Periandavan Kalaiselvi

Attenuation of senescence-induced oxidative exacerbations in aged rat brain by (-)-epigallocatechin-3-gallate.

Aging is a complex biological phenomenon which involves free radicals and oxidative stress. Brain is more susceptible and vulnerable to oxidative damage due to its high‐polyunsaturated fatty acid content and high rate of aerobic metabolism. Since the antioxidant defense system is diminished during aging, antioxidant supplementation might be a protective strategy against age‐associated oxidative damage. The present study evaluates the antioxidant potential of (−)‐epigallocatechin‐3‐gallate (EGCG), a major polyphenol present in green tea against age‐associated oxidative damage in rat brain. Male albino rats of Wistar strain were used in the study. Group I (young) and Group II (aged) rats received saline alone orally for 30 days. Group III (young) and Group IV (aged) rats received EGCG (2 mg/kg body weight/day) orally for 30 days. Antioxidant status and oxidative damage were assessed. EGCG brought about an augmentation in the activities of enzymic antioxidants like superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose‐6‐phosphate dehydrogenase and improved the non‐enzymic antioxidants like tocopherol, ascorbic acid and glutathione. EGCG ameliorated the malondialdehyde and protein carbonyl levels. Thus, EGCG has emerged out as a good antioxidant neutraceutical and a neuroprotective agent in alleviating the age‐associated oxidative damage in aged rat brain.

Repletion of antioxidant status by EGCG and retardation of oxidative damage induced macromolecular anomalies in aged rats.

Ageing is defined as the loss of ability to maintain cellular homeostasis of an organism associated with the free radical-elicited oxidative damage to cellular macromolecules. The aim of this study was to evaluate the efficacy of epigallocatechin-3-gallate (EGCG), the key component of green tea catechins on attenuating the age associated oxidative perturbances by assessing the redox status in mitotic (liver) and post-mitotic (skeletal muscle) tissues of young and aged rats. From the results, we observed an increase in the marker for oxidative damage such as lipid peroxidation and protein carbonyl content in aged rats, when compared to young rats. This was accompanied with decreased levels of both enzymic and non-enzymic antioxidants and redox index. On supplementation with EGCG (100 mg/kg body weight by oral gavage for 30 days), the levels of lipid peroxidation and protein carbonyl content were significantly decreased in aged rats, possibly by enhancing the GSH redox status, and both enzymic and non-enzymic antioxidants status. In conclusion, this study supports the beneficial effect of EGCG in alleviating oxidative disturbances in ageing and retard the age associated derangements in both mitotic and post-mitotic tissues.

Mitochondrial alterations in aging rat brain: effective role of ( )-epigallo catechin gallate

Aging is a multi‐factorial process which involves deprivation in bodys metabolism. Brain mitochondria are prone to oxidative damage owing to their high metabolic rate. The decline in antioxidant system during aging augments the neuronal damage to mitochondrial components like antioxidant system, Krebs cycle enzymes and electron transport chain complexes. Since brain is an organ rich in fatty acids, lipid peroxidation products like hydroxynonenal are predominant. Those lipid peroxidation products conjugate with amino acids to form adducts which alter their structural and functional properties. Epigallo catechin gallate is a potent antioxidant which is rich in green tea extract. This study elucidated the antioxidant potential of epigallo catechin gallate to counteract the mitochondrial oxidative damage in brain. The study comprised of young (3–4 months old; 150 ± 20 g) and aged (above 24 months; 420 ± 20 g) male albino rats of Wistar strain in Groups I and II. Groups III and IV comprised of young and aged rats supplemented with epigallo catechin gallate (2 mg/kg body weight) for 30 days. Antioxidants, Krebs cycle enzymes and electron transport chain complexes were assayed in the mitochondrial fraction. Hydroxynonenal expression was carried out using immunohistochemical analysis. Epigallo catechin gallate supplementation decreased the expression of hydroxynonenal in aged brain, up‐regulated the antioxidant system and augmented the activities of Krebs cycle enzymes and electron transport chain complexes in aged brain mitochondria thus proving its antioxidant potential at the level of mitochondria.

Senescence mediated redox imbalance in cardiac tissue: Antioxidant rejuvenating potential of green tea extract

OBJECTIVE The activities and capacities of antioxidant systems of tissue cells are declined during aging, leading to the gradual loss of pro-oxidant/antioxidant balance and accumulation of oxidative damage. Hence, the present study evaluated the role of green tea extract (GTE), rich in polyphenols, in combating age-associated macromolecular damage in rat cardiac tissue. METHODS The antioxidant defense system, lipid peroxidation, protein oxidation, and redox status in heart tissue were studied using young and aged rats. RESULTS Significant increases in lipid peroxidation, protein carbonyls, and marked decreases in glutathione redox status, protein thiols, and activities of enzymatic and non-enzymatic antioxidants were observed in aged rats compared with young rats. Supplementation of GTE (100 mg/kg of body weight per day) orally for 30 days ameliorated these changes significantly. CONCLUSION This study accredits GTEs antioxidant rejuvenating potency and its role in the amelioration of senescence-mediated redox imbalance in aged rat cardiac tissue.

A novel basic protein from human kidney which inhibits calcium oxalate crystal growth

Objectives To isolate calcium oxalate‐binding proteins from human kidney and characterize the functional properties.

Impact of epigallo catechin-3-gallate on acetylcholine-acetylcholine esterase cycle in aged rat brain.

Neurotransmission plays an important role in communication of messages in brain. Cholinergic alterations during aging are associated with learning and memory. Neurotransmitters and enzymes that influence these neurotransmitters are significant in age-associated memory. Neurotransmitters like acetylcholine, serotonin and dopamine levels were studied. Kinetics of acetylcholine esterase was studied. There was an alteration in km and Vm values which was brought back to near-normalcy by EGCG. Behavioural changes were assessed by radial maze experiment. EGCG, a good neuroprotective drug proved to alleviate the behavioural alterations in aged rat brain. Acetylcholine esterase was partially purified from rat brain and assayed in vitro. Several modifiers like EGCG and donepezil were added in silico and the activity of the enzyme was calculated. EGCG increased the activity when compared to negative control, donepezil. Using bioinformatics tools EGCG, acetylcholine and donepezil were docked with acetylcholine esterase. EGCG formed a good docking-complex with the enzyme. Thus, it shall be hypothesized that the neuroprotective activity of EGCG might be due to its influence on cholinergic neurotransmission thereby improving the cognitive functions of the brain.

Counteracting adriamycin-induced oxidative stress by administration of N-acetyl cysteine and vitamin E

Abstract Adriamycin (ADR), a cytotoxic antineoplastic drug, is used in the treatment of various solid tumors. However, its efficacy continues to be challenged by significant toxicities including nephrotoxicity. In the present study, the effects of N-acetyl cysteine (NAC) and vitamin E, known antioxidants, were investigated on ADR-induced peroxidative damage in rat kidney. Adult male albino rats of Wistar strain were administered ADR as a single dose (10mg/kg body weight, i.v.). Histopathological studies indicated that ADR-treated kidney sections show focal tubular necrosis and casts. ADR-injected rats showed a significant decline in the activities/levels of enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione-S-transferase) and non-enzymic antioxidants (thiols, vitamin C and vitamin E) with high malondialdehyde levels. The extent of nephrotoxicity was evident from the increased activities of urinary marker enzymes (alkaline phosphatase, lactate dehydrogenase and γ-glutamyltransferase). Treatment with NAC and vitamin E (50mg/kg b.w., i.p.) 1day prior to ADR administration maintained near normal activities of the enzymes, significantly reduced lipid peroxidation and prevented the necrosis caused by ADR, thereby proving to be an effective thiol replenishing agent and antioxidant.

Attenuation of the inflammatory changes and lipid anomalies by epigallocatechin-3-gallate in hypercholesterolemic diet fed aged rats

Epidemiological studies suggest that even in the absence of other risk factors advanced age itself significantly increases cardiovascular morbidity. Age aggravated inflammatory activity further plays a central role in the pathogenesis of atherosclerosis and its complications. EGCG, a major flavonoid present in green tea extract has been proved to be useful in lowering cholesterol levels thereby slowing down the progression of cardiovascular diseases in young animals. Thus, the endeavor of this study was to assess the impact of high-cholesterol diet on aging and vice versa and to exploit the potential of EGCG to combat age-associated hypercholesterolemia and mitigate inflammation. Male albino rats of Wistar strain (3 months-young and 24 months old-aged) were used in this study. Hypercholesterolemia was induced by the diet comprising of the normal rat chow supplemented with 4% cholesterol and 1% cholic acid. EGCG (100 mg/kg body weight/day) was given orally for 30 days. The results revealed abnormally elevated lipid levels, marker enzymes and inflammatory markers in serum of aged hypercholesterolemic rats when compared to young hypercholesterolemic rats, while treatment with EGCG partially reversed these aberrations. The present work demonstrates the inflammatory responses in hypercholesterolemic atherogenesis during aging and further underscores the salubrious role played by the EGCG in attenuating the inflammatory and lipid anomalies.

Studies on Calcium Oxalate Binding Proteins: Effect of Lipid Peroxidation

Objective: Urolithiasis and free radicals have long been associated. In this study, we have isolated calcium oxalate monohydrate (COM) binding proteins from rat kidney before and after lipid peroxidation (LPO) and studied its properties on calcium oxalate crystal growth. Materials and Methods: LPO was carried out using t-butyl hydroperoxide, cumene hydroperoxide and an ascorbate system. The COM binding proteins from control and peroxidised tissues were isolated using a modified procedure. Protein was extracted using 25 mM EDTA, and the extract was loaded onto a DEAE cellulose column and eluted with Tris-HCl buffer (pH 6.5), 0.05 M NaCl in the above buffer and 0.3 M NaCl in the same buffer. Three major protein fractions were obtained, and they were designated as fractions I, II and III according to their order of elution. The proteins were subjected to calcium oxalate crystal nucleation and aggregation. Results: A positive correlation was observed between LPO and COM adsorption, while a negative correlation was observed between reduced glutathione and COM adsorption. Peroxidised protein did not show any alteration in the elution profile on the DEAE cellulose column. The –SH content of the peroxidised fractions were lower than that of the control fractions, but their oxalate binding activities were increased. Peroxidised fraction I promoted crystal growth to a greater extent than the control fraction I. Peroxidised fractions II and III were less inhibitory in nature compared to their control fractions. Light-microscopic examination of the crystals formed in the presence of the peroxidised fractions showed the formation of large aggregates of COM. Conclusion: Peroxidation of the renal proteins favoured their adsorption to COM crystals. –SH depletion increased the oxalate binding activity and also their affinity to the COM crystals. The peroxidised fraction I was found to favour the formation of large aggregates, suggesting that peroxidation may be one of the mechanisms altering the crystal inhibitory activity of the proteins in hyperoxaluria.

Neuroprotective potential of epigallo catechin-3-gallate in PC-12 cells

Oxidative stress is a major player in aging and neurodegenerative disorders. Macromolecular damage occurs as a result of oxidative stress that affects the mitochondria. Mitochondrial damage leads to cell death by apoptosis or necrosis. EGCG is a tea polyphenol that protects the cells against oxidative stress. Neuroprotective potential of EGCG was tested against H2O2 induced oxidative stress in PC-12 cells. PC-12 cells were grown in tissue culture flasks. Oxidative stress was induced by adding H2O2 to the cells. EGCG was also added and the cell death was assessed using MTT assay. Oxidative stress was assessed by protein carbonyl and thiol status. Mitochondrial membrane potential was studied using JC-1 staining. TNF-α levels were assessed using ELISA. H2O2 increased the protein carbonyl content and reduced the thiol status in the PC-12 cells. Cell death was increased in H2O2 treated cells as shown by MTT assay. Mitochondrial membrane potential was also decreased along with increase in TNF-α level in H2O2 treated cells. EGCG brought about an increase in the cellular thiol status and decreased the protein carbonyl content in the PC-12 cells. Cell death was attenuated by EGCG treatment along with an increase in mitochondrial membrane potential and decrease in TNF-α level. EGCG conferred its antioxidant potential to PC-12 cells as evident by decreased protein damage. Mitochondrial membrane potential was improved along with a decrement in the cell death in PC-12 cells. EGCG acts as a good neutraceutical antioxidant to render neuroprotectivity to PC-12 cells.