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Antinociceptive, anti-inflammatory and antidiabetic properties of Hypoxis hemerocallidea Fisch. & C.A. Mey. (Hypoxidaceae) corm ['African Potato'] aqueous extract in mice and rats.

In order to scientifically appraise some of the anecdotal, folkloric, ethnomedical uses of Hypoxis hemerocallidea Fisch. & C.A. Mey. (Hypoxidaceae) corm ['African Potato'], the present study was undertaken to examine the antinociceptive, anti-inflammatory and antidiabetic properties of the corm's aqueous extract (APE) in mice and rats. The antinociceptive effect of APE was evaluated by 'hot-plate' and 'acetic acid' analgesic test methods in mice; while the anti-inflammatory and antidiabetic effects of the plant's extract were investigated in rats, using fresh egg albumin-induced pedal (paw) oedema, and streptozotocin (STZ)-induced diabetes mellitus models. Morphine (MPN, 10 mg/kg), diclofenac (DIC, 100 mg/kg) and chlorpropamide (250 mg/kg) were used as reference drugs for comparison. H. hemerocallidea corm aqueous extract (APE, 50-800 mg/kg i.p.) produced dose-dependent, significant (P < 0.05-0.001) antinociceptive effects against thermally- and chemically-induced nociceptive pain stimuli in mice. The plant extract (APE, 50-800 mg/kg p.o.) also significantly (P < 0.05-0.001) inhibited fresh egg albumin-induced acute inflammation, and caused dose-related, significant (P < 0.05-0.001) hypoglycaemia in normal (normoglycaemic) and diabetic rats. The results obtained in this study suggest that the antinociceptive effects of the plant's extract are peripherally- and centrally-mediated. The findings of this experimental animal study indicate that H. hemerocallidea corm aqueous extract (APE) possesses antinociceptive, anti-inflammatory and antidiabetic properties; and thus lend pharmacological support to folkloric, anecdotal uses of 'African Potato' in the treatment and/or management of painful, arthritic inflammatory conditions, as well as in the management and/or control of type-2 diabetes mellitus in some parts of southern Africa.

Analgesics↗

Antidiabetic effect of garlic (Allium sativum L.) in normal and streptozotocin-induced diabetic rats.

OBJECTIVE: The antidiabetic effect of garlic ethanolic extract (Allium sativum L.) was investigated in normal and streptozotocin-induced diabetic rats. RESEARCH METHODS AND PROCEDURE: In the present study, oral administration of garlic extract (0.1, 0.25 and 0.5 g/kg body wt.) for 14 days on the level of serum glucose, total cholesterol, triglycerides, urea, uric acid, creatinine, aspartate amino transferase (AST) and alanine amino transferase (ALT) in normal and streptozotocin-induced diabetic rats were evaluated. RESULTS: Oral administrations of the garlic extract significantly decreased serum glucose, total cholesterol, triglycerides, urea, uric acid, creatinine, AST and ALT levels, while increased serum insulin in diabetic rats but not in normal rats (p<0.05). A comparison was made between the action of garlic extract and glibenclamide (600 microg/kg), the known antidiabetic drug. The antidiabetic effect of the extract was more effective than that observed with glibenclamide. CONCLUSION: It is concluded that the plant must be considered as excellent candidate for future studies on diabetes mellitus.

Alanine Transaminase↗

Effects of physician specialty on use of antidiabetes drugs, process and outcomes of diabetes care in a medical center.

BACKGROUND/PURPOSE: Physician characteristics might determine the quality of diabetes care. This study evaluated the effects of physician specialty on the use of antidiabetes drugs, process and outcomes of diabetes care. METHODS: In 2002, 12,023 diabetes patients visited outpatient clinics more than four times at National Taiwan University Hospital. One-tenth of the patients were randomly sampled out. A retrospective chart review was conducted for those who were regularly cared for by endocrinologists (EN), other specialists in internal medicine (IM) and family medicine (FM) physicians. The use of antidiabetes drugs was assessed. Effects of physician specialty on the process or outcome indicators were analyzed by logistic or linear regression, accordingly. RESULTS: A total of 875 diabetes patients (477 men, 398 women) with a mean age of 62.3 +/- 12.7 years were recruited. EN patients had the highest rate of being prescribed insulin, metformin or nonsulfonylurea insulin secretagogues, and the lowest rate of being given sulfonylureas. EN patients showed a significantly better adherence to glucose checkup, glycosylated hemoglobin A1C measures and urinalysis than IM patients. EN patients also showed better adherence to glucose checkup and urinalysis than FM patients. EN patients had the lowest mean fasting plasma glucose (FPG) and lowest mean postprandial plasma glucose (PPG). The difference in PPG between EN and IM patients and the difference in FPG between EN and FM patients were persistently significant following adjustment by patient and physician characteristics. CONCLUSION: The use of antidiabetes drugs differed among patients cared for by EN, internists or generalists. Physician specialty had significant effects on the process and outcomes of diabetes care.

Adult↗

Inhibiting effects of antioxidants on drug-induced phototoxicity in cell cultures. Investigations with sulphonamide-derived oral antidiabetics and diuretics.

The sulphonamide-derived oral antidiabetics chlorpropamide, glibenclamide, glipizide, gliquidone, glymidine, tolazamide and tolbutamide, and the diuretics bemetizide, bendroflumethiazide, benzylhydrochlorothiazide, bumetanide, butizide, chlortalidone, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, piretanide, polythiazide, trichlormethiazide and xipamide were investigated for phototoxicity in a cell culture model. Cell death dependent on ultraviolet A (UVA) radiation fluence and test substance concentration was observed in the presence of the oral antidiabetics glibenclamide and gliquidone, as well as the diuretics bemetizide, bendroflumethiazide, benzylhydrochlorothiazide, bumetanide, butizide, hydrochlorothiazide, hydroflumethiazide, piretanide, polythiazide and trichlormethiazide. Bendroflumethiazide was phototoxic at concentrations of 0.05 mM and above; bemetizide, benzylhydrochlorothiazide, bumetanide and hydroflumethiazide were phototoxic at concentrations of 0.25 mM or more; the oral antidiabetics glibenclamide and gliquidone, as well as the diuretics butizide, hydrochlorothiazide, piretanide, polythiazide and trichlormethiazide were phototoxic at concentrations of 0.5 mM. To evaluate the effects of antioxidants, ascorbic acid, alpha-tocopherol, beta-carotene or ubiquinone was added to the tissue culture flasks before irradiation. The phototoxic inhibition of the colony-forming ability was largely reduced by the addition of ascorbic acid and alpha-tocopherole, indicating the involvement of reactive oxygen species in the phototoxic process.

Antioxidants↗

Combination therapy with pioglitazone plus metformin or sulfonylurea in patients with Type 2 diabetes: influence of prior antidiabetic drug regimen.

PURPOSE: To evaluate two trials of combination therapy, pioglitazone together with metformin or sulfonylurea, for Type 2 diabetes mellitus and to examine how pretrial antidiabetic therapies may have influenced the results. SUBJECTS AND METHODS: The results of two published trials that examine combination therapy, pioglitazone plus metformin or pioglitazone plus sulfonylurea were analyzed. A post hoc analysis was performed in which patients from both of these trials were subdivided on the basis of their oral antidiabetic therapy before enrollment into the trials. Those subsets receiving pretrial therapy with a sulfonylurea plus metformin - and discontinuing one of the agents before randomization - were compared to those receiving only one of the agents before enrollment. RESULTS: Patients in the combination pioglitazone (30 mg/day) plus metformin therapy arm of one trial, who entered with stable metformin monotherapy, experienced a significant decrease in glycosylated hemoglobin (HbA(1C)) levels during the 16-week course of the trial (-1.0+/-0.1 [mean+/-S.E.] percentage points; P<.05). In contrast, those in the same arm of the trial whose pretrial therapy included metformin plus a sulfonylurea - and who discontinued the sulfonylurea before enrollment - experienced no significant change in HbA(1C) levels (0.2+/-0.2 percentage points; P>.05). The difference between groups was significant (P<.001). Patients in the combination pioglitazone (15 or 30 mg/day) plus sulfonylurea therapy arm of the other trial, who entered the trial on stable sulfonylurea monotherapy, experienced significant decreases in HbA(1C) levels (-1.0+/-0.1 and -1.4+/-0.1 percentage points, respectively, for the 15- and 30-mg pioglitazone arms; P<.05). Those in the same arm whose pretrial therapy included sulfonylurea plus metformin - and who discontinued the metformin before enrollment - experienced no significant change in HbA(1C) levels. Differences between the groups separated on the basis of pretrial antidiabetic regimen were significant (P<.001). CONCLUSIONS: The efficacy of pioglitazone as an add-on in combination therapy (with metformin or a sulfonylurea) is likely to be greater than in previous reports, because those trial results were influenced by treatment regimens used by a portion of the patients before enrollment. Trials of oral hypoglycemic agents must be carefully constructed to consider the effects of agents given prior to the trial.

Administration, Oral↗

Antidiabetic effect of Cogent db, a herbal drug in alloxan-induced diabetes mellitus.

Cogent db, a compound herbal drug, was investigated for its possible antidiabetic effect in alloxan-induced diabetic rats. Oral administration of 0.15, 0.30 and 0.45 g/kg body wt. of the aqueous solution of Cogent db for 40 days exhibited a significant reduction in blood glucose, glycosylated haemoglobin and increased plasma insulin, total haemoglobin along with antihyperlipidemic effects in diabetic rats. The effective dose was found to be 0.45 g/kg body wt. It also prevents body weight loss in diabetic rats. An oral glucose tolerance test (OGTT) was also performed in experimental diabetic rats in which there was a significant improvement in glucose tolerance in rats treated with Cogent db. A comparison was made between the action of Cogent db and a known antidiabetic drug--glibenclamide (600 microg/kg body wt.). The antidiabetic effect of Cogent db was more effective than that observed with glibenclamide.

Alloxan↗

Bis(allixinato)oxovanadium(IV) complex is a potent antidiabetic agent: studies on structure-activity relationship for a series of hydroxypyrone-vanadium complexes.

There is an urgent medical need for orally effective drugs to replace insulin injections for the treatment of diabetes mellitus. Vanadium complexes with insulin-mimetic activities have recently been proposed as candidates as new antidiabetic drugs. Following in vitro and in vivo studies on a group of bis(3-hydroxy-4-pyronato)oxovanadium(IV) (1) complexes with VO(O4) coordination mode, bis(allixinato)oxovanadium(IV) (3) which contains allixin, a garlic component, was found to be the most potent antidiabetic agent among them. Complex 3 with a high in vitro insulin-mimetic activity in terms of both free fatty acid (FFA)-release inhibitory and glucose-uptake enhancing activities in isolated rat adipocytes exhibited a high hypoglycemic effect in type 1 diabetic model mice by both intraperitoneal injections and oral administrations. Complex 3 is thus proposed to be one of the most effective candidates for antidiabetic therapy.

Adipocytes↗

Antidiabetic sulphonylureas activate mitochondrial permeability transition in rat skeletal muscle.

Antidiabetic sulphonylureas can bind to various intracellular organelles including mitochondria. The aim of this study was to monitor the influence of antidiabetic sulphonylureas on membrane permeability in mitochondria isolated from rat skeletal muscle. The effects of glibenclamide (and other sulphonylurea derivatives) on mitochondrial function were studied by measuring mitochondrial swelling, mitochondrial membrane potential, respiration rate and Ca2+ transport into mitochondria. We observed that glibenclamide induced mitochondrial swelling (EC50 = 8.2 +/- 2.5 microM), decreased the mitochondrial membrane potential and evoked Ca2+ efflux from the mitochondrial matrix. These effects were blocked by 2 microM cyclosporin A, an inhibitor of the mitochondrial permeability transition. Moreover, 30 microM glibenclamide accelerated the respiratory rate in the presence of glutamate/malate, substrates of complex I of the mitochondrial respiratory chain. In conclusion, we postulate that the antidiabetic sulphonylureas activate the mitochondrial permeability transition in skeletal muscle by increasing its sensitivity to Ca2+.

Animals↗

Synergistic antidiabetic activities of zinc, cyclo (his-pro), and arachidonic acid.

Previous studies have already shown that prostate extract (PE) has antidiabetic activity when given to animals and humans. In this study, we explore whether this antidiabetic activity is related to the high concentrations of zinc, cyclo (his-pro) (CHP), and the prostaglandin precursor, arachidonic acid (AA), in prostate tissue. When streptozotocin-induced diabetic rats were given drinking water containing 10 mg/L zinc and 100 mg/L PE for 3 weeks, fasting blood glucose levels and glucose clearance rates, but not plasma insulin levels, were significantly lower than at pretreatment. In subsequent experiments, blood glucose levels in rats given PE for 3 weeks were significantly lower than in rats given distilled water or 10 mg/L zinc alone. However, in rats given 100 mg/L CHP with zinc, blood glucose levels were also lower than in rats given PE alone. Time-course studies in diabetic rats given drinking water containing 20 mg/L Zn, 20 mg/L L-histidine, and 10 mg/L CHP showed that blood glucose levels dropped 209 +/- 53 mg/dL in 1 day and stayed low for 2 weeks. When CHP was replaced with 100 mg AA/L, blood glucose levels dropped 230 +/- 64 mg/dL in 5 days, but returned to the original values 11 days later. Growth rate improved and water consumption decreased significantly in CHP- and AA-treated diabetic rats. High intake of L-histidine and testosterone increased blood glucose concentrations in diabetic rats. To determine optimal dosages of CHP and AA, we gave rats drinking water containing 10 mg/L Zn and 0.5 mg/L L-histidine with various concentrations of CHP or AA. The most effective doses for reducing blood glucose levels were 0.32 mg CHP/kg/day and 11 mg AA/kg/day. These data suggest that the active antidiabetic ingredients in the PE are CHP, zinc, and AA or its precursors.

Animals↗

Influence of an antidiabetic treatment with sulfonylurea drugs on long-term survival after acute myocardial infarction in patients with type 2 diabetes. The LAngendreer Myocardial infarction and Blood glucose in Diabetic patients Assessment (LAMBDA).

INTRODUCTION: Patients with type 2 diabetes show a significantly higher mortality after acute myocardial infarction than non-diabetic patients. The influence of sulfonylureas on the survival after acute myocardial infarction is still under debate. PATIENTS AND METHODS: Survival of 562 patients, consecutively admitted to an intensive care unit with the diagnosis acute myocardial infarction, was prospectively assessed for > 3 years. At the time of hospital admission, patients were grouped as (a) non-diabetic patients; (b) patients with newly diagnosed type 2 diabetes; (c) patients with known type 2 diabetes not treated with sulfonylureas and (d) patients with known type 2 diabetes treated with sulfonylureas. Survival-analysis was performed according to Kaplan-Meier. RESULTS: 324 patients were non-diabetics, in 86 cases type 2 diabetes was newly diagnosed at the time of hospital admission, 77 patients with known diabetes had taken sulfonylureas (glibenclamide in all cases) prior to the acute myocardial infarction, 75 patients were on any other antidiabetic treatment. Long-term-survival was significantly shorter in patients with type 2 diabetes compared to the non-diabetic patients (p < 0.0001). However, no significant differences were observed between the patients with type 2 diabetes treated with sulfonylurea-drugs and those receiving any other antidiabetic treatment (p = 0.53) CONCLUSIONS: An antidiabetic treatment with sulfonylurea-drugs prior to acute myocardial infarction does not have negative effects on the long-term survival. Larger prospective studies will be necessary to finally clarify this question.

Acute Disease↗

Soy isoflavones exert antidiabetic and hypolipidemic effects through the PPAR pathways in obese Zucker rats and murine RAW 264.7 cells.

The hypocholesterolemic and anti-atherosclerotic mechanism by which soy may exert a beneficial effect remains unclear. Peroxisome-proliferator activated receptors (PPAR) are promiscuous nuclear receptors that regulate the transcription of genes involved in lipid and glucose homeostasis and lipid metabolism within the cell. We hypothesize that the isoflavones improve lipid and glucose metabolism by acting as an antidiabetic PPAR agonist. Male and female obese Zucker rats (OZR) were used as a model of Type 2 diabetes, and OZR fed a high isoflavone soy protein diet displayed improvements in lipid metabolism consistent with results in humans treated with antidiabetic PPAR agonists such as the fibrates or glitazones. Liver triglyceride and cholesterol concentrations were lower in all OZR fed high-isoflavone soy protein diets than in rats fed low-isoflavone and casein diets (P < 0.05). Concurrently, PPAR-directed gene expression was evaluated in a cell culture model. An isoflavone-containing soy extract doubled PPAR-directed gene expression (P < 0.05) in RAW 264.7 cells containing either a PPARalpha or PPARgamma expression plasmid. A similar induction was observed when the soy isoflavones genistein or daidzein were used to treat cells. Both isoflavones doubled PPARalpha-directed gene expression (P < 0.05), whereas they increased PPARgamma-directed gene expression 200-400% (P < 0.05). This study suggests that soy isoflavones improve lipid metabolism, produce an antidiabetic effect, and activate PPAR receptors.

Animals↗

Possible antidiabetic and antihyperlipidaemic effect of fermented Parkia biglobosa (JACQ) extract in alloxan-induced diabetic rats.

1. The hypoglycaemic effect of fermented seeds of Parkia biglobosa (PB; African locust bean), a natural nutritional condiment that features frequently in some African diets as a spice, was investigated in the present study in alloxan-induced diabetic rats. Its effect was compared with that of glibenclamide (Daonil; Sanofi-Aventis, Paris, France), a reference antidiabetic drug. The effects of PB on lipid profiles were also examined. 2. In order to assess the hypoglycaemic and hypolipidaemic effects of aqueous and methanolic extracts of PB on experimental animals, fasting plasma glucose (FPG), total cholesterol, triglyceride, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) were determined. In addition, the weight of each animal was determined to assess any possible weight gain or loss in the experimental animals (diabetic rats treated with Daonil (group C), the aqueous extract of PB (group D) or the methanolic extract of PB (group E)) compared with control groups (non-diabetic (group A) and non-treated diabetic (group B)). 3. A single dose of 120 mg/kg, i.v., alloxan administered to rats resulted in significant increases in the FPG (P < 0.001) of test animals compared with controls. However, dietary supplementation with PB (6 g/kg extract for 4 weeks administered orally using an intragastric tube) ameliorated the alloxan-induced diabetes in a manner comparable with that of the reference antidiabetic drug glibenclamide. Aqueous and methanolic extracts of PB (6% w/w) elicited 69.2% and 64.4% reductions, respectively, in FPG compared with 70.4% in 0.01 mg/150 g glibenclamide-treated rats. 4. Although animals treated with the aqueous extract of PB gained weight in manner similar to normal controls, animals given the methanolic extract and glibenclamide lost weight in manner similar to non-treated diabetic rats. In addition, high levels of HDL and low LDL were observed in animals treated with the aqueous extract of PB, a pattern similar to that seen in normal controls. Low levels of HDL and high levels of LDL were observed in animals treated with the methanolic extract of PB, a pattern similar to that seen in non-treated diabetic controls. 5. The results of the present study demonstrate that both aqueous and methanolic extracts of fermented seeds of PB exert a hypoglycaemic effect; hence, PB has an antidiabetic property. However, only the aqueous extract of PB ameliorated the loss of bodyweight usually associated with diabetes. Although the aqueous extract has a favourable lipid profile, which is probably an indication of its possible anti-arteriogenic property (hypertension and ischaemic heart diseases being common complications in diabetes mellitus), the methanolic extract shows possible contraindication to ischaemic heart diseases.

Animals↗

A comparison of intensive mixture therapy with basal insulin therapy in insulin-naïve patients with type 2 diabetes receiving oral antidiabetes agents.

AIM: In patients with type 2 diabetes, insulin therapy is commonly initiated with either a single dose of basal insulin or twice-daily premixed (basal plus prandial) insulin despite no widely accepted recommendation. We compared the glycaemic control, as measured by a change in HbA1c, of intensive mixture therapy (IMT), a basal plus prandial regimen using insulin lispro mixture 50/50 (50% lispro and 50% NPL) before breakfast and lunch and insulin lispro mixture 25/75 (25% lispro and 75% NPL) before dinner, vs. once-daily insulin glargine therapy, while continuing patients on oral antidiabetes medications. METHODS: Following inadequate glycaemic control (HbA1c 1.2-2.0 times the upper limit of normal) and at least 2 months of two or more oral antidiabetes agent therapy, 60 insulin-naïve patients with type 2 diabetes were randomized to one of the insulin regimens for 4 months with crossover to the alternative regimen for an additional 4 months. Glycaemic goals were preprandial blood glucose <120 mg/dl (6.7 mmol/l) and 2-h postprandial blood glucose <180 mg/dl (10.0 mmol/l). The insulin dose was optimized by investigators without forced titration. RESULTS: Mean prestudy (baseline) HbA1c for all patients was 9.21 +/- 1.33% (+/-s.d.). IMT compared to glargine resulted in both a lower endpoint in HbA1c (7.08 +/- 0.11% vs. 7.34 +/- 0.11%; p = 0.003) and a greater change in HbA1c from pretherapy (-1.01 +/- 0.10% vs. -0.75 +/- 0.10%; p = 0.0068). Forty-four per cent of patients receiving IMT and 31% of patients receiving insulin glargine achieved HbA1c < or = 7%. Two-hour postprandial glucose values (for all three meals) and predinner glucose values were significantly less with IMT than with insulin glargine (p = 0.0034, 0.0001, 0.0066 and 0.0205). Overall hypoglycaemia throughout the complete treatment period was infrequent (IMT vs. Glargine: 3.98 +/- 4.74 vs. 2.57 +/- 3.22 episodes/patient/30 days, p = 0.0013), and no severe hypoglycaemia was observed during the study with either therapy. There was no difference in nocturnal hypoglycaemia between the two therapies. The mean insulin dose at the end of therapy was greater for IMT than for once-daily insulin glargine (0.353 +/- 0.256 vs. 0.276 +/- 0.207 IU/kg, p = 0.0107). CONCLUSIONS: In combination with oral antidiabetes agents, multiple daily injections of a basal plus prandial insulin IMT regimen (using premixed insulin lispro formulations) resulted in greater improvements and a lower endpoint in HbA1c compared with a basal-only insulin regimen. IMT also resulted in improved postprandial blood glucose control at each meal and enabled administration of a greater daily dose of insulin, which most likely contributed to these lower HbA1c measures. This greater reduction in HbA1c with IMT is accompanied by a small increased occurrence of mild hypoglycaemia but without any severe hypoglycaemia. Greater consideration should be given to initiating insulin as a basal plus prandial regimen rather than a basal-only regimen.

Adult↗

Phototoxicity due to sulphonamide derived oral antidiabetics and diuretics: investigations in a cell culture model.

A number of sulphonamide-derived oral antidiabetics (chlorpropamide, glibenclamide, glipizide, gliquidone, glymidine, tolazamide and tolbutamide) and diuretics (bemetizide, bendroflumethiazide, benzylhydrochlorothiazide, bumetanide, butizide, chloratalidone, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, piretanide, polythiazide, trichlormethiazide and xipamide) were investigated for phototoxicity in a cell culture model. Cell death dependent on ultraviolet A fluence and test substance concentration was observed in the presence of the oral antidiabetics glibenclamide and gliquidone, as well as the diuretics bemetizide, bendroflumethiazide, benzyl-hydrochlorothiazide, bumetanide, butizide, hydrochlorothiazide, hydroflumethiazide, piretanide, polythiazide and trichlormethiazide. Bendroflumethiazide was phototoxic at 5x10(-5) M and higher concentrations, bemetizide, benzylhydrochlorothiazide, bumetanide and hydroflumethiazide were phototoxic at 2.5x10(-4) M and higher concentrations, and the oral antidiabetics glibenclamide and gliquidone as well as the diuretics butizide, hydrochlorothiazide, piretanide, polythiazide and trichlormethiazide were phototoxic at 5(-4) M and higher concentrations. Electron microscopic investigations showed swelling of mitochondria and endoplasmic reticulum as well as aggregation of euchromatin when the cells were irradiated in the presence of photosensitizers.

Administration, Oral↗

Chronic antidiabetic and cardiovascular actions of leptin: role of CNS and increased adrenergic activity.

This study examined the importance of direct central nervous system (CNS) actions and increased adrenergic activity in mediating the chronic antidiabetic and cardiovascular actions of leptin. Insulin-deficient rats (streptozotocin, 50 mg/kg) were used to examine the effects of leptin on glucose homeostasis independent of changes in insulin. Male Sprague-Dawley rats were instrumented with arterial and venous catheters and intracerebroventricular cannula for 24-h/day blood pressure (BP) and heart rate (HR) monitoring and intravenous and intracerebroventricular infusions. Insulin-deficient diabetes was associated with marked hyperglycemia, hyperphagia, decreased BP, and pronounced fall in HR. Leptin treatment, intravenous or intracerebroventricular, completely restored to control values plasma glucose levels (384+/-58 to 102+/-28 and 307+/-38 to 65+/-7 mg/dl, respectively), food intake, BP, and HR (304+/-8 to 364+/-7 and 317+/-13 to 423+/-9 bpm, respectively). Combined blockade of alpha1-, beta1-, and beta2-adrenergic receptors attenuated the rise in HR by 30 to 50% but had no effect on the antidiabetic and dietary actions of leptin. Blockade of beta3-adrenergic receptors did not attenuate the chronic cardiovascular or metabolic effects of leptin. These data demonstrate that leptin, via its direct actions in the CNS, has powerful antidiabetic actions in insulin-deficient rats independent of increased peripheral alpha1, beta1, beta2, and beta3-adrenergic activity. Leptin also exerts important long-term cardiovascular actions that are partially mediated via alpha1- and beta1/beta2-adrenergic activation. These findings provide new insights into novel pathways for long-term control of glucose homeostasis and cardiovascular regulation.

Animals↗

Metabolism of kalopanaxsaponin B and H by human intestinal bacteria and antidiabetic activity of their metabolites.

To investigate the relationship between the intestinal bacterial metabolism of kalopanaxsaponin B and H from Kalopanax pictus (Araliaceae), and their antidiabetic effect, kalopanaxsaponin B and H were metabolized by human intestinal microflora and the antidiabetic activity of their metabolites was measured. Human intestinal microflora metabolized kalopanaxsaponin B to kalopanaxsaponin A, hederagenin 3-O-alpha-L-arabinopyranoside and hederagenin. The main metabolites of kalopanaxsaponin B were kalopanaxsaponin A and hederagenin. Kalopanaxsaponin H was metabolized to kalopanaxsaponin A and I, hederagenin 3-O-alpha-L-arabinopyranoside and hederagenin. The main metabolites of kalopanaxsaponin H were kalopanaxsaponin I and hederagenin. Among kalopanaxsaponin B, H and their metabolites, kalopanaxsaponin A showed the most potent antidiabetic activity, followed by hederagenin. However, the main components, kalopanaxsaponin B and H, in K. pictus were inactive.

Animals↗

Na(+)-glucose cotransporter inhibitors as antidiabetics. I. Synthesis and pharmacological properties of 4'-dehydroxyphlorizin derivatives based on a new concept.

Based on our new concept that inhibitors of the Na(+)-glucose cotransporter (SGLT) would be useful as antidiabetics, 4'-dehydroxyphlorizin derivatives 1a--f were designed, synthesized, and examined for various pharmacological properties related to antidiabetic activity. In normal rats, 1a, e and phlorizin showed a strong SGLT-inhibitory effect and significantly increased urinary glucose on intraperitoneal administration at 10 mg/kg, though only 1a resulted in excretion of large quantities of urinary glucose on oral administration at 100 mg/kg. Compounds 1a, e, and phlorizin markedly inhibited glucose uptake in the small intestine during enteric perfusion in normal rats. Compound 1a had a significant reducing effect on blood glucose in the glucose tolerance test in mice when administered orally and also lowered blood glucose in streptozotocin-induced diabetic rats. The aglycons 2a, e of 1a, e, and 1a showed weak inhibitory effects on the facilitated glucose transporter-1 (GLUT-1) in human erythrocytes, while phloretin had a strong inhibitory effect on GLUT-1. Compound 1a caused no apparent renal damage in rats when administered orally at 1 g/kg for 4 successive weeks. Thus, 1a was considered to be a promising candidate as a lead compound for antidiabetics of a new type, and was selected for further pharmacological evaluation.

Animals↗