Although ferrocene derivatives have attracted considerable attention as possible anticancer agents, the medicinal potential of diiron complexes has remained largely unexplored. Herein, we describe the straightforward multigram‐scale synthesis and the antiproliferative activity of a series of diiron cyclopentadienyl complexes containing bridging vinyliminium ligands. IC50 values in the low‐to‐mid micromolar range were determined against cisplatin sensitive and resistant human ovarian carcinoma (A2780 and A2780cisR) cell lines. Notable selectivity towards the cancerous cells lines compared to the non‐tumoral human embryonic kidney (HEK‐293) cell line was observed for selected compounds. The activity seems to be multimodal, involving reactive oxygen species (ROS) generation and, in some cases, a fragmentation process to afford monoiron derivatives. The large structural variability, amphiphilic character and good stability in aqueous media of the diiron vinyliminium complexes provide favorable properties compared to other widely studied classes of iron‐based anticancer candidates.
Silver nanoparticles (AgNPs) have been intensively investigated in virtue of their optical and antimicrobial properties, although their applications have been limited due to inherent toxicity and to the need of employing harsh chemical reagents for the synthesis. In this work, ulvan, a sulfated polysaccharide extracted from green algae belonging to Ulva armoricana sp., was for the first time investigated and identified as reducing and stabilizing agent for AgNPs synthesis by using milder conditions than those conventionally adopted by chemical methods. The synthesized AgNPs were thoroughly characterized to highlight the structure and the role exerted by ulvan in their synthesis and stabilization. The formation of AgNPs stabilized by a thick ulvan shell was assessed by UV-vis, XRD, TEM, DLS and zeta potential analyses. The developed Ulvan based AgNps showed an IC50 in the range of 10 μg/ml in Balb/3T3 mouse embryo fibroblasts and antimicrobial activity toward both Gram+and Gram − bacteria.
Two novel photoactive Pt(iv)-prodrugs, based on the π-conjugated ligand 4′-phenyl-2,2′:6′,2′′-terpyridine give rise to Pt(ii) complexes with cytotoxic activity, after photoreduction.
A series of 16 novel diiron complexes of general formula [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(R′)C(R″)CN(R)(Y)}]CF3SO3 (2–7), bearing different substituents on the bridging vinyliminium ligand, was synthesized in 69–95% yields from the reactions of diiron μ-aminocarbyne precursors with various alkynes. The products were characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy; moreover the X-ray structures of 2c (R = Y = CH2Ph, R′ = R″ = Me) and 3a (R = CH2CH=CH2, Y = R′ = Me, R″ = H) were ascertained by single-crystal X-ray diffraction studies. NMR and UV–Vis methods were used to assess the D2O solubility, the stability in aqueous solution at 37 °C and the octanol–water partition coefficients of the complexes. A screening study evidenced a potent cytotoxicity of 2–7 against the A2780 cancer cell line, with a remarkable selectivity compared to the nontumoral Balb/3T3 cell line; complex 4c (R = Cy, Y = R′ = R″ = Me) revealed as the most performant of the series. The antiproliferative activity of a selection of complexes was also assessed on the cisplatin-resistant A2780cisR cancer cell line, and these complexes were capable of inducing a significant ROS production. Moreover, ESI-MS experiments indicated the absence of interaction of selected complexes with cytochrome c and the potentiality to inhibit the thioredoxin reductase enzyme (TrxR).
Regio-and stereo-selective nucleophilic attack of cyanide (from NBu 4 CN) to cationic diironaffords nitrile-aminoallylidene derivatives, 2a-f, in good to excellent yield. The analogous reaction of [1g]CF 3 SO 3 , comprising two different N-substituents, gives 4 (63%) as a mixture of two stereoisomers.The new products [1g]CF 3 SO 3 , 2a-f and 4 were characterized by IR and NMR spectroscopy, and in a number of cases by IR-spectroelectrochemistry and single crystal X-ray diffraction. The allylidene complexes are air-stable and robust in aqueous solution, however, in general they undergo oxidation within a biologically relevant range of potentials. DFT calculations were carried out to rationalize the observed stereo-selectivity of the synthesis reaction and other structural and thermodynamic aspects.The cytotoxicity of 2a-f was assessed on cisplatin sensitive and resistant human ovarian carcinoma (A2780 and A2780cisR) cell lines, and human embryonic kidney (HEK-293) cells. Experiments reveal that treatment with the compounds leads to ROS production, with an absence of direct interactions with double stranded DNA (calf thymus) and bovine serum albumin.
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