[Show abstract][Hide abstract] ABSTRACT: The sensitivity of human Burkitt's lymphoma cells to rituximab (Rtx) and tositumomab (Tst) was assessed on cells expressing different levels of CD20 on surface. Cells that harbor low CD20 levels may resists against therapeutics response to CD20-specific antibodies. We postulated that, radiation-induced modulation of CD20 surface levels may play a crucial and central role in determining the relative efficacy of rituximab and tositumomab in treating Burkitt's lymphoma disease. Here, we examined the γ-radiation-induced CD20 expression in the Burkitt lymphoma cell line 'Daudi' and the relation of differential levels of CD20 with anti-CD20 mAbs mediated cell death.
PLoS ONE 11/2014; 9(11):e111113. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fourteen saxicolous lichens from trans-Himalayan Ladakh region were identified by morpho-anatomical and chemical characteristics. The n-hexane, methanol and water extracts of the lichens were evaluated for their antioxidant capacities. The lichen extracts showing high antioxidant capacities and rich phenolic content were further investigated to determine their cytotoxic activity on human HepG2 and RKO carcinoma cell lines. The ferric reducing antioxidant power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging capacities and β-carotene-linoleic acid bleaching property exhibited analogous results where the lichen extracts showed high antioxidant action. The lichen extracts were also found to possess good amount of total proanthocyanidin, flavonoid and polyphenol. The methanolic extract of Lobothallia alphoplaca exhibited highest FRAP value. Methanolic extract of Xanthoparmelia stenophylla showed the highest ABTS radical scavenging capacity. The n-hexane extract of Rhizoplaca chrysoleuca exhibited highest DPPH radical scavenging capacity. Highest antioxidant capacity in terms of β-carotene linoleic acid bleaching property was observed in the water extract of Xanthoria elegans. Similarly, Melanelia disjuncta water extract showed highest NO scavenging capacity. Among n-hexane, methanol and water extracts of all lichens, the methanolic extract of Xanthoparmelia mexicana showed highest total proanthocyanidin, flavonoid and polyphenol content. From cytotoxic assay, it was observed that the methanolic extracts of L. alphoplaca and M. disjuncta were exhibiting high cytotoxic effects against cancer cell growth. Similarly, the water extract of Dermatocarpon vellereum, Umbilicaria vellea, X. elegans and M. disjuncta and the methanolic extract of M. disjuncta and X. stenophylla were found to possess high antioxidant capacities and were non-toxic and may be used as natural antioxidants for stress related problems. Our studies go on to prove that the unique trans-Himalayan lichens are a hitherto untapped bioresource with immense potential for discovery of new chemical entities, and this biodiversity needs to be tapped sustainably.
PLoS ONE 06/2014; 9(6):e98696. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A thermophilic bacterium, designated as RH 127, was isolated from mud volcano (Baratang Islands) of Andaman region, India (12°07'N 92°47'E/12.117°N 92.783°E) for the first time. Biochemical tests and 16S rRNA gene sequencing indicate that it belongs to the genus Geobacillus. The strain showed 98% confirmed 16S rRNA gene sequence homology with Geobacillus toebii. The bacteria was extracted in various solvent systems and three different fractions prepared. In the present study, antioxidant and radioprotective activity of extracts (INM-7860, INM-7861, and INM-7862) of bacterium G. toebii (strain RH 127) were evaluated. The fractions were evaluated for their introspective comparison of the relative antioxidant efficiency. The antioxidative activities, DPPH radical scavenging effects, hydroxyl radical scavenging effects, membrane protection, antihemolytic activity, and linoleic acid degradation efficacies were assayed. INM-7861 and INM-7862 activated NF-κB expression, as evidenced by reporter assay studies, and thereby contributed to overall radioprotective effect. INM-7862 exhibited best results. This study explicitly shows that the extracts of G. toebii have immense potential as a radiation countermeasure agent.
Molecular and Cellular Biochemistry 04/2011; 353(1-2):243-50. · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study is the first report of the radiomodulatory effects of Psoralea corylifolia Linn. The extract (IBG-RA-26) prepared from P. corylifolia was chemically analysed by HPLC, LC-MS/MS and NMR. The total polyphenolic content of IBG-RA-26 was 0.287 mg/ml of quercetin equivalents. IBG-RA-26 exhibited a dose-dependent increase in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. It exhibited comparable (> 50%) site-specific and non-site-specific hydroxyl radical scavenging activity in higher concentration ranges (500-1000 microg/ml), while at lower concentrations (5-50 microg/ml) it exhibited significantly (p < 0.05) higher non-site-specific scavenging ability compared to site-specific activity. Nitric oxide scavenging activity of IBG-RA-26 (5-1000 microg/ml) increased in a concentration-dependent manner, while maximum superoxide ion scavenging ability (79%) was observed at 50 microg/ml. The electron donation potential of IBG-RA-26 was found to be higher than that of ascorbic acid at lower concentrations (up to 5 microg/ml). Analysis of the ability of IBG-RA-26 to protect membranes against gamma-radiation, utilizing an artificial membrane system (liposome), revealed a significant (p < 0.05) decrease in the formation of malondialdehyde (MDA) as a function of the concentration of IBG-RA-26. Radiation-induced lysis of human erythrocytes was monitored and efficacy of IBG-RA-26 was tested in the concentration range 25-1000 microg/ml, with significant protective efficacy observed in the range 25-50 microg/ml. IBG-RA-26 rendered significant (p < 0.05) protection against radiation (0.25 kGy)-induced DNA damage. EPR spectroscopy was used to investigate the DPPH radical scavenging capacity of IBG-RA-26. IBG-RA-26 exhibited a good DPPH radical scavenging capacity in a concentration-dependent manner. By direct EPR spectroscopy we have also demonstrated the possible formation of free radical species in a solution of IBG-RA-26. The wide spectrum of radioprotective and antioxidant properties exhibited by IBG-RA-26 indicate that P. corylifolia has potential as a radiomodulatory agent.
Zeitschrift fur Naturforschung C 01/2011; 66(1-2):35-46. · 0.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT. Management of radiation-induced reactive oxygen/nitrogen species requires a holistic approach to mitigate the deleterious effects of free radicals. Flora of the Himalayas, which prevails under extreme climatic conditions, has been explored for its potential utility to develop radioprotective drugs. The Himalayan high altitude medicinal plant, Podophyllum hexandrum Royle, was selected on the basis of its unique properties, and a novel fractionated nonpolar extract (REC-2003) was prepared and evaluated for radioprotective efficacy, in vitro as well as in vivo. The free radical scavenging activity of REC-2003 was found to be > 75% (20 μg/ml) with maximum superoxide scavenging activity (57.56 ± 1.38%) recorded at 1 mg/ml concentration (tetrazolium-based estimation). More than 30% inhibition of nitric oxide radicals was observed at concentrations > 0.5 mg/ml, while hydroxyl radical scavenging activity (deoxy-D-ribose assay) exhibited a dose-dependent (100-600 μg/ml) increase. Significantly high (90%) protection to human erythrocytes was observed at 75 μg/ml, which was found to be the most optimized dose. Similarly, more than 90% inhibition was observed against lipid peroxidation (evaluated by estimating levels of malondialdehyde). The significant antihemolytic potential of REC-2003 could be attributed to its ability to scavenge free radicals, reduce peroxidative stress on lipid membranes, and render protection to DNA (evaluated using plasmid relaxation assay). All these activities holistically contributed toward the radioprotective ability. REC-2003 (8 mg/kg BW; intraperitoneal (i.p.), -30 min) rendered > 80% total-body protection in Swiss Albino Strain 'A' mice [against lethal radiation (10 Gy)] in a 30-day survival assay. Phytochemical characterization of the constituents of REC-2003 revealed the presence of polyphenolics (flavonoids). The characterized constituents also included the aryl-tetralin lignans like podophyllotoxin, its glycoside, 4'-demethyl derivative, and epi-podophyllotoxin. The optimized requisite single dose (8 mg/KgBW; i.p., -30 min) for obtaining significant radioprotection is reasonably low and establishes its future utility as a dietary supplement in the medical management of free radical-mediated diseases and specifically for rescue missions during nuclear and radiological emergencies (NREs).
Journal of Dietary Supplements 03/2010; 7(1):31-50.
[Show abstract][Hide abstract] ABSTRACT: Silymarin, a purified extract of seeds of Silybum marianum L. and well known for its hepatoprotective abilities, has been evaluated for inherent utility as a radioprotective agent. A fraction (INM-7035) was authenticated by characterizing the percentage composition of silybin A and B (39.9% and 57.4%). Free radical scavenging activities of INM-7035 against superoxide radicals (>68%), hydroxyl radicals (>33.75%), DPPH (67.2%), and ABTS (32.4%) were also evaluated. The fraction chelated (>30%) ferrous ions, thereby able to restrict amplification. INM-7035 exhibited >50% peroxyl radical scavenging activity in the lipid phase along with dose-dependent (R2 = 0.990) reducing power in the aqueous phase. Radiation-induced free radical flux can lead to disruption of biomolecules like membrane lipids. INM-7035 completely inhibited lipid peroxidative stress in case of membranes against supralethal radiation stress in the liposomal system. The ability of INM-7035 to modulate the levels of NF-kappaB, indicated its inherent potential as a radioprotective bioactive constituent.
Zeitschrift fur Naturforschung C 01/2010; 65(5-6):337-46. · 0.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Increasing the levels of CD20 expression in cells that harbor low CD20 levels may enhance their responsiveness to CD20-specific antibody therapies. Here, we examined the regulation of CD20 expression after treatment with 0.5-2.0 Gy X-irradiation and hydrogen peroxide (H(2)O(2)), in the presence or absence of known antioxidants, in the Burkitt lymphoma cell lines Daudi and Raji. Irradiation of cells enhanced cell-surface CD20 expression; the kinetics and extent of this change were cell-type specific and time-dependent. The kinetics of reactive oxygen species generation and changes in mitochondrial membrane potential after irradiation were also correlated with changes in CD20 expression. Raji and Daudi cells treated with H(2)O(2) showed a 2-to 2.5-fold increase in CD20 expression at 12 and 20 h, respectively. Buthionine sulfoximine, which depletes glutathione, also increased surface CD20, whereas antioxidants, such as PEG-catalase, PEG-SOD, vitamin C, and amifostine, decreased CD20 expression induced by radiation or H(2)O(2). The antioxidant-mediated decrease in CD20 expression induced by radiation or H(2)O(2) suggests a mechanism involving redox regulation. These results demonstrate the critical role of radiation-induced oxidative stress in CD20 expression and may have implications for defining and improving the efficacy of CD20-targeted antibody therapy and radioimmunotherapy.
Free Radical Biology and Medicine 03/2008; 44(4):614-23. · 5.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mammalian cells undergo cell cycle arrest in response to DNA damage through multiple checkpoint mechanisms. One such checkpoint pathway maintains genomic integrity by delaying mitotic progression in response to genotoxic stress. Transition though the G2 phase and entry into mitosis is considered to be regulated primarily by cyclin B1 and its associated catalytically active partner Cdk1. While not necessary for its initiation, the p130 and Rb-dependent target genes have emerged as being important for stable maintenance of a G2 arrest. It was recently demonstrated that by interacting with p130, E2F4 is present in the nuclei and plays a key role in the maintenance of this stable G2 arrest. Increased E2F4 levels and its translocation to the nucleus following genotoxic stress result in downregulation of many mitotic genes and as a result promote a G0-like state. Irradiation of E2F4-depleted cells leads to enhanced cellular DNA double-strand breaks that may be measured by comet assays. It also results in cell death that is characterized by caspase activation, sub-G1 and sub-G2 DNA content, and decreased clonogenic cell survival. Here we review these recent findings and discuss the mechanisms of G2 phase checkpoint activation and maintenance with a particular focus on E2F4.
[Show abstract][Hide abstract] ABSTRACT: The development of radioprotective agents has been the subject of intense research in view of their potential for use within a radiation environment, such as space exploration, radiotherapy and even nuclear war. However, no ideal, safe synthetic radioprotectors are available to date, so the search for alternative sources, including plants, has been on going for several decades. In Ayurveda, the traditional Indian system of medicine, several plants have been used to treat free radical-mediated ailments and, therefore, it is logical to expect that such plants may also render some protection against radiation damage. A systematic screening approach can provide leads to identifying potential new candidate drugs from plant sources, for mitigation of radiation injury. This article reviews some of the most promising plants, and their bioactive principles, that are widely used in traditional systems of medicine, and which have rendered significant radioprotection in both in vitro and in vivo model systems. Plants and their constituents with pharmacological activities that may be relevant to amelioration of radiation-mediated damage, including antiemetic, antiinflammatory, antioxidant, cell proliferative, wound healing and haemopoietic stimulatories are also discussed.
Phytotherapy Research 02/2005; 19(1):1-22. · 2.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The whole extract of the fresh berries of Hippophae rhamnoides L. (RH-3), which has been reported to provide protection to whole mice, various tissues, cells and cell organelles against lethal irradiation, was further investigated for its effects on mitochondria isolated from mouse liver. Superoxide anion, reduced (GSH) and oxidized glutathione (GSSG) levels, NADH-ubiquinone oxidoreductase (complex I), NADH-cytochrome c oxidoreductase (complex I/II), succinate-cytochrome c oxidoreductase (complex II/III), mitochondrial membrane potential (MMP), lipid peroxidation (LPx) and protein oxidation (PO) were determined for RH-3-mediated radioprotective manifestation. Pre-irradiation treatment of mice with RH-3 (30 mg kg(-1,) i. p.; single dose; -30 min) significantly inhibited the radiation-induced increase in superoxide anions, GSSG, thiobarbituric acid reactive substances (TBARS), complex I, complex I/III activity and MMP maximally at 4 h (P < 0.05). This treatment inhibited the oxidation of proteins (P < 0.05) at all the time periods studied here. This study suggests that pre-irradiation treatment of mice with RH-3 protects the functional integrity of mitochondria from radiation-induced oxidative stress.
Journal of Pharmacy and Pharmacology 02/2005; 57(1):135-43. · 2.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study was undertaken to investigate whether RP-1 treatment protected mitochondrial system against radiation damage and also to unravel the mechanism associated with this process. Radioprotection of mitochondrial system by Podophyllum hexandrum (RP-1) was investigated to understand its mechanism of action. Levels of superoxide anion (O2-), reduced or oxidized glutathione (GSH or GSSG), thiobarbituric acid reactive substance (TBARS), protein carbonyl (PC), ATP, NADH-ubiquinone oxidoreductase (complex-I), NADH-cytochrome c oxidoreductase (complex I/II), succinate-cytochrome c oxidoreductase (complex II/III) and mitochondrial membrane potential (MMP) were studied in mitochondria isolated from liver of mice belonging to various treatment groups. Whole body y-irradiation (10 Gy) significantly (p < 0.01) increased the formation of O2-, PC, and TBARS, upto 24 h as compared to untreated control. RP-1 treatment (200 mg/kg b.w.) to mice 2 h before irradiation reduced the radiation-induced O2- generation within 4 h and formation of TBARS and PC upto 24 h significantly (p < 0.01). Singularly irradiation or RP-1 treatment significantly (p < 0.01) increased the levels of glutathione within an hour, as compared to untreated control. Pre-irradiation administration of RP-1 enhanced levels of GSH induced increase in complex I (upto 16 h), complex I/III (4 h) complex II/III activity (upto 24 h; p < 0.01) and inhibited the radiation-induced decrease in MMP significantly (24 h; p < 0.01). The present study indicates that RP-1 itself modulates several mitichondrial perameters due to its influence on the biochemical milieu within and outside the cells. However, RP-1 treatment before irradiation modulates radiation induced perturbations such as the increase in electron transport chain enzyme activity, formation of O2-, TBARS and PC to offer radioprotection.
Molecular and Cellular Biochemistry 11/2004; 266(1-2):65-77. · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Radioprotection by an aqueous extract of Podophyllum hexandrum (RP-1) was investigated in HepG2 cells by evaluating colony forming efficacy (CFE), redox status of mitochondria, reactive oxygen species (ROS), generation of nitric oxide (NO), peroxidation of lipids and intracellular glutathione. Lower concentrations of RP-1 (0.1 and 1 microg/ml) rendered maximum radioprotection when administered 1 or 2 h before irradiation. Higher concentrations (5 and 10 microg/ml) however were less effective when administered 1 or 2 h before irradiation, but were more effective with increased time intervals (4 or 8 h) between RP-1 administration and irradiation. RP-1 pre-treatment also significantly inhibited radiation-induced MTT reduction in a concentration and time-dependent manner by decreasing gamma radiation-induced leakage of electrons from electron transport chain. Pre-irradiation administration of RP-1 significantly reduced both ROS and NO generation and enhanced glutathione levels, thereby inhibiting lipid peroxidation.
Molecular and Cellular Biochemistry 09/2003; 250(1-2):27-40. · 2.39 Impact Factor