Flavone-based novel antidiabetic and antidyslipidemic agents

Synthesis of Mono- and Polyazole Hybrids Based on Polyfluoroflavones

The possibility of functionalization of 2-(polyfluorophenyl)-4H-chromen-4-ones, with them having different numbers of fluorine atoms, with 1,2,4-triazole or imidazole under conditions of base-promoted nucleophilic aromatic substitution has been shown. A high selectivity of mono-substitution was found with the use of an azole (1.5 equiv.)/NaOBu^t(1.5 equiv.)/MeCN system. The structural features of fluorinated mono(azolyl)-substituted flavones in crystals were established using XRD analysis. The ability of penta- and tetrafluoroflavones to form persubstituted products with triazole under azole (6 equiv.)/NaOBu^t(6 equiv.)/DMF conditions was found in contrast to similar transformations with imidazole. On the basis of mono(azolyl)-containing polyfluoroflavones in reactions with triazole and pyrazole, polynuclear hybrid compounds containing various azole fragments were obtained. For poly(pyrazolyl)-substituted flavones, green emission in the solid state under UV-irradiation was found, and for some derivatives, weak fungistatic activity was found.

Antidiabetic Activity of Mung Bean or Vigna radiata (L.) Wilczek Seeds in Alloxan-Induced Diabetic Mice

Introduction

Despite the development of oral hypoglycemic medications, diabetes and its associated complications continue to be significant clinical issues. The purpose of this study was to examine the antidiabetic effects of Vigna radiata (L.) Wilczek seeds in mice that had been given alloxan to cause diabetes.

Methods

In Swiss albino mice, diabetes was brought on by a single intraperitoneal injection of the drug alloxan (150 mg/kg). For 14 days, glibenclamide (5 mg/kg) and methanol extract of V. radiata seeds (100, 200, and 400 mg/kg) were given orally. Following oral administration of V. radiata to mice, the blood glucose levels (BGL) and body weight were measured at 7 and 14 days. The mice were sacrificed at the end of the trial, and blood samples were taken for the evaluation of insulin, glycated hemoglobin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), high-density lipoprotein (HDL), total cholesterol (TC), and triglyceride (TG) levels. It was determined how much glycogen was present in the liver. Additionally, the total phenolic and flavonoid contents of V. radiata were determined, along with the in vitro DPPH (2, 2 diphenyl-1-picrylhrazyl) free radical-scavenging activity. P < 0.05 was chosen as the cutoff for statistical significance.

Results

Following oral administration of V. radiata for 14 days, diabetic mice's BGL and bad cholesterol (TC and TG) levels significantly decreased, while HDL levels increased. Treatment with V. radiata significantly decreased the levels of AST, ALT, and glycated hemoglobin when compared with diabetes control. On the other hand, it raised insulin levels and the amount of liver glycogen. V. radiata underwent phytochemical analysis, which identified the presence of tannins, saponins, phenols, alkaloids, terpenoids, steroids, flavonoids, and glycosides. Per gram of V. radiata seed extract, the total phenolic content was 43.12 ± 3.14 mg of gallic acid equivalents, while the total flavonoid content was 38.35 ± 2.6 mg of quercetin equivalents. Ascorbic acid was shown to have an IC₅₀ value of 18.64 µg/ml during a DPPH-scavenging assay, while V. radiata had an IC₅₀ value of 73.35 µg/ml.

Conclusion

According to the findings of the current study, the methanolic extract of the seeds from the plant V. radiata possesses significant antidiabetic characteristics that are on par with those of the commonly used drug glibenclamide. Hence, V. radiata seems to be effective as a natural antidiabetic.

1, 2-trans-Stereoselective 7-O-Glycosylation of Flavonoids with Unprotected Pyranoses by Mitsunobu Reaction

The glycosylation of protecting-group-free pyranoses with flavonoids to generate flavonoid O-glycosides under Mitsunobu conditions was reported. The methodology allows to prepare a wide range of natural 7-flavonoid O -glycosides and their derivatives from commercially available chemicals in good to excellent yields with exclusive 1,2- trans -stereoselectivity regardless the anomeric configuration of employed pyranoses. The highly regioselective glycosylation was also achieved among different types of hydroxyl groups on the glycosyl acceptors.

Effect of Hydroxyl Groups Esterification with Fatty Acids on the Cytotoxicity and Antioxidant Activity of Flavones

Flavonoids and polyunsaturated fatty acids due to low cytotoxicity in vitro studies are suggested as potential substances in the prevention of diseases associated with oxidative stress. We examined novel 6-hydroxy-flavanone and 7-hydroxy-flavone conjugates with selected fatty acids (FA) of different length and saturation and examined their cytotoxic and antioxidant potential. Our findings indicate that the conjugation with FA affects the biological activity of both the original flavonoids. The conjugation of 6-hydroxy-flavanone increased its cytotoxicity towards prostate cancer PC3 cells. The most noticeable effect was found for oleate conjugate. A similar trend was observed for 7-hydroxy-flavone conjugates with the most evident effect for oleate and stearate. The cytotoxic potential of all tested conjugates was not specific towards PC3 because the viability of human keratinocytes HaCaT cells decreased after exposure to all conjugates. Additionally, we showed that esterification of the two flavonoids decreased their antioxidant activity compared to that of the original compounds. Of all the tested compounds, only 6-sorbic flavanone showed a slight increase in antioxidant potential compared to that of the original compound. Our data show that conjugated flavonoids are better absorbed and enhance cytotoxic effects, but the presence of FA lowered the antioxidant potential.

Methanolic Extract of Myrsine africana Leaf Ameliorates Hyperglycemia and Dyslipidemia in Alloxan-Induced Diabetic Albino Mice

Background. Diabetes mellitus is one of the leading public health problems globally, and its prevalence is increasing in Ethiopia. The current drugs for people with diabetes are costly, less effective, and less safe with a challenging administration method. Thus, globally, the need for alternative herbal antidiabetic medicines is increasing. In the previous studies, antioxidant activities have been seen in crude extracts of M. africana leaves, which is an auspicious sign of antidiabetic property. Accordingly, this study has evaluated the antidiabetic and antidyslipidemic activities of methanolic extract of M. africana leaves. Methods. Hypoglycemic and antihyperglycemic activities of the three doses (250 mg/kg, 500 mg/kg, and 1000 mg/kg) of crude methanolic extract of M. africana leaf were studied on normoglycemic, oral glucose-loaded, and alloxan-induced diabetic mice models. The effect of the extract on diabetic dyslipidemia, insulin and glycated hemoglobin levels, carbohydrate-metabolizing enzymes, and body weight was also studied in alloxan-induced diabetic mice. Glibenclamide (5 mg/kg) was used as a standard drug in all cases. Data analysis was carried out using mixed-design ANOVA. A $P$ value of ≤0.05 was considered a statistically significant difference. Results. The methanolic extract of M. africana leaf did not show acute toxicity up to the dose of 5000 mg/kg and showed better glucose utilization in the oral glucose tolerance test. After 14 days of treatment, M. africana leaf extract decreased the blood glucose level, glycated hemoglobin, glucose-6-phosphatase, and fructose-1-6-bisphosphatase in diabetic mice. In contrast, it increased hexokinase and insulin levels in diabetic mice. Moreover, weight loss and dyslipidemia profiles have been corrected significantly in diabetic mice. Conclusion. M. africana leaves showed antihyperglycemic and antidyslipidemic effects in alloxan-induced diabetic mice. That suggests M. africana may be a potential treatment option for diabetes in the future. However, further molecular studies are required to analyze the mechanisms.

Coronavirus Disease (COVID)-19 and Diabetic Kidney Disease

The present review describes COVID-19 severity in diabetes and diabetic kidney disease. We discuss the crucial effect of COVID-19-associated cytokine storm and linked injuries and associated severe mesenchymal activation in tubular epithelial cells, endothelial cells, and macrophages that influence neighboring cell homeostasis, resulting in severe proteinuria and organ fibrosis in diabetes. Altered microRNA expression disrupts cellular homeostasis and the renin-angiotensin-system, targets reno-protective signaling proteins, such as angiotensin-converting enzyme 2 (ACE2) and MAS1 receptor (MAS), and facilitates viral entry and replication in kidney cells. COVID-19-associated endotheliopathy that interacts with other cell types, such as neutrophils, platelets, and macrophages, is one factor that accelerates prethrombotic reactions and thrombus formation, resulting in organ failures in diabetes. Apart from targeting vital signaling through ACE2 and MAS, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are also associated with higher profibrotic dipeptidyl transferase-4 (DPP-4)-mediated mechanisms and suppression of AMP-activated protein kinase (AMPK) activation in kidney cells. Lowered DPP-4 levels and restoration of AMPK levels are organ-protective, suggesting a pathogenic role of DPP-4 and a protective role of AMPK in diabetic COVID-19 patients. In addition to standard care provided to COVID-19 patients, we urgently need novel drug therapies that support the stability and function of both organs and cell types in diabetes.

Interactions among Long Non-Coding RNAs and microRNAs Influence Disease Phenotype in Diabetes and Diabetic Kidney Disease

Large-scale RNA sequencing and genome-wide profiling data revealed the identification of a heterogeneous group of noncoding RNAs, known as long noncoding RNAs (lncRNAs). These lncRNAs play central roles in health and disease processes in diabetes and cancer. The critical association between aberrant expression of lncRNAs in diabetes and diabetic kidney disease have been reported. LncRNAs regulate diverse targets and can function as sponges for regulatory microRNAs, which influence disease phenotype in the kidneys. Importantly, lncRNAs and microRNAs may regulate bidirectional or crosstalk mechanisms, which need to be further investigated. These studies offer the novel possibility that lncRNAs may be used as potential therapeutic targets for diabetes and diabetic kidney diseases. Here, we discuss the functions and mechanisms of actions of lncRNAs, and their crosstalk interactions with microRNAs, which provide insight and promise as therapeutic targets, emphasizing their role in the pathogenesis of diabetes and diabetic kidney disease.

Loss of Mitochondrial Control Impacts Renal Health

Disruption of mitochondrial biosynthesis or dynamics, or loss of control over mitochondrial regulation leads to a significant alteration in fuel preference and metabolic shifts that potentially affect the health of kidney cells. Mitochondria regulate metabolic networks which affect multiple cellular processes. Indeed, mitochondria have established themselves as therapeutic targets in several diseases. The importance of mitochondria in regulating the pathogenesis of several diseases has been recognized, however, there is limited understanding of mitochondrial biology in the kidney. This review provides an overview of mitochondrial dysfunction in kidney diseases. We describe the importance of mitochondria and mitochondrial sirtuins in the regulation of renal metabolic shifts in diverse cells types, and review this loss of control leads to increased cell-to-cell transdifferentiation processes and myofibroblast-metabolic shifts, which affect the pathophysiology of several kidney diseases. In addition, we examine mitochondrial-targeted therapeutic agents that offer potential leads in combating kidney diseases.

Characterization of Alginate from Sargassum duplicatum and the Antioxidant Effect of Alginate–Okra Fruit Extracts Combination for Wound Healing on Diabetic Mice

Diabetes mellitus is a group of metabolic disorders characterized by high blood-glucose levels over a prolonged period that causes complications when an open wound is present. Alginate is an antioxidant and a good absorbent of exudates. Okra fruit contains flavonoids that can act as antioxidants. The antioxidant properties of extracts combination reduce blood-glucose levels significantly to accelerate the activities of wound-healing processes on diabetic mice. Alginate was characterized by Size Exclusion Chromatography-Multiple Angle Laser Light Scattering (SEC-MALLS), thermal stability and Proton Nuclear Magnetic Resonance (1H-NMR). The evaluation of wound healing on 36 male mice were divided into 12 groups including normal control (NC), diabetics control (DC), alginate (DA) and alginate–okra (DAO) groups in three different times by histopathology test on skin tissue. The results of SEC-MALLS analysis showed that alginate as single and homogeneous polysaccharide. The 1H-NMR spectrum showed that the mannuronate/guluronate ratio of the used alginate was 0.91. Alginate, okra fruit extract and their combination were classified as moderate and strong antioxidants. The numbers of fibrocytes, fibroblasts, collagen densities had significantly increased from three to seven days. In contrast, wound width, neutrophil, macrophages had significantly decreased at 14 days. The administration of extracts combination increased the re-epithelization of the wound area and wound-healing process on diabetic mice.

Cancer Biology and Prevention in Diabetes

The available evidence suggests a complex relationship between diabetes and cancer. Epidemiological data suggest a positive correlation, however, in certain types of cancer, a more complex picture emerges, such as in some site-specific cancers being specific to type I diabetes but not to type II diabetes. Reports share common and differential mechanisms which affect the relationship between diabetes and cancer. We discuss the use of antidiabetic drugs in a wide range of cancer therapy and cancer therapeutics in the development of hyperglycemia, especially antineoplastic drugs which often induce hyperglycemia by targeting insulin/IGF-1 signaling. Similarly, dipeptidyl peptidase 4 (DPP-4), a well-known target in type II diabetes mellitus, has differential effects on cancer types. Past studies suggest a protective role of DPP-4 inhibitors, but recent studies show that DPP-4 inhibition induces cancer metastasis. Moreover, molecular pathological mechanisms of cancer in diabetes are currently largely unclear. The cancer-causing mechanisms in diabetes have been shown to be complex, including excessive ROS-formation, destruction of essential biomolecules, chronic inflammation, and impaired healing phenomena, collectively leading to carcinogenesis in diabetic conditions. Diabetes-associated epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition (EndMT) contribute to cancer-associated fibroblast (CAF) formation in tumors, allowing the epithelium and endothelium to enable tumor cell extravasation. In this review, we discuss the risk of cancer associated with anti-diabetic therapies, including DPP-4 inhibitors and SGLT2 inhibitors, and the role of catechol-o-methyltransferase (COMT), AMPK, and cell-specific glucocorticoid receptors in cancer biology. We explore possible mechanistic links between diabetes and cancer biology and discuss new therapeutic approaches.

Discovery of Small-Molecule Modulators of Protein-RNA Interactions by Fluorescence Intensity-Based Binding Assay

Protein-RNA interactions mediate various cellular processes, the dysregulation of which has been associated with a list of diseases. Thus, novel experimental tools for monitoring protein-RNA interactions are highly desirable to identify new chemical modulators of these therapeutic targets. In this study, we constructed simple fluorescence intensity-based protein-RNA binding assays by testing multiple environment-sensitive organic fluorophores. We selected the oncogenic interaction between Lin28 and the let-7 microRNA and the important immunomodulatory Roquin-Tnf CDE interaction as representative targets. We adapted this assay to high-throughput screening for the identification of pyrazolyl thiazolidinedione-type molecules as potent small-molecule inhibitors of protein-microRNA interactions. We clearly showed the structure-activity relationships of this new class of Lin28-let-7 interaction inhibitors, and confirmed that cellular mature let-7 microRNAs and their target genes could be modulated upon treatment with the pyrazolyl thiazolidinedione-type inhibitor. We expect that our simple and adaptable screening approach can be applied for the development of various assay systems aimed at the identification of bioactive small molecules targeting protein-RNA interactions.

Evaluation of hypoglycemic, antihyperglycemic and antihyperlipidemic activities of 80% methanolic seed extract of Calpurnia aurea (Ait.) Benth. (Fabaceae) in mice

Background

Diabetes mellitus is one of the most common chronic health problems in the world. As currently available antidiabetic medications have limitations in terms of safety, efficacy, and cost, it is an important research area to investigate medicinal plants for new antidiabetic compounds that can lead to effective, safe and less costly pharmacotherapy. The present study was done to evaluate the antidiabetic and antidyslipidemic activities of 80% methanolic seed extract of Calpurnia aurea (Ait.) Benth. (Fabaceae) in mice.

Methods

Blood glucose lowering activity of three doses (2.75 mg/kg, 5.5 mg/kg and 11 mg/kg) of the hydromethanolic seed extract of Calpurnia aurea was studied in three animal models: normoglycemic mice, oral glucose-loaded mice, and streptozotocin-induced diabetic mice. Additionally, the effect of the seed extract on body weight and serum lipid profile was studied in the streptozotocin-induced diabetic mice. Glibenclamide (5 mg/kg) was used as a standard drug in all animal models of the study. Blood glucose level was measured using a glucose meter, whereas serum lipid level was measured using an automated chemistry analyzer. Data were analyzed using one-way analysis of variance followed by Tukey's post hoc multiple comparison test.

Results

Hydromethanolic extract of C. aurea seeds showed blood glucose lowering activity in all animal models, and it improved body weight loss and diabetic dyslipidemia in diabetic mice after 14 days of treatment.

Conclusion

This study revealed that hydromethanolic extract of Calpurnia aurea seeds has significant hypoglycemic, antihyperglycemic and antihyperlipidemic activities.

Natural product-based design, synthesis and biological evaluation of 2',3,4,4'-tetrahydrochalcone analogues as antivitiligo agents

A bioactive component, 2',3,4,4'-tetrahydrochalcone (RY3-a) was first isolated from Vernohia anthelmintica (L.) willd seeds, and a set of its analogs, RY3-a-1-RY3-a-15 and RY3-c were designed and synthesized. Biological activity assays showed that RY3-c exhibited better melanogenesis and antioxidant activity and lower toxicity in comparison with RY3-a and butin. Further study tests showed that RY3-c exhibited better melanogenesis activity compared with the positive control 8-methoxypsoralan (8-MOP) in a vitiligo mouse model, suggesting that RY3-c is a good candidate antivitiligo agent. Mechanistic studies showed that RY3-c could repair cell damage induced by excessive oxidative stress and may exert melanin synthesis activity in the mouse melanoma B16F10 cell line by activating the mitogen-activated protein kinase (MAPK) pathway and the upregulation of c-kit.

Antidiabetic Activities of Hydromethanolic Leaf Extract of Calpurnia aurea (Ait.) Benth. Subspecies aurea (Fabaceae) in Mice

Diabetes mellitus is one of the largest global health problems demanding preventive and new therapeutic interventions. Currently, there is a need for safe, effective, and less costly antidiabetic medications, and investigating medicinal plants for new antidiabetic medication is an interesting research area. Thus, the present study was done to evaluate the antidiabetic activities of 80% methanolic leaf extract of Calpurnia aurea (Ait.) Benth. subspecies aurea (Fabaceae) in mice. Hypoglycemic and antihyperglycemic activity of the three doses (100mg/kg, 200 mg/kg, and 400 mg/kg) of crude hydromethanolic leaf extract was studied on normoglycemic, oral glucose loaded, and streptozotocin-induced diabetic mice models. The effect of the extract on body weight and diabetic dyslipidemia was also studied on streptozotocin-induced diabetic mice. Glibenclamide (5 mg/kg) was used as a standard drug in all cases. A glucose meter and an automated chemistry analyzer were used to measure blood glucose and serum lipid level respectively. Data were analyzed using one-way analysis of variance followed by Tukey's post hoc multiple comparison test. All the three doses of the plant extract (100mg/kg, 200 mg/kg, and 400 mg/kg) showed a significant (p<0.05) antihyperglycemic activity in the diabetic mice at the 7th and 14th day of repeated daily dose administration as compared to the negative diabetic control. But, the extract did not show significant blood glucose lowering activity in normoglycemic, oral glucose loaded, and diabetic mice after single dose administration, and it did not significantly improve the body weight loss and diabetic dyslipidemia of diabetic mice after repeated daily dose administration for 14 days. This study revealed that the hydromethanolic extract of Calpurnia aurea leaves possesses significant antihyperglycemic activity justifying the traditional use of the plant for diabetes.

Bioactive flavonoids in medicinal plants: Structure, activity and biological fate

Flavonoids, a class of polyphenol secondary metabolites, are presented broadly in plants and diets. They are believed to have various bioactive effects including anti-viral, anti-inflammatory, cardioprotective, anti-diabetic, anti-cancer, anti-aging, etc. Their basic structures consist of C₆-C₃-C₆ rings with different substitution patterns to produce a series of subclass compounds, and correlations between chemical structures and bioactivities have been studied before. Given their poor bioavailability, however, information about associations between structure and biological fate is limited and urgently needed. This review therefore attempts to bring some order into relationships between structure, activity as well as pharmacokinetics of bioactive flavonoids.

Assay method for quality control and stability studies of a new anti-diabetic and anti-dyslipidemic flavone (S002-853)

BACKGROUND

Flavonoid-rich extract of the plant is long known for its anti-diabetic activities in traditional medicine. S002-853, a new flavone derivative synthesized by Central Drug Research Institute (CDRI) has been used for the present study.

OBJECTIVES

The present study aimed at development of an assay method for quality control (QC) and stability studies of a new anti-diabetic and anti-dyslipidemic agent CDRI compound S002-853.

MATERIALS AND METHODS

A validated high-performance liquid chromatography analysis method for S002-853 was developed for in process QC and stability studies. The separation was achieved on a RP-C18 (25 cm × 0.4 cm, 5 μm, Phenomenex) at 240 nm with flow rate of 1.0 ml/min. This method was applied successfully in establishing forced degradation and drug-excipient testing protocols as per International Conference on Harmonization guidelines.

RESULTS

The result of estimation and stress testing studies indicated a high degree of selectivity of this method. S002-853 was most stable at pH 7 and under photolytic conditions. The temperature degradation pattern of S002-853 was found to follow the zero order degradation.

CONCLUSION

The method described is easy and simple hence can be easily reproduced. This method can be very useful for bulk manufacture QC, and drug development process.

One-Pot Synthesis of N-Substituted β-Amino Alcohols from Aldehydes and Isocyanides

A practical two-stage one-pot synthesis of N-substituted β-amino alcohols using aldehydes and isocyanides as starting materials has been developed. This method features mild reaction conditions, broad scope, and general tolerance of functional groups. Based on a less common central carbon-carbon bond disconnection, this protocol complements traditional approaches that involve amines and various carbon electrophiles (epoxides, α-halo ketones, β-halohydrins). Medicinally relevant products can be prepared in a concise and efficient way from simple building blocks, as demonstrated in the synthesis of the antiasthma drug salbutamol. Upgrading the synthesis to an enantioselective variant is also feasible.

Functionalised Mn(VI)-nanoparticles: an advanced high-valent magnetic catalyst

We discover Mn(VI)-nanoparticles (NPs) bearing functional groups, high oxidation state, strong electron affinity, unique redox and paramagnetic nature, which opens up a new avenue to catalysis, magnetism and material application. However, its synthesis is challenging and remains unexplored because of associated serious difficulties. A simple benign synthetic strategy is devised to fabricate the high-valent NPs using mild reducing agent bromide, which transformed Mn(VII) to valuable Mn(VI)-species. The EELS-imaging of individual elements, ESI-MS, XPS and other techniques established its composition as Br(Me3SiO)Mn(VI)O2. It revealed significantly improved magnetic moment (SQUID) with isotropic hyperfine splitting of six line spectrum (EPR). The high-oxidation state and incorporated-ligands of the metals present on the active surface of the NPs led to development of a general catalytic process for oxidative heterodifunctionalisation to C-C triple bond towards formation of a new O-C/N-C/S-C and C-C coupling cum cyclisation to biologically important flavones and their aza- and marcapto-analogues, and valuable enaloxy synthons.

Flavones: an important scaffold for medicinal chemistry

Flavones have antioxidant, anti-proliferative, anti-tumor, anti-microbial, estrogenic, acetyl cholinesterase, anti-inflammatory activities and are also used in cancer, cardiovascular disease, neurodegenerative disorders, etc. Also, flavonoids are found to have an effect on several mammalian enzymes like protein kinases that regulate multiple cell signaling pathways and alterations in multiple cellular signaling pathways are frequently found in many diseases. Flavones have been an indispensable anchor for the development of new therapeutic agents. The majority of metabolic diseases are speculated to originate from oxidative stress, and it is therefore significant that recent studies have shown the positive effect of flavones on diseases related to oxidative stress. Due to the wide range of biological activities of flavones, their structure-activity relationships have generated interest among medicinal chemists. The outstanding development of flavones derivatives in diverse diseases in very short span of time proves its magnitude for medicinal chemistry research. The present review gives detail about the structural requirement of flavone derivatives for various pharmacological activities. This information may provide an opportunity to scientists of medicinal chemistry discipline to design selective, optimize as well as poly-functional flavone derivatives for the treatment of multi-factorial diseases.

Extract of okra lowers blood glucose and serum lipids in high-fat diet-induced obese C57BL/6 mice

Okra is an important tropical vegetable and source of dietary medicine. Here, we assayed the effects of an ethanol extract of okra (EO) and its major flavonoids isoquercitrin and quercetin 3-O-gentiobioside on metabolic disorders in high-fat diet-induced obese mouse. We found that treatment with EO, isoquercitrin and quercetin 3-O-gentiobioside reduced blood glucose and serum insulin levels and improved glucose tolerance in obese mice. Meanwhile, serum triglyceride levels and liver morphology in the mice were significantly ameliorated by EO and isoquercitrin treatment. Total cholesterol levels in isoquercitrin and quercetin 3-O-gentiobioside treated mice were also reduced. We also found that EO inhibited the expression of nuclear receptor transcription factor PPARγ, which is an important regulator of lipid and glucose homeostasis. Furthermore, we determined that EO and quercetin 3-O-gentiobioside have antioxidant activity in vitro. Our results indicate that okra may serve as a dietary therapy for hyperglycemia and hypertriglyceridemia.

Animal models of diabetes mellitus for islet transplantation

Due to current improvements in techniques for islet isolation and transplantation and protocols for immunosuppressants, islet transplantation has become an effective treatment for severe diabetes patients. Many diabetic animal models have contributed to such improvements. In this paper, we focus on 3 types of models with different mechanisms for inducing diabetes mellitus (DM): models induced by drugs including streptozotocin (STZ), pancreatomized models, and spontaneous models due to autoimmunity. STZ-induced diabetes is one of the most commonly used experimental diabetic models and is employed using many specimens including rodents, pigs or monkeys. The management of STZ models is well established for islet studies. Pancreatomized models reveal different aspects compared to STZ-induced models in terms of loss of function in the increase and decrease of blood glucose and therefore are useful for evaluating the condition in total pancreatomized patients. Spontaneous models are useful for preclinical studies including the assessment of immunosuppressants because such models involve the same mechanisms as type 1 DM in the clinical setting. In conclusion, islet researchers should select suitable diabetic animal models according to the aim of the study.