TY - JOUR
T1 - Inhibitors of DNA polymerase β
T2 - Activity and mechanism
AU - Gao, Zhijie
AU - Maloney, David J.
AU - Dedkova, Larisa M.
AU - Hecht, Sidney M.
N1 - Funding Information:
Compounds MHz NMR spectrometer and a Varian Gemini 300 NMR spectrometer. All nm) or by dipping the plates in a vanillin staining reagent. Silicycle (Quebec City, Quebec) ultra pure silica gel, mesh size 35–75 μm, was used for column chromatography. 1 and 4 were purchased from Sigma Chemicals; compound 3 was from Aldrich. Compound 2 was synthesized as described below ( Scheme 1 ). Experiments requiring anhydrous conditions were performed using flame-dried glassware and under a nitrogen atmosphere. Chemical reagents were purchased from Aldrich Chemical Co. Anhydrous CH 2 Cl 2 was distilled from CaH 2 prior to use. 1 H and 13 C NMR spectra were recorded on a Varian Unity 500 δ values are given in ppm and are relative to tetramethylsilane; J values are recorded in Hz. High resolution mass spectral data were obtained at the Michigan State University Mass Spectrometry Facility, which is supported, in part, by a Grant (DRR-00180) from the Biotechnology Research Technology Program, National Center for Research Resources, National Institutes of Health. Thin layer chromatography was performed using Merck silica gel F 254 pre-coated plates with spots visualized using UV light (254
Funding Information:
This work was supported by NIH Research Grant CA50771, awarded by the National Cancer Institute.
PY - 2008/4/15
Y1 - 2008/4/15
N2 - Bioassay-guided fractionation of extracts prepared from Couepia polyandra and Edgeworthia gardneri resulted in the isolation of the DNA polymerase β (pol β) inhibitors oleanolic acid (1), edgeworin (2), betulinic acid (3), and stigmasterol (4). Study of these pol β inhibitors revealed that three of them inhibited both the lyase and polymerase activities of DNA polymerase β, while stigmasterol inhibited only the lyase activity. Further investigation indicated that the four inhibitors had substantially different effects on the DNA-pol β binary complex that is believed to be an obligatory intermediate in the lyase reaction. It was found that the inhibitors potentiated the inhibitory action of the anticancer drug bleomycin in cultured A549 cells, without any influence on the expression of pol β in the cells. The results of the unscheduled DNA synthesis assay support the thesis that the potentiation of bleomycin cytotoxicity by DNA pol β inhibitors was a result of an inhibition of DNA repair synthesis.
AB - Bioassay-guided fractionation of extracts prepared from Couepia polyandra and Edgeworthia gardneri resulted in the isolation of the DNA polymerase β (pol β) inhibitors oleanolic acid (1), edgeworin (2), betulinic acid (3), and stigmasterol (4). Study of these pol β inhibitors revealed that three of them inhibited both the lyase and polymerase activities of DNA polymerase β, while stigmasterol inhibited only the lyase activity. Further investigation indicated that the four inhibitors had substantially different effects on the DNA-pol β binary complex that is believed to be an obligatory intermediate in the lyase reaction. It was found that the inhibitors potentiated the inhibitory action of the anticancer drug bleomycin in cultured A549 cells, without any influence on the expression of pol β in the cells. The results of the unscheduled DNA synthesis assay support the thesis that the potentiation of bleomycin cytotoxicity by DNA pol β inhibitors was a result of an inhibition of DNA repair synthesis.
KW - Antitumor agent potentiation
KW - Enzyme-DNA covalent complex
KW - Inhibition mechanism
KW - Natural products
KW - Polymerase inhibitor
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U2 - 10.1016/j.bmc.2008.02.071
DO - 10.1016/j.bmc.2008.02.071
M3 - Article
C2 - 18343122
AN - SCOPUS:42149157403
SN - 0968-0896
VL - 16
SP - 4331
EP - 4340
JO - Bioorganic and Medicinal Chemistry
JF - Bioorganic and Medicinal Chemistry
IS - 8
ER -