- Development of antimicrobial laser-induced photodynamic therapy based on ethylcellulose/chitosan nanocomposite with 5,10,15,20-tetrakis(M-hydroxyphenyl)porphyrin
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The development of new antimicrobial strategies that act more efficiently than traditional antibiotics is becoming a necessity to combat multidrug-resistant pathogens. Here we report the effi-cacy of laser-light-irradiated 5,10,15,20-tetrakis(m-hydroxyphenyl)porphyrin (mTHPP) loaded onto an ethylcellulose (EC)/chitosan (Chs) nanocomposite in eradicating multi-drug resistant Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. Surface loading of the ethylcelllose/chitosan composite with mTHPP was carried out and the resulting nanocomposite was fully characterized. The results indicate that the prepared nanocomposite incorporates mTHPP inside, and that the composite acquired an overall positive charge. The incorporation of mTHPP into the nanocomposite enhanced the photo-and thermal stability. Different laser wavelengths (458; 476; 488; 515; 635 nm), powers (5–70 mW), and exposure times (15–45 min) were investigated in the antimicrobial pho-todynamic therapy (aPDT) experiments, with the best inhibition observed using 635 nm with the mTHPP EC/Chs nanocomposite for C. albicans (59 ± 0.21%), P. aeruginosa (71.7 ± 1.72%), and S. aureus (74.2 ± 1.26%) with illumination of only 15 min. Utilization of higher doses (70 mW) for longer periods achieved more eradication of microbial growth.
- Hasanin, Mohamed S.,Abdelraof, Mohamed,Fikry, Mohamed,Shaker, Yasser M.,Sweed, Ayman M. K.,Senge, Mathias O.
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- 3-/4-ester substituted benzaldehyde thiosemicarbazone derivatives as well as preparation and application thereof
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The invention belongs to the technical field of tyrosinase inhibitors, and discloses 3-/4-ester substituted benzaldehyde thiosemicarbazone derivatives as well as preparation and an application thereof. The 3-/4-ester substituted benzaldehyde thiosemicarbazone derivatives have a structural formula represented by a formula I shown in the description, wherein RCOO- is used as a 3-position substituentor 4-position substituent, and R is alkyl, phenyl or benzyl. The 3-/4-ester substituted benzaldehyde thiosemicarbazide derivatives provided by the invention are used as the tyrosinase inhibitors, andused for preparation of a medicine for treating Parkinson syndrome and an anti-melanoma medicine, and preparation of whitening cosmetics, biological insecticides and food preservatives. The 3-/4-ester substituted benzaldehyde thiosemicarbazone derivatives provided by the invention are extremely simply synthesized, and can be obtained only through a simple esterification reaction and a Schiff basereaction; and meanwhile the 3-/4-ester substituted benzaldehyde thiosemicarbazone derivatives provided by the invention have better activity, and have strong inhibitory activity against tyrosinase.
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Paragraph 0027; 0028
(2018/06/28)
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- Synthesis of functionally substituted benzaldehydes
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A new method of synthesis of functionally substituted benzaldehydes by catalytic debromometoxylation of dibromomethylarenes with benzaldehyde dimethyl acetal has been suggested. Anhydrous zinc chloride has been used as a catalyst. Being soft Lewis acid, it formed no strong complex with aldehyde group and other functional groups. The initial acetal has been readily recovered by the treatment of benzaldehyde isolated from the reaction mixture with trimethyl orthoformate.
- Gazizov,Ivanova, S. Yu.,Ibragimov, Sh. N.,Khairullin,Karimova,Gazizova,Antipin
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p. 227 - 229
(2017/11/07)
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- Chemoselective reduction of the carbonyl functionality through hydrosilylation: Integrating click catalysis with hydrosilylation in one pot
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Herein we report the chemoselective reduction of the carbonyl functionality via hydrosilylation using a copper(I) catalyst bearing the abnormal N-heterocyclic carbene 1 with low (0.25 mol %) catalyst loading at ambient temperature in excellent yield within a very short reaction time. The hydrosilylation reaction of α,β-unsaturated carbonyl compounds takes place selectively toward 1,2-addition (C=O) to yield the corresponding allyl alcohols in good yields. Moreover, when two reducible functional groups such as imine and ketone groups are present in the same molecule, this catalyst selectively reduces the ketone functionality. Further, 1 was used in a consecutive fashion by combining the Huisgen cycloaddition and hydrosilylation reactions in one pot, yielding a range of functionalized triazole substituted alcohols in excellent yields.
- Roy, Sudipta Raha,Sau, Samaresh Chandra,Mandal, Swadhin K.
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p. 9150 - 9160
(2014/12/11)
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- Iron (III) phosphate as a green and reusable catalyst promoted chemo selective acetylation of alcohols and phenols with acetic anhydride under solvent free conditions at room temperature
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Iron (III) phosphate was employed as an efficient catalyst for the chemo selective acetylation of alcohols and phenols under solvent free condition at room temperature and with high yields. Iron (III) phosphate is also a potential green catalyst due to solid intrinsically, reusable and with high catalytic activity.
- Behbahani,Farahani,Oskooie
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experimental part
p. 633 - 637
(2011/10/08)
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- Chemical insights in the concept of hybrid drugs: The antitumor effect of nitric oxide-donating aspirin involves a quinone methide but not nitric oxide nor aspirin
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Hybrid drug 1 (NO-ASA) continues to attract intense research from chemists and biologists alike. It consists of ASA and a -ONO2 group connected through a spacer and is in preclinical development as an antitumor drug. We report that, contrary to current beliefs, neither ASA nor NO contributes to this antitumor effect. Rather, an unsubstituted QM was identified as the sole cytotoxic agent. QM forms from 1 after carboxylic ester hydrolysis and, in accordance with the HSAB theory, selectively reacts with cellular GSH, which in turn triggers cell death. Remarkably, a derivative lacking ASA and the -ONO 2 group is 10 times more effective than 1. Thus, our data provide a conclusive molecular mechanism for the antitumor activity of 1. Equally importantly, we show for the first time that a "presumed invisible" linker in a hybrid drug is not so invisible after all and is in fact solely responsible for the biological effect.
- Hulsman, Niels,Medema, Jan Paul,Bos, Carina,Jongejan, Aldo,Leurs, Rob,Smit, Martine J.,De Esch, Iwan J. P.,Richel, Dick,Wijtmans, Maikel
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p. 2424 - 2431
(2008/02/03)
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- Microwave-assisted NiCl2 promoted acylation of alcohols
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A microwave oven acylation of alcohols by carboxylic acid anhydrides has been developed. NiCl2 has been proven an efficient catalyst for the acylation of primary, secondary, and tertiary alcohols and phenols under microwave conditions.
- Constantinou-Kokotou, Violetta,Peristeraki, Anna
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p. 4227 - 4232
(2007/10/03)
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- New Pd-catalyzed selective reduction of carboxylic acids to aldehydes.
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A catalyst generated in situ from palladium acetate and tricyclohexylphosphine efficiently catalyzes the reduction of carboxylic acids with sodium hypophosphite in the presence of pivalic anhydride to give aldehydes with high selectivity. The low cost and convenient handling of the reagents makes this process a valuable alternative to hydrogenations and metal hydride reductions.
- Goossen, Lukas J,Ghosh, Keya
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p. 836 - 837
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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- Synthesis of stable water-soluble chemiluminescent 1,2-dioxetanes and intermediates therefor
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A novel synthesis of compounds having the formula: STR1 wherein T is a stabilizing spiro-linked polycycloalkylidene group, R3 is a C1 -C20 alkyl, aralkyl or heteroatom containing group, Y is an aromatic fluorescent chromophore, and Z is a cleavable group which, when cleaved, induces decomposition of the dioxetane ring and emission of optically detectable light, is disclosed. A tertiary phosphorous acid alkyl ester of the formula: wherein R1 is a lower alkyl group, is reacted with an aryl dialkyl acetal produced by reacting a corresponding aryl aldehyde with an alcohol of the formula: wherein R3 is as defined above, to produce a 1-alkoxy-1-arylmethane phosphonate ester of the formula: STR2 reacting the phosphonate with base to produce a phosphonate-stabilized carbanion, reacting the carbanion with a ketone of the formula: wherein T is as defined above, to produce an enol ether of the formula: STR3 then oxygenating the double bond in the enol ether to give the corresponding 1,2-dioxetane compound.
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- REGIOSELECTIVE METALLATIONS OF (METHOXYMETHOXY)ARENES
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The methoxymethoxy substituent when attached to an aromatic ring functions as a moderately strong ortho-directing group in hydrogen-metal exchenge reactions.In many cases the propensity of the methoxymethoxylated arene toward ring metallations is greatly enhanced with concomitant suppression of undesirable side reactions such as nucleophilic attack and addition of metallating species.Unlike many other ortho-directing groups, the regio-direction of the methoxymethoxy substituent when in conjunction with other weaker directing groups is dependent upon the metallating medium.Thus, by changing the electron donating capacity of the metallating medium it is possible to selectively direct metallation to either of the positions ortho to the methoxymethoxy substituent.
- Ronald, Robert C.,Winkle, Mark R.
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p. 2031 - 2042
(2007/10/02)
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- Regioselective Metalation Reactions of Some Substituted (Methoxymethoxy)arenes
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The methoxymethoxy substituent acts as a relatively strong ortho-directing group in hydrogen-metal exchange reactions.However, the directing effects are influenced by the metalation medium, thus permitting an unusual degree of control of the site of metalation.In conjunction with weak ortho-directing groups, the metalation ortho to the methoxymethoxy group can be directed to either of the ortho positions by controlling the electron-donating capacity of the metalating solvent.In strongly donating solvents the 1,2,4-substitution pattern will arise from a meta-substituted methoxymethoxy arene, while in nondonating solvents the 1,2,3-substitution is favored.In addition, the methoxymethoxy group serves also to enhance the rate of metalation and to stabilize the aryl-metalated products so that some competing addition reactions are supressed.
- Winkle, Mark R.,Ronald, Robert C.
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p. 2101 - 2108
(2007/10/02)
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