Trigonelline and vildagliptin antidiabetic effect: improvement of insulin signalling pathway

The Role of Fenugreek in the Management of Type 2 Diabetes

The number of people diagnosed with type 2 diabetes is on the increase worldwide. Of growing concern, the prevalence of type 2 diabetes in children and youths is increasing rapidly and mirrors the increasing burden of childhood obesity. There are many risk factors associated with the condition; some are due to lifestyle, but many are beyond our control, such as genetics. There is an urgent need to develop better therapeutics for the prevention and management of this complex condition since current medications often cause unwanted side effects, and poorly managed diabetes can result in the onset of related comorbidities. Naturally derived compounds have gained momentum for preventing and managing several complex conditions, including type 2 diabetes. Here, we provide an update on the benefits and limitations of fenugreek and its components as a therapeutic for type 2 diabetes, including its bioavailability and interaction with the microbiome.

Synthesis and Anti-Diabetic Activity of an 8-Purine Derivative as a Novel DPP-4 Inhibitor in Obese Diabetic Zücker Rats

Type 2 diabetes mellitus (T2DM) is one of the world's principal metabolic diseases characterized by chronic hyperglycemia. The gut incretin hormones, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP), which has been proposed as a new treatment for T2DM, are extensively metabolized by Dipeptidyl peptidase 4 (DPP-4). Inhibitors of DPP-4 block the degradation of GLP-1 and GIP and may increase their natural circulating levels, favoring glycemic control in T2DM. A novel and potent selective inhibitor of DPP-4 with an 8-purine derived structure (1) has been developed and tested in vitro and in vivo in Zücker obese diabetic fatty (ZDF) rats, an experimental model of the metabolic syndrome and T2DM to assess the inhibitory activity using vildagliptin as reference standard. ZDF rats were subdivided into three groups (n = 7/group), control (C-ZDF), and those treated with compound 1 (Compound1-ZDF) and with vildagliptin (V-ZDF), both at 10 mg/kg/d rat body weight, in their drinking water for 12 weeks, and a group of lean littermates (ZL) was used. ZDF rats developed DM (fasting hyperglycemia, 425 ± 14.8 mg/dL; chronic hyperglycemia, HbA1c 8.5 ± 0.4%), compared to ZL rats. Compound 1 and vildagliptin reduced sustained HbAl1c (14% and 10.6%, P < 0.05, respectively) and fasting hyperglycemia values (24% and 19%, P < 0.05, respectively) compared to C-ZDF group (P < 0.001). Compound 1 and vildagliptin have shown a potent activity with an IC50 value of 4.92 and 3.21 µM, respectively. These data demonstrate that oral compound 1 administration improves diabetes in ZDF rats by the inhibitory effect on DPP-4, and the potential to be a novel, efficient and tolerable approach for treating diabetes of obesity-related T2DM, in ZDF rats.

Pharmacological Activities, Therapeutic Effects, and Mechanistic Actions of Trigonelline

Trigonelline (TRG) is a natural polar hydrophilic alkaloid that is found in many plants such as green coffee beans and fenugreek seeds. TRG potentially acts on multiple molecular targets, including nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor γ, glycogen synthase kinase, tyrosinase, nerve growth factor, estrogen receptor, amyloid-β peptide, and several neurotransmitter receptors. In this review, we systematically summarize the pharmacological activities, medicinal properties, and mechanistic actions of TRG as a potential therapeutic agent. Mechanistically, TRG can facilitate the maintenance and restoration of the metabolic homeostasis of glucose and lipids. It can counteract inflammatory constituents at multiple levels by hampering pro-inflammatory factor release, alleviating inflammatory propagation, and attenuating tissue injury. It concurrently modulates oxidative stress by the blockage of the detrimental Nrf2 pathway when autophagy is impaired. Therefore, it exerts diverse therapeutic effects on a variety of pathological conditions associated with chronic metabolic diseases and age-related disorders. It shows multidimensional effects, including neuroprotection from neurodegenerative disorders and diabetic peripheral neuropathy, neuromodulation, mitigation of cardiovascular disorders, skin diseases, diabetic mellitus, liver and kidney injuries, and anti-pathogen and anti-tumor activities. Further validations are required to define its specific targeting molecules, dissect the underlying mechanistic networks, and corroborate its efficacy in clinical trials.

Risk Assessment of Trigonelline in Coffee and Coffee By-Products

Trigonelline is a bioactive pyridine alkaloid that occurs naturally in high concentrations in coffee (up to 7.2 g/kg) and coffee by-products (up to 62.6 g/kg) such as coffee leaves, flowers, cherry husks or pulp, parchment, silver skin, and spent grounds. In the past, coffee by-products were mostly considered waste and discarded. In recent years, however, the use of coffee by-products as food has attracted interest because of their economic and nutritional value and the environmental benefits of sustainable resource use. Their authorization as so-called novel foods in the European Union may lead to increased oral exposure of the general population to trigonelline. Therefore, the aim of this review was to assess the risk to human health of acute and chronic exposure to trigonelline from coffee and coffee by-products. An electronic literature search was performed. Current toxicological knowledge is limited, with few human data available and a lack of epidemiological and clinical studies. There was no evidence of adverse effects after acute exposure. No conclusion can be drawn on chronic exposure to isolated trigonelline due to the lack of data. However, trigonelline ingested as a component of coffee and coffee by-products appears to be safe for human health, based on the safe traditional use of these products.

The neuroprotective and antidiabetic effects of trigonelline: A review of signaling pathways and molecular mechanisms

The global epidemic of diabetes has brought heavy pressure on public health. New effective anti-diabetes strategies are urgently needed. Trigonelline is the main component of fenugreek, which has been proved to have a good therapeutic effect on diabetes and diabetic complications. Trigonelline achieves amelioration of diabetes, the mechanisms of which include the modulation of insulin secretion, a reduction in oxidative stress, and the improvement of glucose tolerance and insulin resistance. Besides, trigonelline has been reported to be a neuroprotective agent against many neurologic diseases including Alzheimer's disease, Parkinson's disease, stroke, and depression. Concerning the potential therapeutic effects of trigonelline, comprehensive clinical trials are warranted to evaluate this valuable molecule.

Alkaloids as Promising Agents for the Management of Insulin Resistance: A Review

BACKGROUND

Insulin resistance is one of the main factors that lead to the development of type 2 diabetes mellitus (T2DM). The effect of alkaloids on insulin resistance has been extensively examined according to multiple scientific researches.

OBJECTIVE

In this work, we aimed to summarize the interesting results from preclinical and clinical studies that assessed the effects of natural alkaloids (berberine, nigelladine A, piperine, trigonelline, capsaicin, nuciferine, evodiamine, mahanine, and magnoflorine) on impaired insulin sensitivity and worsened insulin resistance, which play a pivotal role in the pathogenesis of type 2 diabetes.

METHODS

In the current review, PubMed, ScienceDirect, Springer, and Google Scholar databases were used. The inclusion criteria were based on the following keywords and phrases: insulin sensitivity, insulin resistance, alkaloids and insulin resistance, alkaloids and type 2 diabetes, mechanisms of action, and alkaloids.

RESULTS

The outcomes reported in this review demonstrated that the selected alkaloids increased insulin sensitivity and reduced insulin resistance in vitro and in vivo evidence, as well as in clinical trials, through improving insulin-signaling transduction mainly in hepatocytes, myocytes, and adipocytes, both at cellular and molecular levels. Insulin signaling components (InsR, IRS-1, PI3K, Akt, etc.), protein kinases and phosphatases, receptors, ion channels, cytokines, adipokines, and microRNAs, are influenced by alkaloids at transcriptional and translational levels, also in terms of function (activity and/or phosphorylation). Multiple perturbations associated with insulin resistance, such as ectopic lipid accumulation, inflammation, ER stress, oxidative stress, mitochondrial dysfunction, gut microbiota dysbiosis, and β-cell failure, are reversed after treatment with alkaloids. Furthermore, various indices and tests are employed to assess insulin resistance, including the Matsuda index, insulin sensitivity index (ISI), oral glucose tolerance test (OGTT), and insulin tolerance test (ITT), which are all enhanced by alkaloids. These improvements extend to fasting blood glucose, fasting insulin, and HbA1c levels as well. Additionally, the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and the Homeostasis Model Assessment of β-cell function (HOMA-β) are recognized as robust markers of insulin sensitivity and β-cell function, and it is noteworthy that alkaloids also lead to improvements in these two markers.

CONCLUSION

Based on the findings of the current review, alkaloids may serve as both preventive and curative agents for metabolic disorders, specifically type 2 diabetes. Nonetheless, there is an urgent need for additional clinical trials to explore the potential benefits of alkaloids in both healthy individuals and those with type 2 diabetes. Additionally, it is crucial to assess any possible side effects and interactions with antidiabetic drugs.

Trigonelline reverses high glucose-induced proliferation, fibrosis of mesangial cells via modulation of Wnt signaling pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of the end-stage renal disease (ESRD). The proliferation and apoptosis of mesangial cells induced by the activated Wnt/β-catenin pathway is crucial in DN. Trigonelline (TRL) is an alkaloid that has been shown to decrease proteinuria and protect the renal function in DN. However, the effect of TRL on the Wnt/β-catenin pathway of mesangial cells is unclear.

METHODS

As a cellular DN model, human mesangial cells (HMCs) were treated with high-glucose (HG). β-Catenin plasmid and control knockdown plasmids were transfected into HG-treated HMCs as β-catenin pcDNA and β-catenin siRNA groups, respectively. Cell viability was measured by MTT assay. Flow cytometry was used to detect the cell cycle. Cell apoptosis was evaluated by flow cytometry and terminal dUTP transferase nick end labeling (TUNEL) assay. mRNA expression of Wnt1, Wnt3a, Wnt4, Wnt5a, β-catenin, TCF4, Cyclin D1, and CDK4 were detected by qRT-PCR. Protein expression of Wnt4, Wnt5a, nucleus-β-catenin, TCF4, Cyclin D1, and CDK4 were detected by western blotting.

RESULTS

TRL significantly inhibited HG-induced HMCs viability over three-time points measured (24, 48, and 72 h). In addition, TRL suppressed the levels of fibronectin (FN) and collagen IV (Col IV) in HG-stimulated HMCs. Furthermore, TRL efficiently inhibited the activation of the Wnt/β-catenin signaling pathway in HG-stimulated HMCs. Taken together, these data indicated that TRL inhibited HG-induced HMCs proliferation and ECM expression via the modulation of the Wnt signaling pathway.

CONCLUSIONS

TRL reduces HG-induced cell injury by regulating the Wnt/β-catenin signaling pathway.

Coffee constituents with antiadipogenic and antidiabetic potentials: A narrative review

Coffee consumption has been associated with the reduction of several chronic diseases, including type 2 diabetes mellitus (T2DM) and obesity. The aim of this review was to summarize the research conducted in the last five years (or older, when appropriate) on the relationship between the consumption of coffee bioactive compounds, obesity, and T2DM. A bibliographic search was performed using the Web of Sciences, Scopus, and Google Scholar. Keywords used were "caffeine," "coffee," "coffee consumption," "coffee extraction," "coffee bioactive components," "chlorogenic acid," "obesity," "antidiabetic," and "antiadipogenic." Epidemiological, clinical, animal, and cell culture studies were reviewed. Caffeine, chlorogenic acid, and diterpenes have been identified as potential bioactive compounds in coffee that exhibit antiadipogenic and antidiabetic effects. The concentration of these compounds in coffee depends on the coffee preparation method. The relationship between coffee consumption and obesity risk is inconsistent, as not all results report a positive association. The addition of sugar and cream may be responsible for these mixed results. The consumption of coffee and its constituents is consistently associated with a lower T2DM risk. Caffeine, chlorogenic acids, and diterpenes have antidiabetic properties and are associated with these effects. The available data do not allow us to draw a conclusion on the effect of coffee or its constituents on adipogenesis. Therefore, more tightly controlled human intervention studies are required for a deeper understanding about this relationship.

Amelioration of related complications by the combined usage of Gymnadenia orchidis Lindl and pumpkin seed in type 2 diabetic mice

BACKGROUND

Inflammation, insulin resistance, hyperinsulinemia and cell damage are the major patho-physiological reasons behind type 2 diabetes (T2DM), which is one of the most prevalent non communicable metabolic disorders in the world. Oral hypoglycemic drugs and insulin shots are usually exercised to treat the diabetic patients but it produces many side effects. Thereby paving the way for natural hypoglycemic agents; a Himalayan herb and alternative nutritional therapy; low glycaemic indexed pumpkin seed, are used in combination for a better management of the disease.

OBJECTIVES

To explore the combined efficacy of Gymnadenia orchidis Lindl root Salep and low-glycemic indexed-pumpkin seeds in better management of T2DM and associated complications.

METHODS

Balb/c mice were randomly allocated to six different groups (n=5). Streptozotocin along with high-fat-diet was used to induce T2DM. The experimental animals were supplemented with low-glycemic food or root Salep (200 mg/kg body weight) or combination of both according to their groups for 21 days, post which various biochemical tests were performed.

RESULTS

T2DM augmented the IL-6, IFN-γ, TNF-α, BAX, Insulin levels, and HOMA-IR with concurrent reduction of IL-4, QUICKI, Bcl-2, estradiol and progesterone levels. FACS revealed augmented cellular damage in T2DM mice. Interestingly, root Salep and pumpkin seeds normalized those parameters in T2DM animals suggesting significant (p<0.001) improvement of immunity of the diseased animals and ameliorated associated complications.

CONCLUSIONS

Root Salep and pumpkin seed display synergism among binomial set of herbal agents which may be safely used for T2DM management.

Natural Alkaloids and Diabetes Mellitus: A Review

BACKGROUND

The use of herbal therapies for treatment and management of diabetes mellitus and complications associated with this chronic condition is increasing. Plants contain a bounty of phytochemicals that have been proven to be protective by reducing the risk of various ailments and diseases, including alkaloids. Moreover, alkaloids are known to be among the oldest natural products used by humans for highlighting drugs that play crucial roles as therapeutic agents. The reason for this expanding interest and uses of alkaloids as a part of plant natural compounds-based treatments is that a significant proportion of diabetic patients do not respond very well to conventional therapeutic medication. Furthermore, other explanations to this fact are the cost of medication, side-effects, accessibility, and availability of health facilities and drugs and the inefficiency of these medicines in certain cases.

OBJECTIVE

In this study we aimed to review the literature on the valuable effects of herbs and plants and their isolated alkaloids compounds as medication for management of diabetes, a prevalent risk factor for several other disorders and illnesses.

METHODS

In the current review, PubMed, ScienceDirect, Springer and google scholar databases were used and the criterion for inclusion was based on the following keywords and phrases: diabetes, hyperglycemia, complications of diabetes, alkaloids, antidiabetic alkaloids, hypoglycemic alkaloids, alkaloids and complications of diabetes mellitus, mechanisms of action and alkaloids.

RESULTS

In the current review, we demonstrate that alkaloids in the form of extracts and isolated molecules obtained from a large variety of species demonstrated their efficiency for improving raises in blood glucose either in animal models via experimental studies or in human subjects via clinical trials. Medicinal species as chillies (Capsicum annuum), turmeric (Curcuma longa), barberry (Berberis vulgaris) and cress (Lepidium sativum) are among the most common and therapeutic plants used for controlling diabetes that were the subject of several experimental and clinical investigations. Whereas, isolated alkaloids such as berberine, capsaicin and trigonelline have received more interest in this field. Interestingly, the therapeutic impact of alkaloids against blood glucose pathogenesis is mediated through a variety of signaling cascades and pathways, via inhibiting or stimulating diversity of systems such as inhibition of α-glucosidase enzyme, blockade of PTP- 1B, deactivation of DPP-IV, increasing insulin sensitivity and modulating the oxidative stress.

CONCLUSION

Based on the findings of the present review, alkaloids could be used as preventive and curative agents in the case of endocrine disorders, particularly diabetes and could play a promoting function for the discovery of new antidiabetic agents.

Indian Traditional medicinal plants as a source of potent Anti-diabetic agents: A Review

Objective

The present review aims to provide an overview of traditional medicinal plants known to be of anti-diabetic potential.

Methods

A literature search was conducted using the scientific databases including PubMed, EMBASE and google scholar and a total of fifty herbs have been described and their possible mechanism of anti-diabetic action has been mentioned. Among them, in-depth discussion on five most potent anti-diabetic herbs has been provided with respect to their mechanism of action, in-vivo studies and clinical efficacies.

Results

The present review has highlighted the usefulness of the herbal source for the treatment and management of diabetes mellitus. With the help of previous literature published on In-vivo animal studies and human clinical studies; the effectiveness of Gymnema sylvestre, Momordica charantia, Trigonella foenum graecum, Tinospora cordifolia and Curcuma longa in the treatment and management of Diabetes has been proved.

Conclusion

Based on this review it can be concluded that herbs can serve as more efficient, safer, and cost-effective adjuvant therapy in the management and treatment of diabetes. Further investigations mainly focusing on the isolation of phytocompounds from these herbs can lead to the discovery of newer antidiabetic agents.

Advances on application of fenugreek seeds as functional foods: Pharmacology, clinical application, products, patents and market

Trigonella foenum-graecum L. (fenugreek) is one of the oldest applied medicinal herbs. Significant pharmacological and clinical evidence have highlighted the medicinal application of fenugreek. Explore the current knowledge regarding the bioactivity (animal aspects) and clinical application of fenugreek and its bioactive components, as well as the products, markets and patents related to fenugreek. This review highlights the phytochemicals, bioactivity (animal aspects) and clinical application of fenugreek from recent literatures and products, markets and patents from database. Until now, more than 100 phytochemicals have been isolated from fenugreek seeds, mainly including polysaccharides, saponins, alkaloids, phenolic acids, and flavonoids. Fenugreek extract and its bioactive compounds showed excellent antidiabetic activity and anti-obesity activity in animal and human study. Although the fenugreek seed has been used as TCM raw materials for a long time of period in China, China is lacking the research of fenugreek in both depth and width.

LC-MS/MS analysis and network pharmacology of Trigonella foenum-graecum - A plant from Ayurveda against hyperlipidemia and hyperglycemia with combination synergy

BACKGROUND

The seed of Trigonella foenum-graecum L. (Methika in Sanskrit) is a well known kaphahara (balancing kapha) herb in Ayurveda indicated in Prameha or early diabetes mellitus. It is also useful in obesity and reduces lipid level of blood.

PURPOSE

We aimed to explore the metabolites present in the plant extract and to establish the combination synergy and the network pharmacology along with the underlying the mechanism of action involved.

STUDY DESIGN

LC-MS/MS based metabolite screening followed by ADME screening and finally network pharmacology exploration of the mechanism of action involved against hyperlipidemia and hypolipidemia with neighbourhood based combination synergy approach.

METHODS

Ethanolic extract of Trigonella foenum-graecum L. (TFHE) was subjected to LC-MS/MS analysis to identify the active constituents. Oral bioavailability and drug likeness was screened for all the compounds. Databases- Binding DB, DAVID, KEGG and STRING were used to gather information to develop the networks. The networks were constructed using Cytoscape 3.2.1. Combination synergy analysis was performed with the help of Cytoscape network analyzer tool with neighbourhood approach.

RESULTS

The LC-MS/MS analysis identified 13 compounds which were found to be bio-available and drug like following the QED and Veber drug likeness parameters. The pathway analysis showed enrichment for different pathways like MAPK pathway (p-4.69E-07), JAK-STAT pathway (p-6.30E-05), Adipocytokine (p-0.00179), Type 2 Diabetes mellitus (0.00441), Insulin signalling pathway (p-0.0121), mTOR signalling pathway (p-0.000378), which are all connected to hyperlipidemia and hyperglycemia. The combination synergy network identified 23 targets interacting with 13 compounds based on a network neighbourhood approach.

CONCLUSION

The network pharmacology analysis strongly suggested the multimode evidences that TFHE largely works on the insulin signalling pathway and mainly based on its antioxidant potential due to its interaction with carbonic anhydrase. Various compounds were found to be interacting with key proteins that activates EGFR/AKT/mTOR signalling cascade which has therapeutic implication in hyperglycemia and hyperlipidemia. The combination synergy network analysis based on neighbourhood approach can help us in further understanding mechanism of multi-molecular fixed dose combinations.

Trigonelline mitigates lipopolysaccharide-induced learning and memory impairment in the rat due to its anti-oxidative and anti-inflammatory effect

Brain inflammation is associated with cognitive dysfunction, especially in elderly. Trigonelline is a plant alkaloid and a major component of coffee and fenugreek with anti-diabetic, antioxidant, anti-inflammatory, and neuroprotective effects. In this study, the beneficial effect of trigonelline against lipopolysaccharide (LPS)-induced cognitive decline was assessed in the rat. LPS was injected i.p. at a dose of 500 μg/kg to induce neuroinflammation and trigonelline was administered p.o. at doses of 20, 40, or 80 mg/kg/day 1 h after LPS that continued for one week. Trigonelline-treated LPS-challenged rats showed improved spatial recognition memory in Y maze, discrimination ratio in novel object discrimination test, and retention and recall in passive avoidance paradigm. Additionally, trigonelline lowered hippocampal malondialdehyde (MDA) and acetylcholinesterase (AChE) activity and improved superoxide dismutase (SOD), catalase, and glutathione (GSH). Furthermore, trigonelline depressed hippocampal nuclear factor-kappaB (NF-κB), toll-like receptor 4 (TLR4), and tumor necrosis factor α (TNF α) in LPS-challenged rats. All of the effects of trigonelline followed a dose-dependent pattern and in some aspects, it acted even better than the routinely-used anti-inflammatory drug dexamethasone. Collectively, trigonelline is capable to diminish LPS-induced cognitive decline via suppression of hippocampal oxidative stress and inflammation and appropriate modulation of NF-κB/TLR4 and AChE activity.

Trigonelline insulates against oxidative stress, proinflammatory cytokines and restores BDNF levels in lipopolysaccharide induced cognitive impairment in adult mice

Neuroinflammation is said to play a pivotal role in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Trigonelline (TRG) is a naturally occurring alkaloid, commonly isolated from fenugreek and coffee beans. In the present study, we investigated whether TRG exerts neuroprotective action against LPS mediated cognitive impairment. Mice pretreated with TRG (50 and 100 mg/kg po) were administered with LPS (250 μg/kg ip) for 7 days. Memory was assessed in the Morris water maze (MWM) and Y maze. LPS administration caused poor memory retention in MWM and Y maze paradigms, and resulted in marked oxidative stress as evidenced by decrease in superoxide dismutase (SOD), reduced glutathione (GSH) levels and increased lipid peroxidation in the hippocampus and cortex. Cholinergic involvement during neuroinflammation was evaluated by measuring levels of acetylcholinesterase (AChE) enzyme. TRG treatment at both the doses reversed LPS induced behavioral and memory disturbances, significantly decreased the oxidative stress and AChE levels in both the hippocampus and cortex. LPS administration also elevated the tumour necrosis factor (TNF-α) and interleukin -6 (IL-6) levels, whereas brain derived neurotrophic factor (BDNF) levels were significantly depleted. TRG pretreatment led to decreased TNF-α and IL-6 levels and caused a significant upregulation of BDNF levels. In conclusion, present study highlights the promising neuroprotective role of TRG against LPS mediated cognitive impairment which could be attributed to reduced oxidative stress, inhibition of proinflammatory cytokines and restoration of BDNF levels.