Radiation-induced Lipid Peroxidation Research Articles

Investigations of antioxidant-mediated protection and mitigation of radiation-induced DNA damage and lipid peroxidation in murine skin

Purpose: Radioprotection and mitigation effects of the antioxidants, Eukarion (EUK)-207, curcumin, and the curcumin analogs D12 and D68, on radiation-induced DNA damage or lipid peroxidation in murine skin were investigated. These antioxidants were studied because they have been previously reported to protect or mitigate against radiation-induced skin reactions.Methods: DNA damage was assessed using two different assays. A cytokinesis-blocked micronucleus (MN) assay was performed on primary skin fibroblasts harvested from the skin of C3H/HeJ male mice 1 day, 1 week and 4 weeks after 5 Gy or 10 Gy irradiation. Local skin or whole body irradiation (100 kVp X-rays or caesium (Cs)-137 γ-rays respectively) was performed. DNA damage was further quantified in keratinocytes by immunofluorescence staining of γ-histone 2AX (γ-H2AX) foci in formalin-fixed skin harvested 1 hour or 1 day post-whole body irradiation. Radiation-induced lipid peroxidation in the skin was investigated at the same time points as the MN assay by measuring malondialdehyde (MDA) with a Thiobarbituric acid reactive substances (TBARS) assay.Results: None of the studied antioxidants showed significant mitigation of skin DNA damage induced by local irradiation. However, when EUK-207 or curcumin were delivered before irradiation they provided some protection against DNA damage. In contrast, all the studied antioxidants demonstrated significant mitigating and protecting effects on radiation-induced lipid peroxidation at one or more of the three time points after local skin irradiation.Conclusion: Our results show no evidence for mitigation of DNA damage by the antioxidants studied in contrast to mitigation of lipid peroxidation. Since these agents have been reported to mitigate skin reactions following irradiation, the data suggest that changes in lipid peroxidation levels in skin may reflect developing skin reactions better than residual post-irradiation DNA damage in skin cells. Further direct comparison studies are required to confirm this inference from the data.

Ferulic acid, a dietary phenolic acid, modulates radiation effects in Swiss albino mice

The radioprotective efficacy of Ferulic acid (FA) against whole body gamma radiation was studied in Swiss albino mice. To study the radiation protection, mice were administered with ferulic acid intraperitoneally (i.p) (50mg/kg body weight.), once daily for five consecutive days. One hour after the last administration of ferulic acid on the sixth day, animals were whole body exposed to 8Gy gamma radiations. Effect of ferulic acid pretreatment on radiation-induced changes in antioxidant enzymes and lipid peroxidation status in spleen, liver and intestine was analyzed. A significant increase in the antioxidant enzymatic status and decreased lipid peroxidation marker levels were observed in ferulic acid pretreated group, when compared to the irradiated animals. Our study also shows increased % tail DNA, tail length, tail moment and Olive tail moment in irradiated mice blood lymphocytes. Ferulic acid (50mg/kg body weight) pretreatment significantly decreased the % tail DNA, tail length, tail moment and Olive tail moment in irradiated mice lymphocytes. The histological observations indicated a decline in the villus height and crypt number with an increase in goblet and dead cell population in the irradiated group, which was normalized by ferulic acid pretreatment. In conclusion, present study indicated ferulic acid treatment prevents radiation-induced lipid peroxidation, DNA damage and restored antioxidant status and histopathological changes in experimental animals.

Umbelliferone protects whole-body irradiated Swiss albino mice: Study on animal survival, tissue antioxidant status and DNA damage

Protection against whole-body γ-irradiation (WBI) of Swiss albino mice intraperitonally injected with umbelliferone (UMB), in terms of mortality of irradiated animals, DNA damage and antioxidant status in liver and intestine (jejunum) has been investigated. Swiss albino mice were administered UMB (30mg/kg b.wt.), once daily for 5 consecutive days and 1 hour after the last administration of UMB on the sixth day, animals were exposed to whole-body irradiation (10Gy). Radiation-induced augmentation of lipid peroxidation (TBARS) was significantly ameliorated by UMB pretreatment. The present findings showed that radiation-induced depletion of reduced glutathione (GSH) level as well as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were significantly prevented by UMB administration. Further, it has been found that DNA damage was increased in the blood lymphocytes of WBI mice. UMB (30mg/kg b.wt.) pretreatment significantly prevented radiation-induced DNA damage in irradiated mice lymphocytes. Moreover, UMB pretreatment elevated the radiation LD50 from 8.4 to 9.5 having dose-modifying factor of 1.03. Irradiated mice showed distortion of villus anatomy with evidence of cryptitis in jejunum sections and hepatocyte degeneration in liver sections. Administration of UMB before radiation exposure prevented crypt cells damage and hepatocyte degeneration. Thus, UMB pretreatment prevented radiation-induced lipid peroxidation, DNA damage, restored tissue antioxidant status and histopathological changes in Swiss albino mice.

Effects of lazaroid U-74389G liposomes in a glioblastoma mouse model.

2098 Background: Lazaroid U-74389G (LAZ) is a 21-aminosteroid that has radioprotective effects against radiation-induced lipid peroxidation. Also in vitro antiproliferative effects have been reported against glioblastoma cell lines. The aim of this study was to use a liposomal formulation to evaluate LAZ radioprotective and antiproliferative effects in a glioblastoma mouse model. Methods: LAZ PEGylated liposomes (Lipo G) were developed at the University of Houston, College of Pharmacy. Glioblastoma cell line U87-expressing firefly luciferase reporter gene (100,000 cells in 2 μL) was injected intracranially in each male SCID hairless outbred mouse. There were 4 treatment groups (n=8-9, each): brain model (M) without treatment (control), radiation 2Gy weekly (M+R), Lipo G at 5 mg/kg dose IP twice per week (M+L) and radiation with Lipo G (M+R+L). Treatment lasted three weeks. Tumor size was monitored using non-invasive bioluminescence imaging (BLI), in each mouse. Mice were sacrificed after 3 weeks. Brain was harvested for immunohistochemistry examinations. Lipid peroxidation of brain tissues was quantified by measuring malondialdehyde (MDA) as a surrogate biomarker. Survival was evaluated using Kaplan Meier analysis at P= 0.05. Results: The relative BLI intensity was 4002.03±1737.67, 2034±737.72, 1387.36±684.53 and 2498.89±2521.32 % for M, M+R, M+L and M+R+L, respectively. The tumor size of the M+L group was reduced by 65% compared to control . For the radiation treated groups (M+R and M+R+L), there was no significant difference in tumor size compared to control group. MDA brain concentration in M+L and M+R+L groups was significantly less than in M+R group (8.27±0.78 and 10.37±3.30 µM/gm vs. 23.09± 3.79 µM/gm). The survival mean was 22.67, 25.33, 25.22 and 27.13 days for M, M+R, M+R+L and M+L groups, respectively. Mean survival of LAZ treated groups (M+L and M+R+L) was significantly longer than that of the control group Conclusions: LAZ liposomal formulations administered at 5 mg/kg dose reduced tumor growth by 65%. LAZ also protected brain tissue from radiation-induced lipid peroxidation by reducing MDA concentration by 50%. These provocative data warrant further investigation of LAZ as a radiation protectant and chemotherapeutic agent.

Radio-modulatory effects of Green Tea Catechin EGCG on pBR322 plasmid DNA and murine splenocytes against gamma-radiation induced damage

Green tea is rich in polyphenols, like catechins, which are thought to contribute to the health benefits of tea. The aim of this study was to evaluate the radioprotective effect of EGCG (epigallocatechin-3-gallate), a green tea catechin on γ-radiation induced cell damage. Under acellular condition of radiation exposure, pBR322 plasmid DNA was protected by EGCG in a concentration dependent manner. Treatment of murine splenocytes with EGCG 2h prior to radiation (3Gy), protected the cellular DNA against radiation-induced strand breaks. EGCG also inhibited γ-radiation induced cell death in splenocytes. EGCG pretreatment to the cells decreased the radiation induced lipid peroxidation and membrane damage. The levels of phase II enzymes, glutathione and lactate dehydrogenase were restored with EGCG treatment prior to radiation. Our results show that pretreatment with EGCG offers protection to pBR322 DNA under acellular condition and normal splenocytes under cellular condition, against γ-radiation induced damage and is better radioprotector in comparison to quercetin and vitamin C.

Amifostine, a radioprotectant agent, protects rat brain tissue lipids against ionizing radiation induced damage: An FTIR microspectroscopic imaging study

Amifostine is the only approved radioprotective agent by FDA for reducing the damaging effects of radiation on healthy tissues. In this study, the protective effect of amifostine against the damaging effects of ionizing radiation on the white matter (WM) and grey matter (GM) regions of the rat brain were investigated at molecular level. Sprague–Dawley rats, which were administered amifostine or not, were whole-body irradiated at a single dose of 800cGy, decapitated after 24h and the brain tissues of these rats were analyzed using Fourier transform infrared microspectroscopy (FTIRM). The results revealed that the total lipid content and CH2 groups of lipids decreased significantly and the carbonyl esters, olefinicCH and CH3 groups of lipids increased significantly in the WM and GM after exposure to ionizing radiation, which could be interpreted as a result of lipid peroxidation. These changes were more prominent in the WM of the brain. The administration of amifostine before ionizing radiation inhibited the radiation-induced lipid peroxidation in the brain. In addition, this study indicated that FTIRM provides a novel approach for monitoring ionizing radiation induced-lipid peroxidation and obtaining different molecular ratio images can be used as biomarkers to detect lipid peroxidation in biological systems.

Abstract 5460: Dual efficacy of Lazaroid U-74389G liposomes in glioblastoma mouse model

Abstract Purpose: Lazaroid U-74389G (LAZ) is a 21-aminosteroid that has radioprotective effect against radiation-induced lipid peroxidation. In-vitro antiproliferative effect was reported against Glioblastoma primary cell lines. The aim of this study was to use a liposomal formulation in a proof-of-concept efficacy study to evaluate LAZ radioprotective and antiproliferative effects in Glioblastoma mouse model. Methods: LAZ PEGylated liposomes (Lipo G) were developed in our laboratory. Lipo G size was 80-90 nm with Zeta potential of -22mv. Glioblastoma cell line U87-Lexpressing firefly luciferase reporter gene (100,000 cells in 2 μL) was injected intracranially in each male SCID hairless outbred mouse. The mice were randomized among 4 treatment groups (n=8-9, each): brain model (M) without treatment (control), radiation of 2Gy once a week (M+R), Lipo G at 5 mg/kg dose IP twice a week (M+L) and radiation with Lipo G (M+R+L). The treatment lasted three weeks. The tumor size was monitored using non-invasive bioluminescence imaging (BLI), in each mouse, expressed as the relative BLI photon intensity on the second and third week to that of the first measurement. The mice were sacrificed at the end of the third week and the whole brain was harvested for immunohistochemistry examinations. Lipid peroxidation of brain tissues was quantified by measuring malondialdehyde (MDA) as a surrogate biomarker. The survival was evaluated using Kaplan Meier analysis at P = 0.05. Results: The relative BLI intensity was 4002.03±1737.67, 2034±737.72, 1387.36±684.53 and 2498.89±2521.32 % for M, M+R, M+L and M+R+L, respectively. The tumor size of the M+L group was reduced by 65% compared to the control group. For the radiation treated groups (M+R and M+R+L), there was no significant difference in the tumor size suppression compared to the control group. MDA brain concentration in M+L and M+R+L groups was significantly less than that in M+R group (8.27±0.78 and 10.37±3.30 µM/gm vs. 23.09± 3.79 µM/gm). The survival mean was 22.67, 25.33, 25.22 and 27.13 days for M, M+R, M+R+L and M+L groups, respectively. The mean survival duration of LAZ treated groups (M+L and M+R+L) was significantly longer than that of the control group (27.13 and 25.22 day vs. 22.67 day, respectively). Conclusion: LAZ liposomal formulations administered at 5 mg/kg dose delivered a therapeutic concentration of LAZ to the brain for the efficacy of suppressing Glioblastoma tumor growth (65% reduction). The liposomal LAZ also protected the brain tissue from radiation-induced lipid peroxidation by reducing MDA concentration (lipid peroxidation surrogate) to 50%. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5460. doi:10.1158/1538-7445.AM2011-5460

Protective Role of Tea Polyphenols in Combination against Radiation‐induced Haematopoietic and Biochemical Alterations in Mice

The purpose of this study was to investigate the radioprotective effects of tea polyphenols (TPs) in various combinations against radiation-induced damage in mice. Mice were divided into different groups: non-irradiated control, irradiated control, amifostine (43.6 mg/kg, i.v. 30 min before irradiation; positive control) and various combinations of tea polyphenols in different doses. The radioprotective effect on the haematopoietic system, serum cytokines and endogenous antioxidant enzymes were studied. TP50, containing approximately 50% of (-)-epigallochatechin-3-gallate in addition to other catechins, showed the greatest radioprotective effect against radiation-induced changes in haematological parameters (red blood cell count, white blood cell count and haemoglobin), and maintained the spleen and thymus indices unchanged (spleen or thymus weight/body weight × 1000). Tea polyphenols also significantly decreased radiation-induced lipid peroxidation (malondialdehyde levels), elevated endogenous antioxidant enzymes (superoxide dismutase) and reduced the serum cytokines which were elevated in radiation-induced toxicity. This evidence shows the potential of tea polyphenols, particularly in the combination found in TP50, as radioprotectors in mice, especially regarding recovery of the haematopoietic system, antioxidant potential activity and reduction of inflammatory cytokines.

Protection of Cellular DNA and Membrane from γ-Radiation–Induced Damages and Enhancement in DNA Repair by Sesamol

Sesamol (SM), a nutritional phenolic antioxidant compound present in sesame seeds, protected pBR 322 DNA from gamma radiation-induced damages. SM prevented gamma radiation-induced degradation of covalently closed circular form of plasmid DNA in a concentration-dependent manner. Also SM protected cellular DNA of mouse blood leukocytes exposed to 4 Gy gamma radiation, ex vivo, as revealed by the data from alkaline comet assay studies. SM (5 mM) showed a faster time-dependant decrease of the radiation-induced DNA damage in mouse blood leukocytes following postirradiation incubation ex vivo, which could be attributed to enhanced DNA repair. SM protected the biomembranes from radiation-induced lipid peroxidation. Thus, SM could act as a radioprotector for the biomembranes and cellular DNA against the deleterious effects of ionizing radiation.

Morin (2′,3,4′,5,7-Pentahydroxyflavone) Protected Cells against γ-Radiation-Induced Oxidative Stress

Ionizing radiation can induce cell damage by generating reactive oxygen species (ROS). The present study was carried out to investigate the radio-protective effects of a flavonoid compound, morin (2',3,4',5,7-pentahydroxyflavone) and the underlying mechanisms. Morin was found to reduce the intracellular ROS generated by γ-irradiation. Moreover, morin protected cellular components against radiation-induced membrane lipid peroxidation and cellular DNA damage, which are the main targets of radiation-induced cell damage. Morin recovered cell viability damaged by radiation via inhibition of apoptosis. Irradiated cells with morin treatment reduced Bax, phospho Bcl-2, active caspase 9 and caspase 3, which were induced by γ-radiation. Irradiated cells with morin recovered the expression of Bcl-2 reduced by γ-radiation. Morin exerted anti-apoptotic effects via inhibition of mitogen-activated protein kinase kinase-4 (MKK4/SEK1)-c-Jun NH(2) -terminal kinase (JNK)-activator protein 1 (AP-1) cascades induced by γ-radiation. The results suggest that morin protects cells against oxidative stress induced by radiation via reduction of ROS and attenuation of SEK1-JNK-AP-1 pathway.

Protection of DNA and membranes from gamma-radiation induced damages by Centella asiatica

Abstract Objectives The objective of the present study was to examine the ability of Centella asiatica extract to offer protection to DNA and membranes against the deleterious effects of ionizing radiation exposure. Methods Protection of DNA under in-vitro conditions of irradiation was estimated using plasmid relaxation assay. For in-vivo studies the extract was administered orally to mice exposed to whole-body γ-radiation. The ability of the extract to offer protection against whole-body γ-radiation exposure was analysed by performing an alkaline comet assay on mouse bone marrow cells. The extent of lipid peroxidation was estimated using the TBARS (thio-barbituric acid reacting substances) method, in order to monitor membrane damage. Radiation-induced mortality of the animals following a lethal dose of γ-radiation was also examined. Key findings Centella asiatica extract significantly reduced radiation-induced damage to DNA. The extent of radiation-induced mortality and lipid peroxidation was also found to be considerably reduced in animals administered with the extract. Conclusions Centella asiatica rendered radioprotection to DNA and membranes against radiation exposure, both in vitro and in vivo. We have earlier reported that administration of the extract can prevent a radiation-induced decline in antioxidant enzyme levels. This suggests that radioprotection by Centella asiatica extract could be mediated by mechanisms that act in a synergistic manner, especially involving antioxidant activity.

Modulation of Ionizing Radiation Induced Oxidative Imbalance by Semi-Fractionated Extract ofPiper betle: An In Vitro and In Vivo Assessment

The study was planned to evaluate modulatory effect of aqueous extract of Piper betle leaf (PBL) on ionizing radiation mediated oxidative stress leading to normal tissues damage during radiotherapy and other radiation exposures. The total polyphenols and flavonoids known as free radical scavenger (chelators) were measured in the extract. To ascertain antioxidant potential of PBL extract we studied free radical scavenging, metal chelation, reducing power, lipid peroxidation inhibition and ferric reducing antioxidant properties (FRAP) using in vitro assays. Mice were exposed to varied radiation doses administered with the same extract prior to irradiation to confirm its oxidative stress minimizing efficacy by evaluating ferric reducing ability of plasma, reduced glutathione, lipid peroxidation and micro-nuclei frequency. PBL extract was effective in scavenging DPPH (up to 92% at 100 microg/ml) and superoxide radicals (up to 95% at 80 microg/ml), chelated metal ions (up to 83% at 50 microg/ml) and inhibited lipid peroxidation (up to 55.65% at 500 microg/ml) in a dose dependant manner using in vitro model. Oral administration of PBL extract (225 mg/kg body weight) 1 hr before irradiation in mice significantly enhanced (p < 0.01) radiation abated antioxidant potential of plasma and GSH level in all the observed organs. The treatment with extract effectively lowered the radiation induced lipid peroxidation at 24 hrs in all the selected organs with maximum inhibition in thymus (p < 0.01). After 48 hrs, lipid peroxidation was maximally inhibited in the group treated with the extract. Frequency of radiation induced micronucleated cells declined significantly (34.78%, p < 0.01) at 24 hrs post-irradiation interval by PBL extract administration. The results suggest that PBL extract has high antioxidant potential and relatively non-toxic and thus could be assertively used to mitigate radiotherapy inflicted normal tissues damage and also injuries caused by moderate doses of radiation during unplanned exposures.

In vivo radioprotection studies of 3,3′-diselenodipropionic acid, a selenocystine derivative

3,3′-Diselenodipropionic acid (DSePA), a diselenide and a derivative of selenocystine, was evaluated for in vivo radioprotective effects in Swiss albino mice, at an intraperitoneal dose of 2 mg/kg body wt, for 5 days before whole-body exposure to γ-radiation. The radioprotective efficacy was evaluated by assessing protection of the hepatic tissue, the spleen, and the gastrointestinal (GI) tract and survival against sub- and supralethal doses of γ-radiation. DSePA inhibited radiation-induced hepatic lipid peroxidation, protein carbonylation, loss of hepatic function, and damage to the hepatic architecture. DSePA also attenuated the depletion of endogenous antioxidants such as glutathione, glutathione peroxidase, superoxide dismutase, and catalase in the livers of irradiated mice. DSePA also restored the radiation-induced reduction in villus height, crypt cell numbers, and spleen cellularity, indicating protective effects on the GI tract and the hematopoietic system. The results from single-cell gel electrophoresis of the peripheral blood leukocytes showed that DSePA can attenuate radiation-induced DNA damage. The mRNA expression analysis of genes revealed that DSePA augmented GADD45α and inhibited p21 in both spleen and liver tissues. DSePA also inhibited radiation-induced apoptosis in the spleen and reversed radiation-induced alterations in the expression of the proapoptotic BAX and the antiapoptotic Bcl-2 genes. In line with these observations, DSePA improved the 30-day survival of irradiated mice by 35.3%. In conclusion, these findings clearly confirm that DSePA exhibits protective effects against whole-body γ-radiation and the probable mechanisms of action involve the maintenance of antioxidant enzymes, prophylactic action through the attenuation of the DNA damage, and inhibition of apoptosis.

Protection of DNA and membranes from gamma-radiation induced damages by &lt;I&gt;Centella asiatica&lt;/I&gt;

The objective of the present study was to examine the ability of Centella asiatica extract to offer protection to DNA and membranes against the deleterious effects of ionizing radiation exposure. Protection of DNA under in-vitro conditions of irradiation was estimated using plasmid relaxation assay. For in-vivo studies the extract was administered orally to mice exposed to whole-body gamma-radiation. The ability of the extract to offer protection against whole-body gamma-radiation exposure was analysed by performing an alkaline comet assay on mouse bone marrow cells. The extent of lipid peroxidation was estimated using the TBARS (thio-barbituric acid reacting substances) method, in order to monitor membrane damage. Radiation-induced mortality of the animals following a lethal dose of gamma-radiation was also examined. Centella asiatica extract significantly reduced radiation-induced damage to DNA. The extent of radiation-induced mortality and lipid peroxidation was also found to be considerably reduced in animals administered with the extract. Centella asiatica rendered radioprotection to DNA and membranes against radiation exposure, both in vitro and in vivo. We have earlier reported that administration of the extract can prevent a radiation-induced decline in antioxidant enzyme levels. This suggests that radioprotection by Centella asiatica extract could be mediated by mechanisms that act in a synergistic manner, especially involving antioxidant activity.

Radiation-induced lipid peroxidation activates src kinase and triggers nuclear EGFR transport

Purpose Elucidation of the molecular mechanism of radiation-induced activation of src kinase, which initiates EGFR internalization and nuclear transport. Material and methods Radiation-induced src activation was investigated in the bronchial carcinoma cell line A549. Proteins were Western blotted and quantified by the help of specific antibodies. Residual DNA-damage was quantified with γH 2AX-foci analysis. Radiation-induced lipid peroxidation was prevented by acetyl-cysteine. Results The radiation-induced src activation and EGFR stabilization could be mimicked by addition of hydroxy-nonenal (HNE), one of the major lipid peroxidation products. Radiation-generated HNE is bound to EGFR and src and correlated with complex formation between both following radiation. Treatment with HNE activated src and stimulated radiation-associated EGFR and caveolin 1 phosphorylations resulting in increased nuclear transport of EGFR. Consequently, radiation-induced phosphorylation and activation of DNA-PK were increased. This phosphorylation was associated with improved removal of residual damage 24 h after irradiation. Inhibition of radiation-induced HNE generation by acetyl-cysteine blocked radiation-induced src activation and EGFR phosphorylation. Conclusions HNE generated in response to radiation exposure activates src kinase and is involved in regulation of radiation-stimulated DNA-repair processes.

Investigations on the antioxidant activity of 5,8-dihydroxy-1,4-dihydro-1,4-methanonaphthalene (DDMN)

5,8-dihydroxy-1,4-dihydro-1,4-methanonaphthalene (DDMN), a substituted phenol, is synthesized by the reduction of a cyclic dione, 1,4,4a,8a-tetrahydro-endo-1,4-methano-naphtha-5,8-dione (THMND). The pulse radiolysis technique has been employed to understand the nature of transient species formed by the reaction of radiolytic species of water radiolysis with DDMN. •OH radicals were observed to react with DDMN with a bimolecular rate constant of 1.5 × 1010 dm3 mol−1 s−1. The inhibition of radiation-induced lipid-peroxidation by DDMN was studied in rat liver microsomes by assessing the formation of thiobarbituric acid reactive substances (TBARS). It was found to be strongly inhibitory. The results suggest that DDMN has very good antioxidant activity and may possibly emerge as a good radio-protector.

Effect of ursolic acid, a triterpenoid antioxidant, on ultraviolet-B radiation-induced cytotoxicity, lipid peroxidation and DNA damage in human lymphocytes

Exposure to ultraviolet B (UVB, 280–320) radiation induces the formation of reactive oxygen species (ROS) in the biological system. In this study, we examined the protective effect of ursolic acid on UVB-induced lipid peroxidation and oxidative DNA damage with reference to alterations in cellular antioxidant status in human lymphocytes. Series of in vitro tests (hydroxyl radical, superoxide, nitric oxide, DPPH and ABTS radical scavenging assays) demonstrates antioxidant property of ursolic acid in our study. Treatment of lymphocytes with ursolic acid alone (at 10 μg/mL) gave no significant change in cell viability, thiobarbituric acid reactive substances (TBARSs), lipid hydroperoxides (LHPs), % tail DNA and tail moment when compared with normal lymphocytes. UVB-exposure significantly increased TBARS, LHP and % tail DNA, tail moment; decreased % cell viability and antioxidant status in irradiated lymphocytes. Treatment with ursolic acid 30 min prior to UVB-exposure resulted in a significant decline of TBARS, LHP, % tail DNA and tail moment and increased % cell viability as ursolic acid concentration increased. Based on our results we conclude that ursolic acid, a dietary antioxidant, mediates its protective effect through modulation of UVB-induced reactive oxygen species.

Delayed activation of PKCδ and NFκB and higher radioprotection in splenic lymphocytes by copper (II)–Curcumin (1:1) complex as compared to curcumin

A mononuclear 1:1 copper complex of curcumin had been found to be superior to curcumin in its anti-oxidant properties. This paper describes the radio-protective effects of the complex in splenic lymphocytes from swiss mice. The complex was found to be very effective in protecting the cells against radiation-induced suppression of glutathione peroxidase, catalase and superoxide dismutase (SOD) activities. Both curcumin and the complex protected radiation-induced protein carbonylation and lipid peroxidation in lymphocytes with the complex showing better protection than curcumin. It also showed better overall protection by decreasing the radiation-induced apoptosis. The kinetics of activation of PKCdelta and NFkappaB after irradiation in presence or absence of these compounds was looked at to identify the molecular mechanism involved. The modulation of irradiation-induced activation of PKCdelta and NFkappaB by curcumin and the complex was found different at later time periods although the initial response was similar. The early responses could be mere stress responses and the activation of crucial signaling factors at later time periods may be the determinants of the fate of the cell. In this study this delayed effect was observed in case of complex but not in case of curcumin. The delayed effect of the complex along with the fact that it is a better free radical scavenger must be the reason for its better efficacy. The complex was also found to be less cytotoxic then curcumin at similar concentration.

Quantification of the water/lipid affinity of melatonin and a pinoline derivative in lipid models

This study assessed the location of melatonin (N-acetyl-5-methoxytryptamine) and of a pinoline derivative (GWC22) [6-ethyl-1-(3-methoxyphenyl)-2-propyl-1,2,3,4-tetrahydro-beta-carboline], when present in lipid assemblies such as linoleate micelles, phosphatidylcholine liposomes or low density lipoproteins (LDL). The efficiency of radical scavenging by these compounds is highly dependent on their partitioning between the lipidic and aqueous phases. We determined the proportion of melatonin or GWC22 in the aqueous and lipid phases of each system (concentrations of the antioxidants ranging between 3 x 10(-5) and 10(-4) m) by assaying melatonin or GWC22 by HPLC/UV detection, or by fluorescence for melatonin in micelles. Our results show that melatonin and GWC22 were preferentially located in the aqueous phase of micelles (68.4% and 59.0%, respectively), whereas only 30.5% of melatonin and 39.0% of GWC22 were found in the lipid phase. By contrast, in phosphatidylcholine liposomes, both compounds were essentially present in the lipid phase (73.5% for melatonin and 79.1% for GWC22, versus 25.9% and 19.5% in the aqueous phase, respectively). In the case of LDL, 99.9% of the melatonin added was found in the methanol/water extracting phase containing phospholipids, unesterified cholesterol and apolipoprotein B100. The partitioning of melatonin and GWC22 in linoleate micelles gave new insights on the marked protective effect of GWC22 towards radiation-induced lipid peroxidation and allowed us to determine more accurately the lower limit values of the reaction rate constants of the two molecules studied with lipid peroxyl radicals, i.e. k(LOO.+melatonin)) >or= 9.0 x 10(4)m(-1)s(-1) and k(LOO.+GWC22) >or= 3.5 x 10(5)m(-1)s(-1).

Scoparone Inhibits Ultraviolet Radiation-Induced Lipid Peroxidation

Antioxidant capabilities of scoparone, the component of Artemisia scoparia and other medicinal plants, against lipid peroxidation induced by ultraviolet radiation or Fenton reaction have been analyzed. Lipid peroxidation was monitored by measuring the absorption spectra of the conjugated dienes and quantified by the Klein oxidation index. Obtained results imply that scoparone is a very efficient inhibitor of ultraviolet radiation-induced lipid peroxidation and damage.