• Journal of Environmental Science International
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• v.18 no.7
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• pp.797-802
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• 2009

To control degradation rate of biodegradable poly(lactide)s (PLA), the stereochemical PLAs with different ratios of d-lactide and l-lactide units were synthesized by the ring open polymerization and the their degradation kinetics were measured by a Langmuir film balance. The alkaline (pH=11) degradation of poly(l-lactide) (l-PLA) monolayer showed the faster rate at a surface pressure of 4 mN/m in the ranges from to 0 to 7 mN/m. However, the enzymatic degradation of l-PLA with Proteinase K did not occur until 4 mN/m. Above a constant surface pressure of 4 mN/m, the degradation rate was increased with a constant surface pressure. These behaviors might be attributed to the difference in the contacted area with degradation medium: alkaline ions need small contact area with l-PLA while enzymes require much bigger one to be activated due to different medium sizes. The stereochmical PLA monolayers showed that the alkaline degradation was increased with their optical impurities while the enzymatic one was inversed. These results could be explained by the decrease of crystallinity with the optical impurity and the inactivity of enzyme to d-LA unit.

• Journal of Pharmaceutical Investigation
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• v.35 no.1
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• pp.57-63
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• 2005

Numerous drugs are chiral because they possess one or more chiral centers. Enantiomers may differ in their pharmacokinetic, pharmacological and toxicological properties. However, the significance of stereochemistry of drugs in their therapeutic uses has received relatively little attention until recently. The US FDA issued a guideline on stereoisomeric drugs in 1992, and the European agency describes tests for new drug substances which are optically active in an ICH(International Conference of Harmonization) guideline. According to the guidance, enantiomers may differ in their pharmacokinetic, pharmacological and toxicological properties. Therefore, in this paper, we examined the recently published Canadian guidance, stereochemical issues in chiral drug development, which will be references to make a guidance on stereochemical issues in chiral drug development in Korea.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3623-3631
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• 2010

We prepared several novel molecular transporters built on myo- and scyllo-inositol scaffolds with variations in the number of guanidine residues, linker chain lengths and patterns. Some of these transporters were found to localize in mitochondria, and the mitochondrial affinity seems to be substantially related to the scaffold stereochemistry.

• Journal of the Korean Chemical Society
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• v.52 no.5
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• pp.503-510
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• 2008

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1645-1650
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• 2007

This paper describes a racemic and stereoselective synthetic route for a novel cyclohexenyl carbocyclic adenine analogue. The required stereochemistry of the target compound was controlled using a stereoselective glycolate Claisen rearrangement followed by α-chelated carbonyl addition. The introduction of 6-chloropurine was achieved using Mitsunobu conditions, and further modifications of the corresponding heterocycle gave the target cyclohexenyl nucleoside.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.304-306
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• 2004

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.2
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• pp.82-88
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• 2014

Three bicyclic and one monocyclic sesquiterpenoids were isolated from the marine sponge Topsentia species. Their planar structures were completely determined from a combination of extensive 1D and 2D NMR experiments, and also the relative stereochemistry on the chiral centers were established by the ROESY experiment. Compound 1 was determined as a new stereoisomer. Furthermore, the NMR spectral data for compounds 2 and 4, of which have not been reported, were listed. Four compounds did not show any cytotoxicity, instead compound 4 exhibited moderate antifungal activity against Candida albicans.

• Journal of Applied Biological Chemistry
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• v.48 no.2
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• pp.97-100
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• 2005

Chiral dienophile 5 was synthesized from D-glucose by consecutive diisopropylidenation, partial deprotection, diol cleavage, and Wittig reactions. Under thermal conditions, asymmetric Diels-Alder reaction between chiral dienophile and cyclopentadiene gave four possible chiral norbornenes stereoisomers whose absolute configurations were determined through CADD and NMR.

• Journal of the Korean Magnetic Resonance Society
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• v.7 no.1
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• pp.55-61
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• 2003

Sarcotragins C(1) and D(2), two novel compounds, have been isolated from the sponge Sarcotragus sp. collected from Jaeju Island, Korea. The structures of these compounds have been determined to be linear sesterterpene alkaloids on the basis of combined 1D and 2D NMR experiments. The stereochemistry involved was established by comparison of the NMR data with those reported for a similar compound.

• Journal of Photoscience
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• v.12 no.3
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• pp.185-186
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• 2005

The electronic structure of photoskinsensitizing psoralens has been investigated by the ab initio calculations. The photocycloaddition reaction of 8-methoxypsoralen with thymine is studied as a model for the photosensitizing reaction of psoralen with DNA bases. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of Syn, H-H, Syn, H-T formed through [2+2] addition reaction between the 3,4-double bonds of 8-methoxypsoralen and 5,6-double bond of thymine base.