International Journal of Biological Macromolecules 68 (2014) 209–214

Contents lists available at ScienceDirect

International Journal of Biological Macromolecules journal homepage: www.elsevier.com/locate/ijbiomac

Astragalus polysaccharide ameliorates ionizing radiation-induced oxidative stress in mice Yao Liu, Fang Liu, Ya Yang, Di Li, Jun Lv, Yangjin Ou, Fengjun Sun, Jianhong Chen, Ying Shi ∗ , Peiyuan Xia ∗ Department of Pharmacy, Southwest Hospital, Third Military Medical University, 29 Gao Tan Yan Street, Chongqing 400038, Shapingba District, China

a r t i c l e

i n f o

Article history: Received 19 February 2014 Received in revised form 28 April 2014 Accepted 4 May 2014 Available online 10 May 2014 Keywords: Astragalus polysaccharide Radiation Oxidative stress

a b s t r a c t Radioprotective compounds from plant resources may represent safe and cost-effective prophylactic and therapeutic agents. This study was designed to investigate the protective effect of polysaccharide derived from the dried roots of the Astragalus spp. (APS) against ionizing radiation (IR) injury in liver and to explore its role in radiation-induced oxidative stress using a mouse model. Prior to 60 Co ␥-irradiation (5 Gy, single dose), mice received 7 days of APS at low, mid and high doses (50, 100 or 200 mg/kg/day, respectively; n = 6 each group), vehicle alone (5 mL normal saline orally/daily; n = 6). A non-irradiated control group (n = 6) received the 7-day distilled water regimen only. At 24 h post-irradiation, the APS pre-treated mice showed significantly decreased alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase levels, and NF-␬B expression. All APS-treated mice also showed attenuation of the IRinduced increase in thiobarbituric acid reactive substance and resolution of the IR-induced decreases in superoxide dismutase, catalase and glutathione activities (all p < 0.05). High dose APS pre-treatment led to remarkably less morphologic features of IR-induced hepatic and pulmonary injury. Thus, APS exerts protective effects against IR-induced injury in liver in mice, and the related molecular mechanism may involve suppressing the radiation-induced oxidative stress reaction. © 2014 Elsevier B.V. All rights reserved.

1. Introduction Despite the relative safety and efficiency of today’s radiationbased technologies and stricter regulation of radiation sources, many routine activities of modern life remain sources of exposure to ionizing radiation, including practices related to the medical (diagnostic and therapeutic exposures), industrial (workplace exposures) and recreational (air travel and environmental exposures) fields [1–3]. Ionizing radiation can damage human tissue either directly, by interacting with target molecules, or indirectly, by forming hydroxyl radical (OH• ), hydroperoxyl radial (HO2 • ) or superoxide anion (O2 •− ), which can then react with cellular macromolecules and cause cellular dysfunction and death [4]. Radioprotective compounds from plant resources may represent safe (possibly producing fewer side effects in patients) and costeffective prophylactic and therapeutic agents [5–8]. The astragalus compound, derived from the dried roots of the Astragalus spp. mongolicus and membranaceus, is a well-established traditional Chinese medicine and has been used in treatment of the

common cold, diarrhea, fatigue, anorexia, and cardiac diseases for more than 2000 years. The roots of the Astragalus spp. contain multiple bioactive compounds, such as flavones, polysaccharides and saponins. The Astragalus polysaccharide (APS) itself has a broad range of demonstrated pharmacological properties, including anticancer, anti-inflammatory, immunomodulatory and antioxidant effects [9–12]. Extensive research efforts have been put forth to develop effective radioprotective agents for use within environments with known risk of radiation exposure, such as those encountered in space exploration and radiotherapy. No published study to date, though, has addressed the protective potential of APS against radiation-induced oxidative stress. Therefore, the current study was designed to determine the impact of oxidative stress on irradiation (IR)-induced tissue damage in liver tissue and to investigate the possible radioprotective effect of prophylactic APS administration on IR-induced damage of these tissues. 2. Materials and methods 2.1. Chemicals

∗ Corresponding authors. E-mail addresses: [email protected], [email protected] (Y. Shi), py [email protected] (P. Xia). http://dx.doi.org/10.1016/j.ijbiomac.2014.05.001 0141-8130/© 2014 Elsevier B.V. All rights reserved.

The lipid peroxidation (LPO), thiobarbituric acid reactive substance (TRABS), superoxide dismutase (SOD), glutathione

210

Y. Liu et al. / International Journal of Biological Macromolecules 68 (2014) 209–214

S-transferase (GST), alanine (ALT), aspartate (AST), and lactate dehydrogenase (LDH) were purchased form Nanjing Jiancheng Co. Ltd. (Nanjing, China). All chemicals were of analytical grade. 2.2. Isolation of astragalus polysaccharides The protocol of preparation APS was performed by following the method as described elsewhere [13]. The dried, pulverized Astragalus membranaceus (purchased form Dalian, China) was immersed in distilled water (the ratio of AM and distilled water was 1:20) for 24 h and extracted 3 times with distilled water for 1 h each in a boiling water bath. Sevage reagents (ratio of chloroform and n-butanol was 4:1) were used to remove protein constituents. Then the resultant liquor was precipitated with 3 times volume of 95% ethanol. Precipitation of polysaccharides was collected by centrifugation at 5000 × g for 10 min was dissolved in distilled water, ethanol was added to final concentration of 25% to settle. The precipitate was discarded and the supernatant was added with 95% ethanol to final concentration of 75% and stood at 4 ◦ C for 24 h after centrifugation at 5000 × g for 10 min. The resultant precipitate was washed with 95% ethanol and water-free ethanol respectively after suction and lyophilized in vacuo. The polysaccharides content (87.4%) in extracts was determined using the phenol-sulfuric acid method. 2.3. Monosaccharide composition analysis of APS The monosaccharide was analyzed by The hydrolyzates of APS were analyzed by HPLC on an Agilent 1200 series HPLC (Agilent Tech., CA, USA) equipped with a RID, using an Hypersil NH2 column (4.6 mm × 250 mm, Dalian Elite Analytical Instrument Co. Ltd., P.R. China). The flow rate was 1 mL/min and the mobile phase was acetonitrile-water (82:18). The injection volume of mixed monosaccharide standards and AMP hydrolyzates was 10 ␮L. The temperature of column and optical unit were set at 30 ◦ C and 35 ◦ C, respectively. Quantitative determination was performed using the external standard method.

2.6. Irradiation and tissue processing Whole body IR was performed with a 60 Co radiotherapy unit. The unanesthetized mouse was restrained in a well-ventilated Perspex box and exposed to a total of 5 Gy radiation delivered at a dose rate of 1 Gy/min with a source-to-surface distance of 80 cm. All mice were euthanized by cervical dislocation at 24 h after IR. The unirradiated mice were similarly euthanized at a time equal to the IR groups. Whole liver was immediately harvested from each mouse and processed for histological and biochemical analyses. 2.7. Histological analysis Liver tissue was fixed in 4% buffered formalin, sectioned (4–5 ␮m thickness), stained with hematoxylin and eosin, and microscopically examined (IX81; Olympus Tokyo, Japan). Images were captured with a digital camera and NIS-Elements D2.30 software (Nikon, Melville, NY, USA) at original magnification of ×200. 2.8. Biochemical analysis 2.8.1. LPO assay Effect of APS treatment on IR-induced LPO activity was determined by measuring the concentrations of TBARS in the livers of the experimental and control groups, as previously described [14]. Briefly, liver homogenates were mixed with a solution of 15% Triscacodylic acid buffer (TCA), 0.375% thiobarbituric acid and 5 N HCl and incubated at 95 ◦ C for 15 min. After cooling to room temperature, the sample was centrifuged to obtain the supernatant for spectrophotometric measurement at 535 nm. 2.8.2. SOD activity assay Effect of APS treatment on IR-induced SOD activity was determined using the pyrogallol autoxidation method [15]. Briefly, liver homogenates were mixed with 62.5 mM TCA, followed by the addition of 4 mM pyrogallol as substrate. The autooxidation of pyrogallol was monitored spectrophotometrically at 420 nm.

2.4. FT-IR composition analysis of APS The APS was analyzed with FT-IR (Perkin-Elmer Spectrometer, USA) for detecting functional groups. 2.5. Experimental design All procedures involving mice were approved by the Animal Ethics Committee of the Third Military Medical University (Chongqing, China) and were carried out in accordance with the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health (Bethesda, MD, USA). The mice were acclimatized to laboratory conditions (12 h dark/light cycles, 22 ◦ C, 50% humidity) for 1 week prior to experimentation. Thirtysix male Balb/c mice (8–12 weeks old; 18–22 g) were obtained from an inbred colony maintained on-site (Center of Experimental Animals, the Third Military Medical University). Eighteen of the mice were assigned to three groups (n = 6 each) for oral APS treatment at low, mid and high doses (50, 100 or 200 mg/kg/day, respectively). Six mice were assigned to the IR group and received distilled water daily. Another six mice in the positive group were injected with amifostine (300 mg/kg body weight (bwt), intraperitoneally (i.p.)). All the mice except the blank controls received the respective treatments for seven consecutive days. At 24 h after the last treatment/control dose, the mice except the blank controls were exposed to a single dose of 5 Gy 60 Co ␥-IR (described below).

2.8.3. Catalase (CAT) activity assay Effect of APS treatment on IR-induced CAT activity was determined by measuring the CAT-mediated elimination of H2 O2 in liver tissues. Liver homogenates were mixed with 50 mM potassium phosphate buffer (pH 7.0), followed by the addition of 30 mM H2 O2 as substrate. The reaction was carried out by incubating for 10 min at 20 ◦ C. CAT enzyme activity was determined by measuring absorbance at 240 nm and calculating the decomposition of 1 ␮mol of H2 O2 per minute. 2.8.4. GST activity assay Effect of APS treatment on IR-induced GST activity was determined as previously described [16]. Liver homogenates were precipitated by mixing with 25% TCA, and glutathione (GSH) was determined by the spectrophotometric method using Ellman’s reagent. The supernatants were collected by centrifugation (3900 × g for 10 min) and mixed with 0.5 mM DTNB thiol reagent in 0.2 M phosphate buffer (pH 8.0). The GSH activity was indicated by the free endogenous sulfhydryl reacting with DTNB to form a yellow complex detectable by spectrophotometric measurement at 412 nm. 2.8.5. The enzyme activity of AST, ALT and LDH in serum The mice venous blood samples were collected into tubes without anticoagulant. Serum was separated by centrifugation after clotting and stored at −80 ◦ C until assay. The enzyme activity of

Y. Liu et al. / International Journal of Biological Macromolecules 68 (2014) 209–214

211

AST, ALT and LDH was detected by automated biochemical analyzer (HITACHI 7150, Japan). 2.9. Western blotting assay Liver tissue lysates (50 ␮g total protein from 100 mg of homogenized tissue) were separated by 12% SDS-PAGE and transferred to a polyvinylidene fluoride membrane. After blocking with 5% skim milk for 4 h and washing with Tris-buffered saline (TBS; 3 × 5 min), the membrane was incubated overnight at 4 ◦ C with rabbit anti-human NF-␬B p65 polyclonal antibody (1:200; Santa Cruz Biotechnology, Santa Cruz, CA, USA), followed by a 2 h incubation at room temperature with HRP-conjugated goat anti-rabbit IgG (1:2000; Zhongshan Golden Bridge Biotechnology Co., Beijing, China). Immunoreactive bands were detected by enhanced chemiluminescence (ECL) reagent (Pierce, Rockford, IL, USA), visualized by autoradiography, and quantified by the QuantityOne analysis system (Bio-Rad, Hercules, CA, USA). ␤-Actin served as the internal control. 2.10. Statistical analysis The data are presented as mean ± standard error of the mean (SEM). Significance of differences between the groups was assessed by one-way analysis of variance (ANOVA) with Tukey’s post hoc test. p-Values less than 0.05 were considered to indicate statistical significance.

3. Results 3.1. The monosaccharide composition and FT-IR analysis of APS Monosaccharide composition analysis of AMP was composed of 4 monosaccharides as: rhamnose, glucose, galactose, arabinose in a molar ratio of 1:18.45:3.53:7.11. FTIR was recorded on a (MODEL: Spectrum one) Perkin-Elmer spectrometer in a range from 4000 to 400 cm−1 using a KBr-pellet method. As shown in Fig. 1, the FTIR spectra of APS indicated that the absorption bands at 3410, 2927, 1751 and 1635 cm−1 were assigned to O H stretching, C H stretching and carboxyl ion stretching band (COO ), respectively. At 1000–1500 cm−1 which

Fig. 1. The FTIR analysis of APS.

referred to as finger print region, the absorption bands were due to N O, C H, C O and C N for AMP. 3.2. APS pre-treatment attenuates IR-induced injury to livers of mice Compared to the blank control group, the IR group showed typical histological features of radiation injury in liver, which included necrosis in the portal region, enlarged nuclei, cytoplasmic basophilia, some hemorrhaging, and extensive congestion in the central vein (Fig. 2B). The amifostine treatment significantly improved the radiation injury in liver with approximately normal structure (Fig. 2C). The IR groups administered APS pre-treatments showed evidence of less extensive IR-induced hepatic injury, and the protective effect appeared to be dose related. Compared to the untreated IR group, the 50 mg/kg pretreated livers showed milder venous congestion and statuses (Fig. 2D). The 100 mg/kg pre-treated livers showed widespread hyperemia in the central venous hepatic lobule region with slight expansion into the hepatic sinusoid, irregular liver cell arrangement, and milder edema and statuses (Fig. 2E). The 200 mg/kg pre-treated livers showed remarkable improvements in all of the histological features of IR-induced hepatic injury (Fig. 2F).

Fig. 2. Effects of APS pre-treatment on the IR-induced histologic changes in liver tissues of mice. Hematoxylin-eosin stained liver sections (200×) are shown from (A) blank control mice, (B) IR mice, (C) amifostine treated mice, (D) low dose APS treated IR mice, (E) mid dose APS treated IR mice, and (F) high dose APS treated IR mice.

212

Y. Liu et al. / International Journal of Biological Macromolecules 68 (2014) 209–214

Fig. 3. Effects of APS pre-treatment on IR-induced changes in hepatic NF-␬B activity. (A) Western blot data are plotted as mean (n = 6) ± SEM. Lanes: 1, blank control; 2, untreated IR; 3, Amifostine (300 mg/kg); 4, low dose APS (50 mg/kg) + IR; 5, mid dose APS (100 mg/kg) + IR; 6, high dose APS (200 mg/kg) + IR. (B) The normalized level of phosphorylated p65. **p < 0.01 vs. blank control group; # p < 0.05, ## p < 0.01 vs. IR group.

3.3. APS ameliorates IR-induced NF-ÄB activity in mice To test whether NF-␬B, a redox-sensitive transcription factor, is responsible for the increased antioxidant activities in APS pretreated liver, we measured the phosphorylation level of NF-␬B p65. Compared to the unirradiated control group, the untreated IR group showed significantly enhanced levels of NF-␬B protein

in liver tissues (Fig. 3). All groups of mice administered the APS pre-treatments showed significantly reduced levels of IR-induced hepatic NF-␬B protein expression that was significantly different from the untreated IR group (p < 0.01); furthermore, the group pretreated with high doses (200 mg/kg) of APS showed no significant differences in NF-␬B protein level compared to the blank control group (p > 0.05).

Fig. 4. Effects of APS on IR-induced changes in oxidative stress-related factors. (A) Catalase activity; (B) glutathione S-transferase activity; (C) SOD activity; (D) lipid peroxidations were measured in mice liver homogenates. Data are presented as mean (n = 6) ± SEM. *p < 0.05, **p < 0.01 vs. blank control group; # p < 0.05, ## p < 0.01 vs. IR group.

Y. Liu et al. / International Journal of Biological Macromolecules 68 (2014) 209–214

3.4. APS ameliorates IR-induced oxidative stress-related injury in mice We assessed the effect of APS pre-treatment on the antioxidant enzyme activities at 24 h after IR to investigate the mechanism of liver protection against radiation-induced damage. Compared to the unirradiated control group, the untreated IR group showed significantly increased TBARS activity but significantly decreased SOD, CAT and GSH activities. All groups of mice administered the APS pre-treatments showed significantly reduced levels of IR-induced TBARS activity and significantly increased levels of IR-suppressed SOD, CAT and GSH activities (Fig. 4). Collectively, these results suggest that the oxidative stress reaction was enhanced upon radiation exposure and that APS was capable of ameliorating the response, thereby protecting against IR-induced injury. 3.5. APS ameliorates serum marker enzymes in mice exposed to whole body irradiation The effect of ion-radiation exposure on the status of the marker enzymes in serum is presented in Fig. 5. Radiation exposure resulted in a highly significant increase in the levels of the serum marker enzymes AST, ALT (both 2- to 3-fold) and LDH (8-fold), compared to the control group. Pre-treatment with APS prevented these IR-induced elevations. These results indicate that APS could repair the IR-induced damage, agreeing with the histological findings. 4. Discussion The recent worldwide expansion of technologies based on electromagnetic radiation, from wireless communications to the

213

medical field, has benefited our lives tremendously. Yet, the potential for persistent exposure to electromagnetic radiation remains a concern. Both ionizing and non-ionizing radiation can affect the distribution of free radicals in a human system, thereby disrupting essential physiological and metabolic processes that may produce detrimental biological effect [17–19]. Under normal conditions, the human body synthesizes and utilizes many types of free radicals, the most well studied being reactive oxygen species (ROS) and nitric oxide (NO) [20]. Under stimulatory conditions, however, the amount of free radicals or their byproducts is significantly enhanced and eventually triggers the antioxidant system to help clear the accumulated molecules and protect the cell from secondary damage. NF-␬B is a major mediator of all inflammatory responses exerting its effects on inflammatory cytokines, such as tumor necrosis factor-a, interleukin-6, adhesion molecules, and various inflammatory enzymes. Moreover, NF-␬B expression was shown to be augmented by ion-irradiation in a mouse model [21]. In this study, 5 Gy of ion irradiation was shown to cause an increase in LPO level, whereas the activities of antioxidant enzymes SOD, GSH levels, and TRABS values were decreased. It is crucial to scavenge accumulated ROS because of its extremely strong oxidative capacity. ROS triggers lipid peroxidation of unsaturated fatty acids, ultimately generating the methane dicarboxylic aldehyde (MDA) that destabilizes the integrity of the cellular structure by decreasing fluidity and increasing permeability of the membrane. In addition, ROS direct attack on proteins causes denaturation or cross-linking, thereby disabling enzymatic activities and disrupting signaling pathways. Finally, ROS can directly attack DNA molecules and disrupt gene expression; for example, ROS has been shown to inhibit expression of the anti-apoptosis gene Bcl-2 [22].

Fig. 5. Effect of APS pre-treatment on serum marker enzymes in mice exposed to whole body IR. (A) ALT activity; (B) AST activity; (C) LDH activity was measured mice sera. Data are presented as mean (n = 6) ± SEM. *p < 0.05, **p < 0.01 vs. blank control group; # p < 0.05, ## p < 0.01 vs. IR group.

214

Y. Liu et al. / International Journal of Biological Macromolecules 68 (2014) 209–214

The presence of the cytosolic enzymes AST, ALT, and LDH in serum serves as a diagnostic marker of cellular damage, as they are known to leak out from damaged tissues into the bloodstream when the cell membrane ruptures or becomes permeable [23]. The serum concentration of these cellular enzymes reflects alterations in plasma membrane integrity and permeability of the tissues. In the present study, the increased activities of AST, ALT, and LDH that were observed in mouse serum was a clear indication of cellular damage caused by exposure to ion radiation. Moreover, these findings are consistent with a previous study of radiation exposure that showed significant decreases in the activities of serum markers [24]. In another study, treatment with hesperidin led to significant decreases in the activities of AST, ALT, and LDH in serum, suggesting that hesperidin offers protection by preserving the structural integrity of the membrane against radiotoxicity [25]. Despite the increased research interest in uncovering the mechanisms of IR injury, very few studies have focused on identifying novel therapeutic agents. Some natural compounds that are known to interact with the oxidative stress pathway, such as grape seed extract, may represent promising candidates for protecting against ionizing radiation [26]. In our present study, amifostine was used as a positive control to evaluate radioprotective activity of Astragalus polysaccharide. Amifostine is a Food and Drug Administration approved radioprotector used in clinical and is considered as “gold standard”, which functions via free radical scavenging mechanism. The side effect associated with amifostine as hypotension, vomiting and limits its clinical usage. Polysaccharides are biological response modifiers and cause no harm and additional stress on the body. In this study of APS’s potential beneficial effects against IR injury in mice, we first established that ionizing radiation induces the oxidative stress mechanism, which in turn causes damage in the liver tissue, likely through its effects on the activity and content of SOD, CAT, GSH, and TBARS. APS pre-treatment for seven consecutive days significantly benefited the injury status of these mice, specifically by mitigating uncontrolled ROS products by increasing SOD activity, CAT activity, and GSH level, and by decreasing lipid peroxidation. These results agree with a previous study of APS, which showed that this active constituent of Astragalus membranaceus could increase GSH-Px activity and SOD activity, and decrease MDA in sera [27,28]. 5. Conclusions In conclusion, APS provides protective effects against IRinduced injury in liver of mice when administered as a continuous pre-treatment regimen, especially when given at a high dose (200 mg/kg). To the best of our knowledge, this is the first investigation of a plant-derived polysaccharide in an ion radiation animal model system. The results also validate the idea that studies of this traditional Chinese medicine should be continued to further explore its potential as a prophylactic or therapeutic treatment

of ionizing radiation-induced oxidative stress injury. Ultimately APS may be useful as the supplement for patients who undergo radiotherapy, but this possibility needs further experimental investigation. Competing interest No competing financial interests exist for any of the authors. Acknowledgments This work was supported by grants from CWS11J132 and National Natural Science Foundation of China (NSFC 81001441). References [1] A. Agrawal, D. Chandra, R.K. Kale, Mol. Cell. Biochem. 224 (2001) 9–17. [2] T.K. Hei, H. Zhou, Y. Chai, B. Ponnaiya, V.N. Ivanov, Curr. Mol. Pharmacol. 4 (2011) 96–105. [3] S. De, T.P. Devasagayam, Free Radic. Res. 45 (2011) 1342–1353. [4] D.R. Spitz, E.I. Azzam, J.J. Li, D. Gius, Cancer Metastasis Rev. 23 (2004) 311–322. [5] J.F. Weiss, M.R. Landauer, Ann. N.Y. Acad. Sci. 899 (2000) 44–60. [6] H.C. Goel, J. Prasad, S. Singh, R.K. Sagar, I.P. Kumar, A.K. Sinha, Phytomedicine 9 (2002) 15–25. [7] R. Arora, D. Gupta, R. Chawla, R. Sagar, A. Sharma, R. Kumar, J. Prasad, S. Singh, N. Samanta, R.K. Sharma, Phytother. Res. 19 (2005) 1–22. [8] M. Sinha, D.K. Das, K. Manna, S. Datta, T. Ray, A.K. Sil, S. Dey, Free Radic. Res. 46 (2012) 842–849. [9] X. Wang, S. Wang, Y. Li, F. Wang, X. Yang, J. Yao, Int. J. Biol. Macromol. 60 (2013) 248–252. [10] J. Lu, X. Chen, Y. Zhang, J. Xu, L. Zhang, Z. Li, W. Liu, J. Ouyang, S. Han, X. He, Int. J. Mol. Med. 31 (2013) 1463–1470. [11] X. Du, B. Zhao, J. Li, X. Cao, M. Diao, H. Feng, X. Chen, Z. Chen, X. Zeng, Int. Immunopharmacol. 14 (2012) 463–470. [12] W.M. Huang, Y.Q. Liang, L.J. Tang, Y. Ding, X.H. Wang, Exp. Ther. Med. 6 (2013) 199–203. [13] X.T. Li, Y.K. Zhang, H.X. Kuang, F.X. Jin, D.W. Liu, M.B. Gao, Z. Liu, X.J. Xin, Int. J. Mol. Sci. 13 (2012) 1747–1761. [14] J.A. Buege, S.D. Aust, Methods Enzymol. 52 (1978) 302–310. [15] S. Marklund, G. Marklund, Eur. J. Biochem. 47 (1974) 469–474. [16] I.F. Benzie, J.J. Strain, Anal. Biochem. 239 (1996) 70–76. [17] S.C. White, S.M. Mallya, Aust. Dent. J. 57 (Suppl. 1) (2012) 2–8. [18] P.R. Lawler, J. Afilalo, M.J. Eisenberg, L. Pilote, Am. J. Cardiol. 109 (2012) 31–35. [19] A. Sannino, O. Zeni, S. Romeo, R. Massa, G. Gialanella, G. Grossi, L. Manti, Vijayalaxmi, M.R. Scarfi, J. Radiat. Res. (2013). [20] M.L. Circu, T.Y. Aw, Free Radic. Biol. Med. 48 (2010) 749–762. [21] N. Li, M. Karin, Proc. Natl. Acad. Sci. U. S. A. 95 (1998) 13012–13017. [22] D.A. Hildeman, T. Mitchell, B. Aronow, S. Wojciechowski, J. Kappler, P. Marrack, Proc. Natl. Acad. Sci. U. S. A. 100 (2003) 15035–15040. [23] K.H. Sabeena Farvin, R. Anandan, S.H. Kumar, K.S. Shiny, T.V. Sankar, T.K. Thankappan, Pharmacol. Res. 50 (2004) 231–236. [24] L.A. Ramadan, H.M. Roushdy, G.M. Abu Senna, N.E. Amin, O.A. El-Deshw, Pharmacol. Res. 45 (2002) 447–454. [25] K.B. Kalpana, N. Devipriya, M. Srinivasan, V.P. Menon, Mutat. Res. 676 (2009) 54–61. [26] H.N. Saada, U.Z. Said, N.H. Meky, A.S. Abd El Azime, Phytother. Res. 23 (2009) 434–438. [27] Z.Q. Hei, H.Q. Huang, J.J. Zhang, B.X. Chen, X.Y. Li, World J. Gastroenterol. 11 (2005) 4986–4991. [28] W.Y. Sun, W. Wei, L. Wu, S.Y. Gui, H. Wang, J. Ethnopharmacol. 112 (2007) 514–523.

Astragalus polysaccharide ameliorates ionizing radiation-induced oxidative stress in mice.

Radioprotective compounds from plant resources may represent safe and cost-effective prophylactic and therapeutic agents. This study was designed to i...
2MB Sizes 0 Downloads 5 Views