Cell cycle-dependent disruption of microtubules by methyl jasmonate in tobacco BY-2 cells

Summary Methyl jasmonate, a growth-regulating substance that is ubiquitous in the plant kingdom, was found to disrupt cortical microtubules in tobacco cultured cells. It exerted a microtubule-disrupting effect only in cells at the S phase of the cell cycle. Neither microtubules in preprophase bands, spindles and phragmoplasts nor cortical microtubules at stages of the cell cycle other than the S phase were disrupted by methyl jasmonate. Jasmonic acid was as effective as methyl jasmonate in disrupting cortical microtubules.Abbreviations BUdR 5-bromo-2-deoxyuridine - 2,4-D 2,4-dichlorophenoxyacetic acid - DMSO dimethyl sulfoxide - EGTA ethylene glycol bis(2-aminoethyl ether)-tetraacetic acid - FITC fluorescein isothiocyanate - FUdR 5-fluoro-2-deoxyuridine - JA jasmonic acid - JA-Me methyl jasmonate - PBS phosphate-buffered saline - PMSF phenylmethylsulfonyl fluoride     

Spin Trapping of Methyl Radicals by the Acyl Nitroso Compound PH-C (= O)NO Formed in the Photochemical Reaction Between Benzohydroxamic Acid, Dimethyl Sulfoxide and Hydrogen Peroxide. An Epr Study

By the use of EPR spectroscopy, it has been shown that acyl nitroso compounds can act as spin traps for short-lived radicals with the formation of acyl aminoxyl radicals. The reaction was studied for the system benzohydroxamicacid[Ph-C (= O)N(H)] - dimethyl sulfoxide - hydrogen peroxide. The acyl aminoxyl radicals appeared almost immediately when the reaction mixture was irradiated in situ in the EPR cavity with UV light. The trapping reaction involved two photochemical reactions, i.e. the oxidation of the hydroxamic acid to the acyl nitroso compound Ph-C (= O)NO, and the formation of methyl radicals from dimethyl sulfoxide. The EPR spectra are superpositions of the spectra of two species of acyl aminoxyl radicals, i.e. the radicals Ph-C (= O)N(O·)H formed by oxidation of the parent benzohydrox-amic acid, and the radical Ph-C (= O)N(O·)CH₃, formed by trapping of methyl radicals.     

The chemical and enzymatic oxidation of hematohemin IX. Identification of hematobiliverdin IX alpha as the sole product of the enzymatic oxidation

Oxidative cleavage of hematohemin IX in pyridine solution in the presence of ascorbic acid (coupled oxidation), followed by esterification of the products with boron trifluoride/methanol produced the four possible hematobiliverdin dimethyl esters in 11.1% overall yield. Transetherifications took place simultaneously with the esterification reaction and resulted in the formation of the dimethyl ester of hematobiliverdin IX gamma 8a,13a-dimethyl ether (1.8%), the dimethyl ester of hematobiliverdin IX beta 13a,18a-dimethyl ether (1.9%), the dimethyl ester of hematobiliverdin IX delta 8a-monomethyl ether (1.4%), and the dimethyl ester of hematobiliverdin IX alpha 18a-monomethyl ether (0.4%). The latter was the sole product obtained after the enzymatic oxidation of hematohemin with heme oxygenase, after esterification of the reaction product with boron trifluoride/methanol. When the esterification step was omitted hematobiliverdin IX alpha was obtained from the enzymatic oxidation. The structures of the hematobiliverdin derivatives were secured by their NMR and mass spectra data. Saponification of the dimethyl esters afforded the hematobiliverdin methyl ethers, which were excellent substrates of biliverdin reductase and were readily reduced to the corresponding bilirubins. Hematobiliverdin IX alpha was also a good substrate of biliverdin reductase. It is concluded that the enzymatic oxidation of hematohemin IX by heme oxygenase is alpha-selective, while biliverdin reductase shows no selectivity in the reduction of the four hematobiliverdin isomers.     

Catalytic conversion of glucose to 5-hydroxymethyl furfural using inexpensive co-catalysts and solvents

Efficient conversion of glucose to 5-hydroxymethyl furfural (5-HMF), a platform chemical for fuels and materials, was achieved using CrCl₂ or CrCl₃ as the catalysts with inexpensive co-catalysts and solvents including halide salts in dimethyl sulfoxide (DMSO) and several ionic liquids. 5-HMF (54.8%) yield was achieved with the CrCl₂/tetraethyl ammonium chloride system at mild reaction conditions (120 °C and 1 h). The 5-HMF formation reaction was found to be faster in ionic liquids than in the DMSO system. Effects of water in the reaction system, chromium valence and reaction temperature on the conversion of glucose into 5-HMF were discussed in this work.     

Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate

The purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1∶1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2∶1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization from these organic solvents. Structural, spectral, and thermal analysis results confirmed the presence of the solvents and differences in the structural properties of these solvates. In addition, differences in the activation energy of desolvation, batch solution calorimetry, and the aqueous solubility at 25°C, 24 hours, showed the stability of the solvates to be in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > methanol solvate > dimethyl sulfoxide solvate > N,N' dimethylformamide solvate. The intrinsic and powder dissolution rates of the solvates were in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > N,N' dimethylformamide solvate > methanol solvate > dimethyl sulfoxide solvate. Although these nonaqueous solvates had higher solubility and dissolution rates than the monohydrous forms, they were unstable in aqueous media and rapidly transformed to one of the monohydrous forms.     

Bactericidal activity of peroxynitrite.

Peroxynitrite is a strong oxidant formed by macrophages and potentially by other cells that produce nitric oxide and superoxide. Peroxynitrite was highly bactericidal, killing Escherichia coli in direct proportion to its concentration with an LD50 of 250 microM at 37 degrees C in potassium phosphate, pH 7.4. The apparent bactericidal activity of a given concentration peroxynitrite at acidic pH was less than that at neutral and alkaline pH. However, after taking the rapid pH-dependent decomposition of peroxynitrite into account, the rate of the killing was not significantly different at pH 5 compared to pH 7.4. Metal chelators did not decrease peroxynitrite-mediated killing, indicating that exogenous transition metals were not required for toxicity. The hydroxyl radical scavengers mannitol, ethanol, and benzoate did not significantly affect toxicity while dimethyl sulfoxide enhanced peroxynitrite-mediated killing. Dimethyl sulfoxide is a more efficient hydroxyl radical scavenger than the other three scavengers and increased the formation of nitrogen dioxide from peroxynitrite. In the presence of 100 mM dimethyl sulfoxide, 60.0 +/- 0.3 microM nitrogen dioxide was formed from 250 microM peroxynitrite as compared to 2.0 +/- 0.1 microM in buffer alone. Thus, formation of nitrogen dioxide may have enhanced the toxicity of peroxynitrite decomposing in the presence of dimethyl sulfoxide.     

Phosphate-guanosine interactions. A model for the involvement of guanine derivatives in autocatalytic reactions of ribonucleic acids

Proton magnetic resonance was used to study the interactions between nucleosides and phosphate monoanion in dimethyl sulfoxide. Ribose was able to form two mutually exclusive 1:1 complexes involving either OH3' and OH5' or OH3' and OH2' as hydrogen bond donor groups. Deoxyribose could form only one of these complexes. A specific interaction of phosphate with the base moiety of nucleosides was observed only with guanosine. A 1:1 complex was formed involving the N(1)H and NH2(2) of guanine. Association constants for both the base and sugar complexes were determined to be in the range 50-60 M-1 at 21 degrees C in dimethyl sulfoxide. This value is more than 1 order of magnitude higher than that measured for guanine-cytosine base pair formation under the same conditions. Water addition to dimethyl sulfoxide led to a decrease of all association constants but the guanine-phosphate "pair" remained more stable than the guanine-cytosine base pair.     

Quantitation and interaction of glycosaminoglycans with Alcian blue in dimethyl sulfoxide solutions.

An improved method is described for the quantitation of glycosaminoglycans separatedon cellulose acetate, stained with Alcian blue, and dissolved in a dimethyl sulfoxide solution. Standard curves are shown for all eight glycosaminoglycans. It is shown that absorption at the Alcian blue orthochromatic E_max is depressed under conditions which favor formation of dye-glycosaminoglycan complexes. The interaction between Alcian blue and the eight glycosaminoglycans was studied in dimethyl sulfoxide solutions of varying composition. It was shown that the extent of complex formation depends both on the glycosaminoglycan and the composition of the dimethyl sulfoxide solution. A dimethyl sulfoxide solution which contains 0.094 m H₂SO₄ is described which maximizes dye-glycosaminoglycan dissociation and thus the absorbance. Also, an improved staining method is described which improves dye uptake by the glycosaminoglycans and consequently increases the sensitivity of glycosaminoglycan quantitation.     

Oxidation of methyl fluoride and dimethyl ether by ammonia monooxygenase in Nitrosomonas europaea.

Methyl fluoride and dimethyl ether were previously identified as inhibitors of ammonia oxidation and N2O production in autotrophic nitrifying bacteria. We demonstrate that methyl fluoride and dimethyl ether are substrates for ammonia monooxygenase and are converted to formaldehyde and a mixture of methanol and formaldehyde, respectively.     

A convenient method for methylation of glycoprotein glycans in small amounts by using lithium methylsulfinyl carbanion

Treatment of dimethyl sulfoxide with butyllithium leads to rapid formation of lithium methylsulfinyl carbanion. The reaction products tend to be significantly freer from impurities when lithium methylsulfinyl carbanion is used rather than sodium or potassium methylsulfinyl carbanion. This reagent gives less background in g.l.c. and thus may be used to methylate micro-quantities of glycoprotein glycans (down to 10 micrograms) without the necessity of identifying methyl ethers by mass spectrometry.     

Graft copolymerization of methyl methacrylate onto mercaptochitin and some properties of the resulting hybrid materials

The graft copolymerization of methyl methacrylate onto mercaptochitin and some properties of the resulting graft copolymers have been studied. Methyl methacrylate was efficiently graft copolymerized onto mercaptochitin in dimethyl sulfoxide, and the grafting percentage reached 1300% under appropriate conditions. Although the side-chain ester groups were resistant to aqueous alkali, hydrolysis could be achieved with a mixture of aqueous sodium hydroxide and dimethyl sulfoxide. Subsequent treatment with acetic anhydride in methanol transformed the sodium carboxylate groups into carboxyl groups. Although the graft copolymers exhibited an improved affinity for organic solvents, those having sodium carboxylate or carboxyl units were characterized by a much more enhanced solubility and were soluble in common solvents. The hygroscopic nature of chitin decreased with an increase in the grafting extent but increased significantly upon hydrolysis of the ester groups. The enzymatic degradability of the graft copolymers, as evaluated with lysozyme, was also dependent on the grafting extent and much higher than that of the original chitin. DSC measurements revealed the presence of a glass transition phenomenon, which could be ascribed to the poly(methyl methacrylate) side chain.     

Formation of a TBA reaction product from crown ether in the presence of KO2.

Potassium superoxide (KO2), which can be dissolved in dimethyl sulfoxide containing crown ether, has been used as a source of O2-. for superoxide reaction systems. We have found that crown ether reacts with thiobarbituric acid (TBA) in the presence of KO2 to form a red pigment, which is a well-known reaction product of lipoperoxide.     

A new mechanism for the aerobic catabolism of dimethyl sulfide.

Aerobic degradation of dimethyl sulfide (DMS), previously described for thiobacilli and hyphomicrobia, involves catabolism to sulfide via methanethiol (CH3SH). Methyl groups are sequentially eliminated as HCHO by incorporation of O2 catalyzed by DMS monooxygenase and methanethiol oxidase. H2O2 formed during CH3SH oxidation is destroyed by catalase. We recently isolated Thiobacillus strain ASN-1, which grows either aerobically or anaerobically with denitrification on DMS. Comparative experiments with Thiobacillus thioparus T5, which grows only aerobically on DMS, indicate a novel mechanism for aerobic DMS catabolism by Thiobacillus strain ASN-1. Evidence that both organisms initially attacked the methyl group, rather than the sulfur atom, in DMS was their conversion of ethyl methyl sulfide to ethanethiol. HCHO transiently accumulated during the aerobic use of DMS by T. thioparus but not with Thiobacillus strain ASN-1. Catalase levels in cells grown aerobically on DMS were about 100-fold lower in Thiobacillus strain ASN-1 than in T. thioparus T5, suggesting the absence of H2O2 formation during DMS catabolism. Also, aerobic growth of T. thioparus T5 on DMS was blocked by the catalase inhibitor 3-amino-1,2,4-triazole whereas that of Thiobacillus strain ASN-1 was not. Methyl butyl ether, but not CHCl3, blocked DMS catabolism by T. thioparus T5, presumably by inhibiting DMS monooxygenase and perhaps methanethiol oxidase. In contrast, DMS metabolism by Thiobacillus strain ASN-1 was unaffected by methyl butyl ether but inhibited by CHCl3. DMS catabolism by Thiobacillus strain ASN-1 probably involves methyl transfer to a cobalamin carrier and subsequent oxidation as folate-bound intermediates.     

Inhibition of chemically induced erythrodifferentiation in friends erythroleukemia cells by d,1-Propranolol

Dimethyl sulfoxide (2%), hexamethylene bisacetamide (4mM) and butyric acid (2mM) were potent inducers of erythrodifferentiation in Friend erythroleukemia cell lines, 5–18 and C19TK. Hydrocortisone (1μM) markedly inhibited dimethyl sulfoxide induced hemoglobin production in both 5–18 and C19TK cells. d,1-Propranolol (25–50μM) markedly inhibited both dimethyl sulfoxide and hexamethylene bisacetamide induced erythrodifferentiation in 5–18 cells but not in C19TK cells. Addition of either hydrocortisone or propranolol as late as 48 hrs after dimethyl sulfoxide addition still resulted in significant inhibition of hemoglobin synthesis in 5–18 cells. Although the mechanism of action of propranolol is not known, modulation of the β adrenergic receptor is apparently not involved since practolol failed to inhibit either dimethyl sulfoxide or hexamethylene bisacetamide induced erythrodifferentiation in 5–18 cells nor did isoproternol induce hemoglobin synthesis.     

Compatibility of organic solvents with the Salmonella/microsome test

We have screened 14 solvents for compatibility with the Salmonella mutagenicity test and have found 12 to be satisfactory under the conditions specified. These 12 solvents are: dimethyl sulfoxide, glycerol formal, dimethyl formamide, formamide, acetonitrile, 95% ethanol, acetone, ethylene glycol dimethyl ether, 1-methyl-2-pyrrolidinone, p-dioxane, tetrahydrofurfuryl alcohol and tetrahydrofuran.The influence of the nutrient broth culture medium on the spontaneous mutation rate of the tester strains is also discussed.     

Pharmacologic enhancement of rat skin flap survival with topical oleic acid

This study was instituted to investigate in a rat model the effect of topical coadministration of the penetration enhancer oleic acid (10% by volume) and RIMSO-50 (medical grade dimethyl sulfoxide, 50% by volume) on rat skin flap survival. A rectangular abdominal skin flap (2.5 x 3 cm) was surgically elevated over the left abdomen in 40 nude rats. The vein of the flap's neurovascular pedicle was occluded by placement of a microvascular clip, and the flap was resutured with 4-0 Prolene to its adjacent skin. At the end of 8 hours, the distal edge of the flap was reincised to gain access to the clips and the clips were removed. After resuturing of the flap's distal edge to its adjacent skin, the 40 flaps were randomly divided into four groups. Group 1 (control) flaps were treated with 5 g of saline, group 2 (dimethyl sulfoxide) flaps were treated with 2.7 g of dimethyl sulfoxide (50% by volume), group 3 flaps (oleic acid) were topically treated with 0.45 g of oleic acid (10% by volume), and group 4 (dimethyl sulfoxide plus oleic acid) flaps were treated with a mixture of 0.45 g of oleic acid (10% by volume) and 2.7 g of dimethyl sulfoxide (50% by volume) diluted in saline. Each flap was topically treated with 5 ml of drug-soaked gauze for 1 hour immediately after clip removal to attenuate reperfusion injury. Thereafter, drug was applied topically once daily for 4 more days. Digital photographs of each flap were then taken on day 6 and the flaps were then harvested. The percentage of skin survival in each flap was determined by computerized morphometry and planimetry. The mean surviving area of group 3 (oleic acid-treated flaps) was 23.60 +/- 4.19 percent and was statistically higher than that in group 1 (control, saline-treated flaps) at 7.20 +/- 2.56 percent. The mean surviving area of group 2 (dimethyl sulfoxide-treated flaps) at 18.00 +/- 5.23 percent and group 4 (oleic acid- and dimethyl sulfoxide-treated flaps) at 9.90 +/- 3.44 percent did not achieve statistically higher mean surviving areas than controls. A topical solution of oleic acid (10% by volume) caused a statistically significant increase in the survival of rat abdominal skin flaps relative to controls. Dimethyl sulfoxide and the two experimental drugs together did not increase the percentage of flap survival when given as a single 5-ml dose released from a surgical sponge at reperfusion for 1 hour and then daily for a total of 5 days. The reasons for the lack of response are unknown but may have included the technical difficulty of delivering an adequate dose of dimethyl sulfoxide topically and immiscibility between dimethyl sulfoxide and oleic acid. Further studies may be warranted.     

New bile alcohols--synthesis of 5beta-cholestane-3alpha, 7alpha, 25-triol and 5beta-cholestane-3alpha, 7alpha, 25-24 (14C)-triol.

5beta-Cholestane-3alpha, 7alpha, 25-triol and 5beta-cholestane-3alpha, 7alpha, 25-24(14-C)-triol were synthesized from 3alpha, 7alpha-dihydroxy-5beta-cholanoic acid (chenodeoxycholic acid). Chenodeoxycholic acid was converted to the diformoxy derivative (II) using formic acid. Reaction of II with thionyl chloride yielded the acid chloride which was treated with diazomethane (CH-2-N-2 or 14-CH-2-N-2) to produce 3alpha, 7alpha-diformoxy-24-oxo-25-diazo-25-homocholane (III, A or B). 25-Homochenodeoxycholic acid (IV, A or B) was formed from III by means of the Wolff rearrangement of the Arndt-Eistert synthesis. The methyl ester of V (A or B) was treated with methyl magnesium iodidi in ether to provide the desired triol, VI (A and B). The triol was identified by mass spectrometry and elemental analysis and was characterized by thin-layer and gas-liquid chromatography. The 3alpha, 7alpha, 25-triol is of possible significance as an intermediate in the pathway of bile acid formation from cholesterol.     

Selective N-desulfation of heparin with dimethyl sulfoxide containing water or methanol.

A solvolytic N-desulfation of heparin was developed by treatment of its pyridinium salt with dimethyl sulfoxide containing 5% of water or methanol for 1.5 h at 50 degrees. Chemical and chromatographic studies showed that the solvolytic desulfation is a useful method for N-desulfation of heparin without depolymerization of the heparin molecule. The partially N-desulfated heparins were also obtained by treatment with dimethyl sulfoxide containing 5% of water at 20 degrees, and their anticoagulant activity is related to the degree of N-desulfation.     

Catalytic action of L-2-halo acid dehalogenase on long-chain L-2-haloalkanoic acids in organic solvents

A Lyophilized preparation of L-2-halo acid dehalogenase was not only stable but also catalytically active in anhydrous dimethyl sulfoxide, toluene, and other organic solvents. 2-Halo acids with long alkyl (C(5)-C(16)) or aromatic (phenyl and benzyl) side chains were inert in water but dehalogenated effectively in anhydrous dimethyl sulfoxide by the lyophilized enzyme. Long chain 2-haloalkanoic acids such as 2-bromohexadecanoic acids were better as substrate than short-chain halo acids (e.g., 2-chloropropanoic acid). The dehalogenation proceed with inversion of C(2) configuration to produce the corresponding (2R)-2-hydroxy acids in anhydrous dimethyl sulfoxide in the same way as found in water.     

Conformational studies of poly(L-tyrosine). A helix–coil transition in dimethyl sulfoxide–dichloroacetic acid mixtures

Poly(L -tyrosine) is a random coil in dimethyl sulfoxide. Upon addition of dichloroacetic acid, poly(L -tyrosine) undergoes a conformational transition centered at about 10% dichloroacetic acid. The transition is nearly complete at 20% dichloroacetic acid. Further addition of dichloroacetic acid leads to precipitation of poly(L -tyrosine). We have characterized this transition by optical rotation, viscosity, circular dichroism, and infrared. The optical rotation at 350 nm and the intrinsic viscosity increase sharply to values that are consistent with a transition to the α-helix conformation. The circular dichroism of poly(L -tyrosine) in dimethyl sulfoxide and in dimethyl sulfoxide/dichloroacetic acid (80:20 v/v) agrees with previous reports for random-coil and α-helix conformations, respectively. The infrared spectrum of poly(L -tyrosine) in dimethyl sulfoxide/dichloroacetic acid (80:20 v/v) shows no evidence of β-structure. We conclude that the transition on going from dimethyl sulfoxide to 20% dichloroacetic acid in dimethyl sulfoxide is a coil → α-helix transition. The amide-I band of poly(L -tyrosine) in dimethyl sulfoxide/dichloroacetic acid (80:20) is found to be at 1662 cm^?1. It has been suggested that this high frequency may be indicative of a left-handed α-helix. However, this high amide-I frequency is consistent with conformational energy calculations of Scheraga and co-workers. The mechanism of the dichloroacetic acid-induced transition to an α-helix is discussed. Dichloroacetic acid and dimethyl sulfoxide interact strongly and the transition presumably involves a marked decrease in the ability of dimethyl sulfoxide to solvate the peptide backbone and aromatic side chains upon complex formation with dichloroacetic acid.