Genotoxicity testing of a Salacia oblonga extract.

Salacia oblonga has been used for thousands of years in Ayurvedic medicine for the oral treatment of diabetes. The root extract has been shown to inhibit the activity of intestinal alpha-glucosidases, therefore S. oblonga holds potential as a natural method to mitigate the blood glucose response for people with diabetes. As part of a safety evaluation of novel ingredients for use in blood glucose control, the potential genotoxicity of a S. oblonga root extract (SOE) was evaluated using the standard battery of tests (reverse mutation assay; chromosomal aberrations assay; mouse micronucleus assay) recommended by US Food and Drug Administration (FDA) for food ingredients. SOE was determined not to be genotoxic under the conditions of the reverse mutation assay and mouse micronucleus assay, and weakly positive for the chromosomal aberrations assay. A reproducible, although weak, positive chromosomal aberrations response in human lymphocytes is of concern and further toxicity research is recommended. Use of SOE is presently expected to be safe, as anticipated intake is small compared to the doses administered in the genotoxicity assays and may, after further toxicity research, may prove be a useful ingredient in foodstuffs.     

Safety evaluation of an extract from Salacia oblonga.

Plant extracts from the Salacia genus have been found to have intestinal alpha-glucosidase inhibitor activity, which may have application to the development of medical foods for people with diabetes. We evaluated the safety of a hot water extract of S. oblonga (salacinol extract) supplemented to or processed into a medical food. Thirty male Sprague-Dawley rats were assigned among one of three treatments: (1) EN-0178 (control, liquid diet), (2) EN-0178+salacinol (as 1 plus 500 mg of salacinol extract per 253 g diet, which was added to product immediately prior to feeding), (3) EN-0195 (as 1 plus 500 mg of salacinol extract per 253 g diet, which was added during product manufacture). After 14 days of free access to dietary treatments, rats were sacrificed, blood collected and organs weighed. Rats consuming salacinol extract had reduced (P <0.05) weight gain and feed intake. The relative (% of body weight) testicular weight was higher (P<0.05) for rats consuming salacinol extract, whereas, the relative liver and spleen weight was lower (P<0.05) for rats consuming salacinol extract. Of the serum chemistries analyzed, blood urea nitrogen and alkaline phosphatase was lower (P<0.05) for rats consuming salacinol extract. No differences in blood hematology were found. We conclude that salacinol extract, in a medical food consumed for 2 weeks in amounts estimated at 10-fold greater than proposed for human intake, did not result in clinical chemistry or histopathologic indications of toxic effects in male Sprague-Dawley rats.     

Anti-peroxidative and hypoglycaemic activity of salacia oblonga extract in diabetic rats

Hypoglycaemic activity of a petroleum ether extract of the root bark of Salacia oblonga Wall. (Celastraceae) (SOB) was studied in streptozotocin (STZ) hyperglycaemic rats. In addition, the anti-lipid peroxidative activity of SOB was studied in hyperglycaemic rats. The extract showed significant hypoglycaemia ( p < 0.001), which was supported by an insulin assay. A detailed biochemical study (thiobarbituric acid reactive substances, hydroperoxides, conjugated dienes, glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) in the renal tissue of diabetic animals treated with SOB demonstrated promising anti-lipid peroxidative activity. These results suggest that S. oblonga root bark possesses anti-diabetic and anti-peroxidative principles, and may be of value in the treatment of diabetes and associated renal complications.     

Hypoglycaemic effect of Melothria heterophylla in streptozotocin-induced diabetic rats

Context: In the Indian traditional system of medicine, Melothria heterophylla (Lour.) Cogn., (Cucurbitaceae) is prescribed for the treatment of diabetes mellitus.

Objective: In the present study, the antidiabetic effect of ethanol extract of Melothria heterophylla (EEMH), and its active isolated constituents were investigated in streptozotocin (STZ)-induced diabetic Swiss albino rats.

Method: Successive Soxhlet extraction of the dried total aerial parts with petroleum ether for defatting and then with ethanol (95%) to obtain ethanol extract, which was concentrated under reduced pressure. Hyperglycemia was induced in rats by STZ (50 mg/kg, body weight). Twenty-four hours after STZ induction, respective groups of diabetic rats received EEMH (200 and 400 mg/kg, body weight), gallic acid (GA) (2 and 4 mg/kg, body weight), and rutin (RU) (2 and 4 mg/kg, body weight), respectively, orally daily for 15 days. Glibenclamide (0.5 mg/kg, orally) served as reference. Blood glucose levels and change in body weight were measured on every 5^th day during 15 days of treatment. Biochemical parameters, viz., serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), alkaline phosphatase (ALP) and serum insulin, were measured.

Results: EEMH and its active constituents significantly (p < 0.01) normalized blood glucose levels and serum biochemical parameters as compared to those of STZ controls. Both GA (4 mg/kg) and RU (4 mg/kg) exhibited maximum glucose lowering effect (69.1 and 66.7%, respectively) in diabetic rats compared to the other dose (2 mg/kg) at the end of the study. EEMH, gallic acid and RU also showed significant increase in serum insulin, and body weight of STZ-induced diabetic rats.

Conclusion: Therefore, ethanol extract of Melothria heterophylla, GA and RU demonstrated remarkable antidiabetic activity in STZ-induced diabetic rats.     

Hypoglycaemic effect of Melothria heterophylla in streptozotocin-induced diabetic rats

Context: In the Indian traditional system of medicine, Melothria heterophylla (Lour.) Cogn., (Cucurbitaceae) is prescribed for the treatment of diabetes mellitus. Objective: In the present study, the antidiabetic effect of ethanol extract of Melothria heterophylla (EEMH), and its active isolated constituents were investigated in streptozotocin (STZ)-induced diabetic Swiss albino rats. Method: Successive Soxhlet extraction of the dried total aerial parts with petroleum ether for defatting and then with ethanol (95%) to obtain ethanol extract, which was concentrated under reduced pressure. Hyperglycemia was induced in rats by STZ (50 mg/kg, body weight). Twenty-four hours after STZ induction, respective groups of diabetic rats received EEMH (200 and 400 mg/kg, body weight), gallic acid (GA) (2 and 4 mg/kg, body weight), and rutin (RU) (2 and 4 mg/kg, body weight), respectively, orally daily for 15 days. Glibenclamide (0.5 mg/kg, orally) served as reference. Blood glucose levels and change in body weight were measured on every 5(th) day during 15 days of treatment. Biochemical parameters, viz., serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), alkaline phosphatase (ALP) and serum insulin, were measured. Results: EEMH and its active constituents significantly (p < 0.01) normalized blood glucose levels and serum biochemical parameters as compared to those of STZ controls. Both GA (4 mg/kg) and RU (4 mg/kg) exhibited maximum glucose lowering effect (69.1 and 66.7%, respectively) in diabetic rats compared to the other dose (2 mg/kg) at the end of the study. EEMH, gallic acid and RU also showed significant increase in serum insulin, and body weight of STZ-induced diabetic rats. Conclusion: Therefore, ethanol extract of Melothria heterophylla, GA and RU demonstrated remarkable antidiabetic activity in STZ-induced diabetic rats.     

Hypoglycaemic effect of Calamintha officinalis Moench. in normal and streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effects of a water extract from the aerial parts of Calamintha officinalis Moench., after either a single dose or daily oral administration for 15 days, on plasma blood glucose concentrations and basal insulin levels in normal and streptozotocin-induced diabetic rats (STZ diabetic rats). The results clearly demonstrated the hypoglycaemic effect of this plant extract in both normal and STZ diabetic rats. In addition, no changes were observed in basal plasma insulin concentrations after treatment with this plant in normal or STZ diabetic rats, indicating that the underlying mechanism of the plant's pharmacological action seems to be independent of insulin secretion. We conclude that the aqueous C. officinalis extract exhibits a significant hypoglycaemic effect in normal and STZ diabetic rats without affecting basal plasma insulin concentrations, and supports, therefore, its traditional use by the Moroccan population.     

Hypoglycaemic effects of antidiabetic drugs in streptozotocin-nicotinamide-induced mildly diabetic and streptozotocin-induced severely diabetic rats

In this study, streptozotocin-induced severely diabetic rats and streptozotocin-nicotinamide-induced mildly diabetic rats were established to compare their characteristics and to investigate the hypoglycaemic effects of antidiabetic drugs. Results show that in streptozotocin-induced severely diabetic rats, the pancreatic insulin content decreased to approximately 10% of that in normal rats. These severely diabetic rats also exhibited marked hyperglycaemia and impaired glucose tolerance due to insulin secretory deficiency. In contrast, the pancreatic insulin content was approximately 50% of normal levels in streptozotocin-nicotinamide-induced mildly diabetic rats. These mildly diabetic rats exhibited moderate hyperglycaemia and impaired glucose tolerance due to loss of early-phase insulin secretion. Voglibose (alpha-glucosidase inhibitor), metformin (biguanide), glibenclamide (sulfonylurea), sitagliptin (dipeptidyl peptidase-4 inhibitor) and insulin significantly improved glucose tolerance in streptozotocin-nicotinamide-induced mildly diabetic rats. In contrast, in streptozotocin-induced severely diabetic rats, voglibose, metformin and insulin significantly improved glucose tolerance, but no significant effect was observed for glibenclamide and sitagliptin due to a decreased insulinotropic effect. These results suggest that streptozotocin-nicotinamide-induced mildly diabetic rats, which exhibit a mild decline in glucose tolerance due to loss of early-phase insulin secretion, are sensitive to the hypoglycaemic effects of insulinotropic agents and have many pathological features resembling type 2 diabetes, which may be useful in the pharmacological investigation of numerous antidiabetic drugs.     

Neuroprotective effect of ginger on anti-oxidant enzymes in streptozotocin-induced diabetic rats

The aim of the present study was to investigate the effect of ginger on oxidative stress markers in the mitochondrial fractions of cerebral cortex (CC), cerebellum (CB), hippocampus (HC) and hypothalamus (HT) of diabetic rats. Diabetes exacerbates neuronal injury induced by hyperglycemia mediated oxidative damage. A marked decrease in anti-oxidant marker enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced glutathione (GSH) and increase in malondialdehyde (MDA) was observed in the diabetic rats. Decreased activities of anti-oxidant enzymes in diabetic rats were augmented on oral administration of ginger. Moreover, ginger administration depleted the MDA level, which was earlier increased in the diabetic rats. These results suggest that ginger exhibit a neuroprotective effect by accelerating brain anti-oxidant defense mechanisms and down regulating the MDA levels to the normal levels in the diabetic rats. Thus, ginger may be used as therapeutic agent in preventing complications in diabetic patients.     

Toxicological and cytogenetic assessment of a Salacia oblonga extract in a rat subchronic study.

Salacia oblonga holds potential as a natural method to mitigate the blood glucose response for people with diabetes by inhibiting the activity of intestinal alpha-glucosidases. As part of a safety evaluation of novel ingredients for use in blood glucose control, the toxicity of a S. oblonga root extract (SOE) was evaluated in a subchronic 90-day feeding study in rats. An in vivo-in vitro rat peripheral blood lymphocyte chromosomal aberrations assay was added at termination of the subchronic rat study to examine cultured lymphocytes for possible chromosomal aberration induction. This was conducted due to a previous weak; although reproducible, positive chromosomal aberrations response in cultured peripheral blood human lymphocytes after acute in vitro treatment with SOE. The present study results indicate that SOE was negative for the induction of chromosomal aberrations in cultured rat peripheral blood lymphocytes after 90 consecutive days of treatment with SOE. The no observable adverse effect level (NOAEL) was determined to be 2,500 mg/kg/day following daily subchronic oral gavage administrations to rats.     

Hypoglycaemic effect of quinolizidine alkaloids--lupanine and 2-thionosparteine on non-diabetic and streptozotocin-induced diabetic rats

The effects of the highly selective histamine H4 receptor antagonists JNJ7777120 and VUF6002 were investigated on the carrageenan-induced inflammation and thermal hyperalgesia in rats. JNJ7777120 (10 and 30 mg/kg, s.c.) and VUF6002 (10 mg/kg, s.c.) significantly reduced paw edema and hyperalgesia provoked by subplantar injection of carrageenan; the effect was evident against the early (2 h) phase of inflammation. An inactive analog of VUF6002, VUF6007 (10 mg/kg, s.c.) slightly aggravated paw edema, while leaving unaltered carrageenan-induced nociception. These findings indicate that histamine H4 receptors participate in the early phase of acute inflammation induced by carrageenan in rats, influencing both edema and thermal hyperalgesia.     

Salacia oblonga root improves postprandial hyperlipidemia and hepatic steatosis in Zucker diabetic fatty rats: activation of PPAR-alpha

Salacia oblonga (SO) root is an Ayurvedic medicine with anti-diabetic and anti-obese properties. Peroxisome proliferator-activated receptor (PPAR)-alpha, a nuclear receptor, plays an important role in maintaining the homeostasis of lipid metabolism. Here, we demonstrate that chronic oral administration of the water extract from the root of SO to Zucker diabetic fatty (ZDF) rats, a genetic model of type 2 diabetes and obesity, lowered plasma triglyceride and total cholesterol (TC) levels, increased plasma high-density lipoprotein levels and reduced the liver contents of triglyceride, non-esterified fatty acids (NEFA) and the ratio of fatty droplets to total tissue. By contrast, the extract had no effect on plasma triglyceride and TC levels in fasted ZDF rats. After olive oil administration to ZDF the extract also inhibited the increase in plasma triglyceride levels. These results suggest that SO extract improves postprandial hyperlipidemia and hepatic steatosis in ZDF rats. Additionally, SO treatment enhanced hepatic expression of PPAR-alpha mRNA and protein, and carnitine palmitoyltransferase-1 and acyl-CoA oxidase mRNAs in ZDF rats. In vitro, SO extract and its main component mangiferin activated PPAR-alpha luciferase activity in human embryonic kidney 293 cells and lipoprotein lipase mRNA expression and enzyme activity in THP-1 differentiated macrophages; these effects were completely suppressed by a selective PPAR-alpha antagonist MK-886. The findings from both in vivo and in vitro suggest that SO extract functions as a PPAR-alpha activator, providing a potential mechanism for improvement of postprandial hyperlipidemia and hepatic steatosis in diabetes and obesity.     

Hypoglycemic activity of aqueous seed extract of Hunteria umbellata in normal and streptozotocin-induced diabetic rats

The present study evaluated the aqueous seed extract of Hunteria umbellata K. Schum (Apocynaceae) for hypoglycemic activity in rats. Diabetes was induced by a single dose of streptozotocin (50?mg/kg i.p.). Daily doses of 400, 800, and 1000?mg/kg of extract were orally administered to fasted normal and diabetic rats. Blood glucose levels were monitored after 0, 2, 4, 8, 12?h and on day 14 post treatment. Liver glycogen levels were also estimated on day 14. In normal rats, only 400?mg/kg of the extract produced a significant reduction in blood glucose at the 4?h (P?<?0.05) which was 22.15?±?4.88%. In diabetic rats, the extract, 400, 800?mg/kg, caused significant reduction (P?<?0.01), 51.87% ± 5.79% and 43.47% ± 8.06% respectively, with maximum effect at 8?h. This reduction in blood glucose was greater than that of glibenclamide (31.03% ± 8.86%). Diabetic rats administered with 400?mg/kg extract produced a significant reduction (P?<?0.01) on day 14 (43.60% ± 8.10%). Liver glycogen levels were significantly increased (P?<?0.05) in diabetic rats administered with doses of 400 and 800?mg/kg extracts and these were comparable to glibenclamide. Acute toxicity data showed no mortality in mice up to 17.5?g/kg. We conclude that the extract possesses marked hypoglycemic effects in diabetic rats possibly through increased glycogenesis, thus justifying its use in herbal medicine for the treatment of diabetes.     

Renoprotective effect of aged garlic extract in streptozotocin-induced diabetic rats

Objective:

Aged garlic extract (AGE) has been proven to exhibit antioxidant, hypolipidemic, hypoglycemic and antidiabetic properties. However, its effect on diabetic nephropathy was unexplored. Therefore, the present study was designed to investigate the renoprotective effect of AGE in streptozotocin-induced diabetic rats.

Materials and Methods:

Albino Wistar rats were induced with diabetes by a single intraperitoneal injection of 45 mg/kg b.w. of streptozotocin. Commercially available AGE was supplemented orally at a dose of 500 mg/kg body weight/day. Aminoguanidine, which has been proven to be an anti-glycation agent was used as positive control and was supplemented at a dose of 1 g/L in drinking water. The serum and urinary biochemical parameters were analyzed in all the groups and at the end of 12 weeks follow up, the renal histological examination were performed using H & E and PAS staining.

Results:

The diabetic rats showed a significant change in the urine (P < 0.001) and serum (P < 0.01) constituents such as albumin, creatinine, urea nitrogen and glycated hemoglobin. In addition, the serum lipid profile of the diabetic rats were altered significantly (P < 0.05) compared to that of the control rats. However, the diabetic rats supplemented with aged garlic extract restored all these biochemical changes. The efficacy of the extract was substantiated by the histopathological changes in the kidney.

Conclusion:

From our results, we conclude that aged garlic extract has the ability to ameliorate kidney damage in diabetic rats and the renoprotective effect of AGE may be attributed to its anti-glycation and hypolipidemic activities.KEY WORDS: Aged garlic extract, anti-glycation, diabetes, diabetic nephropathy, hypolipidemic, renoprotective     

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 200 mg/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 200 mg/kg than 50 mg/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.     

Hypoglycaemic activity of an aqueous extract from ficus carica (fig tree) leaves in streptozotocin diabetic rats

To investigate the hypoglycaemic activity of Ficus carica leaf aqueous extract, a decoction was administred to rats in lieu of drinking water for three weeks. The groups were: untreated non-diabetic (n = 13), untreated diabetic (n = 13), treated non-diabetic (n =13) and treated diabetic (n = 13) animals. The extract decreased (p < 0.025) plasma glucose in diabetic (27.9 ± 4.5 mmol/L to 19.6 ± 9.9 mmol/L) while not in normal rats. Plasma insulin levels were decreased by treatment (p < 0.05) in non-diabetic rats from 4.9± 1.6 ng/mL to 3.3 ± 1.2 ng/mL. Glucose uptake (μmol/min) by rat hindquarters perfused was: 5.9 ± 2.2 (untreated non-diabetic rats), 4.8 ± 2.3 (treated non-diabetic rats, p < 0.05 vs. untreated non-diabetic rats), 2.0 ± 2.0 (untreated diabetic rats, p < 0.01 vs. untreated non-diabetic rats) and 4.1 ± 3.6 (treated diabetic rats) in absence of insulin; 7.0 ± 1.7 (untreated non-diabetic rats), 8.3 ± 0.8 (treated non-diabetic rats, p < 0.05 vs. untreated non-diabetic rats), 5.0 ± 1.6 (untreated diabetic rats, p < 0.05 vs. untreated non-diabetic rats) and 6.4 ± 2.4 (treated diabetic rats) in presence of insulin. Lactate released was lower in untreated diabetic vs. untreated non-diabetic rats. Thus, Ficus carica extract showed a clear hypoglycaemic effect in diabetic rats. Such an effect cannot be mediated by an enhanced insulin secretion, so an as yet undefined insulin-like peripheral effect, may be suggested.     

Hypoglycemic and antioxidant effects of Rheum franzenbachii extract in streptozotocin-induced diabetic rats

The hypoglycemic and antioxidant effects of ethanol extract from the roots and rhizomes of Rheum franzenbachii Münt. (Polygonaceae) were evaluated in streptozotocin-induced diabetic rats. Effects of repeated oral administration of ethanol extract (125, 250, and 500?mg/kg body weight) on the plasma glucose level (PGL), oral glucose tolerance test (OGTT), malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in diabetic rats were examined. It was found that administration of ethanol extract (125, 250, and 500?mg/kg) produced a significant fall in PGL, AUC, and MDA, while elevating the GSH levels and SOD and CAT activities in diabetic rats. The dose of 500?mg/kg was identified as the most effective dose, with a decrease of 65.8 and 44.0% in PGL and MDA, and elevation of 72.6, 75.0, and 51.5% in GSH level and SOD and CAT activities, respectively, after 14 days of ERF administration in diabetic rats. Moreover, the OGTT studies showed a maximum reduction in PGL and AUC. From the active extract of Rheum franzenbachii, two stilbenes, desoxyrhapontigenin (1) and desoxyrhaponticin (2), were isolated as major constituents. The present study concludes that the ethanol extract of roots and rhizomes from Rheum franzenbachii had significant hypoglycemic and antioxidant effects.     

Antihyperglycemic activity of Caralluma tuberculata in streptozotocin-induced diabetic rats

The current study aimed at evaluating the potential and mechanisms of the antidiabetic activity of the methanolic extract (ME) of Caralluma tuberculata as well as its chloroform (CF), n-butanol (BF) and the remaining water fractions (RFs) in streptozotocin-induced diabetic rats. The antidiabetic activity was evaluated through assessing fasting blood glucose (FBG), insulin levels, oral glucose tolerance test (OGTT), glucose utilization by isolated rat psoas muscle, gut glucose absorption and G-6-Pase activity in isolated rat liver microsomes. Both ME and RF showed the highest potency, where ME had superior activity. The mechanism underlying the observed antihyperglycemic activity of ME could be attributed, at least in part, to enhanced skeletal muscle utilization of glucose, inhibition of hepatic gluconeogenesis and stimulation of insulin secretion. ME was standardized through LC–MS analysis for its major pregnanes.     

Altered activity of hepatic mixed-function mono-oxygenase enzymes in streptozotocin-induced diabetic rats.

1. In streptozotocin-induced diabetic male rats, hepatic microsomal aminopyrine N-demethylase activity was depressed, whereas aniline hydroxylase activity and cytochrome P-450 content were increased over control values. 2. In diabetic female rats, hepatic microsomal aminopyrine N-demethylase activity, aniline hydroxylase activity, biphenyl 4-hydroxylase activity, and cytochrome P-450 content were increased over control values. 3. Insulin treatment of diabetic male and female rats antagonized all physical and biochemical abnormalities of the diabetic state; 4. Methyl analogues of streptozotocin did not produce a diabetic state when injected into female rats, and resulted in no changes in aminopyrine N-demethylase activity, aniline hydroxylase activity, or cytochrome P-450 content. 5. Insulin treatment of non-diabetic female rats resulted in slight decreases in aminopyrine N-demethylase and aniline hydroxylase activities, but no changes in cytochrome P-450 content. These observations suggest that insulin primarily influences drug metabolism of diabetic animals through correction of the insulin-deficient diabetic state.