Evaluation of antidiabetic, antioxidant and vasoprotective effects of Posidonia oceanica extract

The aim of this study is to evaluate antidiabetic, antioxidant and vasoprotective effects of Posidonia oceanica extract (POE) in alloxan diabetic rats. Posidonia oceanica (L) Delile (Posidoniaceae), is a widely allocated phanerogam in Mediterranean and Aegean Sea. Up to date, no published data relevant to use of the plant in traditional medicine are available. However, decoction of the leaves has been quoted to be used as a remedy for diabetes mellitus and hypertension by villagers living by the sea coast of Western Anatolia. Oral administration of extract for 15 days (50, 150, and 250 mg/kg b.wt.) resulted in a dose-dependent decrease in blood glucose. Relaxant responses to acetylcholine (ACh) in diabetic thoracic aorta were restored by POE treatment (50, 150, and 250 mg/kg b.wt.). POE also attenuated the augmented phenylephrine (PE) and serotonin (5-HT) contractions. At concentration levels of 150 and 250 mg/kg b.wt., POE exerted a protective effect on the significantly decreased levels of antioxidants namely, glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase and nitric oxide (NO). POE (50mg/kg b.wt.) produced no effect on alloxan-induced alterations in the antioxidant status while possessing glucose lowering and vasoprotective activities. Furthermore, liver and kidney function markers, leucocyte counts, body weight and liver glycogen content remained unchanged at dose level of 50mg/kg b.wt., when compared with diabetic control group. These results suggest that antidiabetic and vasoprotective effects of POE may be unrelated to its antioxidant properties.     

Anti-diabetic activity of medicinal plants and its relationship with their antioxidant property

Methanolic extract (75%) of Terminalia chebula, Terminalia belerica, Emblica officinalis and their combination named 'Triphala' (equal proportion of above three plant extracts) are being used extensively in Indian system of medicine. They were found to inhibit lipid peroxide formation and to scavenge hydroxyl and superoxide radicals in vitro. The concentration of plant extracts that inhibited 50% of lipid peroxidation induced with Fe(2+)/ascorbate were food to be 85.5, 27, 74 and 69 micro g/ml, respectively. The concentration needed for the inhibition of hydoxyl radical scavenging were 165, 71, 155.5 and 151 micro g/ml, and that for superoxide scavenging activity were found to be 20.5, 40.5, 6.5 and 12.5 micro g/ml, respectively. Oral administration of the extracts (100 mg/kg body weight) reduced the blood sugar level in normal and in alloxan (120 mg/kg) diabetic rats significantly within 4 h. Continued, daily administration of the drug produced a sustained effect.     

Anti-diabetic activity of Picrorrhiza kurroa extract

An alcoholic extract of Picrorrhiza kurroa was found to lower blood glucose in basal conditions and after a heavy glucose load in normal rats. Maximum reduction in serum glucose was observed after 2 h at a dose level of 75 mg extract/kg of body weight. P. kurroa extract was also found to reduce the increase of blood sugar in alloxan-induced diabetic rats (43% at 75 mg/kg body weight and 60% at 150 mg/kg body weight). Chronic administration of the extract significantly reduced the blood sugar in alloxan-induced diabetic rats for several days (10 days). The extract was also found to reduce the increased blood urea nitrogen and serum lipid peroxides in alloxan-induced diabetic animals and to inhibit the body weight reduction and leukopenia induced by alloxan administration. These results indicate that P. kurroa extracts are able to ameliorate biochemical damages induced by alloxan in diabetic rats.     

Effects of berberine on diabetes induced by alloxan and a high-fat/high-cholesterol diet in rats

Berberine is the major active constituent of Rhizoma coptidis. The present study was carried out to investigate the effect of berberine on diabetes in rats and its possible mechanisms. Diabetes was induced by tail vein injection with alloxan in Wistar rats. The amount of alloxan administered was 55 mg/kg. Diabetic rats were fed with a high-cholesterol diet. The fasting blood glucose, total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDL-c), high density lipoprotein-cholesterol (HDL-c), nitric oxide (NO) levels in serum and malondialdehyde (MDA),superoxide dismutase (SOD),glutathione peroxidase (GSH-px) contents in heart tissue were assayed by spectrophotometry. Pancreas samples collected after 3 weeks of alloxan treatment were stained with hematoxylin-eosin (HE) and examined under a light microscope, and scored. Intragastric administration of berberine (100 and 200 mg/kg) significantly decreased fasting blood glucose levels, serum content of TC, TG, LDL-c, and effectively increased HDL-c, NO level in diabetic rats. Furthermore, berberine treatment significantly blocked the increase of MDA, increased SOD and GSH-px levels in diabetic rats. Histopathological scores showed that berberine had restored the damage of pancreas tissues in rats with diabetes mellitus. The results showed berberine significantly inhibited the progression of diabetes induced by alloxan, and the inhibitory effect of berberine on diabetes might be associated with its hypoglycemic effect, modulating lipids metabolic effects and its ability to scavenge free radical.     

Effect of Cassia auriculata Linn. on serum glucose level,glucose utilization by isolated rat hemidiaphragm

An aqueous leaf extract of Cassia auriculata (C. auriculata) was found to lower the serum glucose level in normal rats. Maximum reduction in serum glucose level was observed after 4 h at a dose levels of 100, 200, 400 mg/kg body weight of the extract. In normal rats the serum glucose level reduction at 4th h was 23% by 100 mg/kg body weight and 31% by 200 mg/kg body weight. In alloxan-induced diabetic rats, chronic administration of the extract significantly reduced the serum glucose level from third day to till the end of the experiment. The extract was also found to inhibit the body weight reduction induced by alloxan administration. Glucose uptake and glycogen deposition studies suggest that C. auriculata leaf extract probably has no direct insulin like effect which can enhance the peripheral utilization of glucose.     

Anti-diabetic activity of alcoholic extract of Aerva lanata (L.) Juss. ex Schultes in rats

Aerva lanata (L.) Juss. ex Schultes commonly known as ‘Sunny khur’ is widely used in Indian folk medicine for the treatment of Diabetes mellitus. This study was undertaken to evaluate the effect of an alcoholic extract of A. lanata (AAL) on blood glucose and other biochemical parameters in alloxan-induced diabetic rats. AAL was found to reduce the increase of blood sugar in alloxan-induced diabetic rats (42% at 375 mg/kg and 48% at 500 mg/kg body weight). Chronic administration of AAL significantly (P<0.001) reduced the blood sugar of alloxan induced diabetic rats for 2 weeks. Also the extract prevented a decrease in body weight and reduced the increased lipid peroxides in alloxan induced diabetic rats. These results suggest that the AAL posseses anti-diabetic activity and is able to ameliorate biochemical damages in alloxan induced diabetic rats.     

荞麦蜂花粉多糖对糖尿病大鼠血糖、血脂的影响

目的:观察荞麦蜂花粉多糖对四氧嘧啶(ALX)性糖尿病大鼠血糖、血脂的影响。方法:用ALX建立糖尿病大鼠模型,分别用荞麦蜂花粉多糖150mg/(kg.d)、300mg/(kg.d)及阳性对照药苯乙双胍350mg/(kg.d)灌胃治疗,正常对照组及糖尿病模型对照组则给等容积生理盐水。连续给药14d后,分别测定各组大鼠血糖、血脂。结果:荞麦蜂花粉多糖150mg/(kg.d)、300mg/(kg.d)能明显降低ALX所致糖尿病大鼠高血糖,与糖尿病模型对照组相比,P<0.01。同时,相同剂量的荞麦蜂花粉多糖还能明显降低ALX性糖尿病大鼠血清TG(P<0.05)、TC、LDL-C(P<0.01)。另外,荞麦蜂花粉多糖300mg/(kg.d)还能使糖尿病大鼠血清HDL-C显著回升(P<0.05)。但荞麦蜂花粉多糖150mg/(kg.d)对HDL-C则无明显影响(P>0.05)。结论:荞麦蜂花粉多糖能降低ALX性糖尿病大鼠高血糖、血脂,提示荞麦蜂花粉多糖对糖尿病的防治具有一定的应用价值。     

Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region

The effect of an aqueous extract of Origanum vulgare (OV) leaves on blood glucose levels was investigated in normal and streptozotocin (STZ) diabetic rats. In normal rats, the blood glucose levels were slightly decreased 6 h after a single oral administration (P<0.05) as well as 15 days after once daily repeated oral administration of aqueous OV extract (P<0.05) (20 mg/kg). After a single dose or 15 daily doses, oral administration of the aqueous extract (20 mg/kg) produced a significant decrease on blood glucose levels in STZ diabetic rats (P<0.001). In STZ rats, the blood glucose levels were normalised from the fourth day after daily repeated oral administration of aqueous OV extract (20 mg/kg) (P<0.001). However, this effect was less pronounced 2 weeks after daily repeated oral administration of OV extract. In addition, no changes were observed in basal plasma insulin concentrations after treatment in either normal or STZ diabetic rats indicating that the aqueous OV extract acted without changing insulin secretion. We conclude that an aqueous extract of OV exhibits an anti-hyperglycaemic activity in STZ rats without affecting basal plasma insulin concentrations.     

哈普片降血糖作用的实验研究

目的：研究哈普片对高血糖小鼠和正常动物的降血糖作用及其对血清胰岛素的影响。方法：通过静脉注射四氧嘧啶建立高血糖小鼠模型,将哈普片制成浸膏给予受试动物灌胃;用酶法测定血糖,竞争放射免疫分析测定血清胰岛素;数据经t检验统计处理。结果：哈普片浸膏ig 14d可使四氧嘧啶高血糖小鼠血糖明显降低（P＜0．05,P＜0．01）,同时使相应的血清胰岛素显著升高（P＜0．01）,而同样剂量对正常小鼠无降糖作用;哈普片浸膏ig 90d可使正常大鼠血糖显著降低（P＜0．01,P＜0．001）,用8．4g生药／kg剂量ig 14d对高血糖小鼠与正常小鼠的糖耐量均有影响,明显增强由葡萄糖刺激引起的胰岛分泌功能。结论：哈普片口服对实验性高血糖小鼠有降糖作用,并能促进其血清胰岛素的分泌;长期服用可降低正常大鼠血糖。     

紫苏总黄酮提取物对四氧嘧啶致糖尿病小鼠糖脂代谢及抗氧化水平的影响

目的:观察紫苏总黄酮提取物(TFP)对四氧嘧啶致糖尿病小鼠血糖、血脂及血清过氧化物歧化酶(SOD)、丙二醛(MDA)的调节作用。方法:采用四氧嘧啶(140mg/kg)腹腔注射建立糖尿病小鼠模型,并灌胃给不同剂量的TFP,给药28d,末次给药后尾部采血测定血糖值;眼球取血分离血清测定血脂指标及抗氧化指标。结果:各组血糖、血脂水平及血清MDA含量均较正常组明显升高,二甲双胍、TFP治疗组均较模型组显著下降(P<0.01)。各组血清SOD活性均较正常组明显降低,二甲双胍、TFP治疗组均较模型组显著升高(P<0.01)。结论:TFP对四氧嘧啶导致的糖尿病小鼠有明显的治疗作用,其降糖机制可能与其提高糖尿病小鼠抗氧化能力及改善血脂、血糖水平有关。     

The hypoglycaemic and antihyperglycaemic effect of citrullus colocynthis fruit aqueous extract in normal and alloxan diabetic rabbits

Effects of the aqueous, glycosidic, alkaloidal and saponin extracts of the rind of Citrullus colocynthis on the plasma glucose levels were investigated in normal rabbits, while the effects of saponin extract on the fasting plasma glucose levels were studied in alloxan induced diabetic rabbits. In normal rabbits, oral administration of aqueous extract (300 mg/kg) produced significant reduction in plasma glucose after 1 h and highly significant after 2,3 and 6 h. Phytochemical screening revealed that the rind of C. colocynthis and its aqueous extract contains tertiary and quaternary alkaloids, glycoside and saponin components. The hypoglycaemic effects of these components given orally at a dose (50 mg/kg) were studied in normoglycaemic rabbits. Result showed that the alkaloidal extract did not significantly lower the blood glucose levels from 132 mg/100 ml at 0 h to 120 mg/100 ml after 6 h, while the glycosidic extract significantly lowered the fasting glucose levels after 2 and 3 h and highly significant after 6 h. The effect was more pronounced with saponin extract, the saponin significantly lowered the fasting glucose levels after 1 and 2 h and highly significant (P<0.001) after 3 and 6 h. Graded doses (10, 15 and 20 mg/kg) of saponin extract, when given orally to alloxan diabetic rabbits, produced a significant reduction of plasma glucose concentration. These results suggest that the aqueous extract of the rind of C. colocynthis possesses a hypoglycaemic effect and its hypoglycaemic action could be attributed for more extent to the presence of saponin in addition to the presence of glycosidic components.     

Effects of wild ginseng (Panax ginseng C.A. Meyer) leaves on lipid peroxidation levels and antioxidant enzyme activities in streptozotocin diabetic rats

The aim of this study was to examine the possible antioxidant activities of wild Panax ginseng leaf extract intake in streptozotocin (STZ)-induced diabetic rats (WGLE). Initial blood glucose levels increased abruptly after streptozotocin injection. After 4 weeks of WGLE supplementation, blood glucose levels were lower in animals fed 40 mg/kg (266 mg/dL) and 200 mg/kg (239 mg/dL) than those in no-WGLE fed diabetic rats (464 mg/dL). The concentration of blood TBARS, which are considered the main products of glucose oxidation in blood, was also lowered by WGLE supplementation. These results indicate that WGLE supplementation is involved in suppressing a sudden increase in blood glucose levels and a consequent decrease in TBARS levels in diabetic rats. TBARS levels in the liver, kidney and spleen of WGLE-fed diabetic groups were also significantly lower than in the control diabetic group indicating that oral administration of WGLE effectively suppresses lipid peroxidation that occurs in the organs of diabetic rats. Antioxidant activities of WGLE supplementation further extend in suppressing activities of antioxidant related enzymes, such as glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD), in organs of diabetic rats. These results confirm the effectiveness of WGLE supplementation in detoxifying free radicals that are produced excessively in diabetic-induced complications.     

Evaluation of anti-hyperglycemic and hypoglycemic effect of Trigonella foenum-graecum Linn, Ocimum sanctum Linn and Pterocarpus marsupium Linn in normal and alloxanized diabetic rats.

The hypoglycemic effect of the aqueous (Aq) extract of the bark of Pterocarpus marsupium (PM) and alcoholic (Alc) extract of seeds of Trigonella foenum-graecum (FG) and leaves of Ocimum sanctum (OS) was investigated in both normal and alloxan-induced diabetic rats. The Aq extract of PM (1 g/kg PO) significantly (P<0.001) reduced the blood sugar levels from 72.32+/-5.62 to 61.35+/-1.2 mg% 2 h after oral administration of the extract and also significantly lowered the blood glucose in alloxan diabetic rats from 202.91+/-5.44 to 85.22+/-11.28 mg% 21 days after daily oral administration of the extract (P<0.001). Similarly, reduction was seen with Alc extract of FG (74.33+/-4.77 to 60.56+/-1.9 in normal rats and 201.25+/-7.69 to 121.25+/-6.25 in diabetic rats) (P<0.001) and OS (204.48+/-11.0 to 131.43+/-7.86 in normal rats and 73.54+/-3.7 to 61.44+/-2.3 in diabetic rats) (P<0.001). In addition, the extract also showed a favorable effect on glucose disposition in glucose fed hyperglycemic rats.     

Antidiabetic and antihyperlipidaemic effect of alcoholic Syzigium cumini seeds in alloxan induced diabetic albino rats

Syzigium cumini, commonly known as 'jamun', is widely used in different parts of India for the treatment of diabetes mellitus. The present study was designed to evaluate the antidiabetic and antihyperlipidaemic effect of an alcoholic extract of Syzigium cumini seeds (JSEt) in alloxan diabetic rats. Diabetes was induced by single intraperitoneal injection of alloxan (150 mg kg(-1) body weight). Oral administration of alcoholic JSEt to diabetic rats at a dose of 100 mg kg(-1) body weight resulted in a significant reduction in blood glucose and urine sugar and lipids in serum and tissues in alloxan diabetic rats. The extract also increases total haemoglobin. The extract brought back all the parameters to normal levels. The effect of alcoholic JSEt was similar to that of insulin. Thus, our investigation clearly shows that alcoholic JSEt has both antidiabetic and antihyperlipidaemic effects.     

螺旋藻多糖和鼠尾藻多糖对四氧嘧啶致糖尿病大鼠血管的保护作用

目的研究螺旋藻粗提多糖和鼠尾藻粗提多糖联合使用对四氧嘧啶糖尿病大鼠血管的保护作用。方法2种多糖以1∶1混合,分别以123,368,1103mg·kg^-1灌胃给予四氧嘧啶致高血糖大鼠高、中、低各组。连续给药6周后,分别测定各组大鼠的血糖、TC,HDLC,TG,NO,ET。并取各鼠胸主动脉测定其对去甲肾上腺素(NE)和乙酰胆碱(ACh)舒缩反应的变化。结果混合多糖能降低ALX性糖尿病大鼠的血糖与血清TC,TG,NO,ET,升高血清HDLC。ALX模型大鼠主动脉对NE的收缩反应显著增强,对ACh舒张反应显著减弱。混合多糖能显著降低NE的收缩反应,改善糖尿病大鼠血管内皮依赖的舒缩反应功能。结论2种多糖联合使用能降低血糖并对血管有一定的保护作用。     

Ameliorative effects of pycnogenol on carbon tetrachloride-induced hepatic oxidative damage in rats

This study evaluated the putative antioxidant activity of Pycnogenol (PYC) against CCl4-induced hepatic oxidative damage in Sprague-Dawley rats. A single oral dose of CCl4 (1.25 mL/kg) produced significantly increased levels of serum aminotransferase (AST) and alanine aminotransferase (ALT) activities. In addition, increased malondialdehyde (MDA) concentration, reduced glutathione (GSH) content, and decreased catalase, superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities were observed in the hepatic tissues. However, concomitant administration with PYC (10 or 20 mg/kg) significantly improved CCl4-induced hepatic injury, as evidenced by the decline of serum AST and ALT activities in a dose dependent manner. Moreover, PYC reduced MDA concentration and increased GSH levels and catalase, SOD and GST activities in hepatic tissues, indicating that concomitant administration with PYC efficiently prevent the CCl4-induced oxidative damage in rats. The free radical scavenging assay showed that PYC has a dose-dependent scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. These results indicate that PYC has an antioxidant effect against CCl4-induced hepatic oxidative damage and is useful as a hepatoprotective agent against various liver diseases induced by oxidative stress.     

Antihyperglycemic and hypoglycemic effect of Aporosa lindleyana in normal and alloxan induced diabetic rats

The hypoglycemic effect of aqueous and alcoholic extracts of root of Aporosa lindleyana was investigated in both normal and alloxan induced diabetic rats. The blood glucose levels were measured at 0, 1, 2 and 3 h after the treatment. The aqueous and alcoholic extracts of A. lindleyana (100 mg/kg) reduced the blood glucose of normal rat from 80.4+/-2.7 to 69.8+/-2.0 mg% and 82.6+/-1.9 to 70.8+/-3.2 mg%, respectively 3 h after oral administration of the extract (P < 0.001) and also significantly lowered blood glucose level in alloxan induced diabetic rat from 306+/-3.37 to 160+/-2.46 and 328+/-4.15 to 152+/-3.86 mg%, respectively 3 h after oral administration of the extract (P < 0.001). The antihyperglycemic activity of A. lindleyana was compared with tolbutamide, an oral hypoglycemic agent.     

Antidiabetic and antioxidant effects of oleanolic acid from Ligustrum lucidum Ait in alloxan‐induced diabetic rats

The present study evaluated the antidiabetic and antioxidant effects of oleanolic acid (OA) from Ligustrum lucidum Ait (LLA) in alloxan‐induced diabetic rats. OA in the alloxan‐induced diabetic rats showed significant hypoglycemic activity by lowering blood glucose (at doses of 60 and 100 mg/kg for 40 days). The levels of serum total cholesterol (TC), triglycerides (TG) and low‐density lipoprotein cholesterol (LDL‐c) in the OA‐treated diabetic rats were lower, and the high‐density lipoprotein cholesterol (HDL‐c) level was higher than in the control diabetic rats. A significant reduction in the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels of diabetic rats following OA treatment was also observed. Furthermore, OA treatment decreased the malondialdehyde (MDA) level, but increased superoxide dismutase (SOD) and glutathione peroxidase (GSH‐px) activities of the liver and kidney in diabetic rats. These results indicate that OA could protect the liver function avoiding alloxan‐induced damage; OA had hypoglycemic, hypolipidemic and antioxidant efficacy in the diabetic rats. The antioxidant ability of OA might be one of the mechanisms of its hypoglycemic and hypolipidemic effects. Copyright © 2009 John Wiley & Sons, Ltd.     

The effect of Anethum graveolens L. (dill) on corticosteroid induced diabetes mellitus: involvement of thyroid hormones

An investigation was made to evaluate the role of Anethum graveolens L. (dill) leaf extract in the regulation of corticosteroid-induced type 2 diabetes mellitus in female rats. In dexamethasone-treated animals (1 mg/kg for 22 days) an increase in serum concentration of insulin and glucose and in hepatic lipid peroxidation (LPO) was observed. However, there was a decrease in serum concentration of thyroid hormones and in the endogenous antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) in liver. In animals treated with an equivalent amount of dexamethasone for a similar period (22 days) when received the leaf extract (100 mg/kg b.wt/d.) for last 15 days a decrease in the concentration of both serum glucose and insulin was observed, indicating the potential of the plant extract in the regulation of corticosteroid-induced diabetes. Dexamethasone-induced alterations in the levels of thyroid hormones as well as in hepatic LPO, SOD, CAT and GSH were also reversed by the plant extract.     

Mitigation of thyroxine-induced hyperglycaemia by two plant extracts

Extracts of Trigonella foenum-graecum (TFG) seed and Allium sativum (AS) bulb were evaluated for their efficacy to ameliorate l-thyroxine (l-T4) induced hyperglycaemia in rats. Simultaneously, the serum cholesterol concentration, a supporting parameter for thyroid function, was also estimated. Thyroxine treatment in rats (300 microg/kg b. wt./day) increased the levels of both the thyroid hormones, namely thyroxine (T4) and tri-iodothyronine (T3) with a concomitant elevation in serum glucose concentration and a reduction in serum cholesterol level. Administration of TFG (220 mg/kg/day) and AS (500 mg/kg/day) extracts in hyperthyroid animals decreased the serum glucose concentration as well as the serum thyroid hormones. For comparison, propyl thiouracil (PTU), an antithyroid compound, was used as the standard at a daily dose of 10 mg/kg. The reductions in serum glucose and thyroid hormone concentrations in the plant extract treated groups were comparable to that in PTU treated animals. Our findings indicate that TFG seed and AS bulb extracts may prove to be effective in the treatment of thyroxine-induced hyperglycaemia.