Won Hee Kim

Efficient and practical synthesis of l-hamamelose

An efficient synthetic route of L-hamamelose was successfully accomplished starting from D-ribose. L-Hamamelose was synthesized in 42% overall yield with six reaction steps via a stereoselective Grignard reaction, a stereoselective crossed aldol reaction and a controlled oxidative cleavage of the double bond of a vinyl diol compound. During the oxidative cleavage of the double bond of the vinyl diol compound with osmium tetroxide and NaIO(4), an over-oxidative cleavage of alpha-hydroxyl aldehyde generated from ring opening of the first cleaved product, formyl lactol, did not occur, probably due to the stability of the lactol form. A plausible mechanism for the stereoselective crossed aldol reaction was suggested. The final target compound, L-hamamelose can play a very important role as a chiral building block in synthesizing a wide variety of enantiopure compounds.

Synthesis of enantiomerically pure d- and l-bicyclo[3.1.0]hexenyl carbanucleosides and their antiviral evaluation

Abstract Based upon the fact that l-nucleosides have been generally known to be less cytotoxic than d-counterparts, l-bicyclo[3.1.0]hexenyl carbanucleoside derivatives with a fixed north conformation were designed and synthesized by employing a novel synthetic strategy starting from (R)-epichlorohydrin in order to search for new anti-HIV agents with high potency and less cytotoxicity. A tandem alkylation, γ-lactonization, a chemoselective reduction of ester in the presence of γ-lactone functional group, a RCM reaction, and a Mitsunobu coupling reaction were used as key reactions. d-Counterpart nucleosides were also prepared according to the same synthetic method. Among the synthesized carbanucleosides, d-thymine nucleoside, d-2 and l-thymine nucleoside, l-2 exhibited excellent anti-HIV-1 and -2 activities, in MT-4 cells, which were higher than those of ddI, an anti-AIDS drug. Whereas d-2 exhibited high cytotoxicity in MT-4 cell lines, l-2 did not show any discernible cytotoxicity in all cell lines tested, reflecting that l-2 may be a good candidate for an anti-AIDS drug. l-2 also showed weak anti-HSV-2 activity without cytotoxicity. However, none of the synthesized nucleosides exhibited antiviral activities against RNA viruses including coxsakie, influenza, corona and polio viruses, maybe due to their 2′,3′-dideoxy structure. Potent antiviral effects of d-2 and l-2 indicate that nucleosides belonging to a class of D4Ns can be an excellent candidate for anti-DNA virus agents. This research strongly supports l-nucleosides of a class of D4Ns to be a very promising candidate for antiviral agents due to its low cytotoxicity and a good antiviral activity.

A double blind, placebo-controlled, randomized clinical trial that breast milk derived Lactobacillus gasseri BNR17 mitigated diarrhea-dominant irritable bowel syndrome

The exact pathogenesis of diarrhea-dominant irritable bowel syndrome (IBS) is not known, but the abnormal microbiota of the gastrointestinal tract is considered to be one of the important contributing factors as in other gastrointestinal diseases such as inflammatory bowel disease, antibiotic-associated diarrhea, and colorectal cancer as well as systemic diseases. Though diverse trials of probiotics had been continued in the treatment of diarrhea-IBS, only a few proved by randomized clinical trial. To prove the efficacy of Lactobacillus gasseri BNR17 isolated from breast milk in patients with diarrhea-IBS, prospective, randomized, placebo controlled clinical trial was done including health related-quality of life analysis, colon transit time, and the changes of fecal microbiota. BNR17 significantly improved the symptoms of diarrhea compared to control group. Health related-QOL analysis showed significant improvement of abdominal pain, distension, disturbed daily life, and mean defecation frequency with BNR17. On comparative CTT before and after BNR17, 6 out of 24 subjects showed significant correction of rapid colon transit pattern, while only 2 out of 24 in placebo (p<0.01). Upon fecal microbiota analysis, BNR17 significantly increased B. fecalis, E. rectale, C. aerofaciens, F. prausnitzil and B. steroris. Conclusively, Lactobacillus gasseri BNR17 can be a potential probiotics to ameliorate diarrhea-IBS.

Phenotypic and molecular characteristics of second clone (T 0 V 2 ) plants of the LeLs-antisense gene-transgenic chrysanthemum line exhibiting non-branching

환경위해성평가 연구 대상인 형질전환 이벤트로서의 자격을 확인하고자 형질전환세대(

Synthesis of Pyrimidine Analog of Fluoroneplanocin A as Potential Anti- HCV Agent

T_0V_0

Effect of Kelpak ® on the promotion of in vitro rooting in transgenic rose plantlets

)에서와 같이 영양번식 제1세대(

New embryogenesis from atypical bodies and plant regeneration from long-term subcultured embryogenic callus in rose

T_0V_1

Synthesis of Novel Cyclopropyl Nucleoside Analogues as Potential Antiherpetic Agent

)에서도 도입유전자 LeLs-antisense의 발현 특성인 무측지성을 유지한 국화 무측지성 형질전환계통 LeLs80의 영양번식 제2세대(

Synthesis of Neplanocin A Analog with 2'-"up"-C-Methyl Substituent as Potential Anti-HCV Agent

T_0V_2

Anticancer effects of the MHY218 novel hydroxamic acid-derived histone deacetylase inhibitor in human ovarian cancer cells.

)의 형태적 및 분자 생물학적 특성을 조사하였다. LeLs80 계통의