Photodegradable Antimicrobial Agents: Synthesis and Mechanism of Degradation.

As a strategy to inactivate antimicrobial agents after use, we designed a range of ethanolamine derivatives where four of them possessed interesting activity. The ethanolamine moiety facilitates photodecomposition, which in a potential drug will take place after use. Herein, the synthetic preparation of these compounds and the mechanism of photoinactivation are described.

Photodegradable antimicrobial agents - synthesis, photodegradation, and biological evaluation.

Multi-drug resistant (MDR) bacteria are already a significant health-care problem and are making the combat of infections quite challenging. Here we report the synthesis of several new compounds containing an ethanolamine moiety, of which two exhibit promising antimicrobial activity (at the 6 µM level). All the compounds are degraded when exposed to light and form inactive products.

Conjugated Ynones in Organic Synthesis.

This review article will consider the preparation and application of ynones in synthetic organic chemistry. Concerning the preparation of these bifunctional compounds, several methodologies starting from propargyl alcohols, acyl derivatives, both by using alkynylmetal reagents or by transition metal (mainly palladium and copper) catalyzed alkynylations, carbon monoxide (carbonylation of terminal alkynes and alkenes), and other substrates will be discussed. The reactivity and synthetic applications of ynones will be focused on conjugate additions with boron-, carbon-, nitrogen-, oxygen-, and other heteroatom-containing nucleophiles, as well as radicals. Then, cycloaddition processes will include [2 + 2] cycloadditions, [3 + 2] 1,3-dipolar cycloadditions (with azides, nitrones, azomethine imines and ylides, nitrile oxides, diazo compounds, and other dipoles), and [4 + 2] cycloadditions (mainly Diels-Alder-type reactions). The reduction of the triple bond, addition to the carbonyl group (using carbon- and heteronucleophiles and reductions), and other not so commonly used processes (such as aldol reactions, cyclizations, and isomerizations) will be considered at the end.

Preparation and Assessment of Self-Immolative Linkers for Therapeutic Bioconjugates with Amino- and Hydroxyl-Containing Cargoes.

A series of self-immolative linkers containing a thiol-reactive group at one end and a hydroxyl- or amine-reactive group at the other were prepared. The utility of these reagents for preparations of bioconjugates was explored by reacting the linkers with appropriately functionalized model drugs and peptides. Degradation studies of a series of conjugates with different linkers reveal that the structure of the linkers has a significant impact on their stability.

Detection of PPCPs in marine organisms from contaminated coastal waters of the Saudi Red Sea.

The occurrence of PPCPs in macroalgae, barnacle and fish samples from contaminated coastal waters of the Saudi Red Sea is reported. Solvent extraction followed by solid phase extraction was applied to isolate the compounds, and their quantification was carried out by high performance liquid chromatography-tandem mass spectrometry. Atenolol, ranitidine, chlorpheniramine, DEET, and atrazine were detected in one or more macroalgae at

Synthesis and reactivity of 4-amino-substituted furfurals.

γ-Hydroxy α,ß-unsaturated acetylenic ketones have been converted to 4-amino-substituted furfurals by reaction with secondary amines followed by treatment with acid in a mixture of THF and water. The stability of the furfurals depends to some extent on the nature of the amino group, whereas the reactivity has been shown to be reagent-dependent. When treated with phosphorus ylids, the expected alkenes are formed with E configuration in high yields, but when exposed to nitroalkanes under basic conditions (the Henry reaction) abnormal transformations appear to occur, and 2-acylated furans are obtained, albeit in low yield, instead of nitroalkanols.

New regiospecific synthesis of tri- and tetra-substituted furans.

Beta-acyloxy alpha,beta-unsaturated acetylenic ketones have been shown to react with organocuprate reagents and undergo cyclization followed by dehydration to give substituted furans as the final products. The transformation appeared to be versatile, and tri- and tetra-substituted furans were obtained with regiochemical control in moderate to good yields. The best yields were generally obtained when the reactions were performed around -60 degrees C with substrates and cuprates containing sterically demanding substituents. The proposed mechanism for furan formation has been supported by experiments.

Composition of the water accommodated fractions as a function of exposure times and temperatures.

The water accommodated fractions (WAFs) of nine oils in seawater have been studied. The oils range from light condensate to heavy crude, and include one highly biodegraded oil and one very wax rich oil. This study has identified large variations in the chemical composition of WAFs, depending on oil type, temperature, and mixing time. Experiments at different temperatures (2-13 degrees C) showed that it takes longer time to reach equilibrium at the lowest temperatures, and that this varies for the different oil types. Oils with higher pour point (wax rich oils) need a longer time to establish WAF in equilibrium than oils with lower pour points (naphthenic oils). At 13 degrees C a mixing time of 48h, as recommended in standard procedures, seems to be sufficient for asphalthenic and paraffinic oils. The results demonstrated that for WAF prepared from an unknown oil, or at lower temperatures, different mixing times should be tested. Since the WAF often is used in toxicity testing, the toxicity might be underestimated if the mixing time is too short.