Synthesis, experimental and theoretical characterization of tetra dentate N,N'-dipyridoxyl (1,3-propylenediamine) salen ligand and its Co(III) complex

The new tetra dentate dianionic H2PS (N,N'-dipyridoxyl (1,3-propylenediamine)) Schiff-base ligand and its octahedral Co(III) salen complex [Co(PS)(H2O)(CH3OH)]+CH3COO(-) were synthesized, where coordinating atoms of H2PS (N,N,O(-),O(-)) occupied equatorial positions with H2O and CH3OH as axial ligands. The nature of the H2PS and its complex were determined by elemental and spectrochemical (IR, UV-vis, 1H NMR and Mass) analysis. Also, the fully optimized geometries and vibrational frequencies of them together with the 1H NMR chemical shifts of H2PS have been calculated using density functional theory (B3LYP) method. Obtained structural parameters are in good agreement with the experimental data reported for similar compounds. The calculated and experimental results confirmed the suggested structures for the ligand and complex.     

A facile route to diastereomeric phosphorus ylides. Chemoselective synthesis of dialkyl (E)-2-[1-(2-oxocyclopentylidene)ethyl]-2-butenedioates

2-Acetylcyclopentanone undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce dialkyl 2-(1-acetyl-2-oxocyclopentyl)-3-(1,1,1-triphenyl-lambda(5)-phosphanylidene)succinates. These compounds undergo intramolecular Wittig reactions in boiling benzene to produce highly strained spirocyclobutene derivatives, which spontaneously undergo ring-opening reactions to produce dialkyl (E)-2-[1-(2-oxocyclopentyliden)ethyl]-2-butenedioates.     

Electrochemical investigations into Tau protein phosphorylations

Hyperphosphorylation of Tau, a protein that stabilizes microtubules, leads to the breakdown of the microtubular structure and ultimately to the formation of neurofibrillar tangles within neurons. Here, we report monitoring of Tau phosphorylations electrochemically, using Tau protein films chemically linked to gold surfaces and 5'-γ-ferrocenyl (Fc) adenosine triphosphate (Fc-ATP) as a co-substrate. Fc-phosphorylation reactions of Tau are explored using the three protein kinases, glycogen synthase kinase (GSK-3β), sarcoma (Src)-related kinase, and protein kinase A (PKA), which catalyze Fc-phosphorylation of different residues and regions within Tau. The kinetic parameters of the biochemical process (K(M) and V(max)) were determined.     

Development of radiogallium–ethylenecysteamine cysteine complex as a possible renal imaging agent

[⁶⁷Ga]-ethylenecysteamine cysteine ([⁶⁷Ga]ECC) was prepared using freshly prepared [⁶⁷Ga]GaCl₃ and ethylenecysteamine cysteine (ECC) for 30 min at 90 °C (radiochemical purity ≈97 ± 0.88% ITLC, specific activity: 210 ± 5 GBq/mM). Stability of the complex was checked in human serum for 24 h at 37 °C. Partition co-efficient of the tracer in octanol:saline mixture was determined (log P; 0.8). The biodistribution of the radiolabeled compound in vital organs of wild-type rats were compared with that of free Ga³⁺ cation up to 48 h. Initial biodistribution results showed significant kidney excretion of the tracer comparable to that of homologous ^99mTc compound.     

Development of 166Ho bleomycin as a possible therapeutic complex

Due to interesting therapeutic properties of ¹⁶⁶Ho and the antineoblastic antibiotic, bleomycin (BLM), ¹⁶⁶Ho-bleomycin (¹⁶⁶Ho-BLM) was developed as a possible therapeutic compound. ¹⁶⁶Ho chloride was obtained by thermal neutron irradiation (1 × 10¹³ n cm^?2 s^?1) of natural Ho(NO₃)₃ samples (specific activity = 3–5 GBq mg^?1), dissolved in acidic media. At optimized conditions (room temperature, 12 h, 0.15–0.3 mg bleomycin for 74 MBq ¹⁶⁶HoCl₃) a radiochemical purity of 94–97% was obtained as shown by ITLC and HPLC (specific activity, 700–740 GBq mmol^?1). Biodistribution studies of ¹⁶⁶Ho chloride and ¹⁶⁶Ho-BLM were performed in wild-type rats. The accumulation of the radiolabeled compound in lungs, liver and spleen demonstrates a similar pattern to the other radiolabeled bleomycins.