Antihyperglycemic effect of a caffeamide derivative, KS370G, in normal and diabetic mice

N-Octyl Caffeamide, a Caffeic Acid Amide Derivative, Prevents Progression of Diabetes and Hepatic Steatosis in High-Fat Diet Induced Obese Mice

The underlying pathological mechanisms of diabetes are complicated and varied in diabetic patients, which may lead to the current medications often failing to maintain glycemic control in the long term. Thus, the discovery of diverse new compounds for developing medicines to treat diabetes and its complications are urgently needed. Polyphenols are metabolites of plants and have been employed in the prevention and treatment of a variety of diseases. Caffeic acid phenethyl ester (CAPE) is a category of compounds structurally similar to polyphenols. In this study, we aimed to investigate the antidiabetic activity and potential molecular mechanisms of a novel synthetic CAPE derivative N-octyl caffeamide (36M) using high-fat (HF) diet induced obese mouse models. Our results demonstrate that 36M prevented the progression of diabetes in the HF diet fed obese mice via increasing phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and inhibiting expression of protein tyrosine phosphatase 1B (PTP1B). We also found that 36M could prevent hepatic lipid storage in the HF diet fed mice via inhibition of fatty acid synthase and lipid droplet proteins, including perilipins and Fsp27. In conclusion, 36M is a potential candidate compound that can be developed as AMPK inhibitor and PTP1B inhibitor for treating diabetes and hepatic steatosis.

In Vitro Antimicrobial Potential of CAPE and Caffeamide Derivatives against Oral Microbes

Caffeic acid phenethyl ester (CAPE) is a natural component isolated from propolis and used in traditional medicine. We aimed to investigate the antimicrobial properties and action mechanism of CAPE and caffeamide derivatives (26G and 36M) against oral disease microbes. We resolved the minimum inhibitory and bactericidal concentrations of 26G and 36M and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation and antibiotic resistance gene expression in methicillin-resistant Staphylococcus aureus (MRSA). Our results revealed that 26G and 36M showed the best anticancer and antimicrobial activities, respectively, compared with the other four caffeamide derivatives. Both 26G and 36M showed heat-dependent decreases in antimicrobial activity. The 36M derivative was stable irrespective of pH, whereas 26G was not stable under high pH conditions. Biofilm formation and antibiotic resistance-related gene expression were consistent with their respective phenotypes. This study provides evidence for the potential application of CAPE and caffeamide derivatives in dental medicine to cure or prevent oral diseases.

Adlay hull extracts attenuate β-amyloid-induced neurotoxicity and oxidative stress in PC12 cells through antioxidative, anti-inflammatory, and antiapoptotic activities

Alzheimer's disease (AD) is characterized by accumulation of β-amyloid (Aβ) in senile plaques, contributing to oxidative stress, mitochondrial diseases, and synaptic atrophy, consequently leading to the deterioration of brain function. Adlay (Coix lacryma-jobi L.) is an annual botanical. Here, a 95% ethanol extract of adlay hull (AHEE) was partitioned by ethyl acetate (AHEAE), n-butanol (AHBUE), and water (AHWE), and the effects of these extracts on lipopolysaccharide (LPS)-induced RAW264.7 cells and Aβ-induced PC12 cells, as experimental models of neurotoxicity, were evaluated. The expression of anti-inflammatory and antiapoptosis-related proteins was investigated and AHEE, AHEAE, and AHWE were found to exert anti-inflammatory effects. AHWE exhibited antiapoptotic effects and inhibited inducible nitric oxide synthase expression and nitric oxide production. We investigated the protective effects of AHWE against Aβ-induced neurotoxicity in dPC12 cells and explored the underlying mechanism. Pretreatment with AHWE significantly attenuated cell death and Aβ-mediated increase in B cell lymphoma (Bcl)-2/Bax ratio. AHWE significantly inhibited Aβ and enhanced protein kinase B (Akt) level in dPC12 cells, suggesting that its protective effect against Aβ-induced apoptosis in dPC12 cells was mediated through upregulation of the phosphoinositide 3-kinases (PI3K)/Akt signaling pathway. These extracts and its bioactive compound K36-21 may be potentially useful to treat neurodegenerative disorders.

Design, Synthesis of N-phenethyl Cinnamide Derivatives and Their Biological Activities for the Treatment of Alzheimer's Disease: Antioxidant, Beta-amyloid Disaggregating and Rescue Effects on Memory Loss

Gx-50 is a bioactive compound for the treatment of Alzheimer’s disease (AD) found in Sichuan pepper (Zanthoxylum bungeanum). In order to find a stronger anti-AD lead compound, 20 gx-50 (1–20) analogs have been designed and synthesized, and their molecular structures were determined based on nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis, as well as comparison with literature data. Compounds 1–20 were evaluated for their anti-AD potential by using DPPH radical scavenging assay for considering their anti-oxidant activity, thioflavin T (ThT) fluorescence assay for considering the inhibitory or disaggregate potency of Aβ, and transgenic Drosophila model assay for evaluating their rescue effect on memory loss. Finally, compound 13 was determined as a promising anti-AD candidate.

Bright Side of Lignin Depolymerization: Toward New Platform Chemicals

Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products. Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many creative strategies emerged that deliver defined products via catalytic or biocatalytic depolymerization in good yields. The purpose of this review is to provide insight into these novel approaches and the potential application of such emerging new structures for the synthesis of biobased polymers or pharmacologically active molecules. Existing strategies for functionalization or defunctionalization of lignin-based compounds are also summarized. Following the whole value chain from raw lignocellulose through depolymerization to application whenever possible, specific lignin-based compounds emerge that could be in the future considered as potential lignin-derived platform chemicals.

Inhibitory effects of hydroxylated cinnamoyl esters on lipid absorption and accumulation

Obesity is a risk factor associated with several lifestyle-related diseases, for example, diabetes, high blood pressure, hyperlipidemia and cancer. Caffeic acid 2-phenylethyl ester (CAPE, 1), a naturally-occurring compound found in various plants and propolis, which exhibits anti-inflammatory, immunomodulatory and cytotoxic activities and inhibits 3T3-L1 differentiation to adipocytes. As part of our efforts to moderate lifestyle-related diseases, we synthesized analogs of 1 and studied their effects on pancreatic lipase activities, lipid absorption, and 3T3-L1 differentiation. We found that catechols 1-4 show inhibitory activities against pancreatic lipase in a dose-dependent manner in vitro. Compounds 1-3 proved to be more potent inhibitors of pancreatic lipase than 5, 6, 8, and 9, which have one hydroxyl group, respectively. Compound 7 has three aromatic hydroxyl groups and restrains greater lipase inhibitory activity than the other compounds. In addition, 7 and 3 significantly suppress a rise in blood triglyceride (TG) levels in mice given corn oil orally. Furthermore, 2 and 3 are more potent at preventing 3T3-L1 differentiation (lipid accumulation) than 1, while 7 is more potent than 3, 8, and 9 in these assays. Compounds 2, 3, and 7 inhibit lipid absorption and accumulation, with new compound 7 being the most potent. These results indicate that 7 may have potential benefits as a health agent with anti-obesity properties.

Caffeamide 36-13 Regulates the Antidiabetic and Hypolipidemic Signs of High-Fat-Fed Mice on Glucose Transporter 4, AMPK Phosphorylation, and Regulated Hepatic Glucose Production

This study was to investigate the antidiabetic and antihyperlipidemic effects of (E)-3-[3, 4-dihydroxyphenyl-1-(piperidin-1-yl)prop-2-en-1-one] (36-13) (TS), one of caffeic acid amide derivatives, on high-fat (HF-) fed mice. The C57BL/6J mice were randomly divided into the control (CON) group and the experimental group, which was firstly fed a HF diet for 8 weeks. Then, the HF group was subdivided into four groups and was given TS orally (including two doses) or rosiglitazone (Rosi) or vehicle for 4 weeks. Blood, skeletal muscle, and tissues were examined by measuring glycaemia and dyslipidemia-associated events. TS effectively prevented HF diet-induced increases in the levels of blood glucose, triglyceride, insulin, leptin, and free fatty acid (FFA) and weights of visceral fa; moreover, adipocytes in the visceral depots showed a reduction in size. TS treatment significantly increased the protein contents of glucose transporter 4 (GLUT4) in skeletal muscle; TS also significantly enhanced Akt phosphorylation in liver, whereas it reduced the expressions of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). Moreover, TS enhanced phosphorylation of AMP-activated protein kinase (phospho-AMPK) both in skeletal muscle and liver tissue. Therefore, it is possible that the activation of AMPK by TS resulted in enhanced glucose uptake in skeletal muscle, contrasting with diminished gluconeogenesis in liver. TS exhibits hypolipidemic effect by decreasing the expressions of fatty acid synthase (FAS). Thus, antidiabetic properties of TS occurred as a result of decreased hepatic glucose production by PEPCK and G6Pase downregulation and improved insulin sensitization. Thus, amelioration of diabetic and dyslipidemic state by TS in HF-fed mice occurred by regulation of GLUT4, G6Pase, and FAS and phosphorylation of AMPK.

Caffeic acid phenethyl amide ameliorates ischemia/reperfusion injury and cardiac dysfunction in streptozotocin-induced diabetic rats

BACKGROUND

Caffeic acid phenethyl ester (CAPE) has been shown to protect the heart against ischemia/reperfusion (I/R) injury by various mechanisms including its antioxidant effect. In this study, we evaluated the protective effects of a CAPE analog with more structural stability in plasma, caffeic acid phenethyl amide (CAPA), on I/R injury in streptozotocin (STZ)-induced type 1 diabetic rats.

METHODS

Type 1 diabetes mellitus was induced in Sprague-Dawley rats by a single intravenous injection of 60 mg/kg STZ. To produce the I/R injury, the left anterior descending coronary artery was occluded for 45 minutes, followed by 2 hours of reperfusion. CAPA was pretreated intraperitoneally 30 minutes before reperfusion. An analog devoid of the antioxidant property of CAPA, dimethoxyl CAPA (dmCAPA), and a nitric oxide synthase (NOS) inhibitor (Nω-nitro-l-arginine methyl ester [l-NAME]) were used to evaluate the mechanism involved in the reduction of the infarct size following CAPA-treatment. Finally, the cardioprotective effect of chronic treatment of CAPA was analyzed in diabetic rats.

RESULTS

Compared to the control group, CAPA administration (3 and 15 mg/kg) significantly reduced the myocardial infarct size after I/R, while dmCAPA (15 mg/kg) had no cardioprotective effect. Interestingly, pretreatment with a NOS inhibitor, (L-NAME, 3 mg/kg) eliminated the effect of CAPA on myocardial infarction. Additionally, a 4-week CAPA treatment (1 mg/kg, orally, once daily) started 4 weeks after STZ-induction could effectively decrease the infarct size and ameliorate the cardiac dysfunction by pressure-volume loop analysis in STZ-induced diabetic animals.

CONCLUSIONS

CAPA, which is structurally similar to CAPE, exerts cardioprotective activity in I/R injury through its antioxidant property and by preserving nitric oxide levels. On the other hand, chronic CAPA treatment could also ameliorate cardiac dysfunction in diabetic animals.

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.

Caffeic acid phenethyl amide improves glucose homeostasis and attenuates the progression of vascular dysfunction in Streptozotocin-induced diabetic rats

BACKGROUND

Glucose intolerance and cardiovascular complications are major symptoms in patients with diabetes. Many therapies have proven beneficial in treating diabetes in animals by protecting the cardiovascular system and increasing glucose utilization. In this study, we evaluated the effects of caffeic acid phenethyl amide (CAPA) on glucose homeostasis and vascular function in streptozotocin (STZ)-induced type 1 diabetic rats.

METHODS

Diabetes (blood glucose levels > 350 mg/dL), was induced in Wistar rats by a single intravenous injection of 60 mg/kg STZ. Hypoglycemic effects were then assessed in normal and type 1 diabetic rats. In addition, coronary blood flow in Langendorff-perfused hearts was evaluated in the presence or absence of nitric oxide synthase (NOS) inhibitor. The thoracic aorta was used to measure vascular response to phenylephrine. Finally, the effect of chronic treatment of CAPA and insulin on coronary artery flow and vascular response to phenylephrine were analyzed in diabetic rats.

RESULTS

Oral administration of 0.1 mg/kg CAPA decreased plasma glucose in normal (32.9 ± 2.3% decrease, P < 0.05) and diabetic rats (11.8 ± 5.5% decrease, P < 0.05). In normal and diabetic rat hearts, 1-10 μM CAPA increased coronary flow rate, and this increase was abolished by 10 μM NOS inhibitor. In the thoracic aorta, the concentration/response curve of phenylephrine was right-shifted by administration of 100 μM CAPA. Coronary flow rate was reduced to 7.2 ± 0.2 mL/min at 8 weeks after STZ-induction. However, 4 weeks of treatment with CAPA (3 mg/kg, intraperitoneal, twice daily) started at 4 weeks after STZ induction increased flow rate to 11.2 ± 0.5 mL/min (P < 0.05). In addition, the contractile response induced by 1 μM phenylephrine increased from 6.8 ± 0.6 mN to 11.4 ± 0.4 mN (P < 0.05) and 14.9 ± 1.4 mN (P < 0.05) by insulin (1 IU/kg, intraperitoneal) or CAPA treatment, respectively.

CONCLUSIONS

CAPA induced hypoglycemic activity, increased coronary blood flow and vascular response to phenylephrine in type 1 diabetic rats. The increase in coronary blood flow may result from endothelial NOS activation. However, the detailed cellular mechanisms need to be further evaluated.

Hypoglycemic action of borapetoside A from the plant Tinospora crispa in mice

AIM

This study explores the hypoglycemic effects of borapetoside A, the most active principle among three major diterpenoids (borapetosides A, B, and C) isolated from ethanol extract of Tinospora crispa vines.

METHODS

We employed mouse mitogenic C2C12 and hepatocellular carcinoma Hep3B cells in this study. Furthermore, the mice were divided into three groups, including streptozotocin-induced type 1 diabetes mellitus, diet-induced type 2 diabetes mellitus, and normal control. The mice in each group were treated with assigned vehicle control, borapetoside A, or other active agents.

RESULTS

Borapetoside A was shown to increase the glycogen content and decrease the plasma glucose concentration in a concentration or dose-dependent manner in vitro and in vivo. The hypoglycemic effects in the normal mice and the mice with type 2 diabetes mellitus were associated with the increases of the plasma insulin levels; whereas, the insulin levels remained unchanged in the mice with type 1 diabetes mellitus. Borapetoside A not only attenuated the elevation of plasma glucose induced by an intraperitoneal glucose tolerance test, but also increased the glycogen synthesis of IL-6 treated C2C12 cells. Moreover, the elevated protein expression levels of phosphoenolpyruvate carboxykinase were reversed after borapetoside A treatment twice a day for 7 days.

CONCLUSIONS

The hypoglycemic effects of borapetoside A were mediated through both the insulin-dependent and the insulin-independent pathways. Furthermore, borapetoside A was shown to increase the glucose utilization in peripheral tissues, to reduce the hepatic gluconeogenesis, and to activate the insulin signaling pathway; they thereby contributed to the lowering of the plasma glucose. Comparison of the structures of three borapetosides suggests clearly that the C-8 stereochemistry plays a key role in hypoglycemic effect since the active borapetoside A and C possess 8R-chirality but the inactive borapetoside B possess 8S-chirality. The location of glycoside at C-3 for borapetoside A but C-6 for borapetoside C and the formation of lactone between C-4 and C-6 for borapetoside A, could account for the different potency in hypoglycemic action for these two compounds.

Synthesis and antiviral bioactivity of novel (1E, 4E)-1-aryl-5-(2-(quinazolin-4-yloxy)phenyl)-1,4-pentadien-3-one derivatives

A series of novel (1E, 4E)-1-aryl-5-[2-(quinazolin-4-yloxy)phenyl]-1,4-pentadien-3-one derivatives were designed and synthesized by reacting substituent aldehyde with intermediates 4a-f. Antiviral bioassays indicated that most of the compounds exhibited promising ex vivo antiviral bioactivities against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV) at 500 μg/mL. The relationship between structure and antiviral activity was also discussed. Compounds 5a, 6e, and 6g could possess appreciable protective bioactivities on TMV ex vivo by approximately 50% (EC50) at 257.7, 320.7 and 243.3 μg/mL. This study is the first to demonstrate that (1E, 4E)-1-aryl-5-(2-(quinazolin-4-yloxy)phenyl)-1,4-pentadien-3-one can be used to develop potential virucides for plants.

Caffeic Acid Phenylethyl Amide Protects against the Metabolic Consequences in Diabetes Mellitus Induced by Diet and Streptozocin

Caffeic acid phenyl ester is distributed wildly in nature and has antidiabetic and cardiovascular protective effects. However, rapid decomposition by esterase leads to its low bioavailability in vivo. In this study, chronic metabolic and cardiovascular effects of oral caffeic acid phenylethyl amide, whose structure is similar to caffeic acid phenyl ester and resveratrol, were investigated in ICR mice. We found that caffeic acid phenylethyl amide protected against diet or streptozocin-induced metabolic changes increased coronary flow and decreased infarct size after global ischemia-reperfusion in Langendorff perfused heart. Further study indicated that at least two pathways might be involved in such beneficial effects: the induction of the antioxidant protein MnSOD and the decrease of the proinflammatory cytokine TNFα and NFκB in the liver. However, the detailed mechanisms of caffeic acid phenylethyl amide need further studies. In summary, this study demonstrated the protective potential of chronic treatment of caffeic acid phenylethyl amide against the metabolic consequences in diabetes mellitus.

Borapetoside C from Tinospora crispa improves insulin sensitivity in diabetic mice

Diabetes mellitus (DM) often leads to disability from vascular complications and neurological complications. Tinospora crispa has been widely used in Asia and Africa as a remedy for diabetes and other diseases. In this study, we investigated the hypoglycemic actions of borapetoside C isolated from T. crispa, and the mechanisms underlying its actions. Acute treatment with borapetoside C (5mg/kg, i.p.) attenuated the elevated plasma glucose induced by oral glucose in normal and type 2 DM (T2DM) mice. Compared to the effect of injected insulin (0.5 IU/kg), borapetoside C caused a more prominent increase of glycogen content in skeletal muscle of T2DM mice, but a less increase in type 1 DM (T1DM) mice. Combined treatment of a low dose borapetoside C (0.1mg/kg, i.p.) plus insulin enhanced insulin-induced lowering of the plasma glucose level and insulin-induced increase of muscle glycogen content. Continuous treatment with 5mg/kg borapetoside C (twice daily) for 7 days increased phosphorylation of insulin receptor (IR) and protein kinase B (Akt) as well as the expression of glucose transporter-2 (GLUT2) in T1DM mice. Combined treatment of a low dose borapetoside C (0.1mg/kg, twice daily) plus insulin for 7 days enhanced insulin-induced IR and Akt phosphorylation and GLUT2 expression in the liver of T1DM mice. This study proved that borapetoside C can increase glucose utilization, delayed the development of insulin resistance and enhanced insulin sensitivity. The activation of IR-Akt-GLUT2 expression and the enhancement of insulin sensitivity may contribute to the hypoglycemic action of borapetoside C in diabetic mice.

Hypoglycemic diterpenoids from Tinospora crispa

Three new diterpenoids, 2-O-lactoylborapetoside B (1), 6'-O-lactoylborapetoside B (2), and tinocrispol A (3), and nine known diterpenoids (4-12) were isolated from an EtOH extract of Tinospora crispa vines. Their structures were elucidated by spectroscopic analyses. The C-6 glucosyloxy group in borapetoside C (6) was revised to be α-oriented. The in vivo hypoglycemic activities of the major components, borapetosides A-C (4-6), were examined. Intraperitoneal injection of 4 and 6 (5 mg/kg) showed significant lowering of plasma glucose levels in normal and streptozotocin-induced type 1 diabetic mice. Borapetoside C increased glucose utilization in peripheral tissues and reduced hepatic gluconeogenesis, accounting for the hypoglycemic effect.

Rodent models for metabolic syndrome research

Rodents are widely used to mimic human diseases to improve understanding of the causes and progression of disease symptoms and to test potential therapeutic interventions. Chronic diseases such as obesity, diabetes and hypertension, together known as the metabolic syndrome, are causing increasing morbidity and mortality. To control these diseases, research in rodent models that closely mimic the changes in humans is essential. This review will examine the adequacy of the many rodent models of metabolic syndrome to mimic the causes and progression of the disease in humans. The primary criterion will be whether a rodent model initiates all of the signs, especially obesity, diabetes, hypertension and dysfunction of the heart, blood vessels, liver and kidney, primarily by diet since these are the diet-induced signs in humans with metabolic syndrome. We conclude that the model that comes closest to fulfilling this criterion is the high carbohydrate, high fat-fed male rodent.