@article {1271,
	title = {Modulation of the G(2) cell cycle checkpoint by sesquiterpene lactones psilostachyins A and C isolated from the common ragweed Ambrosia artemisiifolia},
	journal = {Planta Medica},
	volume = {71},
	number = {10},
	year = {2005},
	note = {ISI Document Delivery No.: 985TLTimes Cited: 8Cited Reference Count: 30},
	month = {Oct},
	pages = {938-943},
	type = {Article},
	abstract = {A phenotypic cell-based assay for inhibitors of the G(2) DNA damage checkpoint was used to screen plant extracts from the US National Cancer Institute Natural Products Repository. It revealed activity in a methanol extract from the common ragweed Ambrosia artemisiifolia. Assay-guided fractionation led to the identification of the sesquiterpene lactones psilostachyins A and C as novel checkpoint inhibitors. Elimination of their alpha,beta-unsaturated carbonyl group caused a loss of activity, suggesting that the compounds can bind covalently to target proteins through Michael addition. Psilostachyins A and C also blocked cells in mitosis and caused the formation of aberrant microtubule spindles. However, the compounds did not interfere with microtubule polymerization in vitro. The related sesquiterpene lactones psilostachyin 13, paulitin and isopaulitin were also isolated from the same extract but showed no checkpoint inhibition. The identification of the target(s) of psilostachyins A and C may provide further insight into the signalling pathways involved in cell cycle arrest and mitotic progression.},
	keywords = {Ambrosia artemisiffolia, CAFFEINE, CANCER, cell cycle, checkpoint, CHK1, DILACTONE, DNA-DAMAGE CHECKPOINT, G(2) phase, INHIBITION, KINASE, MCF-7 CELLS, mitosis, P53, PROTEIN, UCN-01},
	isbn = {0032-0943},
	url = {<Go to ISI>://000233401400009},
	author = {Sturgeon, C. M. and Craig, K. and Brown, C. and Rundle, N. T. and Andersen, R. J. and Roberge, M.}
}
@article {5181,
	title = {G(2) DNA damage checkpoint inhibition and antimitotic activity of 13-hydroxy-15-oxozoapatlin},
	journal = {Journal of Biological Chemistry},
	volume = {276},
	number = {51},
	year = {2001},
	note = {ISI Document Delivery No.: 505QLTimes Cited: 24Cited Reference Count: 51},
	month = {Dec},
	pages = {48231-48236},
	type = {Article},
	abstract = {Checkpoints activated in response to DNA damage cause arrest in the G(1) and G(2) phases of the cell cycle. Inhibitors of the G(2) checkpoint may be used as tools to study this response and also to increase the effectiveness of DNA-damaging therapies against cancers lacking p53 function. Using a cell-based assay for G(2) check. point inhibitors, we have screened extracts from the NCI National Institutes of Health Natural Products Repository and have identified 13-hydroxy-15-oxozoapatlin (OZ) from the African tree Parinari curatellifolia. Flow cytometry with a mitosis-specific antibody showed that checkpoint inhibition by OZ was maximal at 10 muM, which released 20\% of irradiated MCF-7 cells expressing defective p53 and 30\% of irradiated HCT116p53(-/-) cells from G(2) arrest. OZ additively increased the response to the checkpoint inhibitors isogranulatimide and debromohymenialdisine, but it did not augment the effects of UCN-01 or caffeine. Unlike other checkpoint inhibitors, OZ did not inhibit ataxia-telangiectasia mutated (ATM), ATM and Rad3-related (ATR), Chk1, Chk2, Plk1, or Ser/Thr protein phosphatases in vitro. Treatment with OZ also caused G(2)-arrested and cycling cells to arrest in mitosis in a state resembling prometaphase. In these cells, the chromosomes were condensed and scattered over disordered mitotic spindles. The results demonstrate that OZ is both a G(2) checkpoint inhibitor and an antimitotic agent.},
	keywords = {ARREST, BHK CELLS, CAFFEINE, CELL-CYCLE CHECKPOINTS, CHROMOSOME ALIGNMENT, G2, P34(CDC2) KINASE, PROTEIN-KINASE, RADIOSENSITIZING AGENT, TYROSINE KINASE, UCN-01},
	isbn = {0021-9258},
	url = {<Go to ISI>://000172927000066},
	author = {Rundle, N. T. and Xu, L. and Andersen, R. J. and Roberge, M.}
}
