Marina Ritter

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.

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 β‐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.

Recent Advances on the Synthesis of Chalcones with Antimicrobial Activities: A Brief Review

Abstract: The increasing resistance of bacteria and fungi to antimicrobial drugs has been a matter of concern in public health in the last decades. The continuing need for novel therapeutic compounds is still urgent regarding the number of new diseases and resistant strains of microorganisms. Chalcones are ketones , -unsaturated with one aromatic ring bonded to carbonyl and another aromatic ring bonded to an olefin function. Literature has already reported the antimicrobial potential of several chalcones against a wide range of fungal and bacterial strains, including resistant ones; clearly indicating that they are attractive target compounds for new antimicrobial drug development. Several studies have shown that the introduction of different functional groups is a strategy used to improve the biological activity of these compounds, moreover, the structure of chalcones can also be employed as an intermediate reaction, enabling different reactions and giving rise to new molecules. In this review, we describe recent advances on the synthesis of chalcones with antimicrobial activities.

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.

Synthesis of Biodiesel from Grape Seed Oil Using Ultrasound Irradiation

Biodiesel is a mixture of fatty esters obtained by transesterification of triglycerides with low molecular weight alcohols, such as methanol and ethanol. The transesterification reaction is slow at room temperature and therefore require the use of catalysts. In this work, conventional heating sources were replaced by ultrasound in the presence of KOH and methanol. The oil was obtained from grape seed, a byproduct of the wineries. The biodiesel was obtained in 97% yield, at the time of 30 minutes and the fatty acids of grape oil were characterized by gas chromatography and evaluated the parameters viscosity, iodine, and acidic saponification.

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.