Synthesis and evaluation of bifunctional chelating agents derived from bis(2-aminophenylthio)alkane for radioimaging with 99mTc

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

A novel hemicucurbituril-based macrocycle, alternately consisting of amidobenzene and 2-imidazolidione moieties was designed and synthesized. Based on the fragment coupling strategy, nitrobenzene-containing hemicucurbituril was firstly prepared facilely under alkaline environment, and reduction of the nitro groups produced the desired amidobenzene-containing hemicucurbituril. As an original fluorescent chemosensor, it exhibited strong interactions with Fe³⁺ over other metal cations. The experimental evidence of fluorescence spectra suggested that a 1:1 complex was formed between this macrocycle and Fe³⁺ with an association constant up to (2.1 ± 0.3) × 10⁴ M⁻¹. Meanwhile, this macrocycle showed no obvious or only slight enhancement of the fluorescence intensity with selected anions.

NSSN-Type Group 4 Metal Complexes in the Ring-Opening Polymerization of l-Lactide

A new class of zirconium and hafnium complexes coordinated by linear dianonic tetradentate NSSN ligands is reported. The ligands feature two amide functions coupled with two thioether groups linked by a central flexible ethane bridge and two lateral rigid phenylene bridges and differ for the substituents on the aniline nitrogen atoms, i.e., isopropyl, cyclohexyl, or mesityl substituents: NSSN-iPr, NSSN-Cy, or NSSN-Mes. They were prepared by reacting 2-aminothiophenol with dibromoethane to afford the NSSN ligands without substituents on the aniline nitrogen atoms, which were subsequently alkylated through a reductive amination of acetone or cyclohexanone or palladium-catalyzed cross-coupling reaction with mesityl bromide. The corresponding zirconium and hafnium complexes 1-5 were obtained through a transamination reaction between the neutral ligands and Zr(NMe₂)₄ or Hf(NMe₂)₄ [(NSSN-iPr)Zr(NMe₂)₂ (1), (NSSN-Cy)Zr(NMe₂)₂ (2), (NSSN-Mes)Zr(NMe₂)₂ (3), (NSSN-iPr)Hf(NMe₂)₂ (4), and (NSSN-Cy)Hf(NMe₂)₂ (5)]. They were characterized in solution by NMR spectroscopy and in solid state by X-ray diffraction analysis (except for 3). All complexes present an octahedral coordination geometry with a fac-fac ligand wrapping and a cis relationship between the other two monodentate ligands. The catalytic performances of 1-5 in the ring-opening polymerization of cyclic esters were investigated. Complex 1 was the most active: its polymerization activity was superior to those generally displayed by zirconium complexes featuring OSSO ligands and compared well with those of the most active group 4 complexes operating in a toluene solution.

Novel benzimidazole analogs as inhibitors of EGFR tyrosine kinase

A series of new benzimidazole congeners were synthesized, and their structures were elucidated on the basis of elemental analyses and spectral studies (¹H NMR, FT-IR and EI-MS). Preliminary pharmacokinetic studies showed a promising outlook for further in vivo evaluation. The newly synthesized compounds were tested in vitro on human breast carcinoma cell line (MCF-7) in which EGFR is highly expressed. Most of the tested compounds exhibited antitumor activity with IC₅₀ values in the micro to nano molar range.

Synthesis, characterization and biological activity of Schiff base analogues of indole-3-carboxaldehyde

Eight novel heterocyclic Schiff bases derived from the condensation reactions of indole 3-carboxaldehyde with different l-amino acids (histidine, glutamic acid, aspartic acid, leucine, valine) as well as with some aminophenols, have been synthesized and characterized by various spectroscopic methods (IR, MS, (1)H NMR). Schiff base derivatives of indole 3-carboxaldehyde were labeled with (99m)Tc and radiochemical purity was above 97% which is ascertained by instant thin layer chromatography using different solvent conditions. Stability studies of all the derivatives of indole 3-carboxaldehyde was determined under physiological conditions and were stable for more than 24h. Blood clearance showed a quick wash out from the circulation and biological half life was found to be t((1/2))(F)=1h 15min; t((1/2))(S)=10h 05min. Excellent quality radioimages of tumor bearing mice were recorded showing rapid clearance of background activity, visualization of tumor at 3h and clearance from kidneys of histidine analogue which was further evidenced in biodistribution studies. Antimicrobial activity of these Schiff base compounds was evaluated against Bacillus subtilis, Pseudomonas fluorescence, Staphylococcus aureus, Aspergillus niger, Candida albicans and Trichophyton rubrum.

Synthesis, metal complexation and biological evaluation of a novel semi-rigid bifunctional chelating agent for 99mTc labelling

A novel bifunctional chelating agent bearing an aromatic ring has been synthesised and characterised. This ligand formed well-defined oxorhenium complexes. The analogous 99mTcO-complex was obtained in an excellent yield with high radiochemical purity (>95%). The biodistribution of the 99mTc-complex after intravenous injection studied in normal rats showed that the activity was excreted mainly via renal-urinary pathway indicating its use for labelling peptides with 99mTc.