- Biocatalytic synthesis of diaryl disulphides and their bio-evaluation as potent inhibitors of drug-resistant Staphylococcus aureus
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Staphylococcus aureus is a WHO Priority II pathogen for its capability to cause acute to chronic infections and to resist antibiotics, thus severely impacting healthcare systems worldwide. In this context, it is urgently desired to discover novel molecules to thwart the continuing emergence of antimicrobial resistance. Disulphide containing small molecules has gained prominence as antibacterials. As their conventional synthesis requires tedious synthetic procedure and sometimes toxic reagents, a green and environmentally benign protocol for their synthesis has been developed through which a series of molecules were obtained and evaluated for antibacterial activity against ESKAPE pathogen panel. The hit compound was tested for cytotoxicity against Vero cells to determine its selectivity index and time-kill kinetics was determined. The activity of hit was determined against a panel of S. aureus multi-drug resistant clinical isolates. Also, its ability to synergize with FDA approved drugs was tested as was its ability to reduce biofilm. We identified bis(2-bromophenyl) disulphide (2t) as possessing equipotent antimicrobial activity against S. aureus including MRSA and VRSA strains. Further, 2t exhibited a selectivity index of 25 with concentration-dependent bactericidal activity, synergized with all drugs tested and significantly reduced preformed biofilm. Taken together, 2t exhibits all properties to be positioned as novel scaffold for anti-staphylococcal therapy.
- Saima,Soni, Isha,Lavekar, Aditya G.,Shukla, Manjulika,Equbal, Danish,Sinha, Arun K.,Chopra, Sidharth
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p. 171 - 178
(2019/01/04)
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- Bovine serum albumin triggered waste-free aerobic oxidative coupling of thiols into disulphides on water: An extended synthesis of bioactive dithiobis(phenylene)bis(benzylideneimine) via sequential oxidative coupling-condensation reactions in one pot from aminothiophenol and benzaldehyde
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Bovine serum albumin (BSA) has been explored for aerobic oxidative coupling of thiols (aromatic, heterocyclic as well as aliphatic) "on water" towards formation of disulphides (SS) without using any metal/non-metal complexes, bases and additives, which renders the process environmentally benign and economically attractive with good recyclability (up to four cycles). The developed green protocol was further extended for synthesis of diallyldisulphide (DADS), an important constituent of natural occurring allicin. Among various synthesized disulphides, bis(2-aminophenyl)disulphide, obtained by oxidative coupling of 2-aminothiophenol in BSA, was further utilized for condensation with benzaldehyde in the same pot thus enabling easy access to bioactive dithiobis(phenylene)bis(benzyldeneimine). This is the first example of BSA catalysed sequential (oxidation/condensation) reaction where one SS and two CN bonds are formed solely "on water."
- Saima,Lavekar, Aditya G.,Kumar, Rajesh,Sinha, Arun K.
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p. 113 - 123
(2015/04/14)
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- Low-salt or salt-free microbicidal composition based on isothiazolone derivatives and pyrion disulphide
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The present invention relates to a low-salt or salt-free microbicidal preparation which comprises a) at least one fungicide selected from amongst isothiazolone derivatives and b) at least one stabilizer, where the at least one stabilizer is 2,2'-dithiobis(pyridine N-oxide). The microbicidal composition according to the invention is particularly suitable for the preservation of industrial products. The invention also relates to the use of 2,2'-dithiobis(pyridine N-oxide) as stabilizer in low-salt or salt-free isothiazolone-containing microbicidal preparations.
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Page/Page column 7
(2008/06/13)
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- Laser flash photolysis of 2,2′-dithiobis(pyridine N-oxide): Reactivity of N-oxypyridyl-2-thio radical
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Reaction kinetics of radicals produced by the nanosecond laser flash photolysis of 2,2′-dithiobis(pyridine N-oxide) and related compounds have been studied. The transient absorption band at 360 nm was attributed to the radical in which the unpaired electron mainly localizes on the S atom (N-oxypyridyl-2-thio radical). The reactivities of the radical for conjugated dienes are lower than those of the pyridyl-2-thio radical, suggesting that a considerable unpaired electron density on the S atom delocalizes onto the N-oxypyridine moiety. The addition reaction rate of the radical to the conjugating diene was accelerated with hydrogen-bonding solvents and with addition of the cation, which may stabilize the N+-O- canonical structure, increasing the unpaired electron density on the S atom. By the photolysis of N-hydroxypyridine-2-thione, the N-O bond was predominantly dissociated producing a pyridy1-2-thio radical. By the photolysis of its anion, photoejection took place followed by the N-O bond fission, yielding pyridine-2-thione.
- Alam, Maksudul M.,Watanabe, Akira,Ito, Osamu
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- A facile preparation method for α,α-difluoroalkanecarboxylic acids and esters. A formal difluoromethylene insertion to alkanecarboxylic acids using radical reaction
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Various alkyl radicals generated by the photoreaction of a series of Barton esters reacted with 1,1-dichloro-2,2-difluoroethene to give radical adducts as the major product accompanied with self-trapping products. Primary, secondary, tertiary, benzyl, and some unsaturated alkyl radicals as well as those with another functional group such as ether, carbonyl, and azide were applicable. Barton esters of diacids also afford 1:2 adducts with a small amount of 1:1 adducts and bis-self-trapping products except for the succinic case. These adducts were hydrolyzed with AgNO3/H2O-THF to α,α-difluoroalkanecarboxylic acids and methanolyzed with AgNO3/MeOH to the corresponding methyl esters. 4-Azido-2,2-difluorobutylic acid and the methyl ester were converted to difluoro-GABA and difluoro-γ-lactams.
- Okano, Takashi,Takakura, Nobuyuki,Nakano, Yuko,Okajima, Asako,Eguchi, Shoji
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p. 1903 - 1920
(2007/10/02)
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- Generation of hydroxyl radicals from 1-hydroxypyridine-2(1H)-thione and their application to organic synthesis
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Upon irradiation with visible light N-hydroxypyridine-2-thione 1 gives rise to hydroxyl radicals which can be used in radical chain reactions involving selective hydrogen abstraction as the key-step. Key Words: N-hydroxypyridine-2-thione / hydroxyl radicals
- Boivin, J.,Crepon, E.,Zard, S. Z.
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p. 145 - 150
(2007/10/02)
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- Synthesis of Disulfides via Sulfenylation of Alkyl and Aryldithiopyridine N-Oxides
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Alkyl and aryldithiopyridine N-oxides were prepared by reaction of 2,2'-dithiopyridine-1,1'-dioxide with various thiols in high yields.Some of the mixed disulfide products could in turn be used to sulfenylate efficiently other thiols.Therefore, practical and efficient synthetic methods for both symmetrical and unsymmetrical disulfides were developed.
- Barton, Derek H. R.,Chen, Chen,Wall, G. Michael
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p. 6127 - 6138
(2007/10/02)
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- THE GENERATION AND REACTIVITY OF OXYGEN CENTERED RADICALS FROM THE PHOTOLYSIS OF DERIVATIVES OF N-HYDROXY-2-THIOPYRIDONE
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Oxgen centered radicals, formed by the photolysis of derivatives of N-hydroxy-2-thiopyridone, have been trapped by vinyl ethers.In the case of the benzoyloxy radical, smooth deoxygenation is effected by IIIP compounds.Evidence for the formation of the dimethyltbutylsilyloxy and of the hydroxy radical is also presented.
- Barton, Derek H. R.,Jaszberenyi, Joseph Cs.,Morrell, Andrew I.
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p. 311 - 314
(2007/10/02)
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- N-HYDROXY-2-PYRIDINETHIONE: A MILD AND CONVENIENT SOURCE OF HYDROXYL RADICALS
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N-Hydroxy-2-thiopyridone gives hydroxyl radicals on irradiationm with visible light and these can be incorporated in useful radical chain processes involving hydrogen abstraction.
- Boivin, Jean,Crepon, Elisabeth,Zard, Samir Z.
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p. 6869 - 6872
(2007/10/02)
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- SYNTHESIS OF NEW THIOSULFONATES AND DISULFIDES FROM SULFONYL CHLORIDES AND THIOLS
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Aromatic thiols were converted into thiosulfonates or disulfides, under very mild conditions, with fair to excellent yields, by using sulfonyl chloride as oxydant reagent.
- Mahieu, Jean-Pierre,Gosselet, Martine,Sebille, Bernard,Beuzard, Yves
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p. 1709 - 1722
(2007/10/02)
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- Preparation of bis-2-pyridyl-disulfides
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In a process for the preparation of bis-2-pyridyl-disulfide or bis-(2-pyridyl-1-oxide)-disulfide optionally substituted on the pyridyl ring with at least one substituent selected from the group consisting of halogen and alkyl and alkoxy of 1 to 4 carbon atoms by oxidation of the corresponding 2-mercapto-pyridine or its N-oxide, the improvement comprising effecting the oxidation in an aqueous acid media containing an alkali metal or alkaline earth metal chlorite.
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