Diethylalkylsulfonamido(4-methoxyphenyl)methyl)phosphonate/phosphonic acid derivatives act as acid phosphatase inhibitors: synthesis accompanied by experimental and molecular modeling assessments

Optimization of an α-aminonaphthylmethylphosphonic acid inhibitor of purple acid phosphatase using rational structure-based design approaches

Purple acid phosphatases (PAPs) are ubiquitous binuclear metallohydrolases that have been isolated from various animals, plants and some types of fungi. In humans and mice, elevated PAP activity in osteoclasts is associated with osteoporosis, making human PAP an attractive target for the development of anti-osteoporotic drugs. Based on previous studies focusing on phosphonate scaffolds, as well as a new crystal structure of a PAP in complex with a derivative of a previously synthesized α-aminonaphthylmethylphosphonic acid, phosphonates 24-40 were designed as new PAP inhibitor candidates. Subsequent docking studies predicted that all of these compounds are likely to interact strongly with the active site of human PAP and most are likely to interact strongly with the active site of pig PAP. The seventeen candidates were synthesized with good yields and nine of them (26-28, 30, 33-36 and 38) inhibit in the sub-micromolar to nanomolar range against pig PAP, with 28 and 35 being the most potent mammalian PAP inhibitors reported with K_i values of 168 nM and 186 nM, respectively. This study thus paves the way for the next stage of drug development for phosphonate inhibitors of PAPs as anti-osteoporotic agents.

In vitroexperiments and infrared spectroscopy analysis of acid and alkaline phosphatase inhibition by vanadium complexes

Two oxidovanadium complexes with 4-aminobenzoic acid and/or the peroxo anion as ligands were synthesized and characterized by elemental analysis, conductivity measurements, TGA/DTA,¹H NMR, EPR, FTIR, and UV/vis spectroscopies.

Potential bio-protective effect of copper compounds: mimicking SOD and peroxidases enzymes and inhibiting acid phosphatase as a target for anti-osteoporotic chemotherapeutics

Copper complexes with transformed methimazole ligand have been synthesized and characterized by elemental analysis, conductivity measurements, thermogravimetric analysis, EPR, FTIR and UV-Vis spectroscopies. Results support their stoichiometries and geometrical structures: [Cu(C₄H₅N₂S)₂Cl₂]·2H₂O(1), [Cu(C₈H₁₀N₄S)SO₄H₂O](2) and [Cu(C₈H₁₀N₄S)SO₄](3). ((C₄H₅N₂)₂S: bis(l-methylimidazol-2-yl)sulfide; (C₄H₅N₂S)₂ = Bis[bis(l-methylimidazol-2-yl)disulfide]) Concurrently, the structurally distinct soluble species corresponding to complexes (1) and (2) were subsequently used in an in vitro investigation of their potential biological properties. In view of their possible pharmaceutical activity, the complexes were in vitro evaluated as phosphatase acid inhibitors. Their radical bio-protective effects were also studied measuring the effect against DPPH^• and O₂^•- radicals. Additional catalytic properties as peroxidase mimics were evaluated using Michaelis-Menten kinetic model by means of phenol red and pyrogallol assays. The complexes exhibited catalytic bromination activity and the ability to oxidize pyrogallol substrate indicating that they can be considered as functional models. The relationships between the structures and the in vitro biological activities have also been considered. Serum protein albumin has attracted the greatest interest as drug carrier and the affinity of biological/pharmaceutical compound is relevant to the development of new medicine. In that sense, interaction studies by fluorescence and EPR spectroscopies were performed showing the binding capacity of the complexes.

Synthesis, biological activity and molecular modelling studies of shikimic acid derivatives as inhibitors of the shikimate dehydrogenase enzyme of Escherichia coli

Shikimic acid (SA) pathway is the common route used by bacteria, plants, fungi, algae, and certain Apicomplexa parasites for the biosynthesis of aromatic amino acids and other secondary metabolites. As this essential pathway is absent in mammals designing inhibitors against implied enzymes may lead to the development of antimicrobial and herbicidal agents harmless to humans. Shikimate dehydrogenase (SDH) is the fourth enzyme of the SA pathway. In this contribution, a series of SA amide derivatives were synthesised and evaluated for in vitro SDH inhibition and antibacterial activity against Escherichia coli. All tested compounds showed to be mixed type inhibitors; diamide derivatives displayed more inhibitory activity than synthesised monoamides. Among the evaluated compounds, molecules called 4a and 4b were the most active derivatives with IC50 588 and 589 µM, respectively. Molecular modelling studies suggested two different binding modes of monoamide and diamide derivatives to the SDH enzyme of E. coli.

A Potent Tartrate Resistant Acid Phosphatase Inhibitor to Study the Function of TRAP in Alveolar Macrophages

The enzyme tartrate resistant acid phosphatase (TRAP, two isoforms 5a and 5b) is highly expressed in alveolar macrophages, but its function there is unclear and potent selective inhibitors of TRAP are required to assess functional aspects of the protein. We found higher TRAP activity/expression in lungs of patients with chronic obstructive pulmonary disease (COPD) and asthma compared to controls and more TRAP activity in lungs of mice with experimental COPD or asthma. Stimuli related to asthma and/or COPD were tested for their capacity to induce TRAP. Receptor activator of NF-κb ligand (RANKL) and Xanthine/Xanthine Oxidase induced TRAP mRNA expression in mouse macrophages, but only RANKL also induced TRAP activity in mouse lung slices. Several Au(III) coordination compounds were tested for their ability to inhibit TRAP activity and [Au(4,4′-dimethoxy-2,2′-bipyridine)Cl₂][PF₆] (AubipyOMe) was found to be the most potent inhibitor of TRAP5a and 5b activity reported to date (IC50 1.3 and 1.8 μM respectively). AubipyOMe also inhibited TRAP activity in murine macrophage and human lung tissue extracts. In a functional assay with physiological TRAP substrate osteopontin, AubipyOMe inhibited mouse macrophage migration over osteopontin-coated membranes. In conclusion, higher TRAP expression/activity are associated with COPD and asthma and TRAP is involved in regulating macrophage migration.