Vomifoliol 9-O-α-arabinofuranosyl (1→6)-β-D-glucopyranoside from the leaves of Diospyros Kaki stimulates the glucose uptake in HepG2 and 3T3-L1 cells

A Review: Pharmacological Effect of Natural Compounds in Diospyros kaki Leaves from the Perspective of Oxidative Stress

Oxidative stress is caused by an imbalance between reactive oxygen species and antioxidant levels. Current research suggests that oxidative stress is one of the key factors in the development of many chronic diseases, and it has been a concern for many years. Many natural compounds have been studied for their special free-radical-scavenging properties. The major chemical constituents of the leaves of Diospyros kaki are flavonoids and triterpenoids, both of which are potential antioxidants that can prevent damage caused by reactive oxygen species or reactive nitrogen species and ameliorate diseases associated with oxidative stress. In addition to the major constituents such as flavonoids and triterpenoids, the leaves of Diospyros kaki include compounds such as phenylpropanoids, alkaloids, phenolic acids, and terpenes. Studies have shown these compounds have certain antioxidant and neuroprotective activities. Experiments have shown that flavonoids or the extracts from the leaves of Diospyros kaki have a variety of good pharmacological activities, which could activate oxidative stress and mitochondrial apoptosis, inhibit the proliferation of human prostate cancer cells and induce apoptosis. It also could achieve the effect of anti-cancer cell proliferation and induce apoptosis by regulating oxidative stress. The main chemical substance of the leaves of Diospyros kaki regulating oxidative stress may be these multi-hydroxyl structure compounds. These natural products exhibit significant antioxidant activity and are an important basis for the leaves of Diospyros kaki to treat human diseases by regulating oxidative stress. This review summarizes the structural types of natural products in the leaves of Diospyros kaki and elaborates the mechanism of the leaves of Diospyros kaki in neuroprotection, anti-diabetes, renal protection, retinal degenerative diseases, and anti-cancer from a new perspective of oxidative stress, including how it supplements other pharmacological effects. The chemical constituents and pharmacological effects of the leaves of Diospyros kaki are summarized in this paper. The relationship between the chemical components in the leaves of Diospyros kaki and their pharmacological effects is summarized from the perspective of oxidative stress. This review provides a reference for the study of natural anti-oxidative stress drugs.

Flavonoid compound from Agrimonia pilosa Ledeb improves adipose insulin resistance by alleviating oxidative stress and inflammation

BACKGROUND

Researches and practice of traditional Chinese medicine indicated that Agrimonia pilosa Ledeb could improve insulin resistance (IR) and treat type 2 diabetes (T2DM). To reveal its underling mechanisms, we isolated Flavonoid component (FC) from Agrimonia pilosa Ledeb and elucidated its effects on glucose metabolism to improve IR by suppressing oxidative stress and inflammation.

METHODS

Adipocytes or mice IR model was established with overdosed glucose and insulin or high-fat diet. The uptake of 2-NBDG and glucose consumption were measured to verify insulin sensitivity in vitro and vivo. Reactive oxidative species (ROS) were detected by flow cytometry, and superoxide dismutase (SOD) activity as well as the malondialdehyde (MDA) content were also measured. Meanwhile, factors associated with insulin signal pathway including PPARγ, insulin receptor substrate-1 (IRS-1), GLUT4, and oxidative stress including NF-E2-related factor 2 (Nrf2), as well as the related inflammatory cytokines such as NF-κB, IL-1β, IL-6 and TNF-α were tested. Furthermore, the JNK/PI3K/Akt signal pathway was also explored.

RESULTS

FC extracted from Agrimonia pilosa Ledeb ameliorated the impaired glucose metabolism significantly. Further study indicated that FC could regulate the insulin signal pathway to improve insulin resistance. Moreover, it could upregulate PPARγ with the similar efficacy as pioglitazone (Piog) straightway. FC also decreased the endogenous ROS and MDA content, increased SOD activity and Nrf2 expression to facilitate oxidative homeostasis. It attenuated expression and secretion of inflammatory cytokines obviously. At last, our results indicated JNK/PI3K/Akt pathway was regulated by FC in adipocytes and adipose tissue.

CONCLUSION

FC could ameliorate glucose metabolism and improve IR. It exerted these effects by suppressing oxidative stress and inflammation. FC from Agrimonia pilosa Ledeb has a good prospect to be drugs or functional foods for IR and T2DM.

An integrative analysis to predict the active compounds and explore polypharmacological mechanisms of Orthosiphon stamineus Benth

BACKGROUND

Orthosiphon stamineus Benth is a dietary supplement and traditional Chinese herb with widespread clinical applications, but a comprehensive understanding of its active compounds and polypharmacological mechanisms is lacking. This study aimed to systematically investigate the natural compounds and molecular mechanisms of O. stamineus via network pharmacology.

METHODS

Information on compounds from O. stamineus was collected via literature retrieval, while physicochemical properties and drug-likeness were evaluated using SwissADME. Protein targets were screened using SwissTargetPrediction, while the compound-target networks were constructed and analyzed via Cytoscape with CytoHubba for seed compounds and core targets. Enrichment analysis and disease ontology analysis were then carried out, generating target-function and compound-target-disease networks to intuitively explore potential pharmacological mechanisms. Lastly, the relationship between active compounds and targets was confirmed via molecular docking and dynamics simulation.

RESULTS

A total of 22 key active compounds and 65 targets were identified and the main polypharmacological mechanisms of O. stamineus were addressed. The molecular docking results suggested that nearly all core compounds and their targets possess good binding affinity. In addition, the separation of receptor and ligands was not observed in all dynamics simulation processes, whereas complexes of orthosiphol Z-AR and Y-AR performed best in simulations of molecular dynamics.

CONCLUSION

This study successfully identified the polypharmacological mechanisms of the main compounds in O. stamineus, and predicted five seed compounds along with 10 core targets. Moreover, orthosiphol Z, orthosiphol Y, and their derivatives can be utilized as lead compounds for further research and development. The findings here provide improved guidance for subsequent experiments, and we identified potential active compounds for drug discovery or health promotion.

Persimmon Leaves: Nutritional, Pharmaceutical, and Industrial Potential-A Review

Persimmon is a delicious fruit, and its leaves are considered a valuable ingredient in food, beverage, pharmaceutical, and cosmetic sectors. Traditionally, persimmon leaves (PL) are used as a functional tea in Asian culture to cure different ailments, and are also incorporated into various food and cosmeceutical products as a functional ingredient. PL mainly contain flavonoids, terpenoids, and polysaccharides, along with other constituents such as carotenoids, organic acids, chlorophylls, vitamin C, and minerals. The major phenolic compounds in PL are proanthocyanidins, quercetin, isoquercetin, catechin, flavonol glucosides, and kaempferol. Meanwhile, ursolic acid, rotungenic acid, barbinervic acid, and uvaol are the principal terpenoids. These compounds demonstrate a wide range of pharmacological activities, including antioxidant, anticancer, antihypertensive, antidiabetic, anti-obesity, anti-tyrosinase, antiallergic, and antiglaucoma properties. This review summarizes the latest information on PL, mainly distribution, traditional uses, industrial potential, and bioactive compounds, as well as their potential action mechanisms in exhibiting biological activities. In addition, the effect of seasonality and geographical locations on the content and function of these biomolecules are discussed.

A Narrative Review of Human Clinical Trials on the Impact of Phenolic-Rich Plant Extracts on Prediabetes and Its Subgroups

Phenolic-rich plant extracts have been demonstrated to improve glycemic control in individuals with prediabetes. However, there is increasing evidence that people with prediabetes are not a homogeneous group but exhibit different glycemic profiles leading to the existence of prediabetes subgroups. Prediabetes subgroups have been identified as: isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), and combined impaired fasting glucose and glucose intolerance (IFG/IGT). The present review investigates human clinical trials examining the hypoglycemic potential of phenolic-rich plant extracts in prediabetes and prediabetes subgroups. Artemisia princeps Pampanini, soy (Glycine max (L.) Merrill) leaf and Citrus junos Tanaka peel have been demonstrated to improve fasting glycemia and thus may be more useful for individuals with IFG with increasing hepatic insulin resistance. In contrast, white mulberry (Morus alba Linn.) leaf, persimmon (Diospyros kaki) leaf and Acacia. Mearnsii bark were shown to improve postprandial glycemia and hence may be preferably beneficial for individuals with IGT with increasing muscle insulin resistance. Elaeis guineensis leaf was observed to improve both fasting and postprandial glycemic measures depending on the dose. Current evidence remains scarce regarding the impact of the plant extracts on glycemic control in prediabetes subgroups and therefore warrants further study.

Chemical Constituents of the Leaves of Diospyros kaki (Persimmon)

Diospyros kaki (persimmon) leaves have long been utilized as traditional medicine for the treatment of ischemic stroke, angina, and hypertension and as a healthy beverage and cosmetic for anti-aging. This study aimed to isolate as many compounds as possible from an ethanol extract of the persimmon leaves to identify the biologically active compounds. The antioxidative effect of the ethyl acetate layer from the ethanol extract of the persimmon leaves was demonstrated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and online high-performance liquid chromatography-2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (HPLC-ABTS) analysis. A new flavonoid, kaempferol-3-O-β-d-2″-coumaroylgalactoside (1), and a new natural compound, kaempferol-3-O-β-d-2″-feruloylglucoside (3) were isolated from the ethyl acetate layer, along with 25 previously known compounds, including fourteen flavonoids, one ionone, two coumarins, seven triterpenoids, and one acetophenone. Their structures were determined by the interpretation of spectrometric and spectroscopic data. All isolated compounds were rapidly evaluated using an online HPLC-ABTS assay, and of these, compounds 4–8, 11, 13, 15, and 16 clearly showed antioxidative effects. The amount of these compounds was 0.3–0.65% of the extract.

Nephroprotective effect of persimmon leaves (Diospyros kaki L.f.) against CCl4-induced renal toxicity in Swiss Albino rats

Diospyros kaki L.f. fruit and leaves are traditionally used for the treatment of hypertension, angina, internal hemorrhage, antithrombotic and anti-inflammatory effects.In the current study, the protective effects of ethyl acetate (Per-1), n-butanol (Per-2), and aqueous (Per-3) fractions of Diospyros kaki leaves against carbon tetrachloride (CCl₄) induced nephrotoxicity in Swiss albino rats were tested. Animal were divided into nine groups; each group consists of six animals. The groups were : group I was untreated and kept as control, group II was treated with CCl₄ only, group III (silymarin with CCl₄); group IV (Per-1 100 mg/kg with CCl₄);group V (Per-1 200 mg/kg with CCl₄); group VI (Per-2 100 mg/kg with CCl₄); group VII (Per-2 200 mg/kg with CCl₄); group VIII (Per-3 100 mg/kg with CCl₄); and group IX (Per-3 200 mg/kg with CCl₄). Silymarin was used as standard drug. All tested fractions were found active (except Per-1 at low dose of 100 mg/kg) with significant value (p < 0.001) compared to CCl₄ only group. Serum creatinine, malondialdehyde (MDA), and uric acid were significantly (p < 0.001) lowered in group VII-IX as compared to CCl₄ only group. Similarly, total protein (TP) and non-protein sulfhydryls(NP-SH) level in kidney tissues were significantly (p < 0.001) elevated in the same groups compared to CCl₄ only group. Further to check the cardio-protective potential, biochemical parameters such as LDH, creatine kinase, TP, MDA, and NP-SH levels in myocardial tissues were also estimated.These findings confirmed that the n-butanol and aqueous fractions are active and recommended for further bioactive phytoconstituents screening. Repeated column chromatography on silica gel G and sephadex-LH-20 of the active n-butanol fraction, four flavonoids were isolated. Based on the spectroscopic NMR data, compounds were identified as kaempferol (1), quercetin (2), astragalin (3), and rutin (4).

Migration and Proliferation Effects of Thymoquinone-Loaded Nanostructured Lipid Carrier (TQ-NLC) and Thymoquinone (TQ) on In Vitro Wound Healing Models

Wound healing is a regulated biological event that involves several processes including infiltrating leukocyte subtypes and resident cells. Impaired wound healing is one of the major problems in diabetic patients due to the abnormal physiological changes of tissues and cells in major processes. Thymoquinone, a bioactive compound found in Nigella sativa has been demonstrated to possess antidiabetic, anti-inflammatory, and antioxidant effects. Today, the rapidly progressing nanotechnology sets a new alternative carrier to enhance and favour the speed of healing process. In order to overcome its low bioavailability, TQ is loaded into a colloidal drug carrier known as a nanostructured lipid carrier (NLC). This study aimed to determine the effect of TQ-NLC and TQ on cell proliferation and migration, mode of cell death, and the antioxidant levels in normal and diabetic cell models, 3T3 and 3T3-L1. Cytotoxicity of TQ-NLC and TQ was determined by MTT assay. The IC10 values obtained for 3T3-L1 treated with TQ-NLC and TQ for 24 hours were 4.7 ± 3.3 and 5.3 ± 0.6 μM, respectively. As for 3T3, the IC10 values obtained for TQ-NLC and TQ at 24 hours were 4.3 ± 0.17 and 3.9 ± 2.05 μM, respectively. TQ-NLC was observed to increase the number of 3T3 and 3T3-L1 healthy cells (87-95%) and gradually decrease early apoptotic cells in time- and dose-dependant manner compared with TQ. In the proliferation and migration assay, 3T3-L1 treated with TQ-NLC showed higher proliferation and migration rate (p < 0.05) compared with TQ. TQ-NLC also acted as an antioxidant by reducing the ROS levels in both cells after injury at concentration as low as 3 μM. Thus, this study demonstrated that TQ-NLC has better proliferation and migration as well as antioxidant effect compared with TQ especially on 3T3-L1 which confirms its ability as a good antidiabetic and antioxidant agent.

Antioxidant properties of Korean major persimmon (Diospyros kaki) leaves

Persimmon is one of the most common native fruits of South Korea and its leaves are well known to be used in pharmaceuticals, cosmetics as well as beverages. The aim of this study was to compare the antioxidant properties of Korean major persimmon leaves on the basis of drying methods (hot air drying and freeze-drying) and harvesting time. Persimmon leaves from five cultivars ('Sangju-dungsi', 'Sangam-dungsi', 'Cheongdobansi', 'Gabjubaekmok' and 'Suhong') were harvested in late May and late June followed by blanching and drying. Results depicted that, persimmon leaves harvested in late May had the highest amount of antioxidants content compared to the late June. No significant difference was found between HAD and FD treatment with respect to total phenol, total flavonoid, tannin content, ABTS and DPPH radical-scavenging activity. Finally, it can be concluded that 'Gabjubaekmok' persimmon leaves collected during late May and dried by hot air are richer in antioxidants.

Effect of pre-treatment and extraction conditions on the antioxidant properties of persimmon (Diospyros kaki) leaves

Persimmon is a very delicious fruit and the leaves of this tree are used as a traditional drug. This study aimed to investigate the effects of drying method (hot air and freeze-drying), extraction temperature (80, 90 and 100 °C) and extraction time (10, 30, 60 and 120 min) and harvest stage (flowering and fruiting) on the antioxidant contents and antioxidant activity of persimmon leaves. The results showed that the highest antioxidants were obtained in both methods of drying. Also, 100 °C for 120 min of extraction gave the highest antioxidant contents, but with no significant difference compared to 90 °C for 60 min of extraction. Persimmon leaves collected during flowering stage had the maximum amount of antioxidants compared to the fruiting stage. Finally, it can be said that persimmon leaves harvested during flowering stage and treated by hot air drying with these extraction conditions (90 °C for 60 min) are richer in bioactive compounds.

Assessment of the Therapeutic Potential of Persimmon Leaf Extract on Prediabetic Subjects

Dietary supplements have exhibited myriads of positive health effects on human health conditions and with the advent of new technological advances, including in the fields of proteomics, genomics, and metabolomics, biological and pharmacological activities of dietary supplements are being evaluated for their ameliorative effects in human ailments. Recent interests in understanding and discovering the molecular targets of phytochemical-gene-protein-metabolite dynamics resulted in discovery of a few protein signature candidates that could potentially be used to assess the effects of dietary supplements on human health. Persimmon (Diospyros kaki) is a folk medicine, commonly used as dietary supplement in China, Japan, and South Korea, owing to its different beneficial health effects including anti-diabetic implications. However, neither mechanism of action nor molecular biomarkers have been discovered that could either validate or be used to evaluate effects of persimmon on human health. In present study, Mass Spectrometry (MS)-based proteomic studies were accomplished to discover proteomic molecular signatures that could be used to understand therapeutic potentials of persimmon leaf extract (PLE) in diabetes amelioration. Saliva, serum, and urine samples were analyzed and we propose that salivary proteins can be used for evaluating treatment effectiveness and in improving patient compliance. The present discovery proteomics study demonstrates that salivary proteomic profile changes were found as a result of PLE treatment in prediabetic subjects that could specifically be used as potential protein signature candidates.

Protective effects of marein on high glucose-induced glucose metabolic disorder in HepG2 cells

BACKGROUND

Our previous study has shown that Coreopsis tinctoria increases insulin sensitivity and regulates hepatic metabolism in high-fat diet (HFD)-induced insulin resistance rats. However, it is unclear whether or not marein, a major compound of C. tinctoria, could improve insulin resistance. Here we investigate the effect and mechanism of action of marein on improving insulin resistance in HepG2 cells.

METHODS

We investigated the protective effects of marein in high glucose-induced human liver carcinoma cell HepG2. In kinase inhibitor studies, genistein, LY294002, STO-609 and compound C were added to HepG2 cells 1h before the addition of marein. Transfection with siRNA was used to knock down LKB1, and 2-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG), an effective tracer, was used to detect glucose uptake.

RESULTS

The results showed for the first time that marein significantly stimulates the phosphorylation of AMP-activated protein kinase (AMPK) and the Akt substrate of 160kDa (AS160) and enhanced the translocation of glucose transporter 1 (GLUT1) to the plasma membrane. Further study indicated that genistein (an insulin receptor tyrosine kinase inhibitor) altered the effect of marein on glucose uptake, and both LY294002 (a phosphatidylinositol 3-kinase inhibitor) and compound C (an AMP-activated protein kinase inhibitor) significantly decreased marein-stimulated 2-NBDG uptake. Additionally, marein-stimulated glucose uptake was blocked in the presence of STO-609, a CaMKK inhibitor; however, marein-stimulated AMPK phosphorylation was not blocked by LKB1 siRNA in HepG2 cells. Marein also inhibited the phosphorylation of insulin receptor substrate (IRS-1) at Ser 612, but inhibited GSK-3β phosphorylation and increased glycogen synthesis. Moreover, marein significantly decreased the expression levels of FoxO1, G6Pase and PEPCK.

CONCLUSIONS

Consequently, marein improved insulin resistance induced by high glucose in HepG2 cells through CaMKK/AMPK/GLUT1 to promote glucose uptake, through IRS/Akt/GSK-3β to increase glycogen synthesis, and through Akt/FoxO1 to decrease gluconeogenesis. Marein could be a promising leading compound for the development of hypoglycemic agent or developed as an adjuvant drug for diabetes mellitus.

Persimmon (Diospyros kaki L.) leaves: a review on traditional uses, phytochemistry and pharmacological properties

ETHNOPHARMACOLOGICAL RELEVANCE

Persimmon (Diospyros kaki L.) leaves, known as Shi Ye (in Chinese), have a long history as a Chinese traditional medicine for the treatment of ischemia stroke, angina, internal hemorrhage, hypertension, atherosclerosis and some infectious diseases, etc. Additionally, persimmon leaves could be used as healthy products, cosmetics and so on, which have become increasingly popular in Asia, such as Japan, Korea and China etc.

AIM OF THE REVIEW

The present paper reviewed the ethnopharmacology, phytochemistry, analytical methods, biological activities and toxicology of persimmon leaves in order to assess the ethnopharmacological use and to explore therapeutic potentials and future opportunities for research.

MATERIALS AND METHODS

Information on persimmon leaves were gathered via the Internet (using Google Scholar, Baidu Scholar, Elsevier, ACS, Pudmed, Web of Science, CNKI and EMBASE) and libraries. Additionally, information was also obtained from some local books.

RESULTS

Persimmon leaves have played an important role in Chinese system of medicines. The main compositions of persimmon leaves were flavonoids, terpenoids, etc. Scientific studies on extracts and formulations revealed a wide range of pharmacological activities, such as, antioxidative, hypolipidemic, antidiabetic, antibacterial, hemostasis activities and effects on cardiovascular system. Based on the pharmacological activities, persimmon leaves were widely used in clinic including treatment of cardiovascular disease, hemostasis, antibacterial, anti-inflammatory and beauty treatment.

CONCLUSIONS

Persimmon leaves probably have therapeutic potential in the prevention and treatment for cerebral arteriosclerosis, diabetes, hypertension. It showed significant neuroprotection against ischemia/reperfusion injury in vivo and in vitro. Moreover, it can regulate immune function and inhibite inflammation. Further investigations are needed to explore individual bioactive compounds responsible for these pharmacological effects in vitro and in vivo and the mode of actions. Further safety assessments and clinical trials should be performed before it can be integrated into medicinal practices.

Rosiglitazone inhibits expression and secretion of PEDF in adipose tissue and liver of male SD rats via a PPAR-γ independent mechanism

Pigment epithelium-derived factor (PEDF) plays an important role in insulin resistance (IR). The study aims to investigate the effect of rosiglitazone, an insulin sensitizer, on PEDF production and release both in vivo and in vitro. Male SD rats were divided into normal control group, high-fat group, and rosiglitazone group. Hyperinsulinemic euglycemic clamp was performed to evaluate insulin sensitivity. IR models of 3T3-L1 adipocytes and HepG2 cells were established by the hyperinsulinemic method. Glucose uptake was examined to validate IR of adipocytes, and phosphorylation of protein kinase B and glycogen synthesis kinase 3β were examined to validate IR of HepG2 cells. Rosiglitazone, 2-chloro-5-nitro-N-phenylbenzamide (GW9662, an inhibitor of peroxisome proliferator-activated receptor-γ), and compound C (inhibitor of AMP-activated protein kinase [AMPK]) were used for the in vitro intervention. In vivo, the high-fat group showed increased serum PEDF levels, which negatively correlated with insulin sensitivity, whereas the rosiglitazone treatment decreased the serum PEDF and down-regulated PEDF expression in fat and liver of the obese rats, concomitant with significantly enhanced insulin sensitivity. In vitro, the IR cells showed increased PEDF secretion and expression, whereas rosiglitazone lowered PEDF secretion and expression, accompanied with increased insulin sensitivity. Interestingly, combination with 2-chloro-5-nitro-N-phenylbenzamide did not influence the effect of rosiglitazone on PEDF. However, rosiglitazone stimulated AMPK phosphorylation in fat and liver of the obese rats, whereas in vitro, when combined with compound C, the effect of rosiglitazone on PEDF was abrogated. In summary, rosiglitazone inhibits the expression and secretion of PEDF in fat and liver via promoting AMPK phosphorylation rather than peroxisome proliferator-activated receptor-γ, and changes of PEDF induced by rosiglitazone are closely associated with IR improvement.

Antihyperglycemic glucosylated coumaroyltyramine derivatives from Teucrium viscidum

Eight new glucosylated coumaroyltyramine derivatives, teuvissides A-H (1-8), were isolated from whole plants of Teucrium viscidum. Their structures were elucidated using spectroscopic data and chemical methods. The antihyperglycemic activities of these compounds were evaluated in HepG2 cells and 3T3-L1 adipocytes, and all of the isolates elicited different levels of glucose consumption at a concentration of 2.0 μM. Teuvissides A (1), B (2), and F (6) induced 2.2-, 2.1-, and 2.2-fold changes, respectively, in the levels of glucose consumption in HepG2 cells and 2.5-, 2.1-, and 2.3-fold changes, respectively, in 3T3-L1 adipocytes relative to the basal levels.

Metformin inhibits expression and secretion of PEDF in adipocyte and hepatocyte via promoting AMPK phosphorylation

OBJECTIVE

Pigment epithelium-derived factor (PEDF) plays an important role in obesity-induced insulin resistance (IR). The study aims to investigate the effect of metformin, a widely used agent to improve IR, on PEDF production both in vivo and in vitro.

METHODS

SD rats were divided into normal control group, high fat group (HF group), and metformin group (MET group). Hyperinsulinemic euglycemic clamp was performed to evaluate insulin sensitivity. IR models of 3T3-L1 and HepG2 cells were established and then treated with metformin and inhibitor of AMP activated protein kinase (AMPK).

RESULTS

In vivo, the HF group showed increased serum PEDF which is negatively correlated with insulin sensitivity, while the MET group revealed decreased serum PEDF and downregulated PEDF expression in fat and liver, concomitant with significantly improved IR. In vitro, the IR cells showed enhanced PEDF secretion and expression, whereas metformin lowered PEDF secretion and expression, accompanied with increased glucose uptake. Metformin stimulated AMPK phosphorylation in fat and liver of the obese rats, while in vitro, when combined with AMPK inhibitor, the effect of metformin on PEDF was abrogated.

CONCLUSIONS

Metformin inhibits the expression and secretion of PEDF in fat and liver via promoting AMPK phosphorylation, which is closely associated with IR improvement.

Supplementation of persimmon leaf ameliorates hyperglycemia, dyslipidemia and hepatic fat accumulation in type 2 diabetic mice

Persimmon Leaf (PL), commonly consumed as herbal tea and traditional medicines, contains a variety of compounds that exert antioxidant, α-amylase and α-glucosidase inhibitory activity. However, little is known about the in vivo effects and underlying mechanisms of PL on hyperglycemia, hyperlipidemia and hepatic steatosis in type 2 diabetes. Powered PL (5%, w/w) was supplemented with a normal diet to C57BL/KsJ-db/db mice for 5 weeks. PL decreased blood glucose, HOMA-IR, plasma triglyceride and total cholesterol levels, as well as liver weight, hepatic lipid droplets, triglycerides and cholesterol contents, while increasing plasma HDL-cholesterol and adiponectin levels. The anti-hyperglycemic effect was linked to decreased activity of gluconeogenic enzymes as well as increased glycogen content, glucokinase activity and its mRNA level in the liver. PL also led to a decrease in lipogenic transcriptional factor PPARγ as well as gene expression and activity of enzymes involved in lipogenesis, with a simultaneous increase in fecal lipids, which are seemingly attributable to the improved hyperlipidemia and hepatic steatosis and decreased hepatic fatty acid oxidation. Furthermore, PL ameliorated plasma and hepatic oxidative stress. Supplementation with PL may be an effective dietary strategy to improve type 2 diabetes accompanied by dyslipidemia and hepatic steatosis by partly modulating the activity or gene expression of enzymes related to antioxidant, glucose and lipid homeostasis.

Visualizing sweetness: increasingly diverse applications for fluorescent-tagged glucose bioprobes and their recent structural modifications

Glucose homeostasis is a fundamental aspect of life and its dysregulation is associated with important diseases, such as cancer and diabetes. Traditionally, glucose radioisotopes have been used to monitor glucose utilization in biological systems. Fluorescent-tagged glucose analogues were initially developed in the 1980s, but it is only in the past decade that their use as a glucose sensor has increased significantly. These analogues were developed for monitoring glucose uptake in blood cells, but their recent applications include tracking glucose uptake by tumor cells and imaging brain cell metabolism. This review outlines the development of fluorescent-tagged glucose analogues, describes their recent structural modifications and discusses their increasingly diverse biological applications.