RESUMO
It has been hypothesized that the therapeutic effects of artepillin C, a natural compound derived from Brazilian green propolis, are likely related to its partition in the lipid bilayer component of biological membranes. To test this hypothesis, we investigated the effects of the major compound of green propolis, artepillin C, on model membranes (small and giant unilamelar vesicles) composed of ternary lipid mixtures containing cholesterol, which display liquid-ordered (lo) and liquid-disordered (ld) phase coexistence. Specifically, we explored potential changes in relevant membrane parameters upon addition of artepillin C presenting both neutral and deprotonated states by means of small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and confocal and multiphoton excitation fluorescence microscopy. Thermotropic analysis obtained from DSC experiments indicated a loss in the lipid cooperativity of lo phase at equilibrium conditions, while at similar conditions spontaneous formation of unilamellar vesicles from SAXS experiments showed that deprotonated artepillin C preferentially located at the surface of the membrane. Time-resolved experiments using fluorescence microscopy showed that at doses above 100 µM, artepillin C in its neutral state interacted with both liquid-ordered and liquid-disordered phases, inducing curvature stress and promoting dehydration at the membrane interface.
Assuntos
Fenilpropionatos/química , Bicamadas Lipídicas/química , Lipossomos/química , Valores de Referência , Temperatura , Fatores de Tempo , Varredura Diferencial de Calorimetria , Colesterol/química , Reprodutibilidade dos Testes , Microscopia Confocal , Espalhamento a Baixo Ângulo , Lauratos , Microscopia de Fluorescência , Modelos Químicos , 2-Naftilamina/análogos & derivadosRESUMO
(R)-2-hydroxy-3-phenylpropionic acid (PLA) is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate (PPA) to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6:4, 40 °C, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/ n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor (2-L scale). Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.
Assuntos
Soluções Tampão , Escherichia coli/metabolismo , L-Lactato Desidrogenase/metabolismo , Microrganismos Geneticamente Modificados , Octanos/química , Fenilpropionatos/química , Proteínas Recombinantes/química , Solventes/química , Estresse Mecânico , TemperaturaRESUMO
The esterification of phenylpropanoid and hydrophenylpropanoid acids, catalyzed by candida antarctica lipase B (CAL-B), with several alcohols has demonstrated that the substitution pattern on the aromatic ring has a very significant influence on the reactivity of the carboxyl group due, mainly, to electronic effects, when compared to the unsaturated acids with the hydrogenated acids. It is also clear that in the saturated acids there still remain some unclear effects related to the aromatic substituents.
Assuntos
Esterificação , Fenilpropionatos/metabolismo , Lipase/metabolismo , Catálise , Cromatografia Líquida de Alta Pressão , Candida/enzimologia , Enzimas Imobilizadas/metabolismo , Enzimas Imobilizadas/química , Fenilpropionatos/química , Lipase/química , SolventesRESUMO
El gamma-Oryzanol, una mezcla de ésteres del ácido ferúlico de esterol y alcohol triterpénico, está presente en el aceite de salvado de arroz en niveles que varían entre 1-2 g/100g, donde actúa como antioxidante natural. Recientes investigaciones han demostrado que el gamma-Oryzanol causa una disminución en el nivel de colesterol en las arterias, reduciendo el riesgo de enfermedades cardiovasculares, además, también ha sido usado en Japón como antioxidante natural en alimentos, bebidas y cosméticos. Esta revisión aborda los aspectos referentes al gamma-Oryzanol, como sus propiedades físico-químicas, su presencia en el aceite de salvado de arroz, su actividad antioxidante e hipocolesterolémica, asé como los métodos de extracción, identificación y cuantificación.