A novel cytotoxic cerium complex: aquatrichloridobis(1,10-phenanthroline)cerium(III) (KP776). Synthesis, characterization, behavior in H2O, binding towards biomolecules, and antiproliferative activity

A novel isatin Schiff based cerium complex: synthesis, characterization, antimicrobial activity and molecular docking studies

In this work, a novel isatin-Schiff base L2 had been synthesized through a simple reaction between isatin and 2-amino-5-methylthio-1,3,4-thiadiazole. The produced Schiff base L2 was then subjected to a hydrothermal reaction with cerium chloride to produce the cerium (III)-Schiff base complex C2. Several spectroscopic methods, including mass spectra, FT-IR, elemental analysis, UV-vis, 13C-NMR, 1H-NMR, Thermogravimetric Analysis, HR-TEM, and FE-SEM/EDX, were used to completely characterize the produced L2 and C2. A computer simulation was performed using the MOE software program to find out the probable biological resistance of studied compounds against the proteins in some types of bacteria or fungi. To investigate the interaction between the ligand and its complex, we conducted molecular docking simulations using the molecular operating environment (MOE). The docking simulation findings revealed that the complex displayed greater efficacy and demonstrated a stronger affinity for Avr2 effector protein from the fungal plant pathogen Fusarium oxysporum (code 5OD4) than the original ligand. The antibacterial activity of the ligand and its Ce3+ complex were applied in vitro tests against different microorganism. The study showed that the complex was found to be more effective than the ligand.

Loading with Biomolecules Modulates the Antioxidant Activity of Cerium-Doped Bioactive Glasses

In order to identify new bioactive glasses (BGs) with optimal antioxidant properties, we carried out an evaluation of a series of cerium-doped BGs [Ce-BGs─H, K, and mesoporous bioactive glasses (MBGs)] loaded with different biomolecules, namely, gallic acid, polyphenols (POLY), and anthocyanins. Quantification of loading at variable times highlighted POLY on MBGs as the system with the highest loading. The ability to dismutate hydrogen peroxide (catalase-like activity) of the BGs evaluated is strongly correlated with cerium doping, while it is marginally decreased compared to the parent BG upon loading with biomolecules. Conversely, unloaded Ce-BGs show only a marginal ability to dismutate the superoxide anion (SOD)-like activity, while upon loading with biomolecules, POLY in particular, the SOD-like activity is greatly enhanced for these materials. Doping with cerium and loading with biomolecules give complementary antioxidant properties to the BGs investigated; combined with the persistent bioactivity, this makes these materials prime candidates for upcoming studies on biological systems.

Cerium Containing Bioactive Glasses: A Review

Bioactive glasses (BGs) for biomedical applications are doped with therapeutic inorganic ions (TIIs) in order to improve their performance and reduce the side effects related to the surgical implant. Recent literature in the field shows a rekindled interest toward rare earth elements, in particular cerium, and their catalytic properties. Cerium-doped bioactive glasses (Ce-BGs) differ in compositions, synthetic methods, features, and in vitro assessment. This review provides an overview on the recent development of Ce-BGs for biomedical applications and on the evaluation of their bioactivity, cytocompatibility, antibacterial, antioxidant, and osteogenic and angiogenic properties as a function of their composition and physicochemical parameters.

Bone-targeted pH-responsive cerium nanoparticles for anabolic therapy in osteoporosis

Antiresorptive drugs are widely used for treatment of osteoporosis and cancer bone metastasis, which function mainly through an overall inhibition of osteoclast. However, not all osteoclasts are "bone eaters"; preosteoclasts (pOCs) play anabolic roles in bone formation and angiogenesis through coupling with osteoblasts and secreting platelet derived growth factor-BB (PDGF-BB). In this study, a bone-targeted pH-responsive nanomaterial was designed for selectively eliminating mature osteoclasts (mOCs) without affecting pOCs. Biocompatible cerium nano-system (CNS) was guided to the acidic extracellular microenvironment created by mOCs and gained oxidative enzymatic activity. Oxidative CNS decreased the viability of mOCs through accumulating intracellular reactive oxygen species and enhancing calcium oscillation. Non-acid secreting anabolic pOCs were thus preserved and kept producing PDGF-BB, which lead to mesenchymal stem cell osteogenesis and endothelial progenitor cell angiogenesis via PI3K-Akt activated focal adhesion kinase. In treating osteoporotic ovariectomized mice, CNS showed better protective effects compare with the current first line antiresorptive drug due to the better anabolic effects marked by higher level of bone formation and vascularization. We provided a novel anabolic therapeutic strategy in treating bone disorders with excessive bone resorption.

A Ce(iii) complex potently inhibits the activity and expression of tyrosine phosphatase SHP-2

Four new Ce(iii) complexes 1-4 with tridentate NNO-donor Schiff base ligands have been designed and successfully synthesized. These complexes were characterized by elemental analysis, IR, and ESI-MS, with formulas of [Ce(HL1)2(NO3)3]·2CH3OH (1), [Ce(L2)2(NO3)]·3H2O (2), [Ce(HL3)(L3)(NO3)Br]·H2O (3) and [Ce(L4)2(NO3)]·3H2O (4), in which ligands HL1-HL4 are respectively N'-[(1E)-pyridin-2-ylmethylidene]pyrazine-2-carbohydrazide (HL1), 2-(1-(salicyloylhydrazono)ethyl)pyrazine (HL2), N'-[(1E)-pyridin-2-ylmethylidene]pyridine-2-carbohydrazide (HL3) and 2-(1-(salicyloylhydrazono)ethyl) pyridine (HL4). X-ray single crystal diffraction analysis indicates that complex 1 crystallizes in the monoclinic system with the space group C2/c and the structure of complex 1 consists of a monomeric Ce(iii) species with a Ce(iii) moiety bonded to two tridentate Schiff base ligands, three nitrates and solvents. These complexes effectively inhibit the enzyme activities of PTPs (SHP-1, SHP-2, TCPTP and PTP1B), among which complex 3 shows the most potent inhibition of SHP-2 with the lowest IC50 value of 0.61 μM and displays obvious selectivity towards SHP-2. Its inhibition potency against SHP-2 was approximately 17, 4, and 5 fold higher than that against SHP-1, TCPTP and PTP1B, respectively. Further study discloses that complex 3 inhibits SHP-2 in a competitive manner. Fluorescence measurements indicate that complex 3 tightly binds to SHP-2 with a molar ratio of 1 : 1 and a binding constant of 5.45 × 105 M-1. Western blot experiments show that complex 3 promotes the phosphorylation of the SHP-2 substrate by the combination of the inhibition of the activity and expression of SHP-2. Moreover, complex 3 decreases the survival rate of A549 cells to 35.12% at 100 μM and induces apoptosis with an apoptosis rate of 12.06% at 50 μM. All these results suggest that complex 3 is a potential bi-functional inhibitor of the activity and expression of tyrosine phosphatase SHP-2.