Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

Influence of Chemical Modifications of Polyhydroxyalkanoate-Derived Fatty Acids on Their Antimicrobial Properties

Sugar esters are bioactive compounds derived from renewable resources. They consist of a sugar moiety with attached non-polar part – usually a fatty acid. These compounds find uses in cosmetic, food and pharmaceutical industries as surfactants due to their physicochemical and antimicrobial activities. In this study we have produced fatty acids for sugar ester synthesis from bacterially derived polyesters, namely polyhydroxyalkanoates (PHAs). We have developed methodology to decorate PHA monomers with a fluorinated moiety. With aid of biocatalysis a series of glucose esters was created with unmodified and modified PHA monomers. All synthesised compounds showed moderate antimicrobial activity.

PLACKETT–BURMAN DESIGN AS A TOOL FOR SCREENING AND PROCESS OPTIMIZATION OF RIVASTIGMINE-LOADED LIPID NANOCARRIERS

Objective: Plackett–Burman experimental design is used to identify the most important factors early in the experimentation phase when complete knowledge about the system is usually unavailable. The objective of this study was to screen out the most important factors affecting the size and entrapment efficiency of rivastigmine hydrogen tartrate (RHT) nanostructured lipid carriers (NLCs).Methods: The RHT-loaded NLC was prepared by the modified solvent emulsification-diffusion method. The independent variables selected for Plackett–Burman design were drug: lipid ratio, solid lipid/liquid lipid (S/L) ratio, concentration Ryoto sugar ester (%w/v), the concentration of poloxamer 188 (%w/v), sonication time (min), sonication amplitude, and stirring time (h).Results: The R2 value for the particle size equation was 86.16%. p value was (<0.05) 0.048 in case of sonication time. In case of entrapment efficiency, the R2 value was 87.12%. The p value (p<0.05) for S/L ratio and the Ryoto sugar (% w/v) was 0.028 and 0.042, respectively.Conclusion: It can be concluded that sonication time has a significant effect on particle size, whereas S/L ratio and Ryoto sugar ester concentration have a significant effect on entrapment efficiency.