Synthesis, spectral, NLO studies, and antimicrobial activities of curcumin diketimine metal complexes

Synthesizing Various Organic Polyacid Compounds for Modifying Forward Osmosis Membranes to Enhance Separation Performance

In order to overcome the challenges of low permeate flux (J_p) and the accompanying reverse solute flux (J_S) during the forward osmosis (FO) membrane separation process, we synthesized four hybrid materials of polyacid-based organic compounds and incorporated them into the selective polyamide (PA) layer to make novel thin-film nanocomposite (TFN) FO membranes. The J_p and J_S of each membrane were evaluated and used along with membrane selectivity (J_p/J_S) as indicators of membrane separation performance. The fabricated and modified membranes were also characterized for ridge and valley surface morphologies with increasing hydrophilicity and finger-shaped parallel channels in the PSf substrate. Moreover, two highly hydrophilic nanoparticles of graphene oxide (GO) and titanium oxide (TiO₂) were introduced with the hybrid materials for PA modification, which can further enhance the J_p of the TFN membranes. The highest J_p of the TFN membranes achieved 12.1 L/m²-h using 0.1% curcumin-acetoguanamine @ cerium polyacid (CATCP) and 0.0175% GO. The characteristic peaks of the hybrid materials were detected on the membrane surface using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, evidencing successful incorporation of the hybrid materials during membrane modification. Here, we present the novel TFN membranes using hybrid materials for separation applications. The reactions for synthesizing the hybrid materials and for incorporating them with PA layer are proposed.

A review on biological activities of Schiff base, hydrazone, and oxime derivatives of curcumin

Schiff base, hydrazone, and oxime derivatives of curcumin showed enhanced biological activities.

Biological properties of metal complexes of curcumin

Curcumin, a naturally occurring phenolic compound isolated from Curcuma longa, has different pharmacological effects, including antiinflammatory, antimicrobial, antioxidant, and anticancer properties. However, curcumin has been found to have a limited bioavailability because of its hydrophobic nature, low-intestinal absorption, and rapid metabolism. Therefore, there is a need for enhancing the bioavailability and its solubility in water in order to increase the pharmacological effects of this bioactive compound. One strategy is curcumin complexation with transition metals to circumvent the abovementioned problems. Curcumin can undergo chelation with various metal ions to form metallo-complexes of curcumin, which may show greater effects as compared with curcumin alone. Promising results with metal curcumin complexes have been observed with regard to antioxidant, anticancer, and antimicrobial activity, as well as in treatment of Alzheimer's disease. The present review provides a concise summary of the characterization and biological properties of curcumin-metal complexes. © 2019 BioFactors, 45(3):304-317, 2019.

Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety

Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and (1)H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

Formation of curcumin molecular ion under electrospray ionisation conditions in the presence of metal cations

Electrospray ionisation (ESI) mass spectra obtained for solutions containing curcumin, copper cation and other metal cations, namely Co2+, Ni2+, Mn2+ and Zn2+, have shown an abundant curcumin molecular ion at m/z 368. This ion was not formed for solutions containing curcumin and copper cations or for those containing curcumin and other metal cations. To the best of our knowledge, it is the first example of a system in which copper cations and other metal cations promote formation of organic radical cation under ESI conditions.

Synthesis, spectral characterization and biological activity of metal(II) complexes with 4-aminoantipyrine derivatives

Novel metal(II) complexes derived from furfurylidene-4-aminoantipyrine and 2-aminobenzothiazole were synthesized and characterized by spectroscopic (IR, (1)H NMR, UV-Vis., ESR and DART-MS) and other analytical methods. IR spectral studies indicate the binding sites of the ligand with the metal ion. Molar conductance data and magnetic susceptibility measurements provide evidence for monomeric and neutral nature of the complexes. The X band ESR spectrum of the Cu(II) complex at 300 and 77K was recorded. The electrochemical behaviour of the complexes in MeCN at 298 K was studied. Thermal studies of the ligand and its complexes show the presence of coordinated water in the complexes. The grain size of the complex was calculated by Scherrer formula using powder XRD. The surface morphology of the complexes was studied using SEM. The in vitro biological screening of the ligand and its complexes were tested against bacterial species S. aureus, E. coli, K. pneumoniae, P. vulgaris and P. aeruginosa and fungal species A. niger, R. stolonifer, A. flavus, R. bataicola and C. albicans. The DNA binding and cleavage activity of the ligand and its complexes were studied. Super oxide dismutase (SOD) activities of the ligand and its complexes have also been measured.