Nishant P. Visavadiya

Sesame as a hypocholesteraemic and antioxidant dietary component.

Purpose of this study was to examine the dose dependant effects of sesame seed powder as a dietary supplement on hypercholesteraemic and oxidative stress conditions in male albino rats. Sesame seed (Sesamum indicum) powder was administered at 5% and 10% dose levels along with either normal or hypercholesteraemic diet for duration of four weeks. Administration of sesame seed powder to hypercholesteraemic rats resulted in a significant decline in plasma, hepatic total lipid and cholesterol levels and, plasma LDL-cholesterol levels with an increase in plasma HDL-cholesterol levels. Further, these animals also showed increased fecal excretion of cholesterol, neutral sterol and bile acid along with increases in hepatic HMG-CoA reductase activity and bile acid content. Additionally sesame seed feeding improved the hepatic antioxidant status (catalase and SOD enzyme activities) with a reduction in lipid peroxidation. No significant changes in lipid and antioxidant profiles occurred in the normocholesteraemic rats administered with sesame seed powder. These beneficial effects of sesame seed on hypercholesteraemic rats appeared to be due to its fiber, sterol, polyphenol and flavonoid content, enhancing the fecal cholesterol excretion and bile acid production and as well as increasing the antioxidant enzyme activities.

Mitochondria-associated microRNAs in rat hippocampus following traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability. However, the molecular events contributing to the pathogenesis are not well understood. Mitochondria serve as the powerhouse of cells, respond to cellular demands and stressors, and play an essential role in cell signaling, differentiation, and survival. There is clear evidence of compromised mitochondrial function following TBI; however, the underlying mechanisms and consequences are not clear. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally, and function as important mediators of neuronal development, synaptic plasticity, and neurodegeneration. Several miRNAs show altered expression following TBI; however, the relevance of mitochondria in these pathways is unknown. Here, we present evidence supporting the association of miRNA with hippocampal mitochondria, as well as changes in mitochondria-associated miRNA expression following a controlled cortical impact (CCI) injury in rats. Specifically, we found that the miRNA processing proteins Argonaute (AGO) and Dicer are present in mitochondria fractions from uninjured rat hippocampus, and immunoprecipitation of AGO associated miRNA from mitochondria suggests the presence of functional RNA-induced silencing complexes. Interestingly, RT-qPCR miRNA array studies revealed that a subset of miRNA is enriched in mitochondria relative to cytoplasm. At 12h following CCI, several miRNAs are significantly altered in hippocampal mitochondria and cytoplasm. In addition, levels of miR-155 and miR-223, both of which play a role in inflammatory processes, are significantly elevated in both cytoplasm and mitochondria. We propose that mitochondria-associated miRNAs may play an important role in regulating the response to TBI.

Ameliorative action of cyanobacterial phycoerythrin on CCl4-induced toxicity in rats

Carbon tetrachloride (CCl(4)) is largely used as solvent in chemical industries. Carbon tetrachloride is also well known for hepatic and renal toxic actions. The in vivo metabolism of carbon tetrachloride to trichloromethyl (CCl(3)) and peroxy trichloromethyl (OOCCl(3)) radicals has been extensively reported to cause acute liver damage like cirrhosis, steatosis and necrosis. We have evaluated protective action of purified cyanobacterial phycoerythrin (C-PE) on carbon tetrachloride-induced hepatic and renal toxicity in male rats. Rats were orally treated with 25 and 50mg/kg BW of C-PE along with CCl(4) (50% CCl(4), 0.5 ml/kg BW, intraperitoneally) for 28 consecutive days. Results demonstrated that C-PE dose-responsively ameliorates CCl(4)-toxicity by significantly decreasing (P<0.05) organs weight, aminotransferases, alkaline phosphatase, glucose, lipid profile, creatinine, uric acid and malondialdehyde (MDA) concentrations with rise in body weight, food intake, hemoglobin, protein, bilirubin and FRAP values. Neither C-PE nor CCl(4) influenced on serum minerals. Hepatic and renal tissues showed significant decline (P<0.05) in malondialdehyde, lipid hydroperoxides and conjugated dienes with rise in SOD, catalase, GPx, GSH, vitamin-E and vitamin-C levels. Presently observed pharmacological effect on CCl(4) toxicity were from tetrapyrrole molecule and to some extent bilirubin biotransformations, as well as metabolic (dietary protein) actions of C-PE.

Evaluation of antioxidant and anti-atherogenic properties of Glycyrrhiza glabra root using in vitro models

The aim of present study was to evaluate antioxidant property of Glycyrrhiza glabra root extracts using in vitro models. The dose-dependent aqueous and ethanolic extracts demonstrated the scavenging activity against nitric oxide (concentration that caused 50% inhibition of nitric oxide radicals [IC50]=72 and 62.1 µg/ml, respectively), superoxide (IC50=64.2 and 38.4 µg/ml, respectively), hydroxyl (IC50=81.9 and 63 µg/ml, respectively), DPPH (IC50=43.6 and 28.3 µg/ml, respectively) and ABTS•+ (IC50=77.3 and 57.2 µg/ml, respectively) radicals. Further, both extracts showed strong reducing power and iron-chelating capacities. In the Fe2+/ascorbate system, both extracts were found to inhibit mitochondrial fraction lipid peroxidation. In copper-catalyzed human serum and low-density lipoprotein oxidation models, both extracts significantly (P<0.05) lengthened the lag phase along with a decline in the oxidation rate, conjugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substance formation. In conclusion, ethanolic extract of G. glabra possess considerable antioxidant activity and protective effect against the human lipoprotein oxidative system.

Cellular and subcellular oxidative stress parameters following severe spinal cord injury

The present study undertook a comprehensive assessment of the acute biochemical oxidative stress parameters in both cellular and, notably, mitochondrial isolates following severe upper lumbar contusion spinal cord injury (SCI) in adult female Sprague Dawley rats. At 24 h post-injury, spinal cord tissue homogenate and mitochondrial fractions were isolated concurrently and assessed for glutathione (GSH) content and production of nitric oxide (NO•), in addition to the presence of oxidative stress markers 3-nitrotyrosine (3-NT), protein carbonyl (PC), 4-hydroxynonenal (4-HNE) and lipid peroxidation (LPO). Moreover, we assessed production of superoxide (O2•-) and hydrogen peroxide (H2O2) in mitochondrial fractions. Quantitative biochemical analyses showed that compared to sham, SCI significantly lowered GSH content accompanied by increased NO• production in both cellular and mitochondrial fractions. SCI also resulted in increased O2•- and H2O2 levels in mitochondrial fractions. Western blot analysis further showed that reactive oxygen/nitrogen species (ROS/RNS) mediated PC and 3-NT production were significantly higher in both fractions after SCI. Conversely, neither 4-HNE levels nor LPO formation were increased at 24 h after injury in either tissue homogenate or mitochondrial fractions. These results indicate that by 24 h post-injury ROS-induced protein oxidation is more prominent compared to lipid oxidation, indicating a critical temporal distinction in secondary pathophysiology that is critical in designing therapeutic approaches to mitigate consequences of oxidative stress.

Ameliorative Effects of Herbal Combinations in Hyperlipidemia

The roots of Glycyrrhiza glabra, Withania somnifera, Asparagus racemosus, and Chlorophytum borivilianum and seeds of Sesamum indicum are ayurvedic medicinal plants used in India to treat several ailments. Our previous studies indicated that these plants possess hypolipidemic and antioxidant potential. The present study was aimed at investigating the composite effects of these plants on hypercholesterolemic rats. Three different combinations (5 gm%, given for four weeks) used in this study effectively reduced plasma and hepatic lipid profiles and increased fecal excretion of cholesterol, neutral sterol, and bile acid along with increasing the hepatic HMG-CoA reductase activity and bile acid content in hypercholesterolemic rats. Further, all three combinations also improved the hepatic antioxidant status (catalase, SOD, and ascorbic acid levels) and plasma total antioxidant capacity with reduced hepatic lipid peroxidation. Overall, combination I had the maximum effect on hypercholesterolemic rats followed by combinations II and III due to varying concentrations of the different classes of phytocomponents.

High Glucose Upregulates Upstream Stimulatory Factor 2 in Human Renal Proximal Tubular Cells through Angiotensin II-Dependent Activation of CREB

Background/Aims: We have previously demonstrated that a transcription factor, upstream stimulatory factor 2 (USF2), regulates glucose-induced thrombospondin 1 expression and transforming growth factor-β activity in mesangial cells, and plays an important role in diabetic glomerulopathy. In this study, we determined whether USF2 expression in renal proximal tubular cells is regulated by glucose and contributes to diabetic tubulointerstitial fibrosis. Methods: Human renal proximal tubular cells (HK-2 cells) were treated with normal- or high-glucose medium for 24 h. After treatment, real-time PCR or immunoblotting was used to determine the expression of USF2 and other components of the renin-angiotensin system in HK-2 cells. Results: High glucose upregulated USF2 expression and increased extracellular matrix accumulation in HK-2 cells; both were inhibited by siRNA-mediated USF2 knockdown. In addition, high glucose stimulated angiotensinogen and renin expression, increased renin activity, and resulted in increased angiotensin II formation. Treatment of HK-2 cells with an angiotensin II receptor 1 (AT1) blocker – losartan – prevented high-glucose-induced USF2 expression and high-glucose-enhanced phosphorylation of CREB (cAMP response element-binding protein). Conclusion: Our data established that high glucose stimulated USF2 expression in HK-2 cells, at least in part, through angiotensin II-AT1-dependent activation of CREB, which can contribute to diabetic tubulointerstitial fibrosis.BACKGROUND Oxidative stress is an important inducer of cell apoptosis and plays a key role in the development of renal inflammation. The prostate apoptosis response factor-4 (Par-4) gene was originally identified in prostate cells undergoing apoptosis. Subsequently, Par-4 was found to possess potent pro-apoptotic activity in various cellular systems. However, it remains unclear whether Par-4 is involved in oxidant injury of renal tubular epithelial cells. AIMS To determine the role of Par-4 in renal proximal tubular cell apoptosis induced by oxidative stress. METHODS Par-4 gene expression was silenced by small interfering RNA. Renal proximal tubular cells were then exposed to hydrogen peroxide and the effect of Par-4 silencing on apoptosis and expression of phosphorylated Akt and vascular endothelial growth factor was determined. RESULTS Hydrogen peroxide induced apoptosis and increased Par-4 expression in human renal proximal tubular epithelial cells. Par-4 silencing significantly protected renal proximal tubular cells from apoptosis via activating the PI3K/Akt signaling pathway as Akt phosphorylation was enhanced. Par-4 silencing also ameliorated the downregulation of vascular endothelial growth factor expression induced by oxidative stress. CONCLUSION Par-4 gene silencing resulted in PI3K/Akt signaling-dependent inhibition of renal proximal tubular cell apoptosis following oxidative stress.

Chlorophytum borivilianum as potential terminator of free radicals in various in vitro oxidation systems.

Chlorophytum borivilianum is a very popular herb in traditional Indian medicine and used as a potent “Rasayana” drug in “Ayurveda” as a rejuvenator. Currently, a large body of evidence supports the key role of free radicals in diverse pathological conditions such as aging and atherosclerosis. The present investigation essentially focuses on the comprehensive account of in vitro antioxidant activity exerted by C.borivilianum root extracts (i.e., aqueous and ethanolic), to clarify the pharmacological antagonism of chemicals/metals-mediated oxidation. Graded-dose (25 to 1000 µg/ml) of aqueous extract exhibited higher antioxidant potency as evidenced by powerful nitric oxide, superoxide, hydroxyl, DPPH and ABTS·+ radicals scavenging activity along with reducing capacity (Fe3+/ferricyanide complex and FRAP assays), metal chelating ability, as well as markedly suppressed the lipid peroxidation in mitochondrial fractions as compared to ethanolic extract. Further, aqueous extract significantly decreased (P < 0.05) copper-mediated human serum and kinetics of LDL oxidation, as demonstrated by prolongation of lag phase time with decline of oxidation rate, conjugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substances. In addition, the total polyphenol and flavonoid contents of aqueous extract were higher than that of ethanolic extract, which indicated a positive correlation between antioxidant activity and contents of total phenols. The IC50 values of both extracts were also compared with appropriate antioxidant standards. Overall, aqueous extract of C.borivilianum root has significant powerful antioxidant activity and may favorably affect atherosclerosis risk status by reducing LDL oxidation susceptibility.

Purified c-phycoerythrin: safety studies in rats and protective role against permanganate-mediated fibroblast-DNA damage†

We have evaluated in vitro cytotoxicity of cyanobacterial phycoerythrin (C‐PE) on three human cell lines by cell proliferation and neutral red uptake assays. No toxic effects of C‐PE were observed to any of the cell lines tested. The protective role of purified C‐PE to potassium permanganate‐mediated human fibroblast‐DNA damage was assessed by comet assay at 0 (control), 10 and 20 µg C‐PE ml−1 doses in pre‐, simultaneous and post‐mutagen exposure conditions. Significant DNA damage was detected only in post‐mutagen exposure conditions. Our findings confirmed that the C‐PE is non‐toxic and provides protection against permanganate‐mediated DNA damage. The preliminary acute (2000 mg C‐PE kg−1 body weight, b.w.) and 90 day sub‐chronic (0, 5, 15 and 25 mg C‐PE kg−1 b.w./day) oral toxicity studies of purified C‐PE in male albino rats showed no mortality or treatment‐related major clinical signs, and all the doses of C‐PE were well tolerated. The no observed adverse effect level and no observed effect level were found to be 15 and 5 mg C‐PE kg−1 b.w./day respectively. Copyright

Antioxidant properties of Neu2000 on mitochondrial free radicals and oxidative damage.

Neu2000 [2-hydroxy-5-(2,3,5,6-tetrafluoro-4 trifluoromethylbenzylamino) benzoic acid] is a dual-acting neuroprotective agent that functions both as a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist and a free radical scavenger. In the present study, we investigated the scavenging activity of Neu2000 on various classes of reactive oxygen species and reactive nitrogen species (ROS/RNS) as well as its efficacy for reducing free radicals and oxidative stress/damage induced in spinal cord mitochondrial preparations. Neu2000 exerted scavenging activity against superoxide, nitric oxide, and hydroxyl radicals, and efficiently scavenged peroxynitrite. In the mitochondrial studies, Neu2000 markedly inhibited ROS/RNS and hydrogen peroxide levels following antimycin treatment. In addition, Neu2000 effectively scavenged hydroxyl radicals generated by iron(III)-ascorbate, reduced protein carbonyl formation mediated by hydroxyl radicals and peroxynitrite, and prevented glutathione oxidation caused by tert-butyl hydroperoxide in isolated mitochondria. Interestingly, incubation of isolated mitochondria with Neu2000 followed by centrifugation and removal of the supernatant also resulted in a concentration-dependent decrease in lipid peroxidation. This observation suggests that Neu2000 enters mitochondria to target free radicals or indirectly affects mitochondrial function in a manner that promotes antioxidant activity. The results of the present study demonstrate that Neu2000 possesses potent in vitro antioxidant activity due, most likely, to its active phenoxy group.