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Journal of Inorganic Biochemistry
Elsevier Science Publishing Co.
Journal of Inorganic Biochemistry

Elsevier Science Publishing Co.

0162-0134

Journal of Inorganic Biochemistry/Journal Journal of Inorganic BiochemistrySCIISTPAHCI
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    A combined experimental and computational study to discover novel tyrosinase inhibitors

    Amaral L.M.P.F.Moniz T.Leite A.Oliveira A....
    5页
    查看更多>>摘要:? 2022Depigmenting properties of tyrosinase inhibitors (TAi) boosted the search for new compounds applicable in cosmetics. Kojic acid, a 3-hydroxy-4-pyrone, is the most studied tyrosinase inhibitor but undesirable side effects, like dermatitis, and unspecified mechanism led to its exclusion in several countries. To discover safer and more efficient TA, we evaluated tyrosinase inhibitory effect of twelve 3-hydroxy-4-pyridinones (3,4-HPO) in vitro and considering the two reaction steps of inhibition in mushroom tyrosinase enzyme. In parallel we performed molecular docking studies in human and mushroom enzymes. Ligands I6 and I11 were the most effective compounds considering their inhibitory activity in both reaction steps. Our studies revealed that I6 has a non-competitive and mixed type of inhibition for monophenolase and diphenolase activity, while ligand I11 showed a mixed and competitive inhibition type for each reaction step. Molecular Docking results indicated that ligands tend to bind the enzyme by coordinating directly with the binuclear cooper centre and highlighted the relevance of voluminous and non-polar substituents at R2 to avoid the binding of the ligands to the enzyme. The work clarifies the type of inhibition established for kojic acid and points out the differences found for the set of 3,4-HPO chelators studied as prospective tyrosinase inhibitors.

    Insights into the transformation of VO2+ motif to VO3+, V2O34+ and VO2+ motifs and their interconversion along with a detailed mechanistic study of their anti-cancer activity in SiHa cervical cancer cells

    Patra D.Ghosh T.Pal A.Nath S....
    5页
    查看更多>>摘要:? 2022 Elsevier Inc.The basic criteria for the formation of complexes with VO3+, V2O34+ and VO2+ motifs from the VO2+ motif and their interconversion were explored utilizing two multidentate O,N-donor hydrazone ligands namely, E-2-Hydroxy-N′-(4-oxopentan-2-ylidine)benzohydrazide (H3L1) and E-2-Hydroxy-N′-(4-oxo-4-phenylbutan-2-ylidine)benzohydrazide (H3L2), derived from the condensation of 2-hydroxybenzoylhydrazide with acetylacetone and benzoylacetone respectively. Under aerobic condition, the possibility of forming complexes with different motifs in different solvents with varying pH was examined theoretically by computational methods with results that were verified experimentally. This study reveals that under aerobic condition, complexes with VO3+ (1,2) and V2O34+ (3, 4) motifs were formed in protic CH3OH and neutral CHCl3 solvent respectively while the formation of complexes (5–14) with VO2+ motif required protic CH3OH solvent and higher pH (≥ 7). Interconversion of VO3+, V2O34+ and VO2+ motifs are associated with specific acid-base equilibria, substantiated by 51V NMR titrations. Complexes containing these three motifs exhibited promising in vitro anticancer activity in SiHa cervical cancer cells without affecting healthy cells; among them complexes (5–14) with VO2+ motif are more potent. A detailed systematic mechanistic study was carried out, utilizing the two most potent complexes 5 and 6 (IC50 = 13, 6 μM respectively), which indicates that cytotoxicity and anti-proliferative activity of these complexes are manifested through oxidative stress induced apoptotic pathways (caspase mediated).

    Cytotoxicity and osteogenic effects of aluminum ions

    Kanamura N.Yamamoto T.Mizuno K.Boschetto F....
    5页
    查看更多>>摘要:? 2022 Elsevier Inc.In this study, we monitored the effect of Al3+ ions on mesenchymal cells (KUSA-A1) and human fibroblasts (NHDF) by means of in vitro experiments by culturing the cells with addition of small concentrations of aluminum ions (i.e., 0.1, 1, 10, and 100 ppm). Bone formation test was then conducted using KUSA-A1. Small concentrations of aluminum ions delayed but did not completely inhibit cell proliferation. The amount of bone tissue decreased as the concentration of Al3+ increased and crystallinity changes were also detected by Raman spectroscopic experiments. Moreover, Al3+ ions greatly affected both structure and chemistry of bone tissues with mineral nodules becoming larger and atomic substitution of Ca with Al in bone tissue being more preponderant with increasing Al3+ concentration. Such effects in turn impaired the balance between mineral and collagen in the formed bone tissue.

    Modulating aryl substitution: Does it play a role in the anti-leishmanial activity of a series of tetra-aryl Sb(V) fluorinated carboxylates?

    Artem'eva E.V.Efremov A.N.Sharutina O.K.Sharutin V.V....
    5页
    查看更多>>摘要:? 2022 Elsevier Inc.Eight tetra-arylantimony carboxylates of the general formula Ar4SbOC(O)R with Ar = Ph (a), p-Tol (b), R = C6F5 (1), CH2CF3 (2), CF2Br (3), CF2CF2CF3 (4) have been synthesised and characterised. Two of them (2b, 3b) are structurally novel. All structures were analytically characterised by FT-IR, 1H, 13C NMR spectroscopy. Previously synthesised structures were also analysed by X-ray diffraction and their solid-state structures authenticated. The solid-state structures exhibited a typical trigonal-bipyramidal geometry at the antimony centre, with the carboxylic oxygen and one of the aryl group carbons occupying axial positions with the remaining three aryl groups in the equatorial plane. All complexes were screened for their anti-leishmanial activity and cytotoxicity towards mammalian macrophages. No anti-leishmanial testing on tetra-arylantimony carboxylates have been previously performed. It was observed that the tetra-phenylantimony analogues are far more effective in comparison to the tetra-(p-tolyl)antimony complexes, with IC50 values in the ranges of 2.90–7.75 μM and 64.97–124.71 μM, respectively, for the promastigote assay, and 70.87–76.28 μM, 9.08–10.18 μM for the macrophages. Interestingly, the dose-response curve for tetra-phenylantimony carboxylates is a standard sigmoid curve, while for all tetra-(p-tolyl)antimony complexes it has an unusual inverted U-shape, indicating they are effective only at a low dose. All tetra-phenylantimony carboxylates were assessed for their anti-amastigote activity and showed promising results: 1.00% ± 1.44 (1a), 5,25% ± 1.72 (2a), 20.75% ± 8.46 (3a), 5.75% ± 1.62 (4a) at 10 μM.

    M?ssbauer studies of the ferryl, ferrous and ferric states of dehaloperoxidase from A. ornata

    Miller D.McGuire A.Dumarieh R.D'Antonio J....
    5页
    查看更多>>摘要:? 2021Dehaloperoxidase (DHP) is a multi-functional catalytic globin from the marine worm A. ornata, whose physiological functions include oxygen transport and oxidation of toxic substrates present in its habitat. In the Fe(III) state, DHPA has an isomer shift of 0.42 mm/s, characteristic for high-spin heme proteins. Changes in pH have subtle effects on the electronic structure of DHP in the Fe(III) state detectable in the high-field spectra, which show a pH-dependent mixture of species with different zero-field splittings between 5 and 18 cm?1. The short-lived intermediate obtained by direct reaction of the Fe(III) enzyme with H2O2 has an isomer shift of 0.10 mm/s, indicative of an Fe(IV)-oxo state and of an S = 1 electronic ground state confirmed by variable field studies. The O2-bound state of DHP has an isomer shift of 0.28 mm/s and a high-field spectrum characteristic for diamagnetic heme complexes, similarly to other haemoglobins. Overall, the isomer shift and quadrupole splitting of DHP in the four states studied are expectedly similar to both peroxidases and to myoglobin. The differences in electronic structure between DHP and other heme proteins and enzyme are observed in the high-field M?ssbauer spectra of the ferric state, which show pH-dependent zero-field splittings suggesting a heme site in which the ligand field strength at the iron ion is tuned by pH. This tunability is correlated with variable electron-donating properties of the iron, which can perform multiple functions.

    Substitution of the sole tryptophan of the cupredoxin, amicyanin, with 5-hydroxytryptophan alters fluorescence properties and energy transfer to the type 1 copper site

    Pastore A.J.Davidson V.L.Ficaretta E.Chatterjee A....
    5页
    查看更多>>摘要:? 2022 Elsevier Inc.Amicyanin is a type 1 copper protein with a single tryptophan residue. Using genetic code expansion, the tryptophan was selectively replaced with the unnatural amino acid, 5-hydroxytryptophan (5-HTP). The 5-HTP substituted amicyanin exhibited absorbance at 300–320 nm, characteristic of 5-HTP and not seen in native amicyanin. The fluorescence emission maximum in 5-HTP substituted amicyanin is redshifted from 318 nm in native amicyanin to 331 nm and to 348 nm in the unfolded protein. The fluorescence quantum yield of 5-HTP substituted amicyanin mutant was much less than that of native amicyanin. Differences in intrinsic fluorescence are explained by differences in the excited states of tryptophan versus 5-HTP and the intraprotein environment. The substitution of tryptophan with 5-HTP did not affect the visible absorbance and redox potential of the copper, which is 10 ? away. In amicyanin and other cupredoxins, an unexplained quenching of the intrinsic fluorescence by the bound copper is observed. However, the fluorescence of 5-HTP substituted amicyanin is not quenched by the copper. It is shown that the mechanism of quenching in native amicyanin is F?rster, or fluorescence, resonance energy transfer (FRET). This does not occur in 5-HTP substituted amicyanin because the fluorescence quantum yield is significantly lower and the red-shift of fluorescence emission maximum decreases overlap with the near UV absorbance of copper. Characterization of the distinct fluorescence properties of 5-HTP relative to tryptophan in amicyanin provides a basis for spectroscopic interrogation of the protein microenvironment using 5-HTP, and long-distance interactions with transition metals.

    Investigating the antiproliferative activities of new CuII complexes with pyridine hydrazone derivatives of nalidixic acid

    Ruiz A.L.T.G.de Carvalho J.E.Lustri W.R.de Paiva R.E.F....
    5页
    查看更多>>摘要:? 2022To further explore the structural features and potential antibacterial and antitumor activities of polynuclear CuII coordination compounds with nalidixic acid (nx) derivatives, new complexes bearing nx hydrazones with N-pyridinyl moieties substituted at positions 2 and 3 (h2py and h3py) were synthesized. Complexes [Cu3(C18H16N5O2)2(C18H17N5O2)2(H2O)]4BF4?H2O (1), and [Cu3(C18H16N5O2)2(C18H17N5O2)2(H2O)3]4BF4?3H2O (%) (2) were synthesized using h2py and h3py with Cu(BF4)2?nH2O as precursor, whereas the [Cu(C18H17N5O2)Cl2]?0.5H2O complex (3) was synthesized with h2py and CuCl2?2H2O. Crystallographic studies of complex 1, showed that coordination of hydrazones to CuII occurs by tridentate modes of type κ3(O,N,N′) as well as bidentate modes of type κ2(O′,N″). Complexes 1, 2 and 3 had their antiproliferative activities evaluated in vitro against a panel of tumor cells by the determination of GI50 values. Complexes 1 and 2 were more active than complex 3, suggesting an effect of the complex charge on their activities. The interactions of such complexes towards bovine serum albumin (BSA) and DNA plasmid (pGEX-4 T1) were investigated using fluorescence spectroscopy and gel electrophoresis. All complexes were shown to interact with the DNA model as metallonucleases, but no interaction with BSA was observed. DNA molecular docking of complex 1 encompassing both its trinuclear (TN) form and a possible mononuclear (MN) derivative suggests that naphthyridyl ring performs π-stacking interactions with DNA. The TN species were also shown to be possible minor groove binders.

    Interaction of pharmacologically active pyrone and pyridinone vanadium(IV,V) complexes with cytochrome c

    Ugone V.Pisanu F.Garribba E.
    5页
    查看更多>>摘要:? 2022 Elsevier Inc.The interaction between cytochrome c (Cyt) and potential vanadium drugs, formed by 1,2-dimethyl-3-hydroxy-4(1H)-pyridinonate (dhp) and maltolate (ma), was studied by ElectroSpray Ionization-Mass Spectrometry (ESI-MS). Since under physiological conditions redox processes are possible, the binding of the complexes in the oxidation state +IV and +V, [VIVO(dhp)2], [VIVO(ma)2], [VVO2(dhp)2]? and [VVO2(ma)2]?, was examined. In all systems VIV,V–L–Cyt adducts are observed, their formation depending on V oxidation state, ligand L and metal concentration. The larger stability of vanadium(IV) than vanadium(V) complexes favors the interaction of the moieties VIVOL2 and VIVOL+ with VIV, while with VV adducts with VVO2L and VVO2+ fragments are observed. The analysis of the protein structure suggests that Glu4, Glu21, Asp50, Glu62, Glu66 and Glu104 are the most plausible candidates for monodentate coordination, while the couples (Asp2, Glu4), (Glu92, Asp93) and (His33, Glu104) for bidentate binding. The values of E1/2 for [VIVO(dhp)2] and [VIVO(ma)2], measured by cyclic voltammetry (CV), 0.53 V and 0.60 V vs. standard hydrogen electrode, indicate that the oxidation of VIV to VV is possible. The presence of a protein can alter the redox behavior and stabilize one of the states, VIV or VV. Overall, the data reinforce the conclusion that, for V drugs, the biotransformation is fundamental to explain their biological action and the analysis should not be limited to the ligand exchange and hydrolysis but also include the redox processes, and that a mixture of VIV and VV species, VIV,V–L–Protein and VIV,V–Protein, could be responsible of the pharmacological effects.

    Cytotoxic and antiparasitic activities of diphosphine-metal complexes of group 10 containing acylthiourea as ligands

    de Oliveira T.D.Ribeiro G.H.Honorato J.Leite C.M....
    5页
    查看更多>>摘要:? 2022In this work, group 10 transition metal complexes bearing dppe [1,2-bis(diphenylphosphino)ethane] and acylthiourea ligands were evaluated for their cytotoxic and antiparasitic activities. Six new complexes with a general formula [M(Ln)(dppe)]BF4 [where M = NiII, PdII or PtII; Ln = N, N′-dimethyl-N-benzoyl thiourea (L1) or N, N′-dimethyl-N-tiofenyl thiourea (L2) were synthesized and characterized by infrared, NMR (31P{1H}, 1H and 13C{1H}) spectroscopies, elemental analysis and molar conductivity. The structures of the complexes were confirmed by X-ray diffraction technique. The biological activity of the complexes was evaluated on breast cancer cells (MDA-MB-231 and MCF-7) and causative agents of chagas disease and leishmaniasis. The complexes presented higher cytotoxicity for breast cancer cell lines compared to non-tumor cells. Nickel complexes stood out when evaluated against the triple-negative breast cancer line (MDA-MB-231), presenting considerably lower IC50 values (about 10 to 22×), when compared to palladium and platinum complexes, and the cisplatin drug. When evaluated on the triple-negative line (MDA-MB-231), the complexes [Ni(L2)(dppe)]BF4 (2), [Pd(L2)(dppe)]BF4 (4) and [Pt(L2)(dppe)]BF4 (6) were able to induce cell morphological changes, influence on the cell colony formation and the size of the cells. The complexes inhibit cell migration and cause changes to the cell cytoskeleton and nuclear arrangement. In the same cell line, the compounds caused cell arrest in the Sub-G1 phase of the cell cycle. The compounds were also tested against the Trypanosom Cruzi (T. cruzi) and Leishmania sp. parasites, which cause Chagas and leishmaniasis disease, respectively. The compounds showed good anti-parasitic activity, mainly for T. cruzi, with lower IC50 values, when compared to the commercial drug, benznidazole. The compounds interact with CT-DNA, indicating that interaction occurs by the minor groove of the biomolecule.

    Rhenium(I) derivatives of aminoquinoline and imidazolopiperidine-based ligands: Synthesis, in vitro and in silico biological evaluation against Plasmodium falciparum

    Sovari S.N.Zobi F.Golding T.M.Mbaba M....
    5页
    查看更多>>摘要:? 2022A small library of aminoquinoline and imidazolopiperidine (IMP)-based ligands, containing the 1,2,3-triazole moiety, and their corresponding tricarbonyl rhenium complexes were synthesised and their inhibitory activities evaluated against the chloroquine-sensitive (CQS) and multidrug-resistant (MDR) strains (NF54 and K1, respectively) of P. falciparum. The quinoline-based compounds (L1, L2, ReL1, and ReL2) were at least six-fold more potent than their IMP-based counterparts (L3, L4, ReL3, and ReL4) against both strains of P. falciparum, with the most promising compound (L1) displaying activity comparable to chloroquine diphosphate (CQDP) in the MDR strain. Additionally, all of the synthesised compounds have resistance indices less than CQDP. To gain insight into a possible mechanism of action, in silico hemozoin docking simulations were performed. These studies proposed that the tested compounds may act via hemozoin inhibition, as the new aminoquinoline-derivatives, with the exception of complex ReL2 (binding affinity: ?12.62 kcal/mol), showed higher binding affinities than the reference drug chloroquine (CQ, ?13.56 kcal/mol). Furthermore, the ligands exhibited superior binding affinity relative to their corresponding Re(I) complexes, which is reflected in their antiplasmodial activity.