Exendin‐4 from Heloderma suspectum venom: From discovery to its latest application as type II diabetes combatant

Type II diabetes mellitus (T2DM) is a chronic non‐communicable disease due to abnormal insulin actions causing uncontrolled hyperglycaemia. The treatment for T2DM, for instance, metformin and incretin mimetic, mainly focuses on the restoration of insulin sensitivity and secretion. Exendin‐4 is a short incretin‐mimetic peptide consisting of 39 amino acids. It is discovered in the venom of Heloderma suspectum as a full agonist for the glucagon‐like peptide 1 (GLP‐1) receptor and produces insulinotropic effects. It is more resistant to enzymatic degradation by dipeptidyl‐peptidase‐4 and has a longer half‐life than the endogenous GLP‐1; thus, it is further developed as an incretin hormone analogue used to treat T2DM. The helical region of the peptide first interacts with the extracellular N‐terminal domain (NTD) of GLP‐1 receptor while the C‐terminal extension containing the tryptophan cage further enhances its binding affinity. After binding to the NTD of the receptor, it may cause the receptor to switch from its auto‐inhibited state of the receptor to its auto‐activated state. Exendin‐4 enhances the physiological functions of β‐cells and the up‐regulation of GLP‐1 receptors, thus reducing the plasma glucose levels. Moreover, exendin‐4 has also been found to ameliorate neuropathy, nephropathy and ventricular remodelling. The therapeutic effects of exendin‐4 have also been extrapolated into several clinical trials. Although exendin‐4 has a reasonable subcutaneous bioavailability, its half‐life is rather short. Therefore, several modifications have been undertaken to improve its pharmacokinetics and insulinotropic potency. This review focuses on the pharmacology of exendin‐4 and the structure‐function relationships of exendin‐4 with GLP‐1 receptor. The review also highlights some challenges and future directions in the improvement of exendin‐4 as an anti‐diabetic drug.     

Pharmacokinetic actions of exendin‐4 in the rat: Comparison with glucagon‐like peptide‐1

Exendin‐4, originally isolated from saliva of the lizard Heloderma suspectum, shares 53% sequence homology and several potentially antidiabetic actions with the mammalian hormone glucagon‐like peptide‐1(7‐36)amide (GLP‐1). It shows a higher potency and longer duration of effect in vivo, which may be partly attributed to pharmacokinetic properties. The present study compares the pharmacokinetics of GLP‐1 and exendin‐4 in rats after intravenous (iv), subcutaneous (sc), or intraperitoneal (ip) administration. Samples were assayed for active GLP‐1 (7‐36) amide using an enzyme‐linked immunosorbent assay that does not detect GLP‐1 (1‐36‐amide), (1‐37), (9‐36‐amide) or (9‐37). In parallel experiments, samples were assayed for exendin‐4 using a two‐site immunoradiometric assay that reacts specifically with full‐length exendin‐4. The estimated half‐life for GLP‐1 and exendin‐4 were 0.8–4.7 min and 18–41 min for iv bolus, and 4.6–7.1 min and 90–216 min for SC administration, respectively. Half‐lives after ip injection were 0.6–13.5 min for GLP‐1 and 125–174 min for exendin‐4. Bioavailability for GLP‐1 and exendin‐4 was 44–71% and 65–75%, respectively, for sc injection. For ip injection, bioavailability for GLP‐1 and exendin‐4 was 36–67% and 74–76%, respectively. Plasma clearance, as determined from iv infusion data, was 35–38 ml/min for GLP‐1 and 4‐8 ml/min for exendin‐4. Both Co/C_max and AUC values were proportional to dose with each route of administration. Plasma clearance of exendin‐4 was reduced by 4.4‐fold in nephrectomized animals. In conclusion, exendin‐4 exhibited a much longer plasma half‐life than GLP‐1 in rats after iv, sc, or ip injection, which may contribute in some part to reported differences in duration of biological action of the two peptides. Drug Dev. Res. 53:260–267, 2001. © 2001 Wiley‐Liss, Inc.     

The glucagon‐like peptide‐1 receptor agonist Exendin‐4, ameliorates contrast‐induced nephropathy through suppression of oxidative stress,vascular dysfunction and apoptosis independent of glycaemia

Contrast‐induced nephropathy (CIN) is a leading cause of hospital‐acquired acute kidney injury, particularly in diabetic patients. Previous studies have shown renoprotective effects of glucagon‐like peptide‐1 (GLP‐1) signalling; however, its role in CIN remains unexplored. This study investigates the prophylactic effect of exendin‐4, a GLP‐1R agonist, against CIN in a rat model mimicking both healthy and diabetic conditions. Animals were randomly divided into 7 groups: a control sham group (n = 8), and 2 identical sets of 3 disease groups, one received exendin‐4 before exposure to contrast medium (CM), while the other served as untreated control. The 3 disease groups represented diabetes (n = 8), CIN (n = 8), or diabetes and CIN combined (n = 8). Untreated groups showed deteriorating renal function as indicated by significantly higher levels of serum creatinine and blood urea nitrogen, malondialdehyde, and endothelin‐1 and caspase‐3 expression compared to the sham control group. This was accompanied by a significant decrease in tissue reserves of reduced glutathione, superoxide dismutase, nitrate and endothelin nitric oxide synthase as well as deteriorating renal histology. The CM‐induced changes in diabetic rats indicate impaired renal function, oxidative stress, vascular dysfunction, and apoptosis, and were significance higher in intensity compared to non‐diabetic rats. Pretreatment with exendin‐4 ameliorated all the aforementioned CM‐induced nephropathic effects independent of the glycemic state. To our knowledge, this is the first study describing the prophylactic renoprotective effects of exendin‐4 against CIN. With the current pharmaceutical use of exendin‐4 as a hypoglycaemic agent, the GLP‐1R agonist becomes an interesting candidate for human clinical trials on CIN prevention.     

Preclinical pharmacokinetic and pharmacodynamic evaluation of thiazolidinone PG15: an anti‐inflammatory candidate

Objectives Novel 5‐benzilidene thiazolidinones have been synthesized and exhibited anti‐inflammatory activity. In this work one of the compounds of the thiazolidinone chemical series, (5Z,E)‐3‐[2‐(4‐chlorophenyl)‐2‐oxoethyl]‐5‐(1H‐indol‐3‐ ylmethylene)‐thiazolidine‐2,4‐dione (PG15) was investigated aiming to determine the drug's anti‐inflammatory potential in pre‐clinical studies. Methods Methods used included the in‐vitro inhibition of cyclooxygenase‐1 and ‐2, in‐vivo evaluation of anti‐inflammatory activity by air pouch and peritonitis models and the pharmacokinetic profile after intravenous (3 mg/kg) and oral (3 and 6 mg/kg) dosing to rats. Key findings A two‐compartment model with a fast distribution and an elimination half‐life of 5.9 ± 3.8 h described the PG15 plasma profile after intravenous dosing. PG15 showed an erratic and rapid absorption following oral administration with peak concentrations between 0.5 and 1 h. PG15 0.1 μM inhibited more than 30% and 13% of purified cyclooxygenase‐1 and ‐2 activity in vitro, respectively. A lack of dose dependency was observed for the anti‐inflammatory effect in the dose range investigated (0.8–50 mg/kg), with a maximum of 67.2 ± 4.6% inhibition of leucocyte migration in the carrageenan‐induced air pouch model obtained with the 3 mg/kg dose, similar to that observed for indometacin 10 mg/kg. Conclusions The erratic absorption of PG15 observed after oral dosing could explain the lack of anti‐inflammatory dose dependency.     

Evaluation and in vivo efficacy study of pyrano[3,2‐c]quinoline analogues as TNF‐α inhibitors

A series of pyrano[3,2 c]quinoline was evaluated for its in vivo efficacy as TNF‐α inhibitor using LPS, phosphodiesterase (PDE)‐4, and CIA assays in different mice/rat models. The synthesis was performed using one‐pot multicomponent condensation between 2,4‐dihydroxy‐1‐methylquinoline, malononitrile, and diverse un(substituted) aromatic aldehydes. In vivo efficacy of the title compounds was evaluated using LPS assay in BALB/c mice, PDE4 inhibition in ketamine–xylazine‐induced anesthetize SD rats, and CIA assay was performed in DBA/1J mice as per the standard literature protocols. The outcome of the study revealed that compound 4v was found to be most promising candidate of the series. It was efficacious with 48.8 ± 13.0% inhibition of TNF‐α release at 100 mg/kg p.o., in the LPS assay in Balb/c mice model. It was effective in PDE4 assay in ketamine–xylazine‐induced anesthetize SD rats with duration of 38.3 ± 4.5 min for reversal of anesthetic effect and also showed significant inhibition of PDE4 in salbutamol treated U937 cell assay. It was also abolished TNF‐α induced phosphorylation and degradation of IκBα. Ultimately, its effect on CIA‐related bone and cartilage damage was found statistically similar to Enbrel.     

Anticancer activity using positron emission tomography‐computed tomography and pharmacokinetics of β‐eudesmol in human cholangiocarcinoma xenografted nude mouse model

Cholangiocarcinoma (CCA) is an important public health problem in several parts of South East Asia, particularly in Thailand. The limited availability of effective diagnostic tools for early stage CCA, including chemotherapeutic options, constitutes a major problem for treatment and control of CCA. The aim of the present study was to assess the anti‐CCA activity and pharmacokinetics of β‐eudesmol in CCA‐xenografted nude mouse model and healthy mice. Positron emission tomography‐computed tomography (PET‐CT) with ¹⁸F‐fluorodeoxyglucose was used for detecting and monitoring tumour development, and PET‐CT with technetium‐99m was used to investigate its pharmacokinetics property. Results support the role of PET‐CT as a potential tool for detecting and monitoring the progress of lung metastasis. Tumour size and lung metastasis were significantly inhibited by 91.6% (of baseline) and 95% (of total lung mass), respectively, following treatment with high‐dose β‐eudesmol (100 mg/kg body weight for 30 days). Survival time was prolonged by 64.4% compared with untreated controls. Systemic clearance of the compound was rapid, particularly during the first 60 min. The compound was distributed to the vital organs at maximum levels 2 h after oral administration and 15 min after intravenous injection. Results from the present study suggest the potential of β‐eudesmol as a promising candidate for further development as an anti‐CCA drug with respect to its pharmacodynamics and pharmacokinetic properties. PET‐CT, with radiotracers ¹⁸F‐fluorodeoxyglucose and technetium‐99m, was shown to be a reliable tool in the investigation of anti‐CCA and pharmacokinetic properties of β‐eudesmol in CCA‐xenografted and healthy mice.     

Effect of dimethylnitrosamine‐induced liver dysfunction on the pharmacokinetics of 5‐fluorouracil after administration of S‐1, an antitumour drug,to rats

Objectives The anti‐tumour agent S‐1 comprises tegafur (a prodrug of 5‐fluorouracil; 5‐FU), gimeracil (2‐chloro‐2,4‐dihydroxypyridine (CDHP); a competitive inhibitor of 5‐FU metabolism) and oteracil potassium. The effect of hepatic dysfunction induced by dimethylnitrosamine (DMN) on the pharmacokinetics of 5‐FU after administration of S‐1 to rats was investigated. Methods S‐1 (5 mg/kg) was administered intravenously and orally to rats with DMN‐induced liver dysfunction. Plasma concentrations of S‐1 components and 5‐FU were measured by HPLC and LC/MS‐MS. Blood tests and in‐vitro enzymatic investigations were also conducted. Key findings DMN treatment induced hepatic dysfunction and decreased the conversion of tegafur to 5‐FU in the liver without altering renal function or dihydropyrimidine dehydrogenase activity. Following intravenous administration of S‐1, the blood concentration‐time profiles of CDHP were similar between control rats and rats with hepatic dysfunction, but the half‐life of tegafur was significantly prolonged. The maximum plasma concentration (C_max) of 5‐FU was significantly reduced and the area under the blood concentration‐time curve (AUC) was reduced by 22%. Following oral administration, the C_max of tegafur, 5‐FU and CDHP were significantly decreased and half‐lives significantly increased. Hepatic dysfunction had a less pronounced effect on the AUC of 5‐FU (13.6% reduction). Conclusions The pharmacokinetic profiles of tegafur, 5‐FU and CDHP were altered by changes in the elimination rate of tegafur induced by a decrease in the conversion of tegafur to 5‐FU. However, hepatic dysfunction had less of an effect on the AUC of 5‐FU, which correlates with anti‐tumour effect, after the oral administration of S‐1.     

Pharmacokinetics and tissue distribution of 3,4‐diaminopyridine in rats

Lambert‐Eaton myasthenic syndrome (LEMS) is characterized by muscle weakness, amyotrophy, easy fatigability, and depressed tendon reflexes. 3,4‐Diaminopyridine (3,4‐DAP) is the recommended therapy for the treatment of LEMS. However, estimations of 3,4‐DAP pharmacokinetics in human and animals, such as rats, are rarely reported because 3,4‐DAP is an orphan drug for the treatment of a very rare disease (LEMS). In particular, little is known about its tissue distribution. Therefore, the pharmacokinetics of 3,4‐DAP were studied, with particular focus on tissue distribution, in rats. After intravenous administration of 3,4‐DAP to rats, the half‐life of 3,4‐DAP was 15.9 ± 3.9 min and the volume of distribution at steady‐state was 2.8 ± 0.7 L/kg. The tissue‐to‐plasma partition coefficient (Kp) was high in the kidney, heart, and muscle. In addition, with increased steady state plasma concentration (Css), a tendency toward increased Kp was found in most tissues. In the muscle, a likely target region of 3,4‐DAP in LEMS patients, the Kp was higher than in the plasma. Furthermore, more than 68% of 3,4‐DAP was distributed to the muscle as determined by the ratio of 3,4‐DAP distribution calculated from the apparent volumes of distribution. Hence, 3,4‐DAP may provide for more effective and long‐lasting effects.     

Synthesis and pharmacological evaluation of 3‐(4‐chloro phenyl)‐2‐substituted‐3H‐quinazolin‐4‐ones as analgesic and anti‐inflammatory agents

A new series of 3‐(4‐chloro phenyl)‐2‐substituted‐3H‐quinazolin‐4‐ones were synthesized by reacting the amino group of 2‐hydrazino‐3‐(4‐chloro phenyl)‐3H‐quinazolin‐4‐one with different aldehydes and ketones. The compounds were investigated for their analgesic activity in albino mice, and for their anti‐inflammatory and ulcerogenic activities in Wistar rats. All test compounds exhibited analgesic and anti‐inflammatory activities. Compound VA2 (2‐(1‐ethylpropylidene‐hydrazino)‐3‐(4‐chloro phenyl)‐3H‐quinazolin‐4‐one) showed moderately more potent analgesic activity and compound VA3 (2‐(1‐methylbutylidene‐hydrazino)‐3‐(4‐chlorophenyl)‐3H‐quinazolin‐4‐one) showed moderately more potent anti‐inflammatory activity when compared with the reference standard, diclofenac sodium. The test compounds showed only mild ulcerogenic side effects when compared with aspirin. Drug Dev Res 69: 226–233, 2008 ©2008 Wiley‐Liss, Inc.     

Binding to dipeptidyl peptidase‐4 determines the disposition of linagliptin (BI 1356) – investigations in DPP‐4 deficient and wildtype rats

Linagliptin (BI 1356) is a novel dipeptidyl peptidase‐4 (DPP‐4) inhibitor in clinical development for the treatment of type 2 diabetes. It exhibits non‐linear pharmacokinetics and shows concentration‐dependent plasma protein binding to its target, DPP‐4. The aim of this study was to investigate the impact of saturable binding of linagliptin to plasma and tissue DPP‐4 by comparing the pharmacokinetics of linagliptin in wildtype and DPP‐4 deficient Fischer rats using non‐compartmental and model‐based data analysis. The non‐compartmental analysis revealed a significantly reduced AUC in DPP‐4 deficient rats compared with wildtype rats when single intravenous doses ?1 mg/kg were administered, but the exposure was similar in both strains at higher doses. The terminal half‐lives were significantly shorter in DPP‐4 deficient rats compared with wildtype rats. For doses ?1 mg/kg, DPP‐4 deficient rats exhibited linear pharmacokinetics, whereas the pharmacokinetics of wildtype rats was non‐linear. In the model‐based analysis these differences could be accounted for by assuming concentration‐dependent protein binding in the central and one peripheral compartment in wildtype rats. In the model, disposition parameters for unbound linagliptin were assumed to be identical in both rat strains. Simulations with different doses of linagliptin and different concentrations of binding sites further illustrated that the interdependence of linagliptin and DPP‐4 in plasma and in the periphery has a major influence on the disposition of linagliptin in wildtype rats. In conclusion, the study showed that the concentration‐dependent binding of linagliptin to its target DPP‐4 has a major impact on the plasma pharmacokinetics of linagliptin. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and Biological Evaluation of 3, 8‐dimethyl‐5‐isopropylazulene Derivatives as Anti‐gastric Ulcer Agent

Recent studies showed that Guaiazulene (GA) and Sodium guaiazulene sulfonate (GAS‐Na) have good anti‐gastric ulcer effect. Here, two series of GA derivatives were synthesized and evaluated for their anti‐gastric ulcer activity. The data obtained from in vivo testing of these compounds in a rodent ethanol‐induced stomach injury model are discussed. Among the tested compounds, A1 , A4 , and A9 (ulcer index: 1.125 ± 1.246**, 1.714 ± 0.756*, 1.875 ± 1.126*) exhibited better anti‐gastric ulcer activity than the positive control Omeprazole (2.005 ± 1.011*). The information got from these studies and the results of 3D‐SAR investigation may be useful in the design of novel anti‐gastric ulcer agents.     

Anti‐inflammatory properties of resveratrol in the retinas of type 2 diabetic rats

Resveratrol (trans‐3,5,4′‐trihydroxystilbene) is a nutritional supplement with anti‐inflammatory properties. The present study investigated the long‐term anti‐inflammatory property of resveratrol in the retinas of type 2 diabetic rats. Male Wistar rats were divided into four groups: normal control, diabetic control, resveratrol‐treated normal rats and resveratrol‐treated diabetic rats. Type 2 diabetes was induced by a single dose injection of streptozotocin (50 mg/kg; i.p.) 15 min after the administration of nicotinamide (110 mg/kg; i.p.) in 12‐h fasted rats (the streptozotocin–nicotinamide type 2 diabetic model). Oral resveratrol administration (5 mg/kg per day for 4 months) significantly improved glucose tolerance, and alleviated hyperglycemia and weight loss in diabetic rats. Furthermore, resveratrol administration significantly decreased the elevated levels of nuclear factor‐κB activity, and mRNA expression, tumour necrosis factor alpha level and apoptotic cells in the retinas of the diabetic rats. Furthermore, resveratrol did not significantly affect plasma insulin levels. Long‐term resveratrol administration has beneficial anti‐inflammatory properties in a rat model of diabetes. However, whether resveratrol exerts its effects directly or through reducing blood glucose levels requires further investigation.     

Development of a mono‐specific anti‐VEGF bivalent nanobody with extended plasma half‐life for treatment of pathologic neovascularization

Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis within solid cancers. Thus, targeting VEGF might be part of a feasible therapy for treating pathological neovascularization, and nanobodies ? derived from heavy chain‐only antibodies occurring within Camelidae ? are a novel class of nanometer‐sized antibodies possessing unique properties that could be developed into a promising therapeutic. However, nanobodies have a very short half‐life in vivo due to their small size. Development of a bivalent nanobody is one way to remediate the half‐life problem of nanobodies. Two identical anti‐VEGF nanobodies were connected using the hinge region of llama IgG2c. The recombinant plasmid (pHEN6c‐bivalent nanobody) was transformed into E.coli WK6 cells and expression of the bivalent nanobody construct was induced with 1mM Isopropyl β‐D‐1‐thiogalactopyranoside (IPTG). Recombinant bivalent nanobody was purified using nickel affinity chromatography and its activity on human endothelial cells was assessed using 3‐(4,5‐Dimethylthiazol‐2‐yr)‐2,5‐diphenyltetrazolium bromide (MTT), tube formation, and cell migration assays. The pharmacokinetic study was performed after intravenous (i.v.) injection of recombinant bivalent nanobody into six‐week‐old C57BL/6 mice. Recombinant bivalent nanobody performed significantly better than monovalent nanobody in inhibiting proliferation, tube formation, and migration of human endothelial cells. Pharmacokinetic results showed a 1.8‐fold longer half‐life of bivalent nanobody in comparison with the monovalent nanobody. These results underscore the potential of recombinant anti‐VEGF bivalent nanobody as a promising tool for development of a novel therapeutic with an extended plasma half‐life for VEGF‐related diseases.     

Curcumin‐loaded poly(ε‐caprolactone) nanofibres: Diabetic wound dressing with anti‐oxidant and anti‐inflammatory properties

• 1 Curcumin is a naturally occurring poly‐phenolic compound with a broad range of favourable biological functions, including anti‐cancer, anti‐oxidant and anti‐inflammatory activities. The low bioavailability and in vivo stability of curcumin require the development of suitable carrier vehicles to deliver the molecule in a sustained manner at therapeutic levels.
• 2 In the present study, we investigated the feasibility and potential of poly(caprolactone) (PCL) nanofibres as a delivery vehicle for curcumin for wound healing applications. By optimizing the electrospinning parameters, bead‐free curcumin‐loaded PCL nanofibres were developed.
• 3 The fibres showed sustained release of curcumin for 72 h and could be made to deliver a dose much lower than the reported cytotoxic concentration while remaining bioactive. Human foreskin fibroblast cells (HFF‐1) showed more than 70% viability on curcumin‐loaded nanofibres.
• 4 The anti‐oxidant activity of curcumin‐loaded nanofibres was demonstrated using an oxygen radical absorbance capacity (ORAC) assay and by the ability of the fibres to maintain the viability of HFF‐1 cells under conditions of oxidative stress.
• 5 The curcumin‐loaded nanofibres also reduced inflammatory induction, as evidenced by low levels of interleukin‐6 release from mouse monocyte–macrophages seeded onto the fibres following stimulation by Escherichia coli‐derived lipopolysaccharide.
• 6 The in vivo wound healing capability of the curcumin loaded PCL nanofibres was demonstrated by an increased rate of wound closure in a streptozotocin‐induced diabetic mice model.
• 7 These results demonstrate that the curcumin‐loaded PCL nanofibre matrix is bioactive and has potential as a wound dressing with anti‐oxidant and anti‐inflammatory properties.

     

99mTc‐labeled NGR‐chlorambucil conjugate, 99mTc‐HYNIC‐CLB‐c(NGR) for targeted chemotherapy and molecular imaging

Targeted delivery of chemotherapeutic drug at the tumor site enhances the efficacy with minimum systemic exposure. Towards this, drugs conjugated with peptides having affinity towards a particular molecular target are recognized as affective agents for targeted chemotherapy. Thus, in the present study, tumor‐homing asparagine‐glycine‐arginine (NGR) peptide ligand was conjugated to DNA alkylating nitrogen mustard, chlorambucil (CLB). The peptide‐drug conjugate (PDC), CLB‐c(NGR), was radiolabeled with ^99mTc‐HYNIC core to trace its pharmacokinetics and biodistribution pattern. In vitro cell‐binding studies of ^99mTc‐HYNIC‐CLB‐c(NGR) were conducted in murine melanoma B16F10 cells. The cytotoxicity studies conducted by incubation of the peptide/drug/PDC with B16F10 cells demonstrated enhanced cytotoxic effect of PDC in comparison to either the peptide or the drug alone. In vivo biodistribution studies in C57BL6 mice bearing melanoma tumor showed maximum tumor uptake at 30 minutes pi (2.45 ± 0.28% ID/g), which reduced to 0.77 ± 0.1% ID /g at 3 hours pi. The radiotracer being hydrophilic cleared rapidly from the heart, lungs, liver, and muscle. The tumor‐to‐blood and tumor‐to‐muscle ratios improved with time. This study opens avenues for conjugation of other targeting peptides with the drug CLB for enhanced toxicity at the diseased site.     

3‐Acetyl‐11‐keto‐β‐boswellic acid loaded‐polymeric nanomicelles for topical anti‐inflammatory and anti‐arthritic activity

Objectives The aim of this study was to develop 3‐acetyl‐11‐keto‐β‐boswellic acid (AKBA)‐loaded polymeric nanomicelles for topical anti‐inflammatory and anti‐arthritic activity. Methods Polymeric nanomicelles of AKBA were developed by a radical polymerization method using N‐isopropylacrylamide, vinylpyrrolidone and acrylic acid. The polymeric nanomicelles obtained were characterized by Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). In‐vitro and in‐vivo evaluations of AKBA polymeric nanomicelles gel were carried out for enhanced skin permeability and anti‐inflammatory and anti‐arthritic activity. Key findings TEM and DLS results demonstrated that polymeric nanomicelles were spherical with a mean diameter approximately 45 nm. FTIR data indicated a weak interaction between polymer and AKBA in the encapsulated system. The release of drug in aqueous buffer (pH 7.4) from the polymeric nanomicelles was 23 and 55% after 2 and 8 h, respectively, indicating sustained release. In‐vitro skin permeation studies through excised abdominal skin indicated a threefold increase in skin permeability compared with AKBA gel containing the same amount of AKBA as the AKBA polymeric nanomicelles gel. The AKBA polymeric nanomicelle gel showed significantly enhanced anti‐inflammatory and anti‐arthritic activity compared with the AKBA gel. Conclusions This study suggested that AKBA polymeric nanomicelle gel significantly enhanced skin permeability, and anti‐inflammatory and anti‐arthritic activity.     

4‐Phenyl butyric acid does not generally reduce glucose levels in rodent models of diabetes

1. Endoplasmic reticulum (ER) stress plays a role in the pathogenesis of diabetes. The aim of the present study was to investigate the effect of 4‐phenyl butyric acid (PBA), a novel chemical chaperone reducing ER stress, on serum glucose level in different strains of normal and diabetic rodents. 2. 4‐Phenyl butyric acid (1 g/kg per day, i.g.) was administered to ob/ob Type 2 diabetic mice, alloxan‐induced Type 1 diabetic mice and hydrocortisone (HC)‐induced Type 2 diabetic mice as well as normal C57BL/6J mice and Kumming mice for 14 days to evaluate its effect on serum glucose levels. In addition, mice were treated simultaneously with PBA (1 g/kg per day) and HC for 9 days to determine its preventive effect against the development of insulin resistance. PBA (0.7 and 1.4 g/kg per day) was administered to non‐obese Type 2 diabetic Goto‐Kakizaki (GK) and normal Wistar‐Kyoto (WKY) rats for 14 and 7 days, respectively, to determine its effects on serum glucose levels. 3. 4‐Phenyl butyric acid significantly reduced serum glucose levels in obese Type 2 diabetic ob/ob mice. Normoglycaemia was obtained in ob/ob mice after 4 days of PBA treatment and was maintained for up to 14 days treatment. 4. 4‐Phenyl butyric acid had no glucose‐lowering effect in alloxan‐induced Type 1 diabetic mice, HC‐induced Type 2 diabetic mice and non‐obese Type 2 diabetic GK rats. In addition, it had no beneficial effects on insulin resistance in HC‐treated mice. 5. 4‐Phenyl butyric acid did not affect normal serum glucose levels in C57BL/6 J mice, Kunming mice or WKY rats. 6. In conclusion, PBA does not generally reduce glucose levels in rodent models of diabetes, although it can normalize glucose levels in ob/ob diabetic mice, indicating that restoration of ER function as diabetes therapy is limited to conditions under which ER stress is involved in the high glucose levels.     

New biological investigations on 3‐bromophenyl 6‐acetoxymethyl‐2‐oxo‐2H‐1‐benzopyran‐3‐carboxylate as anti‐angiogenic agent

The development of blood vessels inside tumors is required to provide the nutrients and oxygen needed for tumor growth and to allow the spread of cancer cells at a distance to form metastasis. Angiogenesis is also implicated in ocular diseases like age‐related macular degeneration. The present work describes the potential anti‐angiogenic properties of a coumarinic derivative, 3‐bromophenyl 6‐acetoxymethyl‐2‐oxo‐2H‐1‐benzopyran‐3‐carboxylate (IK9), previously described as a potent inhibitor of HT 1080 fibrosarcoma cell invasion in vitro and tumor growth in vivo. In vivo, ex vivo, and in vitro models were used to delineate the anti‐angiogenic properties of IK9. The anti‐angiogenic effect of IK9 was demonstrated in vivo in a choroidal neovascularization mice model and additionally ex vivo in a rat aortic ring assay where it was more active than the known matrix metalloproteinase inhibitor Ro 28‐2653. IK9 did not affect apoptosis, proliferation, or endothelial cell invasiveness in vitro. These findings suggest a complex mechanism of action of the compound via direct or indirect effects on endothelial cell properties. This study identifies IK9 as a new potent inhibitor of angiogenesis and suggests its potential use as a therapeutic agent. Drug Dev Res 71, 2010. © 2010 Wiley‐Liss, Inc.