Isoquercitrin activates the AMP-activated protein kinase (AMPK) signal pathway in rat H4IIE cells

Traditional Chinese medicine and plant-derived natural products in regulating triglyceride metabolism: Mechanisms and therapeutic potential

The incidence of cardiometabolic disease is increasing globally, with a trend toward younger age of onset. Among these, atherosclerotic cardiovascular disease is a leading cause of mortality worldwide. Despite the efficacy of traditional lipid-lowering drugs, such as statins, in reducing low-density lipoprotein cholesterol levels, a significant residual risk of cardiovascular events remains, which is closely related to unmet triglyceride (TG) targets. The clinical application of current TG-lowering Western medicines has certain limitations, necessitating alternative or complementary therapeutic strategies. Traditional Chinese medicine (TCM) and plant-derived natural products, known for their safety owing to their natural origins and diverse biological activities, offer promising avenues for TG regulation with potentially fewer side effects. This review systematically summarises the mechanisms of TG metabolism and subsequently reviews the regulatory effects of TCM and plant-derived natural products on TG metabolism, including the inhibition of TG synthesis (via endogenous and exogenous pathways), promotion of TG catabolism, regulation of fatty acid absorption and transport, enhancement of lipophagy, modulation of the gut microbiota, and other mechanisms. In conclusion, through a comprehensive analysis of recent studies, this review consolidates the multifaceted regulatory roles of TCM and plant-derived natural products in TG metabolism and elucidates their potential as safer, multi-target therapeutic agents in managing hypertriglyceridemia and mitigating cardiovascular risk, thereby providing a basis for new drug development.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Effect of Isoquercitrin on Free Fatty Acid-Induced Lipid Accumulation in HepG2 Cells

Liver metabolic disorders and oxidative stress are crucial factors in the development of nonalcoholic fatty liver disease (NAFLD); however, treatment strategies to combat NAFLD remain poorly established, presenting an important challenge that needs to be addressed. Herein, we aimed to examine the effect of isoquercitrin on lipid accumulation induced by exogenous free fatty acids (FFA) using HepG2 cells and elucidate the underlying molecular mechanism. The cells were exposed to 0.5 mM FFA to induce intracellular lipid accumulation, followed by co-treatment with isoquercitrin to confirm the potential inhibitory effect on FFA-induced lipid production. HepG2 cells exposed to FFA alone exhibited intracellular lipid accumulation, compromised endoplasmic reticulum (ER) stress, and enhanced expression of proteins and genes involved in lipid synthesis; however, co-treatment with isoquercitrin decreased the expression of these molecules in a dose-dependent manner. Furthermore, isoquercitrin could activate AMP-activated protein kinase (AMPK), a key regulatory protein of hepatic fatty acid oxidation, suppressing new lipid production by phosphorylating acetyl-CoA carboxylase (ACC) and inhibiting sterol regulatory element-binding transcription factor 1 (SREBP-1)/fatty acid synthase (FAS) signals. Overall, these findings suggest that isoquercitrin can be employed as a therapeutic agent to improve NAFLD via the regulation of lipid metabolism by targeting the AMPK/ACC and SREBP1/FAS pathways.

Effect of quercetin and Abelmoschus esculentus (L.) Moench on lipids metabolism and blood glucose through AMPK-α in diabetic rats (HFD/STZ)

Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme in the glyconeogenesis pathway. The AMP-activated protein kinase alpha (AMPK-α) pathway regulates PEPCK, which itself is activated by the AMP/ATP ratio and liver kinase B1 (KB1). The Abelmoschus esculentus (L.) Moench (okra) plant contains a large amount of quercetin that can function as an agonist or an antagonist. The aim of this study was to examine the effects of quercetin flavonoid and A. esculentus extract on the level of AMPK-α expression and associated metabolic pathways. The findings demonstrate that metformin, quercetin, and okra extract may significantly raise AMPK-α levels while significantly lowering PEPCK and hormone-sensitive lipase (HSL) levels, in addition to improving glucose and lipid profiles. By stimulating KB1, these substances increased AMPK-α activation. Additionally, AMPK-α activation improved insulin resistance and Glucose transporter type 4 (GLUT4) gene expression levels. Since AMPK-α maintains energy balance and its activity has not been reported to be inhibited so far, it could be a potent therapeutic target. PRACTICAL APPLICATIONS: The development of effective AMPK-α agonists and antagonists holds promise for the treatment of metabolic disorders like diabetes. Dietary polyphenols are a valuable source for developing new drugs. However, due to the lack of understanding of the underlying mechanisms of their effect on cells, their use in the treatment of diabetes is controversial. In addition to chemicals that have medicinal benefits, chemists are searching for less harmful substances. Using plants containing bioactive chemicals for this purpose can be a good alternative to chemical drugs.

Hawk tea prevents high-fat diet-induced obesity in mice by activating the AMPK/ACC/SREBP1c signaling pathways and regulating the gut microbiota

Scope: Hawk tea, a non-Camellia tea, is an ancient tea drink from southwest China and has been proven to exhibit significant hypoglycaemic and lipid-lowering effects. The aim of this study was to evaluate whether Hawk tea extract (HTE) can improve obesity induced by a high-fat diet (HFD) in a mouse model and to determine whether its anti-obesity effects are related to improvements in lipid metabolism and the gut microbiota. Methods and results: We tested the ability of HTE to prevent obesity and regulate gut microbiota in C57BL/6J mice fed with a HFD. We found that HTE significantly reduced body weight, fat deposition, serum triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels, and significantly increased serum levels of high-density lipoprotein cholesterol (HDL-C) induced by HFD. HTE also increased the levels of AMPK and ACC phosphorylation, up-regulated the expression of CPT-1, and downregulated the expression of SREBP1c and FAS. In addition, the administration of HTE significantly altered the composition of the gut microbiota, reduced the ratio of Firmicutes to Bacteroidetes, increased the relative abundance of Akkermansia muciniphila, Bacteroides-vulgatus, and Faecalibaculum_rodentium, and decreased the relative abundance of Desulfovibrionaceae and Lachnospiraceae. Conclusions: Collectively, our data demonstrate that HTE can prevent HFD-induced obesity by regulating the AMPK/ACC/SREBP1c signaling pathways and the gut microbiota.

Antioxidative effect of dietary flavonoid isoquercitrin on human ovarian granulosa cells HGL5 in vitro

This study aimed to examine the effect of dietary flavonoid isoquercitrin on ovarian granulosa cells using the immortalized human cell line HGL5. Cell viability, survival, apoptosis, release of steroid hormones 17beta-estradiol and progesterone, and human transforming growth factor-beta2 (TGF-beta2) and TGF-beta2 receptor as well as intracellular reactive oxygen species (ROS) generation were investigated after isoquercitrin treatment at the concentration range of 5-100 microg.ml-1. It did not cause any significant change (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. No significant change was observed (p>0.05) in the proportion of live, dead and apoptotic cells as revealed by apoptotic assay using flow cytometry. Similarly, the release of 17beta-estradiol, progesterone, TGF-beta2 and its receptor were not affected significantly (p>0.05) by isoquercitrin as detected by ELISA, in comparison to control. Except for the highest concentration of 100 microg.ml-1, which led to oxidative stress, isoquercitrin exhibited antioxidative activity at lower concentration used in the study (5, 10, 25, and 50 microg.ml-1) by hampering the production of intracellular ROS, in comparison to control, as detected by chemiluminescence assay (p<0.05). Findings of the present study indicate an existence of the antioxidative pathway that involves inhibition of intracellular ROS generation by isoquercitrin in human ovarian granulosa cells.

Diabetes Mellitus and Cardiovascular Diseases: Nutraceutical Interventions Related to Caloric Restriction

Type 2 diabetes (T2DM) and cardiovascular disease (CVD) are closely associated and represent a key public health problem worldwide. An excess of adipose tissue, NAFLD, and gut dysbiosis establish a vicious circle that leads to chronic inflammation and oxidative stress. Caloric restriction (CR) is the most promising nutritional approach capable of improving cardiometabolic health. However, adherence to CR represents a barrier to patients and is the primary cause of therapeutic failure. To overcome this problem, many different nutraceutical strategies have been designed. Based on several data that have shown that CR action is mediated by AMPK/SIRT1 activation, several nutraceutical compounds capable of activating AMPK/SIRT1 signaling have been identified. In this review, we summarize recent data on the possible role of berberine, resveratrol, quercetin, and L-carnitine as CR-related nutrients. Additionally, we discuss the limitations related to the use of these nutrients in the management of T2DM and CVD.

Screening of hypolipidemic active components in Jiang-Zhi-Ning and its preliminary mechanism research based on "active contribution value" study

ETHNOPHARMACOLOGICAL RELEVANCE

Jiang-Zhi-Ning (JZN) is a traditional Chinese medicine formula, which has the effect of lowering blood lipid level and softening blood vessels. It is clinically used in the treatment of hyperlipidemia with significant curative effect.

AIM OF THE STUDY

This study aims to screen the active components of JZN that are responsible for its blood lipids lowering effect and lay the foundation for elucidating pharmacodynamic material basis of the hypolipidemic effect of the formula.

MATERIALS AND METHODS

The hyperlipidemia model was used to evaluate the efficacy of the JZN effective extraction with the TC and TG of rat plasma as evaluation index. Then the established ultra-high performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry (UPLC-ESI-Q-TOF-MSn) method was utilized to analyze the components of JZN effective extraction and the absorbed components in rat plasma, the potential active components were screened by using the combined analysis results of in vivo and in vitro component identification. Then an established ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QqQ-MSn) method was used to determine the content of potential active components and its natural ratio in JZN effective extraction, and a potential active components combination (PACC) was formed accordingly. Then a HepG2 cell hyperlipidemia model induced by sodium oleate was used to study the hypolipidemic activity of PACC by detecting the content of TG level in the model. Meanwhile, the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to conduct preliminary research on its hypolipidemic mechanism. Then combined with the concept of "combination index" in the "median-effect principle", to calculate the half inhibitory concentration (IC50) values of PACC and each monomer component on inhibiting the TG level in the cell model. Subsequently, the "activity contribution study" was carried out, and the components with the sum of the "activity contribution value" of 85% were finally selected as the hypolipidemic active components of JZN.

RESULTS

The pharmacodynamics results showed that JZN effective extraction has displayed a good hypolipidemic effect. 45 components were identified in vitro, 108 components were identified from rat plasma, and 17 potential active components were screened out. The content determination result showed that the ratio of each potential active components in PACC as following: cassiaside C: rubrofusarin-6-O-gentiobioside: aurantio-obtusin-6-O-glucoside: hyperoside: isoquercitrin: quercetin-3-O-glucuronide: (E)-2,3,5,4'-tetrahydroxystilbene-2-O-glucoside: rutin: emodin-8-O-glucoside: astragalin: armepavine: N-nornuciferine: coclaurine: O-nornuciferine: nuciferine: N-norarmepavine: higenamine = 3.30: 16.06: 9.15: 23.94: 98.40: 417.45: 189.68: 8.62: 1.28: 5: 3.51: 14.57: 1.06: 1.35: 1: 5.64: 6.06, and the activity study results showed that it has displayed a good hypolipidemic activity. Finally, the hypolipidemic active components screened out by the "activity contribution study" were: quercetin-3-O-glucuronide, (E)-2,3,5,4'-tetrahydroxystilbene-2-O-glucoside, isoquercitrin, O-nornuciferine, hyperoside and rubrofusarin-6-O-gentiobioside.

CONCLUSIONS

A scientific and rational approach of screening the hypolipidemic active ingredients of JZN has been developed in the current study. In addition, the research revealed the blood lipid lowering mechanism of those ingredients, which provide a solid basis for further elucidating the hypolipidemic pharmacodynamic material basis and action mechanism of JZN.

Isoquercetin Improves Inflammatory Response in Rats Following Ischemic Stroke

Inflammatory response contributes to brain injury after ischemia and reperfusion (I/R). Our previous literature has shown isoquercetin plays an important role in protecting against cerebral I/R injury. The present study was conducted to further investigate the effect of isoquercetin on inflammation-induced neuronal injury in I/R rats with the involvement of cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and inhibitor of NF-κB (I-κB)/nuclear factor-kappa B (NF-κB) signaling pathway mediated by Toll-like receptor 4 (TLR4) and C5a receptor 1 (C5aR1). In vivo middle cerebral artery occlusion and reperfusion (MCAO/R) rat model and in vitro oxygen-glucose deprivation and reperfusion (OGD/R) neuron model were used. MCAO/R induced neurological deficits, cell apoptosis, and release of cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in ischemic brain in rats. Simultaneously, the expression of TLR4 and C5aR1 was significantly up-regulated in both MCAO/R rats and OGD/R neurons, accompanied with the inhibition of cAMP/PKA signaling and activation of I-κB/NF-κB signaling in the cortex of MCAO/R rats. Over-expression of C5aR1 in neurons induced decrease of cell viability, exerting similar effects with OGD/R injury. Isoquercetin acted as a neuroprotective agent against I/R brain injury to suppress inflammatory response and improve cell recovery by inhibiting TLR4 and C5aR1 expression, promoting cAMP/PKA activation, and inhibiting I-κB/NF-κB activation and Caspase 3 expression. TLR4 and C5aR1 contributed to inflammation and apoptosis via activating cAMP/PKA/I-κB/NF-κB signaling during cerebral I/R, suggesting that this signaling pathway may be a potent therapeutic target in ischemic stroke. Isoquercetin was identified as a neuroprotective agent, which maybe a promising therapeutic agent used for the treatment of ischemic stroke and related diseases.

Isolation and characterization of a glycosyltransferase with specific catalytic activity towards flavonoids from Tripterygium wilfordii

Flavonoids are important secondary metabolites that exist in many medicinal plants. Flavonoid glycosyltransferases can transfer sugar moieties to their parent rings, producing various flavonoid glycosides with significant pharmacological activities. Here, we report the molecular cloning of the O-glycosyltransferase TwUGT2 from Tripterygium wilfordii and its catalytic activity was explored by heterologous expression in E. coli. The results showed that TwUGT2 has specific glycosyltransferase activity towards C-3 and 7 hydroxyl groups of flavonoids, thereby converting quercetin and pinocembrin into isoquercitrin and pinocembrin 7-O-beta-D-glucoside, respectively. The identification of TwUGT2 will provide a useful molecular tool for synthetic biology and contribute to drug discovery.[Formula: see text].

The Protective Effects of Acer okamotoanum and Isoquercitrin on Obesity and Amyloidosis in a Mouse Model

Obesity increases risk of Alzheimer's Disease (AD). A high fat diet (HFD) can lead to amyloidosis and amyloid beta (Aβ) accumulation, which are hallmarks of AD. In this study, protective effects of the ethyl acetate fraction of Acer okamotoanum (EAO) and isoquercitrin were evaluated on obesity and amyloidosis in the HFD- and Aβ-induced mouse model. To induce obesity and AD by HFD and Aβ, mice were provided with HFD for 10 weeks and were intracerebroventricularly injected with Aβ_25-35. For four weeks, 100 and 10 mg/kg/day of EAO and isoquercitrin, respectively, were administered orally. Administration of EAO and isoquercitrin significantly decreased body weight in HFD and Aβ-injected mice. Additionally, EAO- and isoquercitrin-administered groups attenuated abnormal adipokines release via a decrease in leptin and an increase in adiponectin levels compared with the control group. Furthermore, HFD and Aβ-injected mice had damaged liver tissues, but EAO- and isoquercitrin-administered groups attenuated liver damage. Moreover, administration of EAO and isoquercitrin groups down-regulated amyloidosis-related proteins in the brain such as β-secretase, presenilin (PS)-1 and PS-2 compared with HFD and Aβ-injected mice. This study indicated that EAO and isoquercitrin attenuated HFD and Aβ-induced obesity and amyloidosis, suggesting that they could be effective in preventing and treating both obesity and AD.

Quercetin and Isoquercitrin Inhibiting Hepatic Gluconeogenesis Through LKB1-AMPKα Pathway

Objective

To observe the impact of quercetin and isoquercitrin on gluconeogenesis in hepatocytes.

Methods

Mouse primary hepatocytes were cultured with lactic acid and pyruvic acid. After treatment with quercetin and isoquercitrin for 24 hours, the glucose concentration in the culture supernatant was determined. RT-PCR was used to detect the mRNAs of PEPCK, G6Pase, LKB1, and AMPKα. Protein levels of LKB1, AMPKα, and Thr172 phosphorylation were evaluated by Western blot.

Results

The glucose concentration in the gluconeogenesis group (GN) was significantly higher than in the control group (C), but the glucose concentrations in the high level quercetin(group 80Q) and high level isoquercitrin (group 80I) were significantly lower than in the group GN, P<0.01. In the group 80Q, and group 80I, the mRNA levels of PEPCK and LKB1were significantly lower than in the group GN (P<0.01), and the G6Pase mRNA were significantly lower than in the group GN (P<0.05). The protein levels of LKB1 and the phosphorylation of AMPKα Thr172 in the group 80Q, group 40I, and group 80I were higher than in the group GN. The effects of quercetin and isoquercitrin on LKB1 and AMPKα were similar to those of metformin.

Conclusions

Quercetin and isoquercitrin inhibit gluconeogenesis in hepatocytes, which may be related to the LKB1 upregulation and phosphorylation of AMPKα.

Isoquercitrin Attenuated Cardiac Dysfunction Via AMPKα-Dependent Pathways in LPS-Treated Mice

SCOPE

Isoquercitrin (IQC) has been reported to play a protective role in many pathological conditions. Here, the effects of IQC on lipopolysaccharide (LPS)-induced cardiac dysfunction are investigated, exploring its potential molecular mechanisms.

METHODS AND RESULTS

C57BL/6 mice or H9c2 cardiomyoblasts are subjected to LPS challenge for 12 h. Pretreatment with IQC attenuates LPS-induced cardiac dysfunction. IQC remarkably reduces LPS-mediated inflammatory responses by inhibiting the mRNA levels of TNF-α, IL6, and MCP1 as well as the protein levels of p-IKKβ, p-IκBα, and p-p65 in vivo and in vitro. Interestingly, IQC administration also improves energy deficiencies caused by LPS, manifesting as significant increases in cardiac and cellular ATP levels. Furthermore, ATP levels increase due to the upregulation of PGC1β and PPAR-α, which enhances fatty acid oxidation in vivo and in vitro. However, the protective roles of IQC against LPS-mediated increased inflammatory responses and decreased acid fatty oxidation are partially blunted by inhibiting AMPKα in vitro, and suppressing AMPKα partially blocks the increased cardiac function elicited by IQC in LPS-treated mice.

CONCLUSION

IQC attenuates LPS-induced cardiac dysfunction by inhibiting inflammatory responses and by enhancing fatty acid oxidation, partially by activating AMPKα. IQC might be a potential drug for sepsis-induced cardiac dysfunction.

Isoquercitrin, ingredients in Tetrastigma hemsleyanum Diels et Gilg, inhibits hepatocyte growth factor/scatter factor-induced tumor cell migration and invasion

Aberrant activation of hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, Met, is involved in the development and progression of many human cancers. In the screening assay of extracts from the root tuber of Tetrastigma hemsleyanum Diels et Gilg, isoquercitrin inhibited HGF/SF-Met signaling as indicated by its inhibitory activity on HGF/SF-induced cell scattering. Further analysis revealed that isoquercitrin specifically inhibited HGF/SF-induced tyrosine phosphorylation of Met. We also found that isoquercitrin decreased HGF-induced migration and invasion by parental or HGF/SF-transfected bladder carcinoma cell line NBT-II cells. Furthermore, isoquercitrin inhibited HGF/SF-induced epithelial mesenchymal transition in vitro and the invasion/metastasis of HGF/SF-transfected NBT-II cells in vivo. Our data suggest the possible use of isoquercitrin in human cancers associated with dysregulated HGF/SF-Met signaling.

Effect of Morinda citrifolia (Noni)-Enriched Diet on Hepatic Heat Shock Protein and Lipid Metabolism-Related Genes in Heat Stressed Broiler Chickens

Heat stress (HS) has been reported to alter fat deposition in broilers, however the underlying molecular mechanisms are not well-defined. The objectives of the current study were, therefore: (1) to determine the effects of acute (2 h) and chronic (3 weeks) HS on the expression of key molecular signatures involved in hepatic lipogenic and lipolytic programs, and (2) to assess if diet supplementation with dried Noni medicinal plant (0.2% of the diet) modulates these effects. Broilers (480 males, 1 d) were randomly assigned to 12 environmental chambers, subjected to two environmental conditions (heat stress, HS, 35°C vs. thermoneutral condition, TN, 24°C) and fed two diets (control vs. Noni) in a 2 × 2 factorial design. Feed intake and body weights were recorded, and blood and liver samples were collected at 2 h and 3 weeks post-heat exposure. HS depressed feed intake, reduced body weight, and up regulated the hepatic expression of heat shock protein HSP60, HSP70, HSP90 as well as key lipogenic proteins (fatty acid synthase, FASN; acetyl co-A carboxylase alpha, ACCα and ATP citrate lyase, ACLY). HS down regulated the hepatic expression of lipoprotein lipase (LPL) and hepatic triacylglycerol lipase (LIPC), but up-regulated ATGL. Although it did not affect growth performance, Noni supplementation regulated the hepatic expression of lipogenic proteins in a time- and gene-specific manner. Prior to HS, Noni increased ACLY and FASN in the acute and chronic experimental conditions, respectively. During acute HS, Noni increased ACCα, but reduced FASN and ACLY expression. Under chronic HS, Noni up regulated ACCα and FASN but it down regulated ACLY. In vitro studies, using chicken hepatocyte cell lines, showed that HS down-regulated the expression of ACCα, FASN, and ACLY. Treatment with quercetin, one bioactive ingredient in Noni, up-regulated the expression of ACCα, FASN, and ACLY under TN conditions, but it appeared to down-regulate ACCα and increase ACLY levels under HS exposure. In conclusion, our findings indicate that HS induces hepatic lipogenesis in chickens and this effect is probably mediated via HSPs. The modulation of hepatic HSP expression suggest also that Noni might be involved in modulating the stress response in chicken liver.

Hepatoprotective potential of isoquercitrin against type 2 diabetes-induced hepatic injury in rats

Non-alcoholic fatty liver disease is a main complication of type 2 diabetes. Isoquercitrin are employed for antidiabetic therapies, but the effects on liver function and the hepatocytes are unclear. The aim of this study was to investigate the effects of isoquercitrin on the T2DM-induced hepatic injury in rats. Isoquercitrin (10 mg/kg/d, 30 mg/kg/d), sitagliptin phosphate (10 mg/kg/d) was given orally for 21 days. The administration of isoquercitrin at 10 mg/kg/d and 30 mg/kg/d showed a dose dependent. Compare to the negative control (treated with saline), rats medicated with isoquercitrin (30 mg/kg/d) and sitagliptin phosphate (10 mg/kg/d) improved the clinical symptoms, FBG and glucose tolerance, reduced serum ALT, AST and IR, but increased TP, Alb, SOD, GSH, MDA, HDL-C, INS and GLP-1. On histology, Rats of these to groups presented nearly normal liver tissue and Langerhans, degeneration, necrosis and apoptosis were markedly reduced. Instead, hepatocytes showed regenerate. These two groups also showed significant increase in mRNA expression of PKA, AKT, PKCa, InsR and PI3K, and a decrease in DPP-IV mRNA level. These results indicated that treatment with isoquercitrin protects against hepatic injury by T2DM.

Isoquercetin activates the ERK1/2-Nrf2 pathway and protects against cerebral ischemia-reperfusion injury in vivo and in vitro

Isoquercetin has exhibited a wide range of therapeutic properties, including antioxidant, anti-inflammatory and anti-allergic activities. The aim of the present study was to investigate the effect of isoquercetin on rats with 2 h middle cerebral artery occlusion (MCAO) and evaluate the neuroprotective effect of isoquercetin on a primary culture of rat hippocampal neuronal cells subjected to oxygen-glucose deprivation followed by reoxygenation (OGD/R). In vivo, the rats treated with isoquercetin exhibited a lower degree of neurological dysfunction and smaller infarct volume than the vehicle-treated rats. In vitro, it was found that isoquercetin prevented the OGD/R-induced increase in apoptosis, lactate dehydrogenase release and reduction in cell viability. Additionally, isoquercetin induced the upregulation of nuclear factor erythroid 2-related factor 2 gene and protein expression, and increased extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation. This indicates that the ERK1/2 pathway may contribute to the neuroprotective effect of isoquercetin against OGD/R-induced oxidative damage in rat hippocampal neurons. These findings suggest the potential importance of isoquercetin in the treatment of ischemia/reperfusion-related brain injury and associated diseases.

Purification of Flavonoids from Chinese Bayberry (Morella rubra Sieb. et Zucc.) Fruit Extracts and α-Glucosidase Inhibitory Activities of Different Fractionations

Chinese bayberry (Morella rubra Sieb. et Zucc.) fruit have a diverse flavonoid composition responsible for the various medicinal activities, including anti-diabetes. In the present study, efficient simultaneous purification of four flavonoid glycosides, i.e., cyanidin-3-O-glucoside (1), myricetin-3-O-rhamnoside (2), quercetin-3-O-galactoside (3), quercetin-3-O-rhamnoside (4), from Chinese bayberry pulp was established by the combination of solid phase extract (SPE) by C18 Sep-Pak^® cartridge column chromatography and semi-preparative HPLC (Prep-HPLC), which was followed by HPLC and LC-MS identification. The purified flavonoid glycosides, as well as different fractions of fruit extracts of six bayberry cultivars, were investigated for α-glucosidase inhibitory activities. The flavonol extracts (50% methanol elution fraction) of six cultivars showed strong α-glucosidase inhibitory activities (IC₅₀ = 15.4–69.5 μg/mL), which were higher than that of positive control acarbose (IC₅₀ = 383.2 μg/mL). Four purified compounds 1–4 exerted α-glucosidase inhibitory activities, with IC₅₀ values of 1444.3 μg/mL, 418.8 μg/mL, 556.4 μg/mL, and 491.8 μg/mL, respectively. Such results may provide important evidence for the potential anti-diabetic activity of different cultivars of Chinese bayberry fruit and the possible bioactive compounds involved.

Regulation of AMP-activated protein kinase by natural and synthetic activators

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells. While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner, during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level, by responding to hormones that act primarily on the hypothalamus. AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP, and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed. Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans, such as type 2 diabetes, cancer and inflammatory disorders, there has been a major drive to develop pharmacological activators of AMPK. Many such activators have been described, and the various mechanisms by which these activate AMPK will be discussed. A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines. While the mechanism by which most of these activate AMPK has not yet been addressed, I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores, and that many of them will turn out to be inhibitors of mitochondrial function.

Salicornia herbacea prevents weight gain and hepatic lipid accumulation in obese ICR mice fed a high-fat diet

BACKGROUND

Foods that are rich in fat and or sodium chloride promote obesity and associated diseases, whereas intake of dietary fiber averts obesity development. Salicornia herbacea (SH) is a rich source of dietary fiber and high in sodium chloride; therefore, we investigated whether replacing common salt with SH in a high-fat diet could prevent obesity development.

RESULTS

Mice were divided into five groups: group ND was fed a normal diet, group HD was fed a high-fat diet, group HD-NaCl was fed a high fat diet with sodium chloride 10 g kg(-1) , group HD-CL was fed a high-fat diet with cellulose 30 g kg(-1) and group HD-SH was fed a high-fat diet with SH powder 50 g kg(-1) . The amount of sodium chloride and cellulose added in the respective diet was equivalent to their amount in SH. Data from our study showed that, SH supplementation significantly decreased body weight gain, liver weight, hepatic triglyceride, serum leptin and insulin, along with the mRNA level of key lipid anabolic genes such as SREBP-1c, PPARγ and FAS compared to the HD group.

CONCLUSION

The results of this study demonstrated that SH is a potential natural anti-obesity agent that can be used in place of sodium chloride.