RESUMO
Se-(2-aminoalkyl)selenocysteines were shown to have a chemoprotective activity towards HepG2 cells, contrasting the cell damage of aflatoxin B1. The results of this study suggest that our newly synthesized seleno-diamino acids are apparently endowed with a potent protective potential against cell damage caused by AFB1 similar to, or even higher than, that exerted by the reference compound Se-Me-SeCys. The protective effect does not seem to be absolute, i.e., merely determined by the presence of the chalcogen atom, but rather strictly related to the molecular structure of the new compounds tested. From this point of view, Se-(2-aminoalkyl)selenocysteines may represent a new class of biochemical redox agents fruitfully exploitable to contrast aflatoxin toxicity, at the same time a sound medical application and an economically relevant agricultural issue.
Assuntos
Aflatoxina B1/toxicidade , Antioxidantes/farmacologia , Selenocisteína/análogos & derivados , Selenocisteína/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Citoproteção , Avaliação Pré-Clínica de Medicamentos , Células Hep G2 , Humanos , Concentração Inibidora 50 , OxirreduçãoRESUMO
The synthesis of new substituted prolines carrying at C-4 a second alpha-amino acid residue is reported. The amino acid, L-cysteine or L-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond.
Assuntos
Cisteína/química , Hidroxiprolina/química , Selênio/química , Enxofre/química , Hidroxiprolina/síntese química , Estrutura Molecular , EstereoisomerismoRESUMO
Dipeptides obtained from l-proline and beta(3)-l-amino acids are reported to catalyze enantioselective direct aldol reaction in aqueous medium, leading to significant anti:syn diastereomeric ratios and enantiomeric excesses. The simple introduction of a polar substituent at the C-2 position of the beta(3)-l-amino acid was also found to enhance appreciably both diastereo- and enantioselectivity of the catalyst.
Assuntos
Aldeídos/química , Dipeptídeos/química , Ésteres/química , Prolina/química , Água/química , Benzaldeídos/química , Catálise , Cromatografia Líquida de Alta Pressão , Cicloexanonas/química , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Ressonância Magnética , Prolina/análogos & derivados , Estereoisomerismo , Triptofano/análogos & derivados , Triptofano/química , Tirosina/análogos & derivados , Tirosina/químicaRESUMO
Thirteen new compounds, as well as 16 already known, have been isolated from organic extracts of peels of Cydonia vulgaris, a fruit of a shrub belonging to the same tribe as the apple. All of the structures were elucidated by EI- or ESI-MS and (1)H and (13)C NMR after purification of individual compounds by HPLC. Thirteen fatty acid esters of cinnamyl alcohols, three fatty acid esters of hydroxybenzoic acid, three fatty acid esters of hydroxybenzaldehyde, three glucosides of aromatic acids, four chlorogenic acids, two flavonols, and a benzylamine have been identified. The fatty acid moieties have been identified by GC-MS analysis of the methanolysis products. All of the compounds were tested for their radical scavenging and antioxidant activities by measuring their capacity to scavenge the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and anion superoxide radical and to induce the reduction of Mo(VI) to Mo(V). The chlorogenic acids and the flavonols exhibited more antioxidant and radical scavenger capacity than the positive standards alpha-tocopherol and ascorbic acid. The results of the tests were analyzed by cluster analysis that grouped all of the compounds on the basis of the substituents on the aromatic ring.
Assuntos
Antioxidantes/química , Antioxidantes/isolamento & purificação , Flavonoides/química , Flavonoides/isolamento & purificação , Frutas/química , Fenóis/química , Fenóis/isolamento & purificação , Rosaceae/química , Cromatografia Líquida de Alta Pressão , Sequestradores de Radicais Livres , Espectroscopia de Ressonância Magnética , Polifenóis , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-AtividadeRESUMO
The lipidic beta-amino acid 2-(aminomethyl)-2-pentadecylheptadecanoic acid (1) was synthesized via the alkylation of the C(alpha)-atom of fully protected beta-alanine. Mixed large unilamellar vesicles with a diameter between 100 and 200 nm containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and 1 at a molar ratio of 9 : 1 were prepared and found to have a surface charge which is dependent on pH. At slightly acidic pH, the vesicles were positively charged, and at alkaline pH negatively charged. Dynamic light scattering, zeta potential, and cryo-transmission electron-microscopy measurements indicated that the mixed vesicles fused at pH 4-5 with negatively charged mixed vesicles composed of POPC and POPG (9.8 : 1, molar ratio), POPG being 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)].
Assuntos
Aminoácidos/química , Lipídeos/química , Fosfatidilcolinas/química , Fosfatidilgliceróis/química , Alquilação , Aminoácidos/síntese química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Molecular , Sensibilidade e EspecificidadeRESUMO
Reaction of a lithiated dithiinyl reagent with a O-perbenzylated D-glycono-delta-lactone readily generates the corresponding masked C-vinyl galactosides in high yields and full beta-selectivity. Removal of the sulfur mask renders the free vinyl aglycone with the vinyl group in either the Z or E configuration, depending on the desulfurization conditions chosen.
Assuntos
Galactose/análogos & derivados , Compostos de Vinila/síntese química , Configuração de Carboidratos , Galactose/química , Compostos Heterocíclicos/química , Lítio/química , Espectroscopia de Ressonância Magnética , Conformação Molecular , Estrutura Molecular , Oligossacarídeos/química , Antígeno Sialil Lewis X , Estereoisomerismo , Açúcares Ácidos/química , Compostos de Vinila/químicaRESUMO
O-TBDPS D-glucosamine coupled with l-proline is reported to act as an efficient organocatalyst in the accomplishment of direct aldol reactions. Excellent results, in terms of chemical yields, as well as diastereomeric and enantiomeric ratios, are reported for the catalyzed additions of cyclohexanone and acetone to variously substituted benzaldehydes.
Assuntos
Aldeídos/química , Glucosamina/química , Prolina/análogos & derivados , Prolina/química , Acetona/química , Benzaldeídos/química , Configuração de Carboidratos , Catálise , Cicloexanonas/química , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Ressonância Magnética , Estrutura Molecular , EstereoisomerismoRESUMO
4-Deoxy-l-hexoses were synthesized starting from our previously reported reagent 1 and (R)-benzyl glycidyl ether, which led in few steps to a substituted dihydropyran 6. The stereocontrolled hydroxylation of the latter afforded the corresponding 4-deoxy-l-hexoses 7a, 9, and 11. The same procedure, starting from (S)-benzyl glycidyl ether, enabled the preparation of their d-series enantiomers.