Oleanolic acid derivative NPLC441 potently stimulates glucose transport in 3T3-L1 adipocytes via a multi-target mechanism

Overview of Ursolic Acid Potential for the Treatment of Metabolic Disorders, Autoimmune Diseases, and Cancers via Nuclear Receptor Pathways

Nuclear receptors (NRs) form a family of druggable transcription factors that are regulated by ligand binding to orchestrate multifaceted physiological functions, including reproduction, immunity, metabolism, and growth. NRs represent attractive and valid targets for the management and treatment of a vast array of ailments. Pentacyclic triterpenes (PTs) are ubiquitously distributed natural products in medicinal and aromatic plants, of which ursolic acid (UA) is an extensively studied member, due to its diverse bio-pertinent activities against different cancers, inflammation, aging, obesity, diabetes, dyslipidemia, and liver injury. In fact, PTs share a common lipophilic structure that resembles NRs' endogenous ligands. Herein, we present a review of the literature on UA's effect on NRs, showcasing the resulting health benefits and potential therapeutic outcomes. De facto, UA exhibited numerous pharmacodynamic effects on PPAR, LXR, FXR, and PXR, resulting in remarkable anti-inflammatory, anti-hyperlipidemic, and hepatoprotective properties, by lowering lipid accumulation in hepatocytes and mitigating non-alcoholic steatohepatitis (NASH) and its subsequent liver fibrosis. Furthermore, UA reversed valproate and rifampicin-induced hepatic lipid accumulation. Additionally, UA showed great promise for the treatment of autoimmune inflammatory diseases such as multiple sclerosis and autoimmune arthritis by antagonizing RORγ. UA exhibited antiproliferative effects against skin, prostate, and breast cancers, partially via PPARα and RORγ pathways. Herein, for the first time, we explore and provide insights into UA bioactivity with respect to NR modulation.

Harnessing Oleanolic Acid and Its Derivatives as Modulators of Metabolic Nuclear Receptors

Nuclear receptors (NRs) constitute a superfamily of ligand-activated transcription factors with a paramount role in ubiquitous physiological functions such as metabolism, growth, and reproduction. Owing to their physiological role and druggability, NRs are deemed attractive and valid targets for medicinal chemists. Pentacyclic triterpenes (PTs) represent one of the most important phytochemical classes present in higher plants, where oleanolic acid (OA) is the most studied PTs representative owing to its multitude of biological activities against cancer, inflammation, diabetes, and liver injury. PTs possess a lipophilic skeleton that imitates the NRs endogenous ligands. Herein, we report a literature overview on the modulation of metabolic NRs by OA and its semi-synthetic derivatives, highlighting their health benefits and potential therapeutic applications. Indeed, OA exhibited varying pharmacological effects on FXR, PPAR, LXR, RXR, PXR, and ROR in a tissue-specific manner. Owing to these NRs modulation, OA showed prominent hepatoprotective properties comparable to ursodeoxycholic acid (UDCA) in a bile duct ligation mice model and antiatherosclerosis effect as simvastatin in a model of New Zealand white (NZW) rabbits. It also demonstrated a great promise in alleviating non-alcoholic steatohepatitis (NASH) and liver fibrosis, attenuated alpha-naphthol isothiocyanate (ANIT)-induced cholestatic liver injury, and controlled blood glucose levels, making it a key player in the therapy of metabolic diseases. We also compiled OA semi-synthetic derivatives and explored their synthetic pathways and pharmacological effects on NRs, showcasing their structure-activity relationship (SAR). To the best of our knowledge, this is the first review article to highlight OA activity in terms of NRs modulation.

Identification of small-molecule inhibitors of the DNA repair proteins RuvAB from Pseudomonas aeruginosa

The Holliday junction (HJ) branch migrator RuvAB complex plays a fundamental role during homologous recombination and DNA damage repair, and therefore, is an attractive target for the treatment of bacterial pathogens. Pseudomonas aeruginosa (P. aeruginosa, Pa) is one of the most common clinical opportunistic bacterial pathogens, which can cause a series of life-threatening acute or chronic infections. Here, we performed a high throughput small-molecule screening targeting PaRuvAB using the FRET-based HJ branch migration assay. We identified that corilagin, bardoxolone methyl (BM) and 10-(6'-plastoquinonyl) decyltriphenylphosphonium (SKQ1) could efficiently inhibit the branch migration activity of PaRuvAB, with IC₅₀ values of 0.40 ± 0.04 μM, 0.38 ± 0.05 μM and 4.64 ± 0.27 μM, respectively. Further biochemical and molecular docking analyses demonstrated that corilagin directly bound to PaRuvB at the ATPase domain, and thus prevented ATP hydrolysis. In contrast, BM and SKQ1 acted through blocking the interactions between PaRuvA and HJ DNA. Finally, these compounds were shown to increase the susceptibility of P. aeruginosa to UV-C irradiation. Our work, for the first time, reports the small-molecule inhibitors of RuvA and RuvB from any species, providing valuable chemical tools to dissect the functional role of each individual protein in vivo.

Bredemolic acid restores glucose utilization and attenuates oxidative stress in palmitic acid-induced insulin-resistant C2C12 cells

Objective. Due to insulin resistance and oxidative stress that are associated with type 2 diabetes mellitus (T2DM), T2DM has become a prevalent metabolic disorder that presents various side effects. However, alternative antidiabetic treatment has commonly been used in treating diabetes mellitus in diabetic patients. In our previous studies, bredemolic acid has been reported as an antidiabetic agent that improves glucose uptake, ameliorates insulin resistance, and oxidative stress in the liver, heart, kidney, and skeletal muscle of prediabetic rats. However, these effects have not been validated in vitro. Therefore, this study was aimed to investigate the effects of bredemolic acid on insulin-mediated glucose utilization, lipid peroxidation, and the total antioxidant capacity (TOAC) in palmitic acid-induced insulin-resistant C2C12 skeletal muscle cells in vitro. Methods. Insulin resistance was induced in the skeletal muscle cells after 4 h of exposure to palmitic acid (0.5 mmol/l). Different cell groups were incubated in culture media DMEM supplemented with fetal calf serum (10%), penicillin/streptomycin (1%), and L-glutamine (1%) and then treated with either insulin (4 µg/ml) or bredemolic acid (12.5 mmol/l) or with both. Thereafter, the cells were seeded in 24- or 96-well plates for determination of the cell viability, glucose utilization, glycogen formation, and antioxidant capacity. Results. The results showed that bredemolic acid significantly improved TOAC and promoted glucose utilization via attenuation of lipid peroxidation and increased glycogen formation in the insulin-resistant cells, respectively. Conclusion. This study showed that bredemolic acid restored the insulin resistance through improved glucose utilization, glycogen formation, and TOAC in the skeletal muscle cells.

Molecular Mechanisms Underlying the Effects of Olive Oil Triterpenic Acids in Obesity and Related Diseases

Dietary components exert protective effects against obesity and related metabolic and cardiovascular disturbances by interfering with the molecular pathways leading to these pathologies. Dietary biomolecules are currently promising strategies to help in the management of obesity and metabolic syndrome, which are still unmet medical issues. Olive oil, a key component of the Mediterranean diet, provides an exceptional lipid matrix highly rich in bioactive molecules. Among them, the pentacyclic triterpenic acids (i.e., oleanolic acid) have gained clinical relevance in the last decade due to their wide range of biological actions, particularly in terms of vascular function, obesity and insulin resistance. Considering the promising effects of these triterpenic compounds as nutraceuticals and components of functional foods against obesity and associated complications, the aim of our review is to decipher and discuss the main molecular mechanisms underlying these effects driven by olive oil triterpenes, in particular by oleanolic acid. Special attention is paid to their signaling and targets related to glucose and insulin homeostasis, lipid metabolism, adiposity and cardiovascular dysfunction in obesity. Our study is aimed at providing a better understanding of the impact of dietary components of olive oil in the long-term management of obesity and metabolic syndrome in humans.

ABCA1 Variants rs1800977 (C69T) and rs9282541 (R230C) Are Associated with Susceptibility to Type 2 Diabetes

OBJECTIVE

Accumulated evidence suggests that ATP-binding cassette A1 transporter (ABCA1) contributes to secreting insulin in pancreatic β-cells and amyloid beta formation. This study aimed to investigate the association between three single nucleotide polymorphisms (SNPs) of ABCA1 and susceptibility to type 2 diabetes mellitus (T2DM) in a Han Chinese population.

METHODS

A total of 996 T2DM patients and 1,002 controls were included in the study. Three SNPs in the ABCA1 gene, i.e., rs2230806 (R219K), rs1800977 (C69T), and rs9282541 (R230C), were genotyped by SNaPshot. A genotype model, an allele model, a dominant model, and a recessive model were used to assess susceptibility to T2DM.

RESULTS

There were significant associations between rs1800977 and T2DM in different genetic models (TT vs. CC, OR = 0.591 [0.446-0.793], p < 0.001; T vs. C, OR = 0.835 [0.735-0.949], p = 0.006; recessive model, OR = 0.583 [0.449-0.756], p < 0.001). There were also significant associations between rs9282541 and T2DM in different genetic models (CT vs. CC, OR = 1.690 [0.807-1.005], p = 0.048; T vs. C, OR = 1.756 [0.694-1.060], p = 0.029; dominant model, OR = 1.735 [0.715-1.034], p = 0.037).

CONCLUSION

Our case-control study showed that the two SNPs rs1800977 and rs9282541 in the ABCA1 gene are significantly associated with susceptibility to T2DM in our Han Chinese population. Study of further mechanisms should be performed before application to clinical therapy.

Ursolic Acid and Chronic Disease: An Overview of UA's Effects On Prevention and Treatment of Obesity and Cancer

Chronic diseases pose a worldwide problem and are only continuing to increase in incidence. Two major factors contributing to the increased incidence in chronic disease are a lack of physical activity and poor diet. As the link between diet and lifestyle and the increased incidence of chronic disease has been well established in the literature, novel preventive, and therapeutic methods should be aimed at naturally derived compounds such as ursolic acid (UA), the focus of this chapter. As chronic diseases, obesity and cancer share the common thread of inflammation and dysregulation of many related pathways, the focus here will be on these two chronic diseases. Significant evidence in the literature supports an important role for natural compounds such as UA in the prevention and treatment of chronic diseases like obesity and cancer, and here we have highlighted many of the ways UA has been shown to be a beneficial and versatile phytochemical.

Discovery of Farnesoid X Receptor Antagonists Based on a Library of Oleanolic Acid 3-O-Esters through Diverse Substituent Design and Molecular Docking Methods

The pentacyclic triterpene oleanolic acid (OA, 1) with known farnesoid X receptor (FXR) modulatory activity was modified at its C-3 position to find new FXR-interacting agents. A diverse substitution library of OA derivatives was constructed in silico through a 2D fingerprint similarity cluster strategy. With further docking analysis, four top-scored OA 3-O-ester derivatives were selected for synthesis. The bioassay results indicated that all four compounds 3 inhibited chenodeoxycholic acid (CDCA)-induced FXR transactivation in a concentration-dependent mode. Among them 3b and 3d are more active than the parent compound OA. A molecular simulation study was performed to attempt to explain the structure-activity relationship (SAR) and the antagonistic action. To the best of our knowledge, this is the first report on semi-synthetic pentacyclic triterpenoids with FXR-modulatory activities.

Synthesis and Cytotoxic Activity of Triterpenoid Thiazoles Derived from Allobetulin, Methyl Betulonate, Methyl Oleanonate, and Oleanonic Acid

A total of 41 new triterpenoids were prepared from allobetulone, methyl betulonate, methyl oleanonate, and oleanonic acid to study their influence on cancer cells. Each 3-oxotriterpene was brominated at C2 and substituted with thiocyanate; subsequent cyclization with the appropriate ammonium salts gave N-substituted thiazoles. All compounds were tested for their in vitro cytotoxic activity on eight cancer cell lines and two non-cancer fibroblasts. 2-Bromoallobetulone (2 b) methyl 2-bromobetulonate (3 b), 2-bromooleanonic acid (5 b), and 2-thiocyanooleanonic acid (5 c) were best, with IC₅₀ values less than 10 μm against CCRF-CEM cells (e.g., 3 b: IC₅₀ =2.9 μm) as well as 2'-(diethylamino)olean-12(13)-eno[2,3-d]thiazole-28-oic acid (5 f, IC₅₀ =9.7 μm) and 2'-(N-methylpiperazino)olean-12(13)-eno[2,3-d]thiazole-28-oic acid (5 k, IC₅₀ =11.4 μm). Compound 5 c leads to the accumulation of cells in the G₂ phase of the cell cycle and inhibits RNA and DNA synthesis significantly at 1×IC₅₀ . The G₂ /M cell-cycle arrest probably corresponds to the inhibition of DNA/RNA synthesis, similar to the mechanism of action of actinomycin D. Compound 5 c is new, active, and nontoxic; it is therefore the most promising compound in this series for future drug development. Methyl 2-bromobetulonate (3 b) and methyl 2-thiocyanometulonate (3 c) were found to inhibit nucleic acid synthesis only at 5×IC₅₀ . We assume that in 3 b and 3 c (unlike in 5 c), DNA/RNA inhibition is a nonspecific event, and an unknown primary cytotoxic target is activated at 1×IC₅₀ or lower concentration.

Bardoxolone methyl prevents obesity and hypothalamic dysfunction

High-fat (HF) diet-induced obesity is associated with hypothalamic leptin resistance and low grade chronic inflammation, which largely impairs the neuroregulation of negative energy balance. Neuroregulation of negative energy balance is largely controlled by the mediobasal and paraventricular nuclei regions of the hypothalamus via leptin signal transduction. Recently, a derivative of oleanolic acid, bardoxolone methyl (BM), has been shown to have anti-inflammatory effects. We tested the hypothesis that BM would prevent HF diet-induced obesity, hypothalamic leptin resistance, and inflammation in mice fed a HF diet. Oral administration of BM via drinking water (10 mg/kg daily) for 21 weeks significantly prevented an increase in body weight, energy intake, hyperleptinemia, and peripheral fat accumulation in mice fed a HF diet. Furthermore, BM treatment prevented HF diet-induced decreases in the anorexigenic effects of peripheral leptin administration. In the mediobasal and paraventricular nuclei regions of the hypothalamus, BM administration prevented HF diet-induced impairments of the downstream protein kinase b (Akt) pathway of hypothalamic leptin signalling. BM treatment also prevented an increase in inflammatory cytokines, tumour necrosis factor alpha (TNFα) and interleukin 6 (IL-6) in these two hypothalamic regions. These results identify a potential novel neuropharmacological application for BM in preventing HF diet-induced obesity, hypothalamic leptin resistance, and inflammation.

Oleanolic acid derivatives for pharmaceutical use: a patent review

INTRODUCTION

Oleanolic acid belongs to the pentacyclic triterpene family. In China, oleanolic acid has been used as an over the counter (OTC) hepatoprotective drug for decades. Oleanolic acid and its derivatives present a wide variety of biological activities, supporting their pharmaceutical uses for multiple diseases.

AREAS COVERED

Representative patent publications (1971-2015) covering the preparation, pharmaceutical compositions, and medical uses of oleanolic acid and its derivatives are analyzed, with focus on their anticancer, anti-osteoporosis, anti-obesity, anti-diabetic, lipid-lowering, anti-inflammatory, antioxidant, immune-regulatory, and hepatoprotective effects. A large number of Chinese patents have been given particular attention in this review.

EXPERT OPINION

Detailed efficacy studies are highly worth doing to undoubtedly confirm the clinical potential of oleanolic acid and its derivatives. Based on that, it would be critical to identify the key protein targets of the drugs so as to promote drug development and search for new lead compounds. Together, there is a huge potential for drug-repositioning of oleanolic acid, particularly in the areas of metabolic disease and immunological disorders.

Oleanolic Acid Induces Differentiation of Neural Stem Cells to Neurons: An Involvement of Transcription Factor Nkx-2.5

Neural stem cells (NSCs) harbor the potential to differentiate into neurons, astrocytes, and oligodendrocytes under normal conditions and/or in response to tissue damage. NSCs open a new way of treatment of the injured central nervous system and neurodegenerative disorders. Thus far, few drugs have been developed for controlling NSC functions. Here, the effect as well as mechanism of oleanolic acid (OA), a pentacyclic triterpenoid, on NSC function was investigated. We found OA significantly inhibited neurosphere formation in a dose-dependent manner and achieved a maximum effect at 10 nM. OA also reduced 5-ethynyl-2'-deoxyuridine (EdU) incorporation into NSCs, which was indicative of inhibited NSC proliferation. Western blotting analysis revealed the protein levels of neuron-specific marker tubulin-βIII (TuJ1) and Mash1 were increased whilst the astrocyte-specific marker glial fibrillary acidic protein (GFAP) decreased. Immunofluorescence analysis showed OA significantly elevated the percentage of TuJ1-positive cells and reduced GFAP-positive cells. Using DNA microarray analysis, 183 genes were differentially regulated by OA. Through transcription factor binding site analyses of the upstream regulatory sequences of these genes, 87 genes were predicted to share a common motif for Nkx-2.5 binding. Finally, small interfering RNA (siRNA) methodology was used to silence Nkx-2.5 expression and found silence of Nkx-2.5 alone did not change the expression of TuJ-1 and the percentage of TuJ-1-positive cells. But in combination of OA treatment and silence of Nkx-2.5, most effects of OA on NSCs were abolished. These results indicated that OA is an effective inducer for NSCs differentiation into neurons at least partially by Nkx-2.5-dependent mechanism.

The molecular mechanisms underpinning the therapeutic properties of oleanolic acid, its isomer and derivatives for type 2 diabetes and associated complications

Recent research has uncovered the molecular mechanisms responsible for the therapeutic properties of oleanolic acid (OA), its isomer ursolic acid (UA), and derivatives. In particular, recent reports have highlighted the benefits of these compounds in the prevention and treatment of type 2 diabetes and associated life-threatening complications, such as nonalcoholic fatty liver disease, nephropathy, retinopathy, and atherosclerosis. The prevalence of type 2 diabetes is of major concern since it is reaching global epidemic levels. Treatments targeting the signaling pathways altered in type 2 diabetes are being actively investigated, and OA and UA in natural and derivative forms are potential candidates to modulate these pathways. We will explore the findings from in vitro and in vivo studies showing that these compounds: (i) improve insulin signaling and reduce hyperglycemia; (ii) reduce oxidative stress by upregulating anti-oxidants and; (iii) reduce inflammation by inhibiting proinflammatory signaling. We will discuss the molecular mechanisms underpinning these therapeutic properties in this review in order to provide a rationale for the future use of OA, UA, and their derivatives for the prevention and treatment of type 2 diabetes and associated comorbidities.

Blockage of progesterone receptor effectively protects pancreatic islet beta cell viability

The progesterone receptor (PR), a member of nuclear receptor superfamily, is closely associated with gestational, type 1 and type 2 diabetes. However, the underlying mechanisms remain obscure. Here we found that PR activation increased the pro-inflammatory cytokines (PIC)-induced injury in Min6 cells, and PR blockage with siRNA interference protected the cells from damage. Moreover, the new discovered PR antagonist SC51089 effectively improved cell survival by reducing the PIC-stimulated cell apoptosis in Min6 cells. Immunoblotting assays indicated that either PR agonist progesterone (P4) or PR-B over-expression promoted the PIC-induced reinforces of extracellular-signal-regulated kinase 1/2 phosphorylation (p-Erk) and protein 53 (p53), and the attenuations of protein kinase B phosphorylation (p-AKT) and tumor necrosis factor receptor-associated factor 2 (TRAF2). SC51089 could reverse all the P4- or PR-B over-expression induced effects. In addition, PR siRNA inference based assay further supported that SC51089 protected pancreatic islet beta cells from the PR activation or PIC-induced injury by targeting PR and this protective action was mediated by AKT signaling pathway. To our knowledge, this current work might be the first report on the regulation of PR in pancreatic islet beta cell survival. It is expected that SC51089, as a non-steroid PR antagonist, might also find its potential in anti-diabetic research.

Oleanolic acid suppresses resistin induction in adipocytes by modulating Tyk-STAT signaling

Oleanolic acid, a naturally occurring triterpenoid widely distributed in foods and medicinal plants, has anticancer, antioxidant, and antiaging properties. We hypothesized that oleanolic acid would suppress the production of the inflammatory adipokine resistin during adipogenic differentiation of 3T3-L1 adipocytes. 3T3-L1 adipocytes were cultured in adipogenic media with and without 1 to 25 μM oleanolic acid for up to 8 days to stimulate adipocyte differentiation. Adipocyte production of resistin was markedly enhanced during differentiation and was dose dependently attenuated by 1 to 25 μM oleanolic acid. This study further investigated whether Tyk2-Stat1/3 signaling was responsible for cellular production of resistin. Signal transducer and activator of transcription factor (STAT) 1 and STAT3 were activated during differentiation in a disparate temporal fashion; STAT1 was maximally phosphorylated on day 5 after initiating differentiation, whereas STAT3 was rapidly activated within 1 day of differentiation. When oleanolic acid was supplied to differentiating adipocytes, STAT1 and STAT3 phosphorylation was substantially suppressed. Upstream Tyk2 was rapidly activated in a manner similar to STAT3 and reactivated on days 3 to 5 after initiating differentiation, which was attenuated by incubating adipocytes with oleanolic acid. In addition, cellular expression of suppressor of cytokine signaling 3 (SOCS3), which inhibits Tyk2 activity, was markedly promoted from day 5 of adipocyte differentiation. Oleanolic acid attenuated SOCS3 expression, which was highly enhanced during the late phase of differentiation. Taken together, oleanolic acid suppressed adipocyte differentiation-associated resistin and adipogenesis production by disturbing the Tyk2-STAT1/3 signaling pathway and promoting SOCS3 expression. Therefore, oleanolic acid may be a possible bioactive agent that blunts adipogenesis and adipokine inflammation.

Antidiabetic effect of oleanolic acid: a promising use of a traditional pharmacological agent

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia. Although the clear mechanisms of DM and insulin resistance are still to be cleared, it has been well documented that reactive oxygen species (ROS) play a pivotal role in DM and multiple types of insulin resistance. For the past few years, natural substances have been shown to have the potential to treatment DM. Attention has been especially focused on plants rich in triterpenoids, which generally show antioxidant and antiglycation effect. In our previous studies, it was shown that oleanolic acid (OA), a natural triterpenoid and an aglycone of many saponins, is a potent antioxidant acting as not only a free radical-scavenger through direct chemical reactions but also as a biological molecule, which may enhance the antioxidant defenses. The present study aimed to investigate the potential antidiabetic effect of OA. Oleanolic acid showed a significant blood glucose-lowering and weight-losing effect in diabetic animals induced by streptozotocin (STZ). In the insulin resistant model, it was also shown that OA may promote insulin signal transduction and inhibit oxidative stress-induced hepatic insulin resistance and gluconeogenesis, in which process the phosphorylation of ERK and the protective effect on mitochondrial function may be involved. These findings may significantly better the understanding of the pharmacological actions of OA and advance therapeutic approaches to DM.

Biotransformation of oleanolic acid by Alternaria longipes and Penicillium adametzi

Microbial transformation of oleanolic acid (1) was carried out. Six transformed products (2-7) from 1 by Alternaria longipes and three transformed products (8-10) from 1 by Penicillium adametzi were isolated. Their structures were elucidated as 2α,3α,19α-trihydroxy-ursolic acid-28-O-β-d-glucopyranoside (2), 2α,3β,19α-trihydroxy-ursolic acid-28-O-β-d-glucopyranoside (3), oleanolic acid 28-O-β-d-glucopyranosyl ester (4), oleanolic acid-3-O-β-d-glucopyranoside (5), 3-O-(β-d-glucopyranosyl)-oleanolic acid-28-O-β-d-glucopyranoside (6), 2α,3β,19a-trihydroxy-oleanolic acid-28-O-β-d-glucopyranoside (7), 21β-hydroxyl oleanolic acid-28-O-β-d-glucopyranoside (8), 21β-hydroxyl oleanolic acid (9), and 7α,21β-dihydroxyl oleanolic acid (10) based on the extensive NMR studies. Among them, 10 was a new compound and compounds 5 and 8-10 had stronger cytotoxic activities against Hela cell lines than the substrate. At the same time, it was reported for the first time in this paper that the skeletons of compounds 2 and 3 were changed from oleanane to uranane and seven glycosidation products were obtained by biotransformation.

Synergistic antihyperglycemic effects between plant-derived oleanolic acid and insulin in streptozotocin-induced diabetic rats

Studies from our laboratories indicate that Syzygium cordatum leaf extract contains triterpene mixtures [oleanolic acid (OA) and ursolic acid (UA)] with hypoglycemic properties. The aims of this study were to investigate the hypoglycemic effects of Syzygium aromaticum-derived OA and whether OA influenced the blood glucose lowering effects of insulin in streptozotocin (STZ)-induced diabetic rats. We envisaged that OA may provide a strategy with different mechanism of action for effective diabetic therapy because no single-marketed antidiabetic drug is capable of achieving long-lasting blood glucose control. The effects of various doses of OA and/or standard antidiabetic drugs on blood glucose were monitored in nondiabetic and STZ-induced diabetic rats given a glucose load after an 18-h fast. Rats treated with deionized water and standard antidiabetic drugs acted as untreated and treated positive controls, respectively. Blood glucose concentrations were measured at 15-min intervals for the first hour and hourly thereafter for 3 h. Blood glucose concentrations were also monitored in animals treated with OA and/or standard antidiabetic drugs for 5 weeks. OA like insulin decreased blood glucose concentrations in nondiabetic and STZ-induced diabetic rats. Combined OA and insulin treatment had even greater antihyperglycemic response, suggestive of a synergistic effect of the two. After 5 weeks, STZ-induced diabetic rats exhibited hyperglycemia and depleted hepatic and muscle glycogen concentrations. OA treatment lowered the blood glucose with concomitant restoration of glycogen concentrations to near normalcy. Our results suggest that OA may have a role in improving insulin sensitivity. These findings merit further research in this field.

A novel screening model for the molecular drug for diabetes and obesity based on tyrosine phosphatase Shp2

Tyrosine phosphatase Src-homology phosphotyrosyl phosphatase 2 (Shp2) was identified as a potential molecular target for therapeutic treatment of diabetes and obesity. However, there is still no systematic research on the enhancers for the Shp2 enzyme. The present study established a novel powerful model for the high-throughput screening of Shp2 enhancers and successfully identified a new specific Shp2 enhancer, oleanolic acid, from Chinese herbs.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.