Evaluation of antiulcer potential of Mimusops hexandra in experimental gastro duodenal ulcers.

The study was aimed to investigate antiulcer effects of acetone extract and its different fractions Mimusops hexandra against experimental gastro-duodenal ulcers. 80% acetone extract of stem bark of Mimusops hexandra (Extract A, p.o.) and its different fractions namely diethyl ether (Extract A1, p.o.), ethyl acetate (Extract A2, p.o.) and aqueous (Extract A3, p.o.) were tested for the presence of preliminary phytoconstituents and were screened for their antiulcer potential in experimental animals using ethanol-HCl and aspirin-induced gastric damage at the dose of 500 mg kg-1p.o. Extract A2 being the most active fraction amongst all the fractions tested was also studied at different doses to find its ED50. Further, to establish the mechanism of action, Extract A2 was also tested for its effects in acetic acid-induced gastric ulcer models and cysteamine-induced duodenal ulcer. The effect was compared with cimetidine. Flavonoids (quercetin), procyanidins, saponins and triterpenoids were found to be present in bark. Oral administration of Extract A2 inhibited formation of gastric lesions induced by aspirin in a dose dependent manner. Elevated level of lipid peroxidation due to ethanol-HCl and aspirin induced gastric damage was significantly (p<0.05) reduced by the treatment with Extract A2. Further, Extract A2 at the dose of 100 mg kg-1 (p.o.) reduced extent of acetic acid induced gastric ulcer in experimental animals. Moreover, protection afforded by Extract A2 against cysteamine-induced duodenal lesions was evident from dose dependent decrease in ulcer index (p<0.05), score for intensity (p<0.05) and total lesion area (p<0.05), when compared with the control group. The antiulcer activity shown by Extract A2 in experimental gastro-duodenal ulcer could be attributed to decrease in gastric acid secretory activity along with strengthening of mucosal defensive mechanisms.

Involvement of the PI3K/AKT pathway in the hypoglycemic effects of saponins from Helicteres isora.

AIM OF THE STUDY: Saponins from Helicteres isora have previously been shown to exert antidiabetic effects. The present study explored the underlying mechanisms in C2C12 skeletal muscle cells. MATERIALS AND METHODS: C2C12 cells were incubated with saponins and sapogenin followed by Western blotting and immunofluorescence analysis. RESULTS: Western blotting revealed that incubation with saponins (100 microg/ml) and sapogenin (100 microg/ml) induced the phosphorylation of the phosphatidylinositol-3-kinase (PI3K) as well as of the downstream targets protein kinase B/Akt (at Ser473) and glycogen synthase kinase GSK-3 alpha/beta (at Ser21/9) in a time-dependent manner. In contrast, no phosphorylation of the AMP-sensitive kinase AMPK (at Thr172) was observed. Within 48 h saponins/sapogenin treatment further increased the protein abundance of the insulin-sensitive glucose transporter Glut4. Confocal microscopy confirmed that saponins/sapogenin treatment stimulated Akt phosphorylation and revealed that the treatment was followed by translocation of Glut4 into the cell membrane of C2C12 muscle cells. CONCLUSIONS: Saponins and sapogenin activate the PI3K/Akt pathway thus leading to phosphorylation and inactivation of GSK-3 alpha/beta with subsequent stimulation of glycogen synthesis as well as increase of Glut4-dependent glucose transport across the cell membrane.

Effect of saponins from Helicteres isora on lipid and glucose metabolism regulating genes expression.

ETHNOPHARMACOLOGICAL RELEVANCE: We characterized saponins as active constituents from traditionally used antidiabetic plant Helicteres isora. AIM OF THE STUDY: To evaluate the changes in the gene expression of the glucose and lipid metabolism regulating genes in C57BL/KsJ-db/db mice. MATERIALS AND METHODS: C57BL/KsJ-db/db mice were divided into four different groups; one diabetic control, the mice in other three groups were treated with methanol extract (100 mg/kg), saponins (100 mg/kg) and pioglitazone (30 mg/kg) for 14 days. After completion of the treatment period biochemical parameters and the expression levels of adipsin, adiponectin, glucose transporter 4 (Glut4), peroxisome proliferator activated receptor gamma (PPARgamma), fatty acid binding protein 4 (FABP4), lipoprotein lipase (LPL) in adipose tissue and for liver RNA samples glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), glucose transporter 2 (Glut2) and acyl-co-enzyme A oxidase (ACOX) were determined by quantitative real time PCR and angiopoeitin like 3 (ANGPTL3), angiopoeitin like 4 (ANGPTL4) and peroxisome proliferator activated receptor alpha (PPARalpha) by semiquantitative reverse transcription PCR. RESULTS: Treatment caused a significant reduction in the serum lipid and glucose levels and increased the expression of adipsin, PPARgamma and Glut4 while reduced expression of FABP4 and G6Pase, whereas there was no effect on the expression levels of adiponectin, LPL, PEPCK, ACOX, Glut2, ANGPTL3, ANGPTL4 and PPARalpha. CONCLUSIONS: Saponins are beneficial for improving hyperlipidemia and hyperglycemia by increasing the gene expression of adipsin, Glut4 and PPARgamma and reducing the gene expression of the enzyme G6Pase and FABP4 in C57BL/KsJ-db/db mice.

Experimental evidence for the cardioprotective effects of red wine.

Both epidemiological and experimental studies have revealed that intake of wine, particularly red wine, in moderation protects cardiovascular health; however, the experimental basis for such an action is not fully understood. Because all types of red wine contain varying amounts of alcohol and antioxidants, it is likely that the cardioprotective effect of red wine is due to both these constituents. In view of its direct action on the vascular smooth muscle cells, alcohol may produce coronary vasodilation in addition to attenuating oxidative stress by its action on the central nervous system. The antioxidant components of red wine may provide cardioprotection by their ability to reduce oxidative stress in the heart under different pathological conditions. Mild-to-moderate red wine consumption improves cardiac function in the ischemic myocardium through the protection of endothelial function, the expression of several cardioprotective oxidative stress-inducible proteins, as well as the activation of adenosine receptors and nitrous oxide synthase mechanisms.

Angiogenesis--a new target for future therapy.

Development of blood vessels from in situ differentiating endothelial cells (EC) is called vasculogenesis, whereas sprouting of new blood vessels from the pre-existing ones is termed angiogenesis or neovascularisation. Angiogenesis, the growth of new blood vessels, is essential during tissue repair, foetal development, and female reproductive cycle. In contrast, uncontrolled angiogenesis promotes tumor and retinopathies, while inadequate angiogenesis can lead to coronary artery disease. A balance between pro-angiogenic and anti-angiogenic growth factors and cytokines tightly controls angiogenesis. With the identification of several proangiogenic molecules such as the vascular endothelial cell growth factor (VEGF), the fibroblast growth factors (FGFs), and the angiopoietins, and the recent description of specific inhibitors of angiogenesis such as platelet factor-4, angiostatin, endostatin, and vasostatin, it is recognized that therapeutic interference with vasculature formation offers a tool for clinical applications in various pathologies. Inhibition of angiogenesis can prevent diseases such as cancer, diabetic nephropathy, arthritis, psoriasis, whereas stimulation of angiogenesis is beneficial in the treatment of coronary artery disease (CAD), cardiac failure, tissue injury, etc. One of the most specific and critical regulators of angiogenesis is vascular endothelial growth factor (VEGF), which regulates endothelial proliferation, permeability, and survival. Substantial evidence also implicates VEGF as an angiogenic mediator in tumors and intraocular neovascular syndromes, and numerous clinical trials are presently testing the hypothesis that inhibition of VEGF may have therapeutic value.

A novel use of methylene blue as a pharmacological tool.

INTRODUCTION: A new use of methylene blue as an ulcerogenic agent and the mechanisms involved were identified with an objective to exploit methylene blue as a pharmacological tool to study investigational antiulcer agents. METHODS: Ulcerogenic potential was assessed using electron microscopy and measurement of an ulcer index after administering methylene blue (5-125 mg kg(-1), p.o.) or absolute ethanol (99%v/v, 2 ml, p.o.) to fasted rats. Estimation of thiobarbituric acid reactive substances, superoxide dismutase, reduced glutathione and catalase was used to assess oxidative stress. H(+)/K(+) ATPase activity, gastric mucosal blood flow and gastric acid secretion were measured to study the mechanism of methylene induced gastric ulcer. RESULTS: Methylene blue (100 mg kg(-1), p.o.) produced marked ulceration of the gastric mucosa due to increased levels of thiobarbituric acid reactive substances, activities of the H(+)/K(+) ATPase and superoxide dismutase, and decreased blood flow to the gastric mucosa, activity of catalase combined with reduced glutathione levels. DISCUSSION: It may be concluded that methylene blue activates the H(+)/K(+) ATPase to increase gastric acid secretion and reduces blood supply to gastric mucosa to produce oxidative stress that subsequently causes ulceration of gastric mucosa. Methylene blue can be used as an ulcerogenic agent to study mechanisms of investigational antiulcer agents.

Effects of chronic treatment with cromakalim and glibenclamide in alloxan-induced diabetic rats.

We have studied the effects of chronic treatment with cromakalim (75 ug kg(-1) per day) and glibenclamide (20 mg kg(-1) per day) in alloxan-induced diabetic rats. Injection of alloxan (60 mg kg(-1)/i.v., single dose) produced a significant increase in the blood pressure, bradycardia, hyperglycemia, hypoinsulinemia, hyperlipidemia, hypothyroidism and depression in left ventricular developed pressure (LVDP). While glibenclamide significantly prevented alloxan-induced hyperglycemia and hypoinsulinaemia, it failed to alter hypertension, bradycardia, hypertriglyceridaemia and hypercholesterolemia. Treatment with cromakalim-prevented hypertension and bradycardia, but not the hyperglycemia or hypoinsulinaemia. Co-administration of cromakalim with glibenclamide antagonized the effect of glibenclamide on these parameters. Cromakalim treatment also prevented alloxan-induced hypercholesterolemia and hypertriglyceridaemia. It also produced a significant increase in serum T(3) and T(4) levels. Glibenclamide did not significantly alter alloxan-induced hypothyroidism. In conclusion our data suggest that cromakalim and glibenclamide produce some metabolic effects that are either not related to K(ATP) channel modulation or may involve different sub-types of potassium channels. Further glibenclamide when combined with cromakalim may not be beneficial in a condition when diabetes mellitus and hypertension co-exits.