Natural antioxidants: therapeutic prospects for cancer and neurological diseases

Impacts of Curcumin Treatment on Experimental Sepsis: A Systematic Review

Background and Aims

Sepsis is defined as a life-threatening organ dysfunction due to a dysregulated host immune response to an infection. Curcumin is a yellow polyphenol derived from the rhizome of Curcuma longa with anti-inflammatory and antioxidant properties scientifically proven, a condition that allowed its use as a tool in the treatment of sepsis. Thus, the purpose of this article was to systematically review the evidence on the impact of curcumin's anti-inflammatory effect on experimental sepsis.

Methods

For this, the PubMed, MEDLINE, EMBASE, Scopus, Web of Science, and LILACS databases were used, and the research was not limited to a specific publication period. Only original articles in English using in vivo experimental models (rats or mice) of sepsis induction performed by administration of lipopolysaccharide (LPS) or cecal ligation and perforation surgery (CLP) were included in the study. Studies using curcumin in dry extract or with a high degree of purity were included. At initial screening, 546 articles were selected, and of these, 223 were eligible for primary evaluation. Finally, 12 articles with full text met all inclusion criteria. Our results showed that curcumin may inhibit sepsis-induced complications such as brain, heart, liver, lungs, and kidney damage. Curcumin can inhibit inflammatory factors, prevent oxidative stress, and regulate immune responses in sepsis. Additionally, curcumin increased significantly the survival rates after experimental sepsis in several studies. The modulation of the immune response and mortality by curcumin reinforces its protective effect on sepsis and indicates a potential therapeutic tool for the treatment of sepsis.

Antioxidant, cytotoxic and apoptotic activities of the rhizome of Zingiber zerumbet Linn. in Ehrlich ascites carcinoma bearing Swiss albino mice

Due to having a long history of traditional uses as a functional food, Zingiber zerumbet was selected here to explore the inherent antioxidant and antineoplastic activities of methanolic extract of its rhizome (MEZZR) against Ehrlich ascites carcinoma (EAC) cells. The rich polyphenol containing MEZZR showed a marked DPPH, ABTS, nitric oxide radicals and lipid peroxidation inhibition activity with an IC₅₀ of 3.43 ± 1.25, 11.38 ± 1.39, 23.12 ± 3.39 and 16.47 ± 1.47 µg/ml, respectively, when compared to the standard catechin. In vivo, MEZZR significantly inhibited EAC cell growth, decreased body weight gain, increased life span and restored the altered hematological characteristics of EAC-bearing mice. Moreover, MEZZR induced nuclear condensation and fragmentation, which are notable features of apoptosis as observed by fluorescence microscopy after staining EAC cells of MEZZR-treated mice with Hoechst 33342. Additionally, in vitro, the cell growth inhibition caused by the MEZZR in MTT assay, was remarkably decreased in the presence of caspase-3, -8 and -9 inhibitors. This study thus suggests that MEZZR may possess promising antiproliferative efficacy against EAC cells by inducing cell apoptosis.

Preparation, Antioxidant Properties and Ability to Increase Intracellular NO of a New Pyridoxine Derivative B6NO

In the case of various pathologies, an imbalance between ROS generation and the endogenous AOS can be observed, which leads to excessive ROS accumulation, intensification of LPO processes, and oxidative stress. For the prevention of diseases associated with oxidative stress, drugs with antioxidant activity can be used. The cytotoxic, antioxidant, and NO-donor properties of the new hybrid compound B6NO (di(3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridinium) salt of 2-(nitrooxy)butanedioic acid) were studied. It was determined that B6NO chelates iron ions by 94%, which indicates B6NO's ability to block the Fenton reaction. The hybrid compound B6NO inhibits the process of initiated lipid peroxidation more effectively than pyridoxine. It was shown that B6NO exhibits antioxidant properties by decreasing ROS concentration in normal cells during the oxidative stress induction by tert-Butyl peroxide. At the same time, the B6NO antioxidant activity on tumor cells was significantly lower. B6NO significantly increases the intracellular nitrogen monoxide accumulation and showed low cytotoxicity for normal cells (IC50 > 4 mM). Thus, the results indicate a high potential of the B6NO as an antioxidant compound.

Coffea arabica Bean Extracts and Vitamin C: A Novel Combination Unleashes MCF-7 Cell Death

BACKGROUND

Vitamin C (VC) is believed to enhance immunity and is regularly integrated as a supplementary agent during several treatments.

OBJECTIVE

The green (GC) and roasted (RC) coffee (Coffea arabica) aqueous extracts (0, 125, 250 and 500 μg/ml) combined with VC (50 μg/ml) were examined on the cancerous MCF-7 cell line and normal human lymphocytes.

METHODS

Neutral red uptake assay, comet assay, immunocytochemical reactivity for protein expression and mRNA expression of apoptosis-related genes were performed.

RESULTS

A significant (P< 0.05) concentration-dependent increase of apoptotic features, such as morphological changes, and abundant nuclear condensation, altered the expression of p53 and caspase-3 mRNA, down-regulation of Bcl-2 protein as well as the acidic autophagosomal vacuolization in treated cells. The oxidative stress and DNA single-strand breaks were noticed too.

CONCLUSION

These results suggest that coffee in combination with VC undergoes apoptotic anticancer pathway. This supports the integration of coffee and VC as a valuable candidate for anticancer research and treatments.

High incidence of brain and other nervous system cancer identified in two mining counties, 2001-2015

Two counties in Montana, Deer Lodge and Silver Bow (DL/SB), have two Superfund sites, as well as an active copper and molybdenum mine in SB. The population living in proximity to these sites are exposed to additional metals and some have been shown to be neurotoxic, especially for children; thus, this study focused on the incidence of brain and other nervous system cancers. The Montana Central Tumor Registry data was used to identify the cases in DL/SB and the remaining 54 counties of Montana (comparison group). After controlling for sex, cancer stage, and year of diagnosis, we found an incidence rate ratio for DL/SB versus comparison group of 6.28 (95% CI: 2.32-17.02) for children ages birth to 4 years, and 3.95 (95% CI: 1.66-9.38) for adults age 30-34 years. The high incidence rate of the brain cancer in the two age groups requires public health action.

Understanding the role of key amino acids in regulation of proline dehydrogenase/proline oxidase (prodh/pox)-dependent apoptosis/autophagy as an approach to targeted cancer therapy

In stress conditions, as neoplastic transformation, amino acids serve not only as nutrients to maintain the cell survival but also as mediators of several regulatory pathways which are involved in apoptosis and autophagy. Especially, under glucose deprivation, in order to maintain the cell survival, proline and glutamine together with other glutamine-derived products such as glutamate, alpha-ketoglutarate, and ornithine serve as alternative sources of energy. They are substrates for production of pyrroline-5-carboxylate which is the product of conversion of proline by proline dehydrogenase/ proline oxidase (PRODH/POX) to produce ATP for protective autophagy or reactive oxygen species for apoptosis. Interconversion of proline, ornithine, and glutamate may therefore regulate PRODH/POX-dependent apoptosis/autophagy. The key amino acid is proline, circulating between mitochondria and cytoplasm in the proline cycle. This shuttle is known as proline cycle. It is coupled to pentose phosphate pathway producing nucleotides for DNA biosynthesis. PRODH/POX is also linked to p53 and AMP-activated protein kinase (AMPK)-dependent pathways. Proline availability for PRODH/POX-dependent apoptosis/autophagy is regulated at the level of collagen biosynthesis (proline utilizing process) and prolidase activity (proline supporting process). In this review, we suggest that amino acid metabolism linking TCA and Urea cycles affect PRODH/POX-dependent apoptosis/autophagy and the knowledge might be useful to targeted cancer therapy.

Evaluation of epithelial transport and oxidative stress protection of nanoengineered curcumin derivative-cyclodextrin formulation for ocular delivery

Ocular drug delivery has been a well-known route for the drug administration for the treatment of ocular diseases. However, numerous anatomical and physiological barriers prevailing in the eye itself create considerable challenges for achieving the necessitated therapeutic efficacy along with ocular bioavailability. However, recent advances in nanoengineered strategies hold definite promises in terms of devising improved ophthalmic medicines for the effective drug delivery to target the sites with enhanced ocular bioavailability. Curcumin, a hydrophobic polyphenol yellow colored compound, and its metabolic reduced product, tetrahydrocurcumin (THC), have been known for their beneficial pharmacological functions, such as anti-inflammatory or anti-oxidant activities at various tissue sites. However, the low aqueous solubility of these compounds results in their poor bioavailability, thereby limiting their widespread application. Therefore, in the present study, we investigated the changes in drug solubility by forming inclusion complexes with different derivatives of hydroxypropyl (HP)-cyclodextrins (CD). To this end, the spray drying technique was used for nanoengineering curcumin or THC-loaded formulations to improve the stability of formulations during the storage. The formulations were characterized in terms of physicochemical properties and cellular permeability. The results demonstrated that the encapsulation of curcumin (or THC) into the HP-CDs significantly increased the drug solubility and enhanced the corneal and retinal epithelial permeability. Curcumin or THC complexes in HP-CDs with improved bioavailability also induced anti-oxidant activity (SOD1, CAT1, and HMOX1) in higher levels in the ocular epithelial cells and showed oxidative protection effects in rabbit cornea tissues that will boost up their application in ocular medicine.

Anti-Parkinson Potential of Silymarin: Mechanistic Insight and Therapeutic Standing

Parkinson’s disease (PD) involves aggregation of α-synuclein and progressive loss of dopaminergic neurons. Pathogenesis of PD may also be related to one’s genetic background. PD is most common among geriatric population and approximately 1–2% of population suffers over age 65 years. Currently no successful therapies are in practice for the management of PD and available therapies tend to decrease the symptoms of PD only. Furthermore, these are associated with diverse range of adverse effects profile. The neuroprotective effects of polyphenols are widely studied and documented. Among phytochemicals, silymarin is one of the most widely used flavonoids because of its extensive therapeutic properties and has been indicated in pathological conditions of prostate, CNS, lungs, skin, liver, and pancreas. Silymarin is a mixture of flavonolignans (silybin, isosilybin, and silychristin), small amount of flavonoids (taxifolin), fatty acids, and other polyphenolic compounds extracted from the dried fruit of Silybum marianum and is clinically used for hepatoprotective effects since ancient times. Neuroprotective effects of silymarin have been studied in various models of neurological disorders such as Alzheimer’s disease, PD, and cerebral ischemia. The aim of the present study is to provide a comprehensive review of the recent literature exploring the effects of silymarin administration on the progression of PD. Reducing oxidative stress, inflammatory cytokines, altering cellular apoptosis machinery, and estrogen receptor machinery are mechanisms that are responsible for neuroprotection by silymarin, as discussed in this review. Additionally, because of poor aqueous solubility, the bioavailability of silymarin is low and only 23–47% of silymarin reaches systemic circulation after oral administration. Our primary focus is on the chemical basis of the pharmacology of silymarin in the treatment of PD and its mechanisms and possible therapeutic/clinical status while addressing the bioavailability limitation.

Migration Rate Inhibition of Breast Cancer Cells Treated by Caffeic Acid and Caffeic Acid Phenethyl Ester: An In Vitro Comparison Study

One of the deadliest cancers among women is a breast cancer. Research has shown that two natural substances occurring in propolis, caffeic acid (CA) and caffeic acid phenethyl ester (CAPE), have significant anticancer effects. The purpose of our in vitro study was to compare cytotoxic activity and migration rate inhibition using CA and CAPE (doses of 50 and 100 µm) against triple-negative, MDA-MB-231 breast adenocarcinoma line cells, drawn from Caucasian women. Viability was measured by XTT-NR-SRB assay (Tetrazolium hydroxide-Neutral Red-Sulforhodamine B) for 24 h and 48 h periods. Cell migration for wound healing assay was taken for 0 h, 8 h, 16 h, and 24 h periods. CAPE displayed more than two times higher cytotoxicity against MDA-MB-231 cells. IC₅₀ values for the XTT assay were as follows: CA for 24 h and 48 h were 150.94 µM and 108.42 µM, respectively, while CAPE was 68.82 µM for 24 h and 55.79 µM for 48 h. For the NR assay: CA was 135.85 µM at 24 h and 103.23 µM at 48 h, while CAPE was 64.04 µM at 24 h and 53.25 µM at 48 h. For the SRB assay: CA at 24 h was 139.80 µM and at 48 h 103.98 µM, while CAPE was 66.86 µM at 24 h and 47.73 µM at 48 h. Both agents suspended the migration rate; however, CAPE displayed better activity. Notably, for the 100 µM CAPE dose, motility of the tested breast carcinoma cells was halted.

Liver injury following small intestinal ischemia reperfusion in rats is attenuated by Pistacia lentiscus oil: antioxidant and anti-inflammatory effects

CONTEXT

Intestinal ischemia-reperfusion (IIR) not only leads to severe intestine damage but also induced subsequent destruction of remote organs.

OBJECTIVE

We investigated the protective effect of Pistascia lentiscus L. (Anacardiaceae) oil on IIR.

MATERIALS AND METHODS

Wistar rats were divided into three groups: sham, intestinal IR and P. lentiscus pretreatment (n = 18 each). In the pretreatment group, oil was administered 1 h before induction of warm ischemia.

RESULTS

IIR led to severe liver damage manifested as a significant (p < .05) increase of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Pistacia lentiscus oil decreased the visible intestinal damage, as well as a significant decrease in serum AST and ALT levels. In addition, Pistacia lentiscus reduce liver injury, as evidenced by the decrease in liver tissue myeloperoxidase activity and lipoperoxidation (MDA) level.

CONCLUSION

Pistascia lentiscus attenuates liver injury induced by IIR, attributable to the antioxidant and anti-inflammatory effect.

The neurotoxicity of iron, copper and cobalt in Parkinson's disease through ROS-mediated mechanisms

Parkinson's disease (PD) is the second most common neurodegenerative disease with gradual loss of dopaminergic neurons. Despite extensive research in the past decades, the etiology of PD remains elusive. Nevertheless, multiple lines of evidence suggest that oxidative stress is one of the common causes in the pathogenesis of PD. It has also been suggested that heavy metal-associated oxidative stress may be implicated in the etiology and pathogenesis of PD. Here we review the roles of redox metals, including iron, copper and cobalt, in PD. Iron is a highly reactive element and deregulation of iron homeostasis is accompanied by concomitant oxidation processes in PD. Copper is a key metal in cell division process, and it has been shown to have an important role in neurodegenerative diseases such as PD. Cobalt induces the generation of reactive oxygen species (ROS) and DNA damage in brain tissues.

Antioxidants in liver health

Liver diseases are a worldwide medical problem because the liver is the principal detoxifying organ and maintains metabolic homeostasis. The liver metabolizes various compounds that produce free radicals (FR). However, antioxidants scavenge FR and maintain the oxidative/antioxidative balance in the liver. When the liver oxidative/antioxidative balance is disrupted, the state is termed oxidative stress. Oxidative stress leads to deleterious processes in the liver and produces liver diseases. Therefore, restoring antioxidants is essential to maintain homeostasis. One method of restoring antioxidants is to consume natural compounds with antioxidant capacity. The objective of this review is to provide information pertaining to various antioxidants found in food that have demonstrated utility in improving liver diseases.

CAPE Analogs Induce Growth Arrest and Apoptosis in Breast Cancer Cells

Breast cancer is the second leading cause of death amongst women worldwide. As a result, many have turned their attention to new alternative approaches to treat this disease. Caffeic acid phenylethyl ester (CAPE), a well-known active compound from bee propolis, has been previously identified as a strong antioxidant, anti-inflammatory, antiviral and anticancer molecule. In fact, CAPE is well documented as inducing cell death by inhibiting NFκB and by inducing pro-apoptotic pathways (i.e., p53). With the objective of developing stronger anticancer compounds, we studied 18 recently described CAPE derivatives for their ability to induce apoptosis in breast cancer cell lines. Five of the said compounds, including CAPE, were selected and subsequently characterised for their anticancer mechanism of action. We validated that CAPE is a potent inducer of caspase-dependent apoptosis. Interestingly, some newly synthesized CAPE derivatives also showed greater cell death activity than the lead CAPE structure. Similarly to CAPE, analog compounds elicited p53 activation. Interestingly, one compound in particular, analog 10, induced apoptosis in a p53-mutated cell line. These results suggest that our new CAPE analog compounds may display the capacity to induce breast cancer apoptosis in a p53-dependent and/or independent manner. These CAPE analogs could thus provide new therapeutic approaches for patients with varying genotypic signatures (such as p53 mutations) in a more specific and targeted fashion.

Sasa quelpaertensis Leaf Extract Inhibits Colon Cancer by Regulating Cancer Cell Stemness in Vitro and in Vivo

A rare subpopulation of cancer cells, termed cancer stem cells (CSCs), may be responsible for tumor relapse and resistance to conventional chemotherapy. The development of a non-toxic, natural treatment for the elimination of CSCs is considered a strategy for cancer treatment with minimal side effects. In the present study, the potential for Sasa quelpaertensis leaf extract (SQE) and its two bioactive compounds, tricin and p-coumaric acid, to exert anti-CSC effects by suppressing cancer stemness characteristics were evaluated in colon cancer cells. CD133⁺CD44⁺ cells were isolated from HT29 and HCT116 cell lines using flow-activated cell sorting (FACs). SQE treatment was found to significantly suppress the self-renewal capacity of both cell lines. SQE treatment was also associated with the down-regulation of β-catenin and phosphorylated GSK3β, while significantly enhancing cell differentiation by up-regulating CK20 expression and blocking the expression of several stem cell markers, including DLK1, Notch1, and Sox-2. In vivo, SQE supplementation suppressed tumor growth in a xenograft model by down-regulating stem cell markers and β-catenin as well as HIF-1α signaling. Compared with two bioactive compounds of SQE, SQE exhibited the most effective anti-CSC properties. Taken together, these results provide evidence that SQE inhibits colon cancer by regulating the characteristics of CSCs.

Heavy metals and epigenetic alterations in brain tumors

Heavy metals and their derivatives can cause various diseases. Numerous studies have evaluated the possible link between exposure to heavy metals and various cancers. Recent data show a correlation between heavy metals and aberration of genetic and epigenetic patterns. From a literature search we noticed few experimental and epidemiological studies that evaluate a possible correlation between heavy metals and brain tumors. Gliomas arise due to genetic and epigenetic alterations of glial cells. Changes in gene expression result in the alteration of the cellular division process. Epigenetic alterations in brain tumors include the hypermethylation of CpG group, hypomethylation of specific genes, aberrant activation of genes, and changes in the position of various histones. Heavy metals are capable of generating reactive oxygen assumes that key functions in various pathological mechanisms. Alteration of homeostasis of metals could cause the overproduction of reactive oxygen species and induce DNA damage, lipid peroxidation, and alteration of proteins. In this study we summarize the possible correlation between heavy metals, epigenetic alterations and brain tumors. We report, moreover, the review of relevant literature.

Effect of Inhaling Cymbopogon martinii Essential Oil and Geraniol on Serum Biochemistry Parameters and Oxidative Stress in Rats

The effects of the inhalation of Cymbopogon martinii essential oil (EO) and geraniol on Wistar rats were evaluated for biochemical parameters and hepatic oxidative stress. Wistar rats were divided into three groups (n = 8): G1 was control group, treated with saline solution; G2 received geraniol; and G3 received C. martinii EO by inhalation during 30 days. No significant differences were observed in glycemia and triacylglycerol levels; G2 and G3 decreased (P < 0.05) total cholesterol level. There were no differences in serum protein, urea, aspartate aminotransferase activity, and total hepatic protein. Creatinine levels increased in G2 but decreased in G3. Alanine aminotransferase activity and lipid hydroperoxide were higher in G2 than in G3. Catalase and superoxide dismutase activities were higher in G3. C. martinii EO and geraniol increased glutathione peroxidase. Oxidative stress caused by geraniol may have triggered some degree of hepatic toxicity, as verified by the increase in serum creatinine and alanine aminotransferase. Therefore, the beneficial effects of EO on oxidative stress can prevent the toxicity in the liver. This proves possible interactions between geraniol and numerous chemical compounds present in C. martinii EO.

Antioxidant Potential of Plumieride against CCl₄-Induced Peroxidative Damage in Rats

In search of a new potent as an antioxidant from natural sources, plumieride—an iridoid isolated from the methanol extract of the bark of Plumeria bicolor (family Apocynaceae) was evaluated for its antioxidant potential against CCl₄-induced peroxidative damage in liver of rats. The antioxidant potential was evaluated by using hepatic tissue for SOD (superoxide dismutase), CAT (catalase), GSH (reduced glutathione), GPx (glutathione peroxidase), GR (glutathione reductase) and LPO (lipid peroxidation) alongwith the concomitant blood serum for AST & ALT (aspartate and alanine transaminases), GGT (gamma glutamyl transpeptidase), ALP (alkaline phosphatase), total bilirubin and total protein contents. All the biochemical parameters were significantly (p ≤ 0.001) altered by CCl₄ (0.3 mL/kg body weight/twice a week, intra-peritoneally for 30 days). Simultaneously, oral treatment with plumieride (5, 10 and 20 mg/kg body weight/day for 30 days), restored all the parameters towards a normal level, remarkably. The histological findings of liver sections further corroborated the antioxidant potential of plumieride compared with standard drug-silymarin. In conclusion, plumieride consists of sugar molecules, which have alcoholic groups. Therefore, the alcoholic groups of sugar increase its antioxidant potential through intermolecular hydrogen bonding along with the thiol(SH) group of non-protein thiols and enzymes resulting in the restoration of the antioxidant system. Therefore, it might be considered a natural antioxidant against peroxidative damage in rats.

Dietary Lycium barbarum polysaccharide induces Nrf2/ARE pathway and ameliorates insulin resistance induced by high-fat via activation of PI3K/AKT signaling

Lycium barbarum polysaccharide (LBP), an antioxidant from wolfberry, displays the antioxidative and anti-inflammatory effects on experimental models of insulin resistance in vivo. However, the effective mechanism of LBP on high-fat diet-induced insulin resistance is still unknown. The objective of the study was to investigate the mechanism involved in LBP-mediated phosphatidylinositol 3-kinase (PI3K)/AKT/Nrf2 axis against high-fat-induced insulin resistance. HepG2 cells were incubated with LBP for 12 hrs in the presence of palmitate. C57BL/6J mice were fed a high-fat diet supplemented with LBP for 24 weeks. We analyzed the expression of nuclear factor-E2-related factor 2 (Nrf2), Jun N-terminal kinases (JNK), and glycogen synthase kinase 3β (GSK3β) involved in insulin signaling pathway in vivo and in vitro. First, LBP significantly induced phosphorylation of Nrf2 through PI3K/AKT signaling. Second, LBP obviously increased detoxification and antioxidant enzymes expression and reduced reactive oxygen species (ROS) levels via PI3K/AKT/Nrf2 axis. Third, LBP also regulated phosphorylation levels of GSK3β and JNK through PI3K/AKT signaling. Finally, LBP significantly reversed glycolytic and gluconeogenic genes expression via the activation of Nrf2-mediated cytoprotective effects. In summary, LBP is novel antioxidant against insulin resistance induced by high-fat diet via activation of PI3K/AKT/Nrf2 pathway.

Acute liver failure in rats activates glutamine-glutamate cycle but declines antioxidant enzymes to induce oxidative stress in cerebral cortex and cerebellum

Background and Purpose

Liver dysfunction led hyperammonemia (HA) causes a nervous system disorder; hepatic encephalopathy (HE). In the brain, ammonia induced glutamate-excitotoxicity and oxidative stress are considered to play important roles in the pathogenesis of HE. The brain ammonia metabolism and antioxidant enzymes constitute the main components of this mechanism; however, need to be defined in a suitable animal model. This study was aimed to examine this aspect in the rats with acute liver failure (ALF).

Methods

ALF in the rats was induced by intraperitoneal administration of 300 mg thioacetamide/Kg. b.w up to 2 days. Glutamine synthetase (GS) and glutaminase (GA), the two brain ammonia metabolizing enzymes vis a vis ammonia and glutamate levels and profiles of all the antioxidant enzymes vis a vis oxidative stress markers were measured in the cerebral cortex and cerebellum of the control and the ALF rats.

Results

The ALF rats showed significantly increased levels of ammonia in the blood (HA) but little changes in the cortex and cerebellum. This was consistent with the activation of the GS-GA cycle and static levels of glutamate in these brain regions. However, significantly increased levels of lipid peroxidation and protein carbonyl contents were consistent with the reduced levels of all the antioxidant enzymes in both the brain regions of these ALF rats.

Conclusion

ALF activates the GS-GA cycle to metabolize excess ammonia and thereby, maintains static levels of ammonia and glutamate in the cerebral cortex and cerebellum. Moreover, ALF induces oxidative stress by reducing the levels of all the antioxidant enzymes which is likely to play important role, independent of glutamate levels, in the pathogenesis of acute HE.

Oxidative stress--implications, source and its prevention

Oxidative stress has been a major predicament of present day living. It has been the product of imbalance between the processes involved in free radical generation and their neutralization by enzymatic and non-enzymatic defence mechanisms. The oxidative stress has been contributed by numerous factors including heavy metals, organic compound-rich industrial effluents, air pollutants and changing lifestyle pattern focussing mainly on alcohol consumption, dietary habits, sun exposure, nuclear emissions, etc. The most common outcome of oxidative stress is the increased damage of lipid, DNA and proteins that resulted in the development of different pathologies. Among these pathologies, cancer is the most devastating and linked to multiple mutations arising due to oxidative DNA and protein damage that ultimately affect the integrity of the genome. The chemopreventive agents particularly nutraceuticals are found to be effective in reducing cancer incidences as these components have immense antioxidative, antimutagenic and antiproliferative potentials and are an important part of our dietary components. These secondary metabolites, due to their unique chemical structure, facilitate cell-to-cell communication, repair DNA damage by the downregulation of transcription factors and inhibit the activity of protein kinases and cytochrome P450-dependent mixed function oxidases. These phytochemicals, therefore, are most appropriate in combating oxidative stress-related disorders due to their tendency to exert better protective effect without having any distinct side effect.

The functional role of MnSOD as a biomarker of human diseases and therapeutic potential of a new isoform of a human recombinant MnSOD

Reactive oxygen species (ROS) are generated as a consequence of metabolic reactions in the mitochondria of eukaryotic cells. This work describes the role of the manganese superoxide dismutase (MnSOD) as a biomarker of different human diseases and proposes a new therapeutic application for the prevention of cancer and its treatment. The paper also describes how a new form of human MnSOD was discovered, its initial application, and its clinical potentials. The MnSOD isolated from a human liposarcoma cell line (LSA) was able to kill cancer cells expressing estrogen receptors, but it did not have cytotoxic effects on normal cells. Together with its oncotoxic activity, the recombinant MnSOD (rMnSOD) exerts a radioprotective effect on normal cells irradiated with X-rays. The rMnSOD is characterized by the presence of a leader peptide, which allows the protein to enter cells: this unique property can be used in the radiodiagnosis of cancer or chemotherapy, conjugating radioactive substances or chemotherapic drugs to the leader peptide of the MnSOD. Compared to traditional chemotherapic agents, the drugs conjugated with the leader peptide of MnSOD can selectively reach and enter cancer cells, thus reducing the side effects of traditional treatments.

Gracilaria edulis extract induces apoptosis and inhibits tumor in Ehrlich ascites tumor cells in vivo

BACKGROUND

Marine environment is inestimable for their chemical and biological diversity and therefore is an extraordinary resource for the discovery of new anticancer drugs. Recent development in elucidation of the mechanism and therapeutic action of natural products helped to evaluate for their potential activity.

METHODS

We evaluated Gracilaria edulis J. Ag (Brown algae), for its antitumor potential against the Ehrlich ascites tumor (EAT) in vivo and in vitro. Cytotoxicity evaluation of Ethanol Extract of Gracilaria edulis (EEGE) using EAT cells showed significant activity. In vitro studies indicated that EEGE cytotoxicity to EAT cells is mediated through its ability to produce reactive oxygen species (ROS) and therefore decreasing intracellular glutathione (GSH) levels may be attributed to oxidative stress.

RESULTS

Apoptotic parameters including Annexin-V positive cells, increased levels of DNA fragmentation and increased caspase-2, caspase-3 and caspase-9 activities indicated the mechanism might be by inducing apoptosis. Intraperitoneally administration of EEGE to EAT-bearing mice helped to increase the lifespan of the animals significantly inhibited tumor growth and increased survival of mice. Extensive hematology, biochemistry and histopathological analysis of liver and kidney indicated that daily doses of EEGE up to 300 mg/kg for 35 days are well tolerated and did not cause hematotoxicity nor renal or hepatotoxicity.

CONCLUSION

Comprehensive antitumor analysis in animal model and in Ehrlich Ascites Tumor cells was done including biochemical, and pathological evaluations indicate antitumor activity of the extract and non toxic in vivo. It was evident that the mechanism explains the apoptotic activity of the algae extract.

The protective effect of Bcl-xl overexpression against oxidative stress-induced vascular endothelial cell injury and the role of the Akt/eNOS pathway

Restenosis after intraluminal or open vascular reconstruction remains an important clinical problem. Vascular endothelial cell (EC) injury induced by oxidative stress plays an important role in the development of intimal hyperplasia. In this study, we sought to evaluate the protective effects of Bcl-xl overexpression in vitro on oxidative stress-induced EC injury and the role of the Akt/endothelial nitric oxide synthase (eNOS) pathway. Human umbilical vein endothelial cells (HUVECs) exposed to hydrogen peroxide (H₂O₂, 0.5 mM) were used as the experimental oxidative stress model. The Bcl-xl gene was transferred into HUVECs through recombinant adenovirus vector pAdxsi-GFP-Bcl-xl before oxidative treatment. Cell apoptosis was evaluated by Annexin V/propidium iodide and Hoechst staining, caspase-7 and PARP cleavage. Cell viability was assessed using the cell counting kit-8 assay, proliferating cell nuclear antigen (PCNA) immunocytochemical detection and the scratching assay. Expressions of Akt, phospho-Akt and eNOS were detected by Western blotting. Our results showed that H₂O₂ induced apoptosis and decreased the cell viability of HUVECs. Bcl-xl overexpression significantly protected cells from H₂O₂-induced cell damage and apoptosis and maintained the cell function. Furthermore, the level of phospho-Akt and eNOS protein expression was significantly elevated when pretreated with Bcl-xl gene transferring. These findings suggest that Bcl-xl overexpression exerts an anti-apoptotic and protective effect on EC function. The Akt/eNOS signaling pathway is probably involved in these processes.

Protective effect of BAG5 on MPP+-induced apoptosis in PC12 cells

OBJECTIVES

Parkinson's disease (PD) is the most common neurodegenerative disease in humans, and an abundance of evidence has implicated apoptosis signaling pathways in the neurodegeneration of PD. The purpose of this study was to assess the role of B-cell lymphoma 2 (Bcl-2)-associated athanogene 5 (BAG5) protein, which was previously confirmed to play an important role in the pathogenesis of PD, in the regulation of apoptosis induced by 1-methyl-4-phenyl-pyridinium (MPP(+)) in PC12 cells.

METHODS

PC12 cells were treated with MPP(+) for 48 hours to induce apoptosis, and activation of Bcl-2, Bcl-xl, and caspase 3 was measured by western blot.

RESULTS

The upregulation of BAG5 in PC12 cells inhibited apoptosis and increased the expression of anti-apoptotic proteins, including Bcl-2 and Bcl-xl, after MPP(+) treatment. In addition, downregulation of BAG5 in PC12 cells enhanced apoptosis and decreased the expression of these proteins after MPP(+) treatment.

DISCUSSION

The data suggest that BAG5 inhibits MPP(+)-induced apoptosis through both endogenous and mitochondria-mediated pathways of apoptosis. Through this mechanism, the upregulation of BAG5 levels may occur through its anti-apoptotic activity in PD.

Terminalia chebula extract protects OGD-R induced PC12 cell death and inhibits lps induced microglia activation

Terminalia chebula, native to Southeast Asia, is a popular medicinal plant in Ayurveda. It has been previously reported to have strong antioxidant and anti-inflammatory efficacy. In this study, we aimed to investigate if fruit extract from T. chebula might protect neuronal cells against ischemia and related diseases by reduction of oxidative damage and inflammation in rat pheochromocytoma cells (PC12) using in vitro oxygen-glucose deprivation followed by reoxygenation (OGD-R) ischemia and hydrogen peroxide (H2O2) induced cell death. Cell survival was evaluated by a 2-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Free radical scavenging, lipid peroxidation and nitric oxide inhibition were measured by diphenyl-1-picrylhydrazyl (DPPH), thiobarbituric acid (TBA) and Griess reagent, respectively. We found that T. chebula extract: (1) increases the survival of cells subjected to OGD-R by 68%, and H2O2 by 91.4%; (2) scavenges the DPPH free radical by 96% and decreases malondialdehyde (MDA) levels from 237.0 ± 15.2% to 93.7 ± 2.2%; (3) reduces NO production and death rate of microglia cells stimulated by lipopolysaccharide (LPS). These results suggest that T. chebula extract has the potential as a natural herbal medicine, to protect the cells from ischemic damage and the possible mechanism might be the inhibition of oxidative and inflammatory processes.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Preventive effect of ethanol extract of Alpinia calcarata Rosc on Ehrlich's ascitic carcinoma cell induced malignant ascites in mice

OBJECTIVE

To explore cytotoxic activity of ethanol extract of Alpinia calcarata Rosc (EEAC) rhizome against Ehrlich ascites carcinoma (EAC) tumor bearing Swiss Albino mice.

METHODS

In the present study, its anti-neoplastic activity has been studied by monitoring parameters like tumor weight measurement, survival time, tumor cell growth inhibition, haematological characteristics etc.

RESULTS

It was found that EEAC at dose 8 mg/kg/day (i.p.) significantly decreased tumor weight (62.0%; P <0.01), increased life span (70.25%; P <0.01) and reduced tumor cell growth rate (85.7%; P <0.01) in comparison to those of EAC bearing mice. The plant extract also improved the depleted haematological parameters like RBC, WBC, Hb%, differential counts (e.g. lymphocytes, neutrophils, monocytes etc) of EAC bearing mice towards normal. The host toxic effects were not very high and recovered gradually towards normal within a few days after treatment.

CONCLUSIONS

EEAC exhibits potent in vivo cytotoxic activity against EAC tumor bearing Swiss Albino mice. So, the plant can be considered as a probable new source of antitumor agents.

Antioxidant activities of total phenols of Prunella vulgaris L. in vitro and in tumor-bearing mice

Prunella vulgaris L. (PV, Labiatae) is known as a self-heal herb. The different extracts of dried spikes were studied for the best antioxidant active compounds. The 60% ethanol extract (P-60) showed strong antioxidant activity based on the results of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid (ABTS˙+), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assay methods. High performance liquid chromatography (HPLC) and LC/MS analysis showed that the main active compounds in P-60 were phenols, such as caffeic acid, rosmarinic acid, rutin and quercetin. Total phenols were highly correlated with the antioxidant activity (R2=0.9988 in ABTS˙+; 0.6284 in DPPH and 0.9673 FRAP tests). P-60 could inhibit significantly the tumor growth in C57BL/6 mice. It can also been showed that increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) content in serum of tumor-bearing mice. These results suggested that P-60 extract had high antioxidant activity in vitro and in vivo and total phenols played an important role in antioxidant activity for inhibition of tumor growth.

Juglanone, a novel α-tetralonyl derivative with potent antioxidant activity from Juglans mandshurica

A novel alpha-tetralonyl derivative, juglanone, was isolated from the fresh unripe fruits of Juglans mandshurica. Its structure was determined by spectroscopic analyses and from chemical evidence. Juglanone exhibited significant antioxidant activity in assays for 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase-like activity with IC(50) values of 10.1 and 9.0 microM, respectively. It also showed moderate cytotoxic activity against HL-60 human myeloid leukemia with an IC(50) value of 19.7 microM.