RESUMO
Oblongifolins A-D (2-5), four new polyprenylated 3,4-dihydroxybenzoylphloroglucinol compounds, were isolated from the bark of Garcinia oblongifolia collected in Vietnam. The bark was also found to contain the known compounds camboginol and guttiferone B. Extraction of the leaves gave 2 and camboginol. Details of the structure elucidation of 2-5 and stereochemical comparisons with known natural derivatives of general formula 1a,b are presented. The biological activity of these compounds concerning interactions with tubulin was investigated.
Assuntos
Garcinia/química , Floroglucinol , Plantas Medicinais/química , Estrutura Molecular , Floroglucinol/análogos & derivados , Floroglucinol/química , Floroglucinol/isolamento & purificação , Floroglucinol/farmacologia , Casca de Planta/química , Folhas de Planta/química , Terpenos/isolamento & purificação , Tubulina (Proteína)/efeitos dos fármacos , VietnãRESUMO
The one-step glycosylation of arylamines in acidic medium is extended to adenine derivatives for the first time, providing a considerable improvement over existing reactions. This method is used to prepare some rhamnospicamycin analogues containing different base moieties. Results suggest that this novel approach will be applicable to a wide range of carbohydrates and arylamines, possibly leading to a combinatorial library of analogues of spicamycin for the better understanding of the modes of action of this antitumour antibiotic family.
Assuntos
Antineoplásicos/síntese química , Nucleosídeos de Purina/síntese química , Antineoplásicos/química , Glicosilação , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Nucleosídeos de Purina/químicaRESUMO
Monolayers of lipid derivatives of colchicine spread at the air--water interface reach the thermodynamic equilibrium over an abnormally long period of time. Dynamics of this equilibration and the behavior of the film during compression--decompression cycles are observed by fluorescence microscopy. The thermodynamically disfavored structures observed are unrelated to previously described unusual shapes in the liquid expanded-gas coexistence regions. The relation between the cholesterol-like effect of the colchicinoid moiety, its propensity to dimerize, and the high viscosity of the monolayer are discussed.
Assuntos
Colchicina/química , Lipídeos/química , Micelas , Dimerização , Corantes Fluorescentes , Microscopia de Fluorescência , Estrutura Molecular , Fosfatidiletanolaminas , Relação Estrutura-Atividade , Propriedades de Superfície , Termodinâmica , ViscosidadeRESUMO
Dinucleoside polyphosphates are ubiquitous compounds tightly involved in the regulation of a number of key biological processes. Hydrolysis-resistant analogues of Ap(3)A and Gp(3)G, two important members of that family of nucleotides, have been synthesized. P(1),P(2):P(2),P(3)-Bis-methylene diadenosine and diguanosine triphosphates were prepared from O,O-dialkyl methaneselenophosphonates using an original methodology. Whereas the 2-fold addition of the methanephosphonate anion to the activated phosphorus species cannot be performed, multiple condensation of lithiated methaneselenophosphonate with electrophilic trivalent phosphorus compounds is revealed to be very effective. A one-pot condensation/esterification/oxidation sequence involving O,O-dialkyl methaneselenophosphonates provides a highly efficient route to the PCH(2)PCH(2)P backbone. This new development in selenophosphonate chemistry offers a great potential for further regioselective functionalization of polyphosphate mimics.
