RESUMEN
This work aimed to define strategies to increase the bioproduction of 6 pentyl-α-pyrone (bioaroma). As first strategy, fermentations were carried out in the solid state, with agro-industrial residues: Mauritia flexuosa Liliopsida. and Manihot esculenta Crantz in isolation, conducting them with different nutrient solutions having Trichoderma harzianum as a fermenting fungus. Physicochemical characterizations, centesimal composition, lignocellulosic and mineral content and antimicrobial activity were required. Fermentations were conducted under different humidification conditions (water, nutrient solution without additives and nutrient solutions with glucose or sucrose) for 9 days. Bioaroma was quantified by gas chromatography, assisted by solid-phase microextraction. The results showed the low production of this compound in fermentations conducted with sweet cassava (around 6 ppm (w/w)). The low bioproduction with sweet cassava residues can probably be related to its starch-rich composition, homogeneous substrate, and low concentration of nutrients. Already using buriti, the absence of aroma production was detected. Probably the presence of silicon and high lignin content in buriti minimized the fungal activity, making it difficult to obtain the aroma of interest. Given the characteristics presented by the waste, a new strategy was chosen: mixing waste in a 1:1 ratio. This fermentation resulted in the production of 156.24 ppm (w/w) of aroma using the nutrient solution added with glucose. This combination, therefore, promoted more favorable environment for the process, possibly due to the presence of fermentable sugars from sweet cassava and fatty acids from the buriti peel, thus proving the possibility of an increase of around 2500% in the bioproduction of coconut aroma.
Asunto(s)
Manihot , Pironas , Manihot/química , Manihot/metabolismo , Pironas/metabolismo , Pironas/química , Cocos/química , Odorantes/análisis , Hypocreales/metabolismo , FermentaciónRESUMEN
Immobilization of Zymomonas mobilis by different methods was investigated. Experiments were performed in order to choose the most appropriate support for the immobilization of the cells. The most advantageous option was to use permeabilized cells in the bore of microporous hollow fibers. Whereas the reaction rate was about 33 g of gluconate/(g of protein x h) using hollow fibers, which is comparable to that observed by using free cells, the calcium alginate immobilized cells presented a reaction rate of 4 g of gluconate/(g of protein x h). These results can be explained by the mass transfer resistance effect, which, indeed, was much lower in the case of hollow-fiber membranes than in the alginate gel beads. A loss of enzymatic activity during the reaction was observed in all experiments, which was attributed to the lactone produced as an intermediate of the reaction.
Asunto(s)
Células Inmovilizadas/metabolismo , Gluconatos/metabolismo , Sorbitol/metabolismo , Zymomonas/metabolismo , Alginatos , Biotecnología/instrumentación , Biotecnología/métodos , Permeabilidad de la Membrana Celular , Ácido Glucurónico , Ácidos Hexurónicos , Cinética , Membranas ArtificialesRESUMEN
Binding and localization of the vasodilator and antitumor drug coactivator dipyridamole (DIP) and of its three derivatives, RA14, RA47 and RA25 (DIPD), to cationic (cetyltrimethylammonium chloride), anionic (sodium dodecylsulfate), zwitterionic (N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate), and neutral (t-octylphenoxypolyethoxyethanol) micelles was studied using fluorescence, optical absorption and 1H NMR spectroscopy. The analysis of NMR, optical absorption and fluorescence data indicates that the depth of localization of the drugs in the micelles from the surface decreased in the order DIP > RA14 > RA47 > RA25. The binding constants for the neutral drug forms change in the same order in the range of 1400-3100 M-1 for DIP to 80-300 M-1 for RA25. This order is identical with the reported biological activity of DIPD. For the protonated drugs in zwitterionic or neutral micelles the binding constants are reduced by a factor of 20-75.
Asunto(s)
Dipiridamol/análogos & derivados , Dipiridamol/química , Micelas , Vasodilatadores/química , Sitios de Unión , Espectroscopía de Resonancia Magnética , Estructura Molecular , Soluciones , Espectrometría de Fluorescencia , Espectrofotometría , Relación Estructura-ActividadRESUMEN
The localization of the coronary vasodilator dipyridamole (DIP) in cationic cetyltrimethylammonium chloride (CTAC), anionic sodium dodecylsulfate (SDS) and zwitterionic N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and lysophosphatidylcholine (HPS and LPC) micelles was investigated using fluorescence quenching by quenchers with known localization in the micelle (TEMPO and 5-doxyl and 12-doxyl stearic acids). The use of fluorescence quenching jointly with fluorescence and 1H-NMR spectral measurements shows that DIP molecules in both protonated and nonprotonated forms are localized in micelles near the region which separates their polar and nonpolar parts, the polarizable heteroaromatic cycle of DIP being close to the polar part and the nonpolar substituents penetrating the hydrophobic interior of the micelle. The electrostatic interaction between the protonated DIP molecules and micelle charges either moves DIP into the micelle interior (for cationic and zwitterionic micelles) or draws it closer to the micelle surface (for anionic ones). Our results could be relevant to the mechanism of DIP action since many data indicate the interaction of the drug with cell membranes. The ability of DIP to localize near the membrane surface with the substituents immersed into a hydrophobic moiety could be essential for the drug interaction with P-glycoprotein, which is responsible for mediation of the effects of several antitumour drugs.