Effect of chirality on the anticancer activity of Pt(II) and Pt(IV) complexes containing 1R,2R and 1S,2S enantiomers of the trans-1,2-diamino-4-cyclohexene ligand (DACHEX), an analogue of diaminocyclohexane used in oxaliplatin

Comparison of click-capable oxaliplatin and cisplatin derivatives to better understand Pt(ii)-induced nucleolar stress

Pt(ii) chemotherapeutic complexes have been used as predominant anticancer drugs for nearly fifty years. Currently there are three FDA-approved chemotherapeutic Pt(ii) complexes: cisplatin, carboplatin, and oxaliplatin. Until recently, it was believed that all three complexes induced cellular apoptosis through the DNA damage response pathway. Studies within the last decade, however, suggest that oxaliplatin may instead induce cell death through a unique nucleolar stress pathway. Pt(ii)-induced nucleolar stress is not well understood and further investigation of this pathway may provide both basic knowledge about nucleolar stress as well as insight for more tunable Pt(ii) chemotherapeutics. Through a previous structure-function analysis, it was determined that nucleolar stress induction is highly sensitive to modifications at the 4-position of the 1,2-diaminocyclohexane (DACH) ring of oxaliplatin. Specifically, more flexible and less rigid substituents (methyl, ethyl, propyl) induce nucleolar stress, while more rigid and bulkier substituents (isopropyl, acetamide) do not. These findings suggest that a click-capable functional group can be installed at the 4-position of the DACH ring while still inducing nucleolar stress. Herein, we report novel click-capable azide-modified oxaliplatin mimics that cause nucleolar stress. Through NPM1 relocalization, fibrillarin redistribution, and γH2AX studies, key differences have been identified between previously studied click-capable cisplatin mimics and these novel click-capable oxaliplatin mimics. These complexes provide new tools to identify cellular targets and localization through post-treatment Cu-catalyzed azide-alkyne cycloaddition and may help to better understand Pt(ii)-induced nucleolar stress. To our knowledge, these are the first reported oxaliplatin mimics to include an azide handle, and cis-[(1R,2R,4S) 4-methylazido-1,2-cyclohexanediamine]dichlorido platinum(ii) is the first azide-functionalized oxaliplatin derivative to induce nucleolar stress.

Chirality influence on the cytotoxic properties of anionic chiral bis(N-heterocyclic carbene)silver complexes

Complexes Na₃[Ag(NHC^R)₂], 2a-e and 2b'-c', where NHC^R is a N-heterocyclic carbene of the 2,2'-(1H-2λ³,3λ⁴-imidazole-1,3-diyl)dicarboxylate type, were prepared by treatment of compounds HL^R, 1a-e and 1b'-c' (2-(1-(carboxyalkyl)-1H-imidazol-3-ium-3-yl)carboxylate), with silver oxide in the presence of aqueous sodium hydroxide. They were characterized by analytical, spectroscopic (infrared, IR, ¹H and ¹³C nuclear magnetic resonance, NMR, and circular dichroism) and X-ray methods (2a). In the solid state, the anionic part of complex 2a, [Ag(NHC^H)₂]^3-, shows a linear disposition of C_carbene-Ag-C_carbene atoms and an eclipsed conformation of the two NHC ligands. The proposed bis(NHC) nature of the silver complexes was maintained in solution according to NMR and density functional theory (DFT) calculations. The cytotoxic activity of compounds 2 was evaluated against four cancer cell lines and one non-cancerous cell line and several structure-activity correlations were found for these complexes. For instance, the activity decreased when the bulkiness of the R alkyl group in Na₃[Ag(NHC^R)₂] increased. More interesting is the detected chirality-anticancer relationship, where complexes Na₃[Ag{(S,S)-NHC^R}₂] (R = Me, 2b; ⁱPr, 2c) showed better anticancer activity than those of their enantiomeric derivatives Na₃[Ag{(R,R)-NHC^R}₂] (R = Me, 2b'; ⁱPr, 2c').

Influence of ring modifications on nucleolar stress caused by oxaliplatin-like compounds

Oxaliplatin, a platinum compound in broad clinical use, can induce cell death through a nucleolar stress pathway rather than the canonical DNA damage response studied for other Pt(II) compounds. Previous work has found that the oxaliplatin 1,2-diaminocyclohexane (DACH) ring but not the oxalate leaving group is important to the ability to induce nucleolar stress. Here we study the influence of DACH ring substituents at the 4-position on the ability of DACH-Pt(II) compounds to cause nucleolar stress. We determine that DACH-Pt(II) compounds with 4-position methyl, ethyl, or propyl substituents induce nucleolar stress, but DACH-Pt(II) compounds with 4-isopropyl substituents do not induce nucleolar stress. This effect is independent of whether the substituent is in the axial or equatorial position relatively to the trans diamines of the ligand. These results suggest that spatially sensitive interactions could be involved in the ability of platinum compounds to cause nucleolar stress.

Stereoselective synthesis of oxime containing Pd(II) compounds: Highly effective, selective and stereo-regulated cytotoxicity against carcinogenic PC-3 cells

New palladium compounds [Pd{(1S,4R)-NOH^NH(R)}Cl2] (R = Ph 1a or Bn 1b), [Pd{(1S,4R)-NOH^NH(R)}{(1S,4R)-NO^NH(R)}][Cl] (R = Ph 2a or Bn 2b) and corresponding [Pd{(1R,4S)-NOH^NH(R)}Cl2] (R = Ph 1a’ or Bn 1b’) and...

Pt(ii) complex containing the 1R,2R enantiomer of trans-1,2-diamino-4-cyclohexene ligand effectively and selectively inhibits the viability of aggressive pancreatic adenocarcinoma cells and alters their lipid metabolism

New compounds structurally derived from oxaliplatin exhibit high potency in malignant pancreatic adenocarcinoma cells. Their mechanism of antiproliferative action in pancreatic cancer cells involves inhibition of de novo lipid synthesis.