Antidiabetic plant-derived nutraceuticals: a critical review. Eur J Nutr. 2018;57:1275-1299. [PMID: 29022103 DOI: 10.1007/s00394-017-1552-6]

Potential Role of Phytochemicals as Glucagon-like Peptide 1 Receptor (GLP-1R) Agonists in the Treatment of Diabetes Mellitus

Currently, there is no known cure for diabetes. Different pharmaceutical therapies have been approved for the management of type 2 diabetes mellitus (T2DM), some are in clinical trials and they have been classified according to their route or mechanism of action. Insulin types, sulfonylureas, biguanides, alpha-glucosidase inhibitors, thiazolidinediones, meglitinides, sodium-glucose cotransporter type 2 inhibitors, and incretin-dependent therapies (glucagon-like peptide-1 receptor agonists: GLP-1R, and dipeptidyl peptidase 4 inhibitors: DPP-4). Although some of the currently available drugs are effective in the management of T2DM, the side effects resulting from prolonged use of these drugs remain a serious challenge. GLP-1R agonists are currently the preferred medications to include when oral metformin alone is insufficient to manage T2DM. Medicinal plants now play prominent roles in the management of various diseases globally because they are readily available and affordable as well as having limited and transient side effects. Recently, studies have reported the ability of phytochemicals to activate glucagon-like peptide-1 receptor (GLP-1R), acting as an agonist just like the GLP-1R agonist with beneficial effects in the management of T2DM. Consequently, we propose that careful exploration of phytochemicals for the development of novel therapeutic candidates as GLP-1R agonists will be a welcome breakthrough in the management of T2DM and the co-morbidities associated with T2DM.

Hypoglycemic Effects of Extracts Obtained from Endemic Betonica bulgarica Degen and Neič

The increasing prevalence of diabetes mellitus, together with the limited access of many patients to conventional antidiabetic drugs and the side effects resulting from their use, are the reason for the ever-increasing need for new agents. One of the most important strategies used in the therapy of this disease is to reduce the postprandial blood glucose level by inhibiting the carbohydrate-degrading enzymes α-amylase and α-glucosidase. The purpose of the present study was to provide in vitro evidence for the potential hypoglycemic effect of leaf and inflorescence aqueous extracts of Bulgarian endemic species Betonica bulgarica Degen and Neič. Total phenolic and flavonoid contents and antioxidant activities were determined by spectrophotometric methods. Qualitative and quantitative determinations of principal phenolic acids and flavonoids were performed using HPLC with a dual absorbance detector. The plant extracts were able to retard the enzymatic breakdown of starch to glucose with 50% inhibiting concentrations of 1.86 mg/mL and 1.54 mg/mL respectively for leaf and flower extract. Some of the plant constituents are proven inhibitors of α-amylase and/or α-glucosidase, but their adsorption on starch seems to be one additional mechanism for the inhibition of glucose release. Combination index analysis carried out with binary mixtures of acarbose and plant extracts showed a tendency toward synergism with an increase in concentrations and level of inhibition.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Gelatine nanoparticles encapsulating three edible plant extracts as potential nanonutraceutical agents against type 2 diabetes mellitus

AIM

To optimise, and characterise gelatine nanoparticles (GNPs) encapsulating plant extracts and evaluate the glucose-lowering potential.

METHODS

GNPs encapsulating plant extracts were prepared by desolvation method followed by adsorption. The GNPs were characterised by loading efficiency, loading capacity, particle size, zeta potential, SEM and FTIR. The glucose-lowering activity of GNPs was determined using oral glucose tolerance test in high-fat diet fed streptozotocin-induced Wistar rats.

RESULTS

Loading efficiency and capacity, particle mean diameter, and zeta potential of optimised GNPs 72.45 ± 13.03% w/w, 53.05 ± 26.16% w/w, 517 ± 48 nm and (-)23.43 ± 9.96 mV respectively. GNPs encapsulating aqueous extracts of C. grandis, S. auriculata, and ethanol 70% v/v extracts of M. koenigii showed glucose-lowering activity by 17.62%, 11.96% and 13.73% (p < 0.05) compared to the non-encapsulated extracts. FTIR analysis confirmed the encapsulation of phytoconstituents into GNPs. SEM imaging showed spherical GNPs (174 ± 46 nm).

CONCLUSION

GNPs encapsulating plant extracts show promising potential to be developed as nanonutraceuticals against diabetes.

A review on the hypoglycemic effect, mechanism and application development of natural dietary polysaccharides

Diabetes mellitus (DM) as one chronic metabolic disease was greatly increased over recent decades. The major agents treating diabetes have noticeable side effects as well as the tolerability problems. The bioactive dietary polysaccharides from abundant natural resources exhibit good hypoglycemic effect with rare adverse effects, which might serve as a candidate to prevent and treat diabetes. However, the correlations between the hypoglycemic mechanism of polysaccharides and their structure were not mentioned in several studies, what's more, most of the current hypoglycemic studies on polysaccharides were based on in vitro and in vivo experiments, and there was a lack of knowledge about the effects in human clinical trials. The aim of this review is to discuss recent literature about the variety of dietary polysaccharides with hypoglycemic activity, as well the mechanism of action and the structure-function relationship are highlighted. Meanwhile, the application of dietary polysaccharides in functional foods and clinical medicine are realized with an in-depth understanding. So as to promote the exploration of dietary polysaccharides in low glycemic healthy foods or clinical medicine to prevent and treat diabetes.

Phytochemical profiling, human insulin stability and alpha glucosidase inhibition of Gymnema latifolium leaves aqueous extract: Exploring through experimental and in silico approach

Diabetes mellitus Type 2 (DM2T) is a rapidly expanding metabolic endocrine disorder worldwide. It is caused due to inadequate insulin secretion by pancreatic beta cells as well as development of insulin resistance. This study aimed to investigate the anti-α-glucosidase, insulin stabilization effect, and non-cytotoxic nature of Gymnema latifolium leaf aqueous extract (GLAE). FTIR analysis revealed the functional groups of compounds present in GLAE. Through LC/ESI-MS/MS analysis, about 12 compounds which belongs to different classes, triterpene glycosides, flavonoids, phenolics, stilbene glycosides and chlorophenolic glycosides were identified. GLAE showed in vitro antioxidant activity. GLAE stabilized insulin by increasing its α-helical content. GLAE inhibited the mammalian α-glucosidase (IC50 = 144 μg/mL) activity through competitive mode (Ki = 61.30 µg/mL). GLAE did not affect the viability of normal cell line (Vero cell line) which shows its non-toxic nature. Molecular docking of phytocompounds identified in GLAE was done with human α-glucosidase and insulin. The top 2 compounds [Gymnema saponin V (GSV) and quercetin 3-(2-galloylglucoside) (QGG) with α-glucosidase; GSV and Z)-resveratrol 3,4'-diglucoside (RDG) with human insulin] with low binding free energy were subjected to 100 ns molecular dynamics simulation to ascertain the stable binding of ligand with protein. The MM/GBSA analysis revealed binding free energy of GSV/α-glucosidase and QGG /α-glucosidase to be - 20.9935 and, - 30.9461 kcal/mol, respectively. Altogether GLAE is valuable source of anti-α-glucosidase inhibitors and insulin stabilizing compounds, suggesting potential lead for further exploration as complementary medicine against DM2T.

Exploring the plant-derived bioactive substances as antidiabetic agent: An extensive review

Diabetes mellitus (DM) is a metabolic syndrome. Diabetes has become more common in recent years. Chemically generated drugs are used to lessen the effects of DM and its following repercussions due to unpleasant side effects such as weight gain, gastrointestinal issues, and heart failure. On the other hand, medicinal plants could be a good source of anti-diabetic medications. This article aims to determine any plant matrix's positive potential. Food restriction, physical activity, and the use of antidiabetic plant-derived chemicals are all being promoted as effective ways to manage diabetes because they are less expensive and have fewer or no side effects. This review focuses on antidiabetic plants, along with their bioactive constituent, chemically characterization, and plant-based diets for diabetes management. There is minimal scientific data about the mechanism of action of the plant-based product has been found. The purpose of this article is to highlight anti-diabetic plants and plant-derived bioactive compounds that have anti-diabetic properties. It also provides researchers with data that may be used to build future strategies, such as identifying promising bioactive molecules to make diabetes management easier.

Combination therapy of bioactive compounds with acarbose: A proposal to control hyperglycemia in type 2 diabetes

Type 2 diabetes (T2D) is a chronic metabolic disease with a high impact on public health and social welfare. Hyperglycemia is a characteristic of T2D that leads to different complications. Acarbose (ACB) reduces hyperglycemia by inhibiting α-amylase (AMY) and α-glucosidase (GLU) enzymes. However, ACB causes low adherence to treatment by patients with diabetes due to its side effects. Consequently, reducing the side effects produced by ACB without compromising its efficacy is a challenge in treating T2D. Bioactive compounds (BC) are safe and could decrease the side effects compared to antidiabetic drugs such as ACB. Nevertheless, their efficacy alone concerning that drug is unknown. The scientific advances have been directed toward searching for new approaches, such as combination therapies between BC and ACB. This review analyzes the combined therapy of BC (extracts or isolates) with ACB in inhibiting AMY and GLU as a proposal to control hyperglycemia in T2D. PRACTICAL APPLICATION: Postprandial hyperglycemia is one most typical signs of type 2 diabetes, and it can have significant consequences, including cardiovascular problems. Acarbose has side effects that lead to the abandonment of treatment. Bioactive compounds in extracts or isolated forms have become a viable option for controlling hyperglycemia without side effects, but their administration alone is insufficient. The scientific advances of acarbose/bioactive compound combination therapy as a proposal for controlling hyperglycemia in T2D were analyzed. The findings suggested that bioactive compounds combined with acarbose are effective when they function synergistically or additively; however, they are not recommended in therapy when they have an antagonistic effect.

Low-glycemic foods with wheat, barley and herbs (Terminalia chebula, Terminalia bellerica and Emblica officinalis) inhibit α-amylase, α-glucosidase and DPP-IV activity in high fat and low dose streptozotocin-induced diabetic rat

Wheat, barley or wheat + barley and herbs (Terminalia chebula, Terminalia bellerica and Emblica officinalis) based low-glycemic-index (low-GI) foods were developed and studied α-amylase, α-glucosidase and DPP-IV inhibition property in vitro and in the streptozotocin-induced diabetic rats. The GI of products ranged from 47 to 53 than control white bread (GI = 95). Total phenolic (20.1 ± 1 mg gallic acid/g dry wt.) and flavonoids (15.2 ± 1 mg quercetin/g dry wt.) were higher in wheat + barley than barley (17.2 ± 1; 13.6 ± 2) and wheat (16.9 ± 1; 14.9 ± 2) products. The in vitro α-amylase (4-10%), α-glucosidase (5-17%) and DPP-IV (3-26%) inhibition (IC₅₀) of methanol extracts were higher than the aqueous extracts. The fasting blood glucose (50.85, 33.22 and 24.52%) and oral glucose tolerance (AUC = 32.1, 36.04, and 27.73%) was lower in barley, wheat, and wheat + barley fed diabetic groups than diabetic control group (1571.5 ± 13.5 mg/dL/120 min). Feeding wheat, barley, and W + B foods for 60 days inhibited the intestinal α-amylase (1.2, 1.1 and 1.5-folds), α-glucosidase (1.3, 1.2 and 1.7-folds) and DPP-IV (1.6, 1.5 and 2.1-folds) activity compared to diabetic control. Low-GI foods lower the systemic glucose level, inhibit the glycolytic enzymes and DPP-IV activity and hence desirable for diabetes management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05231-0.

In vitro α-glucosidase inhibitory activity of Tamarix nilotica shoot extracts and fractions

α-glucosidase inhibitors represent an important class of type 2 antidiabetic drugs and they act by lowering postprandial hyperglycemia. Today, only three synthetic inhibitors exist on the market, and there is a need for novel, natural and more efficient molecules exhibiting this activity. In this study, we investigated the ability of Tamarix nilotica ethanolic and aqueous shoot extracts, as well as methanolic fractions prepared from aqueous crude extracts to inhibit α-glucosidase. Both, 50% ethanol and aqueous extracts inhibited α-glucosidase in a concentration-dependent manner, with IC₅₀ values of 12.5 μg/mL and 24.8 μg/mL, respectively. Importantly, α-glucosidase inhibitory activity observed in the T. nilotica crude extracts was considerably higher than pure acarbose (IC₅₀ = 151.1 μg/mL), the most highly prescribed α-glucosidase inhibitor on the market. When T. nilotica crude extracts were fractionated using methanol, enhanced α-glucosidase inhibitory activity was observed in general, with the highest observed α-glucosidase inhibitory activity in the 30% methanol fraction (IC₅₀ = 5.21 μg/mL). Kinetic studies further revealed a competitive reversible mechanism of inhibition by the plant extract. The phytochemical profiles of 50% ethanol extracts, aqueous extracts, and the methanolic fractions were investigated and compared using a metabolomics approach. Statistical analysis revealed significant differences in the contents of the crude extracts and fractions and potentially identified the molecules that were most responsible for these observed variations. Higher α-glucosidase inhibitory activity was associated with an enrichment of terpenoids, fatty acids, and flavonoids. Among the identified molecules, active compounds with known α-glucosidase inhibitory activity were detected, including unsaturated fatty acids, triterpenoids, and flavonoid glycosides. These results put forward T. nilotica as a therapeutic plant for type 2 diabetes and a source of α-glucosidase inhibitors.

Potential Mechanisms Involved in the Protective Effect of Dicaffeoylquinic Acids from Artemisia annua L. Leaves against Diabetes and Its Complications

Diabetes mellitus is a chronic disease affecting the globe and its incidence is increasing pandemically. The use of plant-derived natural products for diabetes management is of great interest. Polar fraction of Artemisia annua L. leaves has shown antidiabetic activity in vivo. In the present study, three major compounds were isolated from this polar fraction; namely, 3,5-dicaffeoylquinic acid (1); 4,5-dicaffeoylquinic acid (2), and 3,4- dicaffeoylquinic acid methyl ester (3), using VLC-RP-18 and HPLC techniques. The potential protective effects of these compounds against diabetes and its complications were investigated by employing various in vitro enzyme inhibition assays. Furthermore, their antioxidant and wound healing effectiveness were evaluated. Results declared that these dicaffeoylquinic acids greatly inhibited DPPIV enzyme while moderately inhibited α-glucosidase enzyme, where compounds 1 and 3 displayed the most prominent effects. In addition, compound 3 showed pronounced inhibition of α-amylase enzyme. Moreover, these compounds markedly inhibited aldose reductase enzyme and exerted powerful antioxidant effects, among which compound 3 exhibited the highest activity implying a notable potentiality in impeding diabetes complications. Interestingly, compounds 2 and 3 moderately accelerated scratch wound healing. Our findings suggest that these dicaffeoylquinic acids can be promising therapeutic agents for managing diabetes and its complications.

Antidiabetic and hypolipidemic potential of Campomanesia xanthocarpa seed extract obtained by supercritical CO2

Abstract Campomanesia xanthocarpa, a plant belonging to the Myrtaceae family, is popularly known as gabiroba. Leaves of gabiroba has been popularly used to treat various diseases, including inflammatory, renal, and digestive, among others. Additionally, studies have shown an effect to reduce blood cholesterol levels. The aim of this study was to evaluate the antihyperglycemic and hypolipidemic effects of Campomanesia xanthocarpa seed extract in hyperglycemic rats. The results showed that 400 mg/kg of seed extract was able to decrease blood glucose levels and to increase the muscular and hepatic glycogen content as well as to inhibit the sucrase and maltase activity. At doses of 200 mg/kg and 800 mg/kg, the activity of these enzymes was also reduced. In the lipid profile 400 mg/kg produced a decrease in total and LDL cholesterol serum levels; and with 200 mg/kg there was an increase in HDL cholesterol levels. The extract did not present hepatic and renal toxic effects at the different doses tested. The results suggest that the treatment with Campomanesia xanthocarpa seeds extract is useful in reducing glycemia, total cholesterol and LDL levels with potential adjuvant therapeutic in the treatment of diabetes and hypercholesterolemia, however, additional pharmacological and toxicological studies are still required.

Dietary supplementation with mung bean coat alleviates the disorders in serum glucose and lipid profile and modulates gut microbiota in high-fat diet and streptozotocin-induced prediabetic mice

As amajor by-product of mung bean processing, mung bean coat (MBC), which is rich in polyphenols and dietary fiber, is deemed to be mainly responsible for the health benefits of mung bean. However, its beneficial effects on the hyperglycemia, hyperlipidemia, and gut microbiota composition in prediabetic mice is not fully understood. The objective of this study was to investigate the efficacy of MBC in alleviating high-fat diet and streptozotocin-induced prediabetes. Herein, compared with the model control, dietary supplementation with MBC (3%, w/w) for 12 weeks significantly decreased the fasting blood glucose (24.60%), total cholesterol (15.72%), triglyceride (14.41%), and low-density lipoprotein cholesterol (22.45%). Furthermore, the improvements in glucose tolerance were reflected in the reduction of the area under the curve (AUC) and incremental AUC by approximately 23.08% and 51.18%, respectively. 16S rRNA gene sequencing of fecal microbiota suggested that MBC promoted the enrichment of beneficial bacteria (Roseburia and Bifidobacterium) and the production of short-chain fatty acids. All of the results from this study provided a scientific reference for avoiding the functional ingredients waste of MBC and expanding its application value.

Hypoglycemic effect of camel milk powder in type 2 diabetic patients: A randomized, double-blind, placebo-controlled trial

Fresh camel milk was widely accepted to help to prevent and control of diabetes, especially in Africa, Middle East, and cooler dry areas of Asia. In this study, type 2 diabetic patients were enrolled to supplement with 10 g of camel milk powder twice a day for 4 weeks (n = 14), cow milk powder served as the placebo (n = 13). It was found that camel milk supplement decreased fasting blood glucose, 2-hr postprandial blood glucose, serum content of total cholesterol, resistin, and lipocalin-2. There was also a significant increase in serum content of osteocrin, amylin, and GLP-1in camel milk group, indicating an improvement on adipose tissue and skeletal muscle. Camel milk powder supplement significantly enriched the relative abundance of Clostridium_sensu_stricto_1 and [Eubacterium]_eligens_group compared with cow milk after the 4-week intervention. This study suggested that camel milk powder can be used as a functional food help to treat type 2 diabetes.

The Brown Seaweeds of Scotland, Their Importance and Applications

More than 50% of the UK coastline is situated in Scotland under legislative jurisdiction; therefore, there is a great opportunity for regionally focused economic development by the rational use of sustainable marine bio-sources. We review the importance of seaweeds in general, and more specifically, wrack brown seaweeds which are washed from the sea and accumulated in the wrack zone and their economic impact. Rules and regulations governing the harvesting of seaweed, potential sites for harvesting, along with the status of industrial application are discussed. We describe extraction and separation methods of natural products from these seaweeds along with their phytochemical profiles. Many potential applications for these derivatives exist in agriculture, energy, nutrition, biomaterials, waste treatment (composting), pharmaceuticals, cosmetics and other applications. The chemical diversity of the natural compounds present in these seaweeds is an opportunity to further investigate a range of chemical scaffolds, evaluate their biological activities, and develop them for better pharmaceutical or biotechnological applications. The key message is the significant opportunity for the development of high value products from a seaweed processing industry in Scotland, based on a sustainable resource, and locally regulated.

Nutritional composition and proteomic analysis of soft-shelled turtle (Pelodiscus sinensis) egg and identification of oligopeptides with alpha-glucosidase inhibitory activity

This study aimed to explore nutritional compositions and proteomics of soft-shelled turtle (SST) egg, as well as identify potential antidiabetic oligopeptides with α-glucosidase inhibitory property. Results revealed that SST egg is a promising source of highly nutritious proteins and minerals (54.64% and 5.81% of dry matter, respectively). Further proteomic analysis showed SST egg proteins contained at least 9 protein families, such as transferrin/iron binding protein and immunoregulation-related protein. Hydrolysis by different enzymes, especially papain, remarkably increased α-glucosidase inhibitory activity and scavenging activity for ABTS, DPPH, hydroxyl and oxygen radicals of SST egg proteins. Peptides from papain hydrolysate were fractionated using ultrafiltration followed by reverse phase chromatography, and 16 peptides were identified in the most active fraction by LC-QTOF-MS/MS. Molecular docking revealed that 14 of these peptides could easily dock into the substrate-binding pocket and/or inhibitor binding sites of α-glucosidase with the docking score below -150 kcal/mol, indicating their potential α-glucosidase inhibitory properties. The five most abundant oligopeptides with potent interaction with α-glucosidase were further synthesized, and oligopeptides HNKPEVEVR, ARDASVLK and SGTLLHK strongly inhibited the activity of α-glucosidase (IC₅₀ of 56, 195 and 289 µmol/L, respectively). Therefore, oligopeptides from enzymatic hydrolysate of SST egg protein exhibit potential antidiabetic activity, making it a promising functional food ingredient.

Nutraceuticals: Transformation of Conventional Foods into Health Promoters/Disease Preventers and Safety Considerations

Nutraceuticals are essential food constituents that provide nutritional benefits as well as medicinal effects. The benefits of these foods are due to the presence of active compounds such as carotenoids, collagen hydrolysate, and dietary fibers. Nutraceuticals have been found to positively affect cardiovascular and immune system health and have a role in infection and cancer prevention. Nutraceuticals can be categorized into different classes based on their nature and mode of action. In this review, different classifications of nutraceuticals and their potential therapeutic activity, such as anti-cancer, antioxidant, anti-inflammatory and anti-lipid activity in disease will be reviewed. Moreover, the different mechanisms of action of these products, applications, and safety upon consumers including current trends and future prospect of nutraceuticals will be included.

Natural Antidiabetic Agents: Molecular Docking Study using the Extra Precision Method

Background:

Diabetes mellitus (DM) is the most severe, chronic metabolic disorder with abnormally elevated concentration of plasma glucose levels, leading to significant complications, such as diabetic neuropathy, retinopathy, and cardiovascular illnesses.

Objective:

Synthetic drugs have some disadvantages and limitations. Therefore, there is a continuous global and insisting need for new and better treatment options for Diabetes Mellitus.

Methods:

In this study, 42 natural anti-diabetic constituents like alkaloids, glycosides, and flavonoids were selected on the basis of mechanism of action on various molecular targets such as Glucokinase activator, Dipeptidyl peptidase 4 (DPP-4), peroxisome proliferator-activated receptors (PPARγ), and α-glucosidase inhibitor. To investigate the potential molecular targets for natural antidiabetcs agents, molecular docking study was carried out using the Glide module of Schrodinger Suit.

Results:

Interactions of specific amino acid of the targets with the atoms of the chemical constituents and their Gscore indicate the proper binding of chemical constituents with target. The results revealed that Myricetin, Quercetin ae interacts with active sites of the target chosen and can be used for the designing of novel compounds as anti-dibetics.

Conclusion:

Calculated GScore could be used as a preliminary tool for screening of anti-diabetic drugs before performing experimental activity.

Chemical characterization, cytotoxic, antioxidant, antimicrobial, and enzyme inhibitory effects of different extracts from one sage (Salvia ceratophylla L.) from Turkey: open a new window on industrial purposes

In the present study, the methanolic, hydro-methanolic, dichloromethane, hexane and aqueous extracts of Salvia ceratophylla L. (Family: Lamiaceae), a lemon-scented herb, were tested for total phenolic (TPC) and flavonoid content (TFC) and antioxidant activities were evaluated using a battery of assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity, total antioxidant capacity (TAC) (phosphomolybdenum) and metal chelating). Enzyme inhibitory effects were investigated using acetyl- (AChE), butyryl-cholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase as target enzymes. Regarding the cytotoxic abilities, HepG2, B164A5 and S17 cell lines were used. The phytochemical profile was conducted using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Our data showed that the methanolic aerial extracts possessed the highest phenolic (72.50 ± 0.63 mg gallic acid equivalent per g) and flavonoid (43.77 ± 1.09 mg rutin equivalent per g) contents. The hydro-methanolic aerial extract showed significant DPPH radical scavenging activity (193.40 ± 0.27 mg TE per g) and the highest reducing potential against CUPRAC (377.93 ± 2.38 mg TE per g). The best tyrosinase activity was observed with dichloromethane root extract (125.45 ± 1.41 mg kojic acid equivalent per g). Among the tested extracts, hexane root extract exerted the highest antimicrobial potential with a minimum inhibitory concentration value of 0.048 mg mL⁻¹. Methanolic root extract showed the lowest cytotoxicity (28%) against HepG2 cells. Phytochemical analysis revealed the presence of important polyphenolic compounds including luteolin, gallic acid, rosmarinic acid, to name a few. This research can be used as one methodological starting point for further investigations on this lemon-scented herb.

Our findings suggested that Salvia ceratophylla could be one potential raw material in industrial applications.

Effects of 22 traditional anti-diabetic medicinal plants on DPP-IV enzyme activity and glucose homeostasis in high-fat fed obese diabetic rats

The present study investigated the effects of hot water extracts of 22 medicinal plants used traditionally to treat diabetes on Dipeptidyl peptidase-IV (DPP-IV) activity both in vitro and in vivo in high-fat fed (HFF) obese-diabetic rats. Fluorometric assay was employed to determine the DPP-IV activity. For in vivo studies, HFF obese-diabetic rats were fasted for 6 h and blood was sampled at different times before and after the oral administration of the glucose alone (18 mmol/kg body weight) or with either of the four most active plant extracts (250 mg/5 ml/kg, body weight) or established DPP-IV inhibitors (10 μmol/5 ml/kg). DPP-IV inhibitors: sitagliptin, vildagliptin and diprotin A, decreased enzyme activity by a maximum of 95-99% (P<0.001). Among the 22 natural anti-diabetic plants tested, AnogeissusLatifolia exhibited the most significant (P<0.001) inhibitory activity (96 ± 1%) with IC50 and IC25 values of 754 and 590 μg/ml. Maximum inhibitory effects of other extracts: Aegle marmelos, Mangifera indica, Chloropsis cochinchinensis, Trigonella foenum-graecum and Azadirachta indica were (44 ±7%; 38 ± 4%; 31±1%; 28±2%; 27±2%, respectively). A maximum of 45% inhibition was observed with >25 μM concentrations of selected phytochemicals (rutin). A.latifolia, A. marmelos, T. foenum-graecum and M. indica extracts improved glucose tolerance, insulin release, reduced DPP-IV activity and increased circulating active GLP-1 in HFF obese-diabetic rats (P<0.05-0.001). These results suggest that ingestion of selected natural anti-diabetic plants, in particular A. latifolia, A. marmelos, T. foenum-graecum and M. indica can substantially inhibit DPP-IV and improve glucose homeostasis, thereby providing a useful therapeutic approach for the treatment of T2DM.

Anti-Inflammatory, Antioxidant and Enzyme Inhibition Activities in Correlation with Mycochemical Profile of Selected Indigenous Ganoderma spp. from Balkan Region (Serbia)

The aim of this research work was to study the bioactivity potentials (antioxidant, anti-inflammatory, and enzyme inhibitory) of ethanol (EtOH), water (H₂ O) and chloroform (CHCl₃ ) extracts of G. applanatum, G. lucidum, G. pfeifferi and G. resinaceum as well as their mycochemical profile: the total content of phenolics (TP) and sugars (TS) and LC/MS/MS detection of phenolics. LC/MS/MS profile showed that p-hydroxybenzoic and protocatechuic acids were mostly found. The highest ABTS and DPPH activities were detected in polar G. applanatum extracts (159.84±0.59 mg TE/g d.w., IC₅₀ =0.85±0.30 μg/mL, respectively), while G. resinaceum CHCl₃ extract was the most potent in NO assay (IC₅₀ =41.21±0.18-81.89±0.81 μg/mL). The highest TP and TS were generally determined in G. applanatum EtOH extracts. Enzyme inhibitory effects were determined in H₂ O extracts. Generally, CHCl₃ extracts showed the most powerful anti-inflammatory potential. These results suggest that analyzed species are a promising source of bioactive compounds and may be considered as candidates for new food supplements or drug formulations.

The biology of ergothioneine, an antioxidant nutraceutical

Ergothioneine (ERG) is an unusual thio-histidine betaine amino acid that has potent antioxidant activities. It is synthesised by a variety of microbes, especially fungi (including in mushroom fruiting bodies) and actinobacteria, but is not synthesised by plants and animals who acquire it via the soil and their diet, respectively. Animals have evolved a highly selective transporter for it, known as solute carrier family 22, member 4 (SLC22A4) in humans, signifying its importance, and ERG may even have the status of a vitamin. ERG accumulates differentially in various tissues, according to their expression of SLC22A4, favouring those such as erythrocytes that may be subject to oxidative stress. Mushroom or ERG consumption seems to provide significant prevention against oxidative stress in a large variety of systems. ERG seems to have strong cytoprotective status, and its concentration is lowered in a number of chronic inflammatory diseases. It has been passed as safe by regulatory agencies, and may have value as a nutraceutical and antioxidant more generally.

Cytotoxicity and insulin resistance reversal ability of biofunctional phytosynthesized MgO nanoparticles

The present study investigates the cytotoxicity of hexagonal MgO nanoparticles synthesized via Amaranthus tricolor leaf extract and spherical MgO nanoparticles synthesized via Amaranthus blitum and Andrographis paniculata leaf extracts. In vitro cytotoxicity analysis showed that the hexagonal MgO nanoparticles synthesized from A. tricolor extract demonstrated the least toxicity to both diabetic and non-diabetic cells at 600 μl/ml dosage. The viability of the diabetic cells (3T3-L1) after incubation with varying dosages of MgO nanoparticles was observed to be 55.3%. The viability of normal VERO cells was 86.6% and this stabilized to about 75% even after exposure to MgO nanoparticles dosage of up to 1000 μl/ml. Colorimetric glucose assay revealed that the A. tricolor extract synthesized MgO nanoparticles resulted in ~ 28% insulin resistance reversal. A reduction in the expression of GLUT4 protein at 54 KDa after MgO nanopaSrticles incubation with diabetic cells was observed via western blot analysis to confirm insulin reversal ability. Fluorescence microscopic analysis with propidium iodide and acridine orange dyes showed the release of reactive oxygen species as a possible mechanism of the cytotoxic effect of MgO nanoparticles. It was inferred that the synergistic effect of the phytochemicals and MgO nanoparticles played a significant role in delivering enhanced insulin resistance reversal capability in adipose cells.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

Comparative effect of nutraceuticals on lipid profile: a protocol for systematic review and network meta-analysis

INTRODUCTION

According to the common definition, nutraceuticals are components found in food that can act as therapeutic substances. Recently, the International Lipid Expert Panel published two position papers covering the topic of lipid-lowering nutraceuticals and their potential use as a complementary treatment in addition to statins or as an alternative treatment in statin-intolerant patients. The aim of this study was to compare the effect of different nutraceuticals on lipid profiles in a systematic review with pairwise and network meta-analyses.

METHODS AND ANALYSIS

Three databases, including PubMed, Embase and the Cochrane Central Register of Controlled Trials, will be searched without time or publication language restrictions. The estimated end date for the searches will be 29 March 2020. Each stage of the review, including the study section, data extraction, and risk of bias and quality of evidence assessments, will be performed in duplicate. Randomised controlled trials meeting the following criteria will be eligible for inclusion: (1) participants aged ≥18 years, (2) intervention with a selected nutraceutical (artichoke, berberine, bergamot, soluble fibres, green tea, garlic, lupin, plant sterols and stanols, red yeast rice, soybean, spirulina or a combination of the aforementioned nutraceuticals), (3) administration of the treatment in the form of capsules, pills, powders, solutions, tablets or enriched food items, (4) comparison with another nutraceutical or placebo, (5) intervention period ≥3 weeks and (6) lipid profile (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol, triglycerides) as an outcome. Random-effect pairwise and network meta-analyses will be used to summarise the relative effect of each nutraceutical in comparison to the effect of every other nutraceutical. Subgroup analyses will be stratified by age, sex, ethnicity, sample size, length of trial follow-up, baseline cholesterol level and presence of other comorbidities.

ETHICS AND DISSEMINATION

This review will summarise findings from primary studies, and therefore no ethics approval is required. The results will be presented at conferences as well as published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019132877.

Phenylpropanoid-Conjugated Triterpenoids from the Leaves of Actinidia arguta and Their Inhibitory Activity on α-Glucosidase

Actinidia arguta, commonly called hardy kiwifruit or kiwiberry, has cold-resistant properties and can be cultivated in Asia, including Korea. Seven new triterpenoids (2-4 and 8-11) along with eight known triterpenoids were isolated from the leaves of A. arguta through various chromatographic techniques. The new triterpenoids were defined as actiniargupenes A-C (2-4), actinidic acid derivatives with phenylpropanoid constituent units, dehydroisoactinidic acid (8), and actiniargupenes D-F (9-11), asiatic acid derivatives with phenylpropanoid substituents, on the basis of 1D and 2D NMR and MS data. Among the triterpenoids, those with a phenylpropanoid constituent unit showed inhibitory activity on α-glucosidase, which suggested the importance of the phenylpropanoid moiety. Molecular docking analysis demonstrated the interaction between the 4'-OH group of the phenylpropanoid moiety and α-glucosidase.

The Inhibition of Amylase and ACE Enzyme and the Reduction of Immunoreactivity of Sourdough Bread

This study examines the potential health benefits of different types of wheat sourdough bread against diseases of civilization. Celiac disease, diabetes and hypertension affect large numbers of the world's population, increasing demand for novel treatments and ways of improving patient welfare. Different types of artisan breads were subjected to in vitro simulated digestion prior to analysis. The G12 test and ELISA with human sera were used for immunoreactivity analysis. The activity of α-amylase inhibitors and angiotensin-converting enzymes (ACE) was also assessed. The addition of sourdough to the analyzed wheat bread raised the content of α-amylase inhibitors and angiotensin-converting enzyme inhibitors while reducing their immunoreactivity. However, despite decreases in the antigenicity of the wheat flour proteins, the sera showed various reactions, depending on the individual patient's susceptibility to gluten.

Metabolic flux analysis of secondary metabolism in plants

Numerous secondary metabolites from plants are important for their medicinal, nutraceutical or sensory properties. Recently, significant progress has been made in the identification of the genes and enzymes of plant secondary metabolic pathways. Hence, there is interest in using synthetic biology to enhance the production of targeted valuable metabolites in plants. In this article, we examine the contribution that metabolic flux analysis will have on informing the rational selection of metabolic engineering targets as well as analysis of carbon and energy efficiency. Compared to microbes, plants have more complex tissue, cellular and subcellular organization, making precise metabolite concentration measurements more challenging. We review different techniques involved in quantifying flux and provide examples illustrating the application of the techniques. For linear and branched pathways that lead to end products with low turnover, flux quantification is straightforward and doesn’t require isotopic labeling. However, for metabolites synthesized via parallel pathways, there is a requirement for isotopic labeling experiments. If the fed isotopically labeled carbons don’t scramble, one needs to apply transient label balancing methods. In the transient case, it is also necessary to measure metabolite concentrations. While flux analysis is not able to directly identify mechanisms of regulation, it is a powerful tool to examine flux distribution at key metabolic nodes in intermediary metabolism, detect flux to wasteful side pathways, and show how parallel pathways handle flux in wild-type and engineered plants under a variety of physiological conditions.

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Plant secondary metabolites have high economic value to human health and pleasure.

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Plant secondary metabolites are synthesized by pathways in subcellular compartments.

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Metabolic flux analysis can guide the selection of metabolic engineering targets.

Reduction of blood glucose by plant extracts and their use in the treatment of diabetes mellitus; discrepancies in effectiveness between animal and human studies

ETHNOPHARMACOLOGICAL RELEVANCE

The global problem of diabetes, together with the limited access of large numbers of patients to conventional antidiabetic medicines, continues to drive the search for new agents. Ancient Asian systems such as traditional Chinese medicine, Japanese Kampo medicine, and Indian Ayurvedic medicine, as well as African traditional medicine and many others have identified numerous plants reported anecdotally to treat diabetes; there are probably more than 800 such plants for which there is scientific evidence for their activity, mostly from studies using various models of diabetes in experimental animals.

AIM OF THE REVIEW

Rather than a comprehensive coverage of the literature, this article aims to identify discrepancies between findings in animal and human studies, and to highlight some of the problems in developing plant extract-based medicines that lower blood glucose in patients with diabetes, as well as to suggest potential ways forward.

METHODS

In addition to searching the 2018 PubMed literature using the terms 'extract AND blood glucose, a search of the whole literature was conducted using the terms 'plant extracts' AND 'blood glucose' AND 'diabetes' AND 'double blind' with 'clinical trials' as a filter. A third search using PubMed and Medline was undertaken for systematic reviews and meta-analyses investigating the effects of plant extracts on blood glucose/glycosylated haemoglobin in patients with relevant metabolic pathologies.

FINDINGS

Despite numerous animal studies demonstrating the effects of plant extracts on blood glucose, few randomised, double-blind, placebo-controlled trials have been conducted to confirm efficacy in treating humans with diabetes; there have been only a small number of systematic reviews with meta-analyses of clinical studies. Qualitative and quantitative discrepancies between animal and human clinical studies in some cases were marked; the factors contributing to this included variations in the products among different studies, the doses used, differences between animal models and the human disease, and the impact of concomitant therapy in patients, as well as differences in the duration of treatment, and the fact that treatment in animals may begin before or very soon after the induction of diabetes.

CONCLUSION

The potential afforded by natural products has not yet been realised in the context of treating diabetes mellitus. A systematic, coordinated, international effort is required to achieve the goal of providing anti-diabetic treatments derived from medicinal plants.

Aspergillus flavus as a Model System to Test the Biological Activity of Botanicals: An Example on Citrullus colocynthis L. Schrad. Organic Extracts

Citrullus colocynthis L. Schrader is an annual plant belonging to the Cucurbitaceae family, widely distributed in the desert areas of the Mediterranean basin. Many pharmacological properties (anti-inflammatory, anti-diabetic, analgesic, anti-epileptic) are ascribed to different organs of this plant; extracts and derivatives of C. colocynthis are used in folk Berber medicine for the treatment of numerous diseases-such as rheumatism arthritis, hypertension bronchitis, mastitis, and even cancer. Clinical studies aimed at confirming the chemical and biological bases of pharmacological activity assigned to many plant/herb extracts used in folk medicine often rely on results obtained from laboratory preliminary tests. We investigated the biological activity of some C. colocynthis stem, leaf, and root extracts on the mycotoxigenic and phytopathogenic fungus Aspergillus flavus, testing a possible correlation between the inhibitory effect on aflatoxin biosynthesis, the phytochemical composition of extracts, and their in vitro antioxidant capacities.

AMPK activation is involved in hypoglycemic and hypolipidemic activities of mogroside-rich extract from Siraitia grosvenorii (Swingle) fruits on high-fat diet/streptozotocin-induced diabetic mice

AMPK is involved in hypoglycemic and hypolipidemic activities of mogrosides from Siraitia grosvenorii (Swingle) fruits on diabetic mice.

Circadian dysrhythmia-linked diabetes mellitus: Examining melatonin’s roles in prophylaxis and management

Diabetes mellitus is a chronic, life-threatening metabolic disorder that occurs worldwide. Despite an increase in the knowledge of the risk factors that are associated with diabetes mellitus, its worldwide prevalence has continued to rise; thus, necessitating more research into its aetiology. Recent researches are beginning to link a dysregulation of the circadian rhythm to impairment of intermediary metabolism; with evidences that circadian rhythm dysfunction might play an important role in the aetiology, course or prognosis of some cases of diabetes mellitus. These evidences thereby suggest possible relationships between the circadian rhythm regulator melatonin, and diabetes mellitus. In this review, we discuss the roles of the circadian rhythm in the regulation of the metabolism of carbohydrates and other macronutrients; with emphasis on the importance of melatonin and the impacts of its deficiency on carbohydrate homeostasis. Also, the possibility of using melatonin and its analogs for the “prophylaxis” or management of diabetes mellitus is also considered.