Protective effect of quercetin on the morphology of pancreatic beta-cells of streptozotocin-treated diabetic rats

Natural Functional Beverages as an Approach to Manage Diabetes

Diabetes mellitus is a chronic disease, commonly associated with unhealthy habits and obesity, and it is becoming a serious health issue worldwide. As a result, new approaches to treat diabetes are required, and a movement towards more natural approaches is emerging. Consuming fruit and vegetables is advised to prevent diabetes since they contain several bioactive compounds. A simple and effective strategy to include them in the diets of diabetic and obese people is through beverages. This review aims to report the anti-diabetic potentials of different vegetable and fruit beverages. These functional beverages demonstrated in vitro potential to inhibit α-glucosidase and α-amylase enzymes and to improve glucose uptake. In vivo, beverage consumption showed a reduction of blood glucose, increase of insulin tolerance, improvement of lipid profile, control of obesity, and reduction of oxidative stress. This suggests the potential of vegetable- and fruit-based functional beverages to be used as a natural innovative therapy for the management of diabetes.

Binding mechanism and biological effects of flavone DYRK1A inhibitors for the design of new antidiabetics

The selective inhibition of kinases from the diabetic kinome is known to promote the regeneration of beta cells and provide an opportunity for the curative treatment of diabetes. The effect can be achieved by carefully tailoring the selectivity of inhibitor toward a particular kinase, especially DYRK1A, previously associated with Down syndrome and Alzheimer's disease. Recently DYRK1A inhibition has been shown to promote both insulin secretion and beta cells proliferation. Here, we show that commonly available flavones are effective inhibitors of DYRK1A. The observed biochemical activity of flavone compounds is confirmed by crystal structures solved at 2.06 Å and 2.32 Å resolution, deciphering the way inhibitors bind in the ATP-binding pocket of the kinase, which is driven by the arrangement of hydroxyl moieties. We also demonstrate antidiabetic properties of these biomolecules and prove that they could be further improved by therapy combined with TGF-β inhibitors. Our data will allow future structure-based optimization of the presented scaffolds toward potent, bioavailable and selective anti-diabetic drugs.

Protective effects of cardamom aqueous extract against tamoxifen-induced pancreatic injury in female rats

Tamoxifen (TAM) is a commonly used drug for breast cancer treatment. Although effective, TAM has deleterious effects on many organs. The toxic effects of TAM on the pancreas and the underlying mechanisms however, have not fully investigated. In the present study, we investigated the effects of TAM on the pancreatic tissue in female rats. We also examined whether cardamom aqueous extract (CAE) protects against TAM-induced pancreatic injury. TAM-intoxicated rats were injected with 45 mg/kg of TAM for 10 days, whereas rats in the CAE-treated group were administered 10 mL/kg of CAE for 20 days, starting 10 days prior to TAM administration. Treatment with TAM resulted in severe degeneration of the pancreatic acini and marked increases in the serum levels of pancreatic lipase, α-amylase, glucose, fatty acids and triglycerides along with decreased insulin serum levels. TAM led to oxidative stress as evident from a significant increase in the pancreatic levels of lipid peroxides and nitric oxide along with the depletion of reduced glutathione, glutathione peroxidase, and superoxide dismutase. Moreover, inflammation was indicated by a significant increase in tumor necrosis factor-α and interleukin-6 levels, enhanced expression of the macrophage recruitment marker; CD68 as well as up-regulated protein levels of toll-like receptor 4 and nuclear factor kappa B and increased p-p38/MAPK ratio; which are important signals in the production of inflammatory cytokines. TAM also markedly increased the pancreatic levels of caspase-3 and BAX reflecting its apoptotic effects. The CAE treatment ameliorated all the biochemical and histological changes induced by TAM. The present study revealed, for the first time, that TAM has toxic effects on the pancreatic tissue through oxidative stress, inflammation and apoptotic effects. The present study also provides evidence that CAE exerts cytoprotective effects against these deleterious effects induced by TAM in the pancreatic tissue.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00198-w.

Therapeutic Potential of Quercetin in the Management of Type-2 Diabetes Mellitus

Diabetes Mellitus (DM) is a metabolic disorder that is spreading alarmingly around the globe. Type-2 DM (T2DM) is characterized by low-grade inflammation and insulin resistance and is closely linked to obesity. T2DM is mainly controlled by lifestyle/dietary changes and oral antidiabetic drugs but requires insulin in severe cases. Many of the drugs that are currently used to treat DM are costly and present adverse side effects. Several cellular, animal, and clinical studies have provided compelling evidence that flavonoids have therapeutic potential in the management of diabetes and its complications. Quercetin is a flavonoid, present in various natural sources, which has demonstrated in vitro and in vivo antidiabetic properties. It improves oral glucose tolerance, as well as pancreatic β-cell function to secrete insulin. It inhibits the α-glucosidase and DPP-IV enzymes, which prolong the half-life of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Quercetin also suppresses the release of pro-inflammatory markers such as IL-1β, IL-4, IL-6, and TNF-α. Further studies are warranted to elucidate the mode(s) of action of quercetin at the molecular level. This review demonstrates the therapeutic potential of quercetin in the management of T2DM.

Elucidating the Neuroprotective Effect of Tecoma stans Leaf Extract in STZ-Induced Diabetic Neuropathy

Background

Diabetes is considered one of the most encyclopedic metabolic disorders owing to an alarming rise in the number of patients, which is increasing at an exponential rate. With the current therapeutics, which only aims to provide symptomatic and momentary relief, the scientists are shifting gears to explore alternative therapies which not only can target diabetes but can also help in limiting the progression of diabetic complications including diabetic neuropathy (DN).

Methods

Tecoma stans leaf methanolic extract was prepared using the Soxhlet method. A streptozotocin (STZ; 45 mg/kg)-induced diabetic animal model was used and treatment with oral dosing of T. stans leaf extract at the different doses of 200 mg/kg, 300 mg/kg, and highest dose, i.e., 400 mg/kg, was initiated on day 3 after STZ administration. The pharmacological response for general and biochemical (angiogenic, inflammatory, and oxidative) parameters and behavioral parameters were compared using Gabapentin as a standard drug with the results from the test drug.

Results

Parameters associated with the pathogenesis of diabetic neuropathy were evaluated. For general parameters, different doses of T. stans extract (TSE) on blood sugar showed significant effects as compared to the diabetic group. Also, the results from biochemical analysis and behavioral parameters showed significant positive effects in line with general parameters. The combination therapy of TSE at 400 mg/kg with a standard drug produced nonsignificant effects in comparison with the normal group.

Conclusion

The leaves of T. stans possess antidiabetic effects along with promising effects in the management of DN by producing significant effects by exhibiting antioxidative, antiangiogenic, and anti-inflammatory properties, which are prognostic markers for DN, and thus, T. stans can be considered as an emerging therapeutic option for DN.

Protective Effects of Quercetin on Clothianidin-Induced Liver Damage in the Rat Model

Clothianidin (CTD) is a member of the neonicotinoid group of insecticides. This study was performed to determine the effect of quercetin on clothianidin-induced liver injury (CTD) in rats. Rats were randomly assigned to a normal control (saline), a CTD control-treated group (20 mg/kg) every 3 days for 21 days, and CTD + quercetin-treated groups (2.5, 5, and 10 mg/kg) for 35 days intraperitoneally. Enzyme activity, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), was measured by spectrophotometry in serum samples by an automatic biochemical analyzer using commercial kits. Total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrate-nitrite were measured in homogeneous liver tissue samples of animals. A significant increase in ALT and AST enzyme activity was observed in the CTD group in comparison with that of the control groups. In the clothianidin + quercetin (10 mg/kg) group, the ALT and AST enzyme levels decreased compared to the clothianidin control group significantly (P < 0.05). The MDA value of the liver increased in the clothianidin-treated group compared to that of the control groups (P < 0.05). Decreased tissue TAC level was observed in the CTD-treated group in comparison with that of the control groups (P < 0.05). The MDA level of the liver decreased in the clothianidin + quercetin (10 mg/kg) group compared to that of the CTD control group (P < 0.05). Quercetin significantly raised the level of TAC in the liver tissue of the clothianidin + quercetin (10 mg/kg) treated group compared to that of the clothianidin control group (P < 0.05). Liver nitrate-nitrite measurement showed a significant increase in the clothianidin group compared to that of the normal control group (P < 0.05). Nitrate-nitrite level in the liver was decreased in clothianidin + quercetin (10 mg/kg) compared to that of the clothianidin control group significantly (P < 0.05). Histopathological investigation revealed that contact to the CTD induced tissue disorganization and inflammatory cell infiltration, but minor histopathological alterations in the liver tissues of rats treated with CTD and quercetin (10 mg/kg) were detected.

Botanical Interventions to Improve Glucose Control and Options for Diabetes Therapy

Diabetes mellitus is a major public health problem worldwide. This endocrine disease is clustered into distinct subtypes based on the route of development, with the most common forms associated with either autoimmunity (T1DM) or obesity (T2DM). A shared hallmark of both major forms of diabetes is a reduction in function (insulin secretion) or mass (cell number) of the pancreatic islet beta-cell. Diminutions in both mass and function are often present. A wide assortment of plants have been used historically to reduce the pathological features associated with diabetes. In this review, we provide an organized viewpoint focused around the phytochemicals and herbal extracts investigated using various preclinical and clinical study designs. In some cases, crude extracts were examined directly, and in others, purified compounds were explored for their possible therapeutic efficacy. A subset of these studies compared the botanical product with standard of care prescribed drugs. Finally, we note that botanical formulations are likely suspects for future drug discovery and refinement into class(es) of compounds that have either direct or adjuvant therapeutic benefit.

Effects of Fermented Houttuynia cordata Thunb. on Diabetic Rats Induced by a High-Fat Diet with Streptozotocin and on Insulin Resistance in 3T3-L1 Adipocytes

Houttuynia cordata Thunb. (plukaow in Thai language) exhibits several biological properties, and many products of H. cordata are therefore commercially available for human consumption, such as fermented juice or tablets as food supplements. This study aimed to investigate the antidiabetic effects of fermented H. cordata (HC) in high-fat diets and streptozotocin-induced diabetic rats. Oral administration of HC at a dose of 100 mg/kg.bw not only maintained bodyweight, food intake, and water consumption but also reduced blood glucose levels and improved glucose tolerance ability in the diabetic rats. Moreover, HC also decreased oxidative stress markers in serum and inflammatory-related mediators in pancreas tissues, indicating the improvement of pancreatic beta-cell function in the diabetic rats. In order to clarify the mechanism of HC, the effects of ethanolic extract of HC (HCE) on insulin resistance were determined in 3T3-L1 adipocytes. FHE could recover glucose uptake and decrease lipolysis in palmitate-treated 3T3-L1 adipocytes. Taken together, these results demonstrate that HC can improve diabetic symptoms by enhancing insulin sensitivity, reducing oxidative stress, and suppressing inflammation.

The Therapeutic Effects and Mechanisms of Quercetin on Metabolic Diseases: Pharmacological Data and Clinical Evidence

Metabolic diseases have become major public health issues worldwide. Searching for effective drugs for treating metabolic diseases from natural compounds has attracted increasing attention. Quercetin, an important natural flavonoid, is extensively present in fruits, vegetables, and medicinal plants. Due to its potentially beneficial effects on human health, quercetin has become the focus of medicinal attention. In this review, we provide a timely and comprehensive summary of the pharmacological advances and clinical data of quercetin in the treatment of three metabolic diseases, including diabetes, hyperlipidemia, and nonalcoholic fatty liver disease (NAFLD). Accumulating evidences obtained from animal experiments prove that quercetin has beneficial effects on these three diseases. It can promote insulin secretion, improve insulin resistance, lower blood lipid levels, inhibit inflammation and oxidative stress, alleviate hepatic lipid accumulation, and regulate gut microbiota disorders in animal models. However, human clinical studies on the effects of quercetin in diabetes, hyperlipidemia, and NAFLD remain scarce. More clinical trials with larger sample sizes and longer trial durations are needed to verify its true effectiveness in human subjects. Moreover, another important issue that needs to be resolved in future research is to improve the bioavailability of quercetin. This review may provide valuable information for the basic research, drug development, and clinical application of quercetin in the treatment of metabolic diseases.

Tribulus terrestris Efficacy and Safety Concerns in Diabetes and Erectile Dysfunction, Assessed in an Experimental Model

The present project aims to evaluate Tribulus terrestris (TT) extracts by addressing various possible mechanisms of action in order to see whether the use of TT supplements in diabetes and diabetes complications is justified. Diabetic rats were divided into three groups: diabetic control group, TT extract with low protodioscin content group (TT-LPC) and TT extract with high protodioscin content group (TT-HPC). After twelve weeks of treatment, fasting blood glucose, insulin, LH, FSH and testosterone levels were measured. Both TT preparations reduced elevated blood glucose level. Insulin and luteinizing hormone levels were not significantly different compared with the control group; however, the FSH and testosterone levels were significantly higher in the TT-HPC group compared with the diabetic control group. The testosterone level is correlated in part with the protodioscin concentration in extracts and is probably mediated through an FSH-linked pathway.

Thymoquinone Preserves Pancreatic Islets Structure Through Upregulation of Pancreatic β-Catenin in Hypothyroid Rats

BACKGROUND

Altered status of thyroid hormones, which have a key role in regulating metabolism, was reported to affect glucose homeostasis and insulin secretion.

OBJECTIVE

This study was designed to assess the impact of propylthiouracil (PTU)-induced hypothyroidism on the pancreatic islet cells and the efficacy of thymoquinone (TQ) in alleviating this impact and explore the mechanism behind it alleviating oxidative stress and affecting β-catenin expression.

MATERIALS AND METHODS

PTU (6 mg/kg/body weight) was used to induce hypothyroidism in Wistar rats. Four groups of rats (n=6 each) were utilized in this study. Untreated hypothyroid and TQ-treated hypothyroid groups (50 mg/kg/body weight for 4 weeks) were included. Thyroid functions, antioxidant profile and pancreatic β-catenin and IL-10 mRNA were measured. Histopathological and immunohistochemical assessment of the pancreas was performed.

RESULTS

PTU administration induced a hypothyroid status that was associated with a marked disturbed oxidant/antioxidant status and a significant hyperglycemia (p<0:001), hypoinsulinemia (p=0.01) and decreased HOMA-β-cell (p<0.001). Islet cells of hypothyroid pancreas showed many degenerative changes with increased apoptosis, reduced insulin β-catenin immunoexpression. Administration of TQ alleviated these effects on the thyroid function, antioxidants, structure of pancreatic islet cells. Up-regulation of β-catenin, IL-10 and CAT gene expression in pancreatic islets after treatment with TQ supported its antioxidant and preserving β-cell function and viability mechanistic action.

CONCLUSION

TQ alleviated PTU-induced hypothyroidism changes in insulin homeostasis and pancreatic β cells mostly through its antioxidant effect as well as up-regulation of pancreatic β-catenin expression.

Date palm fruit extract ameliorated pancreatic apoptosis, endocrine dysfunction and regulatory inflammatory cytokines in Streptozotocin-induced diabetes in rats

The current work studied the mechanism(s) and ability by which date palm (Phoenix dactylifera L.) fruit extract (DPE) inspired a glucose-lowering impact in rats suffering from diabetes. Forty-eight albino rats were divided into six various experimental treatments after induction of diabetes by intraperitoneal infusion of streptozotocin (45 mg/kg bwt) as follows: normal control, DPE, diabetic control, diabetic glibenclamide (GLI), diabetic DPE, and diabetic GLI plus DPE-treated groups. In animals euthanized after 8 weeks, blood and pancreatic tissue samples were assembled to assess different biochemical and histopathological changes. The expressions of insulin, B cell lymphoma-2 (Bcl-2), and cysteine aspartate-specific protease-3 (caspase-3) in islet β cells were also evaluated using immunohistochemical assessment. Diabetic rats exhibited hyperglycemia; increment of pancreatic malondialdehyde (lipid peroxidation biomarker), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β); and decrement of plasma insulin and pancreatic antioxidants: glutathione, superoxide dismutase, and catalase values. Also, the pancreatic islets exhibited histopathological and morphometric alternations associated with weak positive insulin and Bcl-2 immunoreactivity and strong positive caspase-3 immunoreactivity. DPE and/or GLI, an anti-diabetic drug, improved the pancreatic histoarchitecture and improved β cell function and structure, which increased insulin levels and improved the insulin, Bcl-2, and caspase-3 immunoreactivity in diabetic rats. Nevertheless, the combined DPE and GLI therapy revealed a significant recovery and restoration of β cells' structure and function. The date palm fruit has anti-apoptotic, anti-inflammatory, and antioxidant activities and hypoglycemic effects, which in turn play a pivotal role in avoiding the progression of diabetes mellitus. Moreover, it could potentiate the glucose-lowering activity of anti-diabetic drugs.

A Review on Oxidative Stress, Diabetic Complications, and the Roles of Honey Polyphenols

Despite the availability of various antidiabetic drugs, diabetes mellitus (DM) remains one of the world's most prevalent chronic diseases and is a global burden. Hyperglycaemia, a characteristic of type 2 diabetes mellitus (T2DM), substantially leads to the generation of reactive oxygen species (ROS), triggering oxidative stress as well as numerous cellular and molecular modifications such as mitochondrial dysfunction affecting normal physiological functions in the body. In mitochondrial-mediated processes, oxidative pathways play an important role, although the responsible molecular mechanisms remain unclear. The impaired mitochondrial function is evidenced by insulin insensitivity in various cell types. In addition, the roles of master antioxidant pathway nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)/antioxidant response elements (ARE) are being deciphered to explain various molecular pathways involved in diabetes. Dietary factors are known to influence diabetes, and many natural dietary factors have been studied to improve diabetes. Honey is primarily rich in carbohydrates and is also abundant in flavonoids and phenolic acids; thus, it is a promising therapeutic antioxidant for various disorders. Various research has indicated that honey has strong wound-healing properties and has antibacterial, anti-inflammatory, antifungal, and antiviral effects; thus, it is a promising antidiabetic agent. The potential antidiabetic mechanisms of honey were proposed based on its major constituents. This review focuses on the various prospects of using honey as an antidiabetic agent and the potential insights.

Antidiabetic and antihyperlipidemic effects of Argyreia pierreana and Matelea denticulata: Higher activity of the micellar nanoformulation over the crude extract

Background and aim

Herbal medicine combined with nanotechnology is widely proposed to improve the oral bioavailability, reduce the required dose and side effects, and improve the pharmacological efficacy of extracts. Thus, this study evaluated the in vivo antidiabetic and antihyperlipidemic activities of ethanolic leaf extracts of Argyreia pierreana (AP) and Matelea denticulata (MP) plants in comparison with their micellar nanoformulations.

Materials and methods

The mixed micelles (MMs) loaded with crude extracts (CEs) of AP and MD (AP-MMs and MD-MMs) were prepared using a film dispersion technique. Type 2 diabetes was induced in rats using high-fat diet (HFD) and low-dose (35 mg/kg) streptozotocin (STZ) injection. The pharmacological actions of CEs, AP-MMs and MD-MMs were determined in type 2 diabetic Sprague-Dawley rats.

Results

Oral treatments with low-dose AP-MMs and MD-MMs having a mean particle size of 163 ± 10 nm and 145 ± 8 nm respectively, resulted in significantly decreased fasting blood glucose level and increased serum insulin, glucokinase levels, and normalized the elevated levels of hemoglobin A1C and glucose-6-phosphatase. Both extracts significantly decreased serum total cholesterol, triglycerides, and low-density lipoprotein, as well as elevated high-density lipoprotein levels. Additionally, improvements in antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and malondialdehyde levels were evidenced clearly in tested vital organs (brain, heart, liver).

Conclusion

This is the first report of the antidiabetic and antihyperlipidemic activities of ethanolic leaf extracts of AP and MP plants. Our findings indicate the potential utility of nanotechnology in improving the oral therapeutic efficacy of herbal extracts.

Therapeutic Potential of Quercetin: New Insights and Perspectives for Human Health

Quercetin (Que) and its derivatives are naturally occurring phytochemicals with promising bioactive effects. The antidiabetic, anti-inflammatory, antioxidant, antimicrobial, anti-Alzheimer's, antiarthritic, cardiovascular, and wound-healing effects of Que have been extensively investigated, as well as its anticancer activity against different cancer cell lines has been recently reported. Que and its derivatives are found predominantly in the Western diet, and people might benefit from their protective effect just by taking them via diets or as a food supplement. Bioavailability-related drug-delivery systems of Que have also been markedly exploited, and Que nanoparticles appear as a promising platform to enhance their bioavailability. The present review aims to provide a brief overview of the therapeutic effects, new insights, and upcoming perspectives of Que.

The Effects and Mechanism of Quercetin Dietary Supplementation in Streptozotocin-Induced Hyperglycemic Arbor Acre Broilers

Quercetin, a flavonoid found in fruits and vegetables, is widely distributed as a secondary metabolite in the plant kingdom. Oxidative stress plays a role in the pathogenesis of diabetes mellitus (DM). The present study investigated the effects of quercetin dietary supplementation on streptozotocin- (STZ-) induced hyperglycemic Arbor Acre (AA) broilers by determining the levels of fasting blood glucose (FBG), fasting insulin (FINS), biochemical indicators, oxidative stress markers, inflammatory cytokines content, antioxidant enzymes activities in tissues, and mRNA expression of genes relating to the insulin signaling pathway. Three hundred one-day-old healthy AA broilers were randomly assigned into 5 treatments; A, control healthy broilers; B, STZ-induced broilers; C, STZ-induced broiler dietary supplemented with 0.02% quercetin; D, STZ-induced broiler dietary supplemented with 0.04% quercetin; and E, STZ-induced broiler dietary supplemented with 0.06% quercetin. The results showed that quercetin supplementation relieved the side effects of STZ-induced oxidative stress by changing activities of antioxidant enzymes, decreasing malondialdehyde (MDA) and nitric oxide (NO) levels, activating expression of genes relating to PI3K/PKB signaling pathway that modulate glucose metabolism and reduce oxidative damage, thereby decreasing FBG and increasing FINS levels. These findings suggest that quercetin exhibits a protective effect in STZ-induced hyperglycemic AA broilers via decreasing oxidative stress.

Flavonoids for preserving pancreatic beta cell survival and function: A mechanistic review

Although the currently available antidiabetic medications are effective in managing hyperglycemia, vascular complications are common in diabetic patients. Cohort studies have shown preserved beta cell function has a protective role against the development of diabetic complications. Accordingly, beta cell mass and function are important pharmacological targets in the field of diabetes. Growing number of evidence supports the efficacy of flavonoids (e.g., quercetin, kaempferol, luteolin, and epicatechin) for prevention and attenuation of diabetes consequences. The focus of this paper is to give an overview regarding the effects of flavonoids on pancreatic beta cells. Experiments on insulin-releasing cell lines, isolated pancreatic islets, and diabetic animal models have shown that flavonoids strengthen the survival processes and insulin secretory capacity of beta cells. The proposed mechanisms by which flavonoids preserve beta cells survival (against cytokines, glucotoxicity, and lipotoxicity) include inhibition of NF-κB signaling, activation of PI3K/Akt pathway, inhibition of nitric oxide generation, and decrease of reactive oxygen species levels. Improving mitochondrial bioenergetic function and stimulating pathways of insulin secretion (e.g., PLC/PKC and/or cAMP/PKA signaling) are mechanisms by which flavonoids improve the secretory capacity of beta cells. These beneficial effects of flavonoids are of great importance because may protect beta cells of diabetic patients before dramatic dysfunction and degeneration.

Effects of icariside II on brain tissue oxidative stress and Nrf2/HO-1 expression in rats with cerebral ischemia-reperfusion injury1

PURPOSE

To investigate the effects of icariside II on brain tissue oxidative stress and Nrf2/HO-1 expression in rats with cerebral ischemia-reperfusion injury (CIRI).

METHODS

One hundred SD rats were randomly divided into sham-operated, model, and 5, 10 and 20 mg/kg icariside II groups, 20 rats in each group. The middle cerebral artery occlusion model (ischemia for 2 h followed by reperfusion for 24 h) was established in the later 4 groups. In later 3 groups, at reperfusion beginning, the rats were intragastrically administrated with 5, 10 and 20 mg/kg icariside II, respectively. After 24 h of reperfusion, the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue oxidative stress indexes and Nrf2 and HO-1 protein expressions were determined.

RESULTS

Compared with model group, in 20 mg/kg icariside II group the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue ROS content and MDA level were significantly decreased (P<0.05), and the brain tissue SOD, GSH-Px and catalase levels and Nrf2 and HO-1 protein levels were significantly increased (P<0.05).

CONCLUSION

Icariside II can alleviate the CIRI in rats through reducing brain tissue oxidative stress and improving Nrf2/HO-1 expression.

Study of the Antidiabetic Activity of Punica granatum L. Fruits Aqueous Extract on the Alloxan-Diabetic Wistar Rats

Pancreatic β-cells dysfunction and impairment of insulin action usually leads to hyperglycemia. Punica granatum L. is a well-known traditional herbal remedy in Iran due to its positive effects on ameliorating blood glucose homeostasis. In this study, Alloxan-diabetic male Wistar rats were administrated with pomegranate fruits aqueous extract (PE) in different doses of 100, 200, and 350 mg/kg bw (PE+Da, PE+Db and PE+Dc, respectively), and the effects of PE polyphenols content on glucose metabolism in treated groups were examined using oral glucose tolerance test (OGTT), short-term and long-term PE consumption periods models followed by evaluation of plasma insulin, free fatty acids, and triglycerides levels and tissues contents of glycogen and triglycerides; compared with diabetic control (DC) and healthy control (NC) groups. By using Real-time PCR, the possibility of modulations of the Insulin receptor substrate 1 (IRS-1), Protein kinase B (Akt), Glucose transporter 2 and 4 (Glut-2, 4) mRNAs expression levels in PE treated rats were investigated. The obtained data showed noticeable reduction in fasting blood glucose (FBG) by 28.1% and 67.9% in short-term and long-term treatment models, respectively, in PE + Dc group. Also, there existed marked increase in the mRNAs expression levels of IRS-1, Akt, Glut-2, and Glut-4, which results in improvement of glucose uptake and promotes its storage. Taking together, it is suggested that PE administration contributes to the modulation of both hyperglycemia and hyperlipidemia in Alloxan-diabetic Wistar rats.

Differential Impact of Flavonoids on Redox Modulation, Bioenergetics, and Cell Signaling in Normal and Tumor Cells: A Comprehensive Review

SIGNIFICANCE

Flavonoids can interact with multiple molecular targets to elicit their cellular effects, leading to changes in signal transduction, gene expression, and/or metabolism, which can, subsequently, affect the entire cell and organism. Immortalized cell lines, derived from tumors, are routinely employed as a surrogate for mechanistic studies, with the results extrapolated to tissues in vivo. Recent Advances: We review the activities of selected flavonoids on cultured tumor cells derived from various tissues in comparison to corresponding primary cells or tissues in vivo, mainly using quercetin and flavanols (epicatechin and (-)-epigallocatechin gallate) as exemplars. Several studies have indicated that flavonoids could retard cancer progression in vivo in animal models as well as in tumor cell models.

CRITICAL ISSUES

Extrapolation from in vitro and animal models to humans is not straightforward given both the extensive conjugation and complex microbiota-dependent metabolism of flavonoids after consumption, as well as the heterogeneous metabolism of different tumors.

FUTURE DIRECTIONS

Comparison of data from studies on primary cells or in vivo are essential not only to validate results obtained from cultured cell models, but also to highlight whether any differences may be further exploited in the clinical setting for chemoprevention. Tumor cell models can provide a useful mechanistic tool to study the effects of flavonoids, provided that the limitations of each model are understood and taken into account in interpretation of the data.

Effects of Quercetin on Lipid and Protein Damage in the Liver of Streptozotocin-Induced Experimental Diabetic Rats

Quercetin (QR) is part of a subclass of flavonoids called flavonols. We aimed to investigate the effect of QR on malondialdehyde (MDA), advanced oxidation protein products (AOPPs), and glutathione peroxidase (GSH-Px) activity in the liver of diabetic rats. We compared four groups of male adult Wistar albino rats: a control group, an untreated diabetic group, diabetic groups treated with QR, and QR group. Diabetes was induced by a single injection of streptozotocin (STZ) (50 mg/kg). Animals were kept in standard condition. On the 31st day of the study, the liver tissue was removed for biochemical parameters and histopathological evaluations. In an untreated diabetic group, liver MDA and AOPP levels were significantly higher than all groups. QR treatment significantly decreased the increased MDA, AOPP levels, and increased the decreased GSH-Px enzyme activity in liver tissues. The QR-treated rats in the diabetic group showed an improved histological appearance. Lesser vesicular vacuolization and fibrotic areas were observed in the QR-treated diabetic group than in the diabetic group. The STZ-induced liver injury is associated with oxidative stress, and coadministration of QR may reduce this damage effectively in a rat model. Our results are also supported by morphological improvement in liver tissue. Therefore, we think QR may be effective in treating hyperglycemia and oxidative damage in diabetes.

Black Seed Thymoquinone Improved Insulin Secretion, Hepatic Glycogen Storage, and Oxidative Stress in Streptozotocin-Induced Diabetic Male Wistar Rats

Diabetes mellitus is one of the metabolic diseases having several complications. Nigella sativa oil (NSO) might have beneficial effects in the treatment of diabetic complications. Thirty-two mature male Wistar rats were equally divided into four experimental groups: control, control NSO 2 mL/kg, streptozotocin- (STZ-) induced diabetic, and diabetic (STZ-induced) treated with oral NSO 2 mg/kg for 30 days. Fasting blood glucose (FBG), insulin, and lipid profile levels were determined. Pancreatic and hepatic tissues were used for catalase and GSH. Histopathology, hepatic glycogen contents, insulin immunohistochemistry, and pancreatic islet morphometry were performed. NSO 2 mL/kg was noticed to decrease (P < 0.05) FBG and increase (P < 0.05) insulin levels in diabetic rats than in diabetic nontreated animals. Lipid profile showed significant (P < 0.5) improvement in diabetic rats that received NSO 2 mL/kg than in the diabetic group. Both pancreatic and hepatic catalase and GSH activities revealed a significant (P < 0.05) increment in the diabetic group treated with NSO than in the diabetic animals. NSO improved the histopathological picture and hepatic glycogen contents of the diabetic group as well as increased (P < 0.05) insulin immunoreactive parts % and mean pancreatic islet diameter. NSO exerts ameliorative and therapeutic effects on the STZ-induced diabetic male Wistar rats.

Anti-ulcer and anti-Helicobacter pylori potentials of the ethyl acetate fraction of Physalis alkekengi L. var. franchetii (Solanaceae) in rodent

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis alkekengi L. var. franchetii (Solanaceae) has been widely used in Chinese folk medicine due to its wide distribution throughout the country, for the treatment of a wide range of diseases including heat and cold, sore throat, fever, fungal infection, inflammation, toothache, rheumatism, burn, analgesic, ulcer and urinary diseases. However, the effect of P. alkekengi var. franchetii on ulcer and Helicobacter pylori infection has not been reported to date.

AIM OF THE STUDY

This study was designed to investigate the anti-inflammatory, anti-ulcer, anti-Helicobacter pylori and analgesic properties of ethyl acetate fraction of the crude aqueous methanolic extract from the aerial parts of the plant P. alkekengi L. var. franchetii in rodents.

MATERIALS AND METHODS

Acute toxicity of the crude extract of P. alkekengi L. var. franchetii (PAF) was evaluated in rats. The petroleum ether fraction (PEF), butanol fraction (BF), ethyl acetate fraction (EAF) and aqueous fraction (AF) of crude aqueous methanolic extract from PAF were screened for anti-inflammatory and anti-ulcer potential at doses of 100, 250 and 500mg/kg (p.o.), using carrageenin-induced hind paw edema and ethanol-induced gastric lesions test in rats. In vitro anti-Helicobacter pylori activity of EAF was assayed subsequently. In addition, three doses of EAF were evaluated for analgesic activity using hot plate and writhing tests, respectively. Finally, we performed a phytochemical analysis of EAF.

RESULTS

Four fractions of crude extract from PAF significantly reduced the paw volume in carrageenin-induced hind paw edema model at different doses (100, 250 and 500mg/kg, p.o.). The fraction EAF at a dose of 500mg/kg exhibited the highest (75.92%) (0.150 ± 0.045***, ***p < 0.001) anti-inflammatory potential, which is similar to indomethacin (***P < 0.001)（0.120 ± 0.014***, 80.74% inhibition of inflammation） at 5mg/kg. Pretreatment with EAF (500mg/kg, p.o.) significantly reduced the intensity of gastric mucosal damage and showed higher gastroprotective activity (90.6%) when compared to the standard drug famotidine (84.6%). In addition, EAF fraction also showed a moderate (P < 0.05) anti-Helicobacter pylori activity with a minimal inhibition concentration (MIC) of 500μg/ml. Furthermore, pain sensation was effectively inhibited at 500mg/kg, p.o. of EAF as manifested by an increase (p < 0.001) of latency time in hot plate from 30 to 90min and a decrease (p < 0.001) in count of writhing induced by acetic acid. By HPLC, we determined some steroid, terpenoid and flavonoids (four compounds): kaempferol, quercetin, Blumenol A and physalindicanols A, which were isolated from the ethyl acetate fraction and identified using ¹H NMR and ¹³C NMR spectra analysis.

CONCLUSION

This study demonstrated the anti-inflammatory, anti-ulcer, anti-Helicobacter pylori and analgesic properties of EAF of the crude extract from PAF thus justifying its traditional usage.

Anti-hypoglycemic and hepatocyte-protective effects of hyperoside from Zanthoxylum bungeanum leaves in mice with high-carbohydrate/high-fat diet and alloxan-induced diabetes

The development of diabetes mellitus (DM) is accompanied by hyperglycemia-induced oxidative stress. Hyperoside is a major bioactive component in Zanthoxylum bungeanum leaves (HZL) and is a natural antioxidant. However, the effects of HZL on DM and its mechanisms of action remain undefined. The present study evaluated the anti-hypoglycemic and hepatocyte-protective effects of HZL in mice with diabetes induced by a high-carbohydrate/high-fat diet (HFD) and alloxan. We also aimed to eludicate the underlying mechanisms. Our resutls demonstrated that the administration of HZL significantly reduced body weight gain, serum glucose levels and insulin levels in diabetic mice compared with the vehicle-treated mice. In addition, the levels of dyslipidemia markers including total cholesterol, triglyceride and low-density lipoprotein cholesterol in the HFD-treated mice were markedly decreased. Further experiments using hepatocytes from mice revealed that HZL significantly attenuated liver injury associated with DM compared with vehicle treatment, as evidenced by lower levels of alanine aminotransferase and aspartate aminotransferase in serum and by lower levels of lipid peroxidation, nitric oxide content and inducible nitric oxide synthase activity in liver tissues. Nuclear factor-κB (NF-κB) and mitogen-associated protein kinase (MAPK) signaling pathways were investigated to elucidate the molecular mechanisms responsible for the protective effects of HZL against diabetic liver injury. The results indicated that HZL inhibited the phosphorylation of p65/NF-κB, MAPK (including p38, JNK and ERK1/2) and activating transcription factor 3 protein expression, with an additional suppression of Bax, cytochrome c, caspase-9 and caspase-3 in the liver tissues of diabetic mice. Taken together, our findings suggest that HZL, which was effective in inhibiting oxidative stress-related pathways may be beneficial for use in the treatment of DM.

The effect of hesperidin and quercetin on oxidative stress, NF-κB and SIRT1 levels in a STZ-induced experimental diabetes model

OBJECTIVE

The aim of this study is to investigate the roles of SIRT1 and NF-κB in the pathogenesis of diabetes mellitus in rats with STZ-induced diabetes and determine the effects of hesperidin and quercetin on oxidative stress and on the levels of SIRT1 and NF-κB.

MATERIALS AND METHODS

The experimental animals were divided into four groups, each group comprising ten rats designated as follows: group 1 served as control rats (C); group 2 served as diabetic rats (DM); group 3 served as diabetic rats administered hesperidin (DM+HSP) (100mg/kg b.w.) in aqueous suspension orally for 15 days; and group 4 served as diabetic rats administered quercetin (DM+Q) (100mg/kg b.w.) in aqueous suspension orally for 15 days.

RESULTS

In diabetic group, liver and kidney SIRT1, SOD and CAT activities were significantly lower than control group (p<0.05). Hesperidin and quercetin caused significant increase in the SIRT1, SOD and CAT activities of both DM+HP and DM+Q groups kidney tissues compared to DM group (p<0.05). Liver SOD activies were not found to differ significantly between DM, DM+Q and DM+HP groups (p>0.05). In DM+HP group, liver CAT activities were significantly higher than DM (p<0.05), but there was no significant difference in liver CAT activities between DM and DM+Q (p>0.05). In diabetic group, liver and kidney NF-κB and MDA levels were increased compared to control group (p<0.05), and groups of DM+HP and DM+Q had lower NF-κB and MDA levels than diabetic group (p<0.05).

CONCLUSION

As a conclusion, based on the results we obtained from this study and the literature data discussed above, we determined in STZ-induced diabetic rats that, increased glucose levels and liver and kidney damage markers decreased significantly after administration of hesperedin and quercetin, and that oxidative stress and NF-κB levels increased while SIRT1 levels decreased in the diabetic group.

Benzbromarone, Quercetin, and Folic Acid Inhibit Amylin Aggregation

Human Amylin, or islet amyloid polypeptide (hIAPP), is a small hormone secreted by pancreatic β-cells that forms aggregates under insulin deficiency metabolic conditions, and it constitutes a pathological hallmark of type II diabetes mellitus. In type II diabetes patients, amylin is abnormally increased, self-assembled into amyloid aggregates, and ultimately contributes to the apoptotic death of β-cells by mechanisms that are not completely understood. We have screened a library of approved drugs in order to identify inhibitors of amylin aggregation that could be used as tools to investigate the role of amylin aggregation in type II diabetes or as therapeutics in order to reduce β-cell damage. Interestingly, three of the compounds analyzed-benzbromarone, quercetin, and folic acid-are able to slow down amylin fiber formation according to Thioflavin T binding, turbidimetry, and Transmission Electron Microscopy assays. In addition to the in vitro assays, we have tested the effect of these compounds in an amyloid toxicity cell culture model and we have found that one of them, quercetin, has the ability to partly protect cultured pancreatic insulinoma cells from the cytotoxic effect of amylin. Our data suggests that quercetin can contribute to reduce oxidative damage in pancreatic insulinoma β cells by modulating the aggregation propensity of amylin.

Quercetin mitigates fenitrothion-induced testicular toxicity in rats

Fenitrothion (FNT) is a widely used organophosphorus pesticide in agriculture. Quercetin (QR), a plant-derived flavonoid, has a free radical scavenging property. This study investigated the protective effect of QR on FNT-induced testicular toxicity in rats. Twenty-four male rats were divided into four groups. Group I (control) received normal saline. Group II was administered QR at the dose of 50 mg kg(-1) b.wt. Group III was orally administered FNT (20 mg kg(-1) b.wt). Group IV was gavaged FNT and QR together at the same doses. All administrations were performed daily by gavage and maintained for 70 days. Sperm parameters and histopathological changes in testes were investigated. Serum testosterone and luteinising hormone were estimated using radioimmunoassay kits. In testes, expressions of steroidogenic genes (3β-hydroxysteroid dehydrogenase type 6, 17 β-hydroxysteroid dehydrogenase type 3 and steroidogenic factor-1) and oxidative stress genes (catalase and superoxide dismutase) were determined using real-time PCR. FNT administration caused significant decreases in sperm count, motility and hormonal levels, a significant increase in abnormal sperm morphology and a significant down-regulation of steroidogenic and antioxidant genes in the testis. However, QR administration ameliorated FNT-induced toxic effects. Our results concluded that QR effectively mitigated testicular damage induced by FNT in rats.

Effect of genistein, a natural soy isoflavone, on pancreatic β-cells of streptozotocin-induced diabetic rats: Histological and immunohistochemical study

Diabetes mellitus is one of the oldest disorders that is rapidly emerging as a global health problem. Soy genistein is a legume that has numerous health benefits. This work aimed to study the effect of different doses of genistein on histological, immunohistochemical and morphometrical changes in β-cells of streptozotocin (STZ)-induced diabetic rats and to correlate these effects with plasma glucose and insulin levels. Fifty adult male rats were divided into five equal groups. Group I served as a control. Group II received genistein. Group III comprised STZ-induced diabetic rats. Group IV diabetic animals treated with low dosage genistein. Group V diabetic animals treated with high dosage genistein. Genistein was given for 4 weeks after STZ injection. Rats were sacrificed and pancreatic specimens were taken for light and electron microscopic examination. Blood samples were collected for detection of serum glucose and insulin levels. After diabetic induction, the islets appeared shrunken with cytoplasmic vacuolation of their cells and negative insulin immunoreaction. Ultrastructurally, β-cells showed darkly stained nuclei with marked loss of granules. Morphometrically, significant loss of β-cells was detected. The serum insulin level was decreased with elevation in the serum glucose. High-dose but not low-dose genistein improved the morphology of islets with increased insulin immunoreaction. Genistein also significantly decreased β-cells loss and improved glucose and insulin levels. In conclusion, genistein has a protective effect on pancreatic β-cells damage, possesses the ability to regenerate β-cells and improves serum levels of insulin and glucose in STZ-induced diabetic rats in a dosage-dependent manner.

Quercetin induces insulin secretion by direct activation of L-type calcium channels in pancreatic beta cells

BACKGROUND AND PURPOSE

Quercetin is a natural polyphenolic flavonoid that displays anti-diabetic properties in vivo. Its mechanism of action on insulin-secreting beta cells is poorly documented. In this work, we have analysed the effects of quercetin both on insulin secretion and on the intracellular calcium concentration ([Ca(2+)]i) in beta cells, in the absence of any co-stimulating factor.

EXPERIMENTAL APPROACH

Experiments were performed on both INS-1 cell line and rat isolated pancreatic islets. Insulin release was quantified by the homogeneous time-resolved fluorescence method. Variations in [Ca(2+)]i were measured using the ratiometric fluorescent Ca(2+) indicator Fura-2. Ca(2+) channel currents were recorded with the whole-cell patch-clamp technique.

KEY RESULTS

Quercetin concentration-dependently increased insulin secretion and elevated [Ca(2+)]i. These effects were not modified by the SERCA inhibitor thapsigargin (1 μmol·L(-1)), but were nearly abolished by the L-type Ca(2+) channel antagonist nifedipine (1 μmol·L(-1)). Similar to the L-type Ca(2+) channel agonist Bay K 8644, quercetin enhanced the L-type Ca(2+) current by shifting its voltage-dependent activation towards negative potentials, leading to the increase in [Ca(2+)]i and insulin secretion. The effects of quercetin were not inhibited in the presence of a maximally active concentration of Bay K 8644 (1 μmol·L(-1)), with the two drugs having cumulative effects on [Ca(2+)]i.

CONCLUSIONS AND IMPLICATIONS

Taken together, our results show that quercetin stimulates insulin secretion by increasing Ca(2+) influx through an interaction with L-type Ca(2+) channels at a site different from that of Bay K 8644. These data contribute to a better understanding of quercetin's mechanism of action on insulin secretion.

Hepatoprotective and Pancreatoprotective Properties of the Ethanolic Extract of Nigerian Propolis

Objective:

Increased oxidative stress is associated with the progression of diabetic mellitus. In the present study, we investigated the effects of the ethanolic extract of Nigerian propolis (N. propolis) on markers of oxidative stress, histology of the liver and pancreas and glycaemia in alloxan-induced diabetic rats.

Materials and Methods:

Alloxan-induced hyperglycemic Wistar rats were treated with either metformin (150 mg/kg/d) or N. propolis (200 mg/kg/d and 300 mg/kg/d) for 28 days. At the end of the treatment period, the rats were sacrificed; blood was collected for biochemical analysis while their pancreases and liver were excised and processed for histological studies.

Results:

Serum oxidative stress markers and blood glucose concentration were compared between the treated and control rats. In contrast to the non-treated diabetic rats, blood glucose concentration were not significantly different between treated rats and control (P < 0.05) at 28 days of treatment with N. propolis and metformin. Serum malondialdehyde levels was reduced while superoxide dismutase levels were elevated in the N. propolis group; these levels were converse in the diabetic group, these differences are statistically significant (P<0.05) when compared with the control. Histologically, there was improvement in the treated group compared to the untreated group.

Conclusion:

These findings suggest that the N. propolis confers protection against hyperglycemia-induced oxidative stress in both liver and pancreas of adult Wistar rats.

Effect of single oral dose of proanthocyanidin on postprandial hyperglycemia in healthy rats: A comparative study with sitagliptin

Background:

Many of flavonoid rich natural products found to have a significant influence on postprandial hyperglycemia, a major risk factor for diabetic complications. Enhancement of insulinotropic gut hormones by inhibition of dipeptidyl peptidase-IV (DPP-IV) are among the newest strategies for treatments of Type 2 diabetes which thought to be the underlying action through which flavonoid can reduce postprandial hyperglycemia.

Aim:

This study aim was designed to investigate the potential role of standardized grape seed proanthocyanidin in controlling postprandial hyperglycemia by enhancing the regulatory incretin effect of gut hormones in response to oral and intraperitoneal (I.P) glucose load in healthy rats.

Materials and Methods:

Five groups of animals each of six rats were used in this study, which was conducted in March 2013. Groups (II and V) treated with single oral dose of proanthocyanidin (50 mg/kg), Group III received single oral dose of sitagliptin (40 mg/kg) and Groups (I and IV) treated with vehicle serve as control groups. All treatments were given 30 min before oral or I.P glucose load. Blood glucose was estimated over 2 h duration at (0, 30, 60, 90, and 120) min from glucose load.

Result:

Both proanthocyanidin and sitagliptin significantly improve hyperglycemia induced by oral glucose load relative to control. While non-significant changes were achieved by proanthocyanidin after I.P glucose challenge compared to untreated control group.

Conclusion:

The result of this study indicated that proanthocyanidin may possess an enhancement of incretin effect of gut peptides, which could be responsible for some of its action on glucose homeostasis. This finding may provide an opportunity for further pharmacological studies using more specific models to clarify the possible action of proanthocyanidin as a natural DPP-IV inhibitor.

Otostegia persica (Lamiaceae): A review on its ethnopharmacology, phytochemistry, and pharmacology

OBJECTIVE

The current study summarizes the updated information concerning the ethnopharmacology, Phytochemistry, and pharmacology of Otostegia persica Boiss. (Lamiaceae), an endemic medicinal plant in south and southeast of Iran.

MATERIALS AND METHODS

Information was collected through bibliographic investigation from scientific journals, books, theses, reports, and electronic search (databases SCOPUS, Google Scholar, Web of Science, and Science Direct). Moreover, documentation from unpublished resources and ethnobotanical surveys has been used. The present review covers the literature available from 2003 to 2013.

RESULTS

In traditional systems of medicine, this plant is reputed for treating diabetes, arthritis, gastric discomfort, headache, rheumatism, sedative activities, regulating blood pressure, and hyperlipidemia. Phytochemical screening of active components and mineral element evaluation of this species have been reported. Several types of diterpenoids and flavonols including morin, kaempferol, and quercetin are identified from the plant. Most of the pharmacological activity of this plant resides in its flavonoid fraction which causes antimicrobial and antioxidant activities. Various pharmacological studies on O. persica show antimicrobial, antioxidant, anti-inflammatory, anti-diabetic, anti-aphid, and hepatoprotective activities.

CONCLUSION

Being an endemic plant of Iran, this species is an important medicinal herb which can be used for various purposes. This review might be helpful for scientists and researchers to find new chemical entities responsible for its claimed traditional uses and discover new lead compounds for diseases mentioned.

Antimicrobial activities of the methanol extract and compounds from Artocarpus communis (Moraceae)

Background

Artocarpus communis is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antimicrobial activities of the methanol extract (ACB) and compounds isolated from the bark of this plant, namely peruvianursenyl acetate C (1), α-amyrenol or viminalol (2), artonin E (4) and 2-[(3,5-dihydroxy)-(Z)-4-(3-methylbut-1-enyl)phenyl]benzofuran-6-ol (5).

Methods

The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species.

Results

The MIC results indicated that ACB as well as compounds 4 and 5 were able to prevent the growth of all tested microbial species. All other compounds showed selective activities. The lowest MIC value of 64 μg/ml for the crude extract was recorded on Staphylococcus aureus ATCC 25922 and Escherichia coli ATCC 8739. The corresponding value of 32 μg/ml was recorded with compounds 4 and 5 on Pseudomonas aeruginosa PA01 and compound 5 on E. coli ATCC 8739, their inhibition effect on P. aeruginosa PA01 being more than that of chloramphenicol used as reference antibiotic.

Conclusion

The overall results of this study provided supportive data for the use of A. communis as well as some of its constituents for the treatment of infections associated with the studied microorganisms.

Quercetin attenuates fasting and postprandial hyperglycemia in animal models of diabetes mellitus

The objective of this study was to investigate the hypoglycemic effects of quercetin (QE) in animal models of diabetes mellitus (DM). A starch solution (1 g/kg) with and without QE (100 mg/kg) or acarbose (40 mg/kg) was orally administered to streptozotocin (STZ)-induced diabetic rats after an overnight fast. Postprandial plasma glucose levels were measured and incremental areas under the response curve were calculated. To study the effects of chronic feeding of QE, five-week-old db/db mice were fed an AIN-93G diet, a diet containing QE at 0.08%, or a diet containing acarbose at 0.03% for 7 weeks after 1 week of adaptation. Plasma glucose and insulin, blood glycated hemoglobin, and maltase activity of the small intestine were measured. Oral administration of QE (100 mg/kg) or acarbose (40 mg/kg) to STZ-treated rats significantly decreased incremental plasma glucose levels 30-180 min after a single oral dose of starch and the area under the postprandial glucose response, compared with the control group. QE (0.08% of diet) or acarbose (0.03% of diet) offered to db/db mice significantly reduced both plasma glucose and blood glycated hemoglobin compared to controls without significant influence on plasma insulin. Small intestine maltase activities were significantly reduced by consumption of QE or acarbose. Thus, QE could be effective in controlling fasting and postprandial blood glucose levels in animal models of DM.