Gracilaria chorda subcritical-water extracts as ameliorant of insulin resistance induced by high-glucose in zebrafish and dexamethasone in L6 myotubes.

Background and aim: Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to insulin. Loss of insulin sensitivity disrupts glucose homeostasis and elevates the risk of developing the metabolic syndrome that includes Type 2 diabetes. This study assesses the effect on subcritical-water extract of Gracilaria chorda (GC) at 210 °C (GCSW210) in IR induction models of high glucose (HG)-induced zebrafish larvae and dexamethasone (DEX)-induced L6 myotubes. Experimental procedure: The dose of HG and DEX for IR induction in zebrafish larvae and L6 myotubes was 130 mM or 0.5 µM. The capacity of glucose uptake was quantified by fluorescence staining or intensity. In addition, the activation of protein and mRNA expressions for insulin signaling (insulin-dependent or independent pathways) was measured. Results and conclusion: Exposure of zebrafish larvae to HG significantly reduced the intracellular glucose uptake with dose-dependnet manner compared to control. However, the group treated with GCSW210 significantly averted HG levels like the insulin-treated group, and significantly up- or down-regulated the mRNA expressions related to insulin production (insα) and insulin signaling pathways. Moreover, the treatment with GCSW210 effectively regulated the protein expression of PI3K/AKT, AMPK, and GLUT4 involved in the action of insulin in IR models of L6 myotubes compared to DEX-treated control. Our data indicate that GCSW210 stimulates activation of PI3K/AKT and AMPK pathways to attenuate the development of IR induced by HG in zebrafish and DEX in L6 myotubes. In conclusion, GCSW210 is a potential agent for alleviating various diseases associated with the insulin resistance.

Transcriptome analysis reveals differences in developmental neurotoxicity mechanism of methyl-, ethyl-, and propyl- parabens in zebrafish embryos.

Studies on the comparison of developmental (neuro) toxicity of parabens are currently limited, and unharmonized concentrations between phenotypic observations and transcriptome analysis hamper the understanding of their differential molecular mechanisms. Thus, developmental toxicity testing was conducted herein using the commonly used methyl- (MtP), ethyl- (EtP), and propyl-parabens (PrP) in zebrafish embryos. With a benchmark dose of 5%, embryonic-mortality-based point-of-departure (M-POD) values of the three parabens were determined, and changes in locomotor behavior were evaluated at concentrations of 0, M-POD/50, M-POD/10, and M-POD, where transcriptome analysis was conducted to explore the underlying neurotoxicity mechanism. Higher long-chained parabens were more toxic than short-chained parabens, as determined by the M-POD values of 154.1, 72.6, and 24.2 µM for MtP, EtP, and PrP, respectively. Meanwhile, exposure to EtP resulted in hyperactivity, whereas no behavioral effect was observed with MtP and PrP. Transcriptome analysis revealed that abnormal behaviors in the EtP-exposed group were associated with distinctly enriched pathways in signaling, transport, calcium ion binding, and metal binding. In contrast, exposure to MtP and PrP mainly disrupted membranes and transmembranes, which are closely linked to abnormal embryonic development rather than neurobehavioral changes. According to the changes in the expressions of signature mRNAs, tentative transcriptome-based POD values for each paraben were determined as MtP (2.68 µM), EtP (3.85 µM), and PrP (1.4 µM). This suggests that different molecular perturbations initiated at similar concentrations determined the extent and toxicity outcome differently. Our findings provide insight into better understanding the differential developmental neurotoxicity mechanisms of parabens.

Microbiota dysbiosis associated with type 2 diabetes-like effects caused by chronic exposure to a mixture of chlorinated persistent organic pollutants in zebrafish.

Mixtures of chlorinated persistent organic pollutants (C-POPs-Mix) are chemically related risk factors for type 2 diabetes mellitus (T2DM); however, the effects of chronic exposure to C-POPs-Mix on microbial dysbiosis remain poorly understood. Herein, male and female zebrafish were exposed to C-POPs-Mix at a 1:1 ratio of five organochlorine pesticides and Aroclor 1254 at concentrations of 0.02, 0.1, and 0.5 µg/L for 12 weeks. We measured T2DM indicators in blood and profiled microbial abundance and richness in the gut as well as transcriptomic and metabolomic alterations in the liver. Exposure to C-POPs-Mix significantly increased blood glucose levels while decreasing the abundance and alpha diversity of microbial communities only in females at concentrations of 0.02 and 0.1 µg/L. The majorly identified microbial contributors to microbial dysbiosis were Bosea minatitlanensis, Rhizobium tibeticum, Bifidobacterium catenulatum, Bifidobacterium adolescentis, and Collinsella aerofaciens. PICRUSt results suggested that altered pathways were associated with glucose and lipid production and inflammation, which are linked to changes in the transcriptome and metabolome of the zebrafish liver. Metagenomics outcomes revealed close relationships between intestinal and liver disruptions to T2DM-related molecular pathways. Thus, microbial dysbiosis in T2DM-triggered zebrafish occurred as a result of chronic exposure to C-POPs-Mix, indicating strong host-microbiome interactions.

Synergetic effects of concurrent chronic exposure to a mixture of OCPs and high-fat diets on type 2 diabetes and beneficial effects of caloric restriction in female zebrafish.

This study aimed to investigate the relationship among chronic exposure to a low concentration of organochlorine pesticides (OCPs), high-fat diet (HFD)-induced obesity, and caloric restriction in type 2 diabetes (T2D). Thus, female zebrafish were divided into four groups and treated for 12 weeks as follows: (i) negative control, (ii) HFD (obesity) control, (iii) obesity + a mixture of OCPs (OP), and (iv) obesity + a mixture of OCPs + caloric restriction (OPR). We then assessed T2D-related effects via hematological analysis, histopathology, mitochondrial evaluation, and multiomics analyses. The OP group showed a significant increase in glucose levels, whereas the OPR group maintained glucose at nonsignificant levels. Multiomics analyses revealed that the exacerbated metabolic effects in the OP group were associated with molecular alterations in oxidative stress, inflammation, nucleotide metabolism, and glucose/lipid homeostasis. These alterations were histologically verified by the increased numbers of hypertrophic adipocytes and inflammatory cells observed. Caloric restriction activated pathways related to antioxidant response, mitochondrial fatty acid oxidation, and energy metabolism in zebrafish, leading to preserved glucose homeostasis. In conclusion, this study identified molecular mechanisms underlying the synergistic effect of concurrent exposure to a mixture of OCPs and HFD as well as shed light on the beneficial effect of regular caloric restriction in T2D development.

Exposure to a low concentration of mixed organochlorine pesticides impairs glucose metabolism and mitochondrial function in L6 myotubes and zebrafish.

More realistic effects on glucose metabolic dysfunction can be evaluated by applying organochlorine (OCP) mixtures than individual OCPs. We formulated an equal ratio mixture of five OCPs (chlordane, heptachlor, p,p'-dichlorodiphenyltrichloroethane, ß-hexachlorocyclohexane, and hexachlorobenzene) and treated L6 myotubes with this OCP mixture to investigate effects on glucose uptake and the underlying mechanism. Exposure to the OCP mixture reduced 2-NBDG staining, representing glucose uptake, and stimulated the excessive production of reactive oxygen species (ROS). Reduced 2-NBDG uptake and ROS overproduction were compensated by insulin treatment. The expression of proteins such as IRß, PI3K, and AKT was downregulated, indicating that ROS overproduction contributed to the inhibition of insulin-dependent glucose uptake. Reduction in mitochondria quantity and decreased expression levels of PGC-1α, PDH, and GLUT4 proteins were observed, suggesting that mitochondrial dysfunction played a causative role in the disruption of glucose uptake. The inhibition of glucose uptake and ROS overproduction caused by the OCP mixture were also found in zebrafish as an in vivo model. We demonstrated that exposure to the OCP mixture, even at the lowest concentration, perturbed glucose uptake, which was associated with mitochondrial dysfunction, suggesting that an OCP mixture could be a potential environmental factor in type 2 diabetes-related effects on skeletal muscles.

Caulerpa okamurae extract attenuates inflammatory interaction, regulates glucose metabolism and increases insulin sensitivity in 3T3-L1 adipocytes and RAW 264.7 macrophages.

OBJECTIVE: To examine whether Caulerpa okamurae ethanolic extract (COE) could inhibit obesity-mediated inflammation, improve glucose metabolism and increase insulin sensitivity, using in vitro cell models of RAW 264.7 macrophages and 3T3-L1 adipocytes. METHODS: We cocultured 3T3-L1 adipocytes in direct contact with lipopolysaccharide-stimulated RAW 264.7 macrophages and induced insulin resistance in 3T3-L1 adipocytes with tumor necrosis factor-α (TNF-α) in the presence or absence of 250 µg/mL of COE. We investigated various markers of inflammation, glucose regulation and insulin sensitivity in these models using Griess reagent to measure nitric oxide (NO) production, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxyglucose to measure glucose uptake, Western blot analysis to quantify protein expression and reverse transcriptase-polymerase chain reaction to evaluate mRNA expression. RESULTS: We found that COE (250 µg/mL) significantly inhibited the lipopolysaccharide-induced inflammatory response in RAW 264.7 macrophages by downregulating NO production, nitric oxide synthase 2 expression and nuclear translocation of nuclear factor-κB. COE also showed similar anti-inflammatory activity in coculture, along with decreased TNF-α, interleukin-6 and monocyte chemoattractant protein mRNA expression. In addition, COE also improved glucose uptake in coculture by upregulating glucose transporter-4 (GLUT-4) and adiponectin and reducing serine phosphorylation of insulin receptor substrate-1 (IRS1). In the TNF-α-induced insulin resistance model of 3T3-L1 adipocytes, COE significantly improved both basal and insulin-stimulated glucose uptake, accompanied by phosphorylation of IRS1 at tyrosine 632, phospho-5' adenosine monophosphate-activated protein kinase α and glycogen synthase kinase-3ß (Ser9) as well as upregulation of GLUT-4. CONCLUSION: Together, these findings suggest that COE has potential to treat or prevent obesity-induced metabolic disorders.

Low-concentration exposure to organochlorine pesticides (OCPs) in L6 myotubes and RIN-m5F pancreatic beta cells induces disorders of glucose metabolism.

We selected five substances among the organochlorine pesticides (OCPs), chlordane, heptachlor, p,p'-DDT, ß-HCH, and hexachlorobenzene, and investigated whether low-concentration exposure to the OCP compounds affected glucose metabolism. The exposure of L6 myotubes to the OCP compounds (1 or 5 µM) for 24 and 48 h significantly inhibited glucose uptake with an excessive production of intracellular reactive oxygen species (ROS) and peroxynitrite anions (ONOO-) compared to control cells. In contrast, the production of nitric oxide was highly reduced by exposure to the OCP compounds. The protein expression of glucose transporter 4 (GLUT4) in the L6 myotubes was significantly suppressed by exposure to the OCP compounds. In addition, exposure to the OCP compounds for 1 h in RIN-m5F pancreatic beta cells remarkably suppressed insulin secretion but the ability to secrete insulin recovered to control levels after 24 h exposure to the OCP compounds. The abundant ROS generated by 1 h exposure to OCP compounds was inversely related to insulin secretion in RIN-m5F pancreatic beta cells. Therefore, these results suggest that low-concenration exposure of skeletal muscle and pancreatic beta cells to OCP compounds may affect insulin secretion and insulin-dependent glucose uptake through extreme oxidative stress and inactivation of the glucose transport protein.

Tinospora cordifolia preserves pancreatic beta cells and enhances glucose uptake in adipocytes to regulate glucose metabolism in diabetic rats.

The purpose of this study was to evaluate the pancreatic beta cell protective and glucose uptake enhancing effect of the water extract of Tinospora cordifolia stem (TCSE) by using rat insulinoma (RIN)-m5F cells and 3 T3-L1 adipocytes. RIN-m5F cells were stimulated with interleukin-1ß and interferon-γ, and the effect of TCSE on insulin secretion and cytokine-induced toxicity was measured by ELISA and MTT assay, respectively. The glucose uptake and protein expression were measured by fluorometry and western blotting. Antidiabetic effect of TCSE was measured using streptozotocin-induced diabetic rats. TCSE dose dependently increased cell viability and insulin secretion in RIN-m5F cells. In addition, TCSE increased both the glucose uptake and glucose transporter 4 translocation in 3 T3-L1 adipocytes via PI3K pathway. Finally, TCSE significantly lowered blood glucose and diet intake and increased body weight in streptozotocin-induced diabetic rats. The level of serum insulin and hepatic glycogen was increased, whereas the level of serum triglyceride, total cholesterol, dipeptidyl peptidase-4, and thiobarbituric acid reactive substances was decreased in TCSE-administered rats. TCSE also increased glucose transporter 4 protein expression in the adipose tissue and liver of TCSE-fed diabetic rats. Our results suggested that TCSE preserved RIN-m5F cells from cytokine-induced toxicity and enhanced glucose uptake in 3 T3-L1 adipocytes, which may regulate glucose metabolism in diabetic rats.

Caulerpa okamurae extract inhibits adipogenesis in 3T3-L1 adipocytes and prevents high-fat diet-induced obesity in C57BL/6 mice.

Seaweeds are considered a potential source of antiobesity agents. Because Caulerpa, a seaweed, has been consumed for food in Japan, China, South Korea, and Australia, we hypothesized that Caulerpa okamurae may have antiobesity effects in an animal model of high-fat diet (HFD)-induced obesity in C57BL/6 mice. Herein, we found that the ethanolic extract of C okamurae (COE) significantly inhibited lipid accumulation and reduced the expression of the master regulator of adipogenesis, peroxisome proliferator-activated receptor-γ, sterol regulatory element binding protein-1c, and CCAAT/enhancer-binding protein-α in 3T3-L1 adipocytes. Moreover, COE significantly decreased body weight, fat weight, and liver weight in HFD-fed mice. This effect is comparable to that of positive control Garcinia cambogia extract, which has been approved by the Korean Food and Drug Administration as a weight loss food supplement in South Korea. Similarly, markers of weight gain such as free fatty acids, triglyceride, total cholesterol, glucose, and insulin in the plasma and free fatty acid, triglyceride, total cholesterol, and total lipid in the liver are significantly reduced in COE-treated HFD-fed mice. We found significantly reduced peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein-α, fatty acid synthase, sterol regulatory element binding protein-1c, cluster of differentiation 36, and acetyl-CoA synthetase in the adipose tissue of COE-treated HFD-fed mice. In conclusion, our results demonstrated that COE is effective in preventing body weight gain and fat accumulation and reduces plasma and hepatic lipid profiles. Together, these findings suggest that C okamurae may be used as a possible treatment option for the management of obesity and associated metabolic disorders.

Anti-nociceptive and anti-inflammatory effects of the methanolic extract of Opuntia humifusa stem.

OBJECTIVE: Opuntia humifusa (O. humifusa) Raf. has been used for the prevention and treatment of rheumatoid arthritis, inflammation, and cancer. Our study was designed to unveil the anti-nociceptive and anti-inflammatory effects of the methanolic extract of O. humifusa Raf stem (OHS). MATERIALS AND METHODS: The anti-nociceptive effect was measured by hot plate, acetic acid-induced writhing, and tail flick assays in mice and rats. Moreover, the anti-inflammatory effect was measured by vascular permeability and carrageenan and serotonin-induced paw edema tests in rats. Furthermore, anti-inflammatory effect was also measured using macrophage-like LPS-induced RAW 264.7 cells. RESULTS: OHS extract inhibited acetic acid-induced writhing (p<0.0001), and delayed the reaction time of mice to the hot plate-induced thermal stimulation (p<0.0001) and tail flick tests (p<0.05). OHS extract attenuated the carrageenan and serotonin-induced paw edema in rats (p<0.001). Similarly, OHS extract significantly decreased Evans blue concentration in acetic acid induced vascular permeability test (p<0.0001), revealing its strong anti-inflammatory effect. Finally, among four different fractions of OHS extract, n-butanol fraction strongly decreased NO production (p<0.0001) and iNOS expression in LPS-induced RAW 264.7 cells. CONCLUSION: Our results suggest that the methanolic extract of O. humifusa stem can be used to develop a therapeutic or supportive drug and/or functional food against pain and inflammation related diseases.

Anti-inflammatory effects and mechanisms of Hizikia fusiformis via multicellular signaling pathways in lipopolysaccharide-induced RAW 264.7 cells.

In this study, we investigated the anti-inflammatory effects and mechanisms of Hizikia fusiformis (HF) extracts in lipopolysaccharide (LPS)-induced RAW 264.7 cells. We extracted HF using solvent and sub-critical water techniques. In results, HF extracts inhibited nitric oxide (NO) production in cell-free and LPS-stimulated RAW 264.7 cells. HF210 (extract prepared with sub critical water at 210oC) was most effective. The HF210 extract dose-dependently inhibited inducible nitric oxide synthase expression (iNOS) and nuclear factor kappa (NF-B) p65 translocation from cytosol to the nucleus. Furthermore, HF210 extract dose-dependently inhibited the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), Jun N-terminal kinase (JNK), and signal transducers and activators of transcription (STAT)-1in LPS-induced RAW 264.7 cells. Thus, our results suggest that anti-inflammatory effects of HF210 extract showed a noticeable distinction by regulation of multiple signaling pathways in LPS-induced RAW 264.7 cells.

Korean Chungtaejeon tea extract attenuates body weight gain in C57BL/6J-Lep ob/ob mice and regulates adipogenesis and lipolysis in 3T3-L1 adipocytes.

OBJECTIVE: Traditional Korean Chungtaejeon (CTJ) tea is a type of fermented tea, which has received increasing attention in recent years because of its purported health benefits. The present study was designed to investigate the effect and mechanism of CTJ tea extract on body weight gain using C57BL/6J-Lep ob/ob mice and 3T3-L1 adipocytes, respectively. METHODS: The effects of CTJ on cell viability, lipid accumulation, and expression of protein and mRNA were measured in 3T3-L1 adipocytes by using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, oil red O staining, Western blotting, and reverse transcriptase-polymerase chain reaction analyses. C57BL6J-Lep ob/ob mice were administered with CTJ (200 or 400 mg/kg body weight) for ten weeks. Then, body weight, food intake, total cholesterol, and triglyceride were measured in ob/ob mice. RESULTS: CTJ tea extract treated at 250 µg/mL (CTJ250) significantly suppressed lipid accumulation in the differentiated 3T3-L1 adipocytes. Likewise, CTJ250 significantly decreased the protein expression of peroxisome proliferator-activated receptorγ (PPARγ), CCAAT/enhancer-binding protein α, and adipocyte lipid-binding protein, and regulated the mRNA expression of PPARγ, sterol regulatory element-binding protein-1c gene, fatty acid synthase, adipocyte lipid-binding protein, hormone-sensitive lipase, carnitine palmitoyl transferase 1, cluster of differentiation 36, and acetyl-CoA carboxylase in the differentiated 3T3-L1 adipocytes. Mice administered with CTJ showed dose-dependent decrease in body weight gain, starting from week 4 of the experiment. CTJ tea extract administered at 400 mg/kg body weight significantly decreased fat mass, food efficacy ratio, and levels of plasma triglyceride and total cholesterol. CONCLUSION: CTJ attenuated weight gain in ob/ob mice and regulated the activity of the molecules involved in adipogenesis and lipolysis in 3T3-L1 adipocytes. CTJ is a potentially valuable herbal therapy for the prevention of obesity and/or obesity-related disorders.

Caulerpa lentillifera inhibits protein-tyrosine phosphatase 1B and protects pancreatic beta cell via its insulin mimetic effect.

The aim of this study was to determine whether Caulerpa lentillifea extract (CLE) can protect pancreatic beta cells and enhance insulin signaling in adipocytes. We measured the protein tyrosine phosphatase (PTP)-1B inhibitory effect of CLE using an in-vitro enzyme assay. Proteins involved in the pancreatic beta-cell death and insulin signaling were measured by western blotting. Oil-red O staining was used to measure the insulin mimetic effect of CLE. CLE strongly inhibited the PTP1B enzyme. In rat insulinoma (RIN)-m5F cells, CLE decreased the activation of extracellular regulated kinase (ERK)-1/2, P38 mitogen activated protein kinase (P38), c-Jun NH2-terminal kinase (JNK), and nuclear factor kappa-light-chain-enhancer of the activated B cells (NF-κB). Furthermore, CLE showed insulin-mimetic effect and enhanced the activation of insulin-signaling molecules including IRS, AKT, PI3K, and GSK-3ß in 3T3-L1 adipocytes. Our results suggested that CLE-inhibited PTP1B, protected the pancreatic beta cells, and enhanced insulin sensitization in the adipocytes.

Nelumbo Nucifera leaf extract attenuated pancreatic ß-cells toxicity induced by interleukin-1ß and interferon-γ, and increased insulin secrection of pancreatic ß-cells in streptozotocin-induced diabetic rats.

OBJECTIVE: To evaluate the effect of Nelumbo Nucifera leaf water extract (NNLE) on insulinoma (RIN) cells induced by interleukin-1ß (IL-1ß) and interferon-g (IFN-γ), and injured pancreatic ß-cells induced by Streptozotocin (STZ) in rats. METHODS: The anti-oxidative effects of NNLE were assessed using 1,1-diphenyl-2-picryl hydrazyl (DPPH) and nitric oxide (NO) scavenging assays. The inhibitory effect of NNLE on α-glucosidase and DPP (dipeptidyl peptidase)-IV was measured in vitro. Pancreatic ß-cell protective and insulin secretory effects were assessed, using IL-1ß and IFN-γ-induced rat RIN cells. STZ-induced diabetic rats were treated with 50, 100, and 400 mg/kg NNLE for 4 weeks. The effects of NNLE on blood glucose (BG), body weight (BW), and lipid profiles were measured. RESULTS: NNLE inhibited DPPH, NO, α-glucosidase, and DPP-IV which were directly linked to the function of ß-cells. Furthermore, NNLE protected RIN cells from toxicity induced by IL-1ß and IFN-γ, decreased NO production, and increased insulin secretion. NNLE caused a significant reduction in blood glucose, triglyceride (TG), total cholesterol (TC), blood urea nitrogen (BUN), and creatinine in STZ-induced diabetic rats. Furthermore, it significantly decreased BW loss in STZ-induced diabetic rats. CONCLUSION: Our results suggest that NNLE reduced the toxicity in insulinoma cells and increased insulin secretion in pancreatic ß-cells in STZ-induced diabetic rats.

Anti-Obesity Effects of the Mixture of Eriobotrya japonica and Nelumbo nucifera in Adipocytes and High-Fat Diet-Induced Obese Mice.

The present study is to evaluate the anti-obesity effects of Eriobotrya japonica (EJ), Nelumbo nucifera (NN), and their mixture (MIX, 1:1 ratio) in 3T3-L1 adipocytes and high-fat diet-induced obese mice. The treatment of EJ, NN, and MIX in 3T3-L1 adipocytes effectively inhibited lipid accumulation, significantly decreased expression of peroxisome proliferator-activated receptor gamma (PPARγ), sterol regulatory element binding protein (SREBP1c), and adipocyte lipid-binding protein (aP2), and significantly increased phosphorylation of AMP-activated protein kinase (AMPK). Moreover, oral treatment of MIX showed stronger effects than individual treatment. C57BL/6J mice (6 week old) were divided into two groups; low fat diet (LFD) containing 10% calories from fat and high fat diet (HFD) containing 60% calories from fat. The HFD groups were further divided into five subgroups; treated with distilled water (HFD), treated with 400 mg/kg EJ (EJ400), treated with 400 mg/kg NN (NN400), treated with 200 mg/kg MIX (MIX200), and treated with 400 mg/kg MIX (MIX400) during 13 weeks. In our results, the administration of EJ, NN, and MIX significantly decreased body weight (BW), fat weight, liver weight, hepatic triglyceride (TG) and total cholesterol (TC), lipid droplets in the liver, food efficacy ratio, and the plasma TG, TC, glucose, insulin, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in a dose-dependent manner, and MIX treatment showed stronger effect than their individual treatments. Similarly, MIX treatment decreased the expression of PPARγ, SREBP-1c, FAS, and ACC more strongly in the adipose tissue than single treatments. In conclusion, the MIX of EJ and NN extract may strongly regulate BW gain than EJ or NN alone, and its anti-obesity effect is associated with the control of lipid metabolism, including adipogenesis and lipogenesis.

Selaginellin and biflavonoids as protein tyrosine phosphatase 1B inhibitors from Selaginella tamariscina and their glucose uptake stimulatory effects.

As part of an ongoing search for new antidiabetic agents from medicinal plants, the methanol extract of the aerial parts of Selaginella tamariscina was found to possess stimulatory effect on glucose uptake in 3T3-L1 adipocyte cells. Thus, bioassay-guided isolation of this active extract yielded two new compounds (1 and 2) along with five known biflavonoids (3-7). Their structures were elucidated by extensive analysis of spectroscopic and physicochemical data. The absolute configuration of compound 2 was determined by specific rotation and CD data analysis. All isolates exhibited potent inhibitory effects on PTP1B enzyme with IC50 values ranging from 4.5±0.1 to 13.2±0.8µM. Furthermore, the isolates (1-7) showed significant stimulatory effects on 2-NBDG uptake in 3T3-L1 adipocyte cells. Of these, compounds (1, 6, and 7) which exhibited mixed-competitive inhibition modes against PTP1B, showed potent stimulatory effects on 2-NBDG uptake. This result indicated the potential of these biflavonoids as lead molecules for development of antidiabetic agents and the beneficial use of S. tamariscina against hyperglycemia.

Caulerpa lentillifera extract ameliorates insulin resistance and regulates glucose metabolism in C57BL/KsJ-db/db mice via PI3K/AKT signaling pathway in myocytes.

BACKGROUND: Glucose homeostasis is distorted by defects of the PI3K/AKT and AMPK pathways in insulin-sensitive tissues, allowing the accumulation of glucose in the blood. The purpose of this study was to assess the effects and mechanisms by which ethanol extract of Caulerpa lentillifera (CLE) regulates glucose metabolism in C57BL/KsJ-db/db (db/db) mice. METHODS: Mice were administered CLE (250 or 500 mg/kg BW) or rosiglitazone (RSG, 10 mg/kg BW) for 6 weeks. Then, oral glucose tolerance test (OGTT) and intraperitoneal insulin tolerance test (IPITT) were performed, and blood glucose was measured in db/db mice. Levels of insulin and insulin resistance factors in plasma, glycogen content in the liver, and IRS, PI3K, AKT, and GLUT4 expressions in skeletal muscles were measured in db/db mice. Glucose uptake and insulin signaling molecules were measured in L6 myocytes, using fluorometry and Western blotting. RESULTS: CLE significantly decreased fasting blood glucose, glucose level in OGTT and IPITT, plasma insulin, homeostatic model assessment-insulin resistant (HOMA-IR), TNF-α, IL-6, FFA, TG and TC levels, and hepatic glycogen content in db/db mice. CLE significantly increased the activation of IRS, AKT, PI3K, and GLUT4, which are the key effector molecules of the PI3K/AKT pathway in L6 myocytes and the skeletal muscles of db/db mice. The enhanced glucose uptake by CLE was abolished by treatment with a PI3K inhibitor (LY294002), but not by an AMPK inhibitor (compound C) in L6 myocytes. CLE regulated glucose uptake and homeostasis via the PI3K/AKT pathway in myocytes and db/db mice, respectively. CONCLUSION: Our results suggest that CLE could be a potential candidate for the prevention of diabetes.

Lespedeza davurica (Lax.) Schindl. extract protects against cytokine-induced ß-cell damage and streptozotocin-induced diabetes.

Lespedeza has been used for the management of diabetes in folklore medicine. The purpose of this study is to investigate the protective effects of the methanol extract of Lespedeza davurica (LD) on cytokine-induced ß-cell damage and streptozotocin- (STZ-) induced diabetes. RINm5F cells were treated with interleukin- (IL-) 1ß and interferon- (IFN-) γ to induce pancreatic ß-cell damage. The exposure of LD extract significantly decreased cell death, nitric oxide (NO) production, nitric oxide synthase (iNOS) expression, and nucleus factor-kappa B (NF-κB) p65 activation. Antidiabetic effects of LD extract were observed by oral glucose tolerance test (OGTT) in normal rats and by checking the biochemical, physiological, and histopathological parameters in STZ-induced diabetic rats. In OGTT, glucose clearance levels improved by oral treatment of LD extract. The water intake, urine volume, blood glucose, and serum TG, TC, TBARS, and DPP-IV levels were significantly decreased, and liver glycogen content was significantly increased by treatment of LD extract (250 mg/kg BW) in STZ-induced diabetic rats. Also, insulin immunoreactivity of the pancreases was increased in LD extract administrated rats compared with diabetic control rats. These results indicate that LD extract may protect pancreatic ß-cell damage and regulate the blood glucose in STZ-induced diabetic rats.

Insulin-mimetic selaginellins from Selaginella tamariscina with protein tyrosine phosphatase 1B (PTP1B) inhibitory activity.

As part of an ongoing search for new antidiabetic agents from medicinal plants, three new (2, 4, and 5) and two known selaginellin derivatives (1 and 3) were isolated from a methanol extract of Selaginella tamariscina. The structures of the new compounds were determined by spectroscopic data analysis. All isolates showed strong glucose uptake stimulatory effects in 3T3-L1 adipocyte cells at a concentration of 5 µM. Furthermore, these compounds were found to possess inhibitory effects on PTP1B enzyme activity with IC50 values ranging from 4.6 ± 0.1 to 21.6 ± 1.5 µM. Compound 2 showed the greatest potency, with an IC50 value of 4.6 ± 0.1 µM, when compared with the positive control (ursolic acid, IC50 = 3.5 ± 0.1 µM). Therefore, these selaginellin derivatives may have value as new lead compounds for the development of agents against type 2 diabetes.

Anti-diabetic effects of Caulerpa lentillifera: stimulation of insulin secretion in pancreatic ß-cells and enhancement of glucose uptake in adipocytes.

OBJECTIVE: To evaluate anti-diabetic effect of Caulerpa lentillifera (C. lentillifera). METHODS: The inhibitory effect of C. lentillifera extract on dipeptidyl peptidase-IV and α-glucosidase enzyme was measured in a cell free system. Then, interleukin-1ß and interferon-γ induced cell death and insulin secretion were measured in rat insulinoma (RIN) cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and ELISA kit, respectively. Glucose uptake and glucose transporter expression were measured by fluorometry and western blotting, using 3T3-L1 adipocytes. RESULTS: C. lentillifera extract significantly decreased dipeptidyl peptidase-IV and α-glucosidase enzyme activities, and effectively inhibited cell death and iNOS expression in interleukin-1ß and interferon-γ induced RIN cells. Furthermore, C. lentillifera extract significantly enhanced insulin secretion in RIN cells and glucose transporter expression and glucose uptake in 3T3-L1 adipocytes. CONCLUSIONS: Thus, our results suggest that C. lentillifera could be used as a potential anti-diabetic agent.