Electrochemical and associated techniques for the study of the inclusion complexes of thymol and β-cyclodextrin and its interaction with DNA

Thymol, a potent agent for microbial, fungal, and bacterial disease, has low aqueous solubility and it is genotoxic, i.e., is capable of damaging deoxyribonucleic acid (DNA). This possible problem of DNA toxicity needs to be solved to allow the use of different doses of thymol. This study characterized the inclusion compound containing thymol and beta-cyclodextrin (beta-CD) by measuring the interaction between these two components and the ability of thymol to bind DNA in its free and beta-CD complexed form. The encapsulation approach using beta-CD is particularly useful when controlled target release is desired, and a compound is insoluble, unstable, or genotoxic. The interaction between thymol and DNA has been studied using electrochemical quartz crystal microbalance (EQCM), atomic force microscopy (AFM), and differential pulse voltammetry (DPV). The characterization of the inclusion complex of thymol and beta-CD was analyzed by UV-vis spectrophotometry, cyclic voltammetry, and scanning electrochemical microscopy (SECM). Based on the free beta-CD by spectrophotometry method, the association constant of thymol with the beta-CD was estimated to be 2.8 x 10(4) L mol(-1). The AFM images revealed that in the presence of small concentrations of thymol, the dsDNA molecules appeared less knotted and bent on the mica surface, showing significant damage to DNA. The SECM and voltammetry results both demonstrated that the interaction of thymol-beta-CD complex was smaller than the free compound showing that the encapsulation process may be an advantage leading to a reduction of toxic effects and increase of the bioavailability of the drug.Brazilian agency CNPq Brazilian agency CAPES Brazilian agency FAPEAL Brazilian agency Organization of American States (OAS

On the investigation of hybrid quinones: synthesis, electrochemical studies and evaluation of trypanocidal activity

Submitted by sandra infurna ([email protected]) on 2016-04-26T17:45:05Z No. of bitstreams: 1 kelly_salomão_etal_IOC_2015.pdf: 1493604 bytes, checksum: dfff0c13bf020d699151d4e2725b8f2a (MD5)Approved for entry into archive by sandra infurna ([email protected]) on 2016-04-27T13:20:56Z (GMT) No. of bitstreams: 1 kelly_salomão_etal_IOC_2015.pdf: 1493604 bytes, checksum: dfff0c13bf020d699151d4e2725b8f2a (MD5)Made available in DSpace on 2016-04-27T13:20:56Z (GMT). No. of bitstreams: 1 kelly_salomão_etal_IOC_2015.pdf: 1493604 bytes, checksum: dfff0c13bf020d699151d4e2725b8f2a (MD5) Previous issue date: 2015Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Laboratório de Biologia CeUniversidade Federal de Minas Gerais. Instituto de Ciências Exatas. Departamento de Química. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Instituto de Ciências Exatas. Departamento de Química. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Escola de Farmácia. Belo Horizonte, MG, Brasil.Universidade Federal de Minas Gerais. Escola de Farmácia. Belo Horizonte, MG, Brasil.Universidade Federal de Alagoas. Instituto de Química e Biotecnologia. Maceió, AL, Brasil.Universidade Federal de Alagoas. Instituto de Química e Biotecnologia. Maceió, AL, Brasil.Universidade Federal de Santa Catarina. Departamento de Química. Florianópolis, SC, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Laboratório de Biologia CeFundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Laboratório de Biologia CeFundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Laboratório de Biologia CeFundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Laboratório de Biologia CeIn our continued search for novel trypanocidal compounds, arylamine, chalcone, triazolic, triazole– carbohydrate and chalcogenium derivatives containing a naphthoquinone scaffold were prepared; in addition to electrochemical studies, these compounds were evaluated against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. Among the thirty-eight compounds herein evaluated, six were found to be more potent against trypomastigotes than the standard drug benznidazole, with IC50/24 h values between 52.9 and 89.5 mM

Development of a Polymeric Membrane Impregnated with Poly-Lactic Acid (PLA) Nanoparticles Loaded with Red Propolis (RP)

The main objectives of this study were to develop and characterize hydrophilic polymeric membranes impregnated with poly-lactic acid (PLA) nanoparticles (NPs) combined with red propolis (RP). Ultrasonic-assisted extraction was used to obtain 30% (w/v) red propolis hydroalcoholic extract (RPE). The NPs (75,000 g mol−1) alone and incorporated with RP (NPRP) were obtained using the solvent emulsification and diffusion technique. Biopolymeric hydrogel membranes (MNPRP) were obtained using carboxymethylcellulose (CMC) and NPRP. Their characterization was performed using thermal analysis, Fourier transform infrared (FTIR), total phenols (TPC) and flavonoids contents (TFC), and antioxidant activity through the radical scavenging assay with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric reducing antioxidant power (FRAP). The identification and quantification of significant RP markers were performed through UPLC-DAD. The NPs were evaluated for particle size, polydispersity index, and zeta potential. The TPC for RPE, NPRP, and MNPRP was 240.3 ± 3.4, 191.7 ± 0.3, and 183.4 ± 2.1 mg EGA g−1, while for TFC, the value was 37.8 ± 0.9, 35 ± 3.9, and 26.8 ± 1.9 mg EQ g−1, respectively. Relevant antioxidant activity was also observed by FRAP, with 1400.2 (RPE), 1294.2 (NPRP), and 696.2 µmol Fe2+ g−1 (MNPRP). The primary markers of RP were liquiritigenin, isoliquiritigenin, and formononetin. The particle sizes were 194.1 (NPs) and 361.2 nm (NPRP), with an encapsulation efficiency of 85.4%. Thermal analysis revealed high thermal stability for the PLA, nanoparticles, and membranes. The DSC revealed no interaction between the components. FTIR allowed for characterizing the RPE encapsulation in NPRP and CMC for the MNPRP. The membrane loaded with NPRP, fully characterized, has antioxidant capacity and may have application in the treatment of skin wounds

Nature of Electrogenerated Intermediates in Nitro-Substituted Nor-β-lapachones: The Structure of Radical Species during Successive Electron Transfer in Multiredox Centers

Electrochemical, spectroelectrochemical, and theoretical studies of the reduction reactions in nor-β-lapachone derivatives including a nitro redox center showed that reduction of the compounds involves the formation of several radical intermediates, including a biradical dianion resultant from the separate reduction of the quinone and nitro groups in the molecules. Theoretical descriptions of the corresponding Fukui functions <i>f</i>_αα⁺ and <i>f</i>_ββ⁺(<b>r</b>) and LUMO densities considering finite differences and frozen core approximations for describing the changes in electron and spin densities of the system allowed us to confirm these results. A description of the potential relationship with the obtained results and biological activity selectivity indexes suggests that both the formation of stable biradical dianion species and the stability of the semiquinone intermediates during further reduction are determining factors in the description of their biological activity