Effect of N-acetylcysteine on lipopolysaccharide-induced intra-uterine fetal death and intra-uterine growth retardation in mice.

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including embryonic resorption, intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR), and preterm delivery. Reactive oxygen species (ROS) have been associated with LPS-induced developmental toxicity. N-acetylcysteine (NAC) is a glutathione (GSH) precursor and direct antioxidant. The present study investigated the effects of NAC on LPS-induced IUFD and IUGR. All pregnant mice except controls were injected with LPS (75 microg/kg, ip) on gestational day (GD) 15-17. NAC was administered in two different modes. In mode A, the pregnant mice were pretreated with two doses of NAC (either 50 plus 25 mg/kg or 200 plus 100 mg/kg) before LPS, one (either 50 or 200 mg/kg) at 12 h before LPS and the other (either 25 or 100 mg/kg) at 15 min before LPS. In mode B, the pregnant mice were administered with two doses of NAC (either 50 plus 25 mg/kg or 200 plus 100 mg/kg) in 24 h, one (either 50 or 200 mg/kg) injected immediately after LPS and the other (either 25 or 100 mg/kg) injected 3 h after LPS. The number of live fetuses, dead fetuses and resorption sites was counted on GD 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were measured and skeletal development was evaluated. Results showed that pretreatment with NAC significantly alleviated LPS-induced fetal mortality and reversed LPS-induced growth and skeletal development retardation. Correspondingly, pretreatment with NAC significantly attenuated LPS-induced elevation in TNF-alpha concentration in maternal serum and amniotic fluid and lipid peroxidation in maternal and fetal livers. By contrast to pretreatment, posttreatment with NAC had no effect on LPS-induced TNF-alpha production and lipid peroxidation. When administered after LPS, NAC did not protect against LPS-induced IUFD and IUGR and in fact aggravated LPS-induced preterm labor. All these results indicate that NAC had a dual effect on LPS-induced IUFD and IUGR. Pretreatment with NAC improves fetal survival and reverses LPS-induced fetal growth and skeletal development retardation, whereas posttreatment with NAC aggravates LPS-induced preterm labor.     

N-乙酰半胱氨酸在脂多糖诱发的胚胎损害中的双向作用

目的研究N-乙酰半胱氨酸(NAC)预处理和后处理对细菌脂多糖(LPS)引起宫内胎鼠死亡(IUFD)和生长发育迟缓(IUGR)的影响。方法实验1:LPS组小鼠于妊娠d15～17经腹腔注射LPS(75μg·kg-1),LPS+NAC组在LPS处理前和(或)处理后经腹腔注射给予NAC。所有孕鼠于妊娠d18处死。实验2:LPS组小鼠于妊娠d15注射LPS,LPS+NAC组在LPS处理前和(或)处理后经腹腔注射给予NAC。LPS处理后1.5h或6h处死孕鼠。结果LPS+NAC预处理组平均每窝死胎数明显低于LPS组;LPS+NAC后处理组平均每窝死胎数与LPS组比较无差异,LPS+NAC后处理组流产率高于LPS组;LPS+NAC预处理和后处理均抑制LPS引起IUGR。NAC预处理抑制LPS引起母肝、胎肝和胎盘组织脂质过氧化,LPS+NAC后处理抑制LPS引起母肝组织脂质过氧化,但对LPS引起的胎肝和胎盘组织脂质过氧化无抑制作用。进一步研究发现,母鼠妊娠期给予LPS后,血清TNF-α水平上升,NAC预处理抑制LPS引起血清和羊水TNF-α水平上升,而NAC后处理对LPS引起血清TNF-α水平上升无影响。结论NAC预处理预防LPS引起IUFD和IUGR;NAC后处理对LPS引起IUFD和IUGR无影响,反而加重早产。     

Effects of low-dose lipopolysaccharide (LPS) pretreatment on LPS-induced intra-uterine fetal death and preterm labor

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including embryonic resorption, intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR) and preterm delivery in rodents. The purpose of the present study was to investigate whether administration of a low-dose LPS to the pregnant mice induce a reduced sensitivity to subsequent high-dose LPS-induced IUFD and preterm labor. We found that LPS-induced IUFD was obviously attenuated when the pregnant mice were pretreated with low-dose LPS (10 microg/kg, i.p.) 24h before high-dose LPS (120 microg/kg, i.p.). Consistent with its protective effect, when administered 24h before high-dose LPS, low-dose LPS pretreatment obviously inhibited the releases of tumor necrosis factor alpha (TNF-alpha) in maternal serum and amniotic fluid and attenuated LPS-induced placental lipid peroxidation and GSH depletion. However, when administered 4h before high-dose LPS, low-dose LPS pretreatment did not induced a reduced sensitivity to subsequent high-dose LPS-induced release of TNF-alpha in maternal serum and amniotic fluid. Actually, low-dose LPS pretreatment 4h before high-dose LPS worsened LPS-induced oxidative stress in mouse placenta and increased nitric oxide production in maternal serum and amniotic fluid. Correspondingly, low-dose LPS pretreatment 4h before high-dose LPS aggravated LPS-induced IUFD. Taken together, these results indicate that whether a low-dose LPS exposure during pregnancy produce LPS hyporesponsiveness depends on the interval between the two doses of LPS. When administered 24h before high-dose LPS, a low-dose LPS pretreatment induces a reduced sensitivity to subsequent high-dose LPS-induced IUFD, TNF-alpha production and oxidative stress.     

Tumor necrosis factor alpha partially contributes to lipopolysaccharide-induced intra-uterine fetal growth restriction and skeletal development retardation in mice

Maternal infection is a cause of adverse developmental outcomes. Lipopolysaccharide (LPS)-induced embryonic resorption, intra-uterine fetal death (IUFD) and preterm labor have been well characterized. In the present study, we investigated the effects of maternal LPS exposure on intra-uterine fetal growth and skeletal development. All pregnant mice except controls received an intraperitoneal injection of LPS (75 microg/kg) on gestational days (GD) 15-17. The number of live fetuses, dead fetuses and resorption sites was counted on GD 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were examined and skeletal development was evaluated. As expected, perinatal LPS exposure resulted in 63.2% fetal death. LPS significantly lowered fetal weight, reduced crown-rump and tail lengths, and retarded skeletal ossification in caudal vertebrae, anterior and posterior phalanges, and supraoccipital bone. Additional experiment showed that a single dose of LPS (75 microg/kg, i.p.) on GD 15 increased the expression of TNF-alpha mRNA in maternal liver and placenta and TNF-alpha concentration in maternal serum and amniotic fluid. Furthermore, pentoxifylline, an inhibitor of TNF-alpha synthesis, significantly inhibited TNF-alpha production, reduced fetal mortality, and reversed LPS-induced fetal intra-uterine growth restriction and skeletal development retardation. Taken together, these results suggest that TNF-alpha is, at least in part, involved in LPS-induced intra-uterine fetal death, intra-uterine growth restriction and skeletal development retardation.     

Maternally-administered lipopolysaccharide (LPS) increases tumor necrosis factor alpha in fetal liver and fetal brain: its suppression by low-dose LPS pretreatment

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR) and neurological injury. In the LPS model, tumor necrosis factor alpha (TNF-alpha) is the major mediator leading to IUFD, IUGR and neurological injury. In the present study, we investigated the effect of maternally-administered LPS on TNF-alpha in maternal serum, amniotic fluid, fetal liver and fetal brain. The timed pregnant mice were intraperitoneally (i.p.) injected with a single dose of LPS (500microg/kg) on gestational day 17. As expected, TNF-alpha was obviously increased in maternal serum and amniotic fluid in response to LPS. Although maternally-administered LPS also increased the level of TNF-alpha protein in fetal liver and brain, no significant difference in TNF-alpha mRNA level in fetal liver and brain was observed among different groups, suggesting that the increased TNF-alpha protein in fetal liver and brain may be transferred from either the maternal circulation or amniotic fluid or placenta. When the pregnant mice were pretreated with a low-dose LPS (10microg/kg, i.p.) at 4, 12, 24 or 48h before LPS (500microg/kg, i.p.), LPS-evoked TNF-alpha in maternal serum and amniotic fluid was significantly inhibited. Importantly, low-dose LPS pretreatment also greatly attenuated LPS-induced increases in TNF-alpha protein in fetal liver and fetal brain. Taken together, these results indicate that perinatal exposure to low-dose LPS induces a reduced sensitivity to subsequent LPS challenge.     

Antioxidant activities of the flaxseed lignan secoisolariciresinol diglucoside, its aglycone secoisolariciresinol and the mammalian lignans enterodiol and enterolactone in vitro.

The flaxseed lignan secoisolariciresinol diglucoside (SDG) and mammalian lignans enterodiol (ED) and enterolactone (EL) were previously shown to be effective antioxidants against DNA damage and lipid peroxidation. Others reported inhibition of activated cell chemiluminescence by supra-physiological concentrations of secoisolariciresinol (SECO), ED and EL. Thus, we evaluated the antioxidant efficacy of potential physiological concentrations of SDG, SECO, ED and EL against 1,1-diphenyl-2-picrylhydrazyl (DPPH()), and 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH)-initiated peroxyl radical plasmid DNA damage and phosphatidylcholine liposome lipid peroxidation. SDG and SECO were effective (p<0.01) antioxidants against DPPH() at 25-200muM; whereas, ED and EL were inactive. Efficacy of lignans and controls against AAPH peroxyl radical-induced DNA damage was: SDG>SECO=17alpha-estradiol>ED=EL>genistein>daidzein. Lignan efficacy against AAPH-induced liposome lipid peroxidation was: SDG>SECO=ED=EL. Plant lignan antioxidant activity was attributed to the 3-methoxy-4-hydroxyl substituents of SDG and SECO, versus the meta mono-phenol structures of ED and EL. Benzylic hydrogen abstraction and potential resonance stabilization of phenoxyl radicals in an aqueous environment likely contributed to the antioxidant activity of the mammalian lignans. These represent likely extra- and intracellular antioxidant activities of flax-derived lignans at concentrations potentially achievable in vivo.     

Different antioxidant effects of polyphenols on lipid peroxidation and hydroxyl radicals in the NADPH-, Fe-ascorbate- and Fe-microsomal systems

Antioxidant and pro-oxidant effects of 14 naturally occurring polyphenols (PP) on rat liver microsomal lipid peroxidation (LP) and hydroxyl radical (*OH) production were studied in NADPH-dependent, 50 microM Fe(2+)-500 microM ascorbate (Fe-AA) or 50 microM Fe(2+) system, respectively. LP determined by the thiobarbituric acid method was inhibited in the NADPH system by flavonols and trans-resveratrol that were more effective than other flavonoids and derivatives of benzoic and cinnamic acid and were mostly more efficient than in the Fe-AA system. Inhibition of LP in the Fe system was higher by one order of magnitude than in the Fe-AA system. *OH production in the NADPH system, measured by formaldehyde production, was decreased by myricetin, fisetin and quercetin, but increased by kaempferol, morin and trans-resveratrol, indicating that z.rad;OH played a minor role in LP, which all of these PP inhibited. None of these PP at up to 40 microM concentration quenched *OH in the Fe-AA system. All tested PP, except trans-resveratrol and gentisic acid, spectrally interacted with Fe(2+) or Fe(3+), indicating formation of complexes or oxidation of PP. In contrast to the NADPH system we found no correlation between Fe(2+) chelation and inhibition of Fe-AA- or Fe-dependent LP indicating that iron chelation did not play a significant role in the two latter systems. It is concluded that the inhibition of LP by PP was apparently due to their hydrogen donating properties rather than chelation of iron.     

Protective effect of fluvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on copper-induced hydroxyl radical generation in the rat heart

The present study was examined the effect of fluvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on Cu(II)-induced hydroxyl radical generation (OH) in the extracellular fluid of rat myocardium. Rats were anesthetized and sodium salicylate in Ringer's solution (0.5 nmol/microl/min) was infused through a microdialysis probe to detect the generation of OH as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium. When Cu(II) was infused through the microdialysis probe, Cu(II) increased in OH formation trapped as 2,3-DHBA in the dialysate. When fluvastatin (100 microM) was administered to Cu(II) (50 microM)-pretreated animals, the levels of 2,3-DHBA at 300 min after administration of fluvastatin significantly decreased. In cumulative dose dependent experiments, three concentrations of Cu(II), 10, 25 and 50 microM, were infused through the microdialysis probe in the rat myocardium. A positive linear correlation between Cu(II) and the formation of 2,3-DHBA (R(2)=0.980) was observed. However, when corresponding experiments were performed with fluvastatin (100 microM) pretreated animals, the level of 2,3-DHBA decreased. These results suggest that blocking LDL oxidation by fluvastatin may attenuate Cu(II)-induced OH formation in the rat heart.     

Selective iNOS inhibition reduces renal damage induced by cisplatin

Cisplatin is a chemotherapeutic agent used in the treatment of several cancer tumors; however, nephrotoxicity has restricted its use. Reactive oxygen species and peroxynitrite, which is formed by the reaction between superoxide anion and nitric oxide (NO*), are implicated in cisplatin-induced nephrotoxicity. In contrast, both toxic and beneficial effects of NO* have been suggested in cisplatin-induced nephrotoxicity. Therefore, nowadays the role of NO* in this experimental model remains controversial. The aim of the present work was to elucidate the role of NO* in cisplatin-induced renal damage using N-[3-(aminomethyl)benzyl]acetamidine (1400W), a selective and irreversible inhibitor of iNOS. The mRNA levels of iNOS were increased in cisplatin-treated rats. The administration of 1400W reduced the cisplatin induced histological damage, renal dysfunction (increase in proteinuria and kidney injury molecule expression and decrease in creatinine clearance), tubulointerstitial infiltration, oxidative stress (increase in renal malondialdehyde and inmmunostaining for 4-hydroxy-2-nonenal) and nitrosative stress (immunostaining for 3-nitrotyrosine). In addition, the administration of 1400W was unable to modify systolic blood pressure in control rats. Our data demonstrate that selective iNOS inhibition reduces the cisplatin-induced nephrotoxicity and nitrosative stress which strongly suggest that in this experimental model (1) the NO* production is toxic and (2) iNOS is the main source of NO*.     

Prooxidant action of knipholone anthrone: Copper dependent reactive oxygen species generation and DNA damage

Knipholone (KP) and knipholone anthrone (KA) are natural 4-phenylanthraquinone structural analogues with established differential biological activities including in vitro antioxidant and cytotoxic properties. By using DNA damage as an experimental model, the comparative Cu(II)-dependent prooxidant action of these two compounds were studied. In the presence of Cu(II) ions, the antioxidant KA (3.1–200 μM) but not KP (6–384 μM) caused a concentration-dependent pBR322 plasmid DNA strand scission. The DNA damage induced by KA could be abolished by reactive oxygen species scavengers, glutathione and catalase as well as EDTA and a specific Cu(I) chelator bathocuproine disulfonic acid. In addition to Cu(II) chelating activity, KA readily reduces Cu(II) to Cu(I). Copper-dependent generation of reactive oxygen species and the subsequent macromolecular damage may be involved in the antimicrobial and cytotoxic activity of KA.     

Cardioprotective effects of a proanthocyanidin-rich fraction from Croton celtidifolius Baill: Focus on atherosclerosis

Proanthocyanidins are the most abundant polyphenols in human diets. Epidemiological studies have pointed to proanthocyanidins as promising molecules that could prevent the development of several coronary syndromes by inhibiting the atherogenic process. The present study was designed to investigate the antiatherogenic effects of a proanthocyanidin-rich fraction (PRF) obtained from Croton celtidifolius Baill (Euphorbiaceae) barks. In isolated human LDL, PRF caused a concentration-dependent inhibition of Cu²⁺-induced oxidative modifications, evidenced by the increasing of the lag phase of lipid peroxidation and decreasing in the oxidation rate (V_max), moreover, the protein moieties from LDL were protected against Cu²⁺-induced oxidation. In human umbilical vein endothelial cells (HUVECs), PRF reduced the ROS production stimulated by oxidized LDL. Herein, we demonstrate that oral treatment with PRF improved endothelium-dependent vasorelaxation in hypercholesterolemic LDL receptor knockout mice (LDLr^−/−), however, the fraction did not modify plasma lipids and atherosclerotic lesion size in this experimental model. Finally, our results showed for the first time that PRF prevent isolated LDL oxidation, decrease oxidative stress in endothelial cells and improve endothelial function in mice.     

Characterization of hydroxyl radical formation by microsomal enzymes using a water-soluble trap, terephthalate

Using terephthalic acid as a water-soluble trap, we characterized hydroxyl radicals (HO?) formation by liver microsomal enzymes from isoniazid-treated rats. We found that HO? formation was entirely dependent on intact microsomal enzymes, the presence of NADPH, and iron complexed with EDTA. In contrast to the other radical traps, we found no evidence that terephthalate is a substrate for cytochrome P450. Cumene hydroperoxide, an artificial supporter of cytochrome P450-catalyzed oxidation, failed to maintain HO(.-) formation. HO(.-) formation in liver microsomes was inhibited by the HO(.-) radical scavengers: dimethyl sulfoxide (DMSO), mannitol, and citrulline. It was abolished by catalase, but not superoxide dismutase (SOD), indicating that hydrogen peroxide was the sole precursor of the HO(.-). Therefore, the generation of hydroxyl radicals by microsomal enzymes appears to be dependent on two processes: (1) the rate of hydrogen peroxide production; and (2) the availability of iron ions or other transition metals for Fenton type reactions.     

Effects of (-)-nicotine and (-)-cotinine on 6-hydroxydopamine-induced oxidative stress and neurotoxicity: relevance for Parkinson's disease

In view of the apparent controversial properties of (-)-nicotine (NIC) in relation to both oxidative stress and neuroprotection, we studied the effects of NIC on hydroxyl radical (*OH) formation, oxidative stress production by 6-hydroxydopamine (6-OHDA) autoxidation in the presence and absence of ascorbate, and 6-OHDA neurotoxicity. Both NIC and (-)-cotinine (COT) exhibited increased *OH production during 6-OHDA autoxidation. Although the same effect was observed in *OH generation by the Fenton reaction (H2O2 + Fe2+), this reaction was completely prevented with the previous incubation of Fe2+ with NIC or COT. Furthermore, both NIC and COT demonstrated a capacity to be able to reduce the TBARS formation provoked in rat brain mitochondrial preparations by 6-OHDA autoxidation. This effect is assumed as a consequence of the action of NIC and COT on lipid peroxidation propagation. We treated with NIC (1mg/kg, i.p.) two 6-OHDA-induced rat models of Parkinson's disease. However, only in one of these models did we obtain clear evidence of a neuroprotective effect of NIC on nigrostriatal terminals, as revealed by immunohistochemistry against tyrosine hydroxylase. Thus, the antioxidant properties of both NIC and COT in relation to the lipid peroxidation induced by 6-OHDA autoxidation, together with their reported capacity to prevent the Fenton reaction, probably by sequestration of Fe2+, may contribute to an understanding of its neuroprotective properties. In addition, the reported capacity of both NIC and COT to increase the production of *OH by 6-OHDA autoxidation might help explain the controversial observation found under different experimental conditions.     

Antioxidant, prooxidant and cytotoxic activity of hydroxylated resveratrol analogues: structure-activity relationship

Resveratrol (trans-3,4',5-trihydroxystilbene), a naturally occurring hydroxystilbene, is considered an essential antioxidative constituent of red wine possessing chemopreventive properties. However, resveratrol and even more its metabolite piceatannol were reported to have also cytostatic activities. In order to find out whether this is related to antioxidative properties of those compounds, we synthesized five other polyhydroxylated resveratrol analogues and studied structure-activity relationships between pro-/antioxidant properties and cytotoxicity. Radical scavenging experiments with O(2)(*-) (5,5-dimethyl-1-pyrroline-N-oxide/electron spin resonance (DMPO/ESR)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (photometry) revealed that 3,3',4',5-tetrahydroxystilbene (IC(50): 2.69microM; k(9): 443000M(-1)s(-1)), 3,4,4',5-tetrahydroxystilbene (IC(50): 41.5microM; k(9): 882000M(-1)s(-1)) and 3,3',4,4',5,5'-hexahydroxystilbene (IC(50): 5.02microM), exerted a more than 6600-fold higher antiradical activity than resveratrol and its two other analogues. Furthermore, in HL-60 leukemic cells hydroxystilbenes with ortho-hydroxyl groups exhibited a more than three-fold higher cytostatic activity compared to hydroxystilbenes with other substitution patterns. Oxidation of ortho-hydroxystilbenes in a microsomal model system resulted in the existence of ortho-semiquinones, which were observed by ESR spectroscopy. Further experiments revealed that these intermediates undergo redox-cycling thereby consuming additional oxygen and forming cytotoxic oxygen radicals. In contrast to compounds with other substitution patterns hydroxystilbenes with one or two resorcinol groups (compounds 1 and 3) did not show an additional oxygen consumption or semiquinone formation. These findings suggest that the increased cytotoxicity of ortho-hydroxystilbenes is related to the presence of ortho-semiquinones formed during metabolism or autoxidation.     

Antioxidant properties of Thonningianin A,isolated from the African medicinal herb,Thonningia sanguinea

The antioxidant properties of Thonningianin A (Th A), an ellagitannin, isolated from the methanolic extract of the African medicinal herb, Thonningia sanguinea were studied using the NADPH and Fe2+/ascorbate-induced lipid peroxidation (LPO), electron spin resonance spectrometer and the deoxyribose assay. Th A at 10 microM inhibited both the NADPH and Fe2+/ascorbate-induced LPO in rat liver microsomes by 60% without inhibitory effects on cytochrome P450 activity. Th A was similar to the synthetic antioxidant, tannic acid, as an inhibitor of both the NADPH and Fe2+/ascorbate-induced LPO but potent than gallic acid, vitamin C and vitamin E. While Th A poorly scavenged the hydroxyl radical generated by the Fenton reaction it dose-dependently scavenged 1,1-diphenyl-2-picrylhydrazyl, superoxide anion and peroxyl radicals with IC50 of 7.5, 10 and 30 microM, respectively. Furthermore, Th A showed inhibitory effects on the activity of xanthine oxidase with an IC50 of 30 microM. In the deoxyribose assay both T. sanguinea and its methanolic component Th A showed only site-specific (Fe3+ + H2O2) but not non-site-specific (Fe3+ + EDTA + H2O2) hydroxyl radical scavenging suggesting chelating ability for iron ions. Spectroscopic studies showed that Th A enhanced absorbance in the visible region in the presence of Fe2+ ions. These results indicate that the antioxidant properties of Th A involve radical scavenging, anti-superoxide formation and metal chelation.     

Investigating the potential neuroprotective effects of statins on DNA damage in mouse striatum

We investigated the protective effect of pravastatin, simvastatin and atorvastatin on striatal DNA damage as a potential method to conserve and protect the nigrostriatal neurons. C57Bl/J6 mice were treated with combinations of a statin and the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). DNA damage, DNA sensitivity to H(2)O(2)in vitro, and DNA repair capacity was measured using the single cell gel electrophoresis (comet) assay. MPTP treatment increased DNA damage in the striatum. Contrary to expectation, the statins studied here did not protect DNA against H(2)O(2) induced damage but did in fact cause DNA damage. Treatment with simvastatin showed a significant increase in levels of DNA damage (p0.0018) and DNA damage induced in vitro with H(2)O(2) was significantly increased by pravastatin (p0.0001). DNA repair and repair capacity was slightly increased by simvastatin, significantly increased by pravastatin (p=0.0093), but slightly decreased by atorvastatin. In the MPTP treated groups, pre-treated with statins, pravastatin (p0.0036) and simvastatin (p0.021), increased the level of DNA damage, while atorvastatin did not exhibit a significant effect. All three statins, administered prior to MPTP, offered slight protection against H(2)O(2) induced DNA damage and simvastatin and atorvastatin decreased the DNA repair capacity of the cells insignificantly. Treatment with statins, under the experimental conditions used, increased baseline levels of DNA damage, but DNA repair processes were left intact because the amount of repair also increased. Oxidative damage, however, largely exceeded the extent of DNA repair of mice treated with both the statins and MPTP.     

Comparative study on antioxidant activity of different varieties of commonly consumed legumes in India

Legumes are rich source of proteins, dietary fiber, micronutrients and bioactive phytochemicals. Thirty different varieties of commonly consumed legumes in India, were screened for phenolic content and antioxidant activity using, radical scavenging [(1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid, (ABTS⁺)], Ferric Reducing Antioxidant Power (FRAP) and metal ion (Fe²⁺) chelation assays. Legumes varied largely in their antioxidant activity. Horse gram, common beans, cowpea (brown and red) and fenugreek showed high DPPH radical scavenging activity (>400 units/g), while lablab bean (cream and white), chickpea (cream and green), butter bean and pea (white and green) showed low antioxidant activity (<125 units/g). Green gram, black gram, pigeon pea, lentils, cowpea (white) and common bean (maroon) showed intermediate activity. Similar trend was observed when the activity was assessed with ABTS⁺ and FRAP assays. Thus most of the varieties having light color seed coat, except soybean exhibited low antioxidant activity. While legumes having dark color seed coat did not always possessed high antioxidant activity (e.g. moth bean, black pea, black gram, lentils). Antioxidant activity showed positive correlation (r² > 0.95) with phenolic contents, in DPPH, ABTS⁺ and FRAP assays, whereas poor correlation (r² = 0.297) was observed between Fe²⁺ chelating activity of the legumes and phenolic contents.     

Intracellular generation of reactive oxygen species by mitochondria

Mitochondria have bioenergetic properties that strongly suggest their involvement in the cellular formation of reactive oxygen species (ROS). Apparent confirmation of this process has come from work with isolated mitochondria, which have been shown to produce H(2)O(2) from dismutating superoxide radicals. Two different sites were reported to shuttle single electrons to oxygen out of the normal respiratory sequence. However, the mechanisms for ROS formation at these two sites are controversial. Arguments against mitochondrial ROS formation in the living cell are based on the fact that bioenergetic alterations may result from the mechanical removal of mitochondria from their natural environment. Furthermore, the invasive detection methods that are generally used may be inappropriate because of the possible interaction of the detection system with mitochondrial constituents. The use of non-invasive detection methods has proved that ROS formation does not occur unless changes in the physical state of the membrane are established. The aim of this commentary is to discuss critically the arguments in favor of mitochondria as the main intracellular source of ROS. The pros and cons of working with isolated mitochondria, as well as the detection methodology are carefully analyzed to judge whether or not the above assumption is correct. The conclusion that mitochondria are the main ROS generators in the cell contradicts the fact that ROS release was not observed. However, if electron flow from ubiquinol to the bc(1) complex is hindered due to changes in lipid fluidity, single electrons may transfer to dioxygen and produce H(2)O(2) via superoxide radicals.