Biofactors - Volume 19, issue 1-2

Article Type: Other

Citation: BioFactors, vol. 19, no. 1-2, pp. 1-1, 2003

Authors: Flohé, Leopold | Budde, Heike | Hofmann, Birgit

Article Type: Research Article

Abstract: Peroxiredoxins constitute a family of peroxidases that lack prosthetic groups or catalytically active heteroatoms. Instead, their peroxidatic activity is due to a strictly conserved cysteine that is activated within a novel catalytic triad in which the cysteine thiol is coordinated to an arginine and a threonine or serine residue. Donor substrates are thiol compounds which differ between subtypes of peroxiredoxins and species. In pathogenic trypanosomatids that lack heme- or seleno-peroxidases peroxiredoxins have …been shown to represent the major devices to detoxify hydroperoxides and an equivalent role may be assumed for other protozoal parasites and many bacterial pathogens. In mammals equipped with more efficient peroxidases the peroxiredoxins appear to be responsible for the redox regulation of diverse metabolic processes. The substantial differences in the cosubstrate requirements of the peroxiredoxins of pathogenic microorganisms and their mammalian host may be exploited to selectively inhibit the antioxidant defense of pathogens. Thereby, the pathogen would be more readily eliminated by the innate immune response of the host's phagocytes. Show more

Citation: BioFactors, vol. 19, no. 1-2, pp. 3-10, 2003

Authors: Wiernsperger, N.F.

Article Type: Research Article

Abstract: The implication of oxidative stress (OS) in diabetes is a major concern for the development of therapeutics aimed at improving the metabolic and/or vascular dysfunctions of this burdening disease. Ample evidence is available suggesting that OS is present in essentially all tissues and can even be observed in prediabetic states. This raises the question of the origin of OS and suggests that, although hyperglycemia is largely linked with free radical production, its role may mainly be …the aggravation of a preexisting state. Indeed other factors are also causally linked to OS, such as hormones and lipids. The main debate is about the pertinence of antioxidant therapy since the large scale clinical trials performed recently have essentially failed to show any significant improvement in metabolic or vascular disturbances of diabetic patients. However this conclusion must be tempered by the fact that they have mainly been using vitamin E +/-C; indeed many arguments suggest that either the choice or the application modalities of these substances may have been inadequate. Potential reasons for the actual failure of antioxidant therapy in diabetes are discussed; the indisputable involvement of OS in this disease still leaves hope for alternative therapeutic approaches. Show more

Keywords: oxidative stress, diabetes mellitus

Citation: BioFactors, vol. 19, no. 1-2, pp. 11-18, 2003

Authors: Dünschede, Fritz | Zwicker, Klaus | Ackermann, Hanns | Zimmer, Guido

Article Type: Research Article

Abstract: Purified ATPsynthase of bovine heart mitochondria has been analyzed for its mobility and reactivity of oligomycin-sensitive sulfhydryl regions in presence of the substrate ADP and oligomycin. Labeling of thiol groups at the hydrophobic F_0 region of the ATPsynthase was increased in the enzyme initially treated with SDS, N-ethylmaleimide and dithiothreitol (modified enzyme). After dialysis or gel permeation the ATPsynthase was treated with [^{14} C] alpha lipoic acid at a molar ratio of 35–85/1 …(lipoic acid/ATPsynthase) corresponding to 4–8.6 nmol/mg protein. Under these conditions, ATPase activity of the native enzyme was significantly decreased. After preincubation with ADP, PAGE of the native, [^{14} C] labeled enzyme revealed an increase of radioactivity at a region of 25 kDa deduced to Cys 197 of subunit b. In the modified enzyme the increase in radioactivity was found at 10 kDa. In this context, the sequence Lys-Cys-Ile around Cys 197 of subunit b suggests excessive reactivity of this thiol, as well as ready reversibility by –SH-S-S- interchange. Therefore, previously observed reaction by thiol reagents and antioxidants from outside the mitochondrion can be interpreted with Cys 197 of F_0 b. It accounts for sulfhydryl unmasked by binding of ADP at F1. Show more

Keywords: oligomycin-sensitive thiols, F_0F_1 ATPsynthase, bovine, Labeling by ^{14}C-alpha lipoic acid, ATPase activity, PAGE, thiol-containing subunits, primary protein structure and thiol reactivity

Citation: BioFactors, vol. 19, no. 1-2, pp. 19-32, 2003

Authors: Tang, Man Ho | Chiu, Po Yee | Ko, Kam Ming

Article Type: Research Article

Abstract: In the present study, we investigated the differential role of the mitochondrial glutathione status and induction of heat shock proteins (HSPs) 25/70 in protecting against carbon tetrachloride (CCl_4 ) hepatotoxicity in schisandrin B (Sch B)-pretreated mice. The time-course of Sch B-induced changes in these hepatic parameters were examined. Dimethyl diphenyl bicarboxylate (DDB), a non-hepatoprotective analog of Sch B, was studied for comparison. Sch B treatment (2 mmol/kg) produced maximal enhancement in hepatic …mitochondrial glutathione status as well as increases in hepatic HSP 25/70 levels at 24 h post-dosing. The stimulatory effect of Sch B then gradually subsided, but the activities of hepatic mitochondrial glutathione reductase (GR) and glutathione S-transferases (GST) as well as the level of HSP 25 remained relatively high even at 72 h post-dosing. CCl_4 challenge caused significant impairment in mitochondrial glutathione status and a decrease in HSP 70 level, but the HSP 25 level was significantly elevated. While the extent of hepatoprotection afforded by Sch B pretreatment against CCl_4 was found to inversely correlate with the time elapsed after the dosing, the protective effect was associated with the ability of Sch B to maintain the mitochondrial glutathione status and/or induce further production of HSP 25 in CCl_4 -intoxicated condition. On the other hand, DDB treatment (2 mmol/kg), which did not increase mitochondrial GSH level and GST activity or induce further production of HSP 25 after CCl_4 challenge, could not protect against CCl_4 toxicity. The results suggest that the enhancement of mitochondrial glutathione status and induction of HSP 25/70 may contribute independently to the hepatoprotection afforded by Sch B pretreatment. Show more

Keywords: Schisandrin B, carbon tetrachloride, liver, mitochondrion, glutathione, heat shock protein

Citation: BioFactors, vol. 19, no. 1-2, pp. 33-42, 2003

Authors: Chiu, Po Yee | Ko, Kam Ming

Article Type: Research Article

Abstract: In the present study, we examined the time-dependent changes in the mitochondrial glutathione status and ATP generation capacity in the myocardium as well as the susceptibility of the myocardium to ischemia-reperfusion (IR) injury in female Sprague Dawley rats treated with a single pharmacological dose (1.2 mmol/kg) of schisandrin B (Sch B). Sch B treatment produced a time-dependent enhancement in myocardial mitochondrial glutathione status, as evidenced by increases in myocardial mitochondrial reduced glutathione (GSH) …level and activities of glutathione reductase, Se-glutathione peroxidase (GPX) and glutathione S-transferases, with the response reaching maximum at 48 h post-dosing and then declining gradually to the control level at 96 h post-dosing. The enhancement of mitochondrial glutathione status was associated with an increase in myocardial ATP generation capacity, with the value peaking at 72 h post-dosing. These beneficial effects of Sch B on the myocardium was paralleled by a time-dependent decrease in the susceptibility to IR injury, with the maximum protection demonstrable at 48 h post-dosing. The cardioprotection was associated with increases in myocardial GSH level and activities of glutathione antioxidant enzymes (except for GPX whose activity was suppressed) as well as tissue ATP level/ATP generation capacity. The results suggest that Sch B treatment can precondition the myocardium by enhancing the mitochondrial glutathione status and ATP generation capacity, thereby protecting against IR injury. Show more

Keywords: Schisandrin B, ischemia-reperfusion, myocardium, mitochondrion, glutathione, ATP

Citation: BioFactors, vol. 19, no. 1-2, pp. 43-51, 2003

Authors: Laksmitawati, D.R. | Handayani, S. | Udyaningsih-Freisleben, S.K. | Kurniati, V. | Adhiyanto, C. | Hidayat, J. | Kusnandar, S. | Dillon, H.S.D. | Munthe, B.G. | Wirawan, R. | Soegianto, R.R. | Ramelan, W. | Freisleben, H.J.

Article Type: Research Article

Abstract: A study on thalassemia intermedia and major patients in Jakarta was initiated to obtain a comprehensive picture of metabolic dysregulation, iron overload, oxidative stress, and cell damage. Data are presented from a group of 14 transfusion-dependent patients in an age range of 11–25 years (T) and another group of 9 frequently transfused (for at least 15 years) patients aged 17–30 years (L). A third group comprised 6 patients (aged 7 to 14 years) who had not …yet obtained transfusions (N). The 21 controls (C) were voluntary students without diagnosis or clinical signs of thalassemia up to 30 years of age. The study was approved by the Ethical Clearance Board of the Medical Faculty and all blood samples from controls and patients were obtained on fully informed consent. Levels of antioxidants (vitamins A, C, E and β-carotene) and reactive thiols are considerably decreased in transfused patients, whereas signs of iron overload and cell damage are increased (serum iron, ferritin, transferrin saturation, SGOT, SGPT, γ-GT, bilirubin). Results can be summarized that non-transfused thalassemia intermedia patients exert slight signs of oxidative stress, and increased hemoglobin degradation but no significant indication of tissue or cell damage. This picture differs considerably from transfusion-dependent thalassemia major patients: highly significant decrease in antioxidants and thiols and tremendous iron overload and cell damage. The picture is even worsened in long-term transfused patients. Iron chelation after transfusion is not sufficient in Indonesia, because it is normally (with few exceptions) applied only once together with transfusion. Hence, one major reason of the bad condition of transfusion-dependent thalassemia patients in Indonesia appears to be frequent transfusions (on the average one per month) and insufficient chelation of one treatment per month together with transfusion. Show more

Keywords: thalassemia major, thalassemia intermedia, iron status, transfusion, oxidative stress

Citation: BioFactors, vol. 19, no. 1-2, pp. 53-62, 2003

Authors: Kartal Özer, Nesrin | Negis, Yesim | Aytan, Nurgul

Article Type: Research Article

Abstract: The development of atherosclerosis is a multifactorial process in which both elevated plasma cholesterol levels and proliferation of smooth muscle cells play a central role. Numerous studies have suggested the involvement of oxidative processes in the pathogenesis of atherosclerosis and especially of oxidized low density lipoprotein. Some epidemiological studies have shown an association between high dietary intake and high serum concentrations of vitamin E and lower rates of ischemic heart disease. Cell …culture studies have shown that α-tocopherol brings about inhibition of smooth muscle cell proliferation. This takes place {via} inhibition of protein kinase C activity. α-Tocopherol also inhibits low density lipoprotein induced smooth muscle cell proliferation and protein kinase C activity. The following animal studies showed that vitamin E protects development of cholesterol induced atherosclerosis by inhibiting protein kinase C activity in smooth muscle cells in vivo. Elevated plasma levels of homocysteine have been identified as an important and independent risk factor for cerebral, coronary and peripheral atherosclerosis. However the mechanisms by which homocysteine promotes atherosclerotic plaque formation are not clearly defined. Earlier reports have been suggested that homocysteine exert its effect via H_2 O_2 produced during its metabolism. To evaluate the contribution of homocysteine in the pathogenesis of vascular diseases, we examined whether the homocysteine effect on vascular smooth muscle cell growth is mediated by H_2 O_2 . We show that homocysteine induces DNA synthesis and proliferation of vascular smooth muscle cells in the presence of peroxide scavenging enzyme, catalase. Our data suggest that homocysteine induces smooth muscle cell growth through the activation of an H_2 0_2 independent pathway and accelerate the progression of atherosclerosis. The results indicate a cellular mechanism for the atherogenicity of cholesterol or homocysteine and protective role of vitamin E in the development of atherosclerosis. Show more

Keywords: cholesterol, homocysteine, vitamin E, atherosclerosis

Citation: BioFactors, vol. 19, no. 1-2, pp. 63-70, 2003

Authors: Safitri, Ratu | Tarigan, Ponis | Freisleben, Hans Joachim | Rumampuk, Rymond J. | Murakami, Akira

Article Type: Research Article

Abstract: Two antioxidant compounds were isolated from C. sappan L by multiple steps of column chromatography and thin layer chromatography in succession with superoxide scavenging assay as activity monitor. Structures of the two compounds were determined by spectroscopic methods as 1',4'-dihydro-spiro[benzofuran-3(2H),3'-[3H-2]benzopyran]-1',6',6',7'-tetrol (compound 1) and 3-[[4,5-dihydroxy-2(hydroxymethyl) phenyl]-methyl]-2,3-dihydro-3,6-benzofurandiol (compound 2). Characterization of antioxidant properties of these two compounds was done by determining the inhibitory effect on xanthine oxidase activity as well …as scavenging effect on superoxide anion and hydroxyl radicals. Our results indicated that compounds 1 and 2 inhibited xanthine oxidase activity and scavenged superoxide anion and hydroxyl radicals. Compounds 1 and 2 possessed similar radical scavenging activities as ascorbic acid, and they were more effective than other well-known antioxidants such as α-tocopherol, β-carotene, and BHT. As inhibitors of free radical formation, compounds 1 and 2 were more effective than all the other antioxidants tested. In conclusion, compounds 1 and 2 can be regarded as primary antioxidants with radical-scavenging and chain-breaking activities as well as secondary antioxidants with inhibitory effect on radical generation. Show more

Keywords: flavonoids, free radicals, antioxidants, xanthine oxidase, Caesalpinia sappan

Citation: BioFactors, vol. 19, no. 1-2, pp. 71-77, 2003

Authors: Nohl, Hans | Bieberschulte, Werner | Dietrich, Barbara | Udilova, Natalia | Kozlov, Andrey V.

Article Type: Research Article

Abstract: Here we show that lipid peroxidation of liposomal membranes was suppressed in the presence of Caroverine, a spasmolytic drug used in some countries. In order to understand the mechanism of this antioxidant action of Caroverine we studied the interaction of Caroverine with superoxide radicals, hydroxyl radicals and peroxynitrite. The results of the study show that the reaction of Caroverine with O_2^{-•} radicals is of marginal significance. However, it is efficient in removing peroxynitrite and a …particular high reaction constant was found for reaction with hydroxyl radicals. The strong antioxidant activity of Caroverine is therefore based both on the partial prevention of the formation and the highly active scavenging of hydroxyl radicals. Show more

Keywords: caroverine, lipid peroxidation, electron paramagnetic resonance, oxidative stress, hydroxyl radical, superoxide radical, peroxynitrite

Citation: BioFactors, vol. 19, no. 1-2, pp. 79-85, 2003

Authors: Udyaningsih-Freisleben, Seruni K. | Kurniati, Vita | Prasetyo, Pamulih B. | Handayani, Sri | Adhiyanto, Chris | Soegianto, Rondang R. | Pudiantari, Ratna | Munthe, Bulan G. | Ramelan, Wahyuning | Freisleben, Hans-Joachim

Article Type: Research Article

Abstract: Erythrocyte membrane structural parameters were studied in transfusion-dependent β-thalassemia patients, in long-term transfused patients (regularly transfused < 15 years), and in those who had not yet obtained transfusions. Controls were voluntary students up to 30 years of age without diagnosis or clinical signs of thalassemia. Membranes were isolated and investigated by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electron paramagnetic resonance (EPR) spectroscopy. Data obtained from the thiol-reactive spin label …N-ethyl-maleimidoproxyl reveal immobilization of protein environment in erythrocyte membranes from thalassemic patients. SDS-PAGE shows both degradation and aggregation of membrane proteins. Thalassemic erythrocyte membranes exert higher order parameters in the hydrophobic region as determined by 16-doxyl-stearic acid. Rotational correlation times of this spin label increase only in transfused patients. Polarity is higher in membranes of all patients than in controls. In the polar interface, order parameters obtained from 5-doxyl-stearic acid increase in non-transfused and decrease in transfusion-dependent patients as compared with controls. Transfused patients exert increasing membrane order in the hydrophobic region and counter-currently decreasing order in the polar interface indicating loss of membrane integrity along with the loss of fluidity and polarity gradients and the loss the energetic barrier function of the membrane. Show more

Keywords: thalassemia major, thalassemia intermedia, transfusion, erythrocyte membrane, EPR spectroscopy

Citation: BioFactors, vol. 19, no. 1-2, pp. 87-100, 2003