ONO‐Pincer‐Type Coumarin‐Based Copper(II) Metalates: Effect on Alzheimer's Disease Pathologies in Caenorhabditis elegans

Abstract

Four copper(II) complexes 1-4 of 3-acetylchromene-2-one and substituted 3-acetylchromene-2-one derived Schiff bases were synthesized and structurally characterized using analytical and spectral techniques. The molecular structure of complex 1 has been confirmed by single crystal X-ray diffraction studies, which revealed that ligand 3-acetylchromene-2-one-4 N-semicarbazone is coordinated to the metal as ONO pincer type ligand. Two nitrate molecules are coordinated to the copper ion through oxygen atoms, of which one nitrate molecule was found to coordinate via two oxygen atoms, thereby achieving six-coordination. Preliminary biological studies like DNA and protein binding analyses indicated the binding of the ligands and complexes to CT-DNA (Calf Thymus DNA) and BSA (Bovine Serum Albumin). We investigated the effects of complexes 1-4 against amyloid-β (Aβ) toxicity using transgenic Caenorhabditis elegans strains expressing muscle-and neuronal-specific human Aβ 1-42 . The results showed that the complexes 2-4 remarkably reduced the Aβ-induced paralysis phenotype, Aβ plaque deposition, and other Alzheimer's disease-associated functional deficits in C. elegans by their potent antioxidant and antiaggregative properties. Complexes 2-4 delayed Alzheimer's disease pathologies, providing a basis for further investigating these effects on higher models.

Coumarin‐Oxazolyl‐Based Chemosensor for Selective Detection of Fe2+ Ions: Preparation, Spectral Characterization, Theoretical Studies and Cellular Bioimaging

“…In the AOX‐Fe 2+ system, multiplet (appeared as broad) observed at δ 7.35–7.64 ppm indicated the presence of coumarin ring protons of the probe. In the AOX‐Fe 2+ IR spectrum (Figure S13), the C=O and C=N groups stretching frequency of AOX decreased from 1759 cm −1 to 1668 cm −1 and 1600 cm −1 to 1561 cm −1 respectively [42] . The obtained results suggested the coordination of oxygen and nitrogen atoms to the Fe 2+ ion.…”

“…In the AOX-Fe 2 + IR spectrum (Figure S13), the C=O and C=N groups stretching frequency of AOX decreased from 1759 cm À 1 to 1668 cm À 1 and 1600 cm À 1 to 1561 cm À 1 respectively. [42] The obtained results suggested the coordination of oxygen and nitrogen atoms to the Fe 2 + ion. Based on literature, it was found that the iron complexes undergo coordination with Schiff bases resulting in the formation of stable five or six coordinated complexes.…”

Preparation of new organo-ruthenium(ii) complexes and their nucleic acid/albumin binding efficiency and in vitro cytotoxicity studies

“…The band appeared at 1542 and 1527 cm −1 corresponding to ν (CN) in the ligands AFIZ and BFIZ respectively was shifted to 1511 and 1521 cm −1 in the complexes PRAFIZ and PRBFIZ indicating the coordination of azomethine nitrogen to ruthenium ions. 39 In the ligands, the bands at 1648 and 1671 cm −1 corresponding to the presence of ν (CO) disappeared in the complexes and a new band appeared at 1371 and 1373 cm −1 corresponding to ν (C–O) indicating the coordination of the ligands through the enolic oxygen atom of the ligands to ruthenium ions (Table S1†). 40,41 Electronic spectra of the ligands ( AFIZ , BFIZ ) and their corresponding Ru( ii ) complexes ( PRAFIZ , PRBFIZ ) were recorded in methanol (10 μM) in the range of 200–800 nm (Fig.…”

Various coordination modes of new coumarin Schiff bases toward Cobalt (III) ion: Synthesis, spectral characterization, in vitro cytotoxic activity, and investigation of apoptosis

“…The characteristic absorption band due to nitrate was also observed for the complexes ( Co1 ‐ Co4 ) at 1382–1384 cm −1. [ [ 29 ] ]…”

“…[ 25,28 ] A bands appeared around 3043–3066 and 1669–1714 cm −1 due to the vibration of the –NH and C=O group of semicarbazone moiety present in the ligands, HL 1 and HL 3 these bands disappeared completely in the complexes Co1 and Co3 , and a new band appeared at 1294–1309 cm −1 corresponding to a possible νC − O vibration, indicating the coordination of oxygen atom after enolization followed by deprotonation. [ 29 ] The bands appeared around 3141–3239 cm −1 and 833–840 cm‐1 due to the vibration of the –NH and C=S group present in the ligands HL 2 and HL 4 which disappeared in the spectra of the complexes Co2 and Co4 and a new band for C‐S appeared at 703–707 cm −1 indicating that the coordination is through the thiolate sulfur after enolisation followed by deprotonation on sulfur. [ 30–33 ] In the complexes Co1 and Co3 the band appeared at 3355–3357 cm −1 due to the vibration of the ‐OH group of water moiety.…”