Encapsulation of eugenyl acetate in PHBV using SEDS technique and in vitro release evaluation.

Eugenyl acetate obtained via enzymatic esterification using Lipozyme TL IM enzyme was encapsulated in biopolymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) through solution-enhanced dispersion by supercritical fluids (SEDS). Produced particles were characterized by SEM and confocal microscopy techniques and in addition in vitro release assays were performed in isopropanol and ethyl acetate. Experimental micronization conditions comprised 8 and 10 MPa, 308 and 313 K and eugenyl acetate concentration ranging from 5 to 20 mg mL-1, keeping PHBV concentration constant (20 mg mL-1 in dichloromethane). The maximum encapsulation efficiency was 58.0 % for 5 mg mL-1of eugenyl acetate at 8 MPa and 308 K. The morphology of the encapsulated particles for most of the trials was spherical, with particle size ranging from 0.061 to 0.276 µm. Regarding the release in ethyl acetate and isopropanol solvents the higher the affinity of the encapsulated ester of these solvents, the faster the release was observed. These results demonstrate the importance of essential clove oil esterification reaction and encapsulation of the ester by SEDS method so that this encapsulated ester can be used in different industrial applications.

A review on lipase-catalyzed reactions in ultrasound-assisted systems.

The named "green chemistry" has been receiving increasing prominence due to its environmentally friendly characteristics. The use of enzymes as catalysts in processes of synthesis to replace the traditional use of chemical catalysts present as main advantage the fact of following the principles of the green chemistry. However, processes of enzymatic nature generally provide lower yields when compared to the conventional chemical processes. Therefore, in the last years, the ultrasound has been extensively used in enzymatic processes, such as the production of esters with desirable characteristics for the pharmaceutical, cosmetics, and food industry, for the hydrolysis and glycerolysis of vegetable oils, production of biodiesel, etc. Several works found in the open literature suggest that the energy released by the ultrasound during the cavitation phenomena can be used to enhance mass transfer (substrate/enzyme), hence increasing the rate of products formation, and also contributing to enhance the enzyme catalytic activity. Furthermore, the ultrasound is considered a "green" technology due to its high efficiency, low instrumental requirement and significant reduction of the processing time in comparison to other techniques. The main goal of this review was to summarize studies available to date regarding the application of ultrasound in enzyme-catalyzed esterification, hydrolysis, glycerolysis and transesterification reactions.

Lipozyme TL IM as Catalyst for the Synthesis of Eugenyl Acetate in Solvent-Free Acetylation.

The ability of commercial immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM) to catalyze the acetylation of essential clove oil with acetic anhydride in a solvent-free system was studied, and the antimicrobial activity of the ester formed was evaluated as well. Experimental design based on two variables (eugenol to acetic anhydride molar ratio and temperature) was employed to evaluate the experimental conditions of eugenyl acetate ester production. The maximum conversion yield (92.86 %) was obtained using Lipozyme TL IM (5 wt%, based on the total amount of substrates), with eugenol to acetic anhydride molar ratio of 1:5 at 70 °C. The chemical structure of the eugenyl acetate ester obtained at the optimized condition, and purified, was confirmed by the proton nuclear magnetic resonance ((1)H-NMR) analysis. The antimicrobial activity of eugenyl acetate ester was proven effective on Gram-positive and Gram-negative bacteria, with means of 16.62 and 17.55 mm of inhibition halo.