Antihyperglycemic Effect of Umbelliferone in Streptozotocin-Diabetic Rats

Novel thiazolidin-4-one benzenesulfonamide hybrids as PPARγ agonists: Design, synthesis and in vivo anti-diabetic evaluation

In the current study, two series of novel thiazolidin-4-one benzenesulfonamide arylidene hybrids 9a-l and 10a-f were designed, synthesized and tested in vitro for their PPARɣ agonistic activity. The phenethyl thiazolidin-4-one sulphonamide 9l showed the highest PPARɣ activation % by 41.7%. Whereas, the 3-methoxy- and 4-methyl-4-benzyloxy thiazolidin-4-one sulphonamides 9i, and 9k revealed moderate PPARɣ activation % of 31.7, and 32.8%, respectively, in addition, the 3-methoxy-3-benzyloxy thiazolidin-4-one sulphonamide 10d showed PPARɣ activation % of 33.7% compared to pioglitazone. Compounds 9b, 9i, 9k, 9l, and 10d revealed higher selectivity to PPARɣ over the PPARδ, and PPARα isoforms. An immunohistochemical study was performed in HepG-2 cells to confirm the PPARɣ protein expression for the most active compounds. Compounds 9i, 9k, and 10d showed higher PPARɣ expression than that of pioglitazone. Pharmacological studies were also performed to determine the anti-diabetic activity in rats at a dose of 36 mg/kg, and it was revealed that compounds 9i and 10d improved insulin secretion as well as anti-diabetic effects. The 3-methoxy-4-benzyloxy thiazolidin-4-one sulphonamide 9i showed a better anti-diabetic activity than pioglitazone. Moreover, it showed a rise in blood insulin by 4-folds and C-peptide levels by 48.8%, as well as improved insulin sensitivity. Moreover, compound 9i improved diabetic complications as evidenced by decreasing liver serum enzymes, restoration of total protein and kidney functions. Besides, it combated oxidative stress status and exerted anti-hyperlipidemic effect. Compound 9i showed a superior activity by normalizing some parameters and amelioration of pancreatic, hepatic, and renal histopathological alterations caused by STZ-induction of diabetes. Molecular docking studies, molecular dynamic simulations, and protein ligand interaction analysis were also performed for the newly synthesized compounds to investigate their predicted binding pattern and energies in PPARɣ binding site.

Dietary Polyphenols: Review on Chemistry/Sources, Bioavailability/Metabolism, Antioxidant Effects, and Their Role in Disease Management

Polyphenols, as secondary metabolites ubiquitous in plant sources, have emerged as pivotal bioactive compounds with far-reaching implications for human health. Plant polyphenols exhibit direct or indirect associations with biomolecules capable of modulating diverse physiological pathways. Due to their inherent abundance and structural diversity, polyphenols have garnered substantial attention from both the scientific and clinical communities. The review begins by providing an in-depth analysis of the chemical intricacies of polyphenols, shedding light on their structural diversity and the implications of such diversity on their biological activities. Subsequently, an exploration of the dietary origins of polyphenols elucidates the natural plant-based sources that contribute to their global availability. The discussion extends to the bioavailability and metabolism of polyphenols within the human body, unraveling the complex journey from ingestion to systemic effects. A central focus of the review is dedicated to unravelling the antioxidant effects of polyphenols, highlighting their role in combating oxidative stress and associated health conditions. The comprehensive analysis encompasses their impact on diverse health concerns such as hypertension, allergies, aging, and chronic diseases like heart stroke and diabetes. Insights into the global beneficial effects of polyphenols further underscore their potential as preventive and therapeutic agents. This review article critically examines the multifaceted aspects of dietary polyphenols, encompassing their chemistry, dietary origins, bioavailability/metabolism dynamics, and profound antioxidant effects. The synthesis of information presented herein aims to provide a valuable resource for researchers, clinicians, and health enthusiasts, fostering a deeper understanding of the intricate relationship between polyphenols and human health.

Umbelliferon: a review of its pharmacology, toxicity and pharmacokinetics

Coumarin, a plant secondary metabolite, has various pharmacological activities, including antioxidant stress and anti-inflammatory effects. Umbelliferone, a common coumarin compound found in almost all higher plants, has been extensively studied for its pharmacological effects in different disease models and doses with complex action mechanisms. This review aims to summarize these studies and provide useful information to relevant scholars. The pharmacological studies demonstrate that umbelliferone has diverse effects such as anti-diabetes, anti-cancer, anti-infection, anti-rheumatoid arthritis, neuroprotection, and improvement of liver, kidney, and myocardial tissue damage. The action mechanisms of umbelliferone include inhibition of oxidative stress, inflammation, and apoptosis, improvement of insulin resistance, myocardial hypertrophy, and tissue fibrosis, in addition to regulation of blood glucose and lipid metabolism. Among the action mechanisms, the inhibition of oxidative stress and inflammation is the most critical. In short, these pharmacological studies disclose that umbelliferone is expected to treat many diseases, and more research should be conducted.

Umbelliferone loaded PEGylated liposomes: preparation, characterization and its mitigatory effects on Dalton's ascites lymphoma development

Umbelliferone (UB) is a phenylpropanoid-based pharmacologically active agent with promising anti-tumor activities. However, complete elucidation of its therapeutic efficacy remains challenging due to low solubility and bioavailability. The present study aimed to develop a liposomal delivery system for UB to enhance its therapeutic efficacy against Dalton's ascites lymphoma tumor model. Umbelliferone-encapsulated nanoliposomes (nLUB) were prepared using the thin-film hydration method and performed a series of characterizations to confirm successful development. The nLUB showed a particle size of 116 ± 3.2 nm with a negative surface charge and encapsulation efficiency of 78%. In vitro study results showed that nLUB treatment significantly enhanced cellular uptake and apoptosis induction in lymphoma cells compared to free UB. nLUB treatment significantly stabilized body weight, reduced tumor growth, and improved the serum biochemical and hematological parameters of experimental animals, thereby improving their overall survivability compared to an free UB. Our result indicates that nanoencapsulation enhanced the therapeutic potential of UB, which may find its way to clinical application in the near future.

Anti-diabetic Effects of Two Species of Eryngium on Streptozotocin-induced Diabetic Mice

Background: Eryngium is a genus with 274 species, which belongs to the Umbelliferae family. The nine species of this genus are endemic to Iran. The existence of terpenoids, saponins, flavonoids, and steroid components in most Eryngium species is the reason behind their anti-inflammatory, anti-cancer, and, especially, anti-diabetic effects among the well-known medicinal plants. Objectives: This study aimed to evaluate the effects of anti-diabetic features of Eryngium thyrsoideum and caucasicum on streptozotocin (STZ)-induced diabetic mice. Methods: The extract of the plants’ dried samples was prepared by using 70% ethanol solvent and adopting the maceration method. The mice were divided into eight groups, and the mice with a high blood glucose of more than 200 mg/dL were assigned to diabetic groups. Diabetic animals received different doses of the extract orally or through intraperitoneal (IP) injection for eighteen days. The animals were anesthetized by IP injection of ketamine and xylazine, and serum samples were isolated. Results: The results showed that hydroalcoholic extract of E. thyrsoideum significantly reduced the blood sugar level in diabetic groups receiving the extract (oral and IP) in low (100 mg/kg) and high (300 mg/kg) doses. Overall, oral glucose tolerance decreased significantly after two hours. Coincidental management of STZ and 300 mg/kg of the extract consumed orally reduced the blood sugar level remarkably. Serum malondialdehyde (MDA) and serum insulin levels significantly decreased and increased, respectively, in the diabetic groups receiving low and high doses (oral and IP) of the E. thyrsoideum extract. Conclusions: In sum, receiving 100 mg/kg and 300 mg/kg of hydroalcoholic extract (oral and IP) decreased the blood sugar level, while receiving oral glucose tolerance, serum MDA, and serum insulin caused a significant increase.

Umbelliferone attenuates diabetic cardiomyopathy by suppression of JAK/STAT signaling pathway through amelioration of oxidative stress and inflammation in rats

Umbelliferone (UMB), 7-hydroxycoumarin, is a naturally occurring coumarin derivative that has a plethora of biological and therapeutic activities. The focus of this research was to elucidate the curative effects of two different doses of UMB on diabetic cardiomyopathy (DCM) in a type 2 diabetic rat model induced by 50 mg/kg body weight of streptozotocin (STZ). Diabetic rats orally received 10 or 30 mg/kg of UMB daily for 8 weeks. Compared to the nontreated diabetic group, both UMB treatment doses significantly decreased glucose levels, glycated hemoglobin (HbA1c), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), creatine kinase MB (CK-MB), cardiovascular risk indices, and oxidative stress by reducing malondialdehyde (MDA) and increasing the activity of the antioxidant enzymes. The hypercholesterolemia and hypertriglyceridemia also dramatically decreased in diabetic groups with UMB treatments accompanied by an improvement in insulin, and insulin sensitivity indices (HOMA-IR and QUICKI). Furthermore, the cardiac gene expressions and protein levels of Janus kinase2 (JAK2), signal transducer and activator of transcription3 (STAT3), and transforming growth factor beta1 (TGF-β1) were also markedly downregulated in a dose-dependent manner by UMB treatments. Finally, the biochemical results were assured by the reduction of histological alterations in cardiac tissues. In conclusion, UMB is a propitious substance for the treatment of DCM by virtuousness of its antihyperglycemic, antihyperlipidemic, antioxidant, and anti-inflammatory properties through modulating the JAK/STAT signaling pathway that may be the underlying mechanism in UMB action.

Systematic assessment of streptozotocin-induced diabetic metabolic alterations in rats using metabolomics

PURPOSE

Type 1 diabetes is characterized by elevated blood glucose levels, which negatively impacts multiple organs and tissues throughout the body, and its prevalence is on the rise. Prior reports primarily investigated the serum and urine specimen from diabetic patients. However, only a few studies examined the overall metabolic profile of diabetic animals or patients. The current systemic investigation will benefit the knowledge of STZ-based type 1 diabetes pathogenesis.

METHODS

Male SD rats were arbitrarily separated into control and streptozotocin (STZ)-treated diabetic rats (n = 7). The experimental rats received 50mg/kg STZ intraperitoneal injection daily for 2 consecutive days. Following 6 weeks, metabolites were assessed via gas chromatography-mass spectrometry (GC-MS), and multivariate analysis was employed to screen for differentially expressed (DE) metabolites between the induced diabetic and normal rats.

RESULTS

We identified 18, 30, 6, 24, 34, 27, 27 and 12 DE metabolites in the serum, heart, liver, kidney, cortex, renal lipid, hippocampus, and brown fat tissues of STZ-treated diabetic rats, compared to control rats. Based on our analysis, the largest differences were observed in the amino acids (AAs), B-group vitamin, and purine profiles. Using the metabolic pathway analysis, we screened 13 metabolic pathways related to the STZ-exposed diabetes pathogenesis. These pathways were primarily AA metabolism, followed by organic acids, sugars, and lipid metabolism.

CONCLUSION

Based on our GC-MS analysis, we identified potential metabolic alterations within the STZ-exposed diabetic rats, which may aid in the understanding of diabetes pathogenesis.

Investigation of the Chemical Composition, Antihyperglycemic and Antilipidemic Effects of Bassia eriophora and Its Derived Constituent, Umbelliferone on High-Fat Diet and Streptozotocin-Induced Diabetic Rats

This study was designed to investigate the chemical profile, antihyperglycemic and antilipidemic effect of total methanolic extract (TME) of Bassia eriophora and isolated pure compound umbelliferone (UFN) in high-fat diet (HFD)- and streptozotocin (STZ)- induced diabetic rats. TME was subjected to various techniques of chromatography to yield UFN. Diabetes was induced after eight weeks of HFD by administration of STZ (40 mg/kg) intraperitoneally, and experimental subjects were divided into five groups. The diabetic control showed an increase in levels of blood glucose throughout the experiment. Treatments were initiated in the other four groups with glibenclamide (GLB) (6 mg/kg), TME (200 mg/kg and 400 mg/kg) and isolated UFN (50 mg/kg) orally. The effect on blood glucose, lipid profile and histology of the pancreatic and adipose tissues was assessed. Both 200 and 400 mg/kg of TME produced a comparably significant decrease in blood glucose levels and an increase in insulin levels with GLB. UFN began to show a better blood sugar-lowering effect after 14 days of treatment, comparatively. However, both 400 mg/kg TME and UFN significantly returned blood glucose levels in diabetic rats compared to normal rats. Analysis of the lipid profile showed that while HFD + STZ increased all lipid profile parameters, TME administration produced a significant decrease in their levels. Histopathological examinations showed that treatment with TME and UFN revealed an improved cellular architecture, with the healthy islets of Langerhans and compact glandular cells for pancreatic cells distinct from damaged cells in non-treated groups. Conversely, the adipose tissue displayed apparently normal polygonal fat cells. Therefore, these results suggest that TME has the potential to ameliorate hyperglycemia conditions and control lipid profiles in HFD + STZ-induced diabetic rats.

Umbelliferone ameliorates ulcerative colitis induced by acetic acid via modulation of TLR4/NF-κB-p65/iNOS and SIRT1/PPARγ signaling pathways in rats

Ulcerative colitis (UC) is a common chronic, idiopathic inflammatory bowel disease associated with inflammatory perturbation and oxidative stress. Umbelliferone (UMB) is a potent anti-inflammatory and antioxidant coumarin derivative. Depending on the possible mechanisms, we aimed to explore and elucidate the therapeutic potential of UMB on UC-inflammatory response and oxidative injury-induced via intrarectal administration of acetic acid (AA) in rats. Animals were assigned into four groups: control group, UMB (30 mg/kg, oral)-treated group, AA-induced colitis model group (2 ml of AA; 3% v/v), and colitis treated with UMB group. The results showed that UMB improved macroscopic and histological tissue injury caused by the AA. Mechanistically, UMB reduced the elevated colonic TNF-α, IL-6, MPO, and VCAM-1 and downregulated the gene and protein expression of TLR4, NF-κB, and iNOS signaling factors, exhibiting potent anti-inflammatory effects. Moreover, UMB upregulated the gene and protein expression of both SIRT1 and PPARγ signaling pathways, thereby inhibiting both oxidative injury and inflammatory response. Conclusively, UMB protected rats against AA-induced UC by suppressing the TLR4/NF-κB-p65/iNOS signaling pathway and promoting the SIRT1/PPARγ signaling. Our results showed the effectiveness of UMB in alleviating the pathogenesis of UC and introduced it as a possible therapeutic applicant for clinical application.

Antidiabetic and antihyperlipidemic effects of Premna spinosa bark in experimental animal models

The purpose of the study is to evaluate the antidiabetic and hyperlipidemic potential of stem bark extract of Premna spinosa (Lamiaceae), by using streptozotocin (STZ)-nicotinamide (NA)-induced diabetic and triton-induced hyperlipidemic models in albino rats. The blood glucose, total cholesterol, and triglyceride levels were determined in STZ-NA-induced diabetic and triton-induced hyperlipidemic rats, as per the respective protocols. It was found that there is the dose dependent and significant reduction in foregoing parameters on the administration of extract from Premna spinosa stem bark at the doses of 200, 400, and 800 mg/kg body weight to diabetic and hyperlipidemic rats. From these observed results it may be inferred that the stem bark of Premna spinosa possesses remarkable antidiabetic and antihyperlipidemic properties.

A Review of Coumarins and Coumarin-Related Compounds for Their Potential Antidiabetic Effect

Background and aims:

Worldwide, type 2 diabetes mellitus accounts for a considerable burden of disease, with an estimated global cost of >800 billion USD annually. For this reason, the search for more effective and efficient therapeutic anti-diabetic agents is continuing. Coumarins are naturally derived and synthetic molecules with a wide variety of biological actions. The most common application of these molecules in medicine is for their thrombostatic activity. This study aims to give an overview of the current knowledge about the applicability of these chemical products in the therapeutic strategy against diabetes and its complications.

Methods:

For this purpose, we searched internet databases for publications and abstracts in English that investigated the effects of coumarins or coumarin-like agents with potential anti-diabetic activity.

Results:

The result is that a variety of these agents have proven in in vitro, in silico, and simple animal models to possess properties that may reduce the glucose absorption rate in the intestines, increase the level of insulin, increase the cellular uptake of glucose or reduce the gluconeogenesis. In addition, some of these agents also reduced the level of glycation of peptides in diabetic animal models and showed antioxidant properties.

Conclusion:

In conclusion, we can summarize that coumarins and their related derivatives may be potential antidiabetic agents. Useful formulations with appropriate pharmacokinetic and pharmacodynamic properties must be developed and tested for their efficacy and toxicity in comprehensive animal models before they can enter clinical trials.

Antioxidant Potential of Adiponectin and Full PPAR-γ Agonist in Correcting Streptozotocin-Induced Vascular Abnormality in Spontaneously Hypertensive Rats

Oxidative stress, which is associated with metabolic and anthropometric perturbations, leads to reactive oxygen species production and decrease in plasma adiponectin concentration. We investigated pharmacodynamically the pathophysiological role and potential implication of exogenously administered adiponectin with full and partial peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonists on modulation of oxidative stress, metabolic dysregulation, and antioxidant potential in streptozotocin-induced spontaneously hypertensive rats (SHR). Group I (WKY) serves as the normotensive control, whereas 42 male SHRs were randomized equally into 7 groups (n = 6); group II serves as the SHR control, group III serves as the SHR diabetic control, and groups IV, V, and VI are treated with irbesartan (30 mg/kg), pioglitazone (10 mg/kg), and adiponectin (2.5 μg/kg), whereas groups VII and VIII received cotreatments as irbesartan+adiponectin and pioglitazone+adiponectin, respectively. Diabetes was induced using an intraperitoneal injection of streptozotocin (40 mg/kg). Plasma adiponectin, lipid contents, and arterial stiffness with oxidative stress biomarkers were measured using an in vitro and in vivo analysis. Diabetic SHRs exhibited hyperglycemia, hypertriglyceridemia, hypercholesterolemia, and increased arterial stiffness with reduced plasma adiponectin and antioxidant enzymatic levels (P < 0.05). Diabetic SHRs pretreated with pioglitazone and adiponectin separately exerted improvements in antioxidant enzyme activities, abrogated arterial stiffness, and offset the increased production of reactive oxygen species and dyslipidemic effects of STZ, whereas the blood pressure values were significantly reduced in the irbesartan-treated groups (all P < 0.05). The combined treatment of exogenously administered adiponectin with full PPAR-γ agonist augmented the improvement in lipid contents and adiponectin concentration and restored arterial stiffness with antioxidant potential effects, indicating the degree of synergism between adiponectin and full PPAR-γ agonists (pioglitazone).

Umbelliferone ameliorates oxidative stress and testicular injury, improves steroidogenesis and upregulates peroxisome proliferator-activated receptor gamma in type 2 diabetic rats

OBJECTIVES

Diabetes mellitus (DM) is a chronic disease associated with serious complications, including male infertility. Umbelliferone (UMB) is a coumarin with promising antioxidant, anti-inflammatory and other beneficial effects. This study investigated the ameliorative effect of UMB against testicular injury, oxidative stress and altered steroidogenesis in rats with type 2 DM.

METHODS

Rats received a high fat diet for 4 weeks followed by a single injection of streptozotocin. Diabetic rats were treated with UMB or pioglitazone (PIO) for 6 weeks and samples were collected for analysis.

KEY FINDINGS

Diabetic rats exhibited hyperglycemia, insulin resistance and dyslipidemia associated with increased serum pro-inflammatory cytokines, and decreased gonadotropins and testosterone. UMB significantly ameliorated metabolic alterations, decreased pro-inflammatory cytokines, and increased gonadotropins and testosterone levels. UMB prevented testicular injury, suppressed lipid peroxidation and nitric oxide and increased antioxidants in diabetic rats. In addition, UMB upregulated testicular gonadotropins receptors, steroidogenesis markers (steroidogenic acute regulatory protein, cytochrome P450 family 17 subfamily A member 1 [CYP17A1], 3β-hydroxysteroid dehydrogenase [3ß-HSD] and 17ß-hydroxysteroid dehydrogenase [17ß-HSD]), and peroxisome proliferator-activated receptor gamma (PPARγ) expression.

CONCLUSIONS

UMB prevents testicular injury by preventing metabolic alterations, suppressing oxidative damage and inflammation, and boosting antioxidant defenses in diabetic rats. UMB enhanced pituitary-gonadal axis and steroidogenesis and upregulated testicular PPARγ in diabetic rats. Thus, UMB may represent a protective agent against testicular injury and sexual dysfunction associated with chronic hyperglycemia.

Computer-Aided Drug Design Applied to Secondary Metabolites as Anticancer Agents

Computer-Aided Drug Design (CADD) techniques have garnered a great deal of attention in academia and industry because of their great versatility, low costs, possibilities of cost reduction in in vitro screening and in the development of synthetic steps; these techniques are compared with highthroughput screening, in particular for candidate drugs. The secondary metabolism of plants and other organisms provide substantial amounts of new chemical structures, many of which have numerous biological and pharmacological properties for virtually every existing disease, including cancer. In oncology, compounds such as vimblastine, vincristine, taxol, podophyllotoxin, captothecin and cytarabine are examples of how important natural products enhance the cancer-fighting therapeutic arsenal. In this context, this review presents an update of Ligand-Based Drug Design and Structure-Based Drug Design techniques applied to flavonoids, alkaloids and coumarins in the search of new compounds or fragments that can be used in oncology. A systematical search using various databases was performed. The search was limited to articles published in the last 10 years. The great diversity of chemical structures (coumarin, flavonoids and alkaloids) with cancer properties, associated with infinite synthetic possibilities for obtaining analogous compounds, creates a huge chemical environment with potential to be explored, and creates a major difficulty, for screening studies to select compounds with more promising activity for a selected target. CADD techniques appear to be the least expensive and most efficient alternatives to perform virtual screening studies, aiming to selected compounds with better activity profiles and better "drugability".

Ameliorative effects of endurance training and Matricaria chamomilla flowers hydroethanolic extract on cognitive deficit in type 2 diabetes rats

Diabetes mellitus is mainly associated with degeneration of the central nervous system, which eventually leads to cognitive deficit. Although some studies suggest that exercise can improve the cognitive decline associated with diabetes, the potential effects of endurance training (ET) accompanied by Matricaria chamomilla (M.ch) flowers extract on cognitive impairment in type 2 diabetes has been poorly understood. Forty male Wistar rats were randomized into 5 equal groups of 8: healthy-sedentary (H-sed), diabetes-sedentary (D-sed), diabetes-endurance training (D-ET), diabetes-Matricaria chamomilla. (D-M.ch), and diabetes-endurance training-Matricaria chamomilla. (D-ET-M.ch). Nicotinamide (110 mg/kg, i.p.) and Streptozotocin (65 mg/kg, i.p.) were utilized to initiate type 2 diabetes. Then, ET (5 days/week) and M.ch (200 mg/kg body weight/daily) were administered for 12 weeks. After 12 weeks of the experiment, cognitive functions were assessed using the Morris Water Maze (MWM) test and a passive avoidance paradigm using a shuttle box device. Subsequently, using crystal violet staining, neuron necrosis was examined in the CA3 area of the hippocampus. Diabetic rats showed cognitive impairment following an increase in the number of necrotic cells in region CA3 of the hippocampal tissue. Also, diabetes increased serum levels of lipid peroxidation and decreased total antioxidant capacity in serum and hippocampal tissue. ET + M.ch treatment prevented the necrosis of neurons in the hippocampal tissue. Following positive changes in hippocampal tissue and serum antioxidant enzyme levels, an improvement was observed in the cognitive impairment of the diabetic rats receiving ET + M.ch. Therefore the results showed that treatment with ET + M.ch could ameliorate memory and inactive avoidance in diabetic rats. Hence, the use of ET + M.ch interventions is proposed as a new therapeutic perspective on the death of hippocampal neurons and cognitive deficit caused by diabetes.

Renoprotective and haemodynamic effects of adiponectin and peroxisome proliferator-activated receptor agonist, pioglitazone, in renal vasculature of diabetic Spontaneously hypertensive rats

Pioglitazone, a therapeutic drug for diabetes, possesses full PPAR-γ agonist activity and increase circulating adiponectin plasma concentration. Plasma adiponectin concentration decreases in hypertensive patients with renal dysfunctions. Present study investigated the reno-protective, altered excretory functions and renal haemodynamic responses to adrenergic agonists and ANG II following separate and combined therapy with pioglitazone in diabetic model of hypertensive rats. Pioglitazone was given orally [10mg/kg/day] for 28 days and adiponectin intraperitoneally [2.5μg/kg/day] for last 7 days. Groups of SHR received either pioglitazone or adiponectin in combination. A group of Wistar Kyoto rats [WKY] served as normotensive controls, whereas streptozotocin administered SHRs served as diabetic hypertensive rats. Metabolic data and plasma samples were taken on day 0, 8, 21 and 28. In acute studies, the renal vasoconstrictor actions of Angiotensin II [ANGII], noradrenaline [NA], phenylephrine [PE] and methoxamine [ME] were determined. Diabetic SHRs control had a higher basal mean arterial blood pressure than the WKY, lower RCBP and plasma adiponectin, higher creatinine clearance and urinary sodium excretion compared to WKY [all P<0.05] which were normalized by the individual drug treatments and to greater degree following combined treatment. Responses to intra-renal administration of NA, PE, ME and ANGII were larger in diabetic SHR than WKY and SHRs [P<0.05]. Adiponectin significantly blunted responses to NA, PE, ME and ANG II in diabetic treated SHRs by 40%, whereas the pioglitazone combined therapy with adiponectin further attenuated the responses to adrenergic agonists by 65%. [all P <0.05]. These findings suggest that adiponectin possesses renoprotective effects and improves renal haemodynamics through adiponectin receptors and PPAR-γ in diabetic SHRs, suggesting that synergism exists between adiponectin and pioglitazone. A cross-talk relationship also supposed to exists between adiponectin receptors, PPAR-γ and alpha adrenoceptors in renal vasculature of diabetic SHRs.

Hypoglycemic and hypolipidemic effects of two mangrove plants in a streptozotocin-induced animal model of diabetes

Objective:

This study aims at evaluating the anti-diabetic, hypolipidemic, and pancreatic histopathological changes of Rhizophora mucronata and Avicennia marina.

Materials and Methods:

The experimental rats were divided into eight groups (n = 15 each). Streptozotocin was used to induce diabetes. Daily oral administration of an aqueous extract from the leaves of R. mucronata and A. marina at 400 mg/kg BW, and a mixture of the two extracts for 6 weeks was assessed. The measurements of serum glucose, insulin, and lipid profile were carried out. Pancreatic specimens were collected from all groups and processed for pathological studies.

Results:

The study revealed that the plant extracts restored the levels of diabetic markers and lipid profiles of diabetic rats, with no significant changes in non-diabetic ones. The extract of R. mucronata exhibited more promising anti-diabetic and hypolipidemic effects than A. marina singly or combined.

Conclusion:

Leaf extracts from R. mucronata, singly or combined, and A. marina, induced a potent anti-diabetic and hypolipidemic potential in diabetic rats.

L, Durrani A. Environmentally benign PEG-OSO3H catalysed Ultrasound promoted cascade synthesis of furocoumarins in water

Background:

Green synthesis of furocoumarins in water, PEG-OSO3H used as a recyclable catalyst for the one-pot syntheis in water. avoid used of toxic, lachrymatric and unstablephenacyl bromides instead of that we prepared it in-situ and directly condence with 4-hydroxycoumarins.

Objective:

PEG-OSO3H found to be an efficient and reusable catalyst for the microwave irradiated one-pot synthesis of 3- Aryl-furo[3,2-c]coumarins in PEG-water as a greener reaction medium. This method found to be rapid, simple, ecofriendly and yield obtained relatively higher than other reported methods.

Methods:

Aromatic ketones (5 mmol), NBS (5mmol) was added in solution of PEG-OSO3H (10 mol%) in 10 ml water and irradiated under ultrasound at 80-85°C. then solution of 4-hydroxycoumarin (5 mmol) and solution of acetic acid and ammonium acetate (1 ml) were added into it. Reaction mass was further irradiated for 3 min. The reaction mixture was extracted with ethyl acetate (3 x 10ml) and the combined ethyl acetate phase was concentrated under reduced pressure to obtain corresponding 3-Aryl-furo[3,2-c]coumarins. Aqueous layer was reused for the next reactions.

Results:

It was observed that electrons withdrawing groups (-NO2,-F etc.) on benzene ring of aromatic ketones increases the rate of reactions as well as yield of the products. The IR spectrum of compound 4a showed prominent peaks at 1737cm-1C=O stretching for lactone, 1H NMR of compound 4c showed characteristic singlets for –CH3 of methoxy group of at 3.94 ppm, The above spectral data confirmed the structure of compound. The 13C NMR spectrum of 4b also shows the peaks of CH3, at 23.25 ppm.

Conclusion:

PEG-OSO3H found to be an efficient and reusable catalyst for the microwave irradiated one-pot synthesis of 3-Aryl-furo[3,2-c]coumarins in PEG-water as a greener reaction medium. This method found to be rapid, simple, ecofriendly and yield obtained relatively higher than other reported methods.

Stimulation of insulin secretion by 5-methylcoumarins and its sulfur analogues isolated from Clutia lanceolata Forssk

Clutia lanceolata Forssk. (C. lanceolata) is a medicinal plant native to sub-Saharan Africa and the Arabian Peninsula. Phytochemical investigation of the aerial parts of C. lanceolata yielded twenty-one coumarins including methylthio and methylsulfinyl-coumarins. Thirteen of these compounds are reported here for the first time, named as cluteolin A to M. The remaining eight compounds are known but have not been associated previously with C. lanceolata. The structures of the undescribed compounds were elucidated from their 2D NMR and MS spectra. Single crystal X-ray analyses confirmed the structures of eleven compounds. As, in Saudi Arabian tradition, C. lanceolata has been reported to have anti-diabetic and anti-fungal properties, the coumarins were examined for their biological activity. Seven compounds strongly enhanced the glucose-triggered release of insulin by murine pancreatic islets, with two compounds showing more than two-fold enhancement of insulin secretion, compared with the standard drug glimepiride.

Polyphenols from Stevia rebaudiana (Bertoni) leaves and their functional properties

The major polyphenol components from Stevia rebaudiana (Bertoni) leaves (PPS) are chlorogenic acids, a polyphenol family of esters, including hydroxycinnamic acids with quinic acid, which possesses excellent hydrophilic antioxidant activity and other therapeutic properties. As an abundant byproduct during production of steviol glycosides, the PPS would be a new antioxidantive food resource or additives applied in foods and drugs with antidiabetic function. Extracting PPS from S. rebaudiana (Bertoni) leaves together with steviol glycosides would be an economic process, which will change most operation process in current Stevia factories. The quantification of PPS needs to be unified for regulation. In view of the current regulation status of polyphenols and extracts from Stevia, the PPS would be ready to go to the market with few regulation barriers in the near future. This review will summarize the analysis, extraction, and some functional properties of PPS, such as antioxidant, antidiabetic, antimicrobial, anti-inflammatory, and anticancer.

Hesperidin, a citrus flavonoid ameliorates hyperglycemia by regulating key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats

The present study investigated the protective effect of hesperidin on carbohydrate metabolizing enzymes in streptozotocin-induced diabetic rats. Hesperidin was administered to streptozotocin-induced (40 mg/kg b.w.) diabetic rats at different dosages of (25, 50, 100 mg/kg b.w.) respectively for 30 days to evaluate its effect on fasting plasma glucose, insulin, glycosylated hemoglobin, hemoglobin, and carbohydrate metabolic enzymes. The plasma glucose levels were significantly reduced in a dose-dependent manner in hesperdin-treated group of rats when compared to the diabetic control rats. In addition, concomitant increase in hemoglobin and insulin levels and a decrease in glycosylated hemoglobin were observed in treated group of rats. The activities of the hepatic key enzymes of carbohydrate metabolism such as hexokinase and glucose-6-phosphate dehydrogenase were significantly increased, whereas glucose-6-phosphatase and fructose-1,6-bisphosphatase were significantly decreased. Furthermore, hesperidin administration prevented the loss in body weight and improved the glycogen content in the hepatic tissue of diabetic animals by reinstating the activities of glycogen synthase and glycogen phosphorylase. These results showed that hesperidin has potential antihyperglycemic activity in streptozotocin-induced diabetic rats. This was further supported by the histological studies of pancreas and liver.

Coumarin glycosides from Hydrangea paniculata slow down the progression of diabetic nephropathy by targeting Nrf2 anti-oxidation and smad2/3-mediated profibrosis

BACKGROUND

Water extract of Hydrangea paniculata (HP) stem, rich in coumarin glycosides, has been demonstrated to have renal protective effect in several experimental kidney injury animal models. Currently, it is under pre-clinical development as a class 5 herbal drug against membranous nephropathy. However, whether it also benefits diabetic nephropathy (DN) is not clear.

PURPOSE

This study was performed to investigate the protective effect of HP on streptozotocin-induced experimental DN, and further understand its molecular mechanisms.

METHODS

In the present study, type 1 diabetes rat model was established by the intraperitoneal injection of streptozotocin. HP was orally administered every day for three months. Biochemical analysis and histopathological staining were conducted to evaluate the renal functions. In vivo pharmacokinetic study was conducted to analyse the metabolites of HP with high blood drug concentration. In vitro assay using these metabolites was performed to analyse their ability to reduce reactive oxygen species (ROS) production induced under high glucose (HG) condition by flow cytometry. Reverse transcription-polymerase chain reaction was conducted to analyse the mRNA level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and IL6 and western blot was performed to analyse the phosphorylation status of smad 2/3 in HK2 cells under TGFβ1 stimulation.

RESULTS

The treatment with HP significantly reduced the blood urea nitrogen and serum creatinine content, and urine albumin excretion in diabetic rats, and increased the creatinine clearance rate. Periodic acid-schiff and methenamine staining and immunohistochemistry revealed that HP also ameliorated glomerulosclerosis and tubular vacuolar degeneration, as well as the deposition of fibronectin and collagen IV in the glomeruli. Pharmacokinetic study results revealed that the major coumarin compounds from HP were metabolised into umbelliferone and esculetin. By in vitro assay, umbelliferone and esculetin were found to significantly decrease ROS production induced by HG content, as well as increase the mRNA level of Nrf2. HP and its metabolites also can down-regulate fibronectin secretion in HK2 cells stimulated by TGFβ1 and inhibit smad2/3 phosphorylation.

CONCLUSION

HP has beneficial effect on DN by increasing Nrf2 expression and inhibiting TGF-smad signal activation. Further, it can be a novel herbal drug against DN.

Effects of citral on oxidative stress and hepatic key enzymes of glucose metabolism in streptozotocin/high-fat-diet induced diabetic dyslipidemic rats

OBJECTIVES

Phytochemicals such as polyphenols, alkaloids, and terpenoids, protect against the development of early stages and complications of diabetes mellitus according to various reports. The aim of this study was to measure the anti-dyslipidemic and anti-diabetic effects of Citral on high-fat-diet (HFD) and streptozotocin (STZ) induced diabetic dyslipidemic rats and to see also its effect on carbohydrate metabolic regulatory enzymes in the liver.

MATERIALS AND METHODS

Rats were kept on a high-fat diet for 2 weeks, then diabetes was induced by a single dose of STZ (35 mg/kg/BW, intraperitoneally), Citral was administered orally at a dose of 45 mg/kg/BW for 28 days to diabetic rats. Blood glucose, plasma insulin, and lipid profile in blood were studied. Antioxidant activities were assayed in the liver, pancreas, and adipose tissues. Carbohydrate metabolic enzymes of the liver were also studied in diabetic dyslipidemic rats.

RESULTS

The results of this study confirmed that administration of Citral significantly (P<0.05) decreased the blood glucose level and increased plasma insulin in diabetic rats. Citral also improved oxidative markers along with anti-oxidative enzymes of the liver, adipose tissue, and pancreas in the HFD/STZ group. Citral also regulated the activity of the glucose-metabolic enzymes in the liver. The results of the present study were compared to Glibenclamide, which is a standard oral drug for lowering the blood sugar.

CONCLUSION

Results may show that Citral possesses anti-dyslipidemic activity as well as anti-diabetic activity and also regulates the enzyme activity of glycolytic and gluconeogenic processes in the liver.

Action of corilagin on hyperglycemia, hyperlipidemia and oxidative stress in streptozotocin-induced diabetic rats

Diabetes mellitus is the world's most common endocrine disease involving metabolic disorders of carbohydrate, protein and fat. This study was undertaken to investigate the anti-diabetic activity of corilagin, a member of polyphenolic tannins used against hyperglycemia and many other diseases in well-known animal models. Diabetes was induced chemically by intraperitoneal administration of Streptozotocin (40 mg/kg bw) to albino Wistar rats. Diabetic rats showed significant increase in the levels of fasting blood glucose, glycated haemoglobin, total cholesterol, triglyceride, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, and a significant decrease in the level of body weight, plasma insulin, high density lipoprotein cholesterol, antioxidant activities, viz. superoxide dismutase, catalase and reduced glutathione when compared to controls. However, after 30 days of oral administration of corilagin (10 and 20 mg/kg bw/day) to these diabetic rats evoked significant alterations in the above mentioned parameters. The effect of corilagin was compared with the standard drug, glibenclamide (0.1 mg/kg body weight/day). Thus, the present study suggests that the corilagin acts as a natural, effective therapeutic agent to regulate diabetes, by exhibiting antidiabetic, antihyperlipidemic and antioxidant properties in STZ induced diabetic rats.

Antidiabetic and antihyperlipidemic effects of ethanolic Ferula assa-foetida oleo-gum-resin extract in streptozotocin-induced diabetic wistar rats

The present study was conducted to investigate the hypoglycemic and hypolipidemic activity of ethanolic ferula assa-foetida oleo-gum-resin extract (FAOGRETE) and also its effects on liver and kidney function in streptozotocin (STZ)-induced diabetic rats. For this purpose, 42 male Wistar rats were divided into six groups (n = 7). Diabetes was induced in four groups by a single-dose of STZ at 55 mg/kg body weight, administrated intraperitoneal. After 42 days of treatment, fasting blood sugar (FBS) levels, serum insulin, biochemical parameters such as total cholesterol, triglycerides, low and high density lipoprotein cholesterol were measured. In addition the markers of liver and kidney function, such as glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase, serum creatinine and urea levels were determined. The study showed that the ethanolic extract at 150 mg/kg body weight (b.w) had a significant antidiabetic activity after 42 days of treatment as the FBS levels decreased significantly while the serum insulin levels increased. Moreover, a significant decrease in the liver and kidney function markers in treated rats indicated the protective effect of the ethanolic extract against liver and kidney damage, while body weight increased. The serum concentrations were normal in normal control and healthy group treated with FAOGRETE. The results of this study showed that FAOGRETE can regulate hyperglycemia and complications of diabetes. Antidiabetic and hypolipidimic activities of FAOGRETE are probably related to its antioxidant activity. Phenolic and flavonoid compounds like ferulic acid, umbelliferone, and quercetin may play an important role in its mechanism of action.

Synthesis and biological evaluation of 3-arylcoumarin derivatives as potential anti-diabetic agents

A variety of substituted 3-arylcoumarin derivatives were synthesised through microwave radiation heating. The method has characteristics of environmental friendliness, economy, simple separation, and purification process, less by-products and high reaction yield. Those 3-arylcoumarin derivatives were screened for antioxidant, α-glucosidase inhibitory and advanced glycation end-products (AGEs) formation inhibitory. Most compounds exhibited significant antioxidant and AGEs formation inhibitory activities. Anti-diabetic activity studies showed that compounds 11 and 17 were equipotent to the standard drug glibenclamide in vivo. According to the experimental results, the target compound 35 can be used as a lead compound for the development of new anti-diabetic drugs. The whole experiment showed that anti-diabetic activity is prevalent in 3-arylcoumarins, which added a new natural skeleton to the development of anti-diabetic active drugs.

The response of serum Glypican-4 levels and its potential regulatory mechanism to endurance training and chamomile flowers' hydroethanolic extract in streptozotocin-nicotinamide-induced diabetic rats

AIMS

Glypican-4 (GPC-4) is a novel adipomyokine that enhances insulin signaling. Glycosylphosphatidylinositol-specific phospholipase D (GPLD1) is thought to release GPC-4 and is itself an insulin-regulated enzyme. Beneficial effects of exercise training and chamomile flowers extract (CFE) are shown through activation of PPARγ, which is a promising drug target in diabetes and associated with GPC-4 synthesis. This study investigated the effects of 14-week treadmill running and CFE on serum GPC-4, GPLD1, and insulin levels in streptozotocin-nicotinamide (STZ-NA)-induced diabetic rats.

METHODS

Thirty-two STZ-NA-induced diabetic male Wistar rats were randomly assigned to four groups: control (C), training (T), CFE treatment (CFE), and training plus CFE treatment (TCFE) groups. The training groups were exercised on treadmill 5 days/week and the treating groups were fed with 200 mg/kg/day CFE in drinking water for 14 weeks. Finally, serum GPC-4, GPLD1, and insulin levels were analyzed via sandwich ELISA.

RESULTS

Compared to the control group, serum insulin levels were significantly higher in the T, CFE, and TCFE groups (p < 0.05, p < 0.05, p < 0.01, respectively), while OGTT and serum GPLD1 levels were significantly lower in the T, CFE, and TCFE groups (all p < 0.001). Changes in serum GPC-4 levels were not significant. Serum GPLD1 levels were negatively correlated with insulin levels and HOMA-IS (both p < 0.001).

CONCLUSIONS

This study suggests that endurance training and CFE may downregulate serum GPLD1 levels in STZ-NA-induced diabetic rats, which associate with the serum insulin profile. However, the results show that endurance training and CFE may not cause serum GPC-4 adaptation in STZ-NA-induced diabetic rats.

Anti diabetic property of aqueous extract of Stevia rebaudiana Bertoni leaves in Streptozotocin-induced diabetes in albino rats

BACKGROUND

Stevia (Stevia rebaudiana) natural, non-caloric sugar substitute is rich source of pharmacologically important glycoside stevioside that is linked to the pathology and complications of diabetes.

METHODS

The current research was carried out to explore the anti-diabetic effect of aqueous extract of Stevia rebaudiana leaves in albino rats. For this purpose, diabetes was induced by administration of streptozotocin (40 mg/kg body weight, intraperitoneally). The diabetic rats were administered with aqueous stevia extract at different dose levels (200, 300, 400 and 500 ppm/kg b.w) for 8 weeks; the control rats were fed basal diet during this period.

RESULTS

Stevia aqueous extract improved caloric management and weight control by decreasing the feed intake and body weight gain. Furthermore, intake of stevia extract resulted in significant (P < 0.05) decrease in the random blood glucose level (- 73.24%) and fasting blood glucose (- 66.09%) and glycosylated (HbA1c) hemoglobin (5.32%) while insulin (17.82 μIU/mL) and liver glycogen (45.02 mg/g) levels significantly improved in the diabetic rats, compared with the diabetic and non-diabetic control rats after 8 weeks study period.

CONCLUSIONS

It is concluded that aqueous extact of stevia has anti-diabetic effects in albino rats, and therefore could be promising nutraceutical therapy for the management of diabetes and its associated complications.

Leea macrophylla Roxb. leaf extract potentially helps normalize islet of β-cells damaged in STZ-induced albino rats

This research aims to investigate the protective effects Leea macrophylla Roxb polyphenols on streptozotocin-induced diabetic rats. Polyphenolic assays were undertaken through established methods. To conduct animal intervention study, forty Wistar albino male rats (average body weight 188.42 ± 7.13 g) of different groups were diabetized by streptozotocin (60 mg/kg) only in the animals of diabetic control (DC) and L. macrophylla extract (LM) groups. At the end of 4 weeks of intervention, serum was analyzed for insulin, liver and cardiac enzymes, lipid profiles, uric acid, and creatinine using ELISA method. In vitro α-amylase inhibition of LM was evaluated and compared with reference drug acarbose. Pancreatic tissues were undertaken for histopathological screening. Food and fluid intake, weekly blood glucose level, liver glycogen, aspartate transaminase (AST), creatinine kinase (CK-MB), cholesterol, and lactate dehydrogenase (LDH) were significantly decreased, whereas oral glucose tolerance (OGTT) ability, serum insulin concentration, and pancreatic islets morphology were significantly improved in the LM300 treatment group compared to the DC group. Alpha-amylase inhibition was not found to be very promising for guiding the α-amylase inhibition pathway. Results suggest that L. macrophylla can exert a potential effort to restore pancreatic β-cell damaged by streptozotocin induction.

Anti-Diabetic Effect of Cotreatment with Quercetin and Resveratrol in Streptozotocin-Induced Diabetic Rats

Quercetin and resveratrol are known to have beneficial effects on the diabetes and diabetic complication, however, the effects of combined treatment of these compounds on diabetes are not fully revealed. Therefore, the present study was designed to investigate the combined antidiabetic action of quercetin (QE) and resveratrol (RS) in streptozotocin (STZ)-induced diabetic rats. To test the effects of co-treated with these compounds on diabetes, serum glucose, insulin, lipid profiles, oxidative stress biomarkers, and ions were determined. Additionally, the activities of hepatic glucose metabolic enzymes and histological analyses of pancreatic tissues were evaluated. 50 male Sprague-Dawley rats were divided into five groups; normal control, 50 mg/kg STZ-induced diabetic, and three (30 mg/kg QE, 10 mg/kg RS, and combined) compound-treated diabetic groups. The elevated serum blood glucose levels, insulin levels, and dyslipidemia in diabetic rats were significantly improved by QE, RS, and combined treatments. Oxidative stress and tissue injury biomarkers were dramatically inhibited by these compounds. They also shown to improve the hematological parameters which were shown to the hyperlactatemia and ketoacidosis as main causes of diabetic complications. The compounds treatment maintained the activities of hepatic glucose metabolic enzymes and structure of pancreatic β-cells from the diabetes, and it is noteworthy that cotreatment with QE and RS showed the most preventive effect on the diabetic rats. Therefore, our study suggests that cotreatment with QE and RS has beneficial effects against diabetes. We further suggest that cotreatment with QE and RS has the potential for use as an alternative therapeutic strategy for diabetes.

Effects of different aerobic exercise frequencies on streptozotocin-nicotinamide-induced type 2 diabetic rats: Continuous versus short bouts and weekend warrior exercises

BACKGROUND

Exercise training is known to have multiple beneficial effects on type 2 diabetes mellitus (T2DM). The aim of this study was to explore the effects of aerobic exercise frequency on diabetic parameters, the histopathological structure of skeletal muscle, diabetic myopathy, and mitochondrial enzyme activity in an experimental model of T2DM.

METHODS

Sprague-Dawley rats (n = 35) were rendered diabetic by injection of nicotinamide (110 mg/kg) and streptozotocin (65 mg/kg). Rats with blood glucose concentrations between 7 and 17 mmol/L were used. Diabetic rats were randomly allocated to one of the following groups: (i) control sedentary; (ii) diabetic sedentary; (iii) diabetic with continuous exercise (30 min/day, 5 days/week); (iv) diabetic with short bouts of exercise (3 × 10 min/day, 5 days/week); and (v) diabetic rats as "weekend warriors" (35 + 40 min/day, 2 days/week). After 6 weeks swimming exercise (total duration 150 min/week), biochemical tests were performed to measure insulin, glucose, cytokines, serum and muscle myeloperoxidase (MPO), and malondialdehyde (MDA) levels. Histologic analysis (histomorphometric and mitochondrial enzyme analysis) was also performed.

RESULTS

Compared with diabetic sedentary rats, significant improvements were observed in all exercise groups in terms of glucose levels, weight loss, tissue MPO and MDA levels, muscular connective tissue, muscle atrophy, mitochondrial enzyme, and all histomorphometric analyses.

CONCLUSIONS

The results of the study emphasize the effects of training on inflammation, increased oxidative stress, myopathy, and mitochondrial damage in a rat model of T2DM, and demonstrate that there is no major difference between exercise modalities provided that the total duration of exercise remains the same.

Vinpocetine mitigates proteinuria and podocytes injury in a rat model of diabetic nephropathy

Podocyte injury and glomerular basement membrane thickening have been considered as essential pathophysiological events in diabetic nephropathy. The aim of this study was to investigate the possible beneficial effects of vinpocetine on diabetes-associated renal damage. Male Wistar rats were made diabetic by injection of streptozotocin (STZ). Diabetic rats were treated with vinpocetine in a dose of 20mg/kg/day for 6 weeks. Treatment with vinpocetine resulted in a marked decrease in the levels of blood glucose, glycosylated haemoglobin, creatinine, blood urea nitrogen, urinary albumin and albumin/creatinine ratio along with an elevation in creatinine clearance rate. The renal contents of advanced glycation end-products, interleukin-10, tissue growth factor-β, nuclear factor (NF)-κB and Ras-related C3 botulinum toxin substrate 1 (Rac 1) were decreased. Renal nephrin and podocin contents were increased and their mRNA expressions were replenished in vinpocetine-treated rats. Moreover, administration of vinpocetine showed improvements in oxidative status as well as renal glomerular and tubular structures. The current investigation revealed that vinpocetine ameliorated the STZ-induced renal damage. This beneficial effect could be attributed to its antioxidant and antihyperglycemic effects parallel to its ability to inhibit NF-κB which eventually modulated cytokines production as well as nephrin and podocin proteins expression.

Coumarins as potential antidiabetic agents

OBJECTIVES

Even with great advances in modern medicine and therapeutic agent development, the search for effective antidiabetic drugs remains challenging. Coumarins are secondary metabolites found widely in nature plants and used mainly in anticoagulation and antithrombotic therapy. Over the past two decades, however, there has been an increasing body of literatures related to the effects of coumarins and their derivatives on diabetes and its complications. This review aimed to focus on research findings concerning the effects of coumarins against diabetes and its complications using in-vitro and in-vivo animal models, and also to discuss cellular and molecular mechanisms underlying these effects.

KEY FINDINGS

The search for new coumarins against diabetes and it complications, either isolated from traditional medicine or chemically synthesized, has been constantly expanding. The cellular and molecular mechanisms involved include protecting pancreatic beta cells from damage, improving abnormal insulin signalling, reducing oxidative stress/inflammation, activating AMP-activated protein kinase (AMPK), inhibiting α-glucosidases and ameliorating diabetic complications.

CONCLUSIONS

The effects and mechanisms of coumarins and their derivatives upon diabetes and its complications are discussed in current review. Further investigations remain to be carried out to develop a promising antidiabetic agent based on coumarin cores.

Dillenia indica L. attenuates diabetic nephropathy via inhibition of advanced glycation end products accumulation in STZ-nicotinamide induced diabetic rats

The present study was aimed to evaluate advanced glycation end products (AGEs) inhibitory activity of alcohol and hydro-alcohol extract (DAE and DHE) of Dillenia indica L. (Family: Dilleniaceae) and its potential in treatment of diabetic nephropathy by targeting markers of oxidative stress. D. indica was evaluated for its in vitro inhibitory activity against formation of AGEs by using bovine serum albumin. Diabetes was induced in male Wistar rats by streptozotocin (65 mg/kg i.p.) 15 min after nicotinamide (230 mg/kg, i.p.) administration. Diabetic rats were treated with different doses of extracts (100, 200 and 400 mg/kg) to analyze their nephroprotective effect. Tissue antioxidant enzymes level was measured along with the formation of AGEs in kidney to assess the effect of D. indica in ameliorating oxidative stress. D. indica showed significant inhibition of AGEs formation in vitro. D. indica produced significant attenuation in the glycemic status, renal parameter, lipid profile and level of antioxidant enzymes proving efficacy in diabetic nephropathy. Moreover, D. indica produced significant reduction in the formation of AGEs in kidneys. The present study concludes that D. indica as a possible therapeutic agent against diabetic nephropathy.

Averrhoa bilimbi fruits attenuate hyperglycemia-mediated oxidative stress in streptozotocin-induced diabetic rats

Hyperglycemia-mediated oxidative stress plays a major role in the development of diabetic complications. Averrhoa bilimbi Linn. (Oxalidaceae) is a medicinal plant with fruits reported to possess antidiabetic activity. This study evaluated the beneficial effects of the ethyl acetate fraction of A. bilimbi fruit (ABAEE) on the antioxidant/oxidant status in diabetes mellitus. Diabetic rats were treated orally with the ethyl acetate fraction of A. bilimbi fruits at a dose of 25 mg/kg body weight for 60 days. Serum glucose, glycated hemoglobin, plasma insulin, hepatic toxicity markers, antioxidant enzymes, lipid peroxidation products, and liver histopathology were assayed checked after 60 days of extract treatment. Diabetic rats administered ABAEE showed a significant decline in serum glucose, glycated hemoglobin, and also significantly increases the level of plasma insulin, as well as a notable attenuation in thiobarbituric acid-reactive substances, conjugated dienes, and hydroperoxides. ABAEE also modulated hepatic antioxidant potential by significantly increasing the activities of catalase, glutathione peroxidase, glutathione reductase, superoxide dismutase, and reducing glutathione content. The results associated with ABAEE were more significant than those observed following treatment with the standard drug metformin. Histopathological observations showed that ABAEE effectively rescued hepatocytes from oxidative damage without affecting cellular function and structural integrity. High-performance liquid chromatography analysis of ABAEE indicated the presence of phenolic compound, quercetin, indicating that the anti-diabetic effect of the extract might be related to quercetin. These results demonstrated the potential beneficial effect of ABAEE on streptozotocin-induced diabetes in rats.