Protective effect of zinc-N-acetylcysteine on the rat kidney during cold storage

Cold storage of kidneys before transplantation is problematic because of the limited survival time of the allografts. In this study, zinc-N-acetylcysteine (ZnNAC) was shown to be a potent endonuclease inhibitor and antioxidant, and it was tested as a potential additive to a cold storage solution for kidney preservation. Exposure of normal rat kidney NRK-52E cells to ZnNAC resulted in zinc delivery to the cells as determined by TFL-Zn fluorophore and partial protection of the cells against injury by cold storage in University of Wisconsin solution (UWS) as measured by propidium iodide assay. Ex vivo, rat kidneys demonstrated time- and temperature-dependent DNA fragmentation as assessed by TUNEL assay, indicating irreversible cell death. DNA fragmentation was faster in the medulla than in the cortex, and tubules were affected more than glomeruli. Perfusion of rat kidneys with cold ZnNAC solution in UWS significantly inhibited cell death both in the cortex and medulla at concentrations of 0.3-30 mM compared with UWS alone, with a maximum effect at 1-10 mM ZnNAC. Cold storage of the kidney significantly increased quantities of cleaved caspase-3 and endonuclease G (EndoG) in the tissue, which were abolished by 10 mM ZnNAC, indicating its ability to suppress both caspase-dependent and -independent cell death. Therefore, supplementation of UWS with ZnNAC can decrease DNA fragmentation and protect kidney allografts from cell death due to cold storage.

Thorough study of reactivity of various compound classes toward the Folin-Ciocalteu reagent

A thorough study was done to test the reactivity of the Folin-Ciocalteu (F-C) reagent toward various compound classes. Over 80 compounds were tested. Compound classes included phenols, thiols, vitamins, amino acids, proteins, nucleotide bases, unsaturated fatty acids, carbohydrates, organic acids, inorganic ions, metal complexes, aldehydes, and ketones. All phenols, proteins, and thiols tested were reactive toward the reagent. Many vitamin derivatives were also reactive, as were the inorganic ions Fe(+2), Mn(2+), I(-), and SO(3)(2-). Other compounds showing reactivity included the nucleotide base guanine and the trioses glyceraldehyde and dihydroxyacetone. Copper complexation enhanced the reactivity of salicylate derivatives toward the reagent, whereas zinc complexation did not. Several amino acids and sugars that were reported to be reactive toward the F-C reagent in earlier studies were found not to be reactive in this study, at least in the concentrations used. Reaction kinetics of each compound with the F-C reagent were also measured. Most compounds tested showed a biphasic kinetic pattern with half-lives under 1 min. Trolox and ascorbic acid displayed a rapid monophasic pattern in which the reaction reached end point within 1 min. In summary, this study has shown that the F-C reagent is significantly reactive toward other compounds besides phenols. As other investigators have suggested, the F-C assay should be seen as a measure of total antioxidant capacity rather than phenolic content. Because phenolics are the most abundant antioxidants in most plants, it gives a rough approximation of total phenolic content in most cases.

Co-treatment with copper compounds dramatically decreases toxicities observed with cisplatin cancer therapy and the anticancer efficacy of some copper chelates supports the conclusion that copper chelate therapy may be markedly more effective and less toxic than cisplatin therapy

Co-Administration of Cu(II) chelates are reported to decrease life threatening Cisplatin [Pt(II) (NH3)2(CL)2]-induced acute degenerative renal, gastrointestinal, thymic, and bone marrow states consistent with serious necrotizing and immune-mediated inflammatory disease. Initially it was found that copper sulfate treatment completely prevented lethality as well as gastric and nephrotoxicity without compromising Pt(II) (NH3)2(CL) 2 antineoplastic activity, which led to suggestions that prior Cu(II)-treatment be used clinically to prevent serious side effects of Pt(II) (NH3)2(CL)2-treatment. In the course of these studies it was discovered that Cu(II)-treatments alone inhibited neoplastic growth and increased survival of rat and mouse models of cancer. Subsequently it was discovered that a stable non-toxic and non-polar lipophilic chelate, Copper(II)2(3,5-diisopropylsalicylate)4, caused redifferentiation of cultured neuroblastoma and mouse muscle-implanted mammary adenocarcinoma without neoplastic cell killing. Another stable non-toxic and non-polar lipophilic chelate, Copper(II)2(3,5-ditertiarybutylsalicylate)4, was found to prevent Bax-initiated and caspases-3-activation mediated apoptosis. These remarkable observations are concluded to be due to enzyme-mimetic or modulating reactivities of Cu(II) chelates and/or facilitation of Cu(II or I)-dependent enzyme syntheses required to overcome inflammatory-neoplastic disease states. Further, approaches to treating neoplastic diseases by removal of Cu from tissues with ammonium tetrathiomolybdate in an anticopper approach to therapy are not well founded based upon existing scientific literature.

Prevention of cisplatin-induced kidney epithelial cell apoptosis with a Cu superoxide dismutase-mimetic [copper2II(3,5-ditertiarybutylsalicylate)4(ethanol)4]

Copper(2)(II)(3,5-ditertiarybutylsalicylate)(4)(ethanol)(4), Cu(2)(II)(3,5-DTBS)(4)(Eth)(4), was synthesized and characterized for evaluation as an anti-apoptotic superoxide dismutase (SOD)-mimetic in an in vitro 50 microM cis-diamminedichloroplatinum(II), [Pt(II)(NH(3))(2)(Cl)(2)]-treated kidney proximal tubule epithelial cell (LLC-PK) preparation. Synthesized Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) was characterized by elemental analysis, FTIR spectrophotometry, and X-ray crystallography. The IC(50) for SOD-mimetic reactivity of Cu(2)(II)(3,5-DTBS)(4)(Eth)(4), determined with the xanthine/xanthine oxidase/nitroblue tetrazolium (NBT) system, was found to be 2.69 microM for the binuclear chelate. Pretreatment of LLC-PK cells with 20 microM Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) prevented 50 microM Pt(II)(NH(3))(2)(Cl)(2)-induced and superoxide-mediated apoptosis. This SOD-mimetic significantly suppressed Pt(II)(NH(3))(2)(Cl)(2)-induced translocation of pro-apoptotic Bax from the cytosol to the inner mitochondrial membrane, prevented Pt(II)(NH(3))(2)(Cl)(2)-induced release of cytochrome c from the inner mitochondrial membrane and the appearance of cytochrome c in the cytosol, and prevented conversion of procaspase-3 to active caspase-3. Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) treatment inhibited Pt(II)(NH(3))(2)(Cl)(2)-mediated tubular cell injury by preventing activation of cellular mechanisms that lead to proximal tubule kidney cell death. Based on these observations, Pt(II)(NH(3))(2)(Cl)(2)- induced O(2)(-)-mediated apoptosis can be mechanistically overcome with a small molecular mass SOD-mimetic, Cu(2)(II)(3,5-DTBS)(4)(Eth)(4). Prior treatment of patients who are to undergo treatment with Pt(II)(NH(3))(2)(Cl)(2) for their neoplastic disease with Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) may be beneficial to these patients.