Purification and characterisation of a novel antioxidant protein molecule from Phyllanthus niruri

Purification and Identification of Novel Antioxidant Peptides Isolated from Geoffroea decorticans Seeds with Anticoagulant Activity

Geoffroea decorticans is a xerophilous deciduous tree present in most arid forests of southern South America, which is commonly used in traditional medicine. The seeds of this tree have been previously investigated for their singular chemical composition, but their protein content has been poorly investigated. Herein, we report the isolation, purification, and characterization of a set of thermostable peptides derived from Geoffroea decorticans seeds (GdAPs) with strong antioxidant and anticoagulant activities. The most potent antioxidant peptides showed a half maximal inhibitory concentration (IC50) of 35.5 ± 0.3 µg/mL determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH). They also caused a dose-dependent prolongation of the aPTT clotting time with an IC50 value of ~82 µg/mL. Interestingly, MALDI-TOF/MS analysis showed the presence of three major peptides with low molecular weights of 2257.199 Da, 2717.165 Da, and 5422.002 Da. The derived amino-acid sequence of GdAPs revealed their unique structural features, exhibiting homology with various proteins present in the genome of Arachis hypogaea. All in all, our data suggest a direct applicability of GdAPs for pharmaceutical purposes.

Phytochemistry and Pharmacology of Phyllanthus niruri L.: A Review

Phyllanthus niruri, a typical member of family Euphorbiaceae, is a small annual herb found throughout the tropical and subtropical regions of both hemispheres. The genus Phyllanthus has been used in traditional medicine for its wide range of pharmacological activities like antimicrobial, antioxidant, anticancer, antiinflammatory, antiplasmodial, antiviral, diuretic and hepatoprotective. This review summarizes the information about morphological, biochemical, ethanobotanical, pharmacological, biological and toxicological activities with special emphasis on mechanism of anticancer activity of P. niruri. Gaps in previous studies such as taxonomic inconsistency of P. niruri, novel phytochemicals and their therapeutic properties, especially mechanisms of anticancerous activity and market products available, have been looked into and addressed. Scientific information related to 83 phytochemicals (including many novel compounds detected recently by the authors) has been provided in a very comprehensive manner. Copyright © 2017 John Wiley & Sons, Ltd.

A 35 kDa Phyllanthus niruri protein suppresses indomethacin mediated hepatic impairments: Its role in Hsp70, HO-1, JNKs and Ca2+ dependent inflammatory pathways

The present study has been conducted to explore a novel strategy to modulate the unfavourable effects of indomethacin by Phyllanthus niruri protein (PNP) and the underlying mechanism PNP exploits for the amelioration of that pathophysiology. In hepatocytes, indomethacin enhanced reactive oxygen species (ROS), reduced intracellular antioxidant capacity, up regulated mitogen activated protein kinase (MAPKs), disrupted mitochondrial membrane potential, activated apoptotic pathways and there by reduced the viability of the hepatocytes. Simultaneous treatment with PNP modulated these detrimental actions of the drug and retained cell viability. Similarly, in mice, indomethacin elevated serum marker enzymes (e.g. Alanine Transaminase), decreased antioxidant enzyme activities, elevated oxidations of lipids and proteins, increased intracellular calcium overload mediated endoplasmic reticular stress (ER stress) pathways, up regulated the pro-inflammatory cytokines and there by leading to the mitochondrial dependent caspase-3 activation and poly-ADP ribose polymerase (PARP) cleavage. Moreover investigation of these inherent molecular pathways exhibited that these alterations are associated with up regulation of MAPKs, inducible nitric oxide synthase (iNOS), heme oxygenase-1 and down regulation of survival proteins. However, PNP suppressed those apoptotic indices as evidenced from histopathological studies and DNA fragmentation analysis. Combining, results suggest that PNP could possibly provide a protection against indomethacin-induced hepatic pathophysiology.

Purification and Characterization of an Antioxidant Protein from Fertilized Eggs

Free radicals may attack cells or tissue, leading to chronic diseases, and antioxidant consumption is potentially useful for removing free radicals. Egg proteins may be used as potential sources of antioxidant considering their ability of scavenging free radicals to apply for food or cosmetics industry. In this study, we obtained a natural antioxidant protein from fertilized eggs, which was a dietary supplement in some Asian countries. Meanwhile, antioxidant activities of these proteins were evaluated using different oxidation systems. With increasing incubation time, the antioxidant activity of these proteins increased during 15 d of incubation. The samples on day 15 were performed for isolation of antioxidant protein. The protein, named P4-1 (MW, 45 kDa), was isolated and purified by consecutive chromatographic methods. P4-1 contained 17 amino acids, which was determined by liquid chromatography-mass spectrometry and Amino Acid Analyzer. Moreover, the amino acid sequence was highly similar to that of ovalbumin. Differential scanning calorimetry showed that the denaturation temperature of P4-1 was 57.16℃. Furthermore, P4-1 suggested high oxygen radical-absorbance activity in ·OH assays, and its antioxidant activity was stable at 30-50℃ in acidic and neutral pH. Thus, these results revealed that P4-1 may be a potential resource as a natural antioxidant.

The pharmacological potential of Phyllanthus niruri

INTRODUCTION

Phyllanthus niruri is a traditional shrub of the genus Phyllanthaceae with long-standing Ayurvedic, Chinese and Malay ethnomedical records. Preliminary studies from cell and animal model have provided valuable scientific evidence for its use.

AIM

This review aims to summarize selected scientific evidence on the pharmacological properties of P. niruri over the past 35 years while identifying potential areas of further development of this herb as an economical adjunct.

METHODS

The review covers literature pertaining to the evidence base therapeutic potential of P. niruri spanning from 1980 to 2015 available on PubMed.

RESULTS

Evidence suggests that the extracts of P. niruri possess hepatoprotective, antiviral, antibacterial, hypolipidaemic, hypoglycaemic, analgesic, anti-inflammatory, cardioprotective, anti-urolithiatic and antihyperuricaemic properties due its novel bioactive compounds.

CONCLUSION

Scientific evidence suggests that there is strong pharmacological potential in developing P. niruri as a drug to be used in liver disorders and in antiviral therapy. Despites this, large-scale heterogeneity in study protocol and unstandardized reporting standards limit the ability for valuable comparison and may mask the ability to replicate these studies. Thus interpretation of findings should be performed with caution and further studies should be performed in line with best practices. More cheminformatics, toxicological and mechanistic studies would aid the progress to clinical trial studies.

Mangiferin attenuates diabetic nephropathy by inhibiting oxidative stress mediated signaling cascade, TNFα related and mitochondrial dependent apoptotic pathways in streptozotocin-induced diabetic rats

Oxidative stress plays a crucial role in the progression of diabetic nephropathy in hyperglycemic conditions. It has already been reported that mangiferin, a natural C-glucosyl xanthone and polyhydroxy polyphenol compound protects kidneys from diabetic nephropathy. However, little is known about the mechanism of its beneficial action in this pathophysiology. The present study, therefore, examines the detailed mechanism of the beneficial action of mangiferin on STZ-induced diabetic nephropathy in Wister rats as the working model. A significant increase in plasma glucose level, kidney to body weight ratio, glomerular hypertrophy and hydropic changes as well as enhanced nephrotoxicity related markers (BUN, plasma creatinine, uric acid and urinary albumin) were observed in the experimental animals. Furthermore, increased oxidative stress related parameters, increased ROS production and decreased the intracellular antioxidant defenses were detected in the kidney. Studies on the oxidative stress mediated signaling cascades in diabetic nephropathy demonstrated that PKC isoforms (PKCα, PKCβ and PKCε), MAPKs (p38, JNK and ERK1/2), transcription factor (NF-κB) and TGF-β1 pathways were involved in this pathophysiology. Besides, TNFα was released in this hyperglycemic condition, which in turn activated caspase 8, cleaved Bid to tBid and finally the mitochorndia-dependent apoptotic pathway. In addition, oxidative stress also disturbed the proapoptotic-antiapoptotic (Bax and Bcl-2) balance and activated mitochorndia-dependent apoptosis via caspase 9, caspase 3 and PARP cleavage. Mangiferin treatment, post to hyperglycemia, successfully inhibited all of these changes and protected the cells from apoptotic death.

Amelioration of aspirin induced oxidative impairment and apoptotic cell death by a novel antioxidant protein molecule isolated from the herb Phyllanthus niruri

Aspirin has been used for a long time as an analgesic and anti-pyretic drug. Limitations of its use, however, remain for the gastro-intestinal side effects and erosions. Although the role of aspirin on gastro-intestinal injury has been extensively studied, the molecular mechanisms underlying aspirin-induced liver and spleen pathophysiology are poorly defined. The present study has been conducted to investigate whether phyllanthus niruri protein (PNP) possesses any protective role against aspirin mediated liver and spleen tissue toxicity, and if so, what signaling pathways it utilizes to convey its protective action. Aspirin administration in mice enhanced serum marker (ALP) levels, reactive oxygen species (ROS) generation, reduced antioxidant power and altered oxidative stress related biochemical parameters in liver and spleen tissues. Moreover, we observed that aspirin intoxication activated both the extrinsic and intrinsic apoptotic pathways, as well as down regulated NF-κB activation and the phosphorylation of p38 and JNK MAPKs. Histological assessments and TUNEL assay also supported that aspirin induced tissue damages are apoptotic in nature. PNP treatment after aspirin exposure effectively neutralizes all these abnormalities via the activation of survival PI3k/Akt pathways. Combining all results suggest that PNP could be a potential protective agent to protect liver and spleen from the detrimental effects of aspirin.

Purification and characterisation of a phosphatidylcholine-binding protein from duck Biceps femoris muscle

The interaction between protein and phospholipids is a widespread phenomenon involving several physiological events in postmortem muscle. We hereby report a method for one-step purification of a phosphatidylcholine-binding (PC-binding) protein from duck Biceps femoris muscle with relatively high purity and yield using ion-exchange chromatography. This PC-binding protein has an inhibitory effect on the activity of phospholipase A2 (PLA2). A decrease (~62.3%) in PLA2 activity was observed. It had a strong affinity to bind PC at pH range of 6.2–6.8 with a peak at pH 6.6 (13.36 ± 0.48 g PC/g protein); in addition, raising ATP content from 1 to 5 μmol/mL enhanced the binding capacity. The PC-binding protein plays a potential role in the integrity of membrane and meat quality.

An update on oxidative stress-mediated organ pathophysiology

Exposure to environmental pollutants and drugs can result in pathophysiological situations in the body. Research in this area is essential as the knowledge on cellular survival and death would help in designing effective therapeutic strategies that are needed for the maintenance of the normal physiological functions of the body. In this regard, naturally occurring bio-molecules can be considered as potential therapeutic targets as they are normally available in commonly consumed foodstuffs and are thought to have minimum side effects. This review article describes the detailed mechanisms of oxidative stress-mediated organ pathophysiology and the ultimate fate of the cells either to survive or to undergo necrotic or apoptotic death. The mechanisms underlying the beneficial role of a number of naturally occurring bioactive molecules in oxidative stress-mediated organ pathophysiology have also been included in the review. The review provides useful information about the recent progress in understanding the mechanism(s) of various types of organ pathophysiology, the complex cross-talk between these pathways, as well as their modulation in stressed conditions. Additionally, it suggests possible therapeutic applications of a number of naturally occurring bioactive molecules in conditions involving oxidative stress.

Cadmium induced pathophysiology: prophylactic role of edible jute (Corchorus olitorius) leaves with special emphasis on oxidative stress and mitochondrial involvement

The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against CdCl₂ intoxication. In vitro bioassay on isolated mice hepatocytes confirmed dose dependent cytoprotective effect of AECO. The CdCl₂ (30 μM) exhibited a significantly increased levels of lipid peroxidation, protein carbonylation along with the reduction of antioxidant enzymes and reduced glutathione levels in hepatocytes. AECO (200 and 400 μg/ml) + CdCl₂ (30 μM) could significantly restore the aforementioned oxidation parameters in hepatocytes. Beside this, AECO could significantly reduce Cd-induced increase in Bad/Bcl-2 ratio and the over-expression of NF-κB, caspase 3 and caspase 9. In in vivo assay, CdCl₂ (4 mg/kg body weight, for 6 days) treated rats exhibited a significantly increased intracellular Cd accumulation, oxidative stress and DNA fragmentation in the organs. In addition, the haematological parameters were significantly altered in the CdCl₂ treated rats. Simultaneous administration of AECO (50 and 100 mg/kg body weight), could significantly restore the biochemical, antioxidant and haematological parameters near to the normal status. Histological studies of the organs supported the protective role of jute leaves. Presence of substantial quantity of phenolic compounds and flavonoids in extract may be responsible for overall protective effect.

Mechanism of the protective action of taurine in toxin and drug induced organ pathophysiology and diabetic complications: a review

Taurine (2-aminoethanesulfonic acid), a conditionally essential amino acid, is found in large concentrations in all mammalian tissues and is particularly abundant in aquatic foods. Taurine exhibits membrane stabilizing, osmoregulatory and cytoprotective effects, antioxidative properties, regulates intracellular Ca(2+) concentration, modulates ion movement and neurotransmitters, reduce the levels of pro-inflammatory cytokines in various organs and controls blood pressure. Recently, emerging evidence from the literature shows the effectiveness of taurine as a protective agent against several environmental toxins and drug-induced multiple organ injuries as the outcome of hepatotoxicity, nephrotoxicity, neurotoxicity, testicular toxicity and cardiotoxicity in several animal models. Besides, taurine is also effective in combating diabetes and its associated complications, including cardiomyopathy, nephropathy, neuropathy, retinopathy and atherosclerosis. These beneficial effects appear to be due to the multiple actions of taurine on cellular functions. This review summarizes the mechanism of the prophylactic role of taurine against several environmental toxins and drug-induced organ pathophysiology and diabetes.

Anti-hyperalgesic activity of corilagin, a tannin isolated from Phyllanthus niruri L. (Euphorbiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Corilagin (β-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-D-glucose) is a tannin isolated from Phyllanthus niruri (Euphorbiaceae). This plant is well known for their therapeutic purposes to treat several diseases associated with dolorous process and are used in several ethno-medicines in tropical and subtropical countries.

AIM OF THE STUDY

This study was designed to evaluate the anti-hyperalgesic activity of corilagin using chemically and thermally based nociception models in mice.

MATERIALS AND METHODS

Corilagin was isolated from Phyllanthus niruri (Euphorbiaceae) by extraction and chromatographic procedures and the anti-hyperalgesic activity was evaluated by using writhing, formalin, capsaicin, glutamate and hot plate tests in mice.

RESULTS

Corilagin presented activity in acetic acid model with the ID50 calculated value of 6.46 (3.09-13.51) being about 20.6 fold more potent than acetylsalicylic acid. It also exhibited activity against the first phase of formalin test with ID50 value of 18.38 (15.15-22.59) μmol/kg. In the capsaicin and glutamate models, corilagin demonstrated significant activity at the 3 mg/kg.

CONCLUSION

The experimental data demonstrated that corilagin exhibits anti-hyperalgesic activity that may be due to interaction with the glutamatergic system.

Mangiferin, a natural xanthone, protects murine liver in Pb(II) induced hepatic damage and cell death via MAP kinase, NF-κB and mitochondria dependent pathways

One of the most well-known naturally occurring environmental heavy metals, lead (Pb) has been reported to cause liver injury and cellular apoptosis by disturbing the prooxidant-antioxidant balance via oxidative stress. Several studies, on the other hand, reported that mangiferin, a naturally occurring xanthone, has been used for a broad range of therapeutic purposes. In the present study, we, therefore, investigated the molecular mechanisms of the protective action of mangiferin against lead-induced hepatic pathophysiology. Lead [Pb(II)] in the form of Pb(NO₃)₂ (at a dose of 5 mg/kg body weight, 6 days, orally) induced oxidative stress, hepatic dysfunction and cell death in murine liver. Post treatment of mangiferin at a dose of 100 mg/kg body weight (6 days, orally), on the other hand, diminished the formation of reactive oxygen species (ROS) and reduced the levels of serum marker enzymes [alanine aminotranferase (ALT) and alkaline phosphatase (ALP)]. Mangiferin also reduced Pb(II) induced alterations in antioxidant machineries, restored the mitochondrial membrane potential as well as mutual regulation of Bcl-2/Bax. Furthermore, mangiferin inhibited Pb(II)-induced activation of mitogen-activated protein kinases (MAPKs) (phospho-ERK 1/2, phosphor-JNK phospho- p38), nuclear translocation of NF-κB and apoptotic cell death as was evidenced by DNA fragmentation, FACS analysis and histological assessment. In vitro studies using hepatocytes as the working model also showed the protective effect of mangiferin in Pb(II) induced cytotoxicity. All these beneficial effects of mangiferin contributes to the considerable reduction of apoptotic hepatic cell death induced by Pb(II). Overall results demonstrate that mangiferin exhibit both antioxidative and antiapoptotic properties and protects the organ in Pb(II) induced hepatic dysfunction.

A 35 kD Phyllanthus niruri protein modulates iron mediated oxidative impairment to hepatocytes via the inhibition of ERKs, p38 MAPKs and activation of PI3k/Akt pathway

It has been reported that the herb, Phyllanthus niruri, possess antioxidant, anti-infection, anti-asthmatic, anti-diuretic, anti-soresis and many more beneficial activities. The goal of our present study was to evaluate the protective role of a 35 kD protein (PNP) isolated from this herb against iron-induced cytotoxicity in murine hepatocytes. Exposure of hepatocytes to iron (FeSO4) caused elevation of reactive oxygen species (ROS) production, enhanced lipid peroxidation and protein carbonylation, depleted glutathione levels, decreased the antioxidant power (FRAP) of the cells and reduced cell viability. Iron mediated cytotoxicity disrupted mitochondrial membrane potential (Δψm) and thereby caused apoptosis mainly by the intrinsic pathway via the down-regulation of IκBα with a concomitant up-regulation of NF-kB as well as the phosphorylation of ERKs and p38 MAP kinases. In addition, iron-induced cytotoxicity disrupted the normal balance of Bcl-2 family proteins in hepatocytes. Incubation of hepatocytes with PNP, however, protected the cells from apoptosis by stabilizing the mitochondria and arresting the release of cytochrome c. It also suppressed caspase activation and cleavage of PARP. Moreover, this protein has strong free radical scavenging activity and thereby scavenged ROS extensively. Combining all, results suggest that simultaneous treatment with PNP might suppress the iron-induced cytotoxicity in hepatocytes.

Purification and characterization of a novel ~18 kDa antioxidant protein from Ginkgo biloba seeds

Ginkgo biloba seeds are widely used as a food and traditional medicine in China. In the present study, a novel antioxidant protein named GBSP was purified from Ginkgo biloba seeds. The protein (GBSP) was purified by homogenization of Ginkgo biloba seed powder in saline solution, 70% ammonium sulphate precipitation, filtration on a DEAE-Cellulose52 anion exchange column, gel filtration on a Sephadex G-50 column, and preparative chromatography on a C₁₈ column using RP-HPLC. GBSP showed an apparent molecular weight of 18 kDa by SDS-PAGE and MALDI-TOF/MS analyses. The amino acid sequence obtained by MALDI-TOF/TOF MS analysis showed GBSP was a novel protein, as no matching protein in was found the database. The protein exhibited significant antioxidant activities against free radicals such as DPPH, ABTS and superoxide anion and showed higher activity than α-tocopherol in a linoleic acid emulsion assay system. Furthermore, GBSP exhibited notable reducing power and a strong chelating effect on Cu²⁺ and Fe²⁺. Therefore, the present study demonstrates, for the first time, that this novel protein from Ginkgo biloba seeds is an excellent antioxidant.

Iron induces hepatocytes death via MAPK activation and mitochondria-dependent apoptotic pathway: beneficial role of glycine

In the present study we investigated the beneficial role of glycine in iron (FeSO₄) induced oxidative damage in murine hepatocytes. Exposure of hepatocytes to 20 μM FeSO₄ for 3 hours enhanced reactive oxygen species (ROS) generation and induced alteration in biochemical parameters related to hepatic oxidative stress. Investigating cell signalling pathway, we observed that iron (FeSO₄) intoxication caused NF-κB activation as well as the phosphorylation of p38 and ERK MAPKs. Iron (FeSO₄) administration also disrupted Bcl-2/Bad protein balance, reduced mitochondrial membrane potential, released cytochrome c and induced the activation of caspases and cleavage of PARP protein. Flow cytometric analysis also confirmed that iron (FeSO₄) induced hepatocytes death is apoptotic in nature. Glycine (10 mM) supplementation, on the other hand, reduced all the iron (FeSO₄) induced apoptotic indices. Combining, results suggest that glycine could be a beneficial agent against iron mediated toxicity in hepatocytes.

Tertiary butyl hydroperoxide induced oxidative damage in mice erythrocytes: Protection by taurine

The present study was undertaken to investigate the protective role of taurine, against t-butyl hydroperoxide (TBHP) induced oxidative stress in murine erythrocytes. Erythrocytes were treated either with TBHP alone or with taurine, followed by TBHP exposure. TBHP-induced oxidative stress increased methemoglobin formation, lipid peroxidation and protein carbonylation in erythrocytes. The same exposure, however, depleted cellular GSH content and altered the activities of the antioxidant enzymes as well as of methemoglobin reductase; reduced activities of Ca(+) and Na(+)/K(+) ATPase and intracellular ATP levels. Taurine transport inhibitor, β-alanine, treated erythrocytes showed increased phosphatidylserine externalization and ROS formation on TBHP exposure and taurine could not revert the effect. TBHP exposure increased intracellular calcium and upregulated the level of calpain. Administration of taurine could, however, prevent the TBHP induced oxidative imbalance. Electron micrographs of erythrocytes showed changed morphology with an increase in the number of echinocytes. Taurine treatment could restore the normal levels of the antioxidant enzymes and metabolites of the erythrocytes. Results suggest that the oxidative insult introduced in erythrocytes by TBHP administration is prevented by taurine mainly via membrane stabilization.

Traditional extract of Pithecellobium dulce fruits protects mice against CCl(4) induced renal oxidative impairments and necrotic cell death

The present study has been carried out to investigate the role of the aqueous extract of the fruits of Pithecellobium dulce (AEPD) against carbon tetrachloride (CCl(4)) induced renal oxidative injury in mice. HPLC analysis shows that AEPD contains phenolics, flavonoids and saponins as the major active components. Creatinine and blood urea nitrogen (BUN) levels were assayed to determine renal protective action of AEPD in CCl(4)-induced renal pathophysiology. Its antioxidant activity was determined by measuring radical scavenging activity, antioxidant enzymes activities, GSH content, protein carbonylation and lipid peroxidation. In addition, FACS analysis, DNA fragmentation and histological studies were carried out to determine its effect in CCl(4) induced renal oxidative injury and cell death. CCl(4) exposure increased the intracellular reactive oxygen species production, decreased intracellular antioxidant defence, reduced mitochondrial membrane potential, attenuated the intracellular ATP content and caused renal cell death mainly via the necrotic pathway as revealed by DNA fragmentation analysis. Treatment with AEPD both prior and post to the toxin exposure protected the organ from CCl(4) induced oxidative insult. Histological studies also support our results. Combining, results suggest that the protective role of AEPD against CCl(4) induced renal oxidative impairments is probably due to the antioxidative properties present in its active constituents.

Cajanus indicus leaf protein: Beneficial role in experimental organ pathophysiology. A review

The herb, Cajanus indicus L, has been and is popular for its medicinal value in India and other countries for long. The herb is mainly cultivated for the seeds which are used as pulses and are rich in proteins. People of rural India and some neighboring countries use the aqueous extract of the leaves of the herb against poor liver function and recently it has been found that the extract is not only useful against liver damage but also beneficial for renal failure and a number of other pathophysiological conditions. Intraperitoneal administration of the aqueous protein fraction of the leaves has shown hepatoprotective activity in mice. The protein fraction revealed the presence of a 43kDa protein having antioxidant and other protective properties in organ pathophysiology. The purified protein, CI-protein, scavenges free radicals generated by different free radical inducers and helps providing cytoprotection. Amino acid sequence of CI-protein has some structural similarity with plastocyanin, an electron carrier protein in photosynthesis. The protein has also been found to be active against a number of organ dysfunction inducer chemicals and drugs, like carbon tetrachloride, thioacetamide and acetaminophen. Signal transduction studies suggest that CI-protein exerts its protective action by free radical scavenging and antioxidative properties; it activates NF-κB and Akt without any involvement of ERK1/ERK2 and STAT-3 in acetaminophen induced hepatic pathophysiology. Besides, it reduces both drug and toxin induced cytotoxicity by decreasing the formation and/or scavenging of free radicals involving cytochrome P450, taking part in detoxification of xenobiotics.

Involvement of both intrinsic and extrinsic pathways in hepatoprotection of arjunolic acid against cadmium induced acute damage in vitro

Cadmium (Cd) is one of the ubiquitous environmental pollutants and is responsible for various organ pathophysiology including hepatic disorders. It is extremely toxic even in low concentrations and bioaccumulate in organisms. The present study has been carried out to investigate the cytoprotective role of arjunolic acid (AA), a tri terpenoid saponin, against Cd induced oxidative impairment and cell death in murine hepatocytes. Administration of cadmium (30 μM), in the form of chloride (CdCl(2)) for 2h, significantly enhanced the ALT, ALP and LDH leakage, increased reactive oxygen species (ROS) production, reduced hepatocytes viability and altered the antioxidant status of hepatocytes by reducing intracellular GSH level, anti-oxidant enzymes activity and increasing intracellular GSSG and lipid peroxidation. Evidence for Cd-induced nature of cell death was sought by flow cytometric analysis. Signal transduction studies revealed that Cd markedly increased the levels of caspase-9, -8, -3, Fas and Bid, decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol, disturbed the Bcl-2 family protein balance, cleaved PARP protein and ultimately led to apoptotic cell death. Results showed that Cd could trigger both intrinsic and extrinsic apoptotic pathways. In addition, Cd markedly increased NF-κB nuclear translocation in association with IKKα/β phosphorylation and IκBα degradation. Simultaneous treatment with AA (200 μM), however, reduced Cd-induced oxidative stress, attenuated the nuclear translocation of NF-κB and protects the hepatocytes from Cd-induced apoptotic death. Combining, data suggest that Cd-induced hepatic dysfunction and apoptosis might be supported by the ROS formation and mediated via the activation of NF-κB. AA treatment, on the other hand, reduced Cd-induced oxidative stress, attenuated the activation of NF-κB and mitochondrion-dependent and independent apoptotic signaling pathways.

Protective role of a coumarin-derived schiff base scaffold against tertiary butyl hydroperoxide (TBHP)-induced oxidative impairment and cell death via MAPKs, NF-κB and mitochondria-dependent pathways

The present study investigated the antioxidant signalling mechanism of a coumarin-derived schiff base (CSB) scaffold against tert-butylhydroperoxide (TBHP) induced oxidative insult in murine hepatocytes. CSB possesses DPPH and other free radical scavenging activities. TBHP reduced cell viability and intracellular antioxidant status accompanied by an increase in intracellular ROS production in hepatocytes. TBHP also activated phospho-ERK1/2, phospho-p38 and NF-κB, altered the Bcl-2/Bad ratio, reduced mitochondrial membrane potential, released cytochrome C and activated caspase 3, suggesting that TBHP induced oxidative stress responsive cell death via apoptotic pathway. FACS analysis and DNA fragmentation studies also confirmed the apoptotic cell death in TBHP exposed hepatocytes. Treatment with CSB effectively reduced these adverse effects by preventing the oxidative insult, alteration in the redox-sensitive signalling cascades and mitochondrial events. Combining, results suggest that antioxidant property of CSB make the molecule to be a potential protective measure against oxidative insult, cytotoxicity and cell death.

Modulation of mercury-induced mitochondria-dependent apoptosis by glycine in hepatocytes

Mercury (Hg) is one of the universal environmental pollutants and is responsible for various organ pathophysiology including oxidative stress-induced hepatic disorders. In the present study, we aimed to explore the protective role of glycine in Hg-induced cytotoxicity and cell death in murine hepatocytes. Exposure of mercury (20 μM), in the form HgCl2 for 1 h, significantly enhanced the ALT and ALP leakage, increased reactive oxygen species production, reduced cell viability and distorted the antioxidant status of hepatocytes. Flow cytometric analyses shows that Hg-induced apoptotic death in hepatocytes. Mechanism of this pathophysiology involves reduced mitochondrial membrane potential, variations in Bcl-2/Bad proteins, activation of caspases and cleavage of PARP protein. In addition, Hg distinctly increased NF-κB phosphorylation in association with IKKα phosphorylation and IκBα degradation. Concurrent treatment with glycine (45 mM), however, reduced Hg-induced oxidative stress, attenuated the changes in NF-κB phosphorylation and protects hepatocytes from Hg-induced apoptotic death. Hg also distinctly increased the phosphorylation of p38, JNK and ERK mitogen-activated protein kinase (MAPKs). Glycine treatment suppressed these apoptotic events, signifying its protective role in Hg-induced hepatocyte apoptosis as referred by reduction of p38, JNK and ERK MAPK signaling pathways. Results suggest that glycine can modulate Hg-induced oxidative stress and apoptosis in hepatocytes probably because of its antioxidant activity and functioning via mitochondria-dependent pathways and could be a beneficial agent in oxidative stress-mediated liver diseases.