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Vanadium in Technical Applications and Pharmaceutical Issues
Published in Jörg Rinklebe, Vanadium in Soils and Plants, 2023
However, the vanadate-phosphate antagonism is also a key answer to the insulin-mimetic effect of vanadate: vanadium coordination compounds such as the classical maltolato complex (1 in Figure 12.3), when hydrolytically and oxidatively converted to vanadate H2VO4− at physiological conditions, can enter cells via phosphate channels. Once in the intracellular environment, vanadate blocks off (deactivates) protein-tyrosine-phosphatase (PTP) via coordination to a PTP cysteinate residue (Irving and Stoker 2017; Hon et al. 2017). PTP is an enzyme that catalyzes the dephosphorylation of the intracellular tyrosine attached to the membrane-bound insulin receptor, a process that deactivates the insulin receptor. Blocking PTP prevents dephosphorylation and thus reactivates insulin uptake via the insulin receptor, consequently restoring intracellular glucose degradation: VIVO(maltol)2→→H2VO4−(extracellular)→H2VO4−(intracellular)→→PTP-CH2S(VO4H2)→insulin uptake by the insulin receptor Alternatively, peroxidovanadate H2VO3(O2)− can inactivate PTP by oxidation of the SH group in the cysteinyl residue (Huyer et al. 1997).
Chemical, physical, and biological properties of Pd(II), V(IV)O, and Ag(I) complexes of N3 tridentate pyridine-based Schiff base ligand
Published in Journal of Coordination Chemistry, 2020
L. H. Abdel-Rahman, A. M. Abu-Dief, F. M. Atlam, A. A. H. Abdel-Mawgoud, A. A. Alothman, A. M. Alsalme, A. Nafady
Cancer has been considered as one of the leading causes of human mortality worldwide, with more than ten million people dying annually. Many investigations using Schiff-base (imine) ligands coordinated with transition metal ions showed that such complexes possess anticancer activity [11–13]. In particular, Pd(II) chelates are used in various applications related to medicine and biology, given their proven antimicrobial, anti-inflammatory, and antitumor properties [14]. Silver sulfadiazine (SSD) has been utilized prophylactically for various bacterial infections. Vanadium acts as a counter ion for proteins (DNA and RNA). Moreover, oxidovanadyl Schiff base chelates are of interest as inhibitors of protein-tyrosine phosphatase 1B and DNA interacting reagents [15]. Although a massive body of work is reported on coordination chemistry and biological activity of Schiff bases with a variety of metal ions [14–18], little information is known about tridentate N3-imine ligands and their metal complexes.
Bio-medical potential of chalcone derivatives and their metal complexes as antidiabetic agents: a review
Published in Journal of Coordination Chemistry, 2021
Tyrosine phosphatases are named after their phosphate group removing function from phosphorylated tyrosine residues. Originally, phosphorylation of proteins which is a post-translational alteration is executed by kinases (enzymes) to synchronize the cell life [37]. Similarly, tyrosine kinase aids the insulin receptors present on the membrane to metabolize carbohydrates and fat from the bloodstream [38]. So, insulin receptor tyrosine kinase, which is present on the membrane, acts as the mediator to communicate the biological effects of insulin. Insulin receptor membrane has two subunits, ligand binding subunit and tyrosine kinase subunit. Initially, ligand binding subunit senses the insulin followed by activation of the tyrosine binding subunit prompting its autophosphorylation. This domino effect of two subunits initiates the phosphorylation of downstream insulin receptor substrate proteins. This pathway propagates the insulin signal leading to intake of glucose from the bloodstream to the cell [39] which is shown in Figure 1. But, tyrosine phosphatase plays the role of negative regulator and perturbs this pathway by removing the phosphate groups from crucial tyrosine residues instigating the resistance of receptors to insulin [39]. In addition to this, thiol group present on the cysteine residue’s active site of the protein tyrosine phosphatase (PTP1B) attacks as a nucleophile on enzyme employing the covalent catalysis and supervening in the formation of thiophosphoryl enzyme intermediate. So, the PTP1B activity can be completely aborted by substituting the cysteine residue [40]. Based on research, it is clinically approved that inhibition of PTP1B can serve as the target for therapeutic intercessions in type 2 diabetes mellitus [41].
Metal- and nonmetal-catalyzed synthesis of five-membered S,N-heterocycles
Published in Journal of Sulfur Chemistry, 2018
Navjeet Kaur, Nirmala Kumari Jangid, Vivek Sharma
The spiro-thiazolidine-oxindoles were formed from reactions of different isatin-3-imines [185–188] and isatin-3-hydrazones [189,190] with mercaptoacetic acid. The spiro-thiazolidinone-oxindoles act as potential selective inhibitors of Mycobacterium protein tyrosine phosphatase B. Mulwad and Mir [191] synthesized antibacterial N-(coumarin-6-yl)-spiro[thiazolidine-2-oxindole] derivatives on reacting isatin-3-semicarbazones with mercaptoacetic acid (Scheme 70) [192,193].