Nonlinear Flux-Pressure Behavior of Solvent Permeation through a Hydrophobic Nanofiltration Membrane.

Nonpolar solvents have been reported to exhibit a nonlinear flux-pressure behavior in hydrophobic membranes. This study explored the flux-pressure relationship of six nonpolar solvents in a lab-cast hydrophobic poly(dimethylsiloxane) (PDMS) membrane and integrated the permeance behavior in the evaluation of the proposed transport model. The solvents exhibited a nonlinear relationship with the applied pressure, along with the point of permeance transition (1.5-2.5 MPa), identified as the critical pressure corresponding to membrane compaction. Two classical transport models, the pore-flow model and solution-diffusion model, were evaluated for the prediction of permeance. The solution-diffusion model indicated a high correlation with the experimental results before the point of transition (R 2 = 0.97). After the point of transition, the compaction factor (due to membrane compaction after the critical pressure) derived from the permeance characteristics was included, which significantly improved the predictability of the solution-diffusion model (R 2 = 0.91). A nonlinear flux-pressure behavior was also observed in hexane-oil miscella (a two-component system), confirming the existence of a similar phenomenon. The study revealed that a solution-diffusion model with appropriate inclusion of compaction factor could be used as a prediction tool for solvent permeance over a wide range of applied transmembrane pressures (0-4 MPa) in solvent-resistant nanofiltration (SRNF) membranes.

Ionic liquid-based microwave-assisted extraction of Heneicos-1-ene from coriander foliage and optimizing yield parameters by response surface methodology.

In this study, an efficient ionic liquid (IL)-based microwave-assisted extraction (IL-MAE) was employed for the extraction of Heneicos-1-ene from coriander foliage. Quantification of Heneicos-1-ene was carried out using high-performance liquid chromatography. Parameters affecting extraction such as material to solvent ratio (1:10, 1:15, and 1:20), types of IL ([CH3(CH2)3]4NF, [BMIM][PF6], [BMIM][BF4], and [C6H5]4P[Br]), concentration of IL (0.1, 0.5, and 1.0 M), microwave power (200, 500, and 800 W), extraction temperature (50, 70, and 90 °C) and extraction time (2, 6, and 10 min) were evaluated. Response surface methodology was applied to determine the optimum levels of these parameters to get maximum yield. The optimal conditions were achieved at 800 W, 90 °C for 2 min at a material to solvent ratio of 1:10 using 0.1 M solution of [BMIM][BF4], to get maximum predicted yield of Heneicos-1-ene (412.8 mg/100 g) as against 408.5 ± 1.14 mg/100 g for experimental value with 0.991 correlation coefficient. IL-MAE resulted in 5.85 times higher yield as compared to the conventional method (69.77 ± 1.8 mg/100 g).

Solubility of caffeine from green tea in supercritical CO2: a theoretical and empirical approach.

Decaffeination of fresh green tea was carried out with supercritical CO2 in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO2 varied from 44.19 × 10(-6) to 149.55 × 10(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO2 was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 × 10(-3) mol fraction was obtained with chloroform.

Culture Conditions for Production of Biomass, Adenosine, and Cordycepin from Cordyceps sinensis CS1197: Optimization by Desirability Function Method.

BACKGROUND: Cordyceps sinensis (CS) is a traditional Chinese medicine contains potent active metabolites such as nucleosides and polysaccharides. The submerged cultivation technique is studied for the large scale production of CS for biomass and metabolites production. OBJECTIVE: To optimize culture conditions for large-scale production of CS1197 biomass and metabolites production. MATERIALS AND METHODS: The CS1197 strain of CS was isolated from dead larvae of natural CS and the authenticity was assured by the presence of two major markers adenosine and cordycepin by high performance liquid chromatography and mass spectrometry. A three-level Box-Behnken design was employed to optimize process parameters culturing temperature, pH, and inoculum volume for the biomass yield, adenosine and cordycepin. The experimental results were regressed to a second-order polynomial equation by a multiple regression analysis for the prediction of biomass yield, adenosine and cordycepin production. Multiple responses were optimized based on desirability function method. RESULTS: The desirability function suggested the process conditions temperature 28°C, pH 7 and inoculum volume 10% for optimal production of nutraceuticals in the biomass. The water extracts from dried CS1197 mycelia showed good inhibition for 2 diphenyl-1-picrylhydrazyl and 2,2-azinobis-(3-ethyl-benzo-thiazoline-6-sulfonic acid-free radicals. CONCLUSION: The result suggests that response surface methodology-desirability function coupled approach can successfully optimize the culture conditions for CS1197. SUMMARY: Authentication of CS1197 strain by the presence of adenosine and cordycepin and culturing period was determined to be for 14 daysContent of nucleosides in natural CS was found higher than in cultured CS1197 myceliumBox-Behnken design to optimize critical cultural conditions: temperature, pH and inoculum volumeWater extract showed better antioxidant activity proving credible source of natural antioxidants.

Catechin concentrates of garden tea leaves (Camellia sinensis L.): extraction/isolation and evaluation of chemical composition.

BACKGROUND: Solid-liquid (SLE) and liquid-liquid (LLE) extraction techniques were applied to extract catechins and caffeine from quick mechanically expelled tea leaf juice (QMETLJ) and freeze-dried (FD)-QMETLJ of Camellia sinensis L. The concentrates obtained were analyzed for total polyphenol content and antioxidant activity (DPPH(•) inhibition, FRAP and phosphomolybdenum assay). Catechins were identified and quantified using HPLC. RESULTS: Overall, 95% (v/v) ethanol was the best solvent system for extracting total polyphenols (355.26 ± 23.68 to 457.89 ± 28.94 g GAE kg(-1) extractable solid yield (ESY)) and antioxidants (DPPH(•) inhibition, 16.97 ± 0.52 to 20.83 ± 3.11%; FRAP, 4.15 ± 0.32 to 6.38 ± 0.57 mmol TE g(-1) ESY; Mo(V) reduction, 2.47 ± 0.19 to 3.84 ± 0.39 mmol AAE g(-1) ESY) from FD-QMETLJ. Similarly, in LLE, ethyl acetate showed the best results for recovering polyphenols (960.52 ± 7.89 g GAE kg(-1) ESY) and antioxidants (DPPH(•) inhibition, 42.39 ± 0.91%; FRAP, 11.39 ± 0.83 mmol TE g(-1) ESY; Mo(V) reduction, 6.71 ± 1.14 mmol AAE g(-1) ESY) from QMETLJ. CONCLUSION: It was found that 95% ethanol can be used to increase the total polyphenols and antioxidants in extracts from FD-QMETLJ, while ethyl acetate can be effectively employed for concentrating catechins from QMETLJ.

Engineering liposomes of leaf extract of seabuckthorn (SBT) by supercritical carbon dioxide (SCCO2)-mediated process.

Seabuckthorn (SBT; Hipphophae rhamnoides) leaf extract obtained by supercritical carbon dioxide (SCCO(2)) using ethanol as an entrainer, containing mainly flavanoids as bioactive principles with antioxidant and antibacterial properties, was used for the preparation of liposomes. Liposomes are promising drug carriers with sustained release because they can enhance the membrane penetration of drugs, deliver the entrapped drugs across cell membranes, and improve extract stability and bioavailability. The aim of the present study was to compare the two different methods of liposome production: the Bangham thin-film method and SCCO(2) gas antisolvent method (SCCO(2) GAS) for the incorporation of SBT leaf extract in terms of particle size, morphology, encapsulation efficiency, antioxidant activity, and thermal stability. Liposomes obtained with the thin-film method were multilamellar vesicles with average particle size (3,740 nm), encapsulation efficiency (14.60%), and particle-size range (1.57-6.0 µm), respectively. On the other hand, liposomes by the SCCO(2) GAS method were nanosized (930 nm) with an improved encapsulation efficiency (28.42%) and narrow range of size distribution (0.48-1.07 µm), respectively. Further, the antioxidant activity of leaf extract of SBT was determined by the 2 diphenyl-1-picrylhydrazyl method and expressed as Trolox equivalents as well as of the intercalated extract in liposomes. The oxidative stability of SBT encapsulated in liposomes was again estimated using differential scanning calorimetry (DSC). Thermal-oxidative decomposition of the samples (i.e., pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by DSC. After encapsulation in liposomes, antioxidant activity proved to be higher than those of the same extracts in pure form.

In vitro studies on liposomal amphotericin B obtained by supercritical carbon dioxide-mediated process.

Nanotechnology in drug delivery is a rapidly expanding field. Nanosized liposomal preparations are already in use for efficient drug delivery with better therapeutic indices. Existing methods of liposome preparation are limited by problems of scale-up, difficulty in controlling size, and intercalation efficiency. Here we prepare amphotericin B-intercalated liposomes by a novel process where amphotericin B and purified phosphatidyl choline are solubilized in suitable solvent and precipitated in supercritical fluid carbon dioxide (known as a gas antisolvent technique), to obtain microsized particles that are subsequently introduced into a buffer solution. The morphology of liposomes was characterized through a phase-contrast microscope, and the particle size distribution studied by laser technique showed nanosize with a narrow range of size distribution (between 0.5 and 15 microm) and a higher intercalation efficiency. In vitro studies conducted using Aspergillus fumigatus (MTCC 870) strain proved to be efficient in the retardation of the growth of the organism.