Antidiabetic activity of hydro-ethanolic extract of Cyperus rotundus in alloxan induced diabetes in rats

In light of the traditional claim of Cyperus rotundus in the treatment of diabetes, investigations were carried out to evaluate its effect on alloxan induced hyperglycemia in rats. Oral daily administration of 500 mg/kg of the extract (once a day for seven consecutive days) significantly lowered the blood glucose levels. This antihyperglycemic activity can be attributed to its antioxidant activity as it showed the strong DPPH radical scavenging action in vitro.     

Hypoglycemic and antidiabetic activities on the stem bark aqueous and ethanol extracts of Musanga cecropioides in normal and alloxan-induced diabetic rats

Daily oral administration of the aqueous and ethanolic extracts of Musanga cecropioides stem bark in normal and diabetic rats at doses of 250, 500 and 1000 mg/kg/day, for 14 days significantly lowered the fasting plasma glucose levels in normal and alloxan-induced diabetic rats in dose-dependent fashion. The ethanol extract induced more significant antidiabetic effect than the aqueous extract.     

Potential insulin secretagogue effects of isovitexin and swertisin isolated from Wilbrandia ebracteata roots in non-diabetic rats

The antihyperglycemic effect and mechanism of action of extracts, fractions and compounds from Wilbrandia ebracteata was studied. The crude extract reduced the glycemia, increased glycogen content and serum insulin in hyperglycemic rats. Also, a significant effect was observed with the n-butanol and metanol subfraction. However, the antihyperglycemic effect of the n-butanol fraction was not observed in diabetic rats. The C-glycosylflavones isovitexin and swertisin showed a strong antihyperglycemic action compared with the extracts and fractions. These results show that the extracts, fractions, and isolated C-glycosylflavones have an antihyperglycemic action that was reinforced by the stimulation on in vivo insulin secretion.     

Antidiabetic and antihyperlipemic effects of Clemeo felina

Petroleum ether and benzene extracts of Clemeo felina, given orally at doses of 300 mg kg(-1) day(-1) for 30 days, were found to be antidiabetic and antihyperlipemic on alloxan diabetic rats. Moreover, a significant decrease in the activities of serum enzymes like alkaline phosphatase, acid phosphatase and HMGCoA reductase activity in the liver was observed. However, treatment of rats with the extracts as well as standard antidiabetic drugs increased liver hexakinase activity and serum LDH activity.     

Antihyperglycemic effects of Japanese maple Acer amoenum leaf extract and its constituent corilagin

The antihyperglycemic effects of the leaves of Acer amoenum and purification and identification of an active compound were investigated. In screening experiments for α-glucosidase inhibitory activity, methanolic extracts of A. amoenum leaves showed potent inhibitory action. This extract showed antihyperglycemic effects in sucrose-loaded mice. Fractionation of the crude extract gave the active compound corilagin [β-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-d-glucose] by spectroscopic analysis. This is the first report about the possibility of novel utilization of the Japanese maple tree as a source of compounds for prevention or treatment of diabetes mellitus.     

Antiobesity and lipid lowering effects of Murraya koenigii (L.) Spreng leaves extracts and mahanimbine on high fat diet induced obese rats

The dichloromethane (MKD) and ethyl acetate (MKE) extracts of Murraya koenigii leaves significantly reduced the body weight gain, plasma total cholesterol (TC) and triglyceride (TG) levels significantly when given orally at a dose of 300 mg/kg/day to the high fat diet (HFD) induced obese rats for 2 weeks. The observed antiobesity and antihyperlipidemic activities of these extract are correlated with the carbazole alkaloids present in them. Mahanimbine (1) when given orally (30 mg/kg/day) also significantly lowered the body weight gain as well as plasma TC and TG levels. These findings demonstrate the excellent pharmacological potential of mahanimbine to prevent obesity.     

Antihyperglycemic activity of Caralluma attenuata

Extracts of Caralluma attenuata are screened for their antihyperglycemic activity. Ethanol, chloroform and butanol extracts were tested on glucose loaded and alloxan-induced diabetic rats. In both tests, the butanol extract, at the oral dose of 250 mg/kg, has shown statistically significant and considerable antihyperglycemic activity.     

Cytotoxicity and antihyperglycemic effect of minor constituents from Rhizoma Coptis in HepG2 cells

Generally, berberine, coptisine, palmatine, and jatrorrhizine were considered as the main bio-active compounds in Rhizoma Coptis (RC). Little attention was paid to investigate the pharmacological activity of minor constituents in RC. The present study was designed to separate the minor compounds, and the cytotoxicity and antihyperglycemic effect of these compounds in HepG2 cells were also studied. Palmatine (1), berberine (2), coptisine (3), epiberberine (4), columbamine (5), and jatrorrhizine (6) from RC ethanol extract were isolated by high speed counter current chromatography (HSCCC) in one run. The remaining fraction (about 50% of extract in HSCCC) was further isolated by traditional column chromatography methods to yield magnoflorine (7), ferulic acid (8), and choline (9). Another four alkaloids, namely groenlandicine (10), berberrubine (11), oxyberberine (12), 8-oxo-coptisine (13), also were obtained from CHCl₃ extracts. Especially, choline was first isolated from RC. Cell assay indicated that the minor fractions excluding compounds 1-6 showed obvious glucose lowering activity. In addition, the minor monomers also exhibited moderate glucose lowering activity. The combination of berberine and ferulic acid showed synergistic effect on antihyperglycemic. The combination of alkaloids 1-6 was same so. All compounds had different cytotoxicity in HepG2 cells within the test concentration. Of them, berberrubine showed the strongest cytotoxicity. The results suggested that combined action of variety constituents contributed to the antihyperglycemic effets and low cytotoxicity of RC extract in HepG2 cells.     

Effect of Helicteres isora root extracts on glucose tolerance in glucose-induced hyperglycemic rats

The ethanol, ethyl acetate and butanol extracts of Helicteres isora root showed significant oral hypoglycemic activity on glucose loaded rats at a dose of 250 mg/kg. The butanol extract showed maximum antihyperglycemic activity and effect being comparable to that of glibenclamide.     

Antioxidant effects of Gongronema latifolium in hepatocytes of rat models of non-insulin dependent diabetes mellitus

Gongronema latifolium is a rainforest plant, which has been traditionally used in the South Eastern part of Nigeria for the management of diabetes. The effects of oral administration of aqueous and ethanolic G. latifolium leaf extracts for 2 weeks on streptozotocin-induced diabetic rats were investigated. Both extracts were shown to significantly increase the activity of superoxide dismutase and the level of reduced glutathione. The aqueous extract further increased the activity of glutathione reductase while the ethanolic extract caused a significant increase in the activity of glutathione peroxidase and glucose-6-phosphate dehydrogenase and a significant decrease in lipid peroxidation. These results suggest that the extracts from G. latifolium leaves could exert their antidiabetic activities through their antioxidant properties.     

Inhibition of 11β-hydroxysteroid dehydrogenase type 1 by plant extracts used as traditional antidiabetic medicines

Elevated glucocorticoids are a key risk factor for metabolic diseases, and the glucocorticoid-activating enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) represents a promising therapeutic target. We measured the potential of six traditional antidiabetic medicinal plants extracts to inhibit 11β-HSD1 activity and glucocorticoid receptor (GR) activation in transfected HEK-293 cells. Leave extracts of Eriobotrya japonica preferentially inhibited 11β-HSD1 over 11β-HSD2. Extracts of roasted but not native coffee beans preferentially inhibited 11β-HSD1 over 11β-HSD2, emphasizing the importance of sample preparation. Thus, natural compounds inhibiting 11β-HSD1 may contribute to the antidiabetic effect of the investigated plant extracts.     

Antidiabetic potential of Phyllanthus reticulatus in alloxan-induced diabetic mice

The plant Phyllanthus reticulatus is claimed to have antidiabetic activity in tribal area. To validate the tribal claim, the petroleum ether and ethanolic extracts of leaves of the P. reticulatus were orally tested at 500 and 1000 mg/kg for hypoglycemic effect in alloxan induces diabetic mice. It shows antidiabetic activity at the dose of 1000 mg/kg. The phytochemical screening of the residues revealed the presence of terpenoids glycosides, protein, carbohydrates and absence of alkaloids and steroids.     

4-Hydroxyisoleucine improves insulin resistance by promoting mitochondrial biogenesis and act through AMPK and Akt dependent pathway

4-Hydroxyisoleucine (4-HIL) is an unusual amino acid isolated from fenugreek seeds (Trigonella foenum graecum L). Various studies have shown that it acts as an antidiabetic agent yet its mechanism of action is not clear. We therefore investigated the effect 4-HIL on the high fructose diet fed streptozotocin induced diabetic rats and L6 myotubes. 4-HIL (50 mg/kg) has improved blood lipid profile, glucose tolerance and insulin sensitivity in a diabetic rat model. It has increased the glucose uptake in L6 myotubes in AMPK-dependent manner and upregulated the expression of genes (PGC-1α, PGC-1β, CPT 1 and CPT 2), which have role in mitochondrial biogenesis and energy metabolism in the liver, skeletal muscles as well as in L6 myotubes. Interestingly, it also increased the AMPK and Akt expression along with their phosphorylated forms in the liver and muscle tissues of treated animals. Altogether we concluded that 4-HIL acts to improve insulin resistance by promoting mitochondrial biogenesis in high fructose diet fed STZ induced diabetic rats.     

Evaluation of antidiabetic effect of Momordica cymbalaria fruit in alloxan-diabetic rats

The oral treatment with the aqueous extract of Momordica cymbalaria fruit (MC) (0.5 g/kg) for 6 weeks showed a significant antihyperglycemic as well as antihyperlipidemic effects in the alloxan-induced diabetic rats.     

Bioactive plants from Argentina and Bolivia

Antibacterial and molluscicidal activities of methanol and chloroform extracts of 16 plant species belonging to the families Compositae and Melastomataceae were evaluated. The chloroform extract of Vernonanthura tweediana and the methanol extract of Senecio santelisis resulted to be very toxic to brine shrimp nauplii (LC(50)=1 microg/ml). Chloroform extracts of S. santelisis and Senecio leucostachys as well as the methanol extract of Wedelia subvaginata displayed molluscicidal effects on Biomphalaria peregrina showing LC(100)<100 microg/ml. Moderate antibacterial action was produced by the chloroform extracts of Flaveria bidentis, Grindelia scorzonerifolia and Vernonia incana against two strains of Staphylococcus aureus.     

Hypoglycemic and hypocholesterolemic activities of the aqueous leaf and seed extract of Phyllanthus amarus in mice

The effect of the aqueous leaf and seed extracts of Phyllanthus amarus at oral dose of 150, 300 and 600 mg/kg was investigated for their antidiabetic and anti-lipidemic potentials. The extract produced a dose-dependent decrease in the fasting plasma glucose and cholesterol, and reduction in weights in treated mice. The results suggest that the extract could be enhancing peripheral utilization of glucose but the mechanisms on how this works remain unclear.     

Antidiabetic potential of Butea monosperma in rats

The antihyperglycemic activity of the ethanolic extract of Butea monosperma (BMEE) was studied in glucose-loaded and alloxan-induced diabetic rats. Single dose treatment of BMEE (200 mg/kg, p.o.) significantly improved glucose tolerance and caused reduction in blood glucose level in alloxan-induced diabetic rats. Repeated oral treatment with BMEE (200 mg/kg/day) for 2 weeks significantly reduced blood glucose, serum cholesterol and improved HDL-cholesterol and albumin as compared to diabetic control group.     

Hibiscus sabdariffa L. in the treatment of hypertension and hyperlipidemia: A comprehensive review of animal and human studies

The effectiveness of Hibiscus sabdariffa L. (HS) in the treatment of risk factors associated with cardiovascular disease is assessed in this review by taking a comprehensive approach to interpreting the randomized clinical trial (RCT) results in the context of the available ethnomedical, phytochemical, pharmacological, and safety and toxicity information. HS decoctions and infusions of calyxes, and on occasion leaves, are used in at least 10 countries worldwide in the treatment of hypertension and hyperlipidemia with no reported adverse events or side effects. HS extracts have a low degree of toxicity with a LD₅₀ ranging from 2,000 to over 5,000 mg/kg/day. There is no evidence of hepatic or renal toxicity as the result of HS extract consumption, except for possible adverse hepatic effects at high doses. There is evidence that HS acts as a diuretic, however in most cases the extract did not significantly influence electrolyte levels. Animal studies have consistently shown that consumption of HS extract reduces blood pressure in a dose dependent manner. In RCTs, the daily consumption of a tea or extract produced from HS calyxes significantly lowered systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults with pre to moderate essential hypertension and type 2 diabetes. In addition, HS tea was as effective at lowering blood pressure as the commonly used blood pressure medication Captropril, but less effective than Lisinopril. Total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides were lowered in the majority of normolipidemic, hyperlipidemic, and diabetic animal models, whereas high-density lipoprotein cholesterol (HDL-C) was generally not affected by the consumption of HS extract. Over half of the RCTs showed that daily consumption of HS tea or extracts had favorable influence on lipid profiles including reduced total cholesterol, LDL-C, triglycerides, as well as increased HDL-C. Anthocyanins found in abundance in HS calyxes are generally considered the phytochemicals responsible for the antihypertensive and hypocholesterolemic effects, however evidence has also been provided for the role of polyphenols and hibiscus acid. A number of potential mechanisms have been proposed to explain the hypotensive and anticholesterol effects, but the most common explanation is the antioxidant effects of the anthocyanins inhibition of LDL-C oxidation, which impedes atherosclerosis, an important cardiovascular risk factor. This comprehensive body of evidence suggests that extracts of HS are promising as a treatment of hypertension and hyperlipidemia, however more high quality animal and human studies informed by actual therapeutic practices are needed to provide recommendations for use that have the potential for widespread public health benefit.     

Antidiabetic properties of aqueous barks extract of Parinari excelsa in alloxan-induced diabetic rats

The aqueous extract of the Parinari excelsa barks at doses of 100 and 300 mg/kg/day for 7 days has a significant antihyperglycemic effect on alloxan-induced diabetic rats. At the same dose the acute oral administration of aqueous extract of the P. excelsa barks (100 and 300 mg/kg) induced a significant decrease of blood glucose on glucose-loaded normoglycaemic rats. Our results seem to confirm the rational bases for its use in traditional medicine.     

Ilex paraguariensis extracts inhibit AGE formation more efficiently than green tea

Glycation, the nonenzymatic adduct formation between sugar dicarbonyls and proteins, is one key molecular basis of diabetic complications due to hyperglycemia. Given the link between glycation and oxidation, we hypothesized that herbal extracts with a high concentration of antioxidant phenolics might possess significant in vitro antiglycation activities as well. The aim of the present study was to address the hypothesis that polyphenol-rich Ilex paraguariensis (IP) extracts are capable of inhibiting advanced glycation end-products (AGEs) formation and to compare the potency of these extracts with green tea and with the standard antiglycation agent aminoguanidine. When we studied the effects of IP extract on AGE fluorescence generated on bovine serum albumin (BSA) by glycation with methylglyoxal, a dose-dependent effect that reaches 40% at 20 mul/ml of extract was demonstrated. Green tea did not display any significant effect. IP polyphenols are about 2- to 2.5-fold higher in our preparations compared with green tea. The effect of IP, therefore, may be due not only to the higher concentrations but to the different composition in phenolics of the two botanical preparations as well. To better discriminate between an antioxidant or a carbonyl quenching mechanism of action, we explored tryptophan fluorescence and cross-linking by sodium dodecyl sulfate polyacrylamide gel (SDS-PAGE) electrophoresis. The conformational changes induced by glycation and substitution of positive charges in arginine and/or lysine produce a decrease in tryptophan fluorescence. We show that incubation of BSA with methylglyoxal produces dramatic changes in tryptophan fluorescence that are prevented by aminoguanidine. This also prevents the downstream effect of AGE formation. Neither green tea nor IP extracts displayed any significant effect which rules out any significant participation as inhibitors in the first phase of the glycation cascade. The results from the SDS-PAGE serve to confirm the above-mentioned data. The effect is therefore due mainly to an inhibition of the second phase of the glycation reactions, namely the free-radical mediated conversion of the Amadori products to AGE. Taken together our results demonstrate a significant, dose-dependent effect of water extracts of I. paraguensis on AGE adducts formation on a protein model in vitro, whereas green tea displays no significant effect. The inhibition of AGE formation was comparable to that obtained by using millimolar concentrations of the standard antiglycation agent aminoguanidine.