Publications by authors named "DongHo Hong"

This paper presents the first fully automated reconstruction technique of 3D virtual colon segments from individual colonoscopy images. It is the basis of new software applications that may offer great benefits for improving quality of care for colonoscopy patients. For example, a 3D map of the areas inspected and uninspected during colonoscopy can be shown on request of the endoscopist during the procedure.

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Six compounds (1-6) were isolated from the methanol extract of Crinum latifolium by bioassay-guided separation. Among the six isolates, compounds 2 and 6 were new metabolites. Their structures were established as 4-senecioyloxymethyl-3,4-dimethoxycoumarin (2) and 5,6,3'-trihydroxy-7,8,4'-trimethoxyflavone (6) based on spectroscopic analyses.

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A series of 2, 5-dihydroxychalcones and related compounds were synthesized, and their cytotoxicities against tumor cell lines and human umbilical venous endothelial cells (HUVEC) evaluated. It was found that chalcones, with electron-withdrawing substituents on an A ring, exhibited significant cytotoxicities. Among the synthesized compounds, 2'-chloro-2, 5-dihydroxychalcone (9) was most potent, with an IC50 value as low as 0.

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A series of 2',5'-dihydroxychalcones were synthesized and evaluated for cytotoxicity against tumor cell lines and human umbilical venous endothelial cells (HUVEC). It was found that chalcones with electron-withdrawing substituents on the B ring exhibited potent cytotoxicity against a variety of tumor cell lines while compounds with electron-releasing groups were less potent in general. Those compounds with B ring replaced by extended or heteroaromatic rings exhibited significant bioactivity.

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Fourteen prodrugs of the antitumor agent 3-[(3-amino-4-methoxy)phenyl]-2-(3,4,5-trimethoxyphenyl)cyclopent-2-ene-1-one (1) were prepared to improve its water solubility and potency. These prodrugs include alpha-amino acid (1a-1h), aliphatic amino acid (1i-1l), phosphoramidate (1m), and phosphate (1n) derivatives. All of the prodrugs showed improved water solubility.

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A water fraction (EW), the remaining water phase from the methanol extract of Ephedra sinica after extraction with ethyl acetate and butanol, has been investigated for its antiangiogenic, antiinvasive and antitumour activities. It was observed that EW, at 30 micro g/mL, a non-cytotoxic concentration, inhibited the tube formation induced by human umbilical venous endothelial cells and the invasion of B16F10 melanoma cells through a matrix membrane by more than 90%. At 30 mg/kg/day, the inhibitory activity of EW on the growth of a tumour mass in BDF1 mice inoculated with B16-F10 murine melanoma cells was comparable to that of adriamycin (ADR) administered at 2 mg/kg/day.

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Two series of 2,3-diarylcyclopent-2-ene-1-ones including 2-aryl-3-(2,5-dihydroxyphenyl)cyclopent-2-ene-1-ones (2a-2f) and 3-aryl-2-3',4',5'-trimethoxyphenyl)cyclopent-2-ene-1-one (3a-3j) were synthesized and evaluated for the cytotoxicity against three tumor cell lines; B16F10, HCT116 and A431. It was found that the 3,4,5-trimethoxy substituent was optimal for the bioactivity of compounds in series 2. Meanwhile, compounds in series 3 exhibited the most potent cytotoxicity with 3-aryl ring being 4-methoxyphenyl (compound 3f), (3-hydroxy-4-methoxy)phenyl (compound 3e), or (3-amino-4-methoxy)phenyl (compound 3j).

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Eight rigid compounds designed as esterase-stable analogues of methyl 2,5-dihydroxycinnamate (1) were synthesized. These derivatives include 2-(2',5'-dihydroxybenzylidene)cyclopentenone (3a), 2-(2',5'-dihydroxybenzylidene)cyclohexanone (3b), 2,6-bis(2',5'-dihydroxybenzylidene)cyclohexanone (4b), 2,6-bis(2',5'-dihydroxybenzylidene)cyclopentenone (4a), (E)-3-(2',5'-dihydroxybenzylidene)pyrrolidin-2-one (5), (E)-5-(2',5'-dihydroxybenzylidene)-1,2-isothiazolidine-1,1-dioxide (6), 4-(2',5'-dihydroxyphenyl)-5H-furan-2-one (7), and 3-(2',5'-dihydroxyphenyl)cyclopent-2-ene-1-one (8). Among the eight compounds, the furanone 7 and cyclopentenone 8 showed the most potent cytotoxicity with IC50 values of 0.

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Through a systematic modification of the novel angiogenesis inhibitor 4-senecioyloxymethyl-6,7-dimethoxycoumarin (1) we found that a 6,7-dimethoxy moiety is important for bioactivity of 1. Replacement of the lactone functionality in coumarin 1 by an amide decreased its activity. By substitution of the senecioyl chain with various cinnamoyl groups we discovered 6d, bearing a 4-methoxycinnamoyl instead of senecioyl side chain, with inhibitory activity in HUVEC tube formation assay enhanced by one order of magnitude compared to 1.

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A series of 2-(3,4,5-trimethoxyphenyl)-3-arylcyclopent-2-ene-1-ones (8a-8e) and their related analogues, including pentenone 9a, pentenol 10a, pentene 12a, and furane 15, were synthesized and evaluated for cytotoxicity against murine and human tumor cell lines. Compounds 8a-c, 8e and 9a showed strong cytotoxicity with IC(50) values in the range of 8-34ng/mL. Compound 8e exhibited significant anti-tumor activity in BDF1 mice bearing Lewis lung carcinoma cells with an inhibition ratio of 59%.

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