Antioxidant Effects Of Curcumin Research Articles

Curcumin protects against ischemia/reperfusion injury in rat kidneys

Renal ischemia followed by reperfusion leads to acute renal failure in both native kidneys and renal allograft. We investigated the effect of curcumin on ischemia-reperfusion (I/R) injury and the antioxidant effects of curcumin in rats. Thirty rats were randomly divided into five experimental groups (control, sham, curcumin, I/R and I/R+curcumin, n=6 each). Curcumin was administered (200 mg kg(-1)) orally to curcumin and I/R+curcumin groups for 7 days. Then, the rats were subjected to bilateral renal ischemia for 45 min and followed by reperfusion for 24 h. All rats were killed and kidney function tests, serum and tissue nitric oxide (NO), protein carbonyl (PC), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were determined. Histopathological examinations were also performed. Curcumin significantly improved the urea and cystatin C levels in I/R+curcumin group compared to I/R group (p<0.05). Reduction of serum GSH-Px was significantly improved by curcumin (p<0.001), but SOD enzyme activity did not alter (p>0.05). Treatment with curcumin also resulted in significant reduction in serum and tissue MDA, NO and PC and for tissue that were increased by renal I/R injury (p<0.001 for serum and p<0.05 for tissue, respectively). In histological examination, the rats treated with curcumin had nearly normal morphology of the kidney. Based on our results, it can be concluded that curcumin protects the kidneys against I/R injury via its antioxidant effects.

Hypolipidemic and antioxidant effects of curcumin and capsaicin in high-fat-fed rats

The beneficial hypolipidemic and antioxidant influences of the dietary spice compounds curcumin and capsaicin were evaluated. Curcumin, capsaicin, or their combination were included in the diet of high-(30%)-fat-fed rats for 8 weeks. Dietary high-fat-induced hypertriglyceridemia was countered by dietary curcumin, capsaicin, or their combination by 12%-20%. Curcumin, capsaicin, and their combination also produced a slight decrease in serum total cholesterol in these animals. Serum alpha-tocopherol content was increased by dietary curcumin, capsaicin, and their combination in high-fat-fed rats. Serum total thiol content in high-fat-fed animals and serum ascorbic acid in normal animals was elevated by the combination of curcumin and capsaicin. Hepatic glutathione was increased by curcumin, capsaicin, or their combination in normal animals. Hepatic glutathione and alpha-tocopherol were increased, whereas lipid peroxide level was reduced by dietary curcumin and combination of curcumin and capsaicin in high-fat-fed animals. Serum glutathione peroxidase and glutathione transferase in high-fat-fed rats were generally higher as a result of dietary curcumin, capsaicin, and the combination of curcumin and capsaicin. Hepatic glutathione reductase and glutathione peroxidase were significantly elevated by dietary spice principles in high-fat-fed animals. The additive effect of the 2 bioactive compounds was generally not evident with respect to hypolipidemic or antioxidant potential. However, the effectiveness of the combination was higher in a few instances.

Curcumin and its analogues as potent inhibitors of low density lipoprotein oxidation: H-atom abstraction from the phenolic groups and possible involvement of the 4-hydroxy-3-methoxyphenyl groups

Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, 1) is a yellow ingredient isolated from turmeric ( Curcumin longa). It has been shown to exhibit a variety of biological activities including antioxidative activity. In order to find more active antioxidants with 1 as the lead compound we synthesized curcumin analogues, i.e., 1,7-bis(3,4-dihydroxyphenyl)-1,6-heptadiene-3,5-dione ( 2), 1-(3,4-dihydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione ( 3), 1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)-1,6-heptadiene-3,5-dione ( 4), 1,7-bis (4-hydroxyphenyl)-1,6-heptadiene-3,5-dione ( 5), 1-(3,4-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione ( 6), 1,7-bis(3,4-dimethoxyphenyl)-1,6- heptadiene-3,5-dione ( 7), 1,7-bis(4-methoxyphenyl)-1,6-heptadiene-3,5-dione ( 8), and 1,7-diphenyl-1,6-heptadiene-3,5-dione ( 9). Antioxidative effects of curcumin and its analogues against free radical initiated peroxidation of human low density lipoprotein (LDL) were studied. The peroxidation was initiated either by a water-soluble initiator 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH), or by cupric ion (Cu 2+). The reaction kinetics were monitored either by the uptake of oxygen and the depletion of α-tocopherol present in the native LDL, or by the formation of thiobarbituric acid reactive substances. Kinetic analysis of the antioxidation process demonstrates that these compounds, except 7, 8, and 9, are effective antioxidants against AAPH- and Cu 2+-initiated LDL peroxidation by H-atom abstraction from the phenolic groups. Compounds 2 and 3 which bear ortho-diphenoxyl functionality possess significantly higher antioxidant activity than curcumin and other analogues, and the 4-hydroxy-3-methoxyphenyl group also play an important role in the antioxidative activity.

The relationship between the anti-inflammatory effects of curcumin and cellular glutathione content in myelomonocytic cells

Oxidative stress plays an important role during inflammatory diseases and recent therapies have focused on antioxidant administration to diminish oxidative stress and to arrest inflammatory processes. In this study, we investigated the impact of the GSH modulating effects of curcumin, a naturally derived polyphenol, on inflammatory processes in myelomonocytic U937 cells. One hour after administration of 10 μmol/l curcumin reactive oxygen species (ROS) production was significantly increased in undifferentiated U937 cells (+43%). Twenty-four hour after addition of curcumin, a significantly decreased ROS concentration was found (−32%), whereas GSH (+110%) and GSSG (+88%) content increased. A higher concentration of curcumin (25 μmol/l) caused an even stronger increase of GSH (+145%) and GSSG (+101%), but significantly decreased percentage of living cells to 84%. The increased GSH content of differentiated U937 cells after pre-incubation with curcumin was associated with lowered ROS production, nuclear factor kappa B (NFκB) activation (−34%) and tumor necrosis factor alpha (TNF-α) secretion (−51%) after LPS exposure. Curcumin inhibited TNF-α formation was also seen after GSH depletion by buthionine sulfoximine (BSO). This study shows that the antioxidative effects of curcumin are preceded by an oxidative stimulus, which is time and dose-dependent. Excessive concentrations of curcumin may even harm cells, as cell viability was decreased, in spite of elevated GSH contents. There was no clear relationship between intracellular GSH concentrations and the anti-inflammatory effects of curcumin.

The spice of life for cystic fibrosis

The spice of life for cystic fibrosis

Spices as influencers of body metabolism: an overview of three decades of research

The safety of the consumption of spices – turmeric, red pepper and black pepper and their respective active principles was established in animal studies by observing the influence on growth, organ weights, nitrogen balance and blood constituents upon feeding at levels close to human intake as well as upto 100-times the normal human intake. Exhaustive animal studies documented the beneficial influence of turmeric/curcumin, red pepper/capsaicin, and garlic on lipid metabolism, especially anti-hypercholesterolemic effect of the three spices and anti-lithogenic effect of curcumin and capsaicin. The anti-diabetic effects of turmeric/curcumin, onion and cumin seeds were also evidenced with particular ameliorative influence of curcumin and onion on diabetic nephropathy. The antioxidant effects of curcumin (of turmeric), capsaicin (of red pepper) and eugenol (of clove) were evidenced both in in vitro and in vivo systems and the consequential health beneficial anti-inflammatory influence in experimentally induced arthritis was documented. The mechanism of digestive stimulant action of common spices examined in experimental animals revealed to be mediated through phenomenal stimulation of bile secretion with an enhanced bile acid concentration (ingredients essential for fat digestion and absorption) and an appropriate stimulation of the activities of digestive enzymes of pancreas and small intestine. The protective influence of hypolipidemic spices – curcumin, capsaicin and garlic on the altered fluidity of erythrocytes under hypercholesterolemic situation was evidenced in experimental animal models. Antioxidant spices were also shown to greatly reduce LDL-oxidation and also modulate the synthesis of prostaglandins and leukotrienes. Several spices or their extracts were also found to beneficially inhibit platelet aggregation. All these observations strongly indicate that many spices and their active principles are excellent nutraceuticals.

Protective effects of curcumin against oxidative damage on skin cells in vitro: its implication for wound healing.

Curcumin, isolated from turmeric, has been known to possess many pharmacologic properties. It has been proven to exhibit remarkable anticarcinogenic, anti-inflammatory, and antioxidant properties. Turmeric curcumin may be a good potential agent for wound healing. To further understand its therapeutic mechanisms on wound healing, the antioxidant effects of curcumin on hydrogen peroxide (H2O2) and hypoxanthine-xanthine oxidase induced damage to cultured human keratinocytes and fibroblasts were investigated. Cell viability was assessed by colorimetric assay and quantification of lactate dehydrogenase release. Exposure of human keratinocytes to curcumin at 10 microg/mL showed significant protective effect against hydrogen peroxide. Interestingly, exposure of human dermal fibroblasts to curcumin at 2.5 microg/mL showed significant protective effects against hydrogen peroxide. No protective effects of curcumin on either fibroblasts or keratinocytes against hypoxanthine-xanthine oxidase induced damage were found in our present studies. The findings indicate that curcumin indeed possessed powerful inhibition against hydrogen peroxide damage in human keratinocytes and fibroblasts.