RESUMO
Four linear polyacetylenic compounds were synthesized. Pentadeca-6,8,10-triynoic acid 1 and octadeca-8,10,12-triynoic acid 2 were synthesized by using acetylene coupling reactions. The syntheses of (Z)-hexadec-11-en-7,9-diynoic acid 3 and (Z)-octadec-12-en-7,9-diynoic acid 4 by using vinylic telluride coupling reactions were accomplished.
Assuntos
Acetileno/análogos & derivados , Acetileno/síntese química , Ácidos Graxos Insaturados/síntese química , Plantas Medicinais/química , Polímeros/síntese química , Acetileno/isolamento & purificação , Alcinos , Ácidos Graxos Insaturados/isolamento & purificação , Indicadores e Reagentes , Magnoliopsida/química , Medicina Tradicional , Estrutura Molecular , Fitoterapia , Caules de Planta/química , Polímeros/isolamento & purificação , Poli-InosRESUMO
The ability of C8-substituted guanine (Gua) ribonucleosides to induce B cell proliferation has been well documented in the literature. These compounds are analogues of adducts formed from free radical attack on ribonucleosides and RNA. Here we examined the proliferative properties of two of these radical adducts, 8-methylguanosine (8-MeG) and 8-oxo-7,8-dihydroguanosine (8-OxoG) and compared them with those of the well studied B cell mitogen, 8-bromoguanosine (8-BrG). 8-MeG and 8-OxoG were synthesized in the considerable yields of 28, and 55%, respectively, and were characterized by UV, NMR and CG-MS. Their effects upon [3H]thymidine uptake into DNA by Swiss mouse splenocytes, mouse embryo 3T3 fibroblasts (A31) and mouse B16F10 melanoma were examined. Both guanosine (G) radical adducts were shown to increase [3H]thymidine uptake by mouse splenocytes but displayed selectivity in respect to continuous cell lines. 8-MeG acted upon 3T3 fibroblasts whereas 8-OxoG acted upon B16F10 melanoma. The non-physiological analogue 8-BrG acted upon all tested cells. Parallel experiments of cell counting, cytotoxicity,and cell sorting indicated that DNA synthesis induced by the C8-substituted G's reflected cell growth. It is proposed that the compounds act intracellularly because their proliferative effects were blocked in the presence of a nucleoside transport inhibitor but were not inhibited by an antagonist of the A2 purine receptor. The present results, taken together with data from the literature, suggest that in the case of 3T3 fibroblasts and mouse splenocytes the proliferative effects of the compounds are not dependent on metabolism through purine salvage pathways. In the case of melanoma, however, the compounds are likely to become part of the purine nucleoside pool. The demonstration that adducts produced by free radical attack on ribonucleosides and RNA are able to induce cell proliferation opens new perspectives for the understanding of free radical mediated carcinogenesis.
Assuntos
Guanosina/análogos & derivados , RNA/efeitos dos fármacos , Ribonucleosídeos/metabolismo , Células 3T3/citologia , Células 3T3/efeitos dos fármacos , Células 3T3/metabolismo , Adjuvantes Imunológicos/síntese química , Adjuvantes Imunológicos/farmacologia , Animais , Divisão Celular/efeitos dos fármacos , DNA/biossíntese , DNA de Neoplasias/biossíntese , Radicais Livres/metabolismo , Radicais Livres/farmacologia , Guanosina/síntese química , Guanosina/farmacologia , Masculino , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos BALB C , Mitógenos/síntese química , Mitógenos/farmacologia , RNA/metabolismo , Baço/citologia , Baço/efeitos dos fármacos , Baço/metabolismoRESUMO
The peroxidase-catalyzed aerobic oxidation of a linear aldehyde, leading to the next lower homologue in the triplet state, is accompanied by Norrish type II product ethylene when the substrate is pentanal. This system appears to provide an example of "photobiochemistry without light" because ethylene is a plant hormone and is formed in lipid peroxidation when the recurrent oxidation of linear aldehydes occurs.