Rossimiriam Pereira de Freitas Gil

Antimycobacterial and cytotoxicity activity of synthetic and natural compounds

Antimycobacterial and cytotoxicity activity of synthetic and natural compounds. Secondary metabolites from Curvularia eragrostidis and Drechslera dematioidea, Clusia sp. floral resin, alkaloids from Pilocarpus alatus, salicylideneanilines, piperidine amides, the amine 1-cinnamylpiperazine and chiral pyridinium salts were assayed on Mycobacterium tuberculosis H37Rv. N-(salicylidene)-2-hydroxyaniline was the most effective compound with a minimal inhibitory concentration (MIC) of 8 µmol/L. Dihydrocurvularin was moderately effective with a MIC of 40 µmol/L. Clusia sp. floral resin and a gallocatechin-epigallocatechin mixture showed MIC of 0.02 g/L and 38 µmol/L, respectively. The cytotoxicity was evaluated for N-(salicylidene)-2-hydroxyaniline, curvularin, dihydrocurvularin and Clusia sp. floral resin, and the selectivity indexes were > 125, 0.47, 0.75 and 5, respectively.

Synthesis of C60(OH)18-20 in aqueous alkaline solution under O2-atmosphere

In this work we report on an alternative synthesis of water-soluble fullerenes known as fullerols, aiming for biomedical applications. The synthesis is based on a process in which polyethylene glycol (PEG400) is used as phase-transfer catalyst between fullerene/benzene and aqueous NaOH solutions. The polyhydroxylation of the fullerenes occurs in the NaOH solution under a continuous flow of O2 to enhance the reaction yield. The resulting compound was characterized with infrared spectroscopy, nuclear magnetic resonance, thermo-gravimetric analysis and optical absorption. The formation of C60(OH)18-20 in high yields was confirmed.

An enantioselective synthesis of isoquinuclidines from 3-substituted chiral pyridinium salts

Abstract A new enantioselective approach to chiral isoquinuclidines, such as 15 , 18 and 21 , is reported. The key step of these syntheses is a cycloaddition between chiral dihydropyridines 14 or 20 , now readily available from tetrahydropyridinium salts 6 or 11 , and achiral dienophiles. The reaction proceeds with a very good endo -selectivity and moderate d.e.

An access to some functionalized azocine derivatives

The syntheses, from readily accessible 3-alkyl-4-methoxy-1,3,4,5-tetrahydropyridine 1, of functionalized 1,6,7,8-tetrahydroazocine 7 and 1,2,7,8-tetrahydroazocine 9 are reported.

Estudo da capacidade de complexação de íons Cu2+ em solução aquosa usando celulose modificada com anidrido succínico e com poliaminas

This work describes the preparation of new materials, derived from cellulose, to be used as complexing agents for heavy metal ions in aqueous solutions and, hence, to decontaminate waters polluted by such metals. The first part deals with the chemical modification of the cellulose using succinic anhydride. The carboxylic acid functions introduced in the material were used to anchor polyamines resulting in three novel modified celluloses. The materials obtained were characterized by elemental analysis and infrared spectroscopy (IR). The second part of the work features the evaluation of the adsorption capacity of the modified celluloses in relation to Cu 2+ ions in aqueous solutions. The study was accomplished by titration, a traditional analytical method. The various materials showed a maximum complexing capacity ranging from 141 to 263 mg of Cu 2+ per gram of the modified material. The efficiency for the complexation of Cu 2+ ions was proportional to the number of amine functions introduced in cellulose.

Microwave‐Assisted Rapid Deacetalation of Carbohydrates

Abstract A simple and fast procedure to deprotect carbohydrate 4,6‐di‐O‐benzylidene acetals was accomplished by using domestic microwave‐oven irradiation in solvent‐free conditions and with silica‐gel‐supported reagents.

Synthesis of New Tetrazole Derivatives of α,α‐Trehalose

Abstract Five new nitrogen heterocycles, mono‐and disubstituted tetrazoles with potential synthetic and pharmacological interest, were synthesized from α, α‐trehalose via the alkylation of commercial tetrazoles. This method appears to have broad scope with respect to the variations at positions 1 and 2 of tetrazole.

Microwave‐Assisted Xanthone Synthesis

Abstract Xanthones have been prepared by microwave irradiation–assisted cyclization of 2‐hydroxy‐2′‐methoxy benzophenone precursors in a short time and good yields.