Identification of a peptide ligand recognizing dysfunctional endothelial cells for targeting atherosclerosis.

Targeting ligands to dysfunctional or activated endothelial cells overlying atherosclerotic plaques could provide tools for selective drug delivery to atherosclerotic lesions. To identify peptides selectively targeting dysfunctional endothelial cells, a phage library was screened against tumor necrosis factor-alpha (TNF-alpha) activated bovine aortic endothelial cells (BAECs). Five rounds of biopanning were carried out and the phage clones selected were examined for their DNA inserts. A phage clone displaying the CLWTVGGGC sequence occurred most frequently and was found to bind specifically to TNF-alpha activated BAECs over untreated cells. On the other hand, bindings of the phage clone to human umbilical vein endothelial cells, lymphatic endothelial cells, and epithelial cells were minimal. Flow cytometric and fluorescence microscopic studies showed the preferential binding of the CLWTVGGGC peptide to TNF-alpha activated BAECs compared to untreated cells. In vivo studies demonstrated selective homing and co-localization of the CLWTVGGGC peptide to dysfunctional endothelial cells overlying atherosclerotic plaques in low-density lipoprotein receptor-deficient mice. These results demonstrate that the CLWTVGGGC peptide could specifically recognize dysfunctional endothelial cells at atherosclerotic plaques and be used as a targeting ligand for drug delivery and imaging of atherosclerosis.

Modulatory role of grape seed extract on age-related oxidative DNA damage in central nervous system of rats.

Aging is the accumulation of diverse deleterious changes in the cells and tissues leading to increased risk of diseases. Oxidative stress is considered as a major risk factor and contributes to age related increase in DNA oxidation and DNA protein cross-links in central nervous system during aging. In the present study, we have evaluated the salubrious role of grape seed extract on accumulation of oxidative DNA damage products such as 8-OHdG and DNA protein cross-links in aged rats. Male albino rats of Wistar strain were divided into four groups: Group I, young control rats; Group II, young rats treated with grape seed extract (100 mg/kg b.wt.) for 30 days; Group III, aged control rats; Group IV, aged rats supplemented with grape seed extract (100 mg/kg b.wt.) for 30 days. Our results, thus, revealed that grape seed extract has inhibiting effect on the accumulation of age-related oxidative DNA damages in spinal cord and in various brain regions such as cerebral cortex, striatum and hippocampus.

Age associated changes in erythrocyte membrane surface charge: Modulatory role of grape seed proanthocyanidins.

Aging, a multifactorial process of enormous complexity is characterized by impairment of physio-chemical and biological aspects of cellular functions. It is closely associated with increased free radical production, which situation ultimately leads to devastation of normal cell function and membrane integrity. The present study was aimed to determine the effect of proanthocyanidins rich grape seed extract (GSP) on membrane surface charge density in erythrocytes during animal age associated oxidative stress. GSP (100 mg/day/kg body weight) was administered orally for 15 and 30 days to young and aged rats. Significant decrease in surface charge levels with concomitant increase in protein carbonyls and decrease in glycoprotein, antioxidants status was noted in erythrocytes of aged rats when compared with young rat erythrocytes. Duration dependent supplementation of GSP increased the erythrocyte surface charge density to near normalcy in aged rats. Decrease in protein carbonyls level and increase in glycoproteins as well as antioxidant status was observed in aged rat erythrocytes on GSP treatment. Thus, from our results, we conclude that GSP is an effective anti-aging drug in preventing the oxidative stress associated loss of membrane surface charge, which thereby maintains the erythrocyte membrane integrity and functions in elderly.

Age-related oxidative protein damages in central nervous system of rats: modulatory role of grape seed extract.

Oxidative stress has been shown to play a major role in aging and in neurodegenerative disorders. Protein modification is one of the important consequences of oxidative stress. In the present study, we evaluated the role of grape seed extract on memory, reactive oxygen species production, protein carbonyls (PCO), and thiol status in discrete regions of central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I--control young rats, Group II--young rats treated with grape seed extract (100 mg/kg BW) for 30 days, Group III--aged control rats and Group IV-aged rats supplemented with grape seed extract (100 mg/kg BW) for 30 days. Memory loss was observed in the aged rats. Age associated increase in reactive oxygen species production and protein oxidation was observed in the spinal cord; cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). The levels of total thiol, non-protein thiol, protein thiols were found to be significantly decreased in spinal cord and all the brain regions studied in aged rats when compared to young rats. Supplementation of aged rats with grape seed extract showed increased memory performance and declined reactive oxygen species production, decreased protein carbonyl levels and improved thiol levels. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical induced protein oxidation in aged rats thereby protecting the central nervous system from the reactive oxygen species.

Rejuvenation of antioxidant system in central nervous system of aged rats by grape seed extract.

Oxidative stress is considered as a major risk factor that contributes to age-related increase in lipid peroxidation and declined antioxidants in the central nervous system during aging. Grape seed extract, one of the bioflavonoid, is widely used for its medicinal properties. In the present study, we evaluated the role of grape seed extract on lipid peroxidation and antioxidant status in discrete regions of the central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I-control young rats, Group II-young rats treated with grape seed extract (100 mg/kg body weight) for 30 days, Group III-aged control rats and Group IV-aged rats supplemented with grape seed extract (100 mg/kg body weight) for 30 days. Age-associated increase in lipid peroxidation was observed in the spinal cord, cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). Activities of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase and levels of non-enzymic antioxidants like reduced glutathione, Vitamin C and Vitamin E were found to be significantly decreased in all the brain regions studied in aged rats when compared to young rats. However, normalized lipid peroxidation and antioxidant defenses were reported in the grape seed extract-supplemented aged rats. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in the central nervous system of aged rats.

Modulation of age-associated oxidative DNA damage in rat brain cerebral cortex, striatum and hippocampus by L-carnitine.

The free radical theory of cell aging may have significant relevance in the pathogenesis of a number of age-related neurological disorders. A large body of experimental evidence supports the existence of a relationship between genomic instability, DNA damage and aging. The age-associated accumulation of oxidative DNA damage is well documented in central nervous system. The decline of mitochondrial respiratory function and loss of normal cellular homeostasis as consequences of excessive accumulation of endogenous oxidative damages to DNA have long been indicated in the aging process. In the present study, age-associated alterations in the content of DNA and accumulation of oxidative DNA damage products such as 8-OHdG and DNA protein cross-links are mainly focused. In parallel, we have also investigated the salubrious effect of l-carnitine against oxidative DNA damage as it possesses energy and antioxidant improving properties. Our results thus reveal that L-carnitine has inhibiting effect on the accumulation of age-related oxidative DNA damage in various brain regions, viz. cerebral cortex, striatum and hippocampus.

Age-dependent alterations in mitochondrial enzymes in cortex, striatum and hippocampus of rat brain -- potential role of L-Carnitine.

Mitochondria link the energy -- releasing activities of electron transport and proton pumping with the energy conserving process of oxidative phosphorylation to form ATP. A declined mitochondrial performance has been generally observed during aging. In the present investigation, the activities of tricarboxylic acid cycle enzymes such as isocitrate, alpha-ketoglutarate, succinate and malate dehydrogenases and electron transport complexes I-IV were measured in mitochondria isolated from brain regions like cortex, striatum and hippocampus of young and aged rats before and after L-Carnitine supplementation. All the three brain regions of aged rats showed decreased activities of isocitrate, alpha-ketoglutarate and succinate dehydrogenases, complexes I and IV when compared to control young rats. Striatum seems to be the most susceptible region when compared to hippocampus and cortex. L-Carnitine supplementation to aged rats reversed the activities of these enzymes to near normal whereas treatment to young rats did not show any significant alterations. These results confirm that L-Carnitine can alleviate the age-associated decline in the metabolic efficiency of mitochondria in all three brain regions under investigation.