Multicomponent access to novel proline/cyclized cysteine tethered monastrol conjugates as potential anticancer agents

The versatility of multicomponent Biginelli’s reaction is exploited in the development of proline and cyclized cysteine tethered conjugates of monastrol, a kinesin Eg5 inhibitor. Ten new conjugates are synthesized focusing on structural replacement of the ester moiety (C-5 position) of the monastrol backbone with amino acid based amide moieties. On cytotoxic evaluation, conjugate 24 has shown promising in vitro cytotoxic activity against leukemia. Molecular docking studies revealed that the conjugates 19 and 24 exhibit better interaction at kinesin Eg5 receptor compared to monastrol. Moreover, computational calculations and predictions of important molecular properties suggest that these new amino acid based conjugates could be further improved to provide potential anticancer agents.     

Selective spectrophotometric determination of ascorbic acid in drugs and foods

A new analytical method was developed for the determination of ascorbic acid. The method is based on the reaction of ascorbic acid with 4-chloro-7-nitrobenzofurazane (NBD-Cl) in the presence of 0.2M sodium hydroxide, where a bluish green colour (lambda(max) 582 nm) is developed after dilution with 50% (v/v) aqueous acetone solution. Beer's law was obeyed in a concentration range of 5-20 microg ascorbic acid/ml with a good correlation coefficient (r = 0.9990). The method was found to be highly specific for the determination of ascorbic acid in the presence of dehydro-ascorbic acid, all other vitamins and minerals possibly present in multivitamin preparations, rutin, salicylamide, acetyl salicylic acid, paracetamol, caffeine, phenylephrine hydrochloride and dipyrone. Moreover, the proposed procedure was also successfully applied for the determination of ascorbic acid in some canned and fresh fruit juices, some vegetables and infant milk products without interference from coloured and other substances present in the plant extracts.     

Composition of the essential oil of wild growing Artemisia vulgaris from Erie, Pennsylvania

Essential oil from wild growing Artemisia vulgaris L. originating in Erie, Pennsylvania was obtained by hydrodistillation of the aerial parts of the plant. Gas chromatographic-mass spectral analysis was used to identify the major volatiles present. Up to 22 components were detected in the essential oils. Germacrene D (25%), Caryophyllene (20%), alpha-Zingiberene (15%) and Borneol (11%) represent the major components of leaf oil, while the buds were rich in 1,8-Cineole (32%), Camphor (16%), Borneol (9%), and Caryophyllene (5%). trans-2-Hexenal was also detected in the aerial parts of the plant. alpha-Zingiberene and trans-2-Hexenal have not been previously reported for Artemisia vulgaris L. The major analytes are compared to those from Artemisia vulgaris L, originating outside of the United States.     

Spatial arrangement of carbon nanotubes in TiO2 photoelectrodes to enhance the efficiency of dye-sensitized solar cells

Three electrode structures with different spatial arrangements of carbon nanotubes (CNTs) in the mesoporous TiO(2) layer were employed in dye-sensitized solar cells to study the effect of surface states at the interface formed by the incorporation of CNTs. It was found that the decay of open circuit voltage (V(oc)) was significantly minimized by avoiding the direct contact of nanotubes to the conducting substrate by introducing a thin buffer layer of TiO(2) while maintaining the superior electron collection efficiency from the incorporation of nanotubes.     

Preparation and evaluation of thermally stable nano-structured self-doped polythiophene coating for analysis of phthalate ester trace levels

Nano‐structured self‐doped polythiophene (SPT) electrodeposited in the presence of fluorinated organic acid was applied as a thermally stable conductive polymer‐based solid‐phase microextraction (SPME) fiber candidate. Quantitative determination of trace levels of phthalate esters including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP) was carried out using this novel fiber, coupling with gas chromatography‐flame ionization detector (GC‐FID). The SPT coating was proved to be stable at high temperatures (～350°C) with a high extraction capacity and long lifetime (more than 60 times). Improved temperature resistance was obtained by the presence of sulfonated groups in the backbone of polymer. Thermal stability of novel SPT was superior to common polythiophene (synthesized in LiClO₄). The extraction procedure was optimized by means of the Taguchi orthogonal array experimental design with an OA₁₆ (4⁵) matrix including extraction temperature, extraction time, salt concentration, stirring rate, and headspace volume. The good linearity was obtained for most compounds with correlation coefficients (R²) of between 0.993 and 0.995. The detection limits were lower than 0.12 ng/mL for dimethyl phthalate, DEP, dibutyl phthalate, and diethylhexyl phthalate. The method was successfully applied to the analysis of water samples with the recoveries from 90±1 to 107±1%.     

Evaluation of Antimicrobial Activity of Some Newly Synthesized 4‐Thiazolidinones

The antimicrobial activity of thirteen newly synthesized 4‐thiazolidinones (TZONs) and four dithiolane derivatives was assessed against susceptible and resistant bacteria, including MRSA, as well as Candida albicans. The structure‐activity relationships revealed that 4‐Thiazolidinone derivatives harboring p‐chlorophenyl and dicarboxyethyl at the 2‐ethenyl and 5‐arylidine positions of the thiazolidinone ring display considerable antibacterial properties. No antifungal activity was recorded by all tested compounds against Candida albicans. The possible potentiative (synergistic) effect of the most active compounds to a few commercial antibiotics was also investigated.     

Evaluation of Antifungal and Antioxidant Activity of Newly Synthesized 4‐Thiazolidinones

The antifungal and antioxidant activities of thirty newly synthesized 4‐thiazolidinone (TZON) derivatives were assessed against some fungal species including Candida albicans and Aspergillus niger. The introduction of different arylidene moieties at 5‐positions of the thiazolidinone ring successfully enhanced its biological activity. The structure–activity relationships revealed that 4‐thiazolidinone derivatives harboring dicarboxyethyl (at the 2‐ethenyl) and p‐nitrophenylhydrazyl arm (at the 5‐arylidine positions of the thiazolidinone ring) display considerable antifungal and antioxidant properties.     

Short Synthesis of COX-2 Inhibitor Inotilone

An efficient three-step synthesis of COX-2 inhibitor inotilone from acetaldoxime is described. The structure of inotilone was elucidated via an aldol reaction between 5-methyl-3(2H)-furanone and 3,4-dihydroxybenzaldehyde. This approach describes a convenient pathway to 5-alkyl-3-furanones through isoxazole chemistry.     

Uncommon perspectives in palladium- and copper-catalysed arylation and heteroarylation of terminal alkynes following Heck or Sonogashira protocols: Interactions copper/ligand,formation of diynes,reaction and processes in ionic liquids

Conjugated alkynes are recurring building blocks in natural products and in a wide range of important compounds, such as pharmaceuticals, agrochemicals, or molecular materials. The palladium-catalysed cross-coupling reaction between the sp²-hybridized carbon atoms of aryl, heteroaryl, and vinyl halides with the sp-hybridized carbon atoms of terminal alkynes is one of the most important developments in the field of alkyne chemistry over the past 50 years. Room for improvement still exists in these important reactions of direct arylation of terminal alkynes. In this prospect, the present authors have developed several strategies aiming at improving the reactivity, the selectivity, and several aspects of processes involving the palladium-catalysed alkyne arylation and heteroarylation reactions, in relation with sustainable chemistry. Various original approaches have thus been adopted: (i) the development of catalytic systems efficient at low metal loading below 1 mol% of palladium and copper (to reduce metal contamination) from polydentate ligands chemistry, (ii) the limitation of diyne formation by undesired side-reaction, this from a better mechanistic understanding and the innovating use of copper adducts, (iii) and the development of cost-efficient catalytic reactions in ionic liquid solvents. These topics have been developed with the general outlook of a large scope in organic synthesis. In addition, the investigation of recycling opportunities and the unprecedented production of extendedly conjugated bis(aryl)diynes has been also achieved. The present account reviews all this work, as it has been presented by the corresponding author at GECOM–CONCOORD 2012 as recipient of the 2012 European journal of Inorganic Chemistry Young Investigator Award.     

Tetronamides as latent acyclic vinylogous amides in formal aza-[3 + 3] cycloaddition reactions with alpha,beta-unsaturated iminium salts. An unexpected rearrangement and an approach to synthesis of substituted piperidines

A detailed account regarding formal aza-[3 + 3] cycloaddition reactions of tetronamides with alpha,beta-unsaturated iminium salts is described here. This investigation uncovers regioisomeric cycloadducts that were not found in previous studies involving this formal cycloaddition and an unexpected rearrangement that led to pyridines and dihydropyridines. Both stereochemical and regiochemical issues raised in this study provide further mechanistic insights into this cycloaddition. With careful control of reaction temperatures, the desired formal cycloadducts are obtained. Ensuing transformation of these cycloadducts into functionalized piperidines establishes the concept of employing tetronamides as latent acyclic vinylogous amides for the formal aza-[3 + 3] cycloaddition.