Chemical Modification of Lipase and its Immobilization on Polymer Beads for Use in Organic Synthesis

A simple and effective method to produce a more active, stable and practical lipase preparation was identified. Soluble lipase from Candida rugosa was modified with different types of hydrophobic chemical modifying reagents. The esterification activities of the modified lipases were enhanced following their modification. The degree of activity enhancement depends on the type and molecular weight of the modifiers used and the degree of modification of the enzyme.A lower degree of enzyme derivatization was required for modification with the high molecular weight modifiers to attain maximal activities. In the case of monomethoxypolyethyleneglycol (PEG), however, maximal activity was attained only after exhaustive modification. The opt imum esterificat ion temperature and preference of fatty acids as acyldonors of the modified lipases were very similar to those of the native enzyme. Both were more active in non-polarsolvents than in polarsolvents. The modified lipases showed higher thermostability, solvent stability and storage stability compared to the native lipase. The lipase modified with PEG 1900 was the most thermostable, and that modified with methyl 4-phenylbutyrimidate (imidoester VI) was the most stable when incubated in benzene for ten days. The bests to rage condition was at low temperature and in the lyophilized form

Formation of stable palm kernel oil esters nanoemulsion system containing hydrocortisone

A physical and chemically stable palm kernel oil esters emulsion system with nanosized droplet was developed as a delivery system for hydrocortisone (hydrophobic drug). A simple low energy emulsification method was used in forming the nanoemulsions. The influence of added solvents (isopropanol and ethanol) on particle size and stability of oil in water nanoemulsion was investigated. Formation of nanoemulsion with solvent, increase the solubility of hydrocortisone in the oil phase and thus make the nanoemulsion more stable. Reducing the solvent to lipoid ratio showed no significant difference in the mean particle size. However, after solvent removal particle size increased over time. As for zeta potential value, all nanoemulsions exhibited values below -30 mV which indicated good stability. The DSC thermograms for stable nanoemulsions proved that hydrocortisone is in a non-crystalline state, suggesting that hydrocortisone is homogenized well in the nanoemulsion system. These results showed that nanoemulsion with solvent appear to be a promising transdermal delivery vehicle for hydrocortisone

Role of xanthan gum on physicochemical and rheological properties of rice bran oil emulsion

Xanthan gum is a high molecular weight substance with potential in improving emulsions properties. The formulation composition was selected on Tween 80 ternary phase diagram and was modified by the addition of xanthan gum at different concentrations (0.0% – 1.0%). The main objective of this study was to determine the effect of xanthan gum on physicochemical and rheological properties of rice bran oil emulsion. Xanthan gum concentrations have affected the formulations droplet size. Yet, they did not show any effect on pH of the formulations. However, an increase in xanthan gum concentration had increased the zeta potential value, stability, and viscosity of the formulations. Xanthan gum also enhanced the flow behaviour of the formulations

Optimization and kinetic study on the synthesis of palm oil ester using Lipozyme TL IM

Enzymatic synthesis of palm oil esters (POE) was carried out via alcoholysis of palm oil (PO) and oleyl alcohol (OA) catalyzed by Lipozyme TL IM. The optimum reaction conditions were: temperature: 60 °C; enzyme load: 24.7 wt%; substrate ratio: 1:3 (PO/OA), impeller speed: 275 rpm and reaction time: 3 h. At the optimum condition, the conversion of POE was 79.54%. Reusability study showed that Lipozyme TL IM could be used for 5 cycles with conversion above 50%. The alcoholysis reaction kinetic follows the Ping-Pong Bi-Bi mechanism characterized by the Vmax, Km(PO), and Km(OA) values of 32.7 mmol/min, 0.3147 mmol/ml and 0.9483 mmol/ml, respectively. The relationship between initial reaction rate and temperature was also established based on the Arrhenius law

Modeling and optimization of lipase-catalyzed production of succinic acid ester using central composite design analysis.

Esterification of succinic acid with oleyl alcohol catalyzed by immobilized Candida antarctica lipase B (Novozym 435) was investigated in this study. Response surface methodology (RSM) based on a five-level, four-variable central composite design (CCD) was used to model and analyze the reaction. A total of 21 experiments representing different combinations of the four parameters including temperature (35–65°C), time (30–450 min), enzyme amount (20-400 mg), and alcohol:acid molar ratio (1:1-8:1) were generated. A partial cubic equation could accurately model the response surface with a R2 of 0.9853. The effect and interactions of the variables on the ester synthesis were also studied. Temperature was found to be the most significant parameter that influenced the succinate ester synthesis. At the optimal conditions of 41.1°C, 272.8 min, 20 mg enzyme amount and 7.8:1 alcohol:acid molar ratio, the esterification percentage was 85.0%. The model can present a rapid means for estimating the conversion yield of succinate ester within the selected ranges

Characterization of structural stability of palm oil esters-based nanocosmeceuticals loaded with tocotrienol

Background: Palm oil esters (POEs) are esters derived from palm oil and oleyl alcohol have great potential in the cosmetic and pharmaceutical industries due to the excellent wetting behavior of the esters without the oily feel. The role of oil-in-water nanoemulsions loaded with tocotrienol sedimentation behavior was studied. LUMiFuge® 116 particle separation analyzer was used to investigate the sedimentation behavior of POEs/tocotrienol/xanthan gum nanoemulsion system during centrifugation. Analyzing the sedimentation kinetics of dispersions in a centrifugal field also yields information about the rheological behavior and structural stability.Methods: Experiments were performed in an analytical centrifuge at 11×g to 1140×g (LUMiFuge® 116 particle separation analyzer). The samples in the LUMiFuge® 116 particle separation analyzer were centrifuged at 3000 rpm for 15 h at 32°C. Sample volume of 2 cm3 was used. The rheological property of nanoemulsions was investigated using oscillatory measurements test. A rotational/oscillatory viscometer, Kinexus Rheometer (Malvern Instrument, UK) was used. All measurements were performed with a stainless steel cone-plate sensor at 25.0 ± 0.1°C with 4°/40 mm.Results: The stable nanoemulsions showed sedimentation rates at earth gravity of 5.2, 3.0 and 2.6 mm/month for 10%, 20% and 30% (w/w) oil phase, respectively. Rheological behavior is an important target during the design of palm oil esters-based nanocosmeceuticals. The presence of a network structure was indicated by measurements which showed G' to be greater than G" This result implied the predominant elastic response and high storage stability of the nanoemulsion. It was also observed that the increase in oil phase concentration led to the profile which strongly indicated that the solid like elastic property; where the values of phase angle, δ of these nanoemulsions was lower than 45°.Conclusions: The nanoemulsions with higher oil phase concentration (30% (w/w)) showed greater elasticity which implied strong dynamic rigidity of the nanoemulsion. It was the most stable with longest shelf-life