Biocatalysis using lipase encapsulated in microemulsion-based organogels in supercritical carbon dioxide

This article has been published in the journal, The Journal of Supercritical Fluids [© Elsevier]. The definitive version is available at http://dx.doi.org/10.1016/j.supflu.2005.06.007Journal URL: http://www.sciencedirect.com/science/journal/0896844

Inducing the formation of a colloidal albumin carrier of curcumin

The administration and delivery of pharmaceuticals faces a variety of well-known obstacles that result in limited biocompatibility and bioavailability. Efforts to improve these properties have often employed serum albumin, primarily due to its inherent biocompatibility and its ability to enhance the circulation times of pharmaceuticals. In this work, we have adapted a nanoparticle-formulation protocol, to produce a protein carrier of curcumin with bovine serum albumin. This was achieved by using a near-equimolar protein:curcumin ratio instead of the abundance of curcumin that would be normally used in a nanoparticle formulation. Photometric and quantitative analysis of this carrier showed an increased curcumin content in the produced aqueous solutions following the homogenization of bovine serum albumin (water) and curcumin (dichloromethane) phases. Albumin fluorescence studies indicated curcumin association near a tryptophan residue, without excluding the possibility of additional sites. Circular dichroism provided strong evidence of this association through the induced circular dichroism effect and showed that the secondary structure of bovine serum albumin was effectively maintained. Overall, this work presented a new means of facilitating the association of increased levels of curcumin with bovine serum albumin, which could potentially be used to generate additional non-covalent albumin carriers for pharmaceutical compounds. © 2022 The Author

Catalytic reactivity of the complexes [Pd(Ph2P)2N(tBu)-P,P´X2], X = Cl, Br, I, in the Suzuki-Miyaura C−C coupling reaction: Probing effects of the halogeno ligand X− and the ligand’s tBu group

The synthesis, as well as the spectroscopic and structural characterization of three analogous palladium(II) complexes, [Pd(Ph2P)2N(tBu)-κ2P,P´X2], X = Cl, Br, I, is presented. X-ray crystallography studies revealed a similar square planar PdP2X2 first coordination sphere among the three complexes. The catalytic reactivity of these complexes was tested in the Suzuki-Miyaura coupling reaction, showing that the X = Cl, Br, complexes are more active than the X = I analogue. The differences in the catalytic reactivity within this series of complexes, as well as comparisons with similar palladium(II) catalysts reported in the literature, are discussed with respect to the different electronegativity of the three halogens and the strong +I inductive effect of the ligand’s tBu group. © 2018 Elsevier B.V

Enzymatic modification of triglycerides in conventional and surfactant-free microemulsions and in olive oil

Modification of the acylglycerol profile by interesterification of triacyglycerols (TAGs) can improve certain properties of food products. TAGs enriched in palmitic acid (PA) at the sn-2 position and in unsaturated fatty acids at the sn-1,3 position of the glycerol backbone are an important source of nutrients and energy for humans. In the present study, commercially available lipases have been used for the enzymatic interesterification of TAGs to form lipids containing PA and oleic acid (OA). Lipases A and B from Candida antarctica (CaL A and CaL B) and Thermomyces lanuginosus lipase (TLL) were tested in different environments from organic solvents to non-conventional systems such as w/o microemulsions (in the absence and presence of surfactants) and olive oil. The effects of reaction temperature, substrate molar ratio, and external energy were investigated. AOT microemulsions offered an excellent microenvironment for the interesterification reaction, while lecithin microemulsion affected TLL specificity. Surfactant-free microemulsions were also tested in terms of optimization of production process, however lower reaction yields were obtained. For the commercial immobilized CaL B, the ratio PA:triolein affected the reaction yield with the 2:1 ratio showing promising results in organic solvent environment. The main purpose of the present study was to elucidate the appropriate conditions for the enzymatic modification of olive oil. Several factors were tested such as substrates’ ratio, enzyme's concentration, reaction temperature and external energy input. Overall, the ideal conditions for the formulation of the desired TAGs included the use of 50 mM free PA as substrate, 3 mg of immobilized CaL B/mL of olive oil while the reaction temperature was set at 40 °C and the duration was 72 h. © 2022 Elsevier B.V

Nanoencapsulated Lecitase Ultra and <i>Thermomyces lanuginosus</i> Lipase, a Comparative Structural Study

Two commercially available and widely used enzymes, the parent <i>Thermomyces lanuginosus</i> lipase (TLL) and the shuffled phospholipase A1 Lecitase (Lecitase Ultra), were encapsulated in AOT/isooctane reverse micelles and evaluated regarding their structure and activity. Preparations were also tested as effective biocatalysts. Small-angle X-ray scattering (SAXS), electronic paramagnetic resonance (EPR), and fluorescence spectroscopy were the techniques applied to assess the effects of enzyme incorporation to a reverse micellar nanostructure. SAXS analysis showed that the radius of gyration (<i>R</i>_g) changed from 16 to 38 Å, as the water content (<i>w</i>₀) increased. Elongated shapes were more commonly observed than spherical shapes after enzyme encapsulation. EPR studies indicated that enzymes do not participate in the interface, being located in the aqueous center. Fluorescence energy transfer showed that TLL is located in the water core, whereas Lecitase Ultra is closer to the interface. Enzymatic activity toward a standard esterification reaction endured after the enzyme was incorporated into the micelles. The activity of TLL for systems with <i>w</i>₀ 15 showed the highest conversion yield, 38% in 2 h, while the system with <i>w</i>₀ 10 showed the highest initial velocity, 0.43 μM/min. This last system had a <i>R</i>_g of 19.3 Å, similar to that of the TLL monomer. Lecitase Ultra showed the highest conversion yields in systems with <i>w</i>₀ 10, 55% in 2 h. However, the initial rate was much lower than that of TLL, suggesting less affinity for the substrates, which is expected since Lecitase Ultra is a phospholipase. In summary, we here used several spectroscopic and scattering techniques to reveal the shape and stability of TTL and Lecitase Ultra encapsulated systems, which allowed the selection of <i>w</i>₀ values to provide optimized enzymatic activity