title: Biological evaluation of bismuth non-steroidal anti-inflammatory drugs (BiNSAIDs): stability, toxicity and uptake in HCT-8 colon cancer cells.
abstract: Recent studies showed that the metal-coordinated non-steroidal anti-inflammatory drug (NSAID), copper indomethacin, reduced aberrant crypt formation in the rodent colon cancer model, while also exhibiting gastrointestinal sparing properties. In the present study, the stability and biological activity of three BiNSAIDs of the general formula [Bi(L)3]n, where L=diflunisal (difl), mefenamate (mef) or tolfenamate (tolf) were examined. NMR spectroscopy of high concentrations of BiNSAIDs (24h in cell medium, 37°C) indicated that their structural stability and interactions with cell medium components were NSAID specific. Assessment of cell viability using the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium]bromide (MTT) assay showed that the toxicity ranking of the BiNSAIDs paralleled those of the respective free NSAIDs: diflH<mefH<tolfH. While the IC50 values of the BiNSAIDs (ranging between 16 and 81μM) were lower than the free NSAIDs, it was apparent that the toxicity of the BiNSAIDs was due to the molar ratio of the three NSAID molecules contained in the BiNSAIDs, with the exception of [Bi(difl)3]. The highest cellular bismuth content was observed following treatment with [Bi(tolf)3]. Since NMR studies indicated that [Bi(tolf)3] was the most stable BiNSAID and that cellular uptake of bismuth correlated with structural stability it appears that bismuth uptake is assisted by the NSAID. Microprobe SR-XRF imaging showed that the intracellular fate of bismuth was independent of the specific BiNSAID treatment whereby all BiNSAID-treated cells showed bismuth accumulation in the cytoplasm within 24-h exposure. The size and location of the hot spots (0.3-5.8μm(2)), were consistent with cellular organelles such as lysosomes.
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Hawksworth
authors.affiliation: School of Chemistry, Monash University, Clayton, Victoria, 3168, Australia.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Andrews
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
authors.forename: Wilford
authors.initials: W
authors.lastname: Lie
authors.affiliation: X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Barry
authors.initials: B
authors.lastname: Lai
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, New South Wales, 2522, Australia. Electronic address: carolynd@uow.edu.au.
authors.forename: Carolyn T
authors.initials: CT
authors.lastname: Dillon
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D001729:Bismuth / Q000737:chemistry*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms; D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D004061:Diflunisal / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D006801:Humans; D020128:Inhibitory Concentration 50; D008528:Mefenamic Acid / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D062367:ortho-Aminobenzoates / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D056831:Coordination Complexes; D062367:ortho-Aminobenzoates; D008528:Mefenamic Acid; C009500:tolfenamic acid; D004061:Diflunisal; D001729:Bismuth
keywords: Bismuth; Colon cancer; Microprobe synchrotron radiation X-ray fluorescence imaging; Non-steroidal anti-inflammatory drug