• Journal of Microbiology and Biotechnology
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• v.1 no.1
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• pp.79-83
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• 1991

The effects of phosphate concentration in the medium, feeding of biosynthetic precursor, and the addition of exogenous berberine on cell growth and berberine production were studied in cell suspension cultures of Thalictrum rugosum. The depletion of phosphate in the medium enhanced the specific productivity up to twofold with significant release of berberine into the medium. Extracellular berberine was 19% of the total in the culture without phosphate while it was 2-5% of total berberine in the culture with even low amounts of phosphate. Precursor feeding was not effective in enhancing alkaloid formation. Initial presence of exogenous berberine did not have much effect on cell growth and alkaloid production. It was found that the cells have the capacity to take up large quantities of berberine. When $500{\;}mg{\cdot}l^{-1}$ of berberine was added exogenously at the beginning, 81% of total berberine was found in the cells.

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.999-1004
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• 2001

(1-Chloro-2,2-dicyanovinyl)benzene or 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene was reacted with 2-amino-phenol to give the model compound, hydroxy enaminonitrile, which was found to undergo thermal cyclization reaction to form the corresponding benzoxazole. This intramolecular cyclization reaction is expected to occur through nucleophilic attack to electropositive enamine carbon by ortho-hydroxy group on the phenyl ring, which is accompanied by the release of neutral malononitrile through rearrangement. From each bifunctional monomer, o-hydroxy substituted polyenaminonitrile was prepared and characterized as a new precursor polymer for well-known aromatic polybenzoxazole. Also the unusual macrocyclic dimer formation from the 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane polymerization reaction system was discussed. The thermal cyclization reactions and the properties of polymers were investigated using FT-IR and thermal analysis (DSC & TGA).

• Archives of Pharmacal Research
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• v.28 no.11
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• pp.1275-1281
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• 2005

The $G_{q/11}$ protein-coupled receptors, such as muscarinic (M1 & M3) receptors, have been shown to regulate the release of a soluble amyloid precursor protein (sAPP$\alpha$) produced from $\alpha$-secretase processing. However, there is no direct evidence for the precise characteristics of G proteins, and the signaling mechanism for the regulation of $G_{q/11}$ protein-coupled receptor mediated sAPP$\alpha$ release is not clearly understood. This study examined whether the muscarinic receptor-mediated release of sAPP$\alpha$ is directly regulated by $G\alpha_{q/11}$ proteins. The HEK293 cells were transiently cotransfected with muscarinic M3 receptors and a dominant-negative minigene construct of the G protein $\alpha$ subunit. The sAPP$\alpha$ release in the media was measured using an antibody specific for sAPP. The sAPP$\alpha$ release enhancement induced by muscarinic receptor stimulation was decreased by a $G_{q/11}$ minigene construct, whereas it was not blocked by a control minigene construct (the G$\alpha$ carboxy peptide in random order, G$\alpha_{q}$R) or $G\alpha_{j}$ constructs. This indicated a direct role of the $G\alpha_{q/11}$ protein in the regulation of muscarinic M3 receptor-mediated sAPP$\alpha$ release. We also investigated whether the transactivation of the epidermal growth factor receptor (EGFR) by a muscarinic agonist could regulate the sAPP$\alpha$ release in SH-SY5Y cells. Pretreatment of a specific EGFR kinase inhibitor, tyrophostin AG1478 (250 nM), blocked the EGF-stimulated sAPP$\alpha$ release, but did not block the oxoM­stimulated sAPP$\alpha$ release. This demonstrated that the transactivation of the EGFR by muscarinic receptor activation was not involved in the muscarinic receptor-mediated sAPP$\alpha$ release.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.372-376
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• 2006

Ferulic acid is a phenolic compound that serves as a major biosynthetic precursor of vanillin in higher plants. We investigated the ability of the 3 commercial enzymes - Ultraflo L, Viscozyme L, and ${\alpha}-Amylase$ - to induce the release ferulic acid from the Ipomoea batatas L. (sweet potato) stem. The rate of release for ferulic acid was optimal when Ultraflo L (1.0%) was used compared with the other enzymes, whereas Viscozyme L was most effective for the release of vanillic acid and vanillin. Thus, these enzymes may be useful for the large-scale production of ferulic acid and other phenolic compounds from sweet potato stem.

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.29-33
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• 1996

Mono-, or di-substituted chlorodicyanovinyl benzene compound was reacted with an excess amount of ethylenediamine to give corresponding imidazoline product with high reaction yield. This reaction occurs by stable imidazoline ring-forming process through nucleophilic attack of terminal amine on the enaminonitrile adduct, the reaction intermediate, toward electropositive enamine carbon, which is accompanied by the release of neutral malononitrile moiety. The similar reaction with 1,2-phenylenediamine produced stable enaminonitrile-amine adduct at lower temperature which could be cyclized intramolecularly to thermally stable benzimidazole at elevated temperature in solution or in solid state. From the difunctional compound of both reactants, poly(enaminonitrile-amine) could be prepared as a new soluble precursor polymer for well-known polybenzimidazole (PBI). The thermal cyclization reaction accompanying the release of malononitrile molecules was studied using thermalanalysis and infrared spectroscopy.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.37-40
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• 1998

Aromatic polybenzoxazoles have been known since 1964 as a class of aromatic heterocyclic polymers that exhibit excellent thermal stability. Polyhydroxyamides (PHA), precursor polymers to PBO, can cyclize to farm stable heterocyclic polymers with the simultaneous release of small molecules, which can be expected to act as a fire quencher. (omitted)

• Rapid Communication in Photoscience
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• v.5 no.2
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• pp.16-17
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• 2016

Arylalkyne cobalt complexes 5, 6 were prepared and irradiated with e-beam to study their fragmentation focused in alkyne formation. Thioaryl complex 6 showed facile CO ligand release and generated parent alkyne in 89% relative intensity. Meanwhile, hydroxyaryl complex 5 gave alkyne in 6% relative intensity.

• Environmental Mutagens and Carcinogens
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• v.25 no.1
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• pp.19-24
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• 2005

The Swedish double mutation (KM670/671NL) of amyloid precursor protein (Swe-APP) is associated with early-onset familial Alzheimer's disease (FAD) and increases amyloid beta peptide production. Although APP/A/3 mediated neurotoxicity is observed both in vitro and in vivo, the relationship between mutant APP expression, A/3 production, and neuronal death observed in the brains of FAD patients remains to be elucidated. In this study, we investigated the mechanisms of Swe-APP-induced cell death in HEK293 and NGF-differentiated PC 12 cells. We found that the expression of Swe-APP induced cytochrome C relase, activation of caspase 3 in HEK 293 and NGF-differentiated PC 12 cells. We also show that the reactive oxygen species (ROS) was detected in Swe-APP expressing HEK 293 cells and NGF-differentiated PC 12 cells and that pretreatment with vitamine E attenuated the cellular death, cytochrome C release induced by Swe-APP expression, indicating the involvement of free radical in these processes. These results suggest one of possible apoptotic mechanisms of Swe-APP which could occur through cytochrome C release from mitochondria and this apoptosis inducing effects could be at least in part, due to ROS generation by Swe-APP expression.

• Journal of Ginseng Research
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• v.43 no.2
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• pp.236-241
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• 2019

Background: Thromboxane A2 ($TXA_2$) induces platelet aggregation and promotes thrombus formation. Although ginsenoside Ro (G-Ro) from Panax ginseng is known to exhibit a $Ca^{2+}-antagonistic$ antiplatelet effect, whether it inhibits $Ca^{2+}-dependent$ cytosolic phospholipase $A_2$ ($cPLA_{2{\alpha}}$) activity to prevent the release of arachidonic acid (AA), a $TXA_2$ precursor, is unknown. In this study, we attempted to identify the mechanism underlying G-Ro-mediated $TXA_2$ inhibition. Methods: We investigated whether G-Ro attenuates $TXA_2$ production and its associated molecules, such as cyclooxygenase-1 (COX-1), $TXA_2$ synthase (TXAS), $cPLA_{2{\alpha}}$, mitogen-activated protein kinases, and AA. To assay COX-1 and TXAS, we used microsomal fraction of platelets. Results: G-Ro reduced $TXA_2$ production by inhibiting AA release. It acted by decreasing the phosphorylation of $cPLA_{2{\alpha}}$, p38-mitogen-activated protein kinase, and c-Jun N-terminal kinase1, rather than by inhibiting COX-1 and TXAS in thrombin-activated human platelets. Conclusion: G-Ro inhibits AA release to attenuate $TXA_2$ production, which may counteract $TXA_2-associated$ thrombosis.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.13-24
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• 2017

In this study, nanoparticles which encapsulated hydrophobic antimicrobial compounds with 50wt% of payload and 70%of solid content were prepared. These nanoparticles could be dispersed at water as well as various medium. Water dispersible organic-inorganic (O-I) hybrid nanoparticles were first prepared using alkoxysilane-functionalized amphiphilic polymer precursors through a conventional sol-gel process. Hydrophobic antimicrobial compound, Eugenol encapsulated nanoparticles were prepared using these O-I hybrid nanoparticles through a new nanoprecipitation process. The effect of various preparation on the size of nanoparticles, amount of payload, antimicrobial activity, and release rate of encapsulated compounds was investigated. All eugenol-encapsulated O-I nanoparticles regardless of preparation condition showed the same minimal inhibitory concentration (MIC) (50mg/ml) and 99% of antimicrobial activity for every strain. Their antimicrobial activity could maintain longer than two weeks. Especially, eugenol-encapsulated O-I nanoparticles prepared using tetraethoxysilane (TEOS) exhibited the highest payload (50wt%) and the lowest release rate which was owing to higher inorganic content in the O-I nanoparticles. And these O-I nanoparticles dispersed in hexanediol (HD) showed the highest antimicrobial activity and solid content (70wt%) because HD acted as a solvent as well as a antimicrobial agent.