BSA-binding properties and anti-proliferative effects of amino acids functionalized polyoxomolybdates

Polyoxometalates Impact as Anticancer Agents

Polyoxometalates (POMs) are oxoanions of transition metal ions, such as V, Mo, W, Nb, and Pd, forming a variety of structures with a wide range of applications. Herein, we analyzed recent studies on the effects of polyoxometalates as anticancer agents, particularly their effects on the cell cycle. To this end, a literature search was carried out between March and June 2022, using the keywords "polyoxometalates" and "cell cycle". The effects of POMs on selected cell lines can be diverse, such as their effects in the cell cycle, protein expression, mitochondrial effects, reactive oxygen species (ROS) production, cell death and cell viability. The present study focused on cell viability and cell cycle arrest. Cell viability was analyzed by dividing the POMs into sections according to the constituent compound, namely polyoxovanadates (POVs), polyoxomolybdates (POMos), polyoxopaladates (POPds) and polyoxotungstates (POTs). When comparing and sorting the IC₅₀ values in ascending order, we obtained first POVs, then POTs, POPds and, finally, POMos. When comparing clinically approved drugs and POMs, better results of POMs in relation to drugs were observed in many cases, since the dose required to have an inhibitory concentration of 50% is 2 to 200 times less, depending on the POMs, highlighting that these compounds could become in the future an alternative to existing drugs in cancer therapy.

Promising application of polyoxometalates in the treatment of cancer, infectious diseases and Alzheimer's disease

As shown in studies conducted in recent decades, polyoxometalates (POMs), as inorganic metal oxides, have promising biological activities, including antitumor, anti-infectious and anti-Alzheimer’s activities, due to their special structures and properties. However, some side effects impede their clinical applications to a certain extent. Compared with unmodified POMs, POM-based inorganic–organic hybrids and POM-based nanocomposite structures show significantly enhanced bioactivity and reduced side effects. In this review, we introduce the biological activities of POMs and their derivatives and highlight the side effects of POMs on normal cells and organisms and their possible mechanisms of action. We then propose a development direction for overcoming their side effects. POMs are expected to constitute a new generation of inorganic metal drugs for the treatment of cancer, infectious diseases, and Alzheimer's disease.

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Niobium polyoxometalate–folic acid conjugate as a hybrid drug for cancer therapeutics

In this work, covalently bonded folic acid to niobium substituted Wells-Dawson polyoxometalate, (Bu4N)5H4[P2W15Nb3O62]-folic acid, has been synthesized and characterized. Afterward, the bioactivity behavior of this hybrid compound against cervical (HeLa)...

A GdW10@PDA-CAT Sensitizer with High-Z Effect and Self-Supplied Oxygen for Hypoxic-Tumor Radiotherapy

Anticancer treatment is largely affected by the hypoxic tumor microenvironment (TME), which causes the resistance of the tumor to radiotherapy. Combining radiosensitizer compounds and O2 self-enriched moieties is an emerging strategy in hypoxic-tumor treatments. Herein, we engineered GdW10@PDA-CAT (K3Na4H2GdW10O36·2H2O, GdW10, polydopamine, PDA, catalase, CAT) composites as a radiosensitizer for the TME-manipulated enhancement of radiotherapy. In the composites, Gd (Z = 64) and W (Z = 74), as the high Z elements, make X-ray gather in tumor cells, thereby enhancing DNA damage induced by radiation. CAT can convert H2O2 to O2 and H2O to enhance the X-ray effect under hypoxic TME. CAT and PDA modification enhances the biocompatibility of the composites. Our results showed that GdW10@PDA-CAT composites increased the efficiency of radiotherapy in HT29 cells in culture. This polyoxometalates and O2 self-supplement composites provide a promising radiosensitizer for the radiotherapy field.

Nanolipid-loaded Preyssler polyoxometalate: Synthesis, characterization and invitro inhibitory effects on HepG2 tumor cells

Polyoxometalate-based drugs have been selected by some researchers as alternative antitumor substances with promising results in suppression of tumor growth because of low toxicity towards the human body and high activity. In this research, for the first time, nanolipid-loaded Preyssler polyoxometalate with diameters of 230-250 nm was synthesized and characterized by the Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), Atomic Force Microscopy (AFM), and Infrared (IR) spectroscopy. The nanoliposomes were found to be nearly spherical, without any agglomeration with the Entrapment Efficiency of 53.8%. In -vitro antitumor activity of the synthesized nanoliposomes was investigated using the MTT method on HepG2 tumor cells. Our findings showed enhanced anticancer activity for the nanolipid-loaded Preyssler (NLP) compared to the Sorafenib as a commercially drug at 72 h. Selectivity of the synthesized NLP and Sorafenib for cancer cells versus primary HFF cells was obtained as 4.2 and 2.2, respectively. The IC50 value of the loaded nanoliposomes for cancer cells and normal cells was equal to 470 and 2000 μg/mL, respectively at 72 h, which was much better compared to that of the Sorafenib (7 and 16 μg/mL, respectively).

Polyoxometalates in Biomedicine: Update and Overview

BACKGROUND

Polyoxometalates (POMs) are negatively charged metal-oxo clusters of early transition metal ions in high oxidation states (e.g., WVI, MoVI, VV). POMs are of interest in the fields of catalysis, electronics, magnetic materials and nanotechnology. Moreover, POMs were shown to exhibit biological activities in vitro and in vivo, such as antitumor, antimicrobial, and antidiabetic.

METHODS

The literature search for this peer-reviewed article was performed using PubMed and Scopus databases with the help of appropriate keywords.

RESULTS

This review gives a comprehensive overview of recent studies regarding biological activities of polyoxometalates, and their biomedical applications as promising anti-viral, anti-bacterial, anti-tumor, and anti-diabetic agents. Additionally, their putative mechanisms of action and molecular targets are particularly considered.

CONCLUSION

Although a wide range of biological activities of Polyoxometalates (POMs) has been reported, they are to the best of our knowledge not close to a clinical trial or a final application in the treatment of diabetes or infectious and malignant diseases. Accordingly, further studies should be directed towards determining the mechanism of POM biological actions, which would enable fine-tuning at the molecular level, and consequently efficient action towards biological targets and as low toxicity as possible. Furthermore, biomedical studies should be performed on solutionstable POMs employing physiological conditions and concentrations.

Polyoxometalates as Potential Next-Generation Metallodrugs in the Combat Against Cancer

Polyoxometalates (POMs) are an emerging class of inorganic metal oxides, which over the last decades demonstrated promising biological activities by the virtue of their great diversity in structures and properties. They possess high potential for the inhibition of various tumor types; however, their unspecific interactions with biomolecules and toxicity impede their clinical usage. The current focus of the field of biologically active POMs lies on organically functionalized and POM-based nanocomposite structures as these hybrids show enhanced anticancer activity and significantly reduced toxicity towards normal cells in comparison to unmodified POMs. Although the antitumor activity of POMs is well documented, their mechanisms of action are still not well understood. In this Review, an overview is given of the cytotoxic effects of POMs with a special focus on POM-based hybrid and nanocomposite structures. Furthermore, we aim to provide proposed mode of actions and to identify molecular targets. POMs are expected to develop into the next generation of anticancer drugs that selectively target cancer cells while sparing healthy cells.

Synthesis, cytotoxicity and antitumour mechanism investigations of polyoxometalate doped silica nanospheres on breast cancer MCF-7 cells

Polyoxometalates (POMs) have shown the potential anti-bacterial, anti-viral and anti-tumor activities. In order to improve their physiological stability and antitumour activity for medical application, K2Na[AsIIIMo6O21(O2CCH2NH3)3]·6H2O doped silica nanospheres (POM@SiO2) with diameters of ~40 nm have been synthesized by the water-in-oil microemulsion method in this study. The obtained spheres were morphologically uniform nanosized and nearly monodispersed in solution. The nanoparticles had high entrapment efficiency, which was upto 46.2% by the inductively coupled plasma mass spectrometry (ICP-MS) analysis and POMs slowly released from the nanospheres both in the PH 7.4 and 5.5 phosphate buffer saline (PBS) solutions in 60 h. The in vitro MTT assays of particles on MCF-7 cell line (a human breast adenocarcinoma cell line) exhibited enhanced antitumor activity compared to that of plain polyoxometalate. The IC50 value of the POM@SiO2 nanoparticles was 40.0 μg/mL at 24 h calculated by the encapsulated POM concentration, which was much lower comparing to that of 2.0 × 104 μg/mL according to the pure POM. And the SiO2 shells showed low inhibitory effect at the corresponding concentration. Confocal images further indicated the cell morphology changes and necrosis. Flow cytometric analysis showed nanoparticles induced the apoptosis by arresting the cells in S phase and western blot analysis indicated they promoted apoptosis by inhibiting the Bcl-2 protein. Moreover, the study of interactions between human serum albumin (HSA) and the nanoparticles indicated the fluorescence quenching was static, and the nanoparticles were likely to bind to HSA and changed its conformation.

Antileukemic activity of an arsenomolybdate in the human HL-60 and U937 leukemia cells

The antileukemic activity, mechanisms and serum albumin interactions of an arsenomolybdate, K₂Na[AsMo₆O₂₁(O₂CCH₂NH₃)₃]·6H₂O (1), was evaluated in the human leukemia HL-60 and U937 cells. The results indicated that 1 could inhibit the proliferation of both leukemia cell lines in a dose-dependent manner with the 50% lethal concentration (IC₅₀) value of 8.61μM for HL-60 and 14.50μM for U937 at 24h, compare to the positive controls, all-trans retinoic acid (ATRA) with IC₅₀ value of 20.76μM and 14.85μM,and As₂O₃ with IC₅₀ value of 6.40μM and 8.75μM at 24h, respectively (P<0.05). Furthermore, the anti-leukemia activity of compound 1 might be medicated by arresting the leukemic cells in the G₁ phase and inducing apoptosis via caspase-3 and bcl-2 regulatory proteins. Spectroscopic techniques results showed that the fluorescence of human serum albumin was quenched by compound 1, and the quenching mechanism was mainly static quenching. Compound 1 might be a potential medicinal candidate against acute promyelocytic leukemia.