Ru, Rh and Ir metal complexes of pyridyl chalcone derivatives: Their potent antibacterial activity, comparable cytotoxicity potency and selectivity to cisplatin

Facile Method to Obtain Functionalised η6-Bound Arenes in Ru(II) and Os(II) Half-Sandwich Complexes

Half-sandwich Ru(II)- and Os(II)-arene complexes have great potential for catalytic and biological applications. The possibility of fine-tuning their chemical reactivity by including modifications in the ligands around the metal adds to their many advantages. However, structural modifications at the η6-bound arene have had significant synthetic limitations, particularly in the design of Os(II)-tethered complexes. For the first time, we have employed a practical C(sp3)-C(sp2) coupling to obtain 28 new Ru(II) and Os(II) η6-arene half-sandwich complexes with a wide variety of arene functionalities, including those that enable the formation of tether rings, such as quinoline, and coumarin. The introduction of novel functional groups at the arene in Ru(II)- and Os(II) half-sandwich complexes can broaden the synthetic scope of this type of organometallic complexes, and help to take full advantage of their structural diversity, for example, in intracellular catalysis.

Dinuclear copper(II) complexes with a bridging bis(chalcone) ligand reveal considerable in vitro cytotoxicity on human cancer cells and enhanced selectivity

A bis(chalcone) molecule (H2L) was synthesized via Aldol's condensation from terephthalaldehyde and 2'-hydroxyacetophenone and it was used as bridging ligand for the preparation of five dinuclear copper(II) complexes of the composition [Cu(NN)(μ-L)Cu(NN)](NO3)2⋅nH2O (n = 0-2) (1-5), where NN stands for a bidentate N-donor ligand such as phen (1,10-phenanthroline, 1), bpy (2,2'-bipyridine, 2), mebpy (5,5'-dimethyl-2,2'-dipyridine, 3), bphen (bathophenanthroline, 4) and nphen (5-nitro-1,10-phenanthroline, 5). The compounds were characterized by different suitable techniques to confirm their purity, composition, and structure. Moreover, the products were evaluated for their in vitro cytotoxicity on a panel of human cancer cell lines: ovarian (A2780), ovarian resistant to cisplatin (A2780R), prostate (PC3), osteosarcoma (HOS), breast (MCF7) and lung (A549), and normal fibroblasts (MRC-5), showing significant cytotoxicity in most cases, with IC50 ≈ 0.35-7.8 μM. Additionally, the time-dependent cytotoxicity and cellular uptake of copper, together with flow cytometric studies concerning cell-cycle arrest, induction of cell death and autophagy and induction of intracellular ROS/superoxide production in A2780 cells, were also performed. The results of biological testing on A2780 cells pointed out a possible mechanism of action characterized by the G2/M cell cycle arrest and induction of apoptosis by triggering the intrinsic signalling pathway associated with the damage of mitochondrial structure and depletion of mitochondrial membrane potential. SYNOPSIS: Dinuclear Cu(II) complexes bearing a bridging bis(chalcone) ligand revealed high in vitro cytotoxicity, initiated A2780 cell arrest at G2/M phase and efficiently triggered intrinsic pathway of apoptosis.

Flavonoid-metal ion Complexes as Potent Anticancer Metallodrugs: A Comprehensive Review

BACKGROUND

Flavonoids and their analogous are mainly found in pink lady apples, green and black tea (catechins), celery and red peppers, onions, broccoli and spinach, berries, cherries, soybean, citrus fruits, and fungi. The different derivatives of flavonoids belonging to polyphenolic compounds such as 3,4',5,7-Tetrahydroxyflavylium (pelargonidin), 2-(3,4-Dihydroxyphenyl)chromenylium-3,5,7-triol (cyanidin), 3,3',4',5,5',7-Hexahydroxyflavylium (delphinidin), 3,3',4',5,7-Pentahydroxy-5'-methoxyflavylium (petunidin), and 3,4',5,7-Tetrahydroxy-3',5'-dimethoxyflavylium (malvidin) can act as good chelating agents for metal-chelate complex formation. These flavonoid-metal complexes have been reported to have various biomedical and pharmacological activities.

OBJECTIVE

Flavonoid-metal ion complexes display a broad spectrum of biological properties such as antioxidant, anti-inflammatory, anti-allergic, antiviral, anticarcinogenic, and cytotoxic activity. The literature survey showed that flavonoid metal complexes have potential therapeutic properties against various cancerous cells. The objective is to gain insight into the current perspective and development of novel anticancer metallodrugs.

METHODS

The flavonoid-metal ion complexes can be prepared by reacting flavonoid ligand with appropriate metal salt in aqueous or alcoholic reaction medium under stirring or refluxing conditions. In this review article, the various reported methods for the synthesis of flavonoid-metal complexes have been included. The utility of synthetic methods for flavonoid-metal complexes will support the discovery of novel therapeutic drugs.

RESULTS

In this review study, short libraries of flavonoid-metal ion complexes were studied as potential anticancer agents against various human cancer cell lines. The review report reveals that metal ions such as Fe, Co, Ni, Cu, Zn, Rh, Ru, Ga, Ba, Sn etc., when binding to flavonoid ligands, enhance the anticancer activity compared to free ligands. This review study covered some important literature surveys for the last two decades.

CONCLUSION

It has been concluded that flavonoid metal complexes have been associated with a wide range of biological properties that could be noteworthy in the medicinal field. Therefore, to develop a new anticancer drug, it is essential to determine the primordial interaction of drug with DNA under physiological or anatomical conditions. The study of numerous flavonoid metal complexes mentioned in this paper could be the future treatment against various cancerous diseases.

In Vitro and In Vivo Antitumor Assay of Mitochondrially Targeted Fluorescent Half-Sandwich Iridium(III) Pyridine Complexes

Half-sandwich iridium(III) complexes show potential value in the anticancer field. However, complexes with favorable luminescence performance are rare, which limits further investigation of the anticancer mechanism. In this paper, 10 triphenylamine-modified fluorescent half-sandwich iridium(III) pyridine complexes {[(η⁵-Cp^x)Ir(L)Cl₂]} (Ir1-Ir10) were prepared and showed potential antiproliferative activity, effectively inhibiting the migration of A549 cells. Ir6, showing the best activity among these complexes, exhibited excellent fluorescence performance (absolute fluorescence quantum yield of 15.17%) in solution. Laser confocal detection showed that Ir6 followed an energy-dependent cellular uptake mechanism, specifically accumulating in mitochondria (Pearson co-localization coefficient of 0.95). A Western blot assay further confirmed the existence of a mitochondrial apoptotic channel. Additionally, Ir6 could arrest the cell cycle at the G₂/M phase, catalyze NADH oxidation, reduce the mitochondrial membrane potential, induce an increase in the level of intracellular reactive oxygen species, and exhibit a mechanism of oxidation. An in vivo antitumor assay confirmed that Ir6 can effectively inhibit tumor growth and is safer than cisplatin.

Heteroleptic Copper(II) Complexes Containing 2'-Hydroxy-4-(Dimethylamino)Chalcone Show Strong Antiproliferative Activity

A series of six heteroleptic copper(II) complexes with 2'-hydroxy-4-(dimethylamino)chalcone (HL) with the composition [Cu(N-N)(L)]NO₃ (1-6), where N-N stands for dmbpy = 5,5'-dimethyl-2,2'-bipyridine (1), bphen = 4,7-diphenyl-1,10-phenanthroline (2), dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine (3), nphen = 5-nitro-1,10-phenanthroline (4), bpy = 2,2'-bipyridine, (5), and dpa = 2,2'-dipyridylamine (6), was prepared and thoroughly characterized. The in vitro cytotoxicity screening on eight human cancer cell lines identified complex 2, containing the bulkiest N-donor ligands (bphen) as highly cytotoxic against cancer cells, with IC₅₀ values ranking from 1.0 to 2.3 μM, with good selectivity and low toxicity against healthy human fetal lung fibroblasts MRC-5. The cell-based assays, involving the most effective complex 2 in A2780 cancer cells, revealed its strong pro-apoptotic effects based on the effective activation of caspases 3/7, ROS overproduction, and autophagy in the A2780 cells while not impeding the cell cycle and mitochondrial membrane functions. The cellular uptake studies in A2780 and 22Rv1 cells uncovered no intracellular transport of the cationic complex 2, supporting the hypothesis that the in vitro anticancer effects of complex 2 are based on the combined extrinsic activation of apoptosis and autophagy induction.

Chalcone: A Promising Bioactive Scaffold in Medicinal Chemistry

Chalcones are a class of privileged scaffolds with high medicinal significance due to the presence of an α,β-unsaturated ketone functionality. Numerous functional modifications of chalcones have been reported, along with their pharmacological behavior. The present review aims to summarize the structures from natural sources, synthesis methods, biological characteristics against infectious and non-infectious diseases, and uses of chalcones over the past decade, and their structure–activity relationship studies are detailed in depth. This critical review provides guidelines for the future design and synthesis of various chalcones. In addition, this could be highly supportive for medicinal chemists to develop more promising candidates for various infectious and non-infectious diseases.

Design, Synthesis, and Antifungal Activity of Novel Chalcone Derivatives Containing a Piperazine Fragment

In an attempt to find the biorational pesticides, 20 novel chalcone derivatives containing a piperazine fragment were designed and synthesized. Their fungicidal activities and preliminarily action mechanism against Rhizoctonia solani were evaluated. Strikingly, the biological activity of compound D2 was obtained by optimizing the structure of the system. Subsequently, the practical value of compound D2 was ascertained by the relative surveys on in vivo anti-R. solani and anti-Colletotrichum gloeosporioides. The results revealed by scanning electron microscopy demonstrated that compound D2 could induce irregular and shrivelled growth of mycelium and rupture of the mycelium surface. This study indicates that chalcone derivatives containing a piperazine skeleton had better inhibitory effect on plant fungi, providing further complementary research on new pesticides.

Influence of counterions on the formation of supramolecular platinum group metal complexes containing pyridyl thioamide derivatives: antioxidant and antimicrobial studies

A series of half-sandwich metal thioamide derivative complexes exhibiting interesting coordination modes in the presence of counterions.

Mass Spectrometric Investigation of Organo-Functionalized Magnetic Nanoparticles Binding Properties toward Chalcones

Chalcones are naturally occurring compounds exhibiting multiple biological functions related to their structure. The investigation of complexes formed by chalcones, namely 2',4'-dihydroxy-2-methoxychalcone (DH-2-MC) and 2',4'-dihydroxy-3-methoxychalcone (DH-3-MC), with organo-functionalized Fe3O4 magnetic nanoparticles using mass spectrometric techniques is reported. The magnetic nanoparticles were obtained by the silanization of Fe3O4 particles with 3-aminopropyltrimethosysilane, which were subsequently reacted with 3-hydroxybenzaldehyde (3-HBA) or 2-pyridinecarboxaldehyde (2-PCA), resulting in the formation of Schiff base derivatives. The formation of their complexes with chalcones was studied using electrospray (ESI) and flowing atmosphere-pressure afterglow (FAPA) mass spectrometric (MS) ionization techniques. The functional nanoparticles which were synthesized using 3-hydroxybenzaldehyde displayed higher affinity towards examined chalcones than their counterparts obtained using 2-pyridinecarboxaldehyde, which has been proved by both ESI and FAPA techniques. For the examined chalcones, two calibration curves were obtained using the ESI-MS method, which allowed for the quantitative analysis of the performed adsorption processes. The presence of Cu(II) ions in the system significantly hindered the formation of material-chalcone complexes, which was proved by the ESI and FAPA techniques. These results indicate that both mass spectrometric techniques used in our study possess a large potential for the investigation of the binding properties of various functional nanoparticles.

Anticancer Half-Sandwich Rhodium(III) Complexes

Platinum-based anticancer drugs are most likely the most successful group of bioinorganic compounds. Their apparent disadvantages have led to the development of anticancer compounds of other noble metals, resulting in several ruthenium-based drugs which have entered clinical trials on oncological patients. Besides ruthenium, numerous rhodium complexes have been recently reported as highly potent antiproliferative agents against various human cancer cells, making them potential alternatives to Pt- and Ru-based metallodrugs. In this review, half-sandwich Rh(III) complexes are overviewed. Many representatives show higher in vitro potency than and different mechanisms of action (MoA) from the conventional anticancer metallodrugs (cisplatin in most cases) or clinically studied Ru drug candidates. Furthermore, some of the reviewed Rh(III) arenyl complexes are also anticancer in vivo. Pioneer anticancer organorhodium compounds as well as the recent advances in the field are discussed properly, and adequate attention is paid to their anticancer activity, solution behaviour and various processes connected with their MoA. In summary, this work summarizes the types of compounds and the most important biological results obtained in the field of anticancer half-sandwich Rh complexes.