Syntheses, structural characterization and evaluation of the anti-tubercular activity of copper (II) complexes containing 3-methoxysalicylaldehyde-4-methylthiosemicarbazone

Novel thiosemicarbazide-based β-carboline derivatives as α-glucosidase inhibitors: Synthesis and biological evaluation

In the quest for potent α-glucosidase inhibitors to combat diabetes, a series of novel thiosemicarbazide-based β-carboline derivatives (CTL1∼36) were synthesized and evaluated. CTL1∼36 exhibited remarkable inhibitory effects against α-glucosidase, with IC50 values ranging from 2.81 to 12.40 μM, significantly surpassing the positive control acarbose (IC50 = 564.28 μM). Notably, CTL26 demonstrated the most potent inhibition (IC50 = 2.81 μM) and was characterized as a non-competitive inhibitor. Through a combination assay with fluorescence quenching, 3D fluorescence spectra, CD spectra, and molecular docking, we elucidated that CTL26 formed a complex with α-glucosidase via hydrogen bondings and hydrophobic interactions, leading to α-glucosidase conformation changes that impaired enzymatic activity. In vivo studies revealed that oral administration of CTL26 (25 and 50 mg/kg/d) reduced fasting blood glucose levels, enhanced glucose tolerance, and ameliorated lipid abnormalities in diabetic mice. These findings positioned CTL26 as a promising candidate for the development of α-glucosidase inhibitors with anti-diabetic potential.

Synthesis and Characterization of Copper(II) and Nickel(II) Complexes with 3-(Morpholin-4-yl)propane-2,3-dione 4-Allylthiosemicarbazone Exploring the Antibacterial, Antifungal and Antiradical Properties

The eleven new copper(II) and nickel(II) coordination compounds [Cu(L)Br]2 (1), [Cu(L)Cl] (2), [Cu(L)NO3] (3), [Ni(L)Cl] (4), [Ni(HL)2](NO3)2 (5), and [Cu(A)(L)]NO3, where A is 1,10-phenanthroline (6), 2,2'-bipyridine (7), 3,4-dimethylpyridine (8), 3-methylpyridine (9), pyridine (10) and imidazole (11) were synthesized with 3-(morpholin-4-yl)propane-2,3-dione 4-allylthiosemicarbazone (HL). The new thiosemicarbazone was characterized by NMR and FTIR spectroscopy. All the coordination compounds were characterized by elemental analysis and FTIR spectroscopy. Also, the crystal structures of HL and complexes 1, 6, 7, and 11 were determined using single-crystal X-ray diffraction analysis. Complex 1 has a dimeric molecular structure with two bromide bridging ligands, while 6, 7, and 11 are ionic compounds and comprise monomeric complex cations. The studied complexes manifest antibacterial and antifungal activities and also have an antiradical activity that, in many cases, surpasses the activity of trolox, which is used as a standard antioxidant in medicine. Copper complexes 1-3 have very weak antiradical properties (IC50 > 100 µM), but nickel complexes 4-5 are strong antiradicals with IC50 values lower than that of trolox. The mixed ligand copper complexes with additional ligand of N-heteroaromatic base are superior to complexes without these additional ligands. They are 1.4-5 times more active than trolox.

Synthesis, Structure, and Biologic Activity of Some Copper, Nickel, Cobalt, and Zinc Complexes with 2-Formylpyridine N4-Allylthiosemicarbazone

A series of zinc(II) ([Zn(H₂O)(L)Cl] (1)), copper (II) ([Cu(L)Cl] (2), [Cu(L)Br] (3), [Cu₂(L)₂(CH₃COO)₂]·4H₂O (4)), nickel(II) ([Ni(HL)₂]Cl₂·H₂O (5)), and cobalt(III) ([Co(L)₂]Cl (6)) complexes were obtained with 2-formylpyridine N⁴-allylthiosemicarbazone (HL). In addition another two thiosemicarbazones (3-formylpyridine N⁴-allylthiosemicarbazone (HL^a) and 4-formylpyridine N⁴-allylthiosemicarbazone (HL^b)) have been obtained. The synthesized thiosemicarbazones have been studied using ¹H and ¹³C NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis. The composition and structure of complexes were studied using elemental analysis, IR and UV-Vis spectroscopies, molar conductivity, and magnetic susceptibility measurements. Single crystal X-ray diffraction analysis elucidated the structure of thiosemicarbazones HL, HL^a, and HL^b, as well as complexes 4 and 5. The antiproliferative properties of these compounds toward a series of cancer cell lines (HL-60, HeLa, BxPC-3, RD) and a normal cell line (MDCK) have been investigated. The nickel complex shows high selectivity (SI > 1000) toward HL-60 cell line and is the least toxic. The zinc complex shows the highest selectivity toward RD cell line (SI = 640). The copper complexes (2–4) are the most active molecular inhibitors of proliferation of cancer cells, but exhibit not such a high selectivity and are significantly more toxic. Zinc and copper complexes manifest high antibacterial activity. It was found that calculated at B3LYP level of theory different reactivity descriptors of studied compounds strongly correlate with their biological activity.