ABSTRACT
Three new isoaigialones, A, B, and C (1-3), along with aigialone (4), were isolated from the crude EtOAc extract of a Phaeoacremonium sp., an endophytic fungus obtained from the leaves of Senna spectabilis. The structures of these compounds were elucidated based on the analysis of spectroscopic data. Compounds 2 and 4 were active against the phytopathogenic fungi Cladosporium cladosporioides and C. sphaerospermum. This is the first report of metabolites produced by an Phaeoacremonium sp., associated with S. spectabilis.
Subject(s)
Acetals/isolation & purification , Acetals/pharmacology , Antifungal Agents/isolation & purification , Antifungal Agents/pharmacology , Ascomycota/chemistry , Cladosporium/chemistry , Ketones/isolation & purification , Ketones/pharmacology , Lactones/isolation & purification , Plant Leaves/chemistry , Senna Plant/chemistry , Acetals/chemistry , Antifungal Agents/chemistry , Ketones/chemistry , Lactones/chemistry , Lactones/metabolism , Lactones/pharmacology , Molecular StructureABSTRACT
Lipases are versatile enzymes regarding the range of reactions they catalyse and substrates on which they act. They are as well important as catalyst in organic synthesis. Their immobilization on appropriate supports confer them greater stability besides the possibility of operating in continuous reactors. In order to explore these abilities, the reactions involving hydrolysis of p-nitrophenyl acetate (PNPA) and transesterification of PNPA with n-butanol were chosen. Lipases from two different sources were assayed, namely: microbial (Candida rugosa, CRL, Sigma Type VII) and pancreatic (PPL, Sigma, Type II). Two immobilization methods were also used, namely: 1). adsorption, using as support the following silica derivatives (150-300 microm e 450micro): phenyl, epoxy, amino and without derivation, and 2). covalent binding, using glutaraldehyde as binding agent and silica amino as support. This later method led to better results. Hydrolytic activity was 6.1 U/g(support) for CRL and 0.97 U/g(support) for PPL, and of transesterification, 2,8 U/g(support) for CRL and 1,9 U/g(support) for PPL. Stability of the immobilized enzyme as a function of temperature was evaluated for CRL at 40 degrees C and 50 degrees C and for PPL at 32 degrees C and 40 degrees C. The assays were initially carried out batchwise, both for soluble and immobilized enzymes, aiming to the obtention of parameters for the continuous reactor. Lipases immobilized by covalent binding were used in the assays of operational stability in continuous reactors. For PPL in aqueous medium, at 32 degrees C, and CRL in organic medium at 40 degrees C, both operating continuously, no significant loss of activity was detected along the analysis period of 17 days. In the case of CRL in aqueous medium at 40 degrees C there was a loss of activity around 40% after 18 days. For PPL in organic medium at 40 degrees C the loss was 33% after 20 days. Comparing both sources with each other, very different results were obtained. Higher activity was found for CRL, both for hydrolysis and for transesterification reactions, with higher stability in organic medium. PPL showed lower activity as well as higher stability in aqueous medium. The immobilization method by covalent binding showed to be the most appropriate. Immobilized lipases are therefore relatively stable both in aqueous and organic medium.
Subject(s)
Bioreactors , Enzymes, Immobilized/metabolism , Lipase/metabolism , Adsorption , Animals , Candida , Desiccation , Enzyme Stability , Glutaral , Lipase/chemistry , Silicon Dioxide , Swine , Temperature , Time FactorsABSTRACT
No presente trabalho apresenta-se um método de cristalizaçäo da papaína oriunda do látex fresco de mamäo, o qual apresenta uma alta produtividade em relaçäo aos métodos previamente descritos. A metodologia aqui descrita näo envolve o uso de reagentes sulfídrilicos, a papaína foi obtida de forma praticamente pura, apresentando uma simples banda quando submetida a eletroforese, e com propriedades idênticas àquelas obtidas por outros métodos. A atividade específica foi determinada utilizando Z-gly-pNP e BAEF como substrato. A papaína obtida por essa metodologia, sem uso de substâncias tais como cisteína e ditiotreitol, apresenta-se na forma de um complexo com inibidores naturais, os quais podem ser removidos por diálise
Subject(s)
Food Technology , Crystallization , Cysteine , Dithiothreitol , Electrophoresis , PapainABSTRACT
Macroporous silica gel, prepared from sodium silicate and hydrochloric acid, one grade of diatomaceous earth (celite 545) and nonporous glass were analyzed in terms of pore size by the mercury intrusion pressure method. The alkylamine derivatives of the above materials were examined for their suitability as supports for enzyme immobilization, using the enzyme glucose oxidase. The effectiveness of the immobilized enzyme was compared in relation to the free enzyme and particle size of the carier. The immobilized enzyme exhibited a broader range of optimum pH and greater thermal stability, among some properties considered
