Heterobimetallic complexes of palladium(II) and platinum(II) bridged by the ligand 5-phenyl-1,3,4-oxadiazole-2-thione

Multi-activity tetracoordinated pallado-oxadiazole thiones as anti-inflammatory, anti-Alzheimer, and anti-microbial agents: Structure, stability and bioactivity comparison with pallado-hydrazides

Herein, we report a comparative study based on structure, thermal and solution stability, and biopotency against lipoxygenase (LOX), butyrylcholinesterase (BChE) and microbes for Pd(II) compounds of N,O,S bearing 5-(C₅H₄XR)-1,3,4-oxadiazole-2-thiones (L') of type [PdL'Cl₂] (P'n) and N,O bearing respective hydrazides (L) of type trans-[PdL₂Cl₂] (Pn) {X = C, R = 4-I, 2-Br, 4-NO₂, 3-NO₂, 2-Cl, 3-Cl (n = 1-6, serially); X = N (n = 7)}. Spectral techniques (IR, EI-MS, NMR) and physicochemical evaluations successfully characterized the new compounds. The L' behaved as bidentate S-N donors bonded through exocyclic sulfur and N-3' nitrogen, while L acted as amino N donors. UV-vis (solution speciation) and thermal degradation profiles consistently confirmed the greater stability for P'n than Pn compounds. These compounds manifested varying degree in vitro potential to inhibit LOX, BChE and several bacteria and fungi, affected mainly by Pd(II) presence, M-L binding mode, nature and position of R, or halo groups electronegativity. Molecular docking with human 5-LOX and BChE further validated the respective experimental inhibition findings and explored several putative mechanistic interactions (H-bonding, π-stacking, π-alkyl, π-S, etc.) at the enzyme active sites. Pn generally offered superior antimicrobial and anti-LOX (anti-inflammatory) potential than respective P'n compounds, with P3/P'5, P(2,3,7)/P'3, and P6 being comparable, better and equivalent to ampicillin, nystatin and baicalein, the reference antibacterial, antifungal and anti-LOX drugs, respectively. Contrarily, the anti-BChE activity of P'n was found better than Pn compounds, showing P'2/P1 as the most promising anti-Alzheimer drug candidates. This study bares important structural and mechanistic aspects in optimizing antimicrobial, anti-inflammatory and anti-Alzheimer activities, highlighting some potential future pallado-drug candidates.

Crystal structure of 5-(furan-2-yl)-N-phenyl-1,3,4-oxa-diazol-2-amine

The title compound, C12H9N3O2, was obtained as a cyclized oxa-diazole derivative from substituted thio-semicarbazide in the presence of manganese(II) acetate. The furan ring is disordered over two orientations, with occupancies of 0.76 (2) and 0.24 (2). The dihedral angles between the central oxa-diazole ring and the pendant phenyl ring and furan ring (major disorder component) are 3.34 (18) and 5.7 (6)°, respectively. A short intra-molecular C-H⋯O contact generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate R 2 (2)[8] loops. The dimers are linked by C-H⋯π and π-π inter-actions [range of centroid-centroid distances = 3.291 (2)-3.460 (8) Å], generating a three-dimensional network.

Platinum and palladium-triazole complexes as highly potential antitumor agents

The palladium complexes [(dppe)Pd(L)(2)PdCl(2)], [(dppe)Pd(L)(2)PtCl(2)], [(dppp)Pd(L)(2)PdCl(2)], [(dppm) Pd(L)(2)NiCl(2)], and [(dppm)Pd(L)(2)SnCl(4)] 15-19 were prepared. The antiproliferative activity of the newly synthesized complexes as well as their previously prepared analogues 3-14 and 20-26 were screened against a large panel of human cancer cell lines derived from haematological CD4(+) human T-cells containing an integrated HTLV-1 genome (MT-4). The complex 12a, b exhibited remarkable antiproliferative activity against MT-4, CD4(+) human acute T-lymphoblastic leukemia (CCRF-CEM), human splenic B-lymphoblastoid cells (WIL-2NS), human acute B-lymphoblastic leukemia (CCRF-SB), skin melanoma (SK-MEL-28), and prostate carcinoma (DU145) cell lines (CC(50 )= 0.5 microM, 0.4 +/- 0.05 microM, 0.6 +/- 0.05 microM, 0.4 +/- 0.1 microM, and 0.8 +/- 0.2 microM, respectively), meanwhile, 9a, b, 14a, b, and 23 showed significant activity against the CCRF-SB cell lines (CC(50) = 0.6 +/- 0.06 microM, 0.7 +/- 0.05 microM, 0.6 +/- 0.05 microM, and 0.8 +/- 0.15 microM, respectively). Further, 19 exhibited activity against the CCRF-CEM cell line (CC(50 )= 0.4 +/- 0.05 microM).