Browsing by Author "Lai, Barry"

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    Cytotoxicity, cellular localization and photophysical properties of Re(I) tricarbonyl complexes bound to cysteine and its derivatives
    (Springer Nature, 2020-06-24) Capper, Miles S.; Enriquez Garcia, Alejandra; Macia, Nicolas; Lai, Barry; Lin, Jian-Bin; Nomura, Masaharu; Alihosseinzadeh, Amir; Ponnurangam, Sathish; Heyne, Belinda; Shemanko, Carrie S.; Jalilehvand, Farideh
    The potential chemotherapeutic properties coupled to photochemical transitions make the family of fac-[Re(CO)3(N,N)X]0/+ (N,N = a bidentate diimine such as 2,2'-bipyridine (bpy); X = halide, H2O, pyridine derivatives, PR3, etc.) complexes of special interest. We have investigated reactions of the aqua complex fac-[Re(CO)3(bpy)(H2O)](CF3SO3) (1) with potential anticancer activity with the amino acid l-cysteine (H2Cys), and its derivative N-acetyl-l-cysteine (H2NAC), as well as the tripeptide glutathione (H3A), under physiological conditions (pH 7.4, 37 °C), to model the interaction of 1 with thiol-containing proteins and enzymes, and the impact of such coordination on its photophysical properties and cytotoxicity. We report the syntheses and characterization of fac-[Re(CO)3(bpy)(HCys)]·0.5H2O (2), Na(fac-[Re(CO)3(bpy)(NAC)]) (3), and Na(fac-[Re(CO)3(bpy)(HA)])·H2O (4) using extended X-ray absorption spectroscopy, IR and NMR spectroscopy, electrospray ionization spectrometry, as well as the crystal structure of {fac-[Re(CO)3(bpy)(HCys)]}4·9H2O (2 + 1.75 H2O). The emission spectrum of 1 displays a variance in Stokes shift upon coordination of l-cysteine and N-acetyl-l-cysteine. Laser excitation at λ = 355 nm of methanol solutions of 1–3 was followed by measuring their ability to produce singlet oxygen (1O2) using direct detection methods. The cytotoxicity of 1 and its cysteine-bound complex 2 was assessed using the MDA-MB-231 breast cancer cell line, showing that the replacement of the aqua ligand on 1 with l-cysteine significantly reduced the cytotoxicity of the Re(I) tricarbonyl complex. Probing the cellular localization of 1 and 2 using X-ray fluorescence microscopy revealed an accumulation of 1 in the nuclear and/or perinuclear region, whereas the accumulation of 2 was considerably reduced, potentially explaining its reduced cytotoxicity.
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    Nuclear localization of dirhodium(II) complexes in breast cancer cells by X-ray fluorescence microscopy
    (The Royal Society of Chemistry, 2019-06-05) Enriquez Garcia, Alejandra; Lai, Barry; Gopinathan, Sesha Gopal; Harris, Hugh H.; Shemanko, Carrie S.; Jalilehvand, Farideh
    The cellular distribution of three dirhodium(II) complexes with a paddlewheel structure was investigated using synchrotron-based X-ray fluorescence microscopy and cell viability studies. Complexes with vacant axial sites displayed cytotoxic activity and nuclear accumulation whereas complexes in which the axial positions were blocked showed little to no toxicity nor uptake.
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    The effect of sodium thiosulfate on cytotoxicity of a diimine Re(I) tricarbonyl complex
    (The Royal Society of Chemistry, 2021-04-16) Capper, Miles S.; Enriquez Garcia, Alejandra; Lai, Barry; Wang, Baiwen O.; Gelfand, Benjamin S.; Shemanko, Carrie S.; Jalilehvand, Farideh
    Recently, diimine Re(I) tricarbonyl complexes have attracted great interest due to their promising cytotoxic effects. Here, we compare the cytotoxicity and cellular uptake of two Re(I) compounds fac-[(Re(CO)3(bpy)(H2O)](CF3SO3) (1) and Na(fac-[(Re(CO)3(bpy)(S2O3)])·H2O (bpy = 2,2?-bipyridine) (2). The Re-thiosulfate complex in 2 was characterized in two solvated crystal structures {Na(fac-[Re(CO)3(bpy)(S2O3)])·1.75H2O·C2H5OH}4 (2 + 0.75H2O + C2H5OH)4 and (fac-[Re(CO)3(bpy)(H2O)]) (fac-[Re(CO)3(bpy)(S2O3)])·4H2O (3). The cytotoxicity of 1 and 2 was tested in the MDA-MB-231 breast cancer cell line and compared with that of cisplatin. The cellular localization of the Re(I) complexes was investigated using synchrotron-based X-ray fluorescence microscopy (XFM). The results show that replacement of the aqua ligand with thiosulfate renders the complex less toxic most likely by distrupting its cellular entry. Therefore, thiosulfate could potentially have a similar chemoprotective effect against diimine fac-Re(CO)3 complexes as it has against cisplatin.