Comparative and combined effect of chlorogenic acid and tetrahydrocurcumin on antioxidant disparities in chemical induced experimental diabetes

The present study evaluates the combined effect of tetrahydrocurcumin and chlorogenic acid on oxidative stress in streptozotocin–nicotinamide-induced diabetic rats. Rats were rendered diabetic by a single intraperitoneal injection (i.p) of streptozotocin (45 mg/kg BW), 15 min after an i.p injection of nicotinamide (110 mg/kg BW). The levels of fasting plasma glucose and insulin were estimated. As an index of oxidative stress, the levels of enzymic antioxidants and lipid peroxidation products were analyzed in liver and kidney. Diabetic rats showed an increase in the levels of fasting plasma glucose, lipid peroxidative products such as thiobarbituric acid reactive substances and lipid hydroperoxides and a decrease in plasma insulin, and enzymic antioxidants viz., superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase. Combined administration of tetrahydrocurcumin (80 mg/kg BW) and chlorogenic acid (5 mg/kg BW) to diabetic rats for 45 days, reversed the biochemical changes to near normal. The above findings were supported by histological observations of the liver and kidney. Together the present study clearly reflects that combined dosage of tetrahydrocurcumin and chlorogenic acid augments enzymic antioxidants with a concomitant decrease in lipid peroxidation and protects against streptozotocin–nicotinamide-induced type 2 diabetes in experimental rats.     

Antioxidant effect of tetrahydrocurcumin in streptozotocin-nicotinamide induced diabetic rats

Oxidative stress has been suggested to be a contributory factor in development and complication of diabetes. In the present study, we have investigated the effect of tetrahydrocurcumin (THC), one of the active metabolites of curcumin on antioxidants status in streptozotocin-nicotinamide induced diabetic rats. Oral administration of THC at 80 mg/kg body weight of diabetic rats for 45 days resulted in significant reduction in blood glucose and significant increase in plasma insulin levels. In addition, THC caused significant increase in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, reduced glutathione, vitamin C and vitamin E in liver and kidney of diabetic rats with significant decrease in thiobarbituric acid reactive substances (TBARS) and hydroperoxides formation in liver and kidney, suggesting its role in protection against lipid peroxidation induced membrane damage. These biochemical observations were supplemented by histopathological examination of liver and kidney section. The antidiabetic and antioxidant effects of THC are more potent than those of curcumin at the same dose. Results of the present study indicated that THC showed antioxidant effect in addition to its antidiabetic effect in type 2 diabetic rats.     

Antihyperlipidemic effect of D-pinitol on streptozotocin-induced diabetic Wistar rats

D-pinitol (3-O-methyl-chiroinositol), an active principle of the traditional antidiabetic plant, Bougainvillea spectabilis, is claimed to exert insulin-like effects. This study was undertaken to evaluate the effect of D-pinitol on lipids and lipoproteins in streptozotocin (STZ)-induced diabetic Wistar rats. Rats were made type II diabetic by single intraperitoneal injection of STZ at a dose of 40 mg/kg body weight. STZ-induced diabetic rats showed significant (p < 0.05) increase in the levels of blood glucose and total cholesterol, triglycerides, free fatty acids, and phospholipids in serum, liver, kidney, heart, and brain. The levels of low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) cholesterol were significantly increased, and the level of high-density lipoprotein (HDL) cholesterol was significantly decreased in diabetic rats Oral administration of D-pinitol to STZ-induced diabetic rats showed significant (p < 0.05) decrease in the levels of blood glucose and total cholesterol, triglycerides, free fatty acids, and phospholipids in serum, liver, kidney, heart, and brain. The D-pinitol also lowered significantly (p < 0.05) LDL and VLDL cholesterol levels and increased significantly (p < 0.05) HDL cholesterol levels in the serum of diabetic rats. Thus, the present study clearly showed the antihyperlipidemic effect of D-pinitol in STZ-induced type II diabetic rats.     

Metabolomic analysis of amino acid and energy metabolism in rats supplemented with chlorogenic acid

This study was conducted to investigate effects of chlorogenic acid (CGA) supplementation on serum and hepatic metabolomes in rats. Rats received daily intragastric administration of either CGA (60 mg/kg body weight) or distilled water (control) for 4 weeks. Growth performance, serum biochemical profiles, and hepatic morphology were measured. Additionally, serum and liver tissue extracts were analyzed for metabolomes by high-resolution ¹H nuclear magnetic resonance-based metabolomics and multivariate statistics. CGA did not affect rat growth performance, serum biochemical profiles, or hepatic morphology. However, supplementation with CGA decreased serum concentrations of lactate, pyruvate, succinate, citrate, β-hydroxybutyrate and acetoacetate, while increasing serum concentrations of glycine and hepatic concentrations of glutathione. These results suggest that CGA supplementation results in perturbation of energy and amino acid metabolism in rats. We suggest that glycine and glutathione in serum may be useful biomarkers for biological properties of CGA on nitrogen metabolism in vivo.     

Protection against the diabetogenic effect of feeding tert-butylhydroquinone to rats prior to the administration of streptozotocin

We determined whether an oral administration of the synthetic antioxidant, tert-butylhydroquinone (TBHQ), or the naturally occurring lipoxygenase inhibitor, curcumin, to rats would provide protection against the diabetogenic effect of streptozotocin (STZ). Male Sprague-Dawley rats were fed on an AIN-76-based purified diet containing 0.0028% TBHQ or on the purified diet with a daily intragastric administration of curcumin (200 mg/kg of body weight) for one week while receiving intravenously administered STZ. The rats fed on the TBHQ-containing diet were resistant to diabetes development when compared with the rats fed on the TBHQ-free diet and had a higher body weight gain and lower serum glucose concentration. Glucose-stimulated insulin secretion from the pancreatic islet in the rats that had received TBHQ was higher than that in the control rats. The rats receiving curcumin showed no beneficial effect on these diabetic symptoms. These findings provide direct evidence for the suggestion that dietary supplementation of an antioxidant may exert a preventive effect on the diabetogenic action of free-radical producers.     

Antihyperlipidemic and antidiabetic effects of umbelliferone in streptozotocin diabetic rats

The aim of the study was to evaluate blood glucose and lipid lowering effects of Umbelliferone (UMB) in streptozotocin (STZ) diabetic rats. Male albino Wistar rats (180 to 200 g) were induced diabetes by administration of STZ (40 mg/kg) intraperitonially. Normal and diabetic rats were treated with UMB in 10 percent dimethyl sulfoxide (DMSO) for 45 days. Diabetic rats had increased plasma glucose and decreased insulin, total proteins (TP), and albumin in addition to decreased food intake and body weight. Elevation in total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), triglycerides (TG), free fatty acids (FFA), and phospholipids (PL), and reduction in high density lipoprotein cholesterol (HDL-C) in the plasma were observed. Liver and kidney tissues of diabetic rats had elevation in the levels of TC, TG, FFA, and PL. Treatment with UMB decreased plasma glucose and increased insulin, TP, and albumin apart from food intake and body weight. In UMB-treated diabetic rats, plasma and tissue TC, TG, PL and FFA, and plasma LDL-C, VLDL-C, and HDL-C reversed to near normal. Thus, reduction of blood glucose and lipid profiles indicates that UMB has antidiabetic and antihyperlipidemic effects in diabetic rats.     

Resistance of cats to the diabetogenic effect of alloxan

Experimental diabetes mellitus can be induced chemically in many species of animals with streptozotocin or alloxan. However, the cat is known to be resistant to the diabetogenic effect of streptozotocin. The purpose of this study was to find the optimal dose and rate of injection of alloxan to consistently produce hyperglycemia (blood sugar levels greater than 300 mg/dl) in cats. Alloxan was administered to 22 cats at various concentrations (50, 100 and 150 mg/kg) and different rates of injection (0.5, 1.0 and 1.5 ml/min). No hyperglycemic effect was observed at any of the concentrations or different rates of injection. Cats receiving high concentrations and/or high rates of injection of alloxan died due to kidney damage. The results of this study suggest that the cat is resistant to the diabetogenic effect of alloxan, but is susceptible to its toxic side effects.     

Protective effect of adonitol on lactic acid bacteria subjected to freeze-drying

The protective effects of glycerol, adonitol, and four other related polyhydric alcohols on lactic acid bacteria subjected to freeze-drying were examined. The presence of adonitol in the suspending medium markedly protected the viabilities of the 12 stains tested. Dulcitol, mannitol, m-inositol, and sorbitol were found to provide little or no protection.     

Role of chlorogenic acid quinone and interaction of chlorogenic acid quinone and catechins in the enzymatic browning of apple

Chlorogenic acid (CQA) is one of the major polyphenols in apple and a good substrate for the polyphenol oxidase (PPO) in apple. Apple contains catechins as well as CQA, and the role of CQA quinone and its interaction with catechins in the enzymatic browning of apple were examined. Browning was repressed and 2-cysteinyl-CQA was formed when cysteine was added to apple juice. CQA quinone was essential for browning to occur. Although catechins and CQA were oxidized by PPO, some catechins seemed to be non-enzymatically oxidized by CQA quinone.     

Caffeic acid phenethyl ester ameliorates cerebral infarction in rats subjected to focal cerebral ischemia

The effects of caffeic acid phenethyl ester (CAPE), an antioxidant derived from propolis, on the infarct volume elicited by focal cerebral ischemia were studied on Long-Evans rats. Cerebral infarction was induced by microsurgical procedures with ligation of the right middle cerebral artery (MCA) and clipping of bilateral common carotid arteries (CCA) for 60 min. The rats were sacrificed 24 h later and serial brain slices of 2 mm thickness were taken and stained for the measurement of infarct area. CAPE was administered intravenously 15 min before MCA occlusion. Pretreatment of CAPE (0.1, 1 and 10 microg/kg) significantly reduced the total infarct volume from 169.6 +/- 14.5 mm3 (control) to 61.0 +/- 24.1 mm3 (0.1 microg/kg CAPE), 47.4 +/- 9.1 mm3 (1 microg/kg CAPE), and 42.4 +/- 8.7 mm3 (10 microg/kg CAPE), respectively. Plasma nitric oxide (NO) content was significantly increased in rats subjected to focal cerebral ischemia. It is concluded that CAPE possesses neuroprotective properties in focal cerebral ischemia injury in rats possibly through its antioxidant effect and/or via the upregulation of NO production.     

Chain elongation and desaturation of palmitic acid in liver microsomes of rats subjected to hyperbaric exposure.

The enzyme activities associated with chain elongation and desaturation of fatty acid in hepatic microsomes from rats held at 1 ATA of air, 1 ATA of He-O2, and 20 ATA of He-O2 were studied. It was found that both the microsomal chain elongation and desaturation of fatty acids were depressed in rats held at 1 ATA of He-O2 as compared to animals held at 1 ATA of air. When animals were exposed to an environment of 20 ATA of He-O2, the chain elongation of fatty acid was about the same as for rats held at 1 ATA of air and was two times greater than for the rats held at 1 ATA of He-O2. The desaturase activity was depressed as compared to the two groups of control animals held at 1 ATA of air and 1 ATA of He-O2.     

Protective effect of exogenous coenzyme Q in rats subjected to partial hepatic ischemia and reperfusion.

In a surgical model of liver ischemia lipid peroxidation occurs, as shown by increase of lipid peroxidation end products, endogenous CoQ9 is oxidized and mitochondrial respiration is lowered; however, pre-treatment of the rats by i.p. injection of CoQ10 for 14 days normalizes the above parameters, presumably by way of the observed high extent of reduction of the incorporated quinone; moreover, liver homogenates of the CoQ10-treated rats are more resistant than those of non-treated rats to oxidative stress induced by an azido free radical initiator. This preliminary study suggests that CoQ10 pre-treatment can be of beneficial effect against oxidative damage during liver surgery transplantation.