Jung-Mi Hah

Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase.

Three nitric oxide synthase (NOS) isoforms, eNOS, nNOS and iNOS, generate nitric oxide (NO) crucial to the cardiovascular, nervous and host defense systems, respectively. Development of isoform-selective NOS inhibitors is of considerable therapeutic importance. Crystal structures of nNOS-selective dipeptide inhibitors in complex with both nNOS and eNOS were solved and the inhibitors were found to adopt a curled conformation in nNOS but an extended conformation in eNOS. We hypothesized that a single-residue difference in the active site, Asp597 (nNOS) versus Asn368 (eNOS), is responsible for the favored binding in nNOS. In the D597N nNOS mutant crystal structure, a bound inhibitor switches to the extended conformation and its inhibition of nNOS decreases >200-fold. Therefore, a single-residue difference is responsible for more than two orders of magnitude selectivity in inhibition of nNOS over eNOS by L-Nω-nitroarginine-containing dipeptide inhibitors.

Synthesis of pyrrolo[2,3-d]pyrimidine derivatives and their antiproliferative activity against melanoma cell line

Synthesis of a new series of diarylureas and amides having pyrrolo[2,3-d]pyrimidine scaffold is described. Their in vitro antiproliferative activities against A375 human melanoma cell line and HS 27 fibroblast cell line were tested and the effect of substituents on pyrrolo[2,3-d]pyrimidine was investigated. The newly synthesized compounds, except N-acetyl derivatives (Id, Ie, and Im), generally showed superior or similar activity against A375 to Sorafenib. Among all of these derivatives, compounds Iq and Ir having imidazole and morpholine moieties, respectively, showed the most potent antiproliferative activity against A375.

Correlation between Performance of QM/MM Docking and Simple Classification of Binding Sites

Use of SiteMap for binding site classification and its connection to QM/MM (quantum mechanics/ molecular mechanics) docking performance were investigated. Using the hydrophilic/hydrophobic character values along with balance between them which SiteMap calculates, we sorted 455 cocrystal complexes available from protein data bank into three groups and tested how Glide, a conventional docking program, and QPLD, a QM/MM docking program, perform on them. QPLD showed improvements on all three groups over Glide but with varying degrees. Analysis of the results was carried out, and establishment of correlations between the classification of binding sites and QM/MM docking performance was attempted. It was found that QM/MM docking delivers the most improvements for primarily hydrophobic binding sites with substantial hydrophilic interactions. Based on our findings, we make suggestions for use of QM/MM docking and directions for further developments.

Aminoquinoline derivatives with antiproliferative activity against melanoma cell line

The synthesis of a novel series of aminoquinoline derivatives 1a-p and their antiproliferative activities against A375 human melanoma cell line were described. Most compounds showed superior antiproliferative activities to Sorafenib as a reference compound. Among them, quinolinyloxymethylphenyl compounds 1k and 1l exhibited potent activities (IC(50)=0.77 and 0.79microM, respectively) and excellent selectivity against melanoma and fibroblast cell lines.

1,4-dihydropyrazolo[4,3-d]imidazole phenyl derivatives: a novel type II Raf kinase inhibitors.

The synthesis of a novel series of 1,4-dihydropyrazolo[4,3-d]imidazole phenyl derivatives 1a-b, 2a-v and their antiproliferative activities against A375P and WM3629 human melanoma cell line were described. Most compounds showed competitive antiproliferative activities to sorafenib, the reference standard. Among them, pyrazoloimidazole phenyl urea compounds 2a, 2d, 2g, 2i, 2t exhibited potent activities on WM3629 cell lines (IC(50)=0.56-0.86 microM). Especially, 2t was found to be a potent and selective C-Raf inhibitor, showing a possibility as melanoma therapeutics.

New diarylureas and diarylamides possessing acet(benz)amidophenyl scaffold: design, synthesis, and antiproliferative activity against melanoma cell line.

A series of new diarylurea and diarylamide derivatives possessing acet(benz)amidophenyl scaffold was synthesized. Their in vitro antiproliferative activity was tested against A375P human melanoma cell line. Compounds 1c,d and 2c,d showed the highest potencies with IC(50) values in sub-micromolar scale. In addition, compounds 1b,e,l and 2e,l were more potent than Sorafenib but with IC(50) values in micromolar range. Moreover, compound 2c was equipotent to Vemurafenib, and 2d showed higher potency than Vemurafenib against A375P. Molar refractometry calculation and ADME profiling of the highest potent four derivatives 1c,d and 2c,d are also reported.

Discovery and initial SAR of pyrimidin-4-yl-1H-imidazole derivatives with antiproliferative activity against melanoma cell lines.

The synthesis of a novel series of pyrimidin-4-yl-1H-imidazol-2-yl derivatives 7, 8, 9 and their antiproliferative activities against A375P human melanoma cell line and WM3629 cell line were described. Most compounds showed superior antiproliferative activities compared to Sorafenib, the well-known RAF inhibitor. Among them, 7a exhibited potent activities on both cell lines (IC(50)=0.62 and 4.49muM, respectively) and turned out to be a selective and potent CRAF inhibitor.

Structure based design and syntheses of amino-1H-pyrazole amide derivatives as selective Raf kinase inhibitors in melanoma cells

The synthesis of a novel series of N-(5-amino-1-(4-methoxybenzyl)-1H-pyrazol-4-yl amide derivatives 6a-o, 7a-s and their antiproliferative activities against A375P melanoma cell line were described. Most compounds showed competitive antiproliferative activities to sorafenib, the reference standard. Among them, N-(5-amino-1-(4-methoxybenzyl)-1H-pyrazol-4-yl)-5-(3-(4-chloro-3-(trifluoromethyl)phenyl) ureido)-2-methylbenzamide 7c exhibited potent activities (GI(50)=0.27 μM). Especially, 7c was found to be a potent and selective B-Raf V600E and C-Raf inhibitor (IC(50)=0.26 μM, IC(50)=0.11 μM, respectively), showing a possibility as melanoma therapeutics.

Enhanced solubility and bioavailability of flurbiprofen by cycloamylose

The effect of cycloamylose on the aqueous solubility of flurbiprofen was investigated. To improve the solubility and bioavailability of flurbiprofen (poor water solubility), a solid dispersion was spray dried with a solution of flurbiprofen and cycloamylose at a weight ratio of 1:1. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with a commercial product. Cycloamylose increased solubility of flurbiprofen approximately 12-fold and dissolution of it by 2-fold. Flurbiprofen was present in an unchanged crystalline state, and cycloamylose was a solubilizing agent for flurbiprofen in this solid dispersion. Furthermore, the dispersion gave higher AUC and Cmax values compared with the commercial product, indicating that it improved the oral bioavailability of flurbiprofen in rats. Thus, the solid dispersion may be useful to deliver flurbiprofen with enhanced bioavailability without changes in crystalline structure.

Synthesis of aminoquinazoline derivatives and their antiproliferative activities against melanoma cell line.

The synthesis of a novel series of aminoquinazoline derivatives 1a-r and their antiproliferative activities against A375 human melanoma cell line were described. Among them, six compounds showed superior antiproliferative activities to Sorafenib as a reference compound. In particular, the representative compound 1q bearing chromen-4-one moiety exhibited excellent antiproliferative activity (IC(50)=0.006 μM) and good selectivity over HS27 fibroblast cell line.