Antioxidant and pro-oxidant effects of epinephrine and isoprenaline on peroxidation of LDL and lipid liposomes.

Antioxidant or pro-oxidant properties of epinephrine (EPI) and isoprenaline (ISO) were studied in the absence and presence of Fe2+, Fe3+ and Cu2+ ions. EPI and ISO (>2 micromol/l) inhibited peroxidation of low density lipoprotein (LDL) induced by 2, 2'-azobis(2-amidino-propane) (AAPH). EPI had a similar inhibitory potency as ISO, but their potency was several times higher than the potency of alpha-tocopherol (alpha-TOC). When the LDL peroxidation was induced by 5 micromol/l CuSO4, EPI and ISO enhanced LDL peroxidation at low concentrations (10micromol/l) and decreased peroxidation at higher concentrations (30 micromol/l). The compounds had a similar tendency to inhibit the peroxidation of phosphatidylcholine liposomes. EPI (3-30 micromol/l) inhibited lipid peroxidation of phosphatidylcholine liposomes induced by 2 mmol/l of AAPH, but it was less effective and even increased the peroxidation, when the samples contained 2 mmol/l AAPH with 50 micromol/l FeSO4 or 2 mmol/l AAPH with 20 micromol/l FeCl3. Inhibition of lipid peroxidation by EPI was also observed when studying decreased oxygen consumption, when the peroxidation of linoleic acid was induced by lipoxidase. In conclusion, EPI and ISO reduced lipid peroxidation, but they exhibit pro-oxidant properties in the presence of Fe2+, Fe3+ or Cu2+ ions, depending on the catecholamine and ionic concentration.

Interaction of nitric oxide with 2-thio-5-nitrobenzoic acid: implications for the determination of free sulfhydryl groups by Ellman's reagent.

Nitric oxide (NO) in an aerobic environment, reacts with the sulfhydryl groups of proteins to form nitroso thiols. Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid), DTNB, is widely used for the determination of -SH groups. In this procedure, DTNB, a symmetric aryl disulfide, reacts with the free thiol to give a mixed disulfide plus 2-nitro-5-thiobenzoic acid (TNB) which is quantified by its absorbance at 412 nm. We observed that the presence of NO during the determination of SH groups in a reaction system containing glutathione (GSH) or bovine serum albumin (BSA) plus DTNB resulted in an inhibition in the detection of TNB. Addition of NO donors or NO gas after TNB was already formed led to the bleaching of yellow color and loss of absorbance at 412 nm. These interactions did not occur under anaerobic conditions. Decreased formation of TNB therefore appeared to be due not only to destruction of SH groups of BSA or GSH by NO (S-nitrosation) and consequently to lower TNB formation, but also to direct reaction of NO/O2 with TNB. The mechanism(s) of inhibition of accumulation of TNB by NO was evaluated. NO generated by DEA/NO, SNAP, or spermine/NO, as well as gaseous NO or BSA-NO, directly interacted with TNB, followed by decreased absorbance at 412 nm in a concentration- and time-dependent manner. Kinetics of NO/O2 interaction with TNB were dependent on the ability of the NO donors to release NO as the donors with a short half-life bleached the yellow color of TNB faster. The requirement for O2 suggests that nitrogen oxide or higher oxides of NOx are responsible for interaction with TNB. The UV/VIS spectrum of the final product formed during the interaction of NO with TNB was identical to that of DTNB. These results suggest that interaction of NO (NOx) with TNB resulted in the formation of an unstable nitrosothiol, followed by oxidation and dimerization back to the corresponding disulfide, DTNB. Therefore, determination of SH groups in proteins by Ellman's reagent after or in the presence of NO treatment is complicated since the reduced form of DTNB, TNB, can be reoxidized by NO back to DTNB, with subsequent loss of absorbance at 412 nm.

Nafazatrom inhibits peroxidation of phosphatidylcholine liposomes, heart homogenate and low density lipoproteins.

In order to contribute to the understanding of the biological properties of nafazatrom, an antithrombotic agent (NAP), we studied its effects on peroxidation of low density lipoproteins (LDL), lipid liposomes, heart homopgenate, and its interaction with alpha-tocopherol radical. NAP decreased the FeSO4 and H202-induced peroxidation of phosphatidylcholine liposomes and heart homogenate, and it decreased peroxidation of LDL induced by CuSO4 or 2,2'-azobis(2-amidinopropane). The antioxidant effect of NAF was about 3 times less potent than that of alpha-tocopherol (alpha-TOC) in phosphatidylcholine liposomes, and NAF was about 2-4 times more efficient to decrease peroxidation of LDL than alpha-TOC. Possible interaction of NAF with alpha-tocopherol radical (alpha-TR) was studied by EPR spectroscopy. NAF decreased the concentration of alpha-TR, but it was about 100-times less efficient than vitamin C. This may indicate that NAF does not interfere with alpha-TR formation and/or reduction of alpha-TR in biological system. The obtained results may help the explanation of biological effects of NAF.

Inhibition of rat and human cytochrome P4502E1 catalytic activity and reactive oxygen radical formation by nitric oxide.

Nitric oxide (NO) reacts with heme-containing enzymes, including certain isoforms of cytochrome P450. Cytochrome P4502E1 (CYP2E1) is induced by ethanol and plays an important role in the toxicity of ethanol and other hepatotoxins. CYP2E1 is also very effective in generating reactive oxygen intermediates such as superoxide radical and H2O2, oxidizing ethanol to the 1-hydroxyethyl radical, and has a high NADPH oxidase activity. The effect of NO on CYP2E1 catalytic activity and generation of reactive oxygen intermediates was evaluated. Incubating liver microsomes isolated from rats treated with pyrazole to induce high levels of CYP2E1, with gaseous NO or NO released from a variety of NO donors such as SNAP, DEA/NO, spermine/NO, and GSNO, resulted in a loss of CYP2E1 catalytic activity with specific substrates such as p-nitrophenol or dimethylnitrosamine. Trapping of NO with hemoglobin resulted in protection of CYP2E1 activity against the inactivation by NO. There was no effect by analogues of the donors which do not release NO nor was there any effect by NO on NADPH-cytochrome P450 reductase activity. Inactivation of CYP2E1 by NO was not prevented by superoxide dismutase or catalase, suggesting that superoxide, H2O2, or peroxynitrite were not responsible for the actions of NO. The inactivated CYP2E1 was not degraded nor did it lose its epitope sites as shown by Western blot analysis. Associated with loss of CYP2E1 catalytic activity was a decrease in the formation of superoxide radical and H2O2, in microsomal lipid peroxidation catalyzed by low, but not high concentration of iron, and in consumption of NADPH. Oxidation of ethanol to the 1-hydroxyethyl radical was also inhibited by NO. ESR experiments indicated the formation of stable heme-NO complexes with CYP2E1. NO appears to compete with O2 and CO for binding to CYP2E1 as incubation with gaseous NO, or NO donors inhibited formation of the characteristic CO binding spectrum of P450. Microsomes isolated from a stably transfected HepG2 cell line expressing only CYP2E1 were also inactivated by NO, validating interaction of NO with this isoform of P450. These results indicate that NO inhibits CYP2E1 catalytic activity and generation of reactive radical intermediates. NO may prevent toxicity of agents which require bioactivation by P450 isoforms such as CYP2E1 and in generation of reactive intermediates by CYP2E1.

Inhibition of the catalytic activity of alcohol dehydrogenase by nitric oxide is associated with S nitrosylation and the release of zinc.

Nitric oxide (NO) reacts with the sulfhydryl groups of proteins to form nitroso thiols. Alcohol dehydrogenase (ADH) plays an important role in the metabolism of ethanol. Chronic alcohol administration stimulates NO formation in the liver, and production of NO is increased in alcohol liver injury. The effect of exogenous and endogenous NO on rat or horse ADH activity was evaluated. Incubation of intact rat hepatocytes or cytosol isolated from hepatocytes with S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide donor, resulted in a decrease in ADH activity. Endogenous NO synthesis was induced in rat hepatocytes by incubation with a mixture of cytokines and endotoxin in the presence of L-arginine. As NO production in hepatocytes increased over a 24 h time period, a significant decrease in ADH activity was observed. This effect was blocked by the competitive inhibitor of NO synthesis, N omega-nitro-L-arginine methyl ester, indicating that ADH was also inactivated by endogenously generated NO. The decreased activity of ADH was not related to lowering of the ADH content as shown by Western blot analysis. To evaluate the mechanism of inhibition, purified ADH from equine liver was incubated with gaseous NO or NO released from NO donors such as the diethylamine/nitric oxide complex (DEA/NO) and SNAP. NO donors inactivated ADH in a dose- and time-dependent manner. Trapping of NO with hemoglobin resulted in protection of ADH against inactivation by NO. There was no effect by analogues of the NO donors which do not release NO. NAD afforded some protection against the NO inactivation of ADH. Measurements of thiol oxidation, S nitrosylation, and zinc release were used to assess the effect of NO on ADH activity. Thiol oxidation, S-nitroso thiol formation, and zinc release correlated with inactivation of ADH by NO, indicating that disruption of the zinc/thiolate active center due to S nitrosylation of ADH results in zinc release, followed by inactivation of the enzyme. Recovery experiments were performed by incubating the NO-treated enzyme with dithiothreitol (DTT) and/or Zn2+. The inhibitory effect by NO was reversible since, after the nitrosylated enzyme was reduced with DTT followed by incubation with ZnCl2 to allow reincorporation of Zn2+, ADH activity was increased from 20% of control values to 70%. These results suggest that cysteine residues contained within the zinc/thiolate active center may be primary sites of NO interaction with ADH. NO may modulate the metabolism of ethanol and influence metabolic actions of ethanol via interaction with ADH.

Increased cytotoxicity of 3-morpholinosydnonimine to HepG2 cells in the presence of superoxide dismutase. Role of hydrogen peroxide and iron.

3-Morpholinosydnonimine (SIN-1) is widely used to generate nitric oxide (NO(x).) and superoxide radical (O2-.). The effect of SOD on the toxicity of SIN-1 is complex, depending on what is the ultimate species responsible for toxicity. SIN-1 (< 1 mM) was only slightly toxic to HepG2 cells. Copper, zinc superoxide dismutase (Cu,Zn-SOD) or manganese superoxide dismutase (Mn-SOD) increased the toxicity of SIN-1. Catalase abolished, while sodium azide potentiated, this toxicity, suggesting a key role for H2O2 in the overall mechanism. Depletion of GSH from the HepG2 cells also potentiated the toxicity of SIN-1 plus SOD. Although Me2SO, sodium formate, and mannitol had no protective effect, iron chelators, thiourea and urate protected the cells against the SIN-1 plus Cu,Zn-SOD-mediated cytotoxicity. The cytotoxic effect of Cu,Zn-SOD but not Mn-SOD, showed a biphasic dose response being most pronounced at lower concentrations (10-100 units/ml). In the presence of SIN-1, Mn-SOD increased accumulation of H2O2 in a concentration-dependent manner. In contrast, Cu,Zn-SOD increased H2O2 accumulation from SIN-1 at low but not high concentrations of the enzyme, suggesting that high concentrations of the Cu,Zn-SOD interacted with the H2O2. EPR spin trapping studies demonstrated the formation of hydroxyl radical from the decomposition of H2O2 by high concentrations of the Cu,Zn-SOD. The cytotoxic effect of the NO donors SNAP and DEA/NO was only slightly enhanced by SOD; catalase had no effect. Thus, the oxidants responsible for the toxicity of SIN-1 and SNAP or DEA/NO to HepG2 cells under these conditions are different, with H2O2 derived from O2-. dismutation playing a major role with SIN-1. These results suggest that the potentiation of SIN-1 toxicity by SOD is due to enhanced production of H2O2, followed by site-specific damage of critical cellular sites by a transition metal-catalyzed reaction. These results also emphasize that the role of SOD as a protectant against oxidant damage is complex and dependent, in part, on the subsequent fate and reactivity of the generated H2O2.

Effect of illuminated nifedipine, a potent antioxidant, on intestinal and vascular smooth muscles.

1. The effects of nifedipine (Nif) and its illuminated nitroso product nitrosopine (NTP) were investigated on lipid peroxidation, KCl elevated smooth muscle tension, and ionic currents of single smooth muscle cells. 2. Illumination of Nif at 400-700 nm within 24-48 h changed it completely to a potent antioxidant, NTP. 3. Nif relaxed the KCl-induced contractions of guinea-pig taenia caeci and rat aorta and reduced the amplitude of the evoked inward Ca2+ current of taenia caeci cells in a concentration-dependent manner. NTP (up to 100 microM) was ineffective in this respect. Pretreatment by NTP (10 microM) did not affect the actions of Nif. 4. The evidence suggests that NTP, generated by day-light illumination from Nif, exerts antioxidant activity but is devoid of voltage-dependent Ca2+ channel (VDC) blocking property and does not interfere with the action of Nif on the smooth muscle cell membrane VDC.

[Smooth muscle preparations as models for studies of drug effects on organs]. / Hladkosvalové preparáty ako modelové orgány stúdia úcinku farmák.

The action of drugs on processes in smooth muscles, in their innervation or mucosa results in changes in contractility of the gut, airways, vessels and urogenital system. Noteworthy insight has been gained into the basic common characteristics ot smooth muscles as well as into special properties of individual smooth muscle types whose fundamental properties have become adapted to a particular situation. This insight along with knowledge on the subcellular and cellular organization of smooth muscle cells and of their innervation, on the role of the mucosa, and introduction of sophisticated electrophysiological, biochemical, isotopic and morphological methods makes smooth muscle suitable for investigation of elemental physiological and pathophysiological processes and of targets of drug action. The complexity of the smooth muscle tissue allows to study the mechanisms of drug action on the peripheral cholinergic, adrenergic, nonadrenergic-noncholinergic nerves and their neuromediators, on the epithelial and endothelial cells and the biologically active substances which they release, on the membrane and subcellular receptors, receptor coupled processes, ion channels, enzymes, Ca2+ availability, etc. Since most of these mechanisms operate also in other tissues, the obtained results may characterize drug action in other systems as well.

[Endothelium and reactive forms of oxygen]. / Endotel a reaktívne formy kyslíka.

Recent experimental findings suggest that we should now consider some diseases as "endotheliopathies" and some others as "ROS-pathies". The presented review summarizes our knowledge on the role of endothelium and reactive oxygen species (ROS) in physiological processes and diseases. The vascular endothelium provides vital and responsive infrastructure of vessels for the circulation of blood and homeostasis of all organs. Due to its exposure to mechanical, chemical and biological factors, including ROS and the nature of its responses to these insults, it is involved in a wide variety of disease processes. Oxidative stress occurs also in many human diseases. Our understanding of the role played by the endothelium and ROS in disease pathology are still insufficient. To determine if endothelial and ROS-induced changes in hypertension, atherosclerosis, ischemia/reperfusion etc. are the primary cause of specific diseases or merely secondary effects remains to be clarified in several areas from inflammatory processes to cardiovascular diseases. Protection of the endothelium and antioxidant therapy represents a potential successful therapeutic approach in different diseases. In the near future the endothelial and free radical research will surely clarify many of our still unanswered questions.

Comparison of antioxidant properties of nifedipine and illuminated nifedipine with nitroso spin traps in low density lipoproteins and phosphatidylcholine liposomes.

Illumination nifedipine, a calcium channel blocker, gives a nitroso-compound, 2,6-dimethyl-4-(2-nitrosophenyl)-3,5-pyridine-dicarboxylic acid dimethyl ester (NTP), which has spin trapping properties. The antioxidant ability of NTP was tested in a model of lipid peroxidation in low density lipoproteins (LDL) and phosphatidylcholine liposomes, and was compared with parent nifedipine and with other nitroso spin traps such as 3,5-dibromo-4-nitrosobenzene-sulfonic acid (BNTB), nitrosobenzene (NTB) and 2-methyl-2-nitrosopropane (MNP). Nifedipine (20-200 mumol/l) did not inhibit lipid peroxidation either in LDL on in liposomes, whereas its photolytical product NTP was found to be very effective at the same concentrations. The average antioxidant potencies of the nitroso spin traps were similar in both models and decreased in the order: NTP > or = BNTB > NTB > or = MNP. As detected by EPR spectroscopy, the studied nitroso compounds formed stable nitroxide radicals in a pseudo-Diels-Alder reaction, as a result of their interaction with unsaturated bonds of lipids in LDL and liposomes. The relative concentrations of thus formed radicals were in the order: NTP >> BNTB >> NTB approximately MNP and were related to their antioxidant properties. Thus it seems that the ability of the nitroso-compounds to form nitroxide radicals with unsaturated lipids may play a role in the antioxidant effect of these compounds.

An unusual temperature dependence of malondialdehyde formation in Fe2+/H2O2-initiated lipid peroxidation of phosphatidylcholine liposomes.

Determination of malondialdehyde is a widely used procedure for measurement of lipid peroxidation. In this paper we report an unusual temperature dependence of malondialdehyde formation in egg yolk phosphatidylcholine liposomes oxidized by the Fenton system (0.1 mmol/l FeSO4 and 0.05 mmol/l H2O2). The amount of malondialdehyde formed was 37% higher in samples kept at 22 degrees C than at 50 degrees C. An alternative method for determination of lipid peroxidation, measurement of oxygen uptake, revealed complete consumption of dissolved oxygen to peroxidized lipids at 22 degrees C as well as 50 degrees C. Since oxygen is essential for the formation of cyclic peroxides--precursors of malondialdehyde--we conclude that the nature of the observed effect consists in limitation of oxygen availability at elevated temperatures.

Incorporation of amphotericin B(Fungizone) in rat brain total lipid liposomes markedly decreases its i.v. toxicity in mice.

Toxicity of the clinically utilized formulation of amphotericin B (1; Fungizone) incorporated in different lipid liposomes was compared in mice. The relative toxicity of i.v. administration of 67 mg Fungizone/kg (30 mg 1/kg), was in the order: Fungizone > Fungizone in phosphatidylcholine liposomes > Fungizone in phosphatidylcholine/cholesterol liposomes > Fungizone in rat brain total lipid liposomes. The survival time of the mice after administration of Fungizone and of Fungizone in total lipid liposomes was less than 1 min and over 30 d, respectively. Using EPR spectroscopy of spin probes a relation between dynamics and disorder of the Fungizone liposomes and their toxicity was observed.

[Antioxidative properties of cardioactive agents]. / Antioxidacné vlastnosti neiktorých kardioaktívnych látok.

Calcium entry blockers reduce the ischemia-reperfusion induced damage to the myocardium. Free oxygen radicals play a role in the pathogenesis of this injury. The mechanism of the protective action of calcium entry blockers is unknown in these conditions and appears to be independent of the blockade of slow calcium channels. As demonstrated in this paper, the calcium entry blockers nifedipine, verapamil and diltiazem are effective scavengers of free oxygen radicals and this characteristic may be importantly involved in their protective effect against myocardial damage induced by ischemia and reperfusion. The pro-oxidative capacity of the antineoplastic drug cisplatin is assumed to play a role in the mechanism of its renal toxicity action. The presented study showed that the new antioxidative substance with antiarrhythmic and antihypoxic properties-stobadine-succeeded in inhibiting the pro-oxidative effect of cisplatin. Our findings suggest that administration of cisplatin along with antioxidants may result in a protective effect against the renal toxicity of cisplatin. (Fig. 5, Ref. 38.)

Formation of stable free radicals from kampo medicines TJ-9, TJ-15, TJ-23, TJ-96, TJ-114 and their antioxidant effect on low density lipoproteins.

The Japanese herbal Kampo medicines TJ-9 (A), TJ-15 (B), TJ-23 (C), TJ-114 (D) and TJ-96 (E) were effective (2-5x less than alpha-tocopherol) in inhibiting a copper-induced peroxidation of low density lipoprotein. Kampo medicines dissolved in n-butanol formed stable free radical(s), detected by EPR spectroscopy as a single asymmetric line with g-value g = 2.005. The radical concentration increased in the order: C less than D approximately A approximately E less than B. When the Kampo medicines were oxidized in n-butanol by excess of PbO2 their radical concentration increased 7-15 fold and was in the order C less than D less than A approximately E much less than B. A relationship between the potency of the medicines to inhibit peroxidation of LDL and their ability to form stable free radicals upon oxidation was observed. The medicine which formed more radicals was more efficient in inhibiting peroxidation of LDL. In order to study whether Kampo medicines can reduce alpha-tocopherol radical, the alpha-tocopherol radical was generated by the reaction of alpha-tocopherol with UV irradiated di-tert-butylperoxide and by autooxidation of alpha-tocopherol in n-butanol (25 microliters ml-1) in air. In both systems vitamin-C greater than Kampo B decreased the concentration of the alpha-tocopherol radical and the EPR spectrum of Kampo B stable radical(s) appeared. The effect of other Kampo medicines was not clearly seen since their EPR spectra were superimposed with the spectrum of the alpha-tocopherol radical. The results indicate that Kampo medicines possess electron donor properties and ability to form stable radical(s). The results may contribute to understanding beneficial effects of Kampo medicines in diseases in which free radical damage is suggested.

Effect of cisplatin, carboplatin and stobadine on lipid peroxidation of kidney homogenate and phosphatidylcholine liposomes.

The effects of the nephrotoxic, anticancer agents cisplatin (CDDP) and carboplatin (CBDCA), and the free radical scavenger, stobadine, were investigated on lipid peroxidation (LPO) of rat kidney homogenates and phosphatidylcholine (PC) liposomes. Kidney homogenates were incubated in air at 37 degrees C for 6-48 h and lipid peroxidation was detected spectroscopically as absorbance (533 nm) of the thiobarbituric acid-malondialdehyde (TBA-MDA) complex. CDDP (0.3-10 mmol.l-1) increased LPO of the homogenate. CBDCA decreased the TBA-MDA absorbance, yet was found to interfere with MDA, TBA and/or with the TBA-MDA complex. Thus when CBDCA is involved, the TBA-MDA method for detection of LPO is not suitable. Stobadine (0.1 mmol.l-1 and 1 mmol.l-1) inhibited LPO either in the control homogenate and in the homogenate where peroxidation was increased by CDDP. The effect of CDDP and CBDCA on peroxidation of PC liposomes was monitored as oxygen consumption using a Clark-type oxygen electrode. CDDP increased but CBDCA decreased the rate of oxygen consumption during the peroxidation of liposomes induced by FeSO4. The results suggest that the effects of CDDP and CBDCA on LPO may be linked with their nephrotoxicity.

Spin-trapping and antioxidant properties of illuminated and nonilluminated nifedipine and nimodipine in heart homogenate and model system.

Nifedipine [1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylic+ ++ acid dimethyl ester] and nimodipine [1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylic+ ++ acid 2-methoxyethyl 1-methylethyl ester], incorporated into diheptanoylphosphatidylcholine liposomes, which were used as a drug carrier system, slightly inhibited lipid peroxidation (induced by tert-butylhydroperoxide and Fe2+) in rat heart homogenate. Illumination of nimodipine had no effect on its antioxidant potency, whereas illuminated nifedipine was several times more effective than nonilluminated drug. On illumination, nifedipine converts to 2,6-dimethyl-4-(2-nitrosophenyl)-3,5-pyridinedicarboxylic acid dimethyl ester (NTP). NTP formed stable radicals when interacting with the rat heart homogenate and dioleoylphosphatidylcholine, as detected by EPR spectroscopy. No radical formation was observed if nonilluminated nifedipine and nimodipine or illuminated nimodipine were used. The spin density of the unpaired electron in the NTP-adduct was centered on the nitrogen derived from its nitroso group. The motion of the NTP-adduct radical was restricted, indicating that the radicals were located in the membrane of the homogenate and not in the buffer system. Only NTP (not nifedipine or nimodipine) was effective in trapping free radicals formed by the thermal or photoinduced decomposition of 2,2'-azobisisobutyronitrile and radicals formed by photolysis of di-tert-butylperoxide. The antioxidant and spin-trapping properties of NTP in our systems were attributed to its nitroso group.

Inhibition of lipid peroxidation of lecithin liposomes kept in a pH-stat system near neutral pH.

During 5 days of autoxidation of egg lecithin liposomes in nonbuffered saline pH dropped from an initial value of 7.4 to 4.5. A linear relationship between oxidation index and pH was obtained. Lipid peroxidation, monitored as conjugated diene and TBA-reactive products, was inhibited significantly by keeping the samples under pH-controlled conditions (7.4 +/- 0.5), compared to controls. Obtained results indicate that the buffering capacity of Tris and Hepes buffers may play a role in their recently reported (D. Fiorentini et al. (1989) Free Radical Res. Commun., 6, 243) inhibitory action against lipid peroxidation of lecithin liposomes.