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At least 19 recordsLinked to original sources
PubMedDate not supplied

Reactivity of cysteine S-conjugate sulfoxides: formation of S-[1-chloro-2-(S-glutathionyl)vinyl]-L-cysteine sulfoxide by the reaction of S-(1,2-dichlorovinyl)-L-cysteine sulfoxide with glutathione.

S-(1,2-Dichlorovinyl)-L-cysteine (DCVC) sulfoxide, a putative metabolite of the toxic cysteine S-conjugate DCVC, was synthesized by the reaction of DCVC with H2O2 and characterized by fast atom bombardment mass spectrometry (FAB-MS) and proton nuclear magnetic resonance spectroscopy. DCVC sulfoxide was stable when kept at room temperature overnight in phosphate buffer (pH 6.8-7.8) or when heated in phosphate buffer (pH 7.2 or 7.6) or H2O (pH 3.5 or 10.5) for 20 min at 37 degrees C. However, in the presence of glutathione (GSH), DCVC sulfoxide was readily converted to S-[1-chloro-2-(S-glutathionyl)vinyl]-L-cysteine sulfoxide (I), a product formed by the Michael addition of GSH to DCVC sulfoxide followed by the loss of HCl. Evidence for the mechanism of this reaction was obtained by the finding that DCVC, which cannot act as a Michael acceptor, did not react with GSH under conditions similar to those used with DCVC sulfoxide. When the reaction of DCVC sulfoxide with GSH was carried out at room temperature and pH 7.4, formation of I was complete at 5 min, but when the reaction was carried out for 2 h at pH 6.0 or 4.4 at 37 degrees C, product formation was nearly 37 or 3% of that formed at pH 7.4, respectively; product formation did not increase when the reaction was carried out at pH 8.5. When DCVC sulfoxide (100 mg/kg) was administered to rats, hepatic and renal reduced nonprotein thiol concentrations were decreased at 1 h to 74 and 27% of that in control rats, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Metabolism of diphenyl sulfoxide in perfused guinea pig liver. Involvement of aldehyde oxidase as a sulfoxide reductase.

To evaluate the metabolic capacity of intact guinea pig liver under normoxic and hypoxic conditions, oxidative and reductive metabolism of diphenyl sulfoxide (DPSO) was studied by the nonrecirculating perfusion method in situ. DPSO was exclusively converted into diphenyl sulfone (DPSO2), an oxidative metabolite, under normoxia. When diphenyl sulfide (DPS) was infused, DPSO was eliminated as a predominant metabolite. Judging from the susceptibility toward selective inhibitors of cytochrome P-450, both oxidative steps appear to be catalyzed by cytochrome P-450-dependent monooxygenase rather than flavin adenine dinucleotide-containing monooxygenase. Under hypoxic conditions, however, DPSO2 formation was decreased in parallel with reduced oxygen concentration in the influent perfusate, whereas only a trace amount of DPS, a reductive metabolite, was detected. On the other hand, coinfusion of an electron donor for aldehyde oxidase such as 2-hydroxypyrimidine and benzaldehyde, but not xanthine, markedly stimulated the formation of DPS during hypoxia. These results indicate that the oxidative pathway catalyzed by cytochrome P-450-dependent monooxygenase is predominant in DPSO metabolism under normoxic conditions, whereas only under hypoxia does the reductive pathway become the major one if an electron donor for aldehyde oxidase exists in intact guinea pig liver.

Aldehyde Oxidase↗
PubMed1988

Synergistic cytotoxicity between dimethyl sulfoxide and antineoplastic agents against ovarian cancer in vitro.

Dimethyl sulfoxide is a well-known differentiating agent that has been shown to inhibit tumor growth in vitro. We hypothesized that antineoplastic agents might show synergistic cytotoxicity when combined with 10% dimethyl sulfoxide. Twenty-four malignant ovarian tumors were removed and used in tests to determine the cytotoxicities of 10% dimethyl sulfoxide alone, each of six antineoplastic agents alone, and 10% dimethyl sulfoxide plus each antineoplastic agent. Cytotoxicity results for 10% dimethyl sulfoxide alone and each antineoplastic agent alone were used to evaluate each combination of dimethyl sulfoxide and an antineoplastic agent for synergy. There were 14 synergistic responses that were statistically significant at the p less than 0.01 confidence level between 10% dimethyl sulfoxide and an antineoplastic agent against the ovarian tumors. Seven of these responses were significant at the p less than 0.0003 level. This is strong evidence that true synergistic cytotoxicity occurs when an antineoplastic agent is combined with 10% dimethyl sulfoxide. We conclude that intraperitoneal delivery of antineoplastic agents in 10% dimethyl sulfoxide may be useful in the treatment of certain ovarian cancers.

Anthraquinones↗
PubMed1992

Structural changes by sulfoxidation of phenothiazine drugs.

The side-chain conformations of psychoactive phenothiazine drugs in crystals are different from those of biologically inactive ring sulfoxide metabolites. This study examines the potential energies, molecular conformations and electrostatic potentials in chlorpromazine, levomepromazine (methotrimeprazine), their sulfoxide metabolites and methoxypromazine. The purpose of the study was to examine the significance of the different crystal conformations of active and inactive phenothiazine derivatives, and to determine why phenothiazine drugs lose most of their biological activity by sulfoxidation. Quantum mechanics and molecular mechanics calculations demonstrated that conformations with the side chain folded over the ring structure had lowest potential energy in vacuo, both in the drugs and in the sulfoxide metabolites. In the sulfoxides, side chain conformations corresponding to the crystal structure of chlorpromazine sulfoxide were characterized by stronger negative electrostatic potentials around the ring system than in the parent drugs. This may weaken the electrostatic interaction of sulfoxide metabolites with negatively charged domains in dopamine receptors, and cause the sulfoxides to be virtually inactive in dopamine receptor binding and related pharmacological tests.

Antipsychotic Agents↗
PubMed1991

Dimethyl sulfoxide antagonizes hypotensive, metabolic, and pathologic responses induced by endotoxin.

There is evidence that free radical activity may be important in the development of endotoxemia. Dimethyl sulfoxide is a hydroxyl radical scavenger that readily penetrates cell membranes. Using the conscious, instrumented rat this study tests the ability of dimethyl sulfoxide to modify the course of endotoxemia by evaluating cardiovascular, metabolic, and tissue injury parameters for 4 hr after the toxic insult. Treatment with dimethyl sulfoxide (6.5 g/kg; i.p.) evoked significant decreases in cardiac output, stroke volume, and central venous pressure and increases in heart rate, systemic vascular resistance, mean aortic pressure, respiration rate, and concentrations of blood glucose and plasma lactate. Following endotoxin (40 mg/kg, i.v. LD90- 24 hr), dimethyl sulfoxide pretreatment blocked the early hypotensive episode but all other cardiovascular and respiratory responses to endotoxin were essentially unaltered. The pH, PO2, PCO2, and hematocrit were the same for both treated and untreated groups; however, dimethyl sulfoxide prevented the endotoxin-induced hypoglycemia and significantly attenuated the hyperlacticemia at 4 hr. The severe hemorrhagic intestinal pathology characteristic of this model of endotoxemia was not present in the dimethyl-sulfoxide-treated group. From these results we conclude that dimethyl sulfoxide caused significant cardiovascular alterations conducive to impaired systemic blood flow. However, when administered prior to endotoxin, dimethyl sulfoxide induced significant beneficial modifications in the course of endotoxemia despite few improvements in cardiovascular function. The data indicate that the hydroxyl radical may be a mediator of tissue injury in this model of endotoxemia.

Animals↗
PubMed1987

The sulfoxidation of fluphenazine in schizophrenic patients maintained on fluphenazine decanoate.

Highly sensitive radioimmunoassays were applied to study the sulfoxidation of fluphenazine in 30 schizophrenic patients maintained on either 5 mg or 25 mg fluphenazine decanoate by intramuscular injection every 14 days over a period of 6 months. The presence of the sulfoxide metabolite was detected in all but one of the patients, such that 97% of the 340 plasma samples analysed contained the metabolite. Interpatient variations in plasma levels of fluphenazine, fluphenazine sulfoxide, and in drug to metabolite plasma level ratios were several fold higher than the corresponding intrapatient variations at both dosages. There were statistically significant tendencies for mean plasma fluphenazine levels to rise and mean plasma sulfoxide levels to fall over the 6-month period of study among patients on the high dose, consistent with our previously reported observation that it takes 3-6 months to establish a steady state of fluphenazine with this dosage regimen. By contrast, there were no statistically significant changes in mean plasma levels of either fluphenazine or its sulfoxide in patients on the low dose. Nevertheless, there was a significant rise in fluphenazine to fluphenazine sulfoxide mean plasma level ratios in both dosage groups. It is difficult to assess the significance of the changes in the drug to metabolite ratios with time, since there are no kinetic data on the phase II metabolism (conjugation) of fluphenazine or fluphenazine sulfoxide. This study shows that sulfoxidation is an important major pathway in the metabolism of intramuscularly-administered fluphenazine, and implies that metabolic sites other than gut wall are also involved in the process.

Fluphenazine↗
PubMed1987

Biotransformation and pharmacokinetic overview of enoximone and its sulfoxide metabolite.

Enoximone possesses both positive inotropic and vasodilatory activities and may be useful in the treatment of patients with congestive heart failure (CHF). In all animal species investigated (rat, dog, monkey and man), the major urinary metabolite is the sulfide oxidation product (sulfoxide); very little unchanged drug appears in urine. Both in vitro and in vivo animal studies indicate reversibility of the sulfoxidation reaction; therefore, it is presumed that sulfoxidation is reversible in man. In normal healthy subjects, no difference in extent of absorption due to dietary state is observed. In patients with New York Heart Association class III to IV CHF, median terminal disposition half-lives for enoximone and its sulfoxide metabolite are 6.2 to 7.6 hours, respectively. Enoximone and sulfoxide plasma concentrations from high dose intravenous infusion studies in patients with class III to IV CHF were also investigated. The collective data suggest nonlinearity in one or more pharmacokinetic processes, of which one may be saturation of sulfoxidation. No direct relation between enoximone and/or the sulfoxide metabolite plasma concentration and pharmacologic effect has been established.

Absorption↗
PubMed1990

Similarities between the effects of dimethyl sulfoxide and calmodulin on the red blood cell Ca2(+)-ATPase.

The Ca2(+)-ATPase of the erythrocyte plasma membrane can be activated by calmodulin, acidic phospholipids, limited proteolysis and self-association. Recently, it has been shown that different organic solvents increase both the Vmax and the Ca2+ affinity of the enzyme (Benaim, G. and De Meis, L. (1989) FEBS Lett. 244, 484-486). In this report the effects of calmodulin and dimethyl sulfoxide (20%, v/v) on the Ca2(+)-ATPase are compared. Dimethyl sulfoxide also elicits the appearance of the low-affinity binding site, which in this enzyme is strictly dependent on calmodulin. Dimethyl sulfoxide increases the Ca2+ affinity of the enzyme in a manner similar to that observed with the use of calmodulin and of acidic phospholipids. This was tested using both native and partially trypsinized ATPase. When activated by calmodulin the enzyme is inhibited by compound 48/80, trifluoperazine and calmidazolium. When activated by dimethyl sulfoxide the enzyme is still inhibited by calmidazolium but is no longer inhibited by either compound 48/80 or trifluoperazine. Activation of the ATPase promoted by either calmodulin or dimethyl sulfoxide is abolished when the Ca2+ concentration is raised from 10 microM to 2 mM. The effect of dimethyl sulfoxide is also abolished by 20 mM Pi. In the presence of 1 to 10 mM Ca2+ the ATPase catalyzes an ATP in equilibrium Pi exchange. The rate of exchange increases several fold when dimethyl sulfoxide is included in the assay medium.

Adenosine Triphosphate↗
PubMed1988

High incidence of poor sulfoxidation in patients with primary biliary cirrhosis.

An impaired sulfoxidation pathway has been implicated in the pathogenesis of chlorpromazine-induced hepatotoxicity. Since some patients with chronic chlorpromazine-induced cholestasis may have features of primary biliary cirrhosis, we studied the ability to sulfoxidate the amino acid analogue S-carboxymethyl-cysteine in 44 patients with primary biliary cirrhosis and in two control groups--one without liver disease and one with a variety of liver diseases other than primary biliary cirrhosis. Poor sulfoxidation was observed in 84 percent of the patients with primary biliary cirrhosis, as compared with 24 percent of patients with other liver diseases and 22 percent of normal controls (P less than 0.0005 for both comparisons). Poor sulfoxidation did not correlate with the degree of hyperbilirubinemia or histologic severity of liver disease in any of the groups studied. There was an inverse correlation with age only in the patients with primary biliary cirrhosis (r = -0.44, P less than 0.001). Liver transplantation was performed in six of the patients and improved sulfoxidation in five; in the four with primary biliary cirrhosis, sulfoxidation improved from poor to good or intermediate. We conclude that poor sulfoxidation is closely associated with primary biliary cirrhosis but not with the other liver diseases we studied.

Adolescent↗
PubMed1990

Radioprotective effects of dimethyl sulfoxide in golden hamster embryo cells exposed to gamma rays at 77 K. II. Protection from lethal, chromosomal, and DNA damage.

Golden hamster embryo cells were exposed to 137Cs gamma rays in the presence or absence of dimethyl sulfoxide at both 310 and 77 K. Dimethyl sulfoxide gave significant protection against cell killing at both 310 and 77 K. The extent of radioprotection with 1.28 M dimethyl sulfoxide at 77 K was 85-89% of the lethal effects observed in the absence of dimethyl sulfoxide at 310 K; the dose-modifying factor was 5.7. Dimethyl sulfoxide also exerted protected against gamma-ray-induced DNA single-strand breaks and chromosomal aberrations with a maximum protection of 80-100% at a dimethyl sulfoxide concentration of 1.28 M at 77 K. At 77 K, H atoms, ion holes, and electrons can migrate through frozen cells but OH radicals cannot diffuse. Thus the protective effects of dimethyl sulfoxide against cell killing, chromosomal aberrations, and DNA single-strand breaks at 77 K may be due to the scavenging of H atoms or other ions, rather than OH radicals.

Animals↗
PubMed1986

Sulfide and sulfoxide derivatives of substituted benzimidazoles inhibit acid formation in isolated gastric glands by different mechanisms.

The sulfoxide and sulfide forms of three pairs of substituted benzimidazoles, including omeprazole, were investigated using isolated gastric glands and microsomal membranes containing H+,K+-adenosine Triphosphatase (ATPase). The sulfoxides inhibited stimulated aminopyrine (AP) uptake giving IC50 values between 0.47 and 1.1 microM, whereas the sulfides were less potent and showed a greater variation in IC50 values, 9.5 to 170 microM. The decrease in stimulated oxygen consumption induced by the sulfoxides was parallel to their inhibition of AP-uptake, with IC50 values of 0.40 to 3.7 microM, whereas the sulfides were virtually without effect, IC50 greater than 100 microM. The permeable buffers imidazole and 2,6-dimethylpyridine mimiced the effect of the sulfides on both AP accumulation and oxygen consumption. When tested on H+, K+-ATPase, an enzyme suggested to be the proton pump of the gastric mucosa, the sulfoxides inhibited the ATPase activity with IC50 values between 0.25 to 2.8 microM, in contrast to the sulfides, which were without inhibitory action. The sulfoxide-induced inhibition of AP-uptake in gastric glands and H+, K+-ATPase activity was prevented by the addition of beta-mercaptoethanol, whereas the mercaptane was without effect on sulfide-induced inhibition of AP-accumulation. When tested on vesicles containing H+, K+-ATPase, both the sulfide and sulfoxide derivatives dissipated the proton gradient generated by the enzyme, but only the sulfoxide-induced inhibition was prevented by the addition of beta-mercaptoethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1978

Hepatic disposition and biliary excretion of the organic cations thiazinamium and thiazinamium sulfoxide in rats.

The disappearance from plasma and the excretion in bile of the monoquaternary thiazinamium (administered as the iodide) and one of its polar metabolites, thiazinamium sulfoxide (also administered as the iodide), were studied in the rat after intravenous injection to obtain more information on hepatic transport mechanisms for organic cations. Both compounds exhibited an extremely rapid plasma disappearance, partly due to a rapid liver uptake. After injection of thiazinamium iodide and thiazinamium sulfoxide iodide, 36 and 47%, respectively, of the administered dose were excreted in bile during 1 hr. TLC analysis of the bile showed at least two unidentified polar metabolites in addition to thiazinamium sulfoxide and only 3.8% unchanged thiazinamium after administration of thiazinamium iodide. The same metabolites were found after injection of thiazinamium sulfoxide iodide. Urinary excretion and intestinal secretion were 18 and 12%, respectively, for thiazinamium sulfoxide iodide and 27 and 9%, respectively, of the dose for thiazinamium iodide. It is concluded that, in spite of unequal physicochemical features, thiazinamium iodide and thiazinamium sulfoxide iodide differ only slightly in hepatic uptake and metabolism.

Animals↗
PubMed1988

A controlled study of dimethyl sulfoxide in interstitial cystitis.

To evaluate the effectiveness of dimethyl sulfoxide in the treatment of patients with biopsies suggestive of interstitial cystitis, 33 patients underwent a controlled crossover trial. Patients were allocated randomly to receive 50 per cent dimethyl sulfoxide or placebo (saline). The medication was administered intravesically every 2 weeks for 2 sessions of 4 treatments each. Response was assessed urodynamically and symptomatically. Thirty women and 3 men (mean age 48 years and mean duration of symptoms 5.5 years) were entered into the study. No significant side effects to dimethyl sulfoxide were noted. When assessed subjectively, 53 per cent of dimethyl sulfoxide treated patients were markedly improved compared to 18 per cent of the placebo treated patients. Of the dimethyl sulfoxide group 93 per cent had objective improvement versus 35 per cent of the placebo group. Thus, dimethyl sulfoxide proved to be superior to placebo in the objective and subjective improvement of patients with interstitial cystitis.

Administration, Intravesical↗
PubMed1987

Stimulation of plasminogen activator production by dimethyl sulfoxide in Chinese hamster ovary cells.

The production of plasminogen activator activity in an auxotrophic mutant of the Chinese hamster ovary cell line was found be greatly stimulated by low concentrations of dimethyl sulfoxide. The production of both cell-associated and excreted plasminogen activator activities was stimulated maximally by dimethyl sulfoxide at a concentration of 2.5%. The stimulation of plasminogen activator activity production was found to be completely inhibited by actinomycin D and cycloheximide but not by mitomycin C, implying that new protein and RNA syntheses were required for this process. Using specific antibodies against plasminogen activator, the presence of a tissue-type plasminogen activator could only be detected in dimethyl sulfoxide treated cells. The dimethyl sulfoxide induced plasminogen activator production was observed only in a mutant auxotrophic for adenosine, glycine, and thymidine but not in wild-type cells. The ability of dimethyl sulfoxide to induce the synthesis of plasminogen activator was lost when the cells were hybridized with another complementary auxotrophic mutant. This implies that the ability of dimethyl sulfoxide to stimulate the production of plasminogen activator may be related to the auxotrophic mutation in this cell.

Animals↗