Young Hae Choi

Bradykinin-12-lipoxygenase-VR1 signaling pathway for inflammatory hyperalgesia

The capsaicin-sensitive vanilloid receptor (VR1) was recently shown to play an important role in inflammatory pain (hyperalgesia), but the underlying mechanism is unknown. We hypothesized that pain-producing inflammatory mediators activate capsaicin receptors by inducing the production of fatty acid agonists of VR1. This study demonstrates that bradykinin, acting at B2 bradykinin receptors, excites sensory nerve endings by activating capsaicin receptors via production of 12-lipoxygenase metabolites of arachidonic acid. This finding identifies a mechanism that might be targeted in the development of new therapeutic strategies for the treatment of inflammatory pain.

Supercritical fluid extraction and liquid chromatographic-electrospray mass spectrometric analysis of stevioside fromStevia rebaudiana leaves

SummaryOptimal conditions were developed for the HPLC-ESI-MS and supercritical fluid extraction of stevioside fromStevia rebaudiana leaves. In the HPLC-ESI-MS of this compound, the negative ion mode showed higher sensitivity than both UV and the positive ion mode. In developing an alternative extraction method for stevioside using SFE, the effect of temperature, pressure, and percentage of modifier was evaluated on the extraction yield. Although sufficient extractability was not obtained by pure CO2 under any conditions of temperature and pressure, the addition of a modifier dramatically improved the extraction yield of stevioside, making it comparable to organic solvent extraction. Among the modifiers evaluated, the mixture of methanol and water showed greater extraction efficiency than the others. The extraction yield by CO2-methanol-water (80:16:4) was found to be 150% of conventional organic extraction. In addition to improving the extraction yield, SFE obviously provided a higher purity of stevioside in the final extract.

Strategies for supercritical fluid extraction of hyoscyamine and scopolamine salts using basified modifiers.

The supercritical fluid extraction behaviors of hyoscyamine and scopolamine were investigated and found to be highly dependent upon the chemical nature of the compounds. Free bases of hyoscyamine and scopolamine were freely soluble in supercritical CO2 with increasing temperature and pressure; however, the salts of these alkaloids were not soluble under any experimental conditions. It was found that alkaline modifiers such as methanol basified with diethylamine could enhance the solubilities and extraction yields of these alkaloids from plant matrices as compared to other modifiers.

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.

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 30u2009MPa 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 20u2009MPa. However, extraction yields were maximal at 40°C or 50°C below 15u2009MPa. 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.

Modifier effects on supercritical CO2 extraction efficiency of cephalotaxine fromCephalotaxus wilsoniana leaves

The effects of modifiers such as methanol, water, diethylamine in methanol (10 v/v %), and diethylamine in water (10 v/v %) were investigated at three different concentrations (1, 5, and 10 v/v %) of the modifiers in supercritical CO2 (SC-CO2) in order to enhance the supercritical fluid extraction (SFE) efficiency of cephalotaxine fromCephalotaxus wilsoniana leaves. Among the modifiers employed, methanol basified with diethylamine was found to greatly enhance the extraction efficiency relative to any other modifiers employed. The results suggest that cephalotaxine in plant matrices may be readily changed from SC-CO2-insoluble salt to SC-CO2-soluble free base by basified modifiers. In addition, SC-CO2 modified with basified methanol could enhance the extraction efficiency of cephalotaxine more than 30% when compared to the conventional organic solvent extraction.

A steroidal glycoside from Lepisorus ussuriensis

Abstract A new steroidal glycoside, 2α,3β-(22 R )-trihydroxycholestan-6-one-22- O -β- d -glucopyranosyl-(1→2)-α- l -arabinopyranoside, was isolated from the whole plants of Lepisorus ussuriensis , together with α-ecdysone and ecdysterone. Their structures were determined by means of spectroscopic and chemical methods.

A new triterpene lactone from the roots ofPatrinia scabiosaefolia

A new triterpene lactone named patrinolide A (1) has been isolated from the roots ofPatrinia scabiosaefolia (Valerianaceae). Its structure was determined to be 11β,21β-dihydroxy-3-oxooleanan-28,13β-olide on the basis of spectral analysis, including 2D-NMR techniques.

A flavonoid diglycoside from Lepisorus ussuriensis.

Abstract A new flavonoid, quercetin 3-methyl ether 7-O-α- l -arabinofuranosyl (1→6)-β- d -glucopyranoside , was isolated from the whole plant of Lepisorus ussuriensis , together with four known flavonoids.