Active Bromoaniline-Aldehyde Conjugate Systems and Their Complexes as Versatile Sensors of Multiple Cations with Logic Formulation and Efficient DNA/HSA-Binding Efficacy: Combined Experimental and Theoretical Approach

Copper-assisted anticancer activity of hydroxycinnamic acid terpyridine conjugates on triple-negative breast cancer

The development of active therapeutic agents to treat highly metastatic cancer while minimizing damage to healthy cells is of utmost importance. Due to potential antioxidant properties, hydroxycinnamic acid derivatives (caffeic acid and p-coumaric acids) were found to inhibit highly metastatic breast cancer cell growth both in vitro and in vivo without much effect on normal cells. Especially due to the structure-activity relationships, ester and amide derivatives of hydroxycinnamic acids are reported to gain much higher radical scavenging ability than their naked hydroxycinnamic acid analogs like caffeic acid and p-coumaric acid. These results prompted us to design a set of ligands by incorporating an amide moiety on caffeic acid and p-coumaric acid to achieve the least toxicity towards healthy cell lines. Further, the Cu(II) complexes of amide-coupled caffeic acid and p-coumaric acid ligands have been explored for their therapeutic activity on triple-negative breast cancer and other cancer cells like colon, and prostate cancer. The Cu(II) complexes (4 & 5) were characterized by UV-Vis spectroscopy, FTIR, and X-band EPR spectroscopy. The trigonal bipyramidal geometry of complexes was confirmed by the X-band EPR spectra recorded in solution state at liquid N2 temperature. The purity of the complexes was determined by elemental analysis and HPLC traces. Initially, Calf thymus DNA (ct-DNA) binding studies with the complexes were explored. The results suggested the complexes (4 & 5) bind majorly through an intercalative mode of binding with ct-DNA, whereas no significant binding was observed for the bare organic ligands (2 & 3). The intercalation binding modes of 4 and 5 were further supported by UV-visible spectroscopy, ct-DNA melting point analysis, and CD spectroscopy. Moreover, these complexes showed better activity towards cisplatin-resistant TNBC cell lines (4T1, a TNBC cell line derived from the mammary gland tissue of a mouse). The combination of antioxidants and Cu(II) as the metal center made the complexes more cytotoxic toward cancer cell lines (4T1) (IC50 ∼ 3.5 ± 2.5 μM) and the least toxic toward healthy cells (L929) (IC50 ∼ 15 ± 5 μM). Finally, the mechanism of cell death was studied using JC-1 staining and a cell colony formation assay. These studies might help in designing safer anticancer drugs for treating more aggressive types of cancer.

4″-Alkyl EGCG Derivatives Induce Cytoprotective Autophagy Response by Inhibiting EGFR in Glioblastoma Cells

Epidermal growth factor receptor (EGFR)-targeted therapy has been proven vital in the last two decades for the treatment of multiple cancer types, including nonsmall cell lung cancer, glioblastoma, breast cancer and head and neck squamous cell carcinoma. Unfortunately, the majority of approved EGFR inhibitors fall into the drug resistance category because of continuous mutations and acquired resistance. Recently, autophagy has surfaced as one of the emerging underlying mechanisms behind resistance to EGFR-tyrosine kinase inhibitors (TKIs). Previously, we developed a series of 4″-alkyl EGCG (4″-Cn EGCG, n = 6, 8, 10, 12, 14, 16, and 18) derivatives with enhanced anticancer effects and stability. Therefore, the current study hypothesized that 4″-alkyl EGCG might induce cytoprotective autophagy upon EGFR inhibition, and inhibition of autophagy may lead to improved cytotoxicity. In this study, we have observed growth inhibition and caspase-3-dependent apoptosis in 4″-alkyl EGCG derivative-treated glioblastoma cells (U87-MG). We also confirmed that 4″-alkyl EGCG could inhibit EGFR in the cells, as well as mutant L858R/T790M EGFR, through an in vitro kinase assay. Furthermore, we have found that EGFR inhibition with 4″-alkyl EGCG induces cytoprotective autophagic responses, accompanied by the blockage of the AKT/mTOR signaling pathway. In addition, cytotoxicity caused by 4″-C10 EGCG, 4″-C12 EGCG, and 4″-C14 EGCG was significantly increased after the inhibition of autophagy by the pharmacological inhibitor chloroquine. These findings enhance our understanding of the autophagic response toward EGFR inhibitors in glioblastoma cells and suggest a potent combinatorial strategy to increase the therapeutic effectiveness of EGFR-TKIs.

Syntheses, Structural Characterization, and Cytotoxicity Assessment of Novel Mn(II) and Zn(II) Complexes of Aroyl-Hydrazone Schiff Base Ligand

This work describes the syntheses, structural characterization, and biological profile of Mn(II)- and Zn(II)-based complexes 1 and 2 derived from the aroyl-hydrazone Schiff base ligand (L1). The synthesized compounds were thoroughly characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), UV-vis, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction (s-XRD). Density functional theory (DFT) studies of complexes 1 and 2 were performed to ascertain the structural and electronic properties. Hirshfeld surface analysis was used to investigate different intermolecular interactions that define the stability of crystal lattice structures. To ascertain the therapeutic potential of complexes 1 and 2, in vitro interaction studies were carried out with ct-DNA and bovine serum albumin (BSA) using analytical and multispectroscopic techniques, and the results showed more avid binding of complex 2 than complex 1 and L1. The antioxidant potential of complexes 1 and 2 was examined against the 2,2-diphenyl picrylhydrazyl (DPPH) free radical, which revealed better antioxidant ability of the Mn(II) complex. Moreover, the antibacterial activity of synthesized complexes 1 and 2 was tested against Gram-positive and Gram-negative bacteria in which complex 2 demonstrated more effective bactericidal activity than L1 and complex 1 toward Gram-positive bacteria. Furthermore, the in vitro cytotoxicity assessment of L1 and complexes 1 and 2 was carried out against MDA-MB-231 (triple negative breast cancer) and A549 (lung) cancer cell lines. The cytotoxic results revealed that the polymeric Zn(II) complex exhibited better and selective cytotoxicity against the A549 cancer cell line as was evidenced by its low IC₅₀ value.

Electrochemical and fluorescence sensing performance of four new coordination polymers tuned by different metal ions and dicarboxylic acids

Four new ZnII, CdII, CoII, and NiII coordination polymers (CPs) were successfully prepared from a bis-pyridyl–bis-amide and various dicarboxylate mixed ligands, which show good electrochemical and fluorescence sensing performance.

Stable Zinc(II) Coordination Polymer as a Rapid and Highly Sensitive Fluorescence Sensor for the Discriminative Sensing of Biomarker 2-(2-Methoxyethoxy) Acetic Acid

A novel two-dimensional bilayer Zn-based luminescent coordination polymer (LCP) [Zn₂(μ₂-OH)(4-dptp)(3,4',5-bpt)] (LCP 1) [4-dptp = N³,N⁴-bis(pyridin-4-ylmethyl)thiophene-3,4-dicarboxamide and 3,4',5-H₃bpt = biphenyl-3,4',5-tricarboxylic acid] was successfully prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and luminescence spectroscopy. LCP 1 displayed excellent fluorescence-quenching efficiency toward a biomarker 2-(2-methoxyethoxy) acetic acid (MEAA) with a high K_sv (5.153 × 104 M^-1), a low limit of detection (0.244 μM), and a rapid response time (28 s). Additionally, LCP 1 can repeatedly detect MEAA at least eight times with excellent stability. The sensing mechanism was also carefully investigated through UV-vis absorption spectroscopy, density functional theory calculations, and fluorescence lifetime analysis.