In vitro evaluation of free radical scavenging activity of Codariocalyx motorius root extract.

OBJECTIVE: To determine the phenolic content in Codariocalyx motorius root extract and to evaluate its antioxidant properties using various in vitro assay systems. METHODS: The antioxidant activity was evaluated based on scavenging of 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, reducing power and by inhibition of lipid peroxidation which was estimated in terms of thiobarbituric acid reactive substances. RESULTS: The root extract of the Codariocalyx motorius (C. motorius) exhibited potent total antioxidant activity that increased with increasing amount of extract concentration, which was compared with standard drug such as quercetin, butylated hydroxytoluene, tocopherol at different concentrations. The different concentrations of the extracts showed inhibition on lipid peroxidation. In addition, the extracts had effective reducing power, free radical scavenging, super oxide anion scavenging, nitric oxide scavenging, lipid peroxidation, and total phenolic content depending on concentration. High correlation between total phenolic contents and scavenging potential of different reactive oxygen species (r(2)=0.831-0.978) indicated the polyphenols as the main antioxidants. CONCLUSIONS: Codariocalyx motorius (C. motorius) root possess the highly active antioxidant substance which can be used for the treatment of oxidative stress-related diseases.

Oxidative stress-mediated cytotoxicity and apoptosis induction by TiO2 nanofibers in HeLa cells.

Titanium dioxide nanoparticles are increasingly being used in pharmaceutical and cosmetic products. The high aspect ratio of fibrous nanomaterials, such as carbon nanotubes and TiO(2) nanofibers (TiO(2)NFs), similar to the one used in this study makes them an attractive structural material and has attracted a lot of attention due to their possible negative health effects as suggested by their morphological similarities with asbestos. In the present study, therefore, toxicity of TiO(2)NFs was evaluated in human cervical adenocarcinoma HeLa cells. The TEM and XRD analyses showed that TiO(2)NFs used in this study are pure with uniform diameter of around 200 nm, and their length to width aspect ratio ranged between 5 and 15. Exposure of HeLa cells to TiO(2)NFs induced significant cytotoxicity even at doses as low as 2 µg/ml. The intracellular uptake of TiO(2)NFs in cells was shown by Alizarin Red S (ARS) labeled nanofibers. The mechanism of toxicity is mainly due to the induction of cellular oxidative stress, as revealed by elevated ROS levels, reduced antioxidant levels, and increased lipid peroxidation leading to apoptosis. The cell cycle analysis indicated G(2)/M cell cycle arrest in the cells exposed to TiO(2)NF. TiO(2)NFs treatment to HeLa cells resulted in increased expression of proapoptotic proteins Bax with an increase in cytosolic Cytochrome-C and inhibition of anti-apoptotic protein Bcl-2. Our results revealed the potential mechanism of cellular effects of TiO(2)NFs.

Antidiabetic activity of alcoholic stem extract of Gymnema montanum in streptozotocin-induced diabetic rats.

In the present study, the effect of alcoholic stem extract of Gymnema montanum (GMSt) on blood glucose, plasma insulin, and carbohydrate metabolic enzymes were studied in experimental diabetes. Diabetes mellitus was induced by a single intraperitoneal injection of STZ (60 mg/kg bw). Five days after STZ induction, diabetic rats received GMSt orally at the doses of 25, 50, 100 and 200mg/kg daily for 3 weeks. Graded doses of stem extract showed a significant reduction in blood glucose levels and improvement in plasma insulin levels. The effect was more pronounced in 100 and 200mg/kg than 50mg/kg. GMSt showed significant increase in hexokinase, Glucose-6-phosphate dehydrogenase and glycogen content in liver of diabetic rats while there was significant reduction in the levels of glucose-6-phosphatase and fructose-1,6-bisphosphatase. The present study clearly indicated significant antidiabetic effect with the stem extract of G. montanum and lends support for its traditional usage.

SIRT1 activation by resveratrol ameliorates cisplatin-induced renal injury through deacetylation of p53.

Nephrotoxicity is one of the important dose-limiting factors during cisplatin treatment. There is a growing body of evidence that activation of p53 has a critical role in cisplatin-induced renal apoptotic injury. The nicotinamide adenine dinucleotide-dependent protein deacetylase SIRT1 decreases apoptosis through deacetylating of p53, and resveratrol is known as an activator of SIRT1. To study the role of SIRT1 in cisplatin-induced renal injury through interaction with p53, mouse proximal tubular cells (MPT) were treated with cisplatin and examined the expression level of SIRT1, acetylation of p53, PUMA-α, Bax, the cytosolic/mitochondrial cytochrome c ratio, and active caspase-3. The expression of SIRT1 was decreased by cisplatin. Resveratrol, a SIRT1 activator, ameliorated cisplatin-induced acetylation of p53, apoptosis, and cytotoxicity in MPT cells. In addition, resveratrol remarkably blocked cisplatin-induced decrease of Bcl-xL in MPT cells. Further specific SIRT1 inhibition with EX 527 or small interference RNA specific to SIRT1 reversed the effect of resveratrol on cisplatin-induced toxicity. Inhibition of p53 by pifithrin-α reversed the effect of EX527 in protein expression of PUMA-α, Bcl-xL, and caspase-3 and cytotoxicity in MPT cells. SIRT1 protein expression after cisplatin treatment was significantly decreased in the kidney. SIRT1 activation by resveratrol decreased cisplatin-induced apoptosis while improving the glomerular filtration rate. Taken together, our findings suggest that the modulation of p53 by SIRT1 could be a possible target to attenuate cisplatin-induced kidney injury.

Antioxidant potential of Amorphophallus paeoniifolius in relation to their phenolic content.

The present study evaluates the antioxidative and radical scavenging potential of the tuber extract of Amorphophallus paeoniifolius (Dennst.) Nicolson, (Araceae). The ethanol extract of A. paeoniifolius (APE) was studied for the inhibition of lipid peroxidation estimated in terms of thiobarbituric acid reactive substances (TBARS) and the levels were reduced by 4.3% to 67.2% in a dose-dependent manner. Further, APE was analyzed for scavenging capacities based on 1,1-diphenyl-2-picrylhydrazyl-2-radical (DPPH) assay and percentage inhibition activity based on 2,2-azinobis-(-3-ethyl) benzo-thiozoline-6-sulfonate (ABTS+) and H2O2. The A. paeoniifolius extract showed a maximum of 68.6% of DPPH scavenging activity and the maximum inhibition of 74% and 67.2% in the case of ABTS and H2O2, respectively. The antioxidant efficiency and inhibition of oxidation of the extract was found to be dose-dependent at the tested concentrations of 1-50 microg/mL. High-performance thin layer liquid chromatography (HPTLC) profile of the extract suggests the presence of polyphenols such as gallic acid, resveratrol, quercetin and two unidentified compounds. The results suggest that the ethanol extract of A. paeoniifolius has a potent antioxidant activity in vitro and can be utilized as an effective and safe source of antioxidants.

Protective effect of Gymnema montanum against renal damage in experimental diabetic rats.

Gymnema montanum Hook (Asclepiadaceae), is an endemic plant species of India, traditionally used for diabetes and its management. In this experiment, the ethanol extract of G. montanum (GLEt) at a dose of 200mg/kg body weight was tested to evaluate its effect on renal damage in alloxan-induced diabetic rats and the efficacy was compared with standard hypoglycemic drug, glibenclamide (600 microg/kg body weight). The GLEt and glibenclamide were administered orally for 3 weeks and the effects on glucose, insulin, renal markers including urea, creatinine and uric acid, lipid peroxidation markers including thiobarbituric reactive substances (TBARS) and hydroperoxides and antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities in kidney were studied. In addition, the urinary protein profile was studied using SDS-PAGE. The results indicated that the GLEt significantly normalized the elevated blood glucose, renal markers and lipid peroxidation markers and increased antioxidant levels in diabetic kidney. The diabetic rats excreted large amount of proteins than untreated rats which was normalized during the treatment with GLEt. In conclusion, the GLEt was found to be more effective in reducing oxidative stress, thus confirming the ethnopharmacological use of G. montanum in protecting diabetes and its complications.

Antidiabetic effects of scoparic acid D isolated from Scoparia dulcis in rats with streptozotocin-induced diabetes.

We evaluated the antihyperglycaemic effect of scoparic acid D (SAD), a diterpenoid isolated from the ethanol extract of Scoparia dulcis in streptozotocin (STZ)-induced diabetic male Wistar rats. SAD was administered orally at a dose of 10, 20 and 40 mg kg(-1) bodyweight for 15 days. At the end of the experimental period, the SAD-treated STZ diabetic rats showed decreased levels of glucose as compared with diabetic control rats. The improvement in blood glucose levels of SAD-treated rats was associated with a significant increase in plasma insulin levels. SAD at a dose of 20 mg kg(-1) bodyweight exhibited a significant effect when compared with other doses. Further, the effect of SAD was tested on STZ-treated rat insulinoma cell lines (RINm5F cells) and isolated islets in vitro. SAD at a dose of 20 microg mL(-1) evoked two-fold stimulation of insulin secretion from isolated islets, indicating its insulin secretagogue activity. Further, SAD protected STZ-mediated cytotoxicity and nitric oxide (NO) production in RINm5F cells. The present study thus confirms the antihyperglycaemic effect of SAD and also demonstrated the consistently strong cytoprotective properties of SAD.

Potential in vitro antioxidant and protective effects of Gymnema montanum H. on alloxan-induced oxidative damage in pancreatic beta-cells, HIT-T15.

The present study describes the antioxidant activities of ethanol extract from Gymnema montanum (GLEt) which is an endemic plant of India. Antioxidant activity of the GLEt was studied in vitro based on scavenging of hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, reducing power and inhibition of lipid peroxidation estimated in terms of thiobarbituric acid reactive substances (TBARS). Further, we examined its protective effect against alloxan-induced oxidative stress in pancreatic beta-cells, HIT-T15 by measuring the free radical generation, malonaldehyde formation and antioxidant levels such as CAT, GPx and GSH. Results showed that G. montanum leaves exhibited significant antioxidant activities measured by various in vitro model systems. The HIT-T15 cell line studies showed the tendency of GLEt to increase antioxidant levels meanwhile decrease the free radical formation and inhibit the lipid peroxidation. The antioxidant activity was found to be well correlated with the phenolic phytochemicals present in the extract. GC-MS analyses revealed the presence of few phenolic compounds in the extract. As this plant has already been demonstrated for a variety of medicinal properties from our laboratory, results of this study suggest that G. montanum is an interesting source for antioxidant compounds and useful for various therapeutic applications.

Antihyperlipidaemic effect of Gymnema montanum: a study on lipid profile and fatty acid composition in experimental diabetes.

In the present study, the antihyperlipidaemic efficacy of ethanol extract of Gymnema montanum leaves was investigated in alloxan-induced diabetic rats and the effect was compared to standard hypoglycaemic drug, glibenclamide. Male adult albino Wistar rats were injected with freshly prepared solution of alloxan monohydrate (150 mg/kg body weight) to induce diabetes. After 2 weeks, the rats with moderate diabetes were administered G. montanum leaves (200 mg/kg body weight) for 21 days by gastric lavage, after which serum, liver and kidney samples were analysed for lipid profile, lipoprotein changes and fatty acid composition. While the alloxan-induced diabetic rats showed a significant increase in the levels of cholesterol, triglycerides and free fatty acids, the levels in the animals treated with G. montanum leaves were considerably reduced and restored to near normal values. Antihyperlipidaemic effects of G. montanum leaves were found to be comparable with that of glibenclamide. Similarly, G. montanum leaves treatment resulted in reversal of alterations observed in the plasma lipoproteins (high-density lipoprotein, low-density lipoprotein and very high-density lipoprotein-cholesterol) and fatty acid composition in serum, liver and kidney of alloxan-induced rats. Our study suggests that phytochemicals present in G. montanum may play an important role in suppressing the elevated lipid profile in diabetes and may be useful for the prevention and/or early treatment of diabetes-associated hyperlipidaemia.

N-Benzoyl-D-phenylalanine attenuates brain acetylcholinesterase in neonatal streptozotocin-diabetic rats.

The effect of hyperglycaemia due to experimental diabetes in male Wistar rats causes a decrease in the level of acetylcholinesterase (AChE) with significant increase in lipid peroxidative markers: thiobarbituric acid-reactive substances (TBARS) and hydroperoxides in brains of experimental animals. The decreased activity of both salt soluble and detergent soluble acetylcholinesterase observed in diabetes may be attributed to lack of insulin which causes specific alterations in the level of neurotransmitter, thus causing brain dysfunction. Administration of non-sulfonylurea drug N-benzoyl-D-phenylalanine (NBDP) could protect against direct action of lipid peroxidation on brain AChE and in this way it might be useful in the prevention of cholinergic neural dysfunction, which is one of the major complications in diabetes.

Modulation of impaired cholinesterase activity in experimental diabetes: effect of Gymnema montanum leaf extract.

We reported that a leaf extract (GLEt) obtained from an anti-diabetic plant, Gymnema montanum, an endangered species endemic to India, has anti-peroxidative and antioxidant effects on diabetic brain tissue in rats. Here we examined the effect of the extract on the activity of reduced brain and retinal acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in streptozotocin (STZ)-induced diabetic male Wistar rats. Diabetic rats received GLEt orally (200 mg/kg bwt/d) for 12 wk, and changes in blood glucose, plasma insulin, the lipid peroxidation marker thiobarbituric acid-reactive substance (TBARS), and AChE and BChE activity were measured. The results confirmed prior reports that hyperglycemia significantly enhances TBARS levels in brain and retinal tissue and decreases AChE and BChE activity. Treatment with GLEt significantly reversed the impairment in enzymatic activity in addition to reducing the level of TBARS, suggesting that GLEt protects against the adverse effect of lipid peroxidation on brain and retinal cholinesterases. We suggest that GLEt could be useful for preventing the cholinergic neural and retinal complications of hyperglycemia in diabetes.

Modulatory effect of Gymnema montanum leaf extract on brain antioxidant status and lipid peroxidation in diabetic rats.

The effects of leaf extract from Gymnema montanum, an endangered and endemic plant, were examined on brain lipid peroxidation in experimental diabetic rats. Ethanolic extract of G. montanum leaves was administered orally (50, 100, and 200 mg/kg of body weight) for 3 weeks, and changes in blood glucose, plasma insulin, and lipid peroxidation markers such as thiobarbituric acid-reactive substances (TBARS), hydroperoxides, and levels of antioxidants, namely, superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and glutathione-S-transferase, were examined in the brain of alloxan-induced diabetic rats. Glibenclamide was used as a standard reference drug. A significant increase in the activities of antioxidants was observed in brain on treatment with G. montanum leaf extract and glibenclamide for 3 weeks. Both the treated groups showed significant decreases in formation of TBARS and hydroperoxides in brain, suggesting a role in protective action against lipid peroxidation-mediated membrane damage. Our findings indicate that G. montanum leaf extract possesses antiperoxidative and antioxidant effects in addition to its antidiabetic activity. This report helps to create awareness on the need for conservation of medicinal plants, and G. montanum is one such plant that needs to be conserved through various propagation trials.

Effect of Gymnema montanum on blood glucose, plasma insulin, and carbohydrate metabolic enzymes in alloxan-induced diabetic rats.

The effects of Gymnema montanum, an endangered plant used in the ancient period of India, on blood glucose, plasma insulin, and carbohydrate metabolic enzymes were studied in alloxan diabetic rats. Administration of alcoholic extract of G. montanum leaves (50, 100, 200 mg/kg body weight) to alloxan diabetic rats for 3 weeks reduced the blood glucose level. Administration of G. montanum leaf extract (GLEt) at 200 mg/kg body weight significantly decreased the blood glucose levels and significantly increased the plasma insulin levels. This clearly shows the antidiabetic efficacy of GLEt, which was better than that of glibenclamide.