Identification and Classification of Hubs in microRNA Target Gene Networks in Human Neural Stem/Progenitor Cells following Japanese Encephalitis Virus Infection.

RNA viruses are known to modulate host microRNA (miRNA) machinery for their own benefit. Japanese encephalitis virus (JEV), a neurotropic RNA virus, has been reported to manipulate several miRNAs in neurons or microglia. However, no report indicates a complete sketch of the miRNA profile of neural stem/progenitor cells (NSPCs), hence the focus of our current study. We used an miRNA array of 84 miRNAs in uninfected and JEV-infected human neuronal progenitor cells and primary neural precursor cells isolated from aborted fetuses. Severalfold downregulation of hsa-miR-9-5p, hsa-miR-22-3p, hsa-miR-124-3p, and hsa-miR-132-3p was found postinfection in both of the cell types compared to the uninfected cells. Subsequently, we screened for the target genes of these miRNAs and looked for the biological pathways that were significantly regulated by the genes. The target genes involved in two or more pathways were sorted out. Protein-protein interaction (PPI) networks of the miRNA target genes were formed based on their interaction patterns. A binary adjacency matrix for each gene network was prepared. Different modules or communities were identified in those networks by community detection algorithms. Mathematically, we identified the hub genes by analyzing their degree centrality and participation coefficient in the network. The hub genes were classified as either provincial (P < 0.4) or connector (P > 0.4) hubs. We validated the expression of hub genes in both cell line and primary cells through qRT-PCR after JEV infection and respective miR mimic transfection. Taken together, our findings highlight the importance of specific target gene networks of miRNAs affected by JEV infection in NSPCs.IMPORTANCE JEV damages the neural stem/progenitor cell population of the mammalian brain. However, JEV-induced alteration in the miRNA expression pattern of the cell population remains an open question, hence warranting our present study. In this study, we specifically address the downregulation of four miRNAs, and we prepared a protein-protein interaction network of miRNA target genes. We identified two types of hub genes in the PPI network, namely, connector hubs and provincial hubs. These two types of miRNA target hub genes critically influence the participation strength in the networks and thereby significantly impact up- and downregulation in several key biological pathways. Computational analysis of the PPI networks identifies key protein interactions and hubs in those modules, which opens up the possibility of precise identification and classification of host factors for viral infection in NSPCs.

miR-301a Regulates Inflammatory Response to Japanese Encephalitis Virus Infection via Suppression of NKRF Activity.

Microglia being the resident macrophage of brain provides neuroprotection following diverse microbial infections. Japanese encephalitis virus (JEV) invades the CNS, resulting in neuroinflammation, which turns the neuroprotective role of microglia detrimental as characterized by increased microglial activation and neuronal death. Several host factors, including microRNAs, play vital roles in regulating virus-induced inflammation. In the current study, we demonstrate that the expression of miR-301a is increased in JEV-infected microglial cells and human brain. Overexpression of miR-301a augments the JEV-induced inflammatory response, whereas inhibition of miR-301a completely reverses the effects. Mechanistically, NF-κB-repressing factor (NKRF) functioning as inhibitor of NF-κB activation is identified as a potential target of miR-301a in JEV infection. Consequently, miR-301a-mediated inhibition of NKRF enhances nuclear translocation of NF-κB, which, in turn, resulted in amplified inflammatory response. Conversely, NKRF overexpression in miR-301a-inhibited condition restores nuclear accumulation of NF-κB to a basal level. We also observed that JEV infection induces classical activation (M1) of microglia that drives the production of proinflammatory cytokines while suppressing alternative activation (M2) that could serve to dampen the inflammatory response. Furthermore, in vivo neutralization of miR-301a in mouse brain restores NKRF expression, thereby reducing inflammatory response, microglial activation, and neuronal apoptosis. Thus, our study suggests that the JEV-induced expression of miR-301a positively regulates inflammatory response by suppressing NKRF production, which might be targeted to manage viral-induced neuroinflammation.

Identification of new anti-inflammatory agents based on nitrosporeusine natural products of marine origin.

Nitrosporeusines A and B are two recently isolated marine natural products with novel skeleton and exceptional biological profile. Interesting antiviral activity of nitrosporeusines and promising potential in curing various diseases, evident from positive data from various animal models, led us to investigate their anti-inflammatory potential. Accordingly, we planned and synthesized nitrosporeusines A and B in racemic as well as enantiopure forms. The natural product synthesis was followed by preparation of several analogues, and all the synthesized compounds were evaluated for in vitro and in vivo anti-inflammatory potential. Among them, compounds 25, 29 and 40 significantly reduced levels of nitric oxide (NO), reactive oxygen species (ROS) and pro-inflammatory cytokines. In addition, these compounds suppressed several pro-inflammatory mediators including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-κB (NF-κB), and thereby can be emerged as potent anti-inflammatory compounds. Furthermore, all possible isomers of lead compound 25 were synthesized, characterized and profiled in same set of assays and found that one of the enantiomer (-)-25a was superior among them.

The host microRNA miR-301a blocks the IRF1-mediated neuronal innate immune response to Japanese encephalitis virus infection.

Effective recognition of viral components and the subsequent stimulation of the production of type I interferons (IFNs) is crucial for the induction of host antiviral immunity. The failure of the host to efficiently produce type I IFNs in response to infection by the Japanese encephalitis virus (JEV) is linked with an increased probability for the disease to become lethal. JEV is a neurotropic virus of the Flaviviridae family that causes encephalitis in humans. JEV infection is regulated by several host factors, including microRNAs, which are conserved noncoding RNAs that participate in various physiological and pathological processes. We showed that the JEV-induced expression of miR-301a led to inhibition of the production of type I IFN by reducing the abundances of the transcription factor IFN regulatory factor 1 (IRF1) and the signaling protein suppressor of cytokine signaling 5 (SOCS5). Mechanistically, induction of miR-301a expression during JEV infection required the transcription factor nuclear factor κB. In mouse neurons, neutralization of miR-301a restored the host innate immune response by enabling IFN-ß production, thereby restricting viral propagation. Inhibition of miR-301a in mouse brain rescued the production of IRF1 and SOCS5, increased the generation of IFN-ß, and reduced the extent of JEV replication, thus improving mouse survival. Thus, our study suggests that the JEV-induced expression of miR-301a assists viral pathogenesis by suppressing IFN production, which might be targeted by antiviral therapies.

Dynamic changes in global microRNAome and transcriptome reveal complex miRNA-mRNA regulated host response to Japanese Encephalitis Virus in microglial cells.

Microglia cells in the brain play essential role during Japanese Encephalitis Virus (JEV) infection and may lead to change in microRNA (miRNA) and mRNA profile. These changes may together control disease outcome. Using Affymetrix microarray platform, we profiled cellular miRNA and mRNA expression at multiple time points during viral infection in human microglial (CHME3) cells. In silico analysis of microarray data revealed a phased pattern of miRNAs expression, associated with JEV replication and provided unique signatures of infection. Target prediction and pathway enrichment analysis identified anti correlation between differentially expressed miRNA and the gene expression at multiple time point which ultimately affected diverse signaling pathways including Notch signaling pathways in microglia. Activation of Notch pathway during JEV infection was demonstrated in vitro and in vivo. The expression of a subset of miRNAs that target multiple genes in Notch signaling pathways were suppressed and their overexpression could affect JEV induced immune response. Further analysis provided evidence for the possible presence of cellular competing endogenous RNA (ceRNA) associated with innate immune response. Collectively, our data provide a uniquely comprehensive view of the changes in the host miRNAs induced by JEV during cellular infection and identify Notch pathway in modulating microglia mediated inflammation.

Total Syntheses and Biological Evaluation of (±)-Botryosphaeridione, (±)-Pleodendione, 4-epi-Periconianone B, and Analogues.

The total syntheses of (±)-botryosphaeridione, (±)-pleodendione, (±)-hoaensieremodione, 4-epi-periconianone B, and their analogues have been accomplished for the first time. All the synthesized target compounds were screened in neural anti-inflammatory assays using LPS induced microglia cells (N9). Among them, compounds 1 and 21 were identified as potential lead compounds for further profiling.

Amelioration of iron overload-induced liver toxicity by a potent antioxidant and iron chelator, Emblica officinalis Gaertn.

In liver, the major site of iron storage, iron overload is associated with oxidative damage of protein, lipid, and DNA and causes protein oxidation, lipid peroxidation, and rupture of hepatocytes, leading to cell death. Serum ferritin and liver iron content are the main forecasters of moderate to severe iron overload in the liver. The sequels of excess iron deposition in the liver are fibrosis and enhanced levels of serum enzymes and bilirubin markers. Emblica officinalis (EO) fruit extract was found efficient in lessening intraperitoneally injected iron dextran-induced liver toxicity in Swiss albino mice. Mice administered with different doses of 70% methanol extract of EO (50, 100, and 200 mg kg(-1) body weight) showed significant decrease in liver iron, serum ferritin, and serum enzyme levels, along with the decrease in lipid peroxidation, protein oxidation, and collagen content. The activity was further supported by its considerable iron chelation with half-maximal inhibitory concentration of 70.24 ± 2.74 µg ml(-1) and the protection on ferrous ion-mediated DNA breakdown with 50% protection ([P]50) of 1.04 ± 0.01 µg ml(-1). Simultaneously, the extract effectively induced the antioxidant enzyme levels and also exhibited the potential activity of reductive release of ferritin iron. These findings suggest that the EO extract may be used as a potent drug for the treatment of pathological sequences arisen in the iron overload-induced liver damage.

Heartwood extract of Acacia catechu induces apoptosis in human breast carcinoma by altering bax/bcl-2 ratio.

BACKGROUND: The heartwood extract of A. catechu, called pale catechu or "Katha" in Hindi has been widely used in traditional Indian medicinal system. Although various pharmacological properties of this plant had been reported previously, only a few were concerned with the anticancer activity of this plant. OBJECTIVE: The objective was to assess the in vitro anticancer and apoptosis inducing effect of 70% methanolic extract of "Katha" (ACME) on human breast adenocarcinoma cell line (MCF-7). MATERIALS AND METHODS: MCF-7 cell line was treated with increasing concentrations of ACME and cell viability was calculated. Flow cytometric methods were used to confirm the apoptosis promoting role of ACME. Morphological changes were then analysed using confocal microscopy. Western blotting was then performed to investigate the expression of apoptogenic proteins and to analyse the activation of caspases. RESULTS: ACME showed significant cytotoxicity to MCF-7 cells with an IC50 value of 288.85 ± 25.79 µg/ml. Flow cytometric analysis and morphological studies confirmed that ACME is able to induce apoptosis in MCF-7 cells. Furthermore, immunoblot results suggested the pathway of apoptosis induction by increasing Bax/Bcl-2 ratio which results in the activation of caspase-cascade and ultimately leads to the cleavage of Poly adeno ribose polymerase (PARP). CONCLUSION: These results provide the evidence that ACME is able to inhibit the proliferation of MCF-7 cells by inducing apoptosis through intrinsic pathway.

Role of pattern recognition receptors in flavivirus infections.

The flaviviral encephalitis has now become a major health concern in global scale. The efficient detection of viral infection and induction of the innate antiviral response by host's innate immune system are crucial to determine the outcome of infection. The intracellular pattern recognition receptors TLRs, RLRs, NLRs and CLRs play a central role in detection and initiation of robust antiviral response against flaviviral infection. Both cytoplasmic RLRs, RIG-I and MDA5 have been shown to be implicated in sensing flaviviral genomic RNA. Similarly among TLRs mainly TLR3 and TLR7 are known to respond in flaviviral infections as they are known to sense dsRNA and ssRNA moiety as their natural cognate ligand. Several studies have also shown the roles of NLRs and CLRs in mounting an innate antiviral response against flavivirus but, it is yet to be completely understood. Until now only few reports have implicated NLRs and CLRs in induction of antiviral and proinflammatory state following flaviviral infection. The current review therefore aims to comprehensively analyze past as well as current understanding on the role of PRRs in flaviviral infections.

Alteration of Bax/Bcl-2 ratio contributes to Terminalia belerica-induced apoptosis in human lung and breast carcinoma.

The objective of the present study was to assess the in vitro anticancer activity of 70% methanolic extract of Terminalia belerica (TBME) against human lung (A549) and human breast (MCF-7) carcinoma and its possible mechanism. TBME showed significant cytotoxicity to both A549 and MCF-7 cells, whereas, no cytotoxicity was found in non-malignant WI-38 cells. Flow cytometric analysis was then performed and 100 µg/ml of TBME was selected as the effective concentration inducing apoptosis in A549 and MCF-7. At this concentration, TBME caused DNA fragmentation pattern of apoptosis. Furthermore, mechanism of apoptosis induction was demonstrated using western blotting and Bax/Bcl-2 ratio in both types of the cells was found increased, which leads to the activation of caspase cascade along with the cleavage of PARP. These results suggested that TBME is able to induce anticancer effects on both lung and breast cancer cell lines through the modulation of Bcl-2 family proteins.

In vitro anticancer activity of Spondias pinnata bark on human lung and breast carcinoma.

Spondias pinnata, a commonly distributed tree in India, previously proven for various pharmacological properties and also reported for efficient anti-oxidant, free radical scavenging and iron chelating activity, continuing this, the present study is aimed to investigate the role of 70 % methanolic extract of S. pinnata bark (SPME) in promoting apoptosis in human lung adenocarcinoma cell line (A549) and human breast adenocarcinoma cell line (MCF-7). These two malignant cell lines and a normal cell line were treated with increasing concentrations of SPME and cell viability is calculated. SPME showed significant cytotoxicity to both A549 and MCF-7 cells with an IC50 value of 147.84 ± 3.74 and 149.34 ± 13.30 µg/ml, respectively, whereas, comparatively no cytotoxicity was found in normal human lung fibroblast cell line (WI-38): IC50 932.38 ± 84.44 µg/ml. Flow cytometric analysis and confocal microscopic studies confirmed that SPME is able to induce apoptosis in both malignant cell lines. Furthermore, immunoblot result proposed the pathway of apoptosis induction by increasing Bax/Bcl-2 ratio in both cell types, which results in the activation of the caspase-cascade and ultimately leads to the cleavage of Poly adeno ribose polymerase. For the first time this study proved the anticancer potential of SPME against human lung and breast cancer by inducing apoptosis through the modulation of Bcl-2 family proteins. This might take S. pinnata in light to investigate it for further development as therapeutic anticancer source.

Study of the protective effects of Katha (Heartwood Extract of Acacia catechu) in liver damage induced by iron overload.

This study evaluated the ameliorating effect of 70% methanol extract of Acacia catechu heartwood, or Katha (ACME) on liver injury induced by iron overload. Iron overload in mice was caused by intraperitoneal administration of 100 mg/kg iron-dextran. ACME was administered orally for 21 days, starting from the day after the first iron-dextran injection. The biochemical markers of hepatic damage and liver iron, protein carbonyl, and hydroxyproline contents were measured in response to the oral administration of ACME. Apart from those, the release of iron from ferritin by ACME was further assessed to determine the efficiency of ACME as an iron-chelating drug. Treatment with different doses of ACME (50, 100, and 200 mg/kg body weight) showed dose-dependent reductions in liver iron, lipid peroxidation, protein oxidation, liver fibrosis, serum enzymes, and ferritin. The antioxidant enzymes levels were enhanced and the reductive release of ferritin iron increased significantly with gradually increasing concentrations of ACME. These results indicate that ACME has a potent hepatoprotective action against hepatic damage induced by iron overload in mice, probably by ameliorating the antioxidant defense activities and reductively releasing ferritin iron.

Anti-oxidative protection against iron overload-induced liver damage in mice by Cajanus cajan (L.) Millsp. leaf extract.

In view of the contribution of iron deposition in the oxidative pathologic process of liver disease, the potential of 70% methanolic extract of C. cajan leaf (CLME) towards antioxidative protection against iron-overload-induced liver damage in mice has been investigated. DPPH radical scavenging and protection of Fenton reaction induced DNA damage was conducted in vitro. Post oral administration of CLME to iron overloaded mice, the levels of antioxidant and serum enzymes, hepatic iron, serum ferritin, lipid peroxidation, and protein carbonyl and hydroxyproline contents were measured, in comparison to deferasirox treated mice. Oral treatment of the plant extract effectively lowered the elevated levels of liver iron, lipid peroxidation, protein carbonyl and hydroxyproline. There was notable increment in the dropped levels of hepatic antioxidants. The dosage of the plant extract not only made the levels of serum enzymes approach normal value, but also counteracted the overwhelmed serum ferritin level. The in vitro studies indicated potential antioxidant activity of CLME. The histopathological observations also substantiated the ameliorative function of the plant extract. Accordingly, it is suggested that Cajanus cajan leaf can be a useful herbal remedy to suppress oxidative damage caused by iron overload.

Spondias pinnata stem bark extract lessens iron overloaded liver toxicity due to hemosiderosis in Swiss albino mice.

The present study was designed to evaluate the ameliorating effect of 70% methanol extract of Spondias pinnata (SPME) on iron overload induced liver injury. Iron overload was induced by intraperitoneal administration of iron-dextran into mice and resulting liver damage was manifested by significant rise in serum enzyme markers (ALT, AST, ALP and bilirubin) and reduction in liver antioxidants (SOD, CAT, GST and GSH). Hepatic iron, serum ferritin, lipid peroxidation, protein carbonyl and hydroxyproline contents were measured in response to the oral administration of SPME of different doses (50, 100 and 200 mg/kg body weight). In order to determine the efficiency as iron chelating drug, the release of iron from ferritin by SPME was further studied. Enhanced levels of antioxidant enzymes were detected in SPME treated mice. SPME produced a dose dependent inhibition of lipid peroxidation, protein oxidation, liver fibrosis; and levels of serum enzyme markers and ferritin were also reduced dose dependently. The liver iron content was also found to be less in SPME treated group compared to control group. The reductive release of ferritin iron was augmented significantly after dose dependent addition of SPME. The ameliorating effect of SPME on damaged liver was furthermore supported by the histopathological studies that showed improved histological appearances. In conclusion, the present results demonstrate the hepatoprotective efficiency of SPME in iron intoxicated mice, and hence possibly useful as iron chelating drug for iron overload diseases.

Reducing power and iron chelating property of Terminalia chebula (Retz.) alleviates iron induced liver toxicity in mice.

BACKGROUND: The 70% methanol extract of Terminalia chebula Retz. fruit (TCME) was investigated for its in vitro iron chelating property and in vivo ameliorating effect on hepatic injury of iron overloaded mice. METHODS: The effect of fruit extract on Fe2+-ferrozine complex formation and Fe2+ mediated pUC-18 DNA breakdown was studied in order to find the in vitro iron chelating activity. Thirty-six Swiss Albino mice were divided into six groups of: blank, patient control and treated with 50, 100, 200 mg/kg b.w. of TCME and desirox (standard iron chelator drug with Deferasirox as parent compound). Evaluations were made for serum markers of hepatic damage, antioxidant enzyme, lipid per oxidation and liver fibrosis levels. The reductive release of ferritin iron by the extract was further studied. RESULTS: In vitro results showed considerable iron chelation with IC50 of 27.19 ± 2.80 µg/ml, and a significant DNA protection with [P]50 of 1.07 ± 0.03 µg/ml along with about 86% retention of supercoiled DNA. Iron-dextran injection (i.p.) caused significant increase in the levels of the serum enzymes, viz., alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), alkaline phosphatase (ALP) and Bilirubin, which were subsequently lowered by oral administration of 200 mg/kg b.w. dose of the fruit extract by 81.5%, 105.88%, 188.08% and 128.31%, respectively. Similarly, treatment with the same dose of the extract was shown to alleviate the reduced levels of liver antioxidant enzyme superoxide dismutase, catalase, glutathione S-transferase and non-enzymatic reduced glutathione, by 49.8%, 53.5%, 35.4% and 11% respectively, in comparison to the iron overloaded mice. At the same time, the fruit extract effectively lowered the iron-overload induced raised levels of lipid per oxidation, protein carbonyl, hydroxyproline and liver iron by 49%, 67%, 67% and 26%, respectively, with oral treatment of 200 mg/kg b.w. dose of TCME. The fruit extract also showed potential activity for reductive release of ferritin iron. CONCLUSIONS: These findings suggest that Terminalia chebula extract may contain active substances capable of lessening iron overload induced toxicity, and hence possibly be useful as iron chelating drug for iron overload diseases.

Hepatoprotective Potential of Caesalpinia crista against Iron-Overload-Induced Liver Toxicity in Mice.

The present study was carried out to evaluate the ameliorating effect of Caesalpinia crista Linn. (CCME) extract on iron-overload-induced liver injury. Iron overload was induced by intraperitoneal administration of iron dextran into mice. CCME attenuated the percentage increase in liver iron and serum ferritin levels when compared to control group. CCME also showed a dose-dependent inhibition of lipid peroxidation, protein oxidation, and liver fibrosis. The serum enzyme markers were found to be less, whereas enhanced levels of liver antioxidant enzymes were detected in CCME-treated group. In presence of CCME, the reductive release of ferritin iron was increased significantly. Furthermore, CCME exhibited DPPH radical scavenging and protection against Fe(2+)-mediated oxidative DNA damage. The current study confirmed the hepatoprotective effect of CCME against the model hepatotoxicant iron overload and the activity is likely related to its potent antioxidant and iron-chelating property.

Assessment of the Antioxidant and Reactive Oxygen Species Scavenging Activity of Methanolic Extract of Caesalpinia crista Leaf.

"Oxidative stress" is initiated by reactive oxygen species (ROS), which are responsible for majority of the diseases. However, antioxidants with ROS scavenging ability may have great relevance in the prevention of oxidative stress. The present study was undertaken, using a 70% methanolic extract of Caesalpinia crista leaves, to examine different in vitro tests in diversified fields including total antioxidant activity, scavenging activities for various ROS, iron chelating activity and phenolic and flavonoid contents. Total antioxidant activity was evaluated as trolox equivalent antioxidant capacity value of 0.546 ± 0.014. The extract was investigated for different ROS scavenging activities and IC(50) values were found to be 0.44 ± 0.1 mg/ml, 24.9 ± 0.98 µg/ml, 33.72 ± 0.85 µg/ml, 61.13 ± 3.24 µg/mL and 170.51 ± 4.68 µg/mL for hydroxyl, superoxide, nitric oxide, singlet oxygen and hypochlorous acid, respectively; however, no significant results were obtained in scavenging of hydrogen peroxide and peroxynitrite anion. The extract was found to be a potent iron chelator with IC(50) = 279.85 ± 4.72 µg/mL. The plant extract (100 mg) yielded 50.23 ± 0.003 mg/mL gallic acid equivalent phenolic content and 106.83 ± 0.0003 mg/mL quercetin equivalent flavonoid content. In the in vivo experiments, the extract treatment showed significant increase in the level of superoxide dismutase, catalase, glutathione-S-transferase and reduced glutathione. In a word, it may be concluded that 70% methanol extract of C. crista leaves acts as an antioxidant and ROS scavenger; which may be due to the presence of phenolic and flavonoid compounds.

Comparative study of the antioxidant and reactive oxygen species scavenging properties in the extracts of the fruits of Terminalia chebula, Terminalia belerica and Emblica officinalis.

BACKGROUND: Cellular damage caused by reactive oxygen species (ROS) has been implicated in several diseases, and hence natural antioxidants have significant importance in human health. The present study was carried out to evaluate the in vitro antioxidant and reactive oxygen species scavenging activities of Terminalia chebula, Terminalia belerica and Emblica officinalis fruit extracts. METHODS: The 70% methanol extracts were studied for in vitro total antioxidant activity along with phenolic and flavonoid contents and reducing power. Scavenging ability of the extracts for radicals like DPPH, hydroxyl, superoxide, nitric oxide, hydrogen peroxide, peroxynitrite, singlet oxygen, hypochlorous acid were also performed to determine the potential of the extracts. RESULTS: The ability of the extracts of the fruits in exhibiting their antioxative properties follow the order T. chebula >E. officinalis >T. belerica. The same order is followed in their flavonoid content, whereas in case of phenolic content it becomes E. officinalis >T. belerica >T. chebula. In the studies of free radicals' scavenging, where the activities of the plant extracts were inversely proportional to their IC50 values, T. chebula and E. officinalis were found to be taking leading role with the orders of T. chebula >E. officinalis >T. belerica for superoxide and nitric oxide, and E. officinalis >T. belerica >T. chebula for DPPH and peroxynitrite radicals. Miscellaneous results were observed in the scavenging of other radicals by the plant extracts, viz., T. chebula >T. belerica >E. officinalis for hydroxyl, T. belerica >T. chebula >E. officinalis for singlet oxygen and T. belerica >E. officinalis >T. chebula for hypochlorous acid. In a whole, the studied fruit extracts showed quite good efficacy in their antioxidant and radical scavenging abilities, compared to the standards. CONCLUSIONS: The evidences as can be concluded from the study of the 70% methanol extract of the fruits of Terminalia chebula, Terminalia belerica and Emblica officinalis, imposes the fact that they might be useful as potent sources of natural antioxidant.

Antioxidant and free radical scavenging activity of Spondias pinnata.

BACKGROUND: Many diseases are associated with oxidative stress caused by free radicals. Current research is directed towards finding naturally-occurring antioxidants of plant origin. The aim of the present study was to evaluate the in vitro antioxidant activities of Spondias pinnata stem bark extract. METHODS: A 70% methanol extract of Spondias pinnata stem bark was studied in vitro for total antioxidant activity, for scavenging of hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, singlet oxygen and hypochlorous acid, and for iron chelating capacity, reducing power, and phenolic and flavonoid contents. RESULTS: The extract showed total antioxidant activity with a trolox equivalent antioxidant concentration (TEAC) value of 0.78 +/- 0.02. The IC50 values for scavenging of free radicals were 112.18 +/- 3.27 microg/ml, 13.46 +/- 0.66 microg/ml and 24.48 +/- 2.31 microg/ml for hydroxyl, superoxide and nitric oxide, respectively. The IC50 for hydrogen peroxide scavenging was 44.74 +/- 25.61 mg/ml. For the peroxynitrite, singlet oxygen and hypochlorous acid scavenging activities the IC50 values were 716.32 +/- 32.25 microg/ml, 58.07 +/- 5.36 microg/ml and 127.99 +/- 6.26 microg/ml, respectively. The extract was found to be a potent iron chelator with IC50 = 66.54 +/- 0.84 microg/ml. The reducing power was increased with increasing amounts of extract. The plant extract (100 mg) yielded 91.47 +/- 0.004 mg/ml gallic acid-equivalent phenolic content and 350.5 +/- 0.004 mg/ml quercetin-equivalent flavonoid content. CONCLUSION: The present study provides evidence that a 70% methanol extract of Spondias pinnata stem bark is a potential source of natural antioxidants.