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Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine. INORGANICS 2022. [DOI: 10.3390/inorganics10010008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Copper(II) complexes of glycyl-L-leucyl-L-histidine (GLH), sarcosyl-L-leucyl-L-histidine (Sar-LH), glycyl-L-phenylalanyl-L-histidine (GFH) and sarcosyl-L-phenylalanyl-L-histidine (Sar-FH) have potential anti-inflammatory activity, which can help to alleviate the symptoms associated with rheumatoid arthritis (RA). From pH 2–11, the MLH, ML, MLH-1 and MLH-2 species formed. The combination of species for each ligand was different, except at the physiological pH, where CuLH-2 predominated for all ligands. The prevalence of this species was supported by EPR, ultraviolet-visible spectrophotometry, and mass spectrometry, which suggested a square planar CuN4 coordination. All ligands have the same basicity for the amine and imidazole-N, but the methyl group of sarcosine decreased the stability of MLH and MLH-2 by 0.1–0.34 and 0.46–0.48 log units, respectively. Phenylalanine increased the stability of MLH and MLH-2 by 0.05–0.29 and 1.19–1.21 log units, respectively. For all ligands, 1H NMR identified two coordination modes for MLH, where copper(II) coordinates via the amine-N and neighboring carbonyl-O, as well as via the imidazole-N and carboxyl-O. EPR spectroscopy identified the MLH, ML and MLH-2 species for Cu-Sar-LH and suggested a CuN2O2 chromophore for ML. DFT calculations with water as a solvent confirmed the proposed coordination modes of each species at the B3LYP level combined with 6-31++G**.
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Savir S, Liew JWK, Vythilingam I, Lim YAL, Tan CH, Sim KS, Lee VS, Maah MJ, Tan KW. Nickel(II) Complexes with Polyhydroxybenzaldehyde and O,N,S tridentate Thiosemicarbazone ligands: Synthesis, Cytotoxicity, Antimalarial Activity, and Molecular Docking Studies. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130815] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Hammouda AN, Elmagbari FM, Jackson GE, Vicatos GM, Bonomo RP, Valora G. Stability, Structure, and Permeability Studies of Copper Tripeptide Species in Aqueous Solution. Aust J Chem 2021. [DOI: 10.1071/ch21040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The use of copper complexes to alleviate inflammation associated with rheumatoid arthritis (RA) is well known. This study focuses on designing a new drug that could be used to increase the bioavailability of copper and hence be more effective. The ligand chosen was sarcosyl-l-lysyl-l-lysine (Sar-Lys-Lys). The thermodynamic stability of H+, CuII, NiII, and ZnII complexes of Sar-Lys-Lys was measured in an aqueous solution at 298±0.01°C and an ionic strength of 0.15M (NaCl) using glass electrode potentiometry. UV-Vis, ESR, and 1H NMR spectroscopy was used to investigate the solution structures of the different species. At physiological pH, the ligand was found to coordinate via two amide nitrogens, the terminal amine, and the terminal carboxy group. The ε-amino group of lysine did not coordinate with the metal ion. Dermal absorption is the preferred method of administration and so this study used partition coefficients and tissue permeability studies to assess the bioavailability of the different complexes. Sar-Lys-Lys was found to increase the copper lipophilicity by a factor of 10 and increased tissue permeability by 30%.
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Savir S, Wei ZJ, Liew JWK, Vythilingam I, Lim YAL, Saad HM, Sim KS, Tan KW. Synthesis, cytotoxicity and antimalarial activities of thiosemicarbazones and their nickel (II) complexes. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128090] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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