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Molecules (Basel, Switzerland) Dec 2023Schiff bases (imine or azomethine -N=CH-), which were first obtained by a German chemist, H [...].
Schiff bases (imine or azomethine -N=CH-), which were first obtained by a German chemist, H [...].
PubMed: 38138480
DOI: 10.3390/molecules28247990 -
International Journal of Molecular... Jul 2023As stated by two of the seven papers [...].
As stated by two of the seven papers [...].
Topics: Coordination Complexes; Schiff Bases; Ligands
PubMed: 37446197
DOI: 10.3390/ijms241311014 -
IUCrData Mar 2024The title Si complex, CHNOSi, is built up by a tridentate dinegative Schiff base ligand bound to a sila-cyclo-hexane unit. The coordination geometry of the...
The title Si complex, CHNOSi, is built up by a tridentate dinegative Schiff base ligand bound to a sila-cyclo-hexane unit. The coordination geometry of the penta-coordinated Si atom is a distorted trigonal bipyramid. The presence of the sila-cyclo-hexane ring in the complex leads to an unusual coordination geometry of the Si atom with the N atom from the Schiff base ligand and an alkyl-C atom in apical positions of the trigonal bipyramid. There is a disorder of the methyl group at the imine bond with two orientations resolved for the H atoms [major orientation = 0.55 (3)]. In the crystal, C-H⋯O inter-actions are found within corrugated layers of mol-ecules parallel to the plane.
PubMed: 38586525
DOI: 10.1107/S2414314624002281 -
BioEssays : News and Reviews in... Sep 2023The photocycle of visual opsins is essential to maintain the light sensitivity of the retina. The early physical observations of the rhodopsin photocycle by Böll and... (Review)
Review
The photocycle of visual opsins is essential to maintain the light sensitivity of the retina. The early physical observations of the rhodopsin photocycle by Böll and Kühne in the 1870s inspired over a century's worth of investigations on rhodopsin biochemistry. A single photon isomerizes the Schiff-base linked 11-cis-retinylidene chromophore of rhodopsin, converting it to the all-trans agonist to elicit phototransduction through photoactivated rhodopsin (Rho*). Schiff base hydrolysis of the agonist is a key step in the photocycle, not only diminishing ongoing phototransduction but also allowing for entry and binding of fresh 11-cis chromophore to regenerate the rhodopsin pigment and maintain light sensitivity. Many challenges have been encountered in measuring the rate of this hydrolysis, but recent advancements have facilitated studies of the hydrolysis within the native membrane environment of rhodopsin. These techniques can now be applied to study hydrolysis of agonist in other opsin proteins that mediate phototransduction or chromophore turnover. In this review, we discuss the progress that has been made in characterizing the rhodopsin photocycle and the journey to characterize the hydrolysis of its all-trans-retinylidene agonist.
Topics: Humans; Rhodopsin; Photophobia; Retinaldehyde; Retina
PubMed: 37454357
DOI: 10.1002/bies.202300068 -
Acta Crystallographica. Section E,... Feb 2024The ()-(+)-1-(4-bromo-phen-yl)--[(4-methoxyphen-yl)methyl-idene]ethyl-amine ligand, CHBrNO, (I), was synthesized through the reaction of 4-meth-oxy-anisaldehyde with...
()-(+)-1-(4-Bromo-phen-yl)--[(4-methoxyphen-yl)methyl-idene]ethyl-amine and bis-{()-(+)-1-(4-bromo-phen-yl)--[(4-methoxyphen-yl)methyl-idene]ethyl-amine-κ}di-chlorido-palladium(II).
The ()-(+)-1-(4-bromo-phen-yl)--[(4-methoxyphen-yl)methyl-idene]ethyl-amine ligand, CHBrNO, (I), was synthesized through the reaction of 4-meth-oxy-anisaldehyde with ()-(-)-1-(4-bromo-phen-yl)ethyl-amine. It crystallizes in the ortho-rhom-bic space group 222 belonging to the Sohncke group, featuring a single mol-ecule in the asymmetric unit. The refinement converged successfully, achieving an factor of 0.0508. The Pd com-plex bis-{()-(+)-1-(4-bromo-phen-yl)--[(4-methoxyphen-yl)methyl-idene]ethyl-amine-κ}di-chlorido-pal-ladium(II), [PdCl(CHBrNO)], (II), crystallizes in the monoclinic space group 2 belonging to the Sohncke group, with two mol-ecules in the asymmetric unit. The central atom is tetra-coordinated by two N atoms and two Cl atoms, resulting in a square-planar configuration. The imine moieties exhibit a configuration around the Pd centre, with average Cl-Pd-N angles of approximately 89.95 and 90°. The average distances within the palladium com-plex for the two mol-ecules are ∼2.031 Å for Pd-N and ∼2.309 Å for Pd-Cl.
PubMed: 38333132
DOI: 10.1107/S2056989024000690 -
Molecules (Basel, Switzerland) Oct 2023Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review... (Review)
Review
Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review investigates the techniques and approaches used to strengthen the sensitivity and selectivity of Schiff base fluorescent chemosensors designed specifically to detect toxic and heavy metal cations. The paper explores a range of strategies, including functional group variations, structural modifications, and the integration of nanomaterials or auxiliary receptors, to amplify the efficiency of these chemosensors. By improving selectivity towards targeted cations and achieving heightened sensitivity and detection limits, consequently, these strategies contribute to the advancement of accurate and efficient detection methods while increasing the range of end-use applications. The findings discussed in this review offer valuable insights into the potential of leveraging Schiff base fluorescent chemosensors for the accurate and reliable detection and monitoring of heavy metal cations in various fields, including environmental monitoring, biomedical research, and industrial safety.
Topics: Schiff Bases; Metals, Heavy; Fluorescent Dyes; Cations; Environmental Monitoring
PubMed: 37836803
DOI: 10.3390/molecules28196960 -
Foods (Basel, Switzerland) Jul 2023The aim of the present work was to fabricate Schiff base compounds between chitosan and aldehydes and use the resultant aldehyde-chitosan Schiff bases for broccoli...
The aim of the present work was to fabricate Schiff base compounds between chitosan and aldehydes and use the resultant aldehyde-chitosan Schiff bases for broccoli preservation. Using an element analyzer, the degree of substitution was calculated as 68.27-94.65%. The aldehyde-chitosan Schiff bases showed acidic sensitivity to rapid hydrolysis for releasing aldehyde at a buffer solution of pH 4-6, in which more than 39% of the aldehydes were released within 10 h. The release of aldehydes endows the aldehyde-chitosan Schiff bases with a better antibacterial activity at pH 5 than at pH 7. In a simulated CO (5-15%) atmosphere with high humidity (92%), the hydrolysis of imine bonds (C=N) was triggered and continuously released aldehyde, even without direct contact with the aqueous phase. The application of aldehyde-chitosan Schiff bases significantly extended the shelf life of broccoli from 4 d to 5-7 d and decreased the weight loss of broccoli during storage. In summary, the fabrication of aldehyde-chitosan Schiff bases and the strategy of using pH-response imine bond (C=N) hydrolysis (thus releasing aldehyde to kill microorganisms) were feasible for use in developing EO-incorporated intelligent food packages for vegetable preservation.
PubMed: 37569191
DOI: 10.3390/foods12152921 -
Molecules (Basel, Switzerland) Apr 2024Since the discovery of cisplatin in the 1960s, the search for metallo-drugs that are more efficient than platinum complexes with negligible side effects has attracted... (Review)
Review
Since the discovery of cisplatin in the 1960s, the search for metallo-drugs that are more efficient than platinum complexes with negligible side effects has attracted much interest. Among the other metals that have been examined for potential applications as anticancer agents is copper. The interest in copper was recently boosted by the discovery of cuproptosis, a recently evidenced form of cell death mediated by copper. However, copper is also known to induce the proliferation of cancer cells. In view of these contradictory results, there is a need to find the most suitable copper chelators, among which Schiff-based derivatives offer a wide range of possibilities. Gathering several metal complexes in a single, larger entity may provide enhanced properties. Among the nanometric objects suitable for such purpose are dendrimers, precisely engineered hyperbranched macromolecules, which are outstanding candidates for improving therapy and diagnosis. In this review article, we present an overview of the use of a particular Schiff base, namely pyridine-imine, linked to the surface of dendrimers, suitable for complexing copper, and the use of such dendrimer complexes in biology, in particular against cancers.
Topics: Copper; Dendrimers; Humans; Pyridines; Antineoplastic Agents; Coordination Complexes; Schiff Bases; Imines; Neoplasms; Animals; Chelating Agents
PubMed: 38675623
DOI: 10.3390/molecules29081800 -
Pharmaceutics Aug 2023Amiodarone is underutilized due to significant off-target toxicities. We hypothesized that targeted delivery to the heart would lead to the lowering of the dose by...
BACKGROUND
Amiodarone is underutilized due to significant off-target toxicities. We hypothesized that targeted delivery to the heart would lead to the lowering of the dose by utilizing a cardiomyocyte-targeting peptide (CTP), a cell-penetrating peptide identified by our prior phage display work.
METHODS
CTP was synthesized thiolated at the N-terminus, conjugated to amiodarone via Schiff base chemistry, HPLC purified, and confirmed with MALDI/TOF. The stability of the conjugate was assessed using serial HPLCs. Guinea pigs (GP) were injected intraperitoneally daily with vehicle (7 days), amiodarone (7 days; 80 mg/kg), CTP-amiodarone (5 days; 26.3 mg/kg), or CTP (5 days; 17.8 mg/kg), after which the GPs were euthanized, and the hearts were excised and perfused on a Langendorff apparatus with Tyrode's solution and blebbistatin (5 µM) to minimize the contractions. Voltage (RH237) and Ca-indicator dye (Rhod-2/AM) were injected, and fluorescence from the epicardium split and was captured by two cameras at 570-595 nm for the cytosolic Ca and 610-750 nm wavelengths for the voltage. Subsequently, the hearts were paced at 250 ms with programmed stimulation to measure the changes in the conduction velocities (CV), action potential duration (APD), and Ca transient durations at 90% recovery (CaTD). mRNA was extracted from all hearts, and RNA sequencing was performed with results compared to the control hearts.
RESULTS
The CTP-amiodarone remained stable for up to 21 days at 37 °C. At ~1/15th of the dose of amiodarone, the CTP-amiodarone decreased the CV in hearts significantly compared to the control GPs (0.92 ± 0.05 vs. 1.00 ± 0.03 ms, = 0.0007), equivalent to amiodarone alone (0.87 ± 0.08 ms, = 0.0003). Amiodarone increased the APD (192 ± 5 ms vs. 175 ± 8 ms for vehicle, = 0.0025), while CTP-amiodarone decreased it significantly (157 ± 16 ms, = 0.0136), similar to CTP alone (155 ± 13 ms, = 0.0039). Both amiodarone and CTP-amiodarone significantly decreased the calcium transients compared to the controls. CTP-amiodarone and CTP decreased the CaTD to an extent greater than amiodarone alone ( < 0.001). RNA-seq showed that CTP alone increased the expression of DHPR and SERCA2a, while it decreased the expression of the proinflammatory genes, NF-kappa B, TNF-α, IL-1β, and IL-6.
CONCLUSIONS
Our data suggest that CTP can deliver amiodarone to cardiomyocytes at ~1/15th the total molar dose of the amiodarone needed to produce a comparable slowing of CVs. The ability of CTP to decrease the AP durations and CaTD may be related to its increase in the expression of Ca-handling genes, which merits further study.
PubMed: 37631321
DOI: 10.3390/pharmaceutics15082107 -
IUCrData Sep 2023In the title compound, CHClN, the mol-ecule exists in an configuration with respect to the C=N bond of the Schiff base fragment. The dihedral angle between the indole...
In the title compound, CHClN, the mol-ecule exists in an configuration with respect to the C=N bond of the Schiff base fragment. The dihedral angle between the indole ring system and the benzene ring is 80.86 (12)°. In the crystal, mol-ecules are connected by N-H⋯N hydrogen bonds, generating a (7) chain extending along the -axis direction. No aromatic π-π stacking occurs but weak C-H⋯π inter-actions are observed.
PubMed: 37818473
DOI: 10.1107/S2414314623007800