Hypoglycaemic activity of Nelumbo nucifera gaertn. (Fam. Nymphaeaceae) rhizome (methanolic extract) in streptozotocin-induced diabetic rats

The hypoglycaemic effect of the rhizome extract of Nelumbo nucifera was studied in streptozotocin-induced diabetic rats. A methanol extract of the plant obtained by soxhlet extraction from finely pulverized rhizomes was used. The LD₅₀ of the extract was found to be 2 g/kg. The extract (300 mg/kg and 600 mg/kg, orally) caused a reduction of blood glucose levels in streptozotocin-induced diabetic rats by 53% (p<0.001) and 55% (p<0.001) respectively at the end of 12 h. The results of this study indicate that the methanol extract of the rhizome possesses favourable hypoglycaemic activity in hyperglycaemic animals taking chlorpropamide as a standard.     

Antidiabetic and antioxidant effects of Annona muricata (Annonaceae), aqueous extract on streptozotocin-induced diabetic rats

Ethnopharmacological relevance

The leaves of Annona muricata are used in Cameroon to manage diabetes and its complications. The aim of this study was to evaluate the antidiabetic, antioxidant activities and the potential toxicity of aqueous extract of Annona muricata in streptozotocin-induced diabetic rats.

Material and methods

Oral administration of Annona muricata aqueous extract (100 mg/kg or 200 mg/kg) was studied in normal and streptozotocin-induced diabetic rats. In long term treatment, 2 weeks after streptozotocin-induced diabetic rats, animals received plant extract during 28 consecutive days. For a protective effect, extract was administered 3 days prior to streptozotocin exposure and animals were observed 2 weeks without treatment.

Results

The plant extract was not effective in normal rats. In diabetic rats, single administration of the extract significantly reduced blood glucose levels by 75% and 58.22% respectively at the dose of 100 mg/kg and 200 mg/kg as compared to the initial value. Treatment of normal rats 3 days prior to diabetes induction showed that, Annona muricata extract has no effect within 72 h following STZ injection. However, after 14 days post-treatment, the extract at the dose of 100 mg/kg significantly reduced blood glucose levels as compared with initial value and diabetic control rats. Immunohistochemical staining of pancreatic β-cells of diabetic rats treated with the dose of 100 mg/kg expressed strong staining for β-cell compared to diabetic control. In a long-term study daily administration of Annona muricata aqueous extract for 28 days to diabetic rats, reduced blood glucose levels, serum creatinine, MDA, AST, ALT activity, and nitrite levels LDL-cholesterol. Total cholesterol, triglycerides, SOD, and CAT activity contents were restored.

Conclusion

These different results show that the antidiabetic activity of Annona muricata aqueous extract can be explained by its hypolipidaemic effect, its antioxidant and protective action on pancreatic β-cells, which in turn improve glucose metabolism.     

Effect of Salvia officinalis L. leaves on serum glucose and insulin in healthy and streptozotocin-induced diabetic rats

The leaves of sage (Salvia officinalis L., Lamiaceae) are reported to have a wide range of biological activities, such as anti-bacterial, fungistatic, virustatic, astringent, eupeptic and anti-hydrotic effects. To determine the hypoglycaemic effect of sage leaves, we investigated the effects of essential oil and methanolic effect of the plant on healthy and streptozotocin-induced diabetic rats. The animals were made diabetic using by streptozotocin (70 mg/kg, i.p.). The methanolic extract (100, 250, 400 and 500 mg/kg) and essential oil (0.042, 0.125, 0.2 and 0.4 ml/kg) were injected intraperitoneally. The control groups were administered water and sunflower oil as vehicles of methanolic extract and essential oil, respectively. Blood samples were obtained from retro-orbital sinus before administration and 1, 3 and 5 h after administrations. The serum glucose was measured by the enzymatic method of glucose oxidase. The results showed that the essential oil of sage did not change serum glucose, while the plant extract significantly decreased serum glucose in diabetic rats in 3 h without effect on insulin releasing from the pancreas but not in healthy rats. Also, the LD₅₀ of the methanolic extract is measured (4000 mg/kg, i.p.). The present data indicate that sage extract has hypoglycaemic effect on diabetic animals and the plant should be considered in future therapeutic researches.     

Hypoglycaemic activity of Leucas lavandulaefolia Rees. in streptozotocin-induced diabetic rats

The antidiabetic activity of Leucas lavandulaefolia Rees (Family - Labiatae) extract on streptozotocin (STZ) induced diabetic rats has been investigated. A methanol extract of the herb at doses of 200 and 400 mg/kg, and glybenclamide (1 mg/kg) were administered concurrently to STZ-diabetic rats. The extract caused a significant reduction of blood glucose levels in streptozotocin-induced diabetic rats by 29.8% (p <0.001) compared with control groups. © 1997 John Wiley & Sons, Ltd.     

Effects of chard (Beta vulgaris L. var. Cicla) extract on pancreatic B cells in streptozotocin-diabetic rats: a morphological and biochemical study

Chard (Beta vulgaris L. var. cicla) is used as a hypoglycemic agent by diabetic patients in Turkey. The present study was carried out in order to detect whether this plant, used in folk remedies for decreasing blood glucose levels, affects pancreatic B cells and blood glucose. In the diabetic group, a decrease in the number of B cells of Langerhans islets and in the secretory materials, a swollen granular endoplasmic reticulum cisternae and widened intercellular areas in some of B cells were observed. But, in a diabetic group given chard extract, an increase in the number of B cells of Langerhans islets and in the secretory granules were noted, together with many hypertrophic Golgi apparatus and granules of low densities. The extract while having no effect on blood glucose and body weight in the normal group, reduced the blood glucose value in streptozotocin-induced hyperglycemic animals. But, in a diabetic group given chard, the body weight significantly increased in comparison to the diabetic group; maximum reduction in blood glucose levels was observed on the 42nd day. According to the morphological and biochemical results obtained, it is concluded that the extract of this plant when administered by gavage may reduce blood glucose levels by regeneration of the B cells.     

Inhibitory effect of Thymus caramanicus Jalas on hyperglycemia-induced apoptosis in in vitro and in vivo models of diabetic neuropathic pain

Ethnopharmacological relevance

Since Thymus caramanicus Jalas is used as a folk medicine for the treatment of rheumatism, skin disorders, bacterial infections and diabetes and it contain antioxidant agents, we decided to investigate the possible effects of Thymus caramanicus Jalas (TCJ) extract on in vitro and in vivo models of diabetic neuropathy.

Materials and methods

The high glucose-induced cell injury in Pheochromocytoma (PC12) cells and streptozotocin-induced diabetic rats were used. Tail-flick and rotarod treadmill assessments were used to determine nociceptive threshold and motor coordination. Cell viability was determined by MTT assay test. Western blotting was performed to measurement of apoptosis markers.

Results

The data showed that elevation of glucose consecutively increases functional cell injury and apoptosis. Furthermore, diabetic rats developed thermal hyperalgesia and motor deficit. Activated caspase 3, cytochrome c release and Bax/Bcl-2 ratio were significantly increased in high glucose-treated PC12 cells and in spinal cord of diabetic animals. TCJ extract (60 and 80 µg/ml) attenuates high glucose-induced PC12 cells damage and apoptosis. In diabetic animals, TCJ extract at daily doses of 100 and 150 mg/kg ameliorated hyperalgesia and suppressed spinal apoptosis.

Conclusion

The data indicate that TCJ extract has neuroprotective effects against high glucose-induced neural damage. These protective effects are mediated, at least in part, through attenuation of neural apoptosis and suggest therapeutic potential of TCJ extract in amelioration of diabetic neuropathy.     

Evaluation of the antidiabetic action of Mangifera indica in mice

The leaves of Mangifera indica were assessed for antidiabetic properties using normoglycaemic, glucose-induced hyperglycaemia and streptozotocin (STZ) induced diabetic mice. The aqueous extract produced a reduction of blood glucose level in normoglycaemic and glucose-induced hyperglycaemia, but did not have any effect on streptozotocin-induced diabetic mice. The hypoglycaemic effect of the aqueous extract was compared with that of an oral dose of chlorpropamide under the same conditions. The results of this study indicate that the aqueous extract of the leaves of Mangifera indica possess hypoglycaemic activity.     

Ameliorative effects of ethanolic leaf extract of Azadirachta indica on renal histologic alterations in streptozotocin-induced diabetic rats

We studied the effect of ethanolic leaf extract of Azadirachta indica (AIE) on the microanatomy of the kidney of streptozotocin-induced diabetic rats. Thirty male Wistar rats (161-190 g) were randomly assigned to one of five treatment groups of six animals each: control, diabetic, diabetic + AIE, diabetic + metformin, AIE only. Diabetes was induced with a single intraperitoneal dose of streptozotocin (70 mg/kg body weight). AIE and metformin were administered orally for 50 days (50 d) at 500 mg/kg bw/d and 350 mg/kg bw/d, respectively. Blood glucose was estimated by glucose oxidase method; plasma urea and creatinine were assayed; and paraffin sections of the kidney were stained by periodic acid-Schiff technique. Untreated diabetic rats exhibited marked hyperglycemia. Renal histopathology of these animals showed features of diabetic nephropathy, with nodular glomerulosclerosis and vacuolation of proximal tubule cells (Armanni-Ebstein phenomenon). These feature were absent in the diabetic rats treated with AIE. Besides, plasma urea and creatinine were not significantly different from the control in this group (p > 0.05), in contrast to the untreated diabetic rats, where significant increases in these markers (p < 0.05). These findings showed that the leaf extract of Azadirachta indica ameliorates hyperglycemia and diabetic nephropathy in rats.     

神秘果提取物对链脲佐菌素诱导的糖尿病大鼠血糖及脂代谢的影响

目的:研究神秘果提取物对链脲佐菌素诱导的糖尿病大鼠血糖及脂代谢的影响。方法:采用一次性腹腔注射链脲佐菌素制备糖尿病大鼠模型,分别用神秘果提取物0.10、0.05、0.025 g/kg三个剂量灌胃给药5周,测定其血糖、糖耐量、血脂等血清生化指标。结果:连续服用神秘果提取物可以明显降低糖尿病大鼠的血糖,有效改善糖耐量水平,调节血脂含量。结论:该研究表明神秘果提取物对糖尿病大鼠有保护作用。     

Effect of the desert plant Retama raetam on glycaemia in normal and streptozotocin-induced diabetic rats

The effect of the aqueous extract of Retama raetam (RR) on blood glucose levels was investigated in fasting normal and streptozotocin-induced diabetic rats after single and repeated oral administration. The aqueous extract of RR at a dose of 20mg/kg significantly reduced the blood glucose in normal rats 6h after a single oral administration (P<0.005) and two weeks after repeated oral administration (P<0.05). This hypoglycaemic effect is more pronounced in streptozotocin (STZ) diabetic rats (P<0.001). The aqueous extract of RR had no effect on basal plasma insulin levels indicating that the underlying mechanism of RR activity is extra-pancreatic. These findings suggest that the aqueous extract of RR possess significant hypoglycaemic effect in both normal and STZ diabetic rats.     

Antidiabetic activity of Passiflora incarnata Linn. in streptozotocin-induced diabetes in mice

Ethnopharmacological relevance

The present study was designed to investigate the hypoglycemic and hypolipidemic properties of Passiflora incarnata Linn. leaves which are widely used as traditional treatment for diabetes mellitus.

Materials and methods

The methanolic extracts of leaves of Passiflora incarnata were administered orally (100 and 200 mg/kg, for 15 days) to streptozotocin-induced diabetic mice. Hypoglycemic effects, oral glucose tolerance test, change in body weight and lipid profile of diabetic mice treated with methanolic extracts were assessed and compared with normal, diabetic control and standard drug treated mice. Histological examination during 15 days of treatment was also carried out.

Results

Methanolic extract (200 mg/kg) produced a significant reduction in fasting blood glucose level in streptozotocin-induced diabetic mice. Significant differences were also observed in urine glucose level, oral glucose tolerance test, serum lipid profile and body weight of methanolic extract treated diabetic mice, when compared with diabetic, normal and standard drug treated mice. Histopathological studies of the pancreas showed comparable regeneration of the cells by extract which were earlier necrosed by streptozotocin.

Conclusion

Methanolic extract of Passiflora incarnata exhibit significant anti-hyperglycemic and hypolipidemic activities in streptozotocin-induced diabetes in mice.     

Hypoglycemic effect of Suaeda fruticosa in streptozotocin-induced diabetic rats

The purpose of this study was to examine the hypoglycemic activity of the aqueous extract of the aerial part of Suaeda fruticosa (SF) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously (i.v.) and the blood glucose changes were determined within 4 h after starting the treatment. Plasma insulin, cholesterol and triglycerides levels were also determined. The aqueous extract at a dose of 192 mg/kg produced a significant decrease in blood glucose levels in normal rats (P < 0.05), and even more in diabetic rats (P < 0.001). This hypoglycemic effect might be due to an extra-pancreatic action of the aqueous extract of SF, since that the levels of plasma insulin were unchanged between the values before and after treatment. In the other hand, the effect of the aqueous extract on the plasma cholesterol were also significant in both normal and diabetic rats (P < 0.05). But, there is no significant effect of SF on plasma triglycerides in both groups. In order to characterize the active principle(s), which could be responsible for the therapeutic effect, preliminary phytochemical analysis of the aqueous extract of the plant has been investigated.     

Effect of Vaccinium bracteatum Thunb. leaves extract on blood glucose and plasma lipid levels in streptozotocin-induced diabetic mice

Aim of the study

To investigate the hypoglycemic effects of Vaccinium bracteatum Thunb. leaves (VBTL) extract in streptozotocin-induced diabetic mice.

Materials and methods

After administration of VBTL extract for 4 weeks, the body weight, organ weight, blood glucose (BG), insulin and plasma lipid levels of streptozotocin-induced diabetic mice were measured.

Results

Body weights of diabetic mice treated with VBTL extract were partly recovered. The BG levels of AEG (diabetic mice treated with VBTL aqueous extract) were reduced to 91.52 and 85.82% at week 2 and week 4, respectively (P < 0.05), while those of EEG (diabetic mice treated with VBTL ethanolic extract) were reduced slightly (P > 0.05). The insulin levels of AEG and EEG were obviously higher (P < 0.05) than those of MC (diabetic mice in model control group). Comparing with MC, AEG and EEG had significantly lower (P < 0.05) TC or TG levels and similar HDL-cholesterol or LDL-cholesterol levels. In comparison with non-diabetic control mice, AEG had similar plasma lipid levels except higher LDL-cholesterol level, while EEG had higher TC, TG and LDL-cholesterol levels and lower HDL-cholesterol levels.

Conclusions

Both aqueous and ethanolic extract of VBTL possess a potential hypoglycemic effect in streptozotocin-induced diabetic mice.     

Hypoglycaemic effect of spergularia purpurea in normal and streptozotocin-induced diabetic rats

Single and repeated oral administration of the water extracts of Spergularia purpurea (SP) at a dose of 10 mg/kg were tested on hypoglycaemic activity in normal and streptozotocin-induced diabetic rats. In normal rats, the water extract of SP decreased significantly the plasma glucose levels 4 h after single oral administration (P<0.01), and one week after repeated oral administration (P<0.05). A significant decrease of plasma glucose levels was observed 6 h after a single oral administration of the water extract of S. purpurea in severe hyperglycaemic rats (n=6) from 22.78+/-0.60 to 11.21+/-0.49 mmol/l (P<0.001). On other hand, water extract of S. purpurea normalised plasma glucose levels after two weeks of repeated oral administration in diabetic rats; 24.05+/-1.16 versus 7.18+/-0.51 mmol/l (P<0.001) at the start and 2 weeks after water extract administration, respectively. We conclude that the water extract of SP induces hypoglycaemic activity when administered orally in normal and STZ diabetic rats. In order to determine the active principle (s) responsible of the hypoglycaemic effect, preliminary phytochemical analysis of the water extract has been investigated.     

Hypoglycaemic activity and molecular mechanisms of Caesalpinia ferrea Martius bark extract on streptozotocin-induced diabetes in Wistar rats

Ethnopharmacological relevance

The tea from the stem bark of Caesalpinia ferrea Martius (Leguminosae) has been popularly used in the treatment of diabetes in Brazil.

Aim of the study

To investigate the hypoglycaemic properties and to elucidate the mechanisms by which the aqueous extract of the stem bark of Caesalpinia ferrea reduces blood glucose levels in streptozotocin-induced diabetic rats via the enzymatic pathways of protein kinase B (PKB/Akt), AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC).

Materials and methods

The aqueous extract of the stem bark of Caesalpinia ferrea (300 and 450 mg/kg/day), vehicle and metformin (500 mg/kg/day) were administered orally to STZ-diabetic rats (n = 7/group) for 4 weeks. Changes in body weight, food and water intake, fasting glucose levels and oral glucose tolerance were evaluated. Phosphorylation (P) and the expression of Akt, AMPK and ACC in the liver and skeletal muscle were determined using Western blot.

Results

The aqueous extract of the stem bark of Caesalpinia ferrea reduced blood glucose levels and improved the metabolic state of the animals. P-Akt was increased in the liver and skeletal muscle of the treated animals, P-AMPK was reduced only in the skeletal muscle of these animals and P-ACC was reduced in both when compared with untreated rats.

Conclusion

The results indicate that the aqueous extract of the stem bark of Caesalpinia ferrea has hypoglycaemic properties and possibly acts to regulate glucose uptake in liver and muscles by way of Akt activation, restoring the intracellular energy balance confirmed by inhibition of AMPK activation.     

Cholesterol and triglycerides lowering activities of caraway fruits in normal and streptozotocin diabetic rats

The purpose of this study was to examine the effect of single and repeated oral administration of the aqueous extract of Carum carvi L. fruits at a dose of (20mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats (STZ). After a single oral administration, Carum carvi extract produced a significant decrease on triglycerides levels in normal rats (p<0.05). In STZ diabetic rats, cholesterol levels were decreased significantly 6h after Carum carvi treatment (p<0.05). On the other hand, repeated oral administration of Carum carvi extract exhibited a significant hypotriglyceridemic and hypocholesterolemic activities in both normal (p<0.01 and <0.001 respectively) and STZ diabetic rats (p<0.001) 15 days after Carum carvi treatment. We conclude that the aqueous extract of Carum carvi (20mg/kg) exhibits a potent lipid lowering activity in both normal and severe hyperglycemic rats after repeated oral administration of Carum carvi aqueous extract.     

Hypoglycaemic effect of water extracts of Aegle marmelos fruits in streptozotocin diabetic rats

Aegle marmelos Corr. (Rutaceae) is widely used in Indian Ayurvedic medicine for the treatment of diabetes mellitus. The hypoglycaemic effect of the water extract of the fruits of Aegle marmelos was examined in streptozotocin-induced diabetic Wistar rats. Oral administration of the water extract (125 and 250mgkg(-1)) twice a day for 4 weeks resulted in significant reductions in blood glucose, plasma thiobarbituric acid reactive substances, hydroperoxides, ceruloplasmin and alpha-tocopherol and a significant elevation in plasma reduced glutathione and Vitamin C in diabetic rats. The effect of the extract at a dose of 250mgkg(-1) was more effective than glibenclamide in restoring the values of these parameters. The results of this study clearly shows the hypoglycaemic activity of the fruit extract.     

Antidiabetic effect of Olea europaea L. in normal and diabetic rats

The antidiabetic effect of an alcohol extract of olive (Olea europaea L.) leaves was investigated in normal and streptozotocin-induced diabetic rats. The oral administration of the olive leaves extract (0.1, 0.25 and 0.5 g/kg body wt) for 14 days significantly decreased the serum glucose, total cholesterol, triglycerides, urea, uric acid, creatinine, aspartate amino transferase (AST) and alanine amino transferase (ALT) while it increased the serum insulin in diabetic rats but not in normal rats (p < 0.05). A comparison was made between the action of olive leaves extract and glibenclamide (600 microg/kg), a known antidiabetic drug. The antidiabetic effect of the extract was more effective than that observed with glibenclamide.     

Hypoglycaemic effect of Opuntia lindheimeri Englem in a diabetic pig model

The hypoglycaemic activity of Opuntia lindheimeri Englem. was investigated in non-diabetic (control pigs) and streptozotocin-induced diabetic pigs using an enteral (oral) route of administration. Following the administration of O. lindheimeri extract (0, 250 or 500 mg/kg body weight), blood glucose concentrations in control pigs fluctuated around initial baseline concentrations, but were not consistently affected by either the dose of O. lindheimeri or by the time following administration. In contrast, administration of O. lindheimeri extract to STZ-treated pigs resulted in both a dose- (p < 0.001) and time-dependent (p < 0.001) decrease in blood glucose concentrations. The hypoglycaemic effect of the extract was apparent within 1 h of administration, with maximal effects occurring at 4 h after administration. These results confirm the hypoglycaemic effect of O. lindheimeri extract in a diabetic pig model. In addition, given the physiological similarities of the pig to humans, this model will be of tremendous use in assessing the long-term effects of Opuntia administration on the secondary problems associated with diabetes.     

Effects of Orthosiphon stamineus aqueous extract on plasma glucose concentration and lipid profile in normal and streptozotocin-induced diabetic rats

The objective of this study was to investigate the effects of Orthosiphon stamineus Benth. aqueous extract on plasma glucose concentration and lipid profile in normal and streptozotocin-induced diabetic rats. The chemical screening of the extract showed phenolic compound and flavonoid content were 13.24+/-0.33 mg/g and 1.73+/-0.14 microg/g, respectively. In oral glucose tolerance test, the extract (0.2-1.0 g/kg) significantly decreased plasma glucose concentration in a dose-dependent manner in both normal and diabetic rats. The extract at 1.0 g/kg was most effective in decreasing plasma glucose concentrations and the response was closed to the result of glibenclamide (5 mg/kg). After repeated daily oral administrations of the extract (0.5 g/kg) for 14 days, the extract significantly reduced plasma glucose concentration in diabetic rats at days 7 and 14. By the end of the study, plasma triglyceride concentration was lower in the extract-treated diabetic rats than untreated ones. Furthermore, plasma HDL-cholesterol concentration was significantly increased in diabetic rats treated with the extract. In perfused rat pancreas, the extract did not increase insulin secretion in the presence of 5.5 mM glucose, but 100 microg/ml extract potentiated glucose-induced insulin secretion. Our findings suggested that Orthosiphon stamineus aqueous extract is effective for alleviating hyperglycemia and improving lipid profile in diabetic rats.