Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

Nano-Drug Delivery Systems Based on Natural Products

Natural products have proven to have significant curative effects and are increasingly considered as potential candidates for clinical prevention, diagnosis, and treatment. Compared with synthetic drugs, natural products not only have diverse structures but also exhibit a range of biological activities against different disease states and molecular targets, making them attractive for development in the field of medicine. Despite advancements in the use of natural products for clinical purposes, there remain obstacles that hinder their full potential. These challenges include issues such as limited solubility and stability when administered orally, as well as short durations of effectiveness. To address these concerns, nano-drug delivery systems have emerged as a promising solution to overcome the barriers faced in the clinical application of natural products. These systems offer notable advantages, such as a large specific surface area, enhanced targeting capabilities, and the ability to achieve sustained and controlled release. Extensive in vitro and in vivo studies have provided further evidence supporting the efficacy and safety of nanoparticle-based systems in delivering natural products in preclinical disease models. This review describes the limitations of natural product applications and the current status of natural products combined with nanotechnology. The latest advances in nano-drug delivery systems for delivery of natural products are considered from three aspects: connecting targeting warheads, self-assembly, and co-delivery. Finally, the challenges faced in the clinical translation of nano-drugs are discussed.

Ethyl Acetate Fractions of Tectona Grandis Crude Extract Modulate Glucose Absorption and Uptake as Well as Antihyperglycemic Potential in Fructose-Streptozotocin-Induced Diabetic Rats

Type 2 diabetes (T2D) is a global health challenge with increased morbidity and mortality rates yearly. Herbal medicine has provided an alternative approach to treating T2D with limited access to formal healthcare. Tectona grandis is being used traditionally in the treatment of diabetes. The present study investigated the antidiabetic potential of T. grandis leaves in different solvent extractions, and the crude extract that demonstrated the best activity was further fractionated through solvent-solvent partitioning. The ethyl acetate fraction of the ethanol crude extract showed the best antidiabetic activity in inhibiting α-glucosidase, delaying glucose absorption at the small intestine's lumen, and enhancing the muscle's postprandial glucose uptake. The ethyl acetate fraction was further elucidated for its ability to reduce hyperglycemia in diabetic rats. The ethyl acetate fraction significantly reduced high blood glucose levels in diabetic rats with concomitant modulation in stimulated insulin secretions through improved pancreatic β-cell function, insulin sensitivity by increasing liver glycogen content, and reduced elevated levels of liver glucose-6-phosphatase activity. These activities could be attributed to the phytochemical constituents of the plant.

Modulation Effects of Sargassum pallidum Extract on Hyperglycemia and Hyperlipidemia in Type 2 Diabetic Mice

The aim of this study was to investigate the antidiabetic effect of the extract from Sargassum pallidum (SPPE) on type 2 diabetes mellitus (T2DM) mice. SPPE treatment alleviated hyperglycemia, insulin resistance (IR), liver and pancreatic tissue damage, hyperlipidemia and hepatic oxidative stress resulting from T2DM. SPPE reversed phosphoenolpyruvate carboxylase (PEPCK) and hexokinase (HK) activities to improve gluconeogenesis and glycogen storage in the liver. Furthermore, SPPE modulated glucose metabolism by regulating the levels of mRNA expression involving the PI3K/Akt/FOXO1/G6pase/GLUT2 pathway and could inhibit fatty acid synthesis by reducing the gene expression levels of fatty acid synthase (FAS) and acetyl-CoA carboxylase-1 (ACC-1). A 16 sRNA analysis indicated that SPPE treatment also reversed gut dysbiosis by increasing the abundance of beneficial bacteria (Bacteroides and Lactobacillus) and suppressing the proliferation of harmful bacteria (Enterococcus and Helicobacter). Untargeted metabolomics results indicated that histidine metabolism, nicotinate and nicotinamide metabolism and fatty acid biosynthesis were significantly influenced by SPPE. Thus, SPPE may be applied as an effective dietary supplement or drug in the management of T2DM.

Polyphenols from whole millet grain (Setaria italica) alleviate glucose and lipid homeostasis in diet-induced obese mice by increasing endogenous GLP-1

BACKGROUND

Foxtail millet (Setaria italica) is a whole millet grain that has been considered for improving the disorder of glucose and lipid metabolism. The purpose of the work is to explore the extraction and enrichment of polyphenols from foxtail millets which can regulate the disorder of glucose and lipid metabolism by increasing endogenous GLP-1 (glucagon-like peptide-1).

RESULTS

The optimum ultrasound-assisted extraction (UAE) of foxtail millet polyphenols (FMPs) was as follows: 70 °C and 400 W and 70% ethanol concentration, further purification using macroporous resin. In vitro, the FMP eluent of 60% ethanol (FMP-60) has the best effect in promoting GLP-1 secretion from L cells among the different active components of FMP. Millet polyphenols (MPs) were obtained from finishing foxtail millet with the bran removed by the same extraction and purification method. Compared with MP-60, FMP-60 mainly included eight active phenolic constituents and contained more ferulic acid, p-coumaric acid, 2-hydroxycinnamic acid, and coniferaldehyde. After gavage treatment of diet-induced obese (DIO) mice with FMP-60, FMP-60 promoted endogenous GLP-1 secretion in mice and ameliorated disorders of glucolipid metabolism in DIO mice.

CONCLUSION

FMP-60 could improve glucose homeostasis and ameliorates metabolic disease by promoting the endogenous GLP-1 level and preventing weight gain in DIO mice. © 2023 Society of Chemical Industry.

In Silico and In Vitro Analyses to Repurpose Quercetin as a Human Pancreatic α-Amylase Inhibitor

Human pancreatic α-amylase (HPA), situated at the apex of the starch digestion hierarchy, is an attractive therapeutic approach to precisely regulate blood glucose levels, thereby efficiently managing diabetes. Polyphenols offer a natural and multifaceted approach to moderate postprandial sugar spikes, with their slight modulation in carbohydrate digestion and potential secondary benefits, such as antioxidant and anti-inflammatory effects. Taking into consideration the unfavorable side effects of currently available commercial medications, we aimed to study a library of polyphenols attributed to their remarkable antidiabetic properties and screened the most potent HPA inhibitor via a comprehensive in silico study encompassing molecular docking, molecular mechanics with generalized Born and surface area solvation (MM/GBSA) calculation, molecular dynamics (MD) simulation, density functional theory (DFT) study, and pharmacokinetic properties followed by an in vitro assay. Significant hydrogen bonding with the catalytic triad residues of HPA, prominent MM/GBSA binding energy of -27.03 kcal/mol, and the stable nature of the protein-ligand complex with regard to 100 ns MD simulation screened quercetin as the best HPA inhibitor. Additionally, quercetin showed strong reactivity in the substrate-binding pocket of HPA and exhibited favorable pharmacokinetic properties with a considerable inhibitory concentration (IC50) of 57.37 ± 0.9 μg/mL against α-amylase. This study holds prospects for HPA inhibition and suggests quercetin as an approach to therapy for diabetes; however, it is imperative to conduct further research.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.

Exploration of natural flavones' bioactivity and bioavailability in chronic inflammation induced-type-2 diabetes mellitus

Diabetes, being the most widespread illness, poses a serious threat to global public health. It seems that inflammation plays a critical role in the pathophysiology of diabetes. This review aims to demonstrate a probable link between type 2 diabetes mellitus (T2DM) and chronic inflammation during its development. Additionally, the current review examined the bioactivity of natural flavones and the possible molecular mechanisms by which they influence diabetes and inflammation. While natural flavones possess remarkable anti-diabetic and anti-inflammatory bioactivities, their therapeutic use is limited by the low oral bioavailability. Several factors contribute to the low bioavailability, including poor water solubility, food interaction, and unsatisfied metabolic behaviors, while the diseases (diabetes, inflammation, etc.) causing even less bioavailability. Throughout the years, different strategies have been developed to boost flavones' bioavailability, including structural alteration, biological transformation, and innovative drug delivery system design. This review addresses current advancements in improving the bioavailability of flavonoids in general, and flavones in particular. Clinical trials were also analyzed to provide insight into the potential application of flavonoids in diabetes and inflammatory therapies.

Impact of thermal processing on dietary flavonoids

Flavonoids are a class of polyphenols which are widely distributed in natural products and foods. They have diverse bioactivities, including anti-inflammatory, anti-aging, and antioxidant activities. Generally, the foods rich in flavonoids are usually consumed after thermal processing. However, thermal stability of flavonoids is usually low, and thermal processing could cause either positive or negative influences on their stability and bioactivities. In this review, the effects of thermal processing on thermal stability and bioactivity of dietary flavonoids from different food sources are summarized. Then, strategies to improve thermal stability of dietary flavonoids are discussed and the effect of some promising thermal technologies are also preliminary clarified. The promising thermal technologies may be alternative to conventional thermal processing technologies.

Regulatory mechanisms of the edible alga Ulva lactuca polysaccharide via modulation of gut microbiota in diabetic mice

In this study, Ulva lactuca polysaccharide (ULP) antihyperglycemic effect was assessed by monitoring changes in the gut microbiota of aging diabetic mice. The results showed that ULP alleviated type 2 diabetes by improving insulin tolerance, increasing SOD and CAT activities, and thus lowering blood glucose level. Moreover, ULP regulated the expressions of INSR and AMPK concurrent with inhibition the expression of JNK, JAK, STAT3, p16 and p38 to improve glucose metabolism dysfunction. Interestingly, the abundance of Alloprevotella and Pediococcus change might the key factor for ULP antihyperglycemic effectiveness in aging-related diabetes. These results suggest that ULP can exert a mechanism of blood glucose regulation by improving intestinal diversity composition asides from direct insulin mimetic actions.

The stability and degradation products of polyhydroxy flavonols in boiling water

Polyhydroxy flavonols readily degraded during thermal processing. In this study, the UPLC-Q-tof-MS/MS was applied to explore the stability of dietary polyhydroxy flavonols, myricetin, kaempferol, galangin, fisetin, myricitrin, quercitrin and rutin, in boiling water. The decomposition of flavonols was mainly caused by the heterocyclic ring C opening to form simpler aromatic compounds. The degradation products mainly included 1,3,5-benzenetriol, 3,4,5-trihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid and 2,4,6-trihydroxybenzaldehyde, etc. Compared with myricetin with a pyrogallol-type structure on the ring B, the glycoside in myricitrin slightly affects the stability. However, the glycosides in rutin and quercitrin dramatically improved the stability in water. During the boiling process, flavonols underwent a series of chemical reactions, such as hydroxylation, dehydroxylation, deglycosidation, deprotonation, and C-ring cleavage.

Sea bass protein-polyphenol complex stabilized high internal phase of algal oil Pickering emulsions to stabilize astaxanthin for 3D food printing

The protective effect of sea bass protein (SBP)-(-)-epigallocatechin-3-gallate (EGCG) covalent complex-stabilized high internal phase (algal oil) Pickering emulsions (HIPPEs) on astaxanthin and algal oils was demonstrated in this study. The SBP-EGCG complex with better wettability and antioxidant activity was formed by the free radical-induced reaction to stabilize HIPPEs. Our results show that the SBP-EGCG complex formed dense particle shells surrounding the oil droplets, and the shells were crosslinked with the complex in the continuous phase to produce a network structure. The rheological analysis demonstrated that the SBP-EGCG complex endowed HIPPEs with high viscoelasticity, high thixotropic recovery, and good thermal stability, which were beneficial for three-dimensional (3D) printing applications. HIPPEs stabilized by SBP-EGCG complex were applied to improve the stability and bioaccessibility of astaxanthin and to delay algal oil lipid oxidation. The HIPPEs might become a food-grade 3D printing material served as a delivery system for functional foods.

Health-Promoting Properties and Potential Application in the Food Industry of Citrus medica L. and Citrus × clementina Hort. Ex Tan. Essential Oils and Their Main Constituents

Citrus is an important genus in the Rutaceae family, with high medicinal and economic value, and includes important crops such as lemons, orange, grapefruits, limes, etc. The Citrus species is rich sources of carbohydrates, vitamins, dietary fibre, and phytochemicals, mainly including limonoids, flavonoids, terpenes, and carotenoids. Citrus essential oils (EOs) consist of several biologically active compounds mainly belonging to the monoterpenes and sesquiterpenes classes. These compounds have demonstrated several health-promoting properties such as antimicrobial, antioxidant, anti-inflammatory, and anti-cancer properties. Citrus EOs are obtained mainly from peels, but also from leaves and flowers, and are widely used as flavouring ingredients in food, cosmetics, and pharmaceutical products. This review focused on the composition and biological properties of the EOs of Citrus medica L. and Citrus clementina Hort. Ex Tan and their main constituents, limonene, γ-terpinene, myrcene, linalool, and sabinene. The potential applications in the food industry have been also described. All the articles available in English or with an abstract in English were extracted from different databases such as PubMed, SciFinder, Google Scholar, Web of Science, Scopus, and Science Direct.

Recent advances in the biosynthesis, bioavailability, toxicology, pharmacology, and controlled release of citrus neohesperidin

Neohesperidin (hesperetin 7-O-neohesperidoside), a well-known flavanone glycoside widely found in citrus fruits, exhibits a variety of biological activities, with potential applications ranging from food ingredients to therapeutics. The purpose of this manuscript is to provide a comprehensive overview of the chemical, biosynthesis, and pharmacokinetics profiles of neohesperidin, as well as the therapeutic effects and mechanisms of neohesperidin against potential diseases. This literature review covers a wide range of pharmacological responses elicited by Neohesperidin, including neuroprotective, anti-inflammatory, antidiabetic, antimicrobial, and anticancer activities, with a focus on the mechanisms of those pharmacological responses. Additionally, the mechanistic pathways underlying the compound's osteoporosis, antiulcer, cardioprotective, and hepatoprotective effects have been outlined. This review includes detailed illustrations of the biosynthesis, biopharmacokinetics, toxicology, and controlled release of neohesperidine. Neohesperidin demonstrated a broad range of therapeutic and biological activities in the treatment of a variety of complex disorders, including neurodegenerative, hepato-cardiac, cancer, diabetes, obesity, infectious, allergic, and inflammatory diseases. Neohesperidin is a promising therapeutic candidate for the management of various etiologically complex diseases. However, further in vivo and in vitro studies on mechanistic potential are required before clinical trials to confirm the safety, bioavailability, and toxicity profiles of neohesperidin.

Kaempferol and atherosclerosis: From mechanism to medicine

Natural products possess pleiotropic cardiovascular protective effects owing to their anti-oxidation, anti-inflammation and anti-thrombotic properties. Kaempferol, (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), is a kind of naturally occurring flavonoid existing in many common fruits and vegetables (e.g., onions, broccoli, strawberries and grapes) and particularly in traditional Chinese medicine as exemplified by Ginkgo biloba. Epidemiological, preclinical and clinical studies have revealed an inverse association between the consumption of kaempferol-containing foods and medicines and the risk of developing cardiovascular diseases. Numerous translational studies in experimental animal models and cultured cells have demonstrated a wide range of pharmacological activities of kaempferol. In this article, we reviewed the antioxidant, anti-inflammatory and cardio-protective activities of kaempferol and elucidated the potential molecular basis of the therapeutic capacity of kaempferol by focusing on its anti-atherosclerotic effects. Overall, the review presents the health benefits of kaempferol-containing plants and medicines and reflects on the potential of kaempferol as a possible drug candidate to prevent and treat atherosclerosis, the underlying pathology of most cardiovascular diseases.

Modulation of integrin receptor by polyphenols: Downstream Nrf2-Keap1/ARE and associated cross-talk mediators in cardiovascular diseases

As a group of heterodimeric and transmembrane glycoproteins, integrin receptors are widely expressed in various cell types overall the body. During cardiovascular dysfunction, integrin receptors apply inhibitory effects on the antioxidative pathways, including nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch like ECH Associated Protein 1 (Keap1)/antioxidant response element (ARE) and interconnected mediators. As such, dysregulation in integrin signaling pathways influences several aspects of cardiovascular diseases (CVDs) such as heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. So, modulation of integrin pathway could trigger the downstream antioxidant pathways toward cardioprotection. Regarding the involvement of multiple aforementioned mediators in the pathogenesis of CVDs, as well as the side effects of conventional drugs, seeking for novel alternative drugs is of great importance. Accordingly, the plant kingdom could pave the road in the treatment of CVDs. Of natural entities, polyphenols are multi-target and accessible phytochemicals with promising potency and low levels of toxicity. The present study aims at providing the cardioprotective roles of integrin receptors and downstream antioxidant pathways in heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. The potential role of polyphenols has been also revealed in targeting the aforementioned dysregulated signaling mediators in those CVDs.

Investigation of new products of quercetin formed in boiling water via UPLC-Q-TOF-MS-MS analysis

Quercetin is one of most important flavonoids in foods with multi-benefits for human health. The thermal processing is the main food processing approach. Here, the stability of quercetin in boiling water (100 °C) was investigated by UPLC-Q-TOF-MS-MS. With the increasing boiling time, quercetin gradually degraded, and the initial degradation time is 17.57 min and the half-degradation time is 169.72 min. The degradation mechanisms included oxidation, hydroxylation and nucleophilic attack cleavage. Combining the retention time and characteristic fragment ion information of the corresponding standards, the degraded products of quercetin in boiling water were identified as 3,4-dihydroxyphenylglyoxylate, 1,3,5-trihydroxybenzene, 3,4,5-trihydroxybenzoic acid and 2,4,6-trihydroxybenzoic acid. Moreover, 2,3-dihydro-2,3',4',5,7-pentahydroxy-3-oxoflavone, quercetin dimers and quinones were also formed.

Recent advances in biological properties of brown algae-derived compounds for nutraceutical applications

The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.

Formation and metabolism of 6-(1-acetol)-8-(1-acetol)-rutin in foods and in vivo, and their cytotoxicity

Methylglyoxal (MGO) is a highly reactive precursor which forms advanced glycation end-products (AGEs) in vivo, which lead to metabolic syndrome and chronic diseases. It is also a precursor of various carcinogens, including acrylamide and methylimidazole, in thermally processed foods. Rutin could efficiently scavenge MGO by the formation of various adducts. However, the metabolism and safety concerns of the derived adducts were paid less attention to. In this study, the optical isomers of di-MGO adducts of rutin, namely 6-(1-acetol)-8-(1-acetol)-rutin, were identified in foods and in vivo. After oral administration of rutin (100 mg/kg BW), these compounds reached the maximum level of 15.80 μg/L in plasma at 15 min, and decreased sharply under the quantitative level in 30 min. They were detected only in trace levels in kidney and fecal samples, while their corresponding oxidized adducts with dione structures presented as the predominant adducts in kidney, heart, and brain tissues, as well as in urine and feces. These results indicated that the unoxidized rutin-MGO adducts formed immediately after rutin ingestion might easily underwent oxidation, and finally deposited in tissues and excreted from the body in the oxidized forms. The formation of 6-(1-acetol)-8-(1-acetol)-rutin significantly mitigated the cytotoxicity of MGO against human gastric epithelial (GES-1), human colon carcinoma (Caco-2), and human umbilical vein endothelial (HUVEC) cells, which indicated that rutin has the potential to be applied as a safe and effective MGO scavenger and detoxifier, and AGEs inhibitor.

Ameliorating Effect on Glycolipid Metabolism of Spirulina Functional Formulation Combination from Traditional Chinese Medicine

Insulin resistance is the major factor involved in the pathogenesis of type 2 diabetes. Although the oral drug metformin (MH) is widely used to reduce hyperglycemia, it is associated with adverse effects. Therefore, there is an urgent need to search for safe and natural foods that do not cause adverse effects as alternatives to commercial drugs. In this study, the active substances from Spirulina platensis, Grifola frondosa, Panax ginseng, and chromium-rich yeast were used to obtain Spirulina functional formulations (SFFs), and its therapeutic effects on mice with glycolipid metabolism disorder (GLD) were investigated. Results showed that SFFs not only improved glycolipid metabolism and reduced inflammation in mice with GLD but also showed good regenerative effects on the liver, jejunum, and cecum tissues. Moreover, SFFs could inhibit the growth of harmful microbes in the intestine and promote the proliferation of beneficial bacteria, thereby promoting the production of short-chain fatty acids and further regulating GLD. Additionally, SFFs significantly increased the expression of INS, INSR, IRS-1, PI3K, AKT-1, and GLUT-4 genes and significantly decreased that of GSK-3β in the INS/PI3K/GLUT-4 signaling pathway. Therefore, the findings of this study suggest that SFFs can be further developed as a new class of therapeutic agents against GLD.

Screening of potent α-glucosidase inhibitory and antioxidant polyphenols in Prunella vulgaris L. by bioreaction-HPLC-quadrupole-time-of-flight-MS/MS and in silico analysis

Prunella vulgaris L. is a well-known traditional Chinese medicine for blood glucose homeostasis and antioxidant potential. Ethyl acetate fraction of P. vulgaris L. demonstrated higher phenolic content (85.53 ± 6.74 mg gallic acid equivalents per gram dry weight), α-glucosidase inhibitory (IC₅₀ , 69.13 ± 2.86 μg/mL), and antioxidant (IC₅₀ , 8.68 ± 1.01 μg/mL) activities. However, the bioactive polyphenols responsible for the beneficial properties remain unclear. Here, bioreaction-HPLC-quadrupole-time-of-flight-MS/MS method was developed for rapid, accurate, and efficient screening and identification of polyphenols with α-glucosidase inhibitory and antioxidant activities from P. vulgaris L. Bioactive polyphenols can specifically bind with α-glucosidase or react with 1,1-diphenyl-2-picryl-hydrazyl radical, which was easily discriminated from nonactive compounds. Subsequently, twenty bioactive polyphenols (sixteen phenyl propionic acid derivatives and four flavonoids) were screened and identified. Furthermore, molecular docking analysis revealed that screened twenty polyphenols bind with the active sites of α-glucosidase through hydrogen bonding and π-π stacking. Density functional theory calculations demonstrated their electron transport ability and chemical reactivity. The in silico analysis confirmed the screened results. In summary, this study provided a valuable strategy for rapid discovering bioactive compounds from complex natural products, and offered scientific evidence for further development and application of P. vulgaris L. This article is protected by copyright. All rights reserved.

Nutraceutical Eriocitrin (Eriomin) Reduces Hyperglycemia by Increasing Glucagon-Like Peptide 1 and Downregulates Systemic Inflammation: A Crossover-Randomized Clinical Trial

This double-blind, randomized, placebo/controlled, crossover study evaluated the efficacy of Eriomin^® in reducing hyperglycemia and improving diabetes-related biomarkers in individuals with hyperglycemia above 110 mg/dL (mean 123 ± 18 mg/dL). Subjects (n = 30), divided into two groups (Eriomin or Placebo), who received a dose of 200 mg/d of the designated supplement for 12 weeks and, after a washout period of 2 weeks, switched to the other supplement in the following 12 weeks. Assessments of biochemical, metabolic, inflammatory, blood pressure, anthropometry, and dietary parameters were performed at the beginning and end of each intervention. Treatment with 200 mg/d of Eriomin significantly decreased blood glucose (-5%), homeostasis model assessment of insulin resistance (-11%), glucagon (-13%), interleukin-6 (-14%), tumor necrosis factor alpha (-20%), and alkaline phosphatase (-13%); but increased glucagon-like peptide 1 (GLP-1) by (17%) (P ≤ .05). At the end of the placebo period, there was a 13% increase in triglycerides (P ≤ .05). Other parameters evaluated did not change with Eriomin or placebo. In conclusion, intervention with Eriomin benefited the glycemic control of prediabetic and diabetic patients, with higher blood glucose levels, by increasing GLP-1 and decreasing systemic inflammation.

Metabolomics and biochemical insights on the regulation of aging-related diabetes by a low-molecular-weight polysaccharide from green microalga Chlorella pyrenoidosa

•

C. pyrenoidosa polysaccharide (CPP) have hypoglycemic activity and oxidation resistance.

•

CPP prevents oxidative stress and stimulates insulin via affecting phenylpyruvic acid.

•

CPP can regulate the GLP-1R/IL-6R and ZO-1/MMP-2 pathways.

•

CPP activated BCL-6 to promote cell survival in brain.

Globally, aging and diabetes are considered prevalent threats to human health. Chlorella pyrenoidosa polysaccharide (CPP) is a natural active ingredient with multiple health benefits including antioxidant and hypolipidemic activities. In this study, the aging-related diabetic (AD) mice model was established to investigate the underlying hypoglycemic and antioxidant mechanisms of CPP. It improved superoxide dismutase, catalase (CAT), glutathione peroxidase (GSH-px), and malondialdehyde activities in liver and insulin secretion. CAT and GSH-px activity in the brain increased after CPP administration. In addition, through histopathological examinations, it was evident that injuries in the liver, brain, jejunum, and pancreas were restored by CPP. This restoration was likely mediated via the activation of glucagon-like peptide-1 receptor/FOXO-1 (forkhead box O1) pathway concurrent with the inhibition of interleukin-6 receptor/FOXO-1 pathway. Furthermore, metabolomics and correlation analysis revealed that CPP possibly relived AD through changes in insulin levels and declined oxidative stress as regulated by phenylpyruvic acid. These findings suggested that CPP exerted antioxidant and hypoglycemic roles in an AD mice model, thereby providing a sound scientific foundation for further development and utilization of CPP.

Hypoglycaemic and anti-ageing activities of green alga Ulva lactuca polysaccharide via gut microbiota in ageing-associated diabetic mice

Ageing-related type 2 diabetes is a significant public health problem. Particularly, the number of cases and fatality rates of ageing-associated diabetes increase with population ageing. This study aimed to investigate the structural characterisation of Ulva lactuca polysaccharide (ULP) and the hypoglycaemic effect on ageing-associated diabetic mice using gut microbiota variation. Sugar residuals analysis showed that the purified ULP (ULP-1) comprised β-D-Xylp-(1→3)-β-D-Arap-(1→6)-β-D-Galp-(1→6)-β-D-Glcp linked to [→α-L-Rhap-(1→4)-β-D-GlcpA→]_n and α-D-Manp-(1→4)-α-L-Rhap(2SO₃^-)-(1→2)-α-L-Rhap(4SO₃^-)-(1→2)-α-L-Arap-(1→2)-α-L-Rhap-(1→ as its side chains at β-D-Glcp. Moreover, ULP modulated the expression levels of p16^Ink4a, MMP2, FoxO1, GLP-1/GLP-1R, STAT3, and GLUT4 to improve the status of ageing and diabetes, which was concurrent with the increased abundance of Dubosiella, Enterococcus, Romboutsia, Bifidobacterium, Kurthia, Clostridium_sensu_stricto_1, Corynebacterium, Faecalibaculum, Aerococcus and Vibrio. Notably, Dubosiella, Romboutsia, Bifidobacterium, Turicibacter and Clostridium_sensu_stricto_1 could serve as important intermediates for delaying ageing and diabetes. Additionally, the ULP-1 structure is strongly binding interaction with the target protein through hydrogen bonding and Van der Waals force, especially for GLP-1 (-10.34 kcal/mol), p16^Ink4a (-10.51 kcal/mol) and GLP-1R (-8.57 kcal/mol). Moreover, the average length of the hydrogen bond was observed to be 2.36 MPa, which is smaller than that of the traditional hydrogen bond. Therefore, ULP has the potential to function as a nutraceutical to delay or prevent the development of ageing-related type 2 diabetes.

Regulatory mechanisms of the green alga Ulva lactuca oligosaccharide via the metabolomics and gut microbiome in diabetic mice

Type 2 diabetes (T2D) has emerged as one of the most acute public health diseases of the present time, which increases with the population ageing. This study aimed to evaluate the hypoglycaemic activity of Ulva lactuca oligosaccharide (ULO) under ageing-related diabetes conditions in an animal model. The results demonstrated that ULO can promote hypoglycaemia and delay senescence as mediated via GLP-1/GLP-1R pathway to mobilize the intercommunication between the brain and gut. In addition, twenty-six different metabolites and eight different bacteria were screened in the brain and the gut, respectively. A network relationship displayed that all-trans-retinoic acid has positive relationships with Bifidobacterium and Streptococcus, suggesting that plays a potential key role in maintaining the hypoglycaemic and anti-ageing activities of ULO. Based on these findings, ULO might be an efficient therapy for restoring blood glucose metabolism and delaying brain senescence in elderly T2D patients.

•

U. lactuca oligosaccharide (ULO) acts as a GLP-1/GLP-1R agonist to control circulating glucose.

•

ULO significantly reduces the expression of brain aging factor p16^Ink4a.

•

All-trans-Retinoic acid and Streptococcus are the key mediators of hypoglycemia.

Anti-inflammatory activity of flavonols via inhibiting MAPK and NF-κB signaling pathways in RAW264.7 macrophages

Fisetin (Fis), quercetin (Que), and myricetin (Myr) are flavonols with similar structure but different number of hydroxyl groups. The present research focused on the anti-inflammatory effect of these three flavonols in lipopolysaccharide-stimulated RAW264.7 cells. The number and site of hydroxyl group in flavonols obviously affected their anti-inflammation activity. These flavonols suppressed the overproduction of nitric oxide. Fis showed the best activity with an inhibition rate of 52% at 20 μM. Moreover, the flavonols reduced the levels of ROS, TNF-α, and IL-6. The mechanistic study showed that they inhibited the activation of NF-κB and MAPK pathways by suppressing the phosphorylation of IκBα, p65, JNK, ERK, p38, MEK, and reducing the nuclear translocation of NF-κB p65. In addition, the metabolism of the flavonols was examined. The results indicated that Fis was both methylated and glucuronidated. Que and Myr were mainly transformed into methylated products. This study highlights the anti-inflammatory activity of flavonols, particularly Fis, which has the potential for the prevention or treatment of inflammation as an adjuvant medicine or food additive.

•

Flavonols suppressed the production of NO and ROS.

•

Flavonols partially blocked the activation of NF-κB and MAPK pathways.

•

Fisetin is an excellent anti-inflammatory reagent.

•

The number of hydroxyl group in flavonols obviously affects their anti-inflammation activity.

Black raspberries attenuate colonic adenoma development in Apc Min mice: Relationship to hypomethylation of promoters and gene bodies

Recent studies have suggested that in addition to promoter region, DNA methylation in intragenic and intergenic regions also changes during physiological processes and disease. The current study showed that feeding of black raspberries (BRBs) to Apc^Min mice suppressed colon and intestinal tumors. MBDCap-seq suggested that dietary BRBs hypomethylated promoter, intragenic, and intergenic regions. Annotation of those regions highlighted genes in pathways involved in immune regulation, inflammatory signaling, production of nitric oxide and reactive oxygen species, and progression of colorectal cancer. BRB phytochemicals (e.g., ellagic acid, anthocyanins, oligosaccharides) and their gut bacterial metabolites (e.g., urolithin, protocatechuic acid, short-chain fatty acids) inhibited DNMT1 and DNMT3B activities in a cell-free assay. Our results suggest that BRBs’ hypomethylating activities result from the combined effects of multiple BRB phytochemicals and their gut bacterial metabolites. Because similar substances are found in many plant products, our results with BRBs might also apply to commonly consumed fruits and vegetables.

Plant Bioactive Peptides: Current Status and Prospects Towards Use on Human Health

Large numbers of bioactive peptides with potential applications in protecting against human diseases have been identified from plant sources. In this review, we summarized recent progress in the research of plant-derived bioactive peptides, encompassing their production, biological effects, and mechanisms. This review focuses on antioxidant, antimicrobial, antidiabetic, and anticancer peptides, giving special attention to evidence derived from cellular and animal models. Studies investigating peptides with known sequences and well-characterized peptidic fractions or protein hydrolysates will be discussed. The use of molecular docking tools to elucidate inter-molecular interactions between bioactive peptides and target proteins is highlighted. In conclusion, the accumulating evidence from in silico, in vitro and in vivo studies to date supports the envisioned applications of plant peptides as natural antioxidants as well as health-promoting agents. Notwithstanding, much work is still required before the envisioned applications of plant peptides can be realized. To this end, future researches for addressing current gaps were proposed.

Polyphenol-rich extract of Zhenjiang aromatic vinegar ameliorates high glucose-induced insulin resistance by regulating JNK-IRS-1 and PI3K/Akt signaling pathways

Zhenjiang aromatic vinegar is a famous traditional fermented cooking ingredient in China, with multiple nutritional and medicinal applications. Zhenjiang aromatic vinegar extract (100-400 μg/mL) is rich in polyphenols increased the glucose uptake and glucose consumption in high glucose-induced insulin resistant HepG2 (IR-HepG2) cells. Zhenjiang aromatic vinegar extract enhanced glycogen synthesis and attenuated gluconeogenesis by regulating key enzymes in IR-HepG2 cells. In addition, Zhenjiang aromatic vinegar extract ameliorated high glucose-induced IR by inhibiting phosphorylated insulin receptor substrate-1 (IRS-1) expression and activating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in IR-HepG2 cells. Moreover, Zhenjiang aromatic vinegar extract reduced reactive oxygen species generation and phosphorylated c-Jun NH₂ terminal kinase (JNK) expression in IR-HepG2 cells. The attenuation of the high glucose is owned to the PI3K/Akt pathway activation, glycogen synthesis induction and gluconeogenesis suppression in IR-HepG2 cells.