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1.
Molecules ; 26(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34299561

RESUMO

Fucus spiralis that was collected in the four seasons was submitted to an extraction with ethanol:water (crude extracts Et80), followed by a liquid-liquid fractionation with organic solvents (fraction He from n-hexane; aqueous fractions AQ1, AQ2, AQ3 and AQ4; ethyl acetate fraction EA), with the aim of obtaining phlorotannin-enriched extracts. All the extracts (Et80, He, AQ1, AQ2, AQ3, AQ4 and EA) that were obtained for the F. spiralis of the four seasons were evaluated for their antioxidant capacity and total phenolic compounds. The summer extracts presented the highest contents in polyphenols (TPC), as well as the highest ferric reducing antioxidant power (FRAP), when compared to the samples from the other seasons. The reductive percentage of the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) compound was similar between the seasons. For all the seasons, the EA extract showed the highest polyphenol content (TPC), and the highest antioxidant capacity (highest ferric reducing power (FRAP) and lowest concentration needed to reduce 50% of the DPPH compound), which is in agreement with a phlorotannin-enriched fraction. This study revealed that the polyphenol content and antioxidant power of the F. spiralis extracts are influenced by the time of harvest, as well as by the solvents used for their extraction.


Assuntos
Fucus/química , Polifenóis/análise , Taninos/análise , Antioxidantes/análise , Estações do Ano , Alga Marinha/química , Solventes
2.
Molecules ; 26(10)2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34068969

RESUMO

The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100 °C and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70 °C. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.


Assuntos
Antioxidantes/farmacologia , Sefarose/análogos & derivados , Tirosina/química , Aerobiose , Anti-Infecciosos/farmacologia , Benzotiazóis/química , Compostos de Bifenilo/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Oxirredução , Picratos/química , Porphyra/química , Espectroscopia de Prótons por Ressonância Magnética , Sefarose/química , Sefarose/isolamento & purificação , Sefarose/farmacologia , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Ácidos Sulfônicos/química , Tirosina/síntese química
3.
Dalton Trans ; 50(1): 157-169, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33290472

RESUMO

Four new ligand precursors (H2L1-H2L4), derived from the Mannich condensation of two amino acids (l-Val and l-Phe) and two 3,5-disubstituted phenols (t-Bu or Me), and the corresponding oxidovanadium(iv) (1-4) and copper(ii) (6-7) complexes are synthesized. Two other related compounds (H2L5 and H2L6), containing an additional 2-methyl-pyridine arm, and the corresponding VIVO (5) and CuII (8-9) complexes were also obtained. All metal complexes are monomeric in the solid state, having a solvent molecule or a chloride ion in the coordination sphere. The in vitro cytotoxic activity of all compounds is evaluated against cancer cells from different origins. The IC50 values at 72 h are in the range of 6-15 µM for HeLa cells, 4-17 µM for A-549 cells and >25 µM for MDA-MB-231 cells, except for [VIVOL1(CH3OH)] (1) and [CuL6(H2O)] (9). With the exception of H2L6, overall, the metal complexes are more cytotoxic than the corresponding ligand precursors. Globally, the cellular viability data show that (i) the l-Phe derived compounds are more cytotoxic than the corresponding l-Val complexes; (ii) the presence of the bulkier t-Bu groups increases the cytotoxicity; (iii) the presence of a 2-methyl-pyridine arm increases considerably the cytotoxicity; and (iv) the CuII-complexes are more cytotoxic than the VIVO-compounds. Complexes [VIVOL3(CH3OH)] (3), [CuL3(H2O)] (7) and [CuL5(H2O)] (8) were further evaluated and their mechanism of action was determined to be apoptosis, evidenced by AnnexinV staining and the increase in caspase 3/7 activity. Compounds 3, 7 and 8 also exhibit DNA cleavage activity, involving the formation of reactive oxygen species and were able to induce genomic damage in cells as determined by COMET assay.


Assuntos
Antineoplásicos , Complexos de Coordenação , Cobre , Fenóis , Fenilalanina , Valina , Vanadatos , Antineoplásicos/química , Antineoplásicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Cobre/química , Cobre/farmacologia , Clivagem do DNA , Dano ao DNA , Células HeLa , Humanos , Ligantes , Fenóis/química , Fenóis/farmacologia , Fenilalanina/química , Fenilalanina/farmacologia , Valina/química , Valina/farmacologia , Vanadatos/química , Vanadatos/farmacologia
4.
Molecules ; 25(18)2020 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-32899518

RESUMO

Incorporation of antioxidant agents in edible films and packages often relies in the usage of essential oils and other concentrated hydrophobic liquids, with reliable increases in antimicrobial and antioxidant activities of the overall composite, but with less desirable synthetic sources and extraction methods. Hydroethanolic extracts of commercially-available red macroalgae Gracilaria gracilis were evaluated for their antioxidant potential and phenolic content, as part of the selection of algal biomass for the enrichment of thermoplastic film coatings. The extracts were obtained through use of solid-liquid extractions, over which yield, DPPH radical reduction capacity, total phenolic content, and FRAP activity assays were measured. Solid-to-liquid ratio, extraction time, and ethanol percentages were selected as independent variables, and response surface methodology (RSM) was then used to estimate the effect of each extraction condition on the tested bioactivities. These extracts were electrospun into polypropylene films and the antioxidant activity of these coatings was measured. Similar bioactivities were measured for both 100% ethanolic and aqueous extracts, revealing high viability in the application of both for antioxidant coating purposes, though activity losses as a result of the electrospinning process were above 60% in all cases.


Assuntos
Antioxidantes/farmacologia , Aditivos Alimentares/farmacologia , Gracilaria/química , Modelos Teóricos , Polietilenoglicóis/química , Polipropilenos/química , Análise de Regressão
5.
ChemMedChem ; 14(7): 770-778, 2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30694018

RESUMO

New cyclam derivatives (HOCH2 CH2 CH2 )2 (PhCH2 )2 Cyclam and (HOCH2 CH2 CH2 )2 ( 4-CF3 PhCH2 )2 Cyclam, as well as their CuII and FeIII complexes, were synthesized and characterized and their stability in cellular media was assessed. The cytotoxic effect of all compounds was examined on human cervical cancer (HeLa) cells, revealing strong anticancer activity. After 24 h, only complexes with the (HOCH2 CH2 CH2 )2 ( 4-CF3 PhCH2 )2 Cyclam ligand are cytotoxic, whereas after incubation for 72 h all compounds show significant antiproliferative effects. Notably, compounds containing 4-CF3 PhCH2 pendant arms on the cyclam ring revealed the most activity, with cytotoxicity values up to 12 times higher than those of cisplatin. All metal complexes seem to induce cell death through the formation of reactive oxygen species.


Assuntos
Antineoplásicos/farmacologia , Cobre/química , Ciclamos/farmacologia , Compostos Férricos/química , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/farmacologia , Antineoplásicos/química , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ciclamos/química , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Células HeLa , Humanos , Substâncias Macromoleculares/química , Espécies Reativas de Oxigênio/metabolismo , Análise Espectral/métodos , Relação Estrutura-Atividade , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologia
6.
Dalton Trans ; 47(33): 11358-11374, 2018 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-30059099

RESUMO

The synthesis and characterization of an oxidovanadium(iv) [VIVO(L)(acac)] (1) and of two dioxidovanadium(v) [VVO2(L')] (2) and [VVO2(L)] (2a) complexes of the Schiff base formed from the reaction of 4-(p-fluorophenyl) thiosemicarbazone with pyridine-2-aldehyde (HL) are described. The oxidovanadium(iv) species [VIVO(L)(acac)] (1) was synthesized by the reaction of VIVO(acac)2 with the thiosemicarbazone HL in refluxing ethanol. The recrystallization of [VIVO(L)(acac)] (1) in DMF, CH3CN or EtOH gave the same product i.e. the dioxidovanadium(v) complex [VVO2(L)] (2a); however, upon recrystallization of 1 in DMSO a distinct compound [VVO2(L')] (2) was formed, wherein the original ligand L- is transformed to a rearranged one, L'-. In the presence of DMSO the ligand in complex 1 is found to undergo methylation at the carbon centre attached to imine nitrogen (aldimine) and transformed to the corresponding VVO2-species through in situ reaction. The synthesized HL and the metal complexes were characterized by elemental analysis, IR, UV-Vis, NMR and EPR spectroscopy. The molecular structure of [VVO2(L')] (2) was determined by single crystal X-ray crystallography. The methylation of various other ligands and complexes prepared from different vanadium precursors under similar reaction conditions was also attempted and it was confirmed that the imine methylation observed is both ligand and metal precursor specific. Complexes 1 and 2 show in vitro insulin-like activity against insulin responsive L6 myoblast cells, higher than VIVO(acac)2, with complex 1 being more potent. In addition, the in vitro cytotoxicity studies of HL, and of complexes 1 and 2 against the MCF-7 and Vero cell lines were also done. The ligand is not cytotoxic and complex 2 is significantly more cytotoxic than 1. DAPI staining experiments indicate that an increase in the time of incubation and an increase of concentration of the complexes lead to the increase in cell death.

7.
Dalton Trans ; 44(40): 17736-55, 2015 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-26399883

RESUMO

The reaction of the tripodal tetradentate dibasic ligand 6,6'-(2-(pyridin-2-yl)ethylazanediyl)bis(methylene)bis(2,4-di-tert-butylphenol), H2L(1)I, with [V(IV)O(acac)2] in CH3CN gives the V(V)O-complex, [V(V)O(acac)(L(1))] 1. Crystallisation of 1 in CH3CN at ∼0 °C gives dark blue crystals of 1, while at room temperature it affords dark green crystals of [{V(V)O(L(1))}2µ-O] 3. Upon prolonged treatment of 1 in MeOH, [V(V)O(OMe)(MeOH)(L(1))] 2 is obtained. All three complexes were analysed by single-crystal X-ray diffraction, depicting a distorted octahedral geometry around vanadium. In the reaction of H2L(1) with V(IV)OSO4 partial hydrolysis of the tripodal ligand results in the elimination of the pyridyl fragment of L(1) and the formation of H[V(V)O2(L(2))] 4 containing the ONO tridentate ligand 6,6'-azanediylbis(methylene)bis(2,4-di-tert-butylphenol), H2L(2)II. Compound 4, which was not fully characterised, undergoes dimerization in acetone yielding the hydroxido-bridged [{V(V)O(L(2))}2µ-(OH)2] 5 having a distorted octahedral geometry around each vanadium. In contrast, from a solution of 4 in acetonitrile, the dinuclear compound [{V(V)O(L(2))}2µ-O] 6 is obtained, with a trigonal bipyramidal geometry around each vanadium. The methoxido complex 2 is successfully employed as a functional catechol-oxidase mimic in the oxidation of catechol to o-quinone under air. The process was confirmed to follow a Michaelis-Menten type kinetics with respect to catechol, the Vmax and KM values obtained being 7.66 × 10(-6) M min(-1) and 0.0557 M, respectively, and the turnover frequency is 0.0541 min(-1). A similar reaction with the bulkier 3,5-di-tert-butylcatechol proceeded at a much slower rate. Complex 2 was also used as a catalyst precursor for the oxidative bromination of thymol in aqueous medium. The selectivity shows quite interesting trends, namely when not using excess of the primary oxidizing agent, H2O2, the para mono-brominated product corresponds to ∼93% of the products and no dibromo derivative is formed.


Assuntos
Materiais Biomiméticos/química , Compostos Organometálicos/química , Vanádio/química , Aminas/química , Benzoquinonas/química , Materiais Biomiméticos/síntese química , Catecol Oxidase/metabolismo , Catecóis/química , Halogenação , Peróxido de Hidrogênio/química , Ligantes , Compostos Organometálicos/síntese química , Oxirredução , Temperatura , Timol/química
8.
J Inorg Biochem ; 141: 83-93, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25226436

RESUMO

Several mixed ligand vanadium and copper complexes were synthesized containing 8-hydroxyquinoline (8HQ) and a ligand such as picolinato (pic(-)), dipicolinato (dipic(2-)) or a Schiff base. The complexes were characterized by spectroscopic techniques and by single-crystal X-ray diffraction in the case of [V(V)O(L-pheolnaph-im)(5-Cl-8HQ)] and [V(V)O(OMe)(8HQ)2], which evidenced the distorted octahedral geometry of the complexes. The electronic absorption data showed the presence of strong ligand to metal charge transfer bands, significant solvent effects, and methoxido species in methanol, which was further confirmed by (51)V-NMR spectroscopy. The structures of [Cu(II)(dipic)(8HQ)]Na and [V(IV)O(pic)(8HQ)] were confirmed by EPR spectroscopy, showing only one species in solution. The biological activity of the compounds was assessed through the minimal inhibitory concentration (MIC) of the compounds against Mycobacterium tuberculosis (Mtb) and the cytotoxic activity against the cisplatin sensitive/resistant ovarian cells A2780/A2780cisR and the non-tumorigenic HEK cells (IC50 values). Almost all tested vanadium complexes were very active against Mtb and the MICs were comparable to, or better than, the MICs of drugs, such as streptomycin. The activity of the complexes against the A2780 cell line was dependent on incubation time presenting IC50 values in the 3-14 µM (at 48 h) range. In these conditions, the complexes were significantly (*P<0.05-**P<0.001) more active than cisplatin (22 µM), in the A2780 cells and even surpassing its activity in the cisplatin-resistant cells A2780cisR (2.4-8 µM vs. 75.4; **P<0.001). In the non-tumorigenic HEK cells poor selectivity toward cancer cells for most of the complexes was observed, as well as for cisplatin.


Assuntos
Antineoplásicos/síntese química , Antituberculosos/síntese química , Complexos de Coordenação/síntese química , Cobre/química , Hidroxiquinolinas/síntese química , Vanádio/química , Antineoplásicos/farmacologia , Antituberculosos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cisplatino/farmacologia , Complexos de Coordenação/farmacologia , Células HEK293 , Humanos , Hidroxiquinolinas/farmacologia , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Modelos Moleculares , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/crescimento & desenvolvimento , Ácidos Picolínicos/química , Bases de Schiff/química , Relação Estrutura-Atividade
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