Heebyung Chai
Ohio State University
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Featured researches published by Heebyung Chai.
Pharmaceutical Research | 1994
Hayat Alkan-Onyuksel; Suganthi Ramakrishnan; Heebyung Chai; John M. Pezzuto
Taxol is a promising antitumor agent with poor water solubility. Intravenous administration of a current taxol formulation in a non-aqueous vehicle containing Cremophor EL may cause allergic reactions and precipitation upon aqueous dilution. In this study a novel approach to formulate taxol in aqueous medium for i.v. delivery is described. The drug is solubilized in bile salt (BS)/phospholipid (PC) mixed micelles. The solubilization potential of the mixed micelles increased as the total lipid concentration and the molar ratio of PC/BS increased. Precipitation of the drug upon dilution was avoided by the spontaneous formation of drug-loaded liposomes from mixed micelles. The formulation can be stored in a freeze-dried form as mixed micelles to achieve optimum stability, and liposomes can be prepared by simple dilution just before administration. As judged by a panel of cultured cell lines, the cytotoxic activity of taxol was retained when formulated as a mixed-micellar solution. Further, for the same solubilization potential, the mixed-micellar vehicle appeared to be less toxic than the standard nonaqueous vehicle of taxol containing Cremorphor EL.
Journal of Natural Products | 2011
A. Douglas Kinghorn; Li Pan; Joshua N. Fletcher; Heebyung Chai
Along with compounds from terrestrial microorganisms, the constituents of higher plants have provided a substantial number of the natural product-derived drugs used currently in Western medicine. Interest in the elucidation of new structures of the secondary metabolite constituents of plants has remained high among the natural products community over the first decade of the 21st century, particularly of species that are used in systems of traditional medicine or are utilized as botanical dietary supplements. In this review, progress made in the senior authors laboratory in research work on naturally occurring sweeteners and other taste-modifying substances and on potential anticancer agents from tropical plants will be described.
Bioorganic & Medicinal Chemistry Letters | 1999
Hyeh-Jean Jeong; Heebyung Chai; So-Young Park; Darrick S. H. L. Kim
Betulinic acid has been coupled with a series of amino acids at C-28 carboxylic acid position and the toxicity of the derivatives has been evaluated against cultured human melanoma (MEL-2) and human epidermoid carcinoma of the mouth (KB) cell lines. A number of amino acid conjugates of betulinic acid showed improved water solubility as well as selective cytotoxicity. This investigation demonstrates that amino acid conjugates of betulinic acid can produce potentially important derivatives, which may be developed as antitumor agents.
Tetrahedron | 1997
Baoliang Cui; Heebyung Chai; Thawatchai Santisuk; Vichai Reutrakul; Norman R. Farnsworth; Geoffrey A. Cordell; John M. Pezzuto; A. Douglas Kinghorn
Abstract Bioassay-guided fractionation of the stems and fruits of Aglaia elliptica using human oral epidermoid carcinoma (KB) cells, led to the isolation of five cyclopenta[b]benzofurans, constituted by methyl rocaglate (1) and four novel compounds (2–5), along with three known dammarane triterpenoids. Compound 5 possesses an unusual formyl ester substituent at the C-1 position. The structures of the novel compounds were established on the basis of spectroscopic methods. Compounds 1–5 were found to be very potent cytotoxic substances when evaluated against a panel of human cancer cell lines.
Journal of Natural Products | 2009
Han Ar; J. A. Kim; Daniel D. Lantvit; Kardono Lb; Riswan S; Heebyung Chai; Carcache de Blanco Ej; Norman R. Farnsworth; Swanson Sm; Kinghorn Ad
Bioassay-guided fractionation of a chloroform-soluble extract of Garcinia mangostana stem bark, using the HT-29 human colon cancer cell line and an enzyme-based ELISA NF-kappaB assay, led to the isolation of a new xanthone, 11-hydroxy-3-O-methyl-1-isomangostin (1). The structure of 1 was elucidated by spectroscopic data analysis. In addition, 10 other known compounds, 11-hydroxy-1-isomangostin (2), 11alpha-mangostanin (3), 3-isomangostin (4), alpha-mangostin (5), beta-mangostin (6), garcinone D (7), 9-hydroxycalabaxanthone (8), 8-deoxygartanin (9), gartanin (10), and cratoxyxanthone (11), were isolated. Compounds 4-8 exhibited cytotoxicity against the HT-29 cell line with ED50 values of 4.9, 1.7, 1.7, 2.3, and 9.1 microM, respectively. In an ELISA NF-kappaB assay, compounds 5-7, 9, and 10 inhibited p65 activation with IC50 values of 15.9, 12.1, 3.2, 11.3, and 19.0 microM, respectively, and 6 showed p50 inhibitory activity with an IC50 value of 7.5 microM. Alpha-mangostin (5) was further tested in an in vivo hollow fiber assay, using HT-29, LNCaP, and MCF-7 cells, but it was found to be inactive at the highest dose tested (20 mg/kg).
Phytochemistry | 1999
Gülaçtı Topçu; Ramazan Erenler; Osman Çakmak; Candan Johansson; Cennet Çelik; Heebyung Chai; John M. Pezzuto
From the hexane extract of berries of Juniperus excelsa, one new and four known diterpenes were isolated besides a known sesquiterpene. The structures of the known diterpenes were identified as isopimaric, isocommunic, (-)ent-trans communic and sandracopimaric acids, along with the sesquiterpene 4a-hydroxycedrol and the new compound which was elucidated as 3 alpha-acetoxylabda-8(17),13(16),14-trien-19-oic acid (juniperexcelsic acid). Cytotoxic activity of the hexane extract was investigated against a panel of cell line and found highly active against LNCaP, KB-V (+VLB) and KB-V (-VLB) cell lines. Furthermore, the hexane and methanol extracts, and the new compound were found to be moderately active against Mycobacterium tuberculosis.
Phytotherapy Research | 2008
Hideyuki Tomosaka; Young-Won Chin; Angela A. Salim; William J. Keller; Heebyung Chai; A. Douglas Kinghorn
Activity‐guided fractionation of an EtOAc‐soluble partition of the MeOH extract from the root bark of Berberis vulgaris L. (barberry), using a hydroxyl radical‐scavenging assay, led to the isolation and identification of three phenolic compounds of a previously known structure, N‐(p‐trans‐coumaroyl)tyramine, cannabisin G and (±)‐lyoniresinol. Of these, cannabisin G and (±)‐lyoniresinol exhibited antioxidant activity in this bioassay. Furthermore, it was found that cannabisin G showed cytoprotective activity in cultured MCF‐7 cells modulated by hydrogen peroxide. Copyright
Journal of Natural Products | 2001
Gloria L. Silva; Baoliang Cui; Daniel Chávez; Min You; Heebyung Chai; Philippe Rasoanaivo; Sean M. Lynn; Melanie J. O'neill; Jane Lewis; Jeffrey M. Besterman; Anne Monks; Norman R. Farnsworth; Geoffrey A. Cordell; John M. Pezzuto; A. Douglas Kinghorn
Nine tropane alkaloid aromatic esters (1-9) were isolated from the roots of Erythroxylum pervillei by following their potential to reverse multidrug-resistance with vinblastine-resistant oral epidermoid carcinoma (KB-V1) cells. All isolates, including seven new structures (3-9), were evaluated against a panel of human cancer cell lines, and it was found that alkaloids 3 and 5-9 showed the greatest activity with KB-V1 cells assessed in the presence of vinblastine, suggesting that these new compounds are potent modulators of P-glycoprotein. Confirmatory results were obtained with human ovarian adenocarcinoma (SKVLB) cells evaluated in the presence of adriamycin and synergistic studies performed with several cell lines from the NCI tumor panel. The structures of the new compounds were determined using spectroscopic techniques. Single-crystal X-ray analysis was performed on the monoester, tropane-3 alpha,6 beta,7 beta-triol 3-phenylacetate (1).
Phytochemistry | 1995
Long-Ze Lin; Shu-Fang Hu; Heebyung Chai; Thitima Pengsuparp; John M. Pezzuto; Geoffrey A. Cordell; Nijsiri Ruangrungsi
From Hymenocallis littoralis, one new alkaloid, named littoraline, together with 13 known lycorine alkaloids and one lignan, were isolated. The structure and NMR assignments of this new alkaloid were determined by 1D and 2D NMR techniques. Littoraline showed inhibitory activity of HIV reverse transcriptase, and lycorine and haemanthamine showed potent in vitro cytotoxicity.
Chemico-Biological Interactions | 1996
k-Soo Lee; Lisa A. Shamon; Heebyung Chai; Tangai E. Chagwedera; Jeffrey M. Besterman; Norman R. Farnsworth; Geoffrey A. Cordell; John M. Pezzuto; A. Douglas Kinghorn
Two structurally novel cytotoxic ent-kaurene diterpenoids, 13-methoxy-15-oxozoapatlin and 13-hydroxy-15-oxozoapatlin, were isolated from the root bark of Parinari curatellifolia, together with the known compound, 15-oxozoapatlin, on the basis of bioactivity-guided chromatographic fractionation and found to demonstrate broad-spectrum cytotoxic activity against a panel of cultured human cancer cell lines. The structures of these compounds were determined by analysis of their spectroscopic data. The presence of an alpha, beta-unsaturated carbonyl group in 13-methoxy-15-oxozoapatlin suggested that the cytotoxic potential of this compound could be mediated through reaction with cellular nucleophiles by means of a Michael-type addition. The compound 13-methoxy-15-oxozoapatlin reacted with the nucleophiles L-cysteine and beta-mercaptoethanol. The adduct with beta-mercaptoethanol was isolated, structurally characterized and found to be approximately 5-fold less cytotoxic than 13-methoxy-15-oxozoapatlin itself. The compound 13-methoxy-15-oxozoapatlin did not interact with DNA nor guanosine, and it was not mutagenic for Salmonella typhimurium strain TM677. The effects of 13-methoxy-15-oxozoapatlin on the growth of human cancer cells were analyzed utilizing cultured ZR-75-1 breast cancer cells. Biosynthesis of DNA, RNA and protein was reduced in treated cells, and accumulation at the G2/M phase of the cell cycle was observed. The compound 13-methoxy-15-oxozoapatlin did not mediate antimitotic activity with dibutyryl cAMP-treated cultured astrocytoma cells, suggesting that the cell cycle effect is G2 specific. No antitumor activity was observed when athymic mice carrying KB cells were treated with 13-methoxy-15-oxozoapatlin. These data indicate that the cytotoxic activity of 13-methoxy-15-oxozoapatlin is mediated in part by covalent reaction with a cellular component (such as sulfhydryl-containing protein) by means of a Michael-type addition, and this results in the blockage of cell-cycle progression.