Action of 21-aminosteroid U74006F as an antioxidant against lipid peroxidation.

The dynamics of the action of the 21-aminosteroid U74006F as an antioxidant against lipid peroxidation were studied in organic solution and membranes. It was confirmed that the reactivities of this compound toward stable phenoxyl radical and peroxyl radical were quite low. In fact, U74006F did not exert appreciable antioxidant effect against the free radical-driven oxidation of methyl linoleate in acetonitrile solution. However, it suppressed the oxidation of phosphatidylcholine liposomal membranes into which it was incorporated in a concentration-dependent manner. The 21-aminosteroid U74006F did not exert any sparing effect on the rate of alpha-tocopherol consumption in the oxidation of methyl linoleate in solution, but when they were simultaneously incorporated into the membrane, U74006F spared alpha-tocopherol and exerted a synergistic effect against the oxidation of liposomal membranes. This suggests that lipophilic U74006F acts as an antioxidant against lipid peroxidation through a physicochemical and not a pure chemical mechanism, and that a physical interaction with the liposomal membrane may facilitate the inhibition of lipid peroxidation with U74006F.

2,3-Dihydro-5-hydroxy-2,2-dipentyl-4,6-di-tert-butylbenzofuran: design and evaluation as a novel radical-scavenging antioxidant against lipid peroxidation.

To develop a novel potent radical-scavenging antioxidant, the ideal structure of a phenolic compound was designed considering the factors that determine antioxidant potency. 2,3-Dihydro-5-hydroxy-2,2-dipentyl-4, 6-di-tert-butylbenzofuran (BO-653) was thus synthesized and its antioxidant activity was evaluated against lipid peroxidations in vitro. The electron spin resonance study showed that the phenoxyl radical derived from BO-653 was more stable than alpha-tocopheroxyl radical. BO-653 reduced alpha-tocopheroxyl radical rapidly, but alpha-tocopherol did not reduce the phenoxyl radical derived from BO-653. However, the chemical reactivity of BO-653 toward peroxyl radical was smaller than that of alpha-tocopherol. This was interpreted as the steric effect of bulky tert-butyl groups at both ortho positions which hindered the access of peroxyl radical to the phenolic hydrogen. However, the tertbutyl substituents increased the stability of BO-653 radical and also lipophilicity, and its antioxidant potency against lipid peroxidation in phosphatidylcholine liposomal membranes was superior to that of alpha-tocopherol. Ascorbic acid reduced the phenoxyl radical derived from BO-653 and spared BO-653 during the oxidation of lipid in the homogeneous solution. On the other hand, ascorbic acid did not spare BO-653 in the oxidation of liposomal membranes. It was concluded that BO-653 is a potent novel radical-scavenging antioxidant.

Effects of solvents and media on the antioxidant activity of alpha-tocopherol.

The effects of solvents and media on the antioxidant activity of alpha-tocopherol were studied. The antioxidant activities of alpha-tocopherol in different solvents decreased in the order of acetonitrile = hexane > ethanol = methanol, which indicates that the antioxidant activity of alpha-tocopherol is smaller in protic solvent than in aprotic solvent. The antioxidant activity of 2-(4,8,12-trimethyltridecyl)-5-hydroxy-2,4,6,7-tetramethylindan , which has similar structure to alpha-tocopherol but does not have ether oxygen, was also measured in protic and aprotic solvents. Its antioxidant activity was smaller than that of alpha-tocopherol in every solvent, but interestingly, substantially the same solvent effects were observed. These results show that the hydrogen bonding between the protic solvent and either oxygen is not important but that the hydrogen binding between protic solvent and phenolic group reduces the activity of alpha-tocopherol. Antioxidant activities of alpha-tocopherol in micelle system and liposomal membrane were markedly reduced compared with that in homogeneous solution. Solvent effect on the alpha-tocopheroxyl radical was also studied by using electron spin resonance. The hyperfine splitting constants of a5CH3H and a7CH3H were smaller in protic solvent than in aprotic solvent, which shows that lone-pair orbital energy on 5-CH3 and 7-CH3 is smaller in protic solvent. The ESR spectra of alpha-tocopheroxyl radical in liposomal membrane and micelle were similar to those observed in aprotic solvent and in protic solvent, respectively, suggesting that alpha-tocopheroxyl radical is located predominantly in the lipophilic domain of the liposomal membrane but in or closer to water phase of micelle aqueous suspensions.

Antioxidant activities of probucol against lipid peroxidations.

The antioxidant activities of probucol were measured in the oxidations of methyl linoleate in homogeneous solution and soybean phosphatidylcholine liposomal membranes and also of low-density lipoproteins. When an excess amount of probucol was reacted with galvinoxyl, the EPR spectrum of galvinoxyl disappeared and a new triplet EPR signal was found: g = 2.0058 and aH(2H) = 0.14 mT. The identical EPR spectrum was observed when probucol was reacted with tert-butoxyl radical generated from di-tert-butylperoxy oxalate. This EPR signal disappeared rapidly when reacted with either alpha-tocopherol or 6-O-palmitoyl-ascorbic acid. Probucol suppressed the free-radical-mediated oxidations of methyl linoleate in hexane and in acetonitrile, in a dose-dependent manner. Its antioxidant activity was 17.5-fold less than that of alpha-tocopherol in hexane. Probucol incorporated into soybean phosphatidylcholine liposomes suppressed its oxidation. The antioxidant activity of probucol was less than that of alpha-tocopherol, but the difference between the two antioxidant activities was smaller in the membranes than in homogeneous solution. Probucol also suppressed the oxidation of low-density lipoprotein. Interestingly, probucol suppressed the oxidation of LDL as efficiently as alpha-tocopherol, implying that physical factors as well as chemical reactivity are important in determining the overall activity of antioxidant in low-density lipoprotein.

Membrane damage due to lipid oxidation.

The influence of free radical-mediated oxidations is amplified because it proceeds by a chain mechanism, ie, only one radical can initiate chain reaction which may propagate over and over again. It was found that the in vitro oxidations of erythrocyte membranes proceed by a chain mechanism with a long kinetic chain length. Thus, the role of chain-breaking antioxidants is quite important, since they scavenge chain-carrying radicals to break a chain reaction. In fact, it has been found experimentally that vitamin E, a lipophilic chain-breaking antioxidant present within the membranes, suppresses the oxidative damage of the membranes more efficiently than water-soluble chain-breaking antioxidants such as vitamin C, which scavenges aqueous radicals but can not scavenge chain-carrying radicals within the membranes.

Antioxidant activity of ubiquinol in solution and phosphatidylcholine liposome.

The antioxidant activities of ubiquinol and ubiquinone were measured in the free radical-mediated oxidations of methyl linoleate in solution and phosphatidylcholine liposomes in aqueous dispersion. Ubiquinol-10 suppressed the oxidation of methyl linoleate in hexane, although its reactivity toward peroxyl radical was about 10 times less than that of alpha-tocopherol. Ubiquinone-10, on the contrary, did not show any antioxidant activity. On the other hand, ubiquinol-10 inhibited the oxidation of phosphatidylcholine liposomal membranes as efficiently as alpha-tocopherol. When both ubiquinol-10 and alpha-tocopherol were present, ubiquinol-10 decreased first and alpha-tocopherol decreased after all ubiquinol-10 was consumed in both solution and liposomes. These results and electron spin resonance (ESR) study suggest that ubiquinol-10 regenerates alpha-tocopherol by reducing alpha-tocopheroxyl radical.

Hemolysis of rabbit erythrocytes induced by cigarette smoke.

Cigarette smoke has been found to induce the hemolysis of rabbit erythrocytes. The particulate phase had more profound effect than the gas phase. Neither free radical scavengers such as ascorbic acid, uric acid and water-soluble vitamin E analogue nor antioxidant enzymes such as catalase and superoxide dismutase suppressed the cigarette smoke-induced hemolysis, suggesting that free radicals, hydrogen peroxide, and superoxide were not the active species.

Oxidative hemolysis of erythrocytes and its inhibition by free radical scavengers.

The oxidative hemolysis of rabbit erythrocytes induced by free radicals and its inhibition by chain-breaking antioxidants have been studied. The free radicals were generated from either a water-soluble or a lipid-soluble azo compound which, upon its thermal decomposition, gave carbon radicals that reacted with oxygen immediately to give peroxyl radicals. The radicals generated in the aqueous phase from a water-soluble azo compound induced hemolysis in air, but little hemolysis was observed in the absence of oxygen. Water-soluble chain-breaking antioxidants, such as ascorbic acid, uric acid, and water-soluble chromanol, suppressed the hemolysis dose dependently. Vitamin E in the erythrocyte membranes was also effective in suppressing the hemolysis. 2,2,5,7,8-Pentamethyl-6-chromanol, a vitamin E analogue without phytyl side chain, incorporated into dimyristoylphosphatidylcholine liposomes, suppressed the above hemolysis, but alpha-tocopherol did not suppress the hemolysis. Soybean phosphatidylcholine liposomes also induced hemolysis, and a lipid-soluble azo initiator incorporated into the soybean phosphatidylcholine liposomes accelerated the hemolysis. The chain-breaking antioxidants incorporated into the liposomes were also effective in suppressing this hemolysis.

Oxidation of lipids. XV. Role of hydrophilic diarylamines as antioxidants in the oxidations of lipids and biological tissues.

The abilities of two kinds of water-soluble diarylamines, disodium 4-chloro-2,2'-iminodibenzoate (CCA) and disodium 4-chloro-3',6'-dimethyl-2,2'-iminodibenzoate (CCM), to protect lipids, membranes and biological tissues from oxidative damages have been studied. The experimental systems studied include the oxidations of methyl linoleate micelles and soybean phosphatidylcholine (Pc) liposomal membranes in aqueous dispersions, oxidative hemolysis of rabbit erythrocytes, and the in vivo oxidative damages of biological tissues all induced by free radicals generated from an azo radical initiator. The two diarylamines functioned as moderate chain-breaking antioxidants and retarded the above oxidations.

Analysis of a case of generalized amniotic fluid embolism by demonstrating the fetal isoantigen (A blood type) in maternal tissues of B blood type, using immunoperoxidase staining.

A case of generalized amniotic fluid embolism, confirmed by staining fetal isoantigen in the maternal tissues, is reported. The distribution of emboli may be more accurately evaluated with the immunochemical staining technic than with standard hematoxylin and eosin stain. The severity of the embolic state is evaluated very exactly.

[Reproduction study on netilmicin. (1) Teratological study in rats (author's transl)].

Teratological study on netilmicin (NTL), a new aminoglycoside antibiotic, was carried out in Sprague-Dawley rats (Slc : SD). NTL was administered intramuscularly to female rats from day 7 to day 17 of gestation at the dosages of 12.5, 25, 50 and 100 mg/kg. The decrease of food intake at the dosage of 50 mg/kg and more, and the resultant depression of maternal body weight gain at the dosage of 100 mg/kg were observed in dams receiving NTL. The depression of fetal growth, such as body weight and ossification of the sternebrae and caudal vertebrae, were detected in animals treated with 50 and 100 mg/kg of NTL. However, NTL failed to induce the external, visceral and skeletal anomalies in fetuses. Also, NTL did not cause any significant changes in birth rate, suckling rate, weaning rate, body weight, postnatal development, behavior and reproductive performance in F1. These results suggest that NTL has no adverse effect on rat fetuses and F1 generation at the dosage of 25 mg/kg or less.

The significance of drug analysis of sweat in respect to rapid screening for drug abuse.

Morphine and methamphetamine, which are excreted in the sweat, are detected by the use of routine serological and physicochemical techniques for urinary examinations. Screening for drug abuse can be done with the same accuracy of that of urine. Rapid excretion of the drug via kidney (within one day) is followed by a slow but steady excretion of the sweat gland. Methamphetamine given orally in a dose of 10 mg is excreted in the sweat at a constant rate (1.4 microgram/ml). No significant difference of the amount excreted by both systems is found. Alveolar lining seems to prevent the elimination of the volatile methamphetamine via respiration. Not only narcotics and stimulants, but also many alkaloids and barbituarates are excreted in the sweat and detected quantitatively by the same principles. The toxicological analysis of the sweat promises a new scope of forensic investigation.