Spectro-electrochemical, fluorometric and biothermodynamic evaluation of pharmacologically active morpholine scaffold single crystal ligand and its metal(II) complexes: A comparative study on in-vitro and in-silico screening towards DNA/BSA/SARS-CoV-19

A novel series of metal(II) complexes (1-5) [M^II(L)₂]{Where M = Cu (1), Co (2), Mn (3), Ni (4) and Zn (5)} constructed from 2-(4-morpholinobenzylideneamino)phenol Schiff base ligand (HL) in a 1:2 M ratio and the spectral and analytical results put forward square planar geometry. Spectro-electrochemical, hydrodynamic, gel electrophoresis, and DNA binding/cleavage results for all the compounds demonstrate that complex (1) had excellent DNA binding/cleavage properties compared to other compounds. The observation also suggests that test compounds could intercalate with DNA, and the biothermodynamic property more strongly supports the stabilizing of the double helix DNA with the complexes. BSA binding constant results show that complex (1) exposes the best binding property via a static mode, which is further confirmed by FRET calculations. The DFT calculations and docking results for all compounds towards DNA, BSA and SARS-CoV-19 main protease (3CLPro), reveal the binding energies were in the range of -7.8 to -9.4, -6.6 to -10.2 and - 6.1 - -8.2 kcal/mol for all test compounds respectively. In this case, complexes showed favorable binding energies compared to free ligand, which stimulates further studies aimed at validating the predicted activity as well as contributing to tackling the current and future viral pandemics. The in-vitro antioxidant, antimicrobial, and anticancer results for all compounds revealed that copper complex (1) has better activity compared to others. This might result in an effective anticancer drug for future research, which is especially promising since the observed experimental results for all cases were in close agreement with the theoretical calculations.

Assessment of the biological effect of metal ions and their complexes using Allium cepa and Artemia salina assays: a possible environmental implementation of biological inorganic chemistry

The pollution of aquatic ecosystems due to the elevated concentration of a variety of contaminants, such as metal ions, poses a threat to humankind, as these ecosystems are in high relevance with human activities and survivability. The exposure in heavy metal ions is responsible for many severe chronic and pathogenic diseases and some types of cancer as well. Metal ions of the groups 11 (Cu, Ag, Au), 12 (Zn, Cd, Hg), 14 (Sn, Pb) and 15 (Sb, Bi) highly interfere with proteins leading to DNA damage and oxidative stress. While, the detection of these contaminants is mainly based on physicochemical analysis, the chemical determination, however, is deemed ineffective in some cases because of their complex nature. The development of biological models for the evaluation of the presence of metal ions is an attractive solution, which provides more insights regarding their effects. The present work critically reviews the reports published regarding the toxicity assessment of heavy metal ions through Allium cepa and Artemia salina assays. The in vivo toxicity of the agents is not only dose depended, but it is also strongly affected by their ligand type. However, there is no comprehensive study which compares the biological effect of chemical agents against Allium cepa and Artemia salina. Reports that include metal ions and complexes interaction with either Allium cepa or Artemia salina bio-indicators are included in the review.

Spectro-electrochemical assessments of DNA/BSA interactions, cytotoxicity, radical scavenging and pharmacological implications of biosensitive and biologically active morpholine-based metal(ii) complexes: a combined experimental and computational investigation

Biosensitive and biologically active morpholine-based transition metal(ii) complexes (1-5) were constructed as [MII(L) AcO]·nH2O {where M = Cu (1) n = 1; Co (2), Mn (3), Ni (4), n = 4 and Zn (5) n = 2}, which were synthesized from 2-(-(2-morpholinoethylimino) methyl)-4-bromophenol ligand (HL) and structurally characterized by various analytical and spectroscopic techniques, which proposed a square planar and tetrahedral geometry around the central metal ion with lattice water molecules. The gel electrophoresis results revealed that complexes 1 and 5 had more potent DNA cleavage efficacy in the presence of an oxidizing agent (H2O2) as compared to the others. The observed DNA binding results for all the compounds as determined by spectro-electrochemical and hydrodynamic techniques were in the order 3.36 (1) > 3.06 (2) > 2.73 (4) > 2.61 (5) > 1.84 (3) > 1.00 (HL) × 104 M-1. The obtained bovine serum albumin (BSA) protein binding constant (K b) results put forward the following order 2.38 (1) > 2.21 (2) > 2.18 (5) > 1.76 (4) > 1.40 (3) > 1.26 (HL) × 104 M-1. Also, the biothermodynamic parameters (, , ΔH° and ΔS°) and binding results divulged that all the complexes (1-5) could bind to DNA via intercalation in a spontaneous manner. Density functional theory calculations were employed to optimize the structure of ligand (HL) and its complexes (1-5) to gain insights into their electronic structures. Molecular docking analysis was carried out to identify the preferential binding modes of these complexes toward DNA and BSA protein. The theoretical observations of all cases were found to be very close to the experimental observations. Among the radical scavenging activity results for all the cases toward DPPH, hydroxyl radical, superoxide, nitric oxide and ferric reducing agents, complex (1) revealed a superior scavenging potency over the other compounds. In the screened antimicrobial reports against 10 different selected pathogenic species, although all the complexes (1-5) exhibited a greater significant inhibitory effect than the free ligand, complexes 4 and 5 achieved the best potency over standard drugs. The observed percentage of growth inhibition for all the compounds against the A549, HepG2, MCF-7 and NHDF cell lines suggested that complex 1 had enhanced growth-inhibitory potency over the other compounds and slightly affected normal cells as compared to the standard drug cisplatin, which may lead to its investigation as a promising anticancer agent in future research.

Density functional theory molecular modelling, DNA interactions, antioxidant, antimicrobial, anticancer and biothermodynamic studies of bioactive water soluble mixed ligand complexes

A novel series of bioactive water soluble mixed ligand complexes (1-5) [M^II(L)(phen)AcO]. nH₂O {where M = Cu (1) n = 2; Co (2), Mn (3), Ni (4), n = 4 and Zn (5) n = 2} were synthesized from 2-(2-Morpholinoethylimino) methyl)phenol Schiff base ligand (LH), 1, 10-phenanthroline and metal(II) acetate salt in a 1:1:1 stoichiometric ratio and characterized by several spectral techniques. The obtained analytical and spectral data suggest the octahedral geometry around the central metal ion. Density functional theory calculations have been further supportive to explore the optimized structure and chemical reactivity of these complexes from their frontier molecular orbitals. Gel electrophoresis result indicates that complex (1) manifested an excellent DNA cleavage property than others. The observed binding constants with free energy changes by electronic absorption technique and DNA binding affinity values by viscosity measurements for all compounds were found in the following order (1) > (2) > (4) > (5) > (3) > (LH). The binding results and thermodynamic parameters are described the intercalation mode. In vitro antioxidant properties disclose that complex (1) divulges high scavenging activity against DPPH^•, ^•OH, O₂^-• NO^•, and Fe³⁺. The antimicrobial reports illustrate that the complexes (1-5) were exhibited well defined inhibitory effect than ligand (LH) against the selected different pathogenic species. The observed percentage growth inhibition against A549, HepG2, MCF-7, and NHDF cell lines suggest that complex (1) has exhibited superior anticancer potency than others. Thus, the complex (1) may contribute as potential anticancer agent due to its unique interaction mode with DNA.GRAPHICAL ABSTRACT Communicated by Ramaswamy H. Sarma.