Min Jeong Noh

Extraction of epicuticular wax and nonacosan-10-OL fromEphedra herb utilizing supercritical carbon dioxide

Experimental results concerning the processing feasibility of using supercritical CO2 were reported for the extraction of epicuticular wax fromEphedra herb. Subsequently the isolability of nonacosan-10-ol from the total extract of epicuticular wax was evaluated by TLC and gas chromatography. Also, Soxhlet extractions ofEphedra herb by n-hexane and chloroform were performed and these results were compared with those obtained by supercritical CO2 extraction. As a result, we could demonstrate that supercritical CO2 can be an economical alternative to the organic solvents in processing the medicinal plant.

Measurements and correlation of effect of cosolvents on the solubilities of complex molecules in supercritical carbon dioxide

A new transparent microscale circulation-type high pressure equilibrium cell with on-line sampling was devised. With this apparatus, experimental solubility of molecularly complex species such as steroids (cholesterol, stigmasterol and ergosterol) and fatty acids (palmitic acid and stearic acid) in supercritical carbon dioxide(sc-C02) were measured. Also, to find an appropriate substance for enhancing both the polarity and the solubility power of the SC-CO2 solvent, we arbitrarily selected three polar substances such as acetone, methanol and water and the effect of these cosolvents on the solubility of solutes in SC-CO2 are examined. The supercritical phase equilibrium data of solute-cosolvent-sc-CO2 systems were quantitatively correlated using a new equation of state based on the lattice fluid theory incorporated with the concept of multibody interaction. We found that the addition of tracer amount of acetone or methanol to SC-CO2 enhances the solubility of all solutes about thirty to sixty times when compared with the case of pure sc-CO2 However, for the case of cosolvent water, no further enhancement of the solubility of solutes was realized. Also, the versatile fittability of the equation of state proposed in this work was demonstrated with the newly measured ternary supercritical equilibrium data.

Effect of functional groups on the solubilities of coumarin derivatives in supercritical carbon dioxide

SummarySolubilities in supercritical CO2 of coumarin, four monosubstituted coumarin derivatives (4-hydroxycoumarin, 7-hydroxycoumarin, 7-methoxycoumarin, and 7-methylcoumarin) and four disubstituted derivatives, (6,7-dihydroxycoumarin, 7-hydroxycoumarin-4-acetic acid, 7-methoxycoumarin-4-acetic acid, and 7-hydroxy-4-methylcoumarin) were measured in the temperature range 35–50 °C and the pressure range 8.5–25 MPa. In general, the substituted coumarin derivatives were less soluble than simple coumarin. It was also found that substitution at the C-4 position of coumarin tended to reduce the solubility more than substitution at the C-7 position. These solubility data are essential for the systematic application of SFE and SFC of coumarin derivatives from plant sources.

Comparison of supercritical carbon dioxide extraction with solvent extraction of nonacosan‐10‐ol, α‐amyrin acetate, squalene and stigmasterol from medicinal plants

Supercritical carbon dioxide extraction was carried out in the temperature range 35 to 60°C and from 10 to 30 MPa in order to obtain phytochemical components from several medicinal plants. These were nonacosan-10-ol (1) from the aerial parts of Ephedra sinica, α-amyrin acetate (2) from the root bark of Morus alba, and squalene (3) and stigmasterol (4) from the entire plant of Spirodela polyrhiza. For comparison, Soxhlet extraction with n-hexane was also carried out for these constituents. In the case of supercritical carbon dioxide extraction of 1, 2 and 4, the extraction yields tended to increase with increased temperature when the pressure was above 20 MPa. However, extraction yields were maximal at 40°C or 50°C below 15 MPa. When the amounts of extracts obtained by supercritical extraction are compared with those by Soxhlet extraction using n-hexane, it is apparent that supercritical carbon dioxide extraction can be used as an alternative method in the case of squalene and nonacosan-10-ol.

Measurement and modeling solubility of bioactive coumarin and its derivatives in supercritical carbon dioxide

To design a supercritical fluid extraction process for the separation of bioactive substances from natural products, a quantitative knowledge of phase equilibria between target biosolutes and solvent is necessary. How-ever, mostly no such information is available in literature to date. Thus in the present study, illustratively the solubility of bioactive coumarin and its various derivatives (i.e., hydroxy-, methyl-, and methoxy-derivatives) in supercritical CO2 were measured at 308.15–328.15 K and 10–30 MPa. Also, the pure physical properties such as normal boiling point, critical constants, acentric factor, molar volume and standard vapor pressure for coumarin and its derivatives were estimated. By these estimated information, the measured solubilities were quantitatively correlated by an approximate lattice equation of state proposed recently by the present authors.

Oxidation characteristics of phthalic and adipic acids by supercritical water

Supercritical water oxidation (SCWO) was carried out in a flow-type reactor for modeling of waste-water containing phthalic or adipic acid. For each acid, the reaction order and rate constant, k, were determined over a wide range of experimental conditions : temperatures from 633.15 to 713.15 K, pressures from 18 to 29 MPa, excess amounts of hydrogen peroxide from zero to 800 percent, and the mean residence time in the reactor from 1.1 to 49.1 seconds. The concentration of both acids in model wastewater was set by 500 ppm. For phthalic acid, we found that the orders of decomposition reaction with respect to the reactant concentrations were 0.56 for phthalic acid, 0.31 for hydrogen peroxide, and 0.53 for water. For adipic acid, the orders of oxidation were 0.78 for adipic acid, 0.53 for hydrogen peroxide, and 0.74 for water. Then measured activation energy for phthalic acid was 33.08 kcal/mol and that for adipic acid was 19.51 kcal/mol, respectively.

SUPERCRITICAL FLUID EXTRACTION AND BIOASSAY IDENTIFICATION OF PRODRUG SUBSTANCES FROM NATURAL RESOURCES

For arbitrarily chosen thirty types of natural resources which have been widely used in oriental traditional herb medicine, supercritical CO2 extraction (SFE) and organic liquid solvent extraction (LSE) withn-hexane, chloroform and methanol were carried out to extract pharmaceutical substances. To evaluate relative advantages and shortcomings between the SFE and LSE, five types of bioactivity assays as well as gas- and thin layer-chromatographic analysis were performed for all the extracts obtained by the two extraction methods. Types of bioassays performed included cytotoxicity, bleb forming, DNA binding, oxygen free radical scavenger and Xanthine oxidase inhibitor tests. To evaluate economic viability of the SFE over the traditional LSE, extractability of prodrug substances was evaluated as the functions of extraction temperature and pressure. SFE was proven to be a feasible alternative over LSE. Also, the optimum SFE conditions which provided maximum extraction and cytotoxicity for each selected sample were presented.

Searching prodrug substances from natural resources by supercritical carbon dioxide extraction and bioassay tests

Publisher Summary This chapter reviews a study conducted for searching pro-drug substances from natural resources by supercritical carbondioxide extraction and bioassay tests. In this study, supercritical fluid extraction (SFE) was combined with five types of bioassay tests to explore some bioactive substances from thirty types of natural resources available in Korean peninsula. Employed bioassays include cytotoxicity, bleb forming, DNA binding, oxygen-free radical scavenger, and xanthine oxidase inhibitor tests. To evaluate comparatively the economic viability of the SFE, organic liquid–solvent extraction (LSE) with n-hexane, chloroform, and methanol was also performed. To characterize the extracts, gas chromatography (GC) and high performance liquid chromatography (HPLC) are employed. To obtain the high-pure compounds from the candidate total extracts, column chromatographic separation is performed for some illustrative total extracts. For all the samples, the optimum SFE condition for each sample that gives maximum yield and cytotoxicity are discussed in the chapter. For many sample resources, the SFE is found to be advantageous over the LSE.