High Antiproliferative Activity of Hydroxythiopyridones over Hydroxypyridones and Their Organoruthenium Complexes

Anticancer properties of complexes derived from bidentate ligands

Cancer is the abnormal division and multiplication of cells in an organ or tissue. It is the second leading cause of death globally. There are various types of cancer such as prostate, breast, colon, lung, stomach, liver, skin, and many others depending on the tissue or organ where the abnormal growth originates. Despite the huge investment in the development of anticancer agents, the transition of research to medications that improve substantially the treatment of cancer is less than 10%. Cisplatin and its analogs are ubiquitous metal-based anticancer agents notable for the treatment of various cancerous cells and tumors but unfortunately accompanied by large toxicities due to low selectivity between cancerous and normal cells. The improved toxicity profile of cisplatin analogs bearing bidentate ligands has motivated the synthesis of vast metal complexes of bidentate ligands. Complexes derived from bidentate ligands such as β-diketones, diolefins, benzimidazoles and dithiocarbamates have been reported to possess 20 to 15,600-fold better anticancer activity, when tested on cell lines, than some known antitumor drugs currently on the market, e.g. cisplatin, oxaliplatin, carboplatin, doxorubicin, and 5-fluorouracil. This work discusses the anticancer properties of various metal complexes derived from bidentate ligands, for possible application in chemotherapy. The results discussed were evaluated by the IC50 values as obtained from cell line tests on various metal-bidentate complexes. The structure-activity relationship study of the complexes discussed, revealed that hydrophobicity is a key factor that influences anticancer properties of molecules.

Hydroxypyrone derivatives in drug discovery: from chelation therapy to rational design of metalloenzyme inhibitors

The versatile structural motif of hydroxypyrone is found in natural products and can be easily converted into hydroxypyridone and hydroxythiopyridone analogues. The favourable toxicity profile and ease of functionalization to access a vast library of compounds make them an ideal structural scaffold for drug design and discovery. This versatile scaffold possesses excellent metal chelating properties that can be exploited for chelation therapy in clinics. Deferiprone [1,2-dimethyl-3-hydroxy-4(1H)-one] was the first orally active chelator to treat iron overload in thalassemia major. Metal complexes of hydroxy-(thio)pyr(id)ones have been investigated as magnetic resonance imaging contrast agents, and anticancer and antidiabetic agents. In recent years, this compound class has demonstrated potential in discovering and developing metalloenzyme inhibitors. This review article summarizes recent literature on hydroxy-(thio)pyr(id)ones as inhibitors for metalloenzymes such as histone deacetylases, tyrosinase and metallo-β-lactamase. Different approaches to the design of hydroxy-(thio)pyr(id)ones and their biological properties against selected metalloenzymes are discussed.

Ru(ii)arene(N^N bpy/phen)-based RAPTA complexes for in vitro anti-tumour activity in human glioblastoma cancer cell lines and in vivo toxicity studies in a zebrafish model

Herein, we have introduced a series of half-sandwich Ru(ii)arene(N^N bpy/phen)-based RAPTA complexes for brain cancer therapy. Among all the synthesized complexes, [(η⁶-p-cymene)Ru^II(κ²-N,N-4,7dimethyl phenanthroline)(PTA)]·2PF₆ (4c) and [(η⁶-p-cymene)Ru^II(κ²-N,N-4,7diphenyl phenanthroline)(PTA)]·2PF₆ (4d) showed outstanding potency against the T98G, LN229 and U87MG cancer cells. The antiproliferative activity of these complexes was reinforced by neurosphere, DNA intercalation, agarose gel electrophoresis, cell cycle analysis and time-dependent ROS detection assays. The real-time reverse transcription (RT)-polymerase chain reaction (PCR) study showed that complex 4c inhibited the TNF-α-induced NF-κB phosphorylation in glioma cells. Moreover, the in vivo biodistribution of complex 4c in different organs and the morphological patterns of widely used zebrafish embryos due to toxic effects have been evaluated.

A series of half-sandwich Ru(ii)arene(N^N bpy/phen)-based RAPTA complexes have been developed for brain cancer therapy.

Theranostic Potentials of Gold Nanomaterials in Hematological Malignancies

Simple Summary

Hematological malignancies (HMs) cover 50% of all malignancies, and people of all ages can be affected by these deadly diseases. In many cases, conventional diagnostic tools fail to diagnose HMs at an early stage, due to heterogeneity and the long-term indolent phase of HMs. Therefore, many patients start their treatment at the late stage of HMs and have poor survival. Gold nanomaterials (GNMs) have shown promise as a cancer theranostic agent. GNMs are 1 nm to 100 nm materials having magnetic resonance and surface-plasmon-resonance properties. GNMs conjugated with antibodies, nucleic acids, peptides, photosensitizers, chemotherapeutic drugs, synthetic-drug candidates, bioactive compounds, and other theranostic biomolecules may enhance the efficacy and efficiency of both traditional and advanced theranostic approaches to combat HMs.

Abstract

Hematological malignancies (HMs) are a heterogeneous group of blood neoplasia generally characterized by abnormal blood-cell production. Detection of HMs-specific molecular biomarkers (e.g., surface antigens, nucleic acid, and proteomic biomarkers) is crucial in determining clinical states and monitoring disease progression. Early diagnosis of HMs, followed by an effective treatment, can remarkably extend overall survival of patients. However, traditional and advanced HMs’ diagnostic strategies still lack selectivity and sensitivity. More importantly, commercially available chemotherapeutic drugs are losing their efficacy due to adverse effects, and many patients develop resistance against these drugs. To overcome these limitations, the development of novel potent and reliable theranostic agents is urgently needed to diagnose and combat HMs at an early stage. Recently, gold nanomaterials (GNMs) have shown promise in the diagnosis and treatment of HMs. Magnetic resonance and the surface-plasmon-resonance properties of GNMs have made them a suitable candidate in the diagnosis of HMs via magnetic-resonance imaging and colorimetric or electrochemical sensing of cancer-specific biomarkers. Furthermore, GNMs-based photodynamic therapy, photothermal therapy, radiation therapy, and targeted drug delivery enhanced the selectivity and efficacy of anticancer drugs or drug candidates. Therefore, surface-tuned GNMs could be used as sensitive, reliable, and accurate early HMs, metastatic HMs, and MRD-detection tools, as well as selective, potent anticancer agents. However, GNMs may induce endothelial leakage to exacerbate cancer metastasis. Studies using clinical patient samples, patient-derived HMs models, or healthy-animal models could give a precise idea about their theranostic potential as well as biocompatibility. The present review will investigate the theranostic potential of vectorized GNMs in HMs and future challenges before clinical theranostic applications in HMs.

Key considerations when using the sulforhodamine B assay for screening novel anticancer agents

Anticancer drug discovery programmes use a large number of in-vitro assays to screen the potency of compound libraries. The accuracy and reliability of these in-vitro assays are vital in selecting potent lead candidates for further (pre)clinical studies. Among the commonly used cell viability assays, the sulforhodamine B (SRB) assay has been a popular choice due to its simplicity, accuracy, reliability and reproducibility. SRB dye interacts with protein's basic amino acids and viable cell number is determined based on the cellular protein content. In this study, the cytotoxic potency of the novel hydroxythiopyridone derivatives towards A549 and H522 cells was determined using the SRB assay. The known drugs oxaliplatin and vorinostat were also examined. The resulting EC50 values were accurate, reliable and reproducible. However, all EC50 values calculated in 6-well plates were higher compared to those determined from 96-well plates. Furthermore, results from 6-well plates were also more variable compared to 96-well plates. Our results confirm that SRB assay is a reliable technique in screening the potency of anticancer drug candidates but plating conditions need to be carefully considered.

Synthesis, characterisation and biological activity of the ruthenium(II) complexes of the N4-tetradentate (N4-TL), 1,6-di(2'-pyridyl)-2,5-dibenzyl-2,5-diazahexane (picenBz2)

A series of complexes of the type rac-cis-β-[Ru(N₄-T_L)(N₂-bidentates)]²⁺ (where N₄-T_L = 1,6-di(2'-pyridyl)-2,5-dibenzyl-2,5-diazahexane (picenBz₂, N₄-T_L-2) and N₂-bidentates = 1,10-phenanthroline (phen, Ru-2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, Ru-3), 7,8-dimethyl-dipyrido[3,2-a:2',3'-c] phenazine (dppzMe_2,Ru-4), 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline (phenpyrBz, Ru-5), 2-(p-tolyl)-1H-imidazo[4,5-f][1,10]phenanthroline (phenpyrBzMe, Ru-6), 2-(4-nitrophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (phenpyrBzNO_2,Ru-7), were synthesised and characterised and X-ray crystallography of Ru-5 obtained. The in vitro cytotoxicity assays revealed that Ru-6 was 5, 2 and 19-fold more potent than oxaliplatin, cisplatin, and carboplatin, respectively displaying an average GI₅₀ value of ≈ 0.76 μM against a panel of 11 cancer cell lines.

Ruthenium Complexes: An Alternative to Platinum Drugs in Colorectal Cancer Treatment

Colorectal cancer (CRC) is one of the intimidating causes of death around the world. CRC originated from mutations of tumor suppressor genes, proto-oncogenes and DNA repair genes. Though platinum (Pt)-based anticancer drugs have been widely used in the treatment of cancer, their toxicity and CRC cells' resistance to Pt drugs has piqued interest in the search for alternative metal-based drugs. Ruthenium (Ru)-based compounds displayed promising anticancer activity due to their unique chemical properties. Ru-complexes are reported to exert their anticancer activities in CRC cells by regulating different cell signaling pathways that are either directly or indirectly associated with cell growth, division, proliferation, and migration. Additionally, some Ru-based drug candidates showed higher potency compared to commercially available Pt-based anticancer drugs in CRC cell line models. Meanwhile Ru nanoparticles coupled with photosensitizers or anticancer agents have also shown theranostic potential towards CRC. Ru-nanoformulations improve drug efficacy, targeted drug delivery, immune activation, and biocompatibility, and therefore may be capable of overcoming some of the existing chemotherapeutic limitations. Among the potential Ru-based compounds, only Ru (III)-based drug NKP-1339 has undergone phase-Ib clinical trials in CRC treatment.