Polydatin improves glucose and lipid metabolism in experimental diabetes through activating the Akt signaling pathway

The PI3K/Akt signaling axis and type 2 diabetes mellitus (T2DM): From mechanistic insights into possible therapeutic targets

Type 2 diabetes mellitus (T2DM) is an immensely debilitating chronic disease that progressively undermines the well-being of various bodily organs and, indeed, most patients succumb to the disease due to post-T2DM complications. Although there is evidence supporting the activation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway by insulin, which is essential in regulating glucose metabolism and insulin resistance, the significance of this pathway in T2DM has only been explored in a few studies. The current review aims to unravel the mechanisms by which different classes of PI3Ks control the metabolism of glucose; and also to discuss the original data obtained from international research laboratories on this topic. We also summarized the role of the PI3K/Akt signaling axis in target tissues spanning from the skeletal muscle to the adipose tissue and liver. Furthermore, inquiries regarding the impact of disrupting this axis on insulin function and the development of insulin resistance have been addressed. We also provide a general overview of the association of impaired PI3K/Akt signaling pathways in the pathogenesis of the most prevalent diabetes-related complications. The last section provides a special focus on the therapeutic potential of this axis by outlining the latest advances in active compounds that alleviate diabetes via modulation of the PI3K/Akt pathway. Finally, we comment on the future research aspects in which the field of T2DM therapies using PI3K modulators might be developed.

Effects of Fermented Polygonum cuspidatum on the Skeletal Muscle Functions

Plant extract fermentation is widely employed to enhance the nutritional and pharmaceutical value of functional foods. Polygonum cuspidatum (Pc) contains flavonoids, anthraquinones, and stilbenes, imparting protective effects against inflammatory diseases, cancer, diabetes, and cardiovascular diseases. However, the effects of fermented Pc on skeletal muscle strength remain unexplored. In this study, we generated fermented Pc using a complex of microorganisms containing Lactobacillus spp. (McPc) and assessed its effects on muscle strength and motor function in mice. Compared to unfermented Pc water extract, elevated levels of emodin and resveratrol were noted in McPc. This was identified and quantified using UPLC-QTOF/MS and HPLC techniques. Gene expression profiling through RNA-seq and quantitative RT-PCR revealed that McPc administration upregulated the expression of genes associated with antioxidants, glycolysis, oxidative phosphorylation, fatty acid oxidation, and mitochondrial biogenesis in cultured C2C12 myotubes and the gastrocnemius muscle in mice. McPc significantly improved skeletal muscle strength, motor coordination, and traction force in mice subjected to sciatic neurectomy and high-fat diet (HFD). McPc administration exhibited more pronounced improvement of obesity, hyperglycemia, fatty liver, and hyperlipidemia in HFD mice compared to control group. These findings support the notion that emodin and resveratrol-enriched McPc may offer health benefits for addressing skeletal muscle weakness.

The association between circulatory, local pancreatic PCSK9 and type 2 diabetes mellitus: The effects of antidiabetic drugs on PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent modulator of cholesterol metabolism and plays a crucial role in the normal functioning of pancreatic islets and the progression of diabetes. Islet autocrine PCSK9 deficiency can lead to the enrichment of low-density lipoprotein (LDL) receptor (LDLR) and excessive LDL cholesterol (LDL-C) uptake, subsequently impairing the insulin secretion in β-cells. Circulatory PCSK9 levels are primarily attributed to hepatocyte secretion. Notably, anti-PCSK9 strategies proposed for individuals with hypercholesterolemia chiefly target liver-derived PCSK9; however, these anti-PCSK9 strategies have been associated with the risk of new-onset diabetes mellitus (NODM). In the current review, we highlight a new direction in PCSK9 inhibition therapy strategies: screening candidates for anti-PCSK9 from the drugs used in type 2 diabetes mellitus (T2DM) treatment. We explored the association between circulating, local pancreatic PCSK9 and T2DM, as well as the relationship between PCSK9 monoclonal antibodies and NODM. We discussed the emergence of artificial and natural drugs in recent years, exhibiting dual benefits of antidiabetic activity and PCSK9 reduction, confirming that the diverse effects of these drugs may potentially impact the progression of diabetes and associated disorders, thereby introducing novel avenues and methodologies to enhance disease prognosis.

HM-chromanone isolated from Portulaca oleracea L. alleviates insulin resistance and inhibits gluconeogenesis by regulating palmitate-induced activation of ROS/JNK in HepG2 cells

Oxidative stress is a major cause of hepatic insulin resistance. This study investigated whether (E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone (HM-chromanone), a homoisoflavonoid compound isolated from Portulaca oleracea L., alleviates insulin resistance and inhibits gluconeogenesis by reducing palmitate (PA)-induced reactive oxygen species (ROS)/c-Jun NH2-terminal kinase (JNK) activation in HepG2 cells. PA treatment (0.5 mM) for 16 h resulted in the highest production of ROS and induced insulin resistance in HepG2 cells. HM-chromanone, like N-acetyl-1-cysteine, significantly decreased PA-induced ROS production in the cells. HM-chromanone also significantly inhibited PA-induced JNK activation, showing a significant reduction in tumor necrosis factor and interleukin expression levels. Thus, HM-chromanone decreased the phosphorylation of Ser307 in insulin receptor substrate 1, while increasing phosphorylation of serine-threonine kinase (AKT), thereby restoring the insulin signaling pathway impaired by PA. HM-chromanone also significantly increased the phosphorylation of forkhead box protein O, thereby inhibiting the expression of gluconeogenic enzymes and reducing glucose production in PA-treated HepG2 cells. HM-chromanone also increased glycogen synthesis by phosphorylating glycogen synthase kinase-3β. Therefore, HM-chromanone may alleviate insulin resistance and inhibit gluconeogenesis by regulating PA-induced ROS/JNK activation in HepG2 cells.

The therapeutic mechanism of Yuye decoction on type 2 diabetes mellitus based on network pharmacology and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Yuye decoction (YYD) has been widely used as a folk Chinese herbal formula in clinical treatment of type 2 diabetes mellitus(T2DM) for many years. However, its mechanism is still unclear.

AIM OF THE STUDY

The aim of this study was to explore the potential mechanism of YYD against T2DM initially by UHPLC-MS/MS combining with network pharmacology, molecular docking techniques and experimental validation.

MATERIALS AND METHODS

The main ingredients in the water extract of YYD were initially identified using UHPLC-MS/MS analysis. Combined with network pharmacology and molecular docking techniques, the YYD key compounds-core targets-key signaling pathways network was constructed and the binding activity of key components to core targets was validated. The T2DM rat model was induced by Streptozotocin combined with high glucose and high fat diets. The apoptosis cell model of mouse islet β-cell of Min6 was induced by high-glucose and palmitic acid. Histopathological and immunofluorescence satining were used to evaluate pancreatic islet β-cell function and apoptosis in rats. Min6 cell viability and apoptosis ratio were evaluated by CCK-8 and TUNEL staining. The predicted targets and pathways were validated by experiments in vitro and in vivo.

RESULTS

The 56 compounds from YYD were identified by UHPLC-MS/MS. The potential targets of the above compounds were predicted by online compound target database, among of which 362 targets were associated with T2DM. Protein-protein interaction analysis identified the main targets such as SRC, MAPK1, PIK3R1, AKT1, HRAS and HSP90AA1, which were considered as the therapeutic targets of YYD on against T2DM. Functional enrichment analysis revealed that PI3K/AKT, FoxO and apoptosis signaling pathways were significantly enriched. Molecular docking results showed that compounds of monolinolein, neomangiferin, mangiferin, pelargonidin-3-O-glucoside and acacetin from YYD had high binding activities to PIK3R1, AKT1, Sirt1 and FoxO1. Therefore, PI3K/AKT1, Sirt1/FoxO1 and apoptotic signaling pathways were considered as predicted targets for experimental validation study. Animal experiments showed that YYD reduced blood glucose levels, improved pancreatic dysfunction and pancreatic islet β-cells apoptosis in T2DM rats which contributed to the activation of AKT1 and FoxO1 and their related signaling molecules. These results were confirmed in Min6 cell model induced by high-glucose and palmitic acid.

CONCLUSIONS

In summary, this study systematically visualized the possible therapeutic effects and mechanisms of YYD on T2DM through the network pharmacology approach and experimental study. The results indicated that YYD could prevent pancreatic islet dysfunction and reverse islet of β-cells apoptosis possibly via PI3K/AKT1, Sirt1/FoxO1 signaling pathways.

Polydatin: Pharmacological Mechanisms, Therapeutic Targets, Biological Activities, and Health Benefits

Polydatin is a natural potent stilbenoid polyphenol and a resveratrol derivative with improved bioavailability. Polydatin possesses potential biological activities predominantly through the modulation of pivotal signaling pathways involved in inflammation, oxidative stress, and apoptosis. Various imperative biological activities have been suggested for polydatin towards promising therapeutic effects, including anticancer, cardioprotective, anti-diabetic, gastroprotective, hepatoprotective, neuroprotective, anti-microbial, as well as health-promoting roles on the renal system, the respiratory system, rheumatoid diseases, the skeletal system, and women's health. In the present study, the therapeutic targets, biological activities, pharmacological mechanisms, and health benefits of polydatin are reviewed to provide new insights to researchers. The need to develop further clinical trials and novel delivery systems of polydatin is also considered to reveal new insights to researchers.

Pharmacological effects of polydatin in the treatment of metabolic diseases: A review

BACKGROUND

Metabolic diseases (MDs), a series of chronic disorders, severely decreases the quality of life for patients but also cause a heavy economic burden. Emerging evidence suggests that Polydatin (PD), an important glucoside of resveratrol, is widely distributed in many plants and has shown good therapeutic potential in metabolic diseases.

PURPOSE

To review the PD discovered before 2021 and their potential to treat metabolic diseases. The activities against diabetes, Obesity, atherosclerosis, NAFLD, NASH, hyperlipidemia, and gout with special emphasis on pharmacology, pharmacokinetics, mechanisms of action, possible roles in current medicine, and future perspectives are discussed.

METHODS

A comprehensive search of published literature was conducted to locate original publications pertaining to polydatin and MDs through the end of 2021 using MEDLINE, Elsevier, Springer, PubMed, Scholar, and CNKI databases. The main inquiry used was for the presence of the following keywords in various combinations in the abstracts: 'Polydatin', 'Metabolic diseases', 'Pharmacology', 'Toxicology', 'Pharmacokinetics', 'Diabetes', 'Obesity', 'Atherosclerosis', 'Non-alcoholic fatty liver disease', 'Non-alcoholic steatohepatitis', 'Hyperlipidemia', and 'Gout'.

RESULTS

The search yielded 987 articles, of which 33 articles were included in this review. Studies have revealed that PD can promote insulin secretion, alleviate insulin resistance, regulate glucose and lipid metabolism, reduce liver lipid deposition, inhibit inflammation, oxidative stress, and decrease uric acid deposition in preclinical experiments. The underlying mechanisms of PD in treatment MDs may be attributed to the regulation of multiple signaling pathways, including. NF-κB, AGEs/RAGE, MAPK/ERK, AMPK/LDLR, IRS1/PI3K/AKT, LKB1/AMPK, PPARβ-NO, SIRT1-PGC-1α-SOD2, PKC, etc., The pharmacokinetic profiles of PD provide valuable information on therapeutic efficacy in treating metabolic diseases.

CONCLUSION

This review summarizes the available reports and evidence which support the use of PD as a potential candidate in the treatment of MDs and provides an overview of the modulatory effects of PD in metabolic diseases and cell signaling pathways, which may have important implications in its future clinical use.

Marantodes pumilum Var Alata (Kacip Fatimah) ameliorates derangement in RANK/RANKL/OPG pathway and reduces inflammation and oxidative stress in the bone of estrogen-deficient female rats with type-2 diabetes

BACKGROUND

M. pumilum has been claimed to protect the bone against the adverse effect of estrogen deficiency. Additionally, it also exhibits anti-diabetic activity. In view of these, this study aims to identify the mechanisms underlying the bone protective effect of M. pumilum in the presence of both estrogen deficiency and diabetes mellitus (DM).

METHODS

Ovariectomized, diabetic female rats were given M. pumilum leave aqueous extract (MPLA) (50 and 100 mg/kg/day), estrogen, glibenclamide and estrogen plus glibenclamide for 28 consecutive days. At the end of the treatment, fasting blood glucose (FBG), serum insulin, Ca²⁺, PO₄^3- and bone alkaline phosphatase (BALP) levels were measured. Rats were sacrificed and femur bones were harvested for determination of expression level and distribution of RANK, RANKL, OPG and oxidative stress and inflammatory proteins by molecular biological techniques.

RESULTS

100 mg/kg/day MPLA treatment decreased the FBG and BALP levels but increased the serum insulin, Ca²⁺ and PO₄^3- levels in estrogen deficient, diabetic rats. Expression and distribution of RANKL, NF-κB p65, IKKβ, IL-6, IL-1β and Keap-1 decreased however expression and distribution of RANK, OPG, BMP-2, Type-1 collagen, Runx2, TRAF6, Nrf2, NQO-1, HO-1, SOD and CAT increased in the bone of estrogen deficient, diabetic rats which received 100 mg/kg/day MPLA with greater effects than estrogen-only, glibenclamide-only and estrogen plus glibenclamide treatments.

CONCLUSION

MPLA helps to overcome the adverse effect of estrogen deficiency and DM on the bone and thus this herb could potentially be used for the treatment and prevention of osteoporosis in postmenopausal women with diabetes.

Quercetin and metabolic syndrome: A review

Metabolic syndrome (MetS) is a complex of diseases that lead to mortality due to the development of cardiovascular problems. Quercetin, as an important flavonoid, has various properties such as decreasing blood pressure, anti-hyperlipidemia, anti-hyperglycemia, anti-oxidant, antiviral, anticancer, anti-inflammatory, anti-microbial, neuroprotective, and cardio-protective effects. In this review article, we collected original articles from different sources such as Google Scholar, Medline, Scopus, and Pubmed, which is related to the effect of quercetin on the improvement of the signs of MetS, including elevated glucose level, hyperlipidemia, obesity, and blood pressure. According to these data, quercetin may also have a role in the management of metabolic disorders via different mechanisms such as increasing adiponectin, decreasing leptin, anti-oxidant activity, reduction of insulin resistance, the elevation of insulin level, and blocking of calcium channel. We have attempted to make some recommendations on the quercetin application in patients. However, it needs to do further clinical trials and more investigations to show the real clinical value of quercetin on metabolic syndrome.

Glucokinase activation as antidiabetic therapy: effect of nutraceuticals and phytochemicals on glucokinase gene expression and enzymatic activity

Diabetes represents an important public health problem. Recently, new molecular targets have been identified and exploited to treat this disease. Due to its pivotal role in glucose homeostasis, glucokinase (GCK) is a promising target for the development of novel antidiabetic drugs; however, pharmacological agents that modulate GCK activity have been linked to undesirable side-effects, limiting its use. Interestingly, plants might be a valuable source of new therapeutic compounds with GCK-activating properties and presumably no adverse effects. In this review, we describe biochemical characteristics related to the physiological and pathological importance of GCK, as well as the mechanisms involved in its regulation at different molecular levels. Posteriorly, we present a compendium of findings supporting the potential use of nutraceuticals and phytochemicals in the management of diabetes through modulation of GCK expression and activity. Finally, we propose critical aspects to keep in mind when designing experiments to evaluate GCK modulation properly.

Icaritin ameliorates hepatic steatosis via promoting fatty acid β-oxidation and insulin sensitivity

AIM

This study aimed to reveal the effects of icaritin (ICT) on lipotoxicity induced by palmitate (PA) in hepatic cells and steatosis in high-fat diet (HFD)-fed mice as well as exploring the potential mechanisms.

MAIN METHODS

Primary mouse hepatocytes and human hepatoma Huh7 cells were used to evaluate ICT effect in vitro. HFD-fed mice were used to evaluate the ICT effect in vivo.

RESULTS

In vitro study indicated that ICT significantly rescued PA-induced steatosis, mainly through a combination of robust increased mitochondrial respiration, fatty acid oxidation and mildly decreased synthesis of fatty acid. An HFD-fed mouse model with 8 weeks HFD-fed showed metabolic disorders, while ICT application significantly reduced the weight, serum glucose levels, insulin resistance, hepatic steatosis level and adipose contents. In consistent with the observations in cell lines, ICT rescued the HFD-impaired functions and contents of key factors related to fatty acid β-oxidation through elevated expression of peroxisome proliferator-activated receptor α (PPARα). Meanwhile, it also reversed the decreased phosphoryl levels of AKT and glucogen synthase kinase 3 (GSK3β), leading to the improvement of insulin resistance.

SIGNIFICANCE

ICT administration had a therapeutic effect on PA- or HFD-induced hepatic steatosis and metabolic disorders. It may provide a novel strategy to construct preventive and therapeutic means for hepatic steatosis.

Polydatin mitigates pancreatic β-cell damage through its antioxidant activity

Several reports have been shown the pivotal role of oxidative stress in the progression of diabetes mellitus and its complications. Polydatin (PD), a natural phytochemical, has wide range of pharmacological actions, however, the underlying beneficial effects in pancreas was not clarified. In the current study, using in vivo and in vitro models, we investigated the possible protective effects of PD against oxidative damage in pancreatic β-cells. Diabetic rats were examined after oral administration with PD (50 mg/kg b.wt.) for 28 days. Results revealed that PD significantly enhanced glucose tolerance and insulin secretion in the bloodstream of diabetic rats as well as lipid metabolism. Interestingly, in vivo results indicated that PD decreased the lipid peroxidation, improved the antioxidant status, and inhibited the inflammation in pancreas. Alongside, we artificially induced oxidative stress by exposing the insulin-producing RINm5F cells to hydrogen peroxide in the presence or absence of PD. The co-treatment with PD preserved cell viability, reduced ROS accumulation, as well as enhanced the anti-oxidant, anti-apoptotic, and cell function markers. To conclude, PD exhibited potential action in preserving β-cell function and inhibiting oxidative damage probably through its antioxidant properties. Thus, PD could be a possible therapeutic agent for diabetic patients.

Cardioprotective effects of polydatin against myocardial injury in diabetic rats via inhibition of NADPH oxidase and NF-κB activities

Background

Diabetic cardiomyopathy is a main cause of the increased morbidity in diabetic patients, no effective treatment is available so far. Polydatin, a resveratrol glucoside isolated from the Polygonum cuspidatum, was found by our and others have antioxidant and cardioprotective activities. Therapeutic effects of polydatin on diabetic cardiomyopathy and the possible mechanisms remains unclear. This study aimed to investigate the cardioprotective effects and underlying mechanisms of polydatin on myocardial injury induced by hyperglycemia.

Methods

Diabetes in rats was made by high-fat diet combined with multiple low doses of streptozotocin, and then treated with polydatin (100 mg·kg-1·day-1, by gavage) for 8 weeks. Cardiac function was examined by echocardiography. Myocardial tissue and blood samples were collected for histology, protein and metabolic characteristics analysis. In cultured H9c2 cells with 30 mM of glucose, the direct effects of polydatin on myocyte injury were also observed.

Results

In diabetic rats, polydatin administration significantly improved myocardial dysfunction and attenuated histological abnormalities, as evidenced by elevating left ventricular shortening fraction and ejection fraction, as well as reducing cardiac hypertrophy and interstitial fibrosis. In cultured H9c2 cells, pretreatment of polydatin dose-dependently inhibited high glucose-induced cardiomyocyte injury. Further observation evidenced that polydatin suppressed the increase in the reactive oxygen species levels, NADPH oxidase activity and inflammatory cytokines production induced by hyperglycemia in vivo and in vitro. Polydatin also prevented the increase expression of NOX4, NOX2 and NF-κB in the high glucose -stimulated H9c2 cells and diabetic hearts.

Conclusions

Our results demonstrate that the cardioprotective effect of polydatin against hyperglycemia-induced myocardial injury is mediated by inhibition of NADPH oxidase and NF-κB activity. The findings may provide a novel understanding the mechanisms of the polydatin to be a potential treatment of diabetic cardiomyopathy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-020-03177-y.

Polydatin attenuates renal fibrosis in diabetic mice through regulating the Cx32-Nox4 signaling pathway

We previously found that polydatin could attenuate renal oxidative stress in diabetic mice and improve renal fibrosis. Recent evidence shows that NADPH oxidase 4 (Nox4)-derived reactive oxygen species (ROS) contribute to inflammatory and fibrotic processes in diabetic kidneys. In this study we investigated whether polydatin attenuated renal fibrosis by regulating Nox4 in vitro and in vivo. In high glucose-treated rat glomerular mesangial cells, polydatin significantly decreased the protein levels of Nox4 by promoting its K48-linked polyubiquitination, thus inhibited the production of ROS, and eventually decreasing the expression of fibronectin (FN) and intercellular adhesion molecule-1 (ICAM-1), the main factors that exacerbate diabetic renal fibrosis. Overexpression of Nox4 abolished the inhibitory effects of polydatin on FN and ICAM-1 expression. In addition, the expression of Connexin32 (Cx32) was significantly decreased, which was restored by polydatin treatment. Cx32 interacted with Nox4 and reduced its protein levels. Knockdown of Cx32 abolished the inhibitory effects of polydatin on the expression of FN and ICAM-1. In the kidneys of streptozocin-induced diabetic mice, administration of polydatin (100 mg·kg-1·d-1, ig, 6 days a week for 12 weeks) increased Cx32 expression and reduced Nox4 expression, decreased renal oxidative stress levels and the expression of fibrotic factors, eventually attenuating renal injury and fibrosis. In conclusion, polydatin promotes K48-linked polyubiquitination and degradation of Nox4 by restoring Cx32 expression, thereby decreasing renal oxidative stress levels and ultimately ameliorating the pathological progress of diabetic renal fibrosis. Thus, polydatin reduces renal oxidative stress levels and attenuates diabetic renal fibrosis through regulating the Cx32-Nox4 signaling pathway.

An Update on the Emerging Role of Visfatin in the Pathogenesis of Osteoarthritis and Pharmacological Intervention

Osteoarthritis (OA) is one of the most common degenerative joint diseases that affects millions of people worldwide, mainly the aging population. Despite numerous published reports, little is known about the pathology of this disease, and no feasible treatment plan exists to stop OA progression. Recently, extensive basic and clinical studies have shown that adipokines play a key role in OA development. Moreover, some drugs associated with adipokines have shown chondroprotective and anti-inflammatory effects on OA. Visfatin has been shown to play a detrimental role in the progression of OA. It increases the production of matrix metalloproteinases and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), induces the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, affects the differentiation of mesenchymal stem cells to adipocytes, and induces osteophyte formation by inhibiting osteoclastogenesis. Although some side effects of chemical visfatin inhibitors have been reported, they were shown to be successful in the treatment of diabetes, cancer, and other diseases that can utilize Chinese herbs, further suggesting that similar therapeutic strategies could be used in OA prevention and treatment. Here, we describe the pathophysiological mechanism of visfatin in OA and discuss some potential pharmacological interventions using Chinese herbs.

Polydatin alleviates parkinsonism in MPTP-model mice by enhancing glycolysis in dopaminergic neurons

Parkinson's disease (PD) is a common neurodegenerative disease. Damage to energy metabolism and reduced adenosine triphosphate (ATP) levels in dopaminergic neurons are common features of PD. Previous studies suggested that the occurrence of PD often affects glucose metabolism and ATP production in the brain, and increased glycolysis or ATP production protects dopaminergic neuronal degeneration in the brain of PD patients. These systems may provide new potential therapeutic targets for the prevention of PD. The present study investigated the inhibitory action of polydatin (PLD) on early dopaminergic neuronal degeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The results showed that PLD protected against MPTP-induced early dopaminergic neuronal degeneration. PLD reduced the MPTP-induced loss of dopaminergic neurons in substantia nigra and striatum, inhibited the occurrence of neural apoptosis, and restored motor function in mice. PLD also increased the continuous activity duration and rhythm amplitude in mice during the circadian activity test. PLD improved glucose metabolism in the brain and restored ATP production levels. These observations suggest that PLD attenuates MPTP-induced early PD-like symptoms, and its mechanism of action may be associated with the promotion of glucose metabolism in neurons.

Polydatin for treating atherosclerotic diseases: A functional and mechanistic overview

With the advancement of science and technology, the living standards of human beings have continuously improved, but the incidence and mortality from atherosclerosis worldwide have also increased by year. Although interventional surgery and the continuous development of new drugs have significant therapeutic effects, their side effects cannot be ignored. Polydatin, an active ingredient isolated from the natural medicine Polygonum cuspidatum, has been shown to have a prominent role in the treatment of cardiovascular diseases. Polydatin treats atherosclerosis mainly from three aspects: anti-inflammatory, regulating lipid metabolism and anti-oxidative stress. This article will review the pharmacological mechanism of polydatin in anti-atherosclerosis, the biological characteristics of Polygonum cuspidatum, the toxicology and pharmacokinetics of polydatin and will provide ideas for further research.

Interplay between NADH oxidation by complex I, glutathione redox state and sirtuin-3, and its role in the development of insulin resistance

Metabolic diseases are characterized by high NADH/NAD⁺ ratios due to excessive electron supply, causing defective mitochondrial function and impaired sirtuin-3 (SIRT-3) activity, the latter driving to oxidative stress and altered fatty acid β-oxidation. NADH is oxidized by the complex I in the electron transport chain, thereby factors inhibiting complex I like acetylation, cardiolipin peroxidation, and glutathionylation by low GSH/GSSG ratios affects SIRT3 function by increasing the NADH/NAD⁺ ratio. In this review, we summarized the evidence supporting a role of the above events in the development of insulin resistance, which is relevant in the pathogenesis of obesity and diabetes. We propose that maintenance of proper NADH/NAD⁺ and GSH/GSSG ratios are central to ameliorate insulin resistance, as alterations in these redox couples lead to complex I dysfunction, disruption of SIRT-3 activity, ROS production and impaired β-oxidation, the latter two being key effectors of insulin resistance.

Beneficial effects of combination therapy of phloretin and metformin in streptozotocin-induced diabetic rats and improved insulin sensitivity in vitro

Phloretin combined with metformin ameliorates glucose and lipid metabolism in STZ-induced T2D rats via AKT/GLUT4 signaling pathways.

Novel polydatin-loaded chitosan nanoparticles for safe and efficient type 2 diabetes therapy: In silico, in vitro and in vivo approaches

Polydatin (PD) has many pharmacological activities; however, its bioavailability is still a critical cornerstone issue. The present investigation aimed to develop a novel oral formula of polydatin-loaded chitosan nanoparticles (PD-CSNPs) to improve PD therapeutic potential against type 2 diabetes. The interaction mechanism between PD and CSNPs was studied via Monte Carlo and molecular dynamics simulations. The formula was prepared and characterized by FTIR, XRD, TEM, and dynamic light scattering. The release profile of PD was studied in vitro, as well as the cytotoxicity effect versus Vero cell line and antidiabetic activity in type 2 diabetic rats were investigated. The practical results verified the formation of PD-CSNPs with entrapment efficiency of about 96.74 ± 0.39%, size average 144.25 ± 3.37 nm, and the prolonged release pattern was less than 20% after 12 hrs. The cytotoxicity study confirmed the safety of the formula at low and high doses. Moreover, the in vivo study revealed that PD-CSNPs exhibited highly significant antidiabetic efficacy in diabetic rats compared to free PD. To conclude, the current investigation proved that CSNPs are promising nanocarriers for nontoxic and effective PD delivery against type 2 diabetes.

Novel natural and synthetic inhibitors of solute carriers SGLT1 and SGLT2

Selective analogs of the natural glycoside phloridzin are marketed drugs that reduce hyperglycemia in diabetes by inhibiting the active sodium glucose cotransporter SGLT2 in the kidneys. In addition, intestinal SGLT1 is now recognized as a target for glycemic control. To expand available type 2 diabetes remedies, we aimed to find novel SGLT1 inhibitors beyond the chemical space of glycosides. We screened a bioactive compound library for SGLT1 inhibitors and tested primary hits and additional structurally similar molecules on SGLT1 and SGLT2 (SGLT1/2). Novel SGLT1/2 inhibitors were discovered in separate chemical clusters of natural and synthetic compounds. These have IC50-values in the 10-100 μmol/L range. The most potent identified novel inhibitors from different chemical clusters are (SGLT1-IC50 Mean ± SD, SGLT2-IC50 Mean ± SD): (+)-pteryxin (12 ± 2 μmol/L, 9 ± 4 μmol/L), (+)-ε-viniferin (58 ± 18 μmol/L, 110 μmol/L), quinidine (62 μmol/L, 56 μmol/L), cloperastine (9 ± 3 μmol/L, 9 ± 7 μmol/L), bepridil (10 ± 5 μmol/L, 14 ± 12 μmol/L), trihexyphenidyl (12 ± 1 μmol/L, 20 ± 13 μmol/L) and bupivacaine (23 ± 14 μmol/L, 43 ± 29 μmol/L). The discovered natural inhibitors may be further investigated as new potential (prophylactic) agents for controlling dietary glucose uptake. The new diverse structure activity data can provide a starting point for the optimization of novel SGLT1/2 inhibitors and support the development of virtual SGLT1/2 inhibitor screening models.

Therapeutic Mechanisms of Herbal Medicines Against Insulin Resistance: A Review

Insulin resistance is a condition in which insulin sensitivity is reduced and the insulin signaling pathway is impaired. Although often expressed as an increase in insulin concentration, the disease is characterized by a decrease in insulin action. This increased workload of the pancreas and the consequent decompensation are not only the main mechanisms for the development of type 2 diabetes (T2D), but also exacerbate the damage of metabolic diseases, including obesity, nonalcoholic fatty liver disease, polycystic ovary syndrome, metabolic syndrome, and others. Many clinical trials have suggested the potential role of herbs in the treatment of insulin resistance, although most of the clinical trials included in this review have certain flaws and bias risks in their methodological design, including the generation of randomization, the concealment of allocation, blinding, and inadequate reporting of sample size estimates. These studies involve not only the single-flavored herbs, but also herbal formulas, extracts, and active ingredients. Numerous of in vitro and in vivo studies have pointed out that the role of herbal medicine in improving insulin resistance is related to interventions in various aspects of the insulin signaling pathway. The targets involved in these studies include insulin receptor substrate, phosphatidylinositol 3-kinase, glucose transporter, AMP-activated protein kinase, glycogen synthase kinase 3, mitogen-activated protein kinases, c-Jun-N-terminal kinase, nuclear factor-kappaB, protein tyrosine phosphatase 1B, nuclear factor-E2-related factor 2, and peroxisome proliferator-activated receptors. Improved insulin sensitivity upon treatment with herbal medicine provides considerable prospects for treating insulin resistance. This article reviews studies of the target mechanisms of herbal treatments for insulin resistance.

PAQR3 regulates phosphorylation of FoxO1 in insulin-resistant HepG2 cells via NF-κB signaling pathway

Insulin resistance is a significant feature of type 2 diabetes mellitus and glucose and lipid metabolism disorders. Activation of NF-κB signaling pathway plays an important role in the formation of insulin resistance. FoxO1 plays a major role in regulating glucose and lipid metabolism, as well as insulin signaling pathway. Previous studies have shown that Progestin and AdipoQ Receptor 3 (PAQR3) suppresses the activity of PI3K/Akt, which is an upstream pathway of FoxO1, and additionally promotes the pathological process of diabetic renal inflammatory fibrosis via activating NF-κB pathway. On this basis, it has caused us great concern whether NF-κB is involved in PAQR3 regulation of FoxO1 under insulin resistance. In this study, we aimed to investigate whether PAQR3 regulates phosphorylation of FoxO1 via NF-κB pathway in palmitic acid (PA)-induced insulin-resistant HepG2 cells, thereby causing glucose and lipid metabolism disorders. We found that PA stimulation and PAQR3 overexpression decreased the phosphorylation of FoxO1 and the expressions of glucokinase (GCK) and low density lipoprotein receptor (LDLR), in addition, promoted the nuclear accumulation of NF-κB. Inhibition of NF-κB pathway increased the phosphorylation of FoxO1 and the expressions of GCK and LDLR which were downregulated by PA stimulation and PAQR3 overexpression. Taken together, in PA-induced insulin-resistant HepG2 cells, PAQR3 might regulate the phosphorylation of FoxO1 and the expressions of GCK and LDLR through NF-κB pathway, thereby regulating the glucose and lipid metabolism disorders induced by insulin resistance.

Paeonol Ameliorates Glucose and Lipid Metabolism in Experimental Diabetes by Activating Akt

Our previous study proved that paeonol (Pae) could lower blood glucose levels of diabetic mice. There are also a few reports of its potential use for diabetes treatment. However, the role of Pae in regulating glucose and lipid metabolism in diabetes remains largely unknown. Considering the critical role of serine/threonine kinase B (Akt) in glucose and lipid metabolism, we explored whether Pae could improve glucose and lipid metabolism disorders via Akt. Here, we found that Pae attenuated fasting blood glucose, glycosylated serum protein, serum cholesterol and triglyceride (TG), hepatic glycogen, cholesterol and TG in diabetic mice. Moreover, Pae enhanced glucokinase (GCK) and low-density lipoprotein receptor (LDLR) protein expressions, and increased the phosphorylation of Akt. In insulin-resistant HepG2 cells, Pae increased glucose uptake and decreased lipid accumulation. What’s more, Pae elevated LDLR and GCK expressions as well as Akt phosphorylation, which was consistent with the in vivo results. Knockdown and inhibition experiments of Akt revealed that Pae regulated LDLR and GCK expressions through activation of Akt. Finally, molecular docking assay indicated the steady hydrogen bond was formed between Pae and Akt2. Experiments above suggested that Pae ameliorated glucose and lipid metabolism disorders and the underlying mechanism was closely related to the activation of Akt.

Metabolic regulation of T cell development by Sin1-mTORC2 is mediated by pyruvate kinase M2

Glucose metabolism plays a key role in thymocyte development. The mammalian target of rapamycin complex 2 (mTORC2) is a critical regulator of cell growth and metabolism, but its role in early thymocyte development and metabolism has not been fully studied. We show here that genetic ablation of Sin1, an essential component of mTORC2, in T lineage cells results in severely impaired thymocyte development at the CD4-CD8- double negative (DN) stages but not at the CD4+CD8+ double positive (DP) or later stages. Notably, Sin1-deficient DN thymocytes show markedly reduced proliferation and glycolysis. Importantly, we discover that the M2 isoform of pyruvate kinase (PKM2) is a novel and crucial Sin1 effector in promoting DN thymocyte development and metabolism. At the molecular level, we show that Sin1-mTORC2 controls PKM2 expression through an AKT-dependent PPAR-γ nuclear translocation. Together, our study unravels a novel mTORC2-PPAR-γ-PKM2 pathway in immune-metabolic regulation of early thymocyte development.

Polydatin Attenuates Atherosclerosis in ApoE -∕- Mice through PBEF Mediated Reduction of Cholesterol Deposition

Cholesterol metabolism becomes imbalanced during the formation of macrophage-derived foam cells. Pre-B-cell colony-enhancing factor (PBEF) has recently been found to affect lipid deposition and inflammation in atherosclerosis. Here, we aimed to study the effects and molecular mechanism of Polydatin on atherosclerosis in ApoE-knockout (ApoE -∕- ) mice. Thirty ApoE -∕- mice were fed a high-fat diet (HFD) for 12 weeks, and then treated with Polydatin for another 12 weeks. Whole aortas and cryosections were stained with oil red O. Blood lipid, PBEF and cytokine levels were measured by ELISA. The mRNAs of cholesterol metabolism-related genes were determined by qRT-PCR and protein levels by Western blotting. Cell cholesterol content and viability were determined in macrophages and RAW 264.7 cells. PBEF siRNA was used to study the effect of Polydatin on cholesterol metabolism in macrophages incubated with ox-LDL. Polydatin lowered blood lipids and decreased atherosclerotic lesions in ApoE -∕- mice. The expression of cytokines and the mRNA of cholesterol metabolism-related genes were markedly regulated by Polydatin. Meanwhile, PBEF mRNA and protein were both greatly down-regulated by Polydatin. In vitro, Polydatin protected RAW 264.7 cells treated by ox-LDL and inhibited cholesterol uptake by macrophages. The PBEF siRNA result indicates that Polydatin can modulate cholesterol metabolism in macrophages, partly through down-regulation of PBEF. In conclusion, Polydatin relieves atherosclerosis injury in ApoE -∕- mice, mainly through down-regulation of PBEF and inhibition of PBEF-inducing cholesterol deposits in macrophages.

Small molecules as inhibitors of PCSK9: Current status and future challenges

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in regulating lipoprotein metabolism by binding to low-density lipoprotein receptors (LDLRs), leading to their degradation. LDL cholesterol (LDL-C) lowering drugs that operate through the inhibition of PCSK9 are being pursued for the management of hypercholesterolemia and reducing its associated atherosclerotic cardiovascular disease (CVD) risk. Two PCSK9-blocking monoclonal antibodies (mAbs), alirocumab and evolocumab, were approved in 2015. However, the high costs of PCSK9 antibody drugs impede their prior authorization practices and reduce their long-term adherence. Given the potential of small-molecule drugs, the development of small-molecule PCSK9 inhibitors has attracted considerable attention. This article provides an overview of the recent development of small-molecule PCSK9 inhibitors disclosed in the literature and patent applications, and different approaches that have been pursued to modulate the functional activity of PCSK9 using small molecules are described. Challenges and potential strategies in developing small-molecule PCSK9 inhibitors are also discussed.

Resveratrol, Metabolic Syndrome, and Gut Microbiota

Resveratrol is a polyphenol which has been shown to have beneficial effects on metabolic syndrome-related alterations in experimental animals, including glucose and lipid homeostasis improvement and a reduction in fat mass, blood pressure, low-grade inflammation, and oxidative stress. Clinical trials have been carried out to address its potential; however, results are still inconclusive. Even though resveratrol is partly metabolized by gut microbiota, the relevance of this “forgotten organ” had not been widely considered. However, in the past few years, data has emerged suggesting that the therapeutic potential of this compound may be due to its interaction with gut microbiota, reporting changes in bacterial composition associated with beneficial metabolic outcomes. Even though data is still scarce and for the most part observational, it is promising nevertheless, suggesting that resveratrol supplementation could be a useful tool for the treatment of metabolic syndrome and its associated conditions.

Metabolic switching in the hypoglycemic and antitumor effects of metformin on high glucose induced HepG2 cells

Metformin, a widely prescribed drug for the management of type 2 diabetes mellitus, has potential anticancer effect. Diabetes patients regularly taking metformin have been reported with decreased cancer risk and improved cancer prognosis in recent years. A cell model of high glucose induced HepG2 cells was conducted to mimic insulin resistance, and a ¹H NMR-based metabolomics approach in conjunction with molecular biology was performed to investigate the metabolic changes of high glucose induced HepG2 cells in response to different doses of metformin treatment and to study the differences and links between hypoglycemic and antitumor effects of metformin. Metformin with hypoglycemic effect rectified glucose metabolic imbalance and regulated oxidative stress, energy and amino acid metabolism. Metformin inhibited tumor cell proliferation and induced apoptosis through activation of AMPK/mTOR pathway and further influencing energy metabolism, phospholipid metabolism and glucose catabolism. The integrated metabolomics approach showed its potential in clarifying the different action on metformin treatment and understanding the pleiotropic effect of metformin.

Natural products for the treatment of type 2 diabetes mellitus: Pharmacology and mechanisms

Epidemiological studies have implied that diabetes mellitus (DM) will become an epidemic accompany with metabolic and endocrine disorders worldwide. Most of DM patients are affected by type 2 diabetes mellitus (T2DM) with insulin resistance and insulin secretion defect. Generally, the strategies to treat T2DM are diet control, moderate exercise, hypoglycemic and lipid-lowing agents. Despite the therapeutic benefits for the treatment of T2DM, most of the drugs can produce some undesirable side effects. Considering the pathogenesis of T2DM, natural products (NPs) have become the important resources of bioactive agents for anti-T2DM drug discovery. Recently, more and more natural components have been elucidated to possess anti-T2DM properties, and many efforts have been carried out to elucidate the possible mechanisms. The aim of this paper was to overview the activities and underlying mechanisms of NPs against T2DM. Developments of anti-T2DM agents will be greatly promoted with the increasing comprehensions of NPs for their multiple regulating effects on various targets and signal pathways.

The Aqueous Extract of Gynura divaricata (L.) DC. Improves Glucose and Lipid Metabolism and Ameliorates Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by hyperglycemia and dyslipidemia caused by impaired insulin secretion and resistance of the peripheral tissues. A major pathogenesis of T2DM is obesity-associated insulin resistance. Gynura divaricata (L.) DC. (GD) is a natural plant and has been reported to have numerous health-promoting effects on both animals and humans. In this study, we aimed to elucidate the regulatory mechanism of GD improving glucose and lipid metabolism in an obesity animal model induced by high-fat and high-sugar diet in combination with low dose of streptozocin and an insulin-resistant HepG2 cell model induced by dexamethasone. The study showed that the water extract of GD (GD extract A) could significantly reduce fasting serum glucose, reverse dyslipidemia and pancreatic damage, and regulate the body weight of mice. We also found that GD extract A had low toxicity in vivo and in vitro. Furthermore, GD extract A may increase glucose consumption in insulin-resistant HepG2 cells, markedly inhibit NF-κB activation, and decrease the impairment in signaling molecules of insulin pathway, such as IRS-1, AKT, and GLUT1. Overall, the results indicate that GD extract A is a promising candidate for the prevention and treatment of T2DM.

Increased glucose metabolism and alpha-glucosidase inhibition in Cordyceps militaris water extract-treated HepG2 cells

BACKGROUND/OBJECTIVES

Recent living condition improvements, changes in dietary habits, and reductions in physical activity are contributing to an increase in metabolic syndrome symptoms including diabetes and obesity. Through such societal developments, humankind is continuously exposed to metabolic diseases such as diabetes, and the number of the victims is increasing. This study investigated Cordyceps militaris water extract (CMW)-induced glucose uptake in HepG2 cells and the effect of CMW treatment on glucose metabolism.

MATERIALS/METHODS

Colorimetric assay kits were used to determine the glucokinase (GK) and pyruvate dehydrogenase (PDH) activities, glucose uptake, and glycogen content. Either RT-PCR or western blot analysis was performed for quantitation of glucose transporter 2 (GLUT2), hepatocyte nuclear factor 1 alpha (HNF-1α), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phosphorylated AMP-activated protein kinase (pAMPK), phosphoenolpyruvate carboxykinase, GK, PDH, and glycogen synthase kinase 3 beta (GSK-3β) expression levels. The α-glucosidase inhibitory activities of acarbose and CMW were evaluated by absorbance measurement.

RESULTS

CMW induced glucose uptake in HepG2 cells by increasing GLUT2 through HNF-1α expression stimulation. Glucose in the cells increased the CMW-induced phosphorylation of AMPK. In turn, glycolysis was stimulated, and glyconeogenesis was inhibited. Furthermore, by studying the mechanism of action of PI3k, Akt, and GSK-3β, and measuring glycogen content, the study confirmed that the glucose was stored in the liver as glycogen. Finally, CMW resulted in a higher level of α-glucosidase inhibitory activity than that from acarbose.

CONCLUSION

CMW induced the uptake of glucose into HepG2 cells, as well, it induced metabolism of the absorbed glucose. It is concluded that CMW is a candidate or potential use in diabetes prevention and treatment.

Thymol improves high-fat diet-induced cognitive deficits in mice via ameliorating brain insulin resistance and upregulating NRF2/HO-1 pathway

The impaired insulin signaling has been recognized as a common pathogenetic mechanism between diabetes and Alzheimer's disease (AD). In the progression of AD, brain is characterized by defective insulin receptor substrate-1 (IRS-1) and increased oxidative stress. Thymol, a monoterpene phenol isolated from medicinal herbs, has exhibited robust neuroprotective effects. The present study was designed to investigate the protective effect of thymol on HFD-induced cognitive deficits, and explore the possible mechanisms. C57BL/6 J mice were fed for 12 weeks with either HFD or normal diet. The mice fed with HFD were dosed with metformin (200 mg/kg) or thymol (20, 40 mg/kg) daily. It was observed that thymol treatment significantly reversed the gain of body weight and peripheral insulin resistance induced by HFD. Meanwhile, thymol improved the cognitive impairments in the Morris Water Maze (MWM) test and decreased HFD-induced Aβ deposition and tau hyperphosphorylation in the hippocampus, which may be correlated with the inhibition of hippocampal oxidative stress and inflammation. In addition, thymol down-regulated the level of P-Ser307 IRS-1, and hence enhancing the expression of P-Ser473 AKT and P-Ser9 GSK3β. We further found that the protective effects of thymol on cognitive impairments were associated with the up-regulation of nuclear respiratory factor (Nrf2)/heme oxygenase-1(HO-1) pathway. In conclusion, thymol exhibited beneficial effects on HFD-induced cognitive deficits through improving hippocampal insulin resistance, and activating Nrf2/HO-1 signaling.

Regulation of PCSK9 by nutraceuticals

PCSK9 (proprotein convertase subtilisin kexin type 9) is a liver secretory enzyme that regulates plasma low-density lipoprotein (LDL) cholesterol (LDL-C) levels through modulation of LDL receptor (LDLR) density on the surface of hepatocytes. Inhibition of PCSK9 using monoclonal antibodies can efficiently lower plasma LDL-C, non-high-density lipoprotein cholesterol and lipoprotein (a). PCSK9 inhibition is also an effective adjunct to statin therapy; however, the cost-effectiveness of currently available PCSK9 inhibitors is under question. Nutraceuticals offer a safe and cost-effective option for PCSK9 inhibition. Several nutraceuticals have been reported to modulate PCSK9 levels and exert LDL-lowering activity. Mechanistically, those nutraceuticals that inhibit PCSK9 through a SREBP (sterol-responsive element binding protein)-independent pathway can be more effective in lowering plasma LDL-C levels compared with those inhibiting PCSK9 through the SREBP pathway. The present review aims to collect available data on the nutraceuticals with PCSK9-inhibitory effect and the underlying mechanisms.

Phloretin exerts hypoglycemic effect in streptozotocin-induced diabetic rats and improves insulin resistance in vitro

The present study investigated the possible antiobesity and hypoglycemic effects of phloretin (Ph). In an attempt to discover the hypoglycemic effect and potential mechanism of Ph, we used the streptozotocin-induced diabetic rats and (L6) myotubes. Daily oral treatment with Ph for 4 weeks significantly (P<0.05) reduced postprandial blood glucose and improved islet injury and lipid metabolism. Glucose consumption and glucose tolerance were improved by Ph via GOD–POD method. Western blot results revealed that the expression of Akt, PI3K, IRS-1, and GLUT4 were upregulated in skeletal muscle of type 2 diabetes (T2D) rats and in L6 myotubes by Ph. The immunofluorescence studies confirmed that Ph improved the translocation of GLUT4 in L6 myotubes. Ph exerted hypoglycemic effects in vivo and in vitro, hence it may play an important role in the management of diabetes.

Quercetin Improves Glucose and Lipid Metabolism of Diabetic Rats: Involvement of Akt Signaling and SIRT1

Glucose and lipid metabolism disorder in diabetes mellitus often causes damage to multiple tissues and organs. Diabetes mellitus is beneficially affected by quercetin. However, its concrete mechanisms are yet to be fully elucidated. In our study, diabetes was induced in Sprague-Dawley rats by STZ injection. The rats were randomly divided into normal control, diabetic model, low-dose quercetin treatment, high-dose quercetin treatment, and pioglitazone treatment groups. Fasting blood glucose was collected to evaluate diabetes. Immunohistochemistry and fluorometric assay were performed to explore SIRT1. Akt levels were measured through immunoprecipitation and Western blot. After 12 weeks of quercetin treatment, the biochemical parameters of glucose and lipid metabolism improved to varying degrees. Hepatic histomorphological injury was alleviated, and hepatic glycogen content was increased. The expression and activity of hepatic SIRT1 were enhanced, and Akt was activated by phosphorylation and deacetylation. These results suggested that the beneficial effects of quercetin on glucose and lipid metabolism disorder are probably associated with the upregulated activity and protein level of SIRT1 and its influence on Akt signaling pathway. Hence, quercetin shows potential for the treatment of glucose and lipid metabolism disorder in diabetes mellitus.

Enzymatic Synthesis of Sorboyl-Polydatin Prodrug in Biomass-Derived 2-Methyltetrahydrofuran and Antiradical Activity of the Unsaturated Acylated Derivatives

Efficient and highly regioselective synthesis of the potential 6′′-O-sorboyl-polydatin prodrug in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was achieved using Candida antarctica lipase B for the first time. Under the optimal conditions, the initial reaction rate, maximum substrate conversion, and 6′′-regioselectivity were as high as 8.65 mM/h, 100%, and 100%, respectively. Kinetic and operational stability investigations evidently demonstrated excellent enzyme compatibility of the 2-MeTHF compared to the traditional organic solvents. With respect to the antioxidant properties, three unsaturated ester derivatives showed slightly lower DPPH radical scavenging activities than the parent agent. Interestingly, further studies also revealed that the antiradical capacities of the acylates decreased with the elongation of the unsaturated aliphatic chain length from C4 to C11. The reason might be attributed to the increased steric hindrance derived from the acyl residues in derivatives.

CKIP-1 ameliorates high glucose-induced expression of fibronectin and intercellular cell adhesion molecule-1 by activating the Nrf2/ARE pathway in glomerular mesangial cells

Glucose and lipid metabolism disorders as well as oxidative stress (OSS) play important roles in diabetic nephropathy (DN). Glucose and lipid metabolic dysfunctions are the basic pathological changes of chronic microvascular complications of diabetes mellitus, such as DN. OSS can lead to the accumulation of extracellular matrix and inflammatory factors which will accelerate the progress of DN. Casein kinase 2 interacting protein-1 (CKIP-1) mediates adipogenesis, cell proliferation and inflammation under many circumstances. However, whether CKIP-1 is involved in the development of DN remains unknown. Here, we show that CKIP-1 is a novel regulator of resisting the development of DN and the underlying molecular mechanism is related to activating the nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) antioxidative stress pathway. The following findings were obtained: (1) The treatment of glomerular mesangial cells (GMCs) with high glucose (HG) decreased CKIP-1 levels in a time-dependent manner; (2) CKIP-1 overexpression dramatically reduced fibronectin (FN) and intercellular adhesionmolecule-1 (ICAM-1) expression. Depletion of CKIP-1 further induced the production of FN and ICAM-1; (3) CKIP-1 promoted the nuclear accumulation, DNA binding, and transcriptional activity of Nrf2. Moreover, CKIP-1 upregulated the expression of Nrf2 downstream genes, heme oxygenase (HO-1) and superoxide dismutase 1 (SOD1); and ultimately decreased the levels of reactive oxygen species (ROS). The molecular mechanisms clarify that the advantageous effect of CKIP-1 on DN are well connected with the activation of the Nrf2/ARE antioxidative stress pathway.

Metabonomics applied in exploring the antitumour mechanism of physapubenolide on hepatocellular carcinoma cells by targeting glycolysis through the Akt-p53 pathway

Metabolomics can be used to identify potential markers and discover new targets for future therapeutic interventions. Here, we developed a novel application of the metabonomics method based on gas chromatography-mass spectrometry (GC/MS) analysis and principal component analysis (PCA) for rapidly exploring the anticancer mechanism of physapubenolide (PB), a cytotoxic withanolide isolated from Physalis species. PB inhibited the proliferation of hepatocellular carcinoma cells in vitro and in vivo, accompanied by apoptosis-related biochemical events, including the cleavage of caspase-3/7/9 and PARP. Metabolic profiling analysis revealed that PB disturbed the metabolic pattern and significantly decreased lactate production. This suggests that the suppression of glycolysis plays an important role in the anti-tumour effects induced by PB, which is further supported by the decreased expression of glycolysis-related genes and proteins. Furthermore, the increased level of p53 and decreased expression of p-Akt were observed, and the attenuated glycolysis and enhanced apoptosis were reversed in the presence of Akt cDNA or p53 siRNA. These results confirm that PB exhibits anti-cancer activities through the Akt-p53 pathway. Our study not only reports for the first time the anti-tumour mechanism of PB, but also suggests that PB is a promising therapeutic agent for use in cancer treatments and that metabolomic approaches provide a new strategy to effectively explore the molecular mechanisms of promising anticancer compounds.

Polydatin ameliorates lipid and glucose metabolism in type 2 diabetes mellitus by downregulating proprotein convertase subtilisin/kexin type 9 (PCSK9)

BACKGROUND

Abnormalities in lipid and glucose metabolism are constantly observed in type 2 diabetes. However, these abnormalities can be ameliorated by polydatin. Considering the important role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in metabolic diseases, we explore the possible mechanism of polydatin on lipid and glucose metabolism through its effects on PCSK9.

METHODS

An insulin-resistant HepG2 cell model induced by palmitic acid (PA) and a db/db mice model were used to clarify the role of polydatin on lipid and glucose metabolism.

RESULTS

In insulin-resistant HepG2 cells, polydatin upregulated the protein levels of LDLR and GCK but repressed PCSK9 protein expression, besides, polydatin also inhibited the combination between PCSK9 and LDLR. Knockdown and overexpression experiments indicated that polydatin regulated LDLR and GCK expressions through PCSK9. In the db/db mice model, we found that polydatin markedly enhanced GCK and LDLR protein levels, and inhibited PCSK9 expression in the liver. Molecular docking assay was further performed to analyze the possible binding mode between polydatin and the PCSK9 crystal structure (PDB code: 2p4e), which indicated that steady hydrogen bonds formed between polydatin and PCSK9.

CONCLUSIONS

Our study indicates that polydatin ameliorates lipid and glucose metabolism in type 2 diabetes mellitus by downregulating PCSK9.

Selective separation and identification of metabolite groups of Polygonum cuspidatum extract in rat plasma using dispersion solid-phase extraction by magnetic molecularly imprinted polymers coupled with LC/Q-TOF-MS

In this work, magnetic molecularly imprinted polymers (MMIPs) were successfully prepared for specific recognition and selective enrichment of metabolite groups of Polygonum cuspidatum extract in rat plasma.

A metabolomics approach to studying the effects of Jinxin oral liquid on RSV-infected mice using UPLC/LTQ-Orbitrap mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Jinxin oral liquid (JOL) is a traditional Chinese medicine (TCM) formula modified from ma-xing-shi-gan-tang, an ancient formula widely used in the treatment of respiratory diseases such as bronchitis, pneumonia, and asthma. In our previous studies, JOL was shown to safely and effectively treat viral pneumonia, especially that involving respiratory syncytial virus (RSV).

AIM OF THE STUDY

To investigate the mechanism of the effect of JOL in RSV infected mice, using a metabolomics approach based on ultra-performance liquid chromatography coupled with linear ion trap quadrupole-Orbitrap mass spectrometry (UPLC/LTQ-Orbitrap-MS).

MATERIALS AND METHODS

BALB/c mice were divided into four groups, the control group (saline inoculation/no treatment), RSV group (RSV inoculation/saline treatment), RSV+JOL group (RSV inoculation/JOL treatment), and RSV+Riba group (RSV inoculation/ribavirin treatment). Plasma and lung tissue samples were collected 7 days after the inoculation/treatment protocols, and UPLC/LTQ-Orbitrap-MS method based on metabolomics was developed. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were utilized to identify biomarkers potentially associated with the anti-RSV activity of JOL.

RESULTS

JOL was associated with reduced inflammatory responses in RSV-infected lung tissue. The combination of PCA and OPLS-DA revealed deviations in 11 biomarkers in plasma, and 16 biomarkers in lung tissue induced by RSV that were corrected with JOL treatment. These biomarkers were primarily components of metabolic pathways involving glycerophosphocholines, sphingolipids, and glycerolipids. JOL was able to restore the abnormal levels of these biomarkers detected in the plasma and lung tissue of RSV-infected mice to approximately normal levels.

CONCLUSIONS

This study suggested that JOL can treat RSV pneumonia effectively, partially by ameliorating the associated disturbances to lipid metabolism. The results provided insight into the anti-RSV mechanism of JOL, and also demonstrated that metabolomics is a valuable tool for investigating the efficacy of TCM treatment for RSV pneumonia, and the associated biomarkers involved.