Antioxidant capacity and environmentally friendly synthesis of dihydropyrimidin-(2H)-ones promoted by naturally occurring organic acids.

The Biginelli reaction is a multicomponent reaction involving the condensation between an aldehyde, a ß-ketoester, and urea or thiourea, in the presence of an acid catalyst, producing dihydropyrimidinones (DHPMs). Owing to their important pharmacological properties, the DHPMs have been studied by many authors. However, most of the methodologies used for the synthesis of these compounds require drastic reaction conditions. In the current study, we report an efficient and clean procedure for preparing DHPMs by the use of citric acid or tartaric acid as a promoter of the Biginelli synthesis in ethanol as solvent. In addition, we have evaluated the antioxidant capacity of the compounds synthesized by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and the thiobarbituric acid-reactive species test. Two compounds presented antioxidant activity and also reduced lipid peroxidation at concentrations of 200 and 300 µM. In summary, we report an environmentally friendly procedure for the preparation of DHPMs and demonstrate the antioxidant capacity of some of the compounds.

Dihydropyrimidinones Against Multiresistant Bacteria.

The increase in bacterial resistance to antimicrobials has led to high morbidity and mortality rates, posing a major public health problem, requiring the discovery of novel antimicrobial substances. The biological samples were identified as the Gram-negative bacilli Acinetobacter baumannii, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Morganella morgannii, Pseudomonas aeruginosa and Serratia marcescens and the Gram-positive cocci Enterococcus faecium, and Staphylococcus aureus, all of them resistant to at least three classes of antimicrobials. The antibacterial activity of the compounds was checked in vitro by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) by the broth microdilution method and plating in brain heart infusion (BHI) agar, respectively. The chemical characterization of the compounds was performed by measuring the melting point and gas chromatography coupled with mass spectrometry (GC-MS) on a Shimadzu GC-MS-QP system 2010SE. Synthetic compounds showed antimicrobial activity against Gram-positive cocci at MIC concentrations 0.16-80 µg/ml and Gram-negative bacilli at MIC concentrations 23.2-80 µg/ml. Enterococcus faecium and S. aureus had the best MIC values. The results of the cytotoxicity test indicated that the synthetic compounds showed no significant difference in three concentrations tested (5, 20, and 80 µg/ml), allowing cell viability not different from that assigned to the control, without the tested compounds. In this context, the development of DHPM derivatives brings an alternative and perspective on effectiveness of drugs as potential future antimicrobial agents.

Apoptotic effect of chalcone derivatives of 2-acetylthiophene in human breast cancer cells.

BACKGROUND: A variety of chalcones have demonstrated cytotoxic activity toward several cancer cell lines. This study aimed to investigate the cytotoxicity of four chalcones derivatives of 2-acetylthiophene in human breast cancer cell lines. METHODS: MCF-7 and MDA-MB-231 cells were treated with synthesized chalcones and the cytotoxicity was evaluated by tetrazolium dye (MTT), live/dead, and DAPI assays. RESULTS: Chalcones significantly decreased MCF-7 and MDA-MB-231 cells viability in vitro in a dose dependent manner. After 48h treatment, the IC50 values ranging from 5.52 to 34.23µM. Chalcone 3c displayed the highest cytotoxic activity from all the tested compounds. Cytotoxic effects of compounds were confirmed in the live/dead assay. In addition, DAPI staining revealed that these compounds induce death by apoptosis. CONCLUSION: The data speculate that chalcone derivatives of 2-acetylthiophene may represent a source of therapeutic agents for human breast cancer.

Ultrasound assisted efficient conversion of aromatic aldehydes from oximes.

This work describes the ultrasound-assisted regeneration of aldehydes from oximes in ethanol and phosphoric acid as mediator of the reaction. The large scale regeneration of benzaldehyde was shown under similar conditions. The products were isolated in good yields after short reaction times under mild conditions.

Ultrasound-promoted synthesis of 3-trichloromethyl-5-alkyl(aryl)-1,2,4-oxadiazoles.

The alternative synthesis of 12 1,2,4-oxadiazoles using ultrasound irradiation from trichloroacetoamidoxime and acyl chlorides is reported. Seven of them are novel compounds. The 3-trichloromethyl-5alkyl(aryl)-1,2,4-oxadiazoles have been synthesised in better yields and shorter reaction times compared to the conventional method. This protocol can be applicable for preparation of 1,2,4-oxadiazoles containing aryl or alkyl groups attached at their C-5 side-chain.