cheese improved cognitive decline after oral administration in mice

Herein, we investigated the effects of Camembert cheese (CC) and its fatty acid contents on cognitive function in mice by employing the object recognition test to evaluate hippocampus-dependent memory. Orally administered CC improved the cognitive decline induced by a high-fat diet. Next, we focused on myristamide (MA), oleamide, and stearamide, which are fatty acid amides produced during the fermentation process of CC. We found that oral administration of MA improved cognitive decline. Notably, an improvement was not observed using myristic acid, a free fatty acid that is not amidated. Thus, fatty acid amidation may contribute to the physiological activity. Moreover, we investigated changes in gene expression related to neurogenesis in the hippocampus. After MA administration, mRNA expression analysis indicated that MA increased hippocampal brain-derived neurotrophic factor expression.

Ovomemolins: Egg-derived peptides that improved cognitive decline after oral administration in mice

Eggs not only contain all the molecules necessary to nurture new life but are also rich in nutrients such as high-quality protein. For example, epidemiologic studies have shown that egg intake is positively correlated with cognitive function. Thus, we specifically examined the effect of ovalbumin, a major protein present in egg whites, on cognitive function. First, we found that an orally administered enzymatic digest of ovalbumin improves cognitive function in mice fed a high-fat diet. Then, we narrowed down candidate peptides based on the prediction of peptide production according to enzyme-substrate specificity and comprehensive peptide analysis of the digest. We found that three peptides, namely ILPEY, LYRGGLEP, and ILELP, improve cognitive function after oral administration. We also showed that ILPEY, LYRGGLEP, and ILELP were present in the digest and named them ovomemolins A (OMA), B, and C, respectively. Notably, ovomemolins are the first peptides derived from egg whites that have been shown to improve cognitive function. The cognitive improvement induced by OMA, the most abundant of the peptides in the digest, was inhibited by methyllycaconitine, an antagonist of α7nAChR, which is known to be related to memory. These results suggest that OMA improves cognitive function through the acetylcholine system. After OMA administration, brain-derived neurotrophic factor (BDNF) mRNA expression and the number of 5-bromo-2'-deoxyuridine-positive cells suggested that OMA increases hippocampal BDNF expression and neurogenesis.

Human milk-specific fat components enhance the secretion of ghrelin by MGN3-1 cells

Triacylglycerols (TAGs) are a major fat component in human milk. Since gastric lipase produces 1,2-diacylglycerol from TAGs, we focused on the bioactivity of human milk-derived diacylglycerols in stomach cells. Ghrelin is produced in the stomach and acts as an important regulator of growth hormone secretion and energy homeostasis. In this study, we showed that 1-oleoyl-2-palmitoylglycerol (OP) increased ghrelin secretion, whereas 1,3-dioleoyl-2-palmitoylglycerol (OPO), a major component of human milk TAGs, did not increase ghrelin secretion in the ghrelin-secreting cell line, MGN3-1. Therefore, diacylglycerol OP may directly contribute to the regulation of ghrelin secretion. We also found that 2-palmitoylglycerol and 1- and 2-oleoylglycerol increased ghrelin secretion. Finally, we demonstrated that intracellular cAMP levels and preproghrelin and ghrelin O-acyl transferase expression levels were enhanced by OP treatment in MGN3-1 cells. This may represent an example of a novel mother-infant interaction mediated by fat components derived from human breast milk.