RESUMO
We report for the first time the immunoadjuvant effects of lipoconjugation of peptide antigens in an in vitro system by using CD4+ T-cells. The lipopeptides obtained by conjugating a palmitoyl moiety at the N(alpha)-terminal of Gln(74) or at the epsilon-NH(2) of Lys(75) of GpMBP(74-85) induced increased T-cell responsiveness compared to the native nonlipidated peptide. On the other hand, lipoderivatives of GpMBP(82-98) did not increase the T-cell response, demonstrating that the superagonist inducing effect of lipoconjugation is epitope-specific. Digestion of the two native peptides with cathepsin D and L, both implicated in antigen processing, and with a complete lysosomal fraction of a EBV-transformed B cell line shows that GpMBP(74-85) is resistant to cellular proteases, while GpMBP(82-98) is easily digested by these enzymes. These results suggest that the first prerequisite for increasing the T-cell response by lipoconjugation is the stability of the native peptide to peptidases, providing an important insight into the understanding of the immunoadjuvant effect of lipoderivative antigens.
Assuntos
Linfócitos T CD4-Positivos/efeitos dos fármacos , Lipoproteínas/síntese química , Proteína Básica da Mielina/imunologia , Ácido Palmítico/química , Fragmentos de Peptídeos/imunologia , Peptídeo Hidrolases/química , Animais , Linfócitos T CD4-Positivos/imunologia , Catepsina D/química , Catepsina L , Catepsinas/química , Divisão Celular , Cisteína Endopeptidases , Epitopos , Feminino , Técnicas In Vitro , Lipoproteínas/química , Lipoproteínas/farmacologia , Lisossomos/enzimologia , Ratos , Ratos Endogâmicos Lew , Relação Estrutura-AtividadeRESUMO
The heterocyclic moiety of 17 beta-(2-aminooxazol-4-yl) steroids is sensitive to the oxidizing action of hydrogen peroxide and yields products mainly from the opening of the amino-oxazole ring. Unlike simple 2-aminooxazoles, it does not rearrange to 2-imidazolone and the expected steroidal hydroperoxyimidazolidinones were not detected. Among the substances we isolated, N-(aminocarbonyl)-17 alpha-hydroxy-17-carboxamides (2a) and (3a) undergo spontaneous cyclization, in the reaction conditions, giving steroid-17-spirooxazolidinediones (2d) and (3d). Spirane (2d) was synthesized in high yields from (2a) in strongly alkaline medium.
Assuntos
Anti-Inflamatórios , Peróxido de Hidrogênio , Esteroides Heterocíclicos , Anti-Inflamatórios/síntese química , Fenômenos Químicos , Química , Oxazóis/síntese química , Compostos de Espiro/síntese química , Esteroides Heterocíclicos/síntese químicaRESUMO
Spiro[androst-4-en-17 alpha,5'-oxazolidine]-2',3,4'-trione 8a and spiro[androst-4-en-17 alpha,5'-oxazolidine]-2',3,4',11-tetraone 8b, two potentially bioactive spiranes, were prepared from the parent 17-ketones in four steps (64% and 49.5% yield, respectively). The key intermediates were the hydroxyimidates 5a and 5b, which easily underwent cyclization to the corresponding spirooxazolinone 4'-enol ethers when treated with alkylchlorocarbonates. The respective N-amyl derivatives of the spiranes 8a and 8b were obtained with n-pentyl bromide in the presence of KF. A new method for the synthesis of steroid 17 alpha-hydroxy-17-carboxyesters and 17 alpha-hydroxy-17-carboxamides is described. Attempts to synthesize the title compounds from these products were unsuccessful.
Assuntos
17-Cetosteroides , Oxazóis/síntese química , Compostos de Espiro/síntese química , Esteroides/síntese química , Estrutura MolecularRESUMO
The crystal and molecular structures of the title compounds were determined by x-ray diffractometric analysis. Torsion angles and puckering parameters are reported for both compounds. In 1 the 5 alpha-cyano group influences the A-ring conformation. The carbonate ester 3 crystallizes in the monoclinic P2(1) space group with two molecules (I and II) in the asymmetric unit. The D-ring conformation is to some extent different between I and II.
Assuntos
Androstanos/química , Androstenos/química , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Difração de Raios XRESUMO
The two histidyl-glycyl containing peptides, H(L-His-Gly)2-OH and its methyl ester (H(L-His-Gly)2-OCH3, have been structurally characterized by liquid secondary-ion mass spectrometry. Both high-internal-energy ion fragmentations produced in the source and metastable decompositions occurring in the first field-free region have been studied. The mass spectra show the presence of y-, a- and b-type ions, a1 being the most abundant fragment ion. The metastable decompositions are dominated by the loss of a water molecule and by y-type ions. The interactions of the two peptides with alkali metal ions (Li, Na, K) have been evaluated both by normal mass spectrometry and by tandem mass spectrometry to obtain selected daughter-ion spectra. The occurrence of mono-, bi- and trimetallated species has been detected in the gas phase. While, in the case of the protonated species, y-type ions are predominant, in the presence of an alkali metal ion (Cat), they show lower abundances (Cat = Li) or are absent (Cat = Na, K) both in the mass spectra produced in the source and in metastable decompositions. In most of these cases, a very intense low-internal-energy ion, which is represented by [a3 + Cat - H]+ and which can be produced by interaction of the metal with a deprotonated amide nitrogen, is recorded. This mechanism should be favored by the ¿anchoring¿ effect exerted by the imidazole ring of the histidine which promotes interaction with metals. Other metastable decompositions yield abundant [b3 + Cat - H]+ ions or involve the loss of the side-chain of the histidine. The formation of [b3 + Cat +OH]+ ions, observed only in the case of the free acid peptide, is due to the interaction of the metal ion with the C-terminus carboxyl group. Bi- and trimetallated species have also been detected in the gas phase and characterized.
Assuntos
Glicina/análise , Histidina/análise , Peptídeos/análise , Sequência de Aminoácidos , Glicina/química , Histidina/química , Hidrogênio/química , Lítio/química , Espectrometria de Massas , Metais/química , Dados de Sequência Molecular , Peptídeos/química , Potássio/química , Sódio/químicaRESUMO
Phosphate esters of vitamins D2 and D3 (D2-O-P and D3-O-P) are hydrolyzed by the alkaline phosphatase from calf intestine (CAPase). pH optimum and Km values are in agreement with those reported for other substrates for intestinal alkaline phosphatase. No effect of activation was noted at low concentrations of D2-O-P and D3-O-P (10(-5)-10(-4)M) in contrast with that stated in earlier works. At higher concentrations (1-4 mM) of the phosphorilated vitamins, accordingly with their function as substrates of CAPase, an inhibitory effect on the hydrolysis of p-nitrophenylphosphate was observed.
Assuntos
Fosfatase Alcalina/metabolismo , Colecalciferol , Ergocalciferóis , Intestinos/enzimologia , Organofosfatos , Compostos Organofosforados , Animais , Bovinos , Ativação Enzimática , Hidrólise , Nitrofenóis/metabolismo , Compostos Organofosforados/metabolismo , Fosforilação , EspectrofotometriaRESUMO
A case of occupational contact dermatitis in a female chemical pharmaceutical laboratory researcher is described. The allergological investigation revealed a state of sensitization to three mono-nitrobenzenes with halogen substitutions in the nucleus or a side chain. Problems related to sensitization to these substances and to possible cross-allergy with DNCB are discussed.
Assuntos
Dermatite de Contato/etiologia , Nitrobenzenos/efeitos adversos , Doenças Profissionais/induzido quimicamente , Tolueno/análogos & derivados , Adulto , Feminino , HumanosRESUMO
The tetrapeptide-Cu(II) complex H-(l-His-Gly)2-OH/Cu(II), indicated as L-Cu(II), has been investigated, as compared to the Cu(II) inorganic salt CuSO4, for its antioxidative and anti-inflammatory properties under a panel of experimental conditions. Both inorganic and organic Cu(II) compounds showed comparable activities in vitro and ex vivo by: (i) protecting, in a dose-dependent manner, rat brain homogenates from Fe(III)/ascorbate- or haemoglobin-induced lipid peroxidation; (ii) inhibiting the superoxide-mediated ferricytochrome c reduction by activated macrophages. CuSO4 and L-Cu(II) also exhibited similar anti-inflammatory effects in vivo by reducing significantly the extent of carrageenan-induced edema in the rat paw. The activities of the two compounds diverged strikingly only in the xanthine/xanthine oxidase system at low phosphate buffer concentration. L-Cu(II) decreased the rate of NBT reduction by superoxide in a true SOD-like fashion without affecting urate production. Instead, Cu(II) ions caused the rapid xanthine oxidase inactivation thus inhibiting both urate and superoxide production; this effect might be ascribed to the superoxide-mediated generation of the strong oxidant Cu(III) and its interaction with the enzyme. The administration of Cu(II), whether complexed with linear oligopeptides or as an inorganic salt, to animals or tissue extracts, conferred protection against oxidation and ought, conceivably, to interact with endogenous biological molecules and form highly bioavailable complexes which serve, subsequently, as the real scavengers. Moreover, the claimed prominent scavenger activities of Cu(II)-oligopeptide complexes over inorganic copper ions could be realised only in very simple in vitro systems through mechanisms which, although of biochemical interest, are unlikely to be of physiopathological significance.
Assuntos
Cobre/farmacologia , Oligopeptídeos/farmacologia , Compostos Organometálicos/farmacologia , Animais , Anti-Inflamatórios/uso terapêutico , Antioxidantes/farmacologia , Carragenina , Cátions Bivalentes/farmacologia , Córtex Cerebral/química , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Grupo dos Citocromos c/farmacologia , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Edema/tratamento farmacológico , Pé/patologia , Sequestradores de Radicais Livres/metabolismo , Cobaias , Peroxidação de Lipídeos/efeitos dos fármacos , Peróxidos Lipídicos/metabolismo , Macrófagos Alveolares/química , Macrófagos Alveolares/efeitos dos fármacos , Macrófagos Alveolares/metabolismo , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , Superóxidos/metabolismoRESUMO
Glycopeptides of hMOG(30-50) containing a glucosyl moiety on the side-chains of Asn, Ser or Hyp at position 31 were synthesised. Antibody titres to hMOG(30-50) and to its glucoderivatives were measured by ELISA in sera of patients affected by different neurological diseases. Anti-hMOG(30-50) antibodies were detected only using the glycopeptide [Asn31(N-Glc)]hMOG(30-50).