Reactivity of potential anti-diabetic molybdenum(VI) complexes in biological media: A XANES spectroscopic study

Synthesis of an amantadine-based novel Schiff base and its transition metal complexes as potential ALP, α-amylase, and α-glucosidase inhibitors

A Schiff base ligand HL, (E)-2-((adamantan-1-ylimino)methyl)-6-allylphenol, was synthesized by condensation of amantadine with 3-allyl-2-hydroxybenzaldehyde, followed by the synthesis of its Zn(ii), Co(ii), Cr(iii), and VO(iv) complexes under reflux conditions. The synthesized compounds were comprehensively elucidated by using different spectroscopic and analytical techniques: UV-Vis, ¹H and ¹³C-NMR, FT-IR, ESI-MS, thermal, and single-crystal XRD analysis. The chemical composition of the synthesized compounds was also verified by molar conductance and elemental analysis. An octahedral geometry for Cr(iii) and Co(ii) complexes, tetrahedral for Zn(ii) complex, and square pyramidal geometry have been proposed for VO(iv) complexes. The antidiabetic activities of the synthesized compounds were also evaluated by performing in vitro α-amylase and α-glucosidase inhibition studies. The Co(ii) complex exhibited the highest α-glucosidase inhibitory activity, whereas oxovanadium(iv) and zinc(ii) complexes were also found to be effective against α-amylase. In alkaline phosphatase (ALP) inhibition studies, the HL was found to be inactive, while the complexes showed remarkable enzyme inhibition in the following order: VO > Zn > Co, in a concentration-dependent manner.

The effect of exposure to MoO3-NP and common bean fertilized by MoO3-NPs on biochemical, hematological, and histopathological parameters in rats

Nanotechnologies has been used to introduce several beneficial tools in the agricultural field. Herein, the effect of molybdenum oxide nanoparticles (MoO₃-NPs) was investigated by evaluating the hematological, biochemical, and histopathological parameters in rats orally exposed to MoO₃-NPs or fed common beans (CB) fertilized by MoO₃-NPs. In the first study, 18 rats were randomly divided into 3 groups: G1 (control group) was given water orally, while G2 and G3 were administered 10 and 40 ppm MoO₃-NPs by oral gavage tube, respectively. There was a significant increase in the levels of alanine aminotransferase (ALT), albumin, and total protein; however, there was a a significant decrease in body weight change (BWC), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine, creatine kinase–MB (CK-MB), thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and testosterone levels in G3 compared to G1. In the second study, 24 rats were divided into 4 groups: the control (C) group was fed a balanced diet, and three groups were fed on a balanced diet plus 10% CB that was fertilized with 0, 10, and 40 ppm MoO₃-NPs, resulting in nCB, CB10, and CB40 groups, respectively. This revealed a significant increase in BWC and total food intake (TFI) but a significant decrease in relative kidney weight in all the CB groups compared to the control group. In CB10 and CB40 groups ALT, LDH, TSH, FT3, and testosterone levels were significantly lower than the respective levels in the control group. We concluded that high doses of MoO₃-NPs caused more side effects than low doses in both experiments.

Healing Diabetic Ulcers with MoO3-X Nanodots Possessing Intrinsic ROS-Scavenging and Bacteria-Killing Capacities

Diabetic ulcers (DUs) appearing as chronic wounds are difficult to heal due to the oxidative stress in the wound microenvironment and their high susceptibility to bacterial infection. A routine treatment combining surgical debridement with anti-infection therapy is widely used for treating DUs in the clinic, but hardly offers a satisfying wound healing outcome. It is known that a long-term antibiotic treatment may also lead to the drug resistance of pathogens. To address these challenges, new strategies combining both reactive oxygen species (ROS) scavenging and bacterial sterilization have been proposed for fighting against DUs. Following this idea, oxygen deficient molybdenum-based nanodots (MoO_3-X ) for healing the DUs are reported. The ROS scavenging ability of MoO_3-X nanodots is investigated and the antibacterial property of the nanodots is also demonstrated. The systematic cell and animal experimental results indicate that the MoO_3-X nanodots can effectively reduce inflammation, promote epithelial cell regeneration, accelerate angiogenesis, and facilitate DUs recovery. Most importantly, they present excellent capacity to diminish infection of methicillin-resistant Staphylococcus aureus, manifesting the potent application prospect of MoO_3-X nanodots for diabetic wound therapy.

Near-Infrared Regulated Nanozymatic/Photothermal/Photodynamic Triple-Therapy for Combating Multidrug-Resistant Bacterial Infections via Oxygen-Vacancy Molybdenum Trioxide Nanodots

Bacterial infections have become a major danger to public health because of the appearance of the antibiotic resistance. The synergistic combination of multiple therapies should be more effective compared with the respective one alone, but has been rarely demonstrated in combating bacterial infections till now. Herein, oxygen-vacancy molybdenum trioxide nanodots (MoO_3-x NDs) are proposed as an efficient and safe bacteriostatic. The MoO_3-x NDs alone possess triple-therapy synergistic efficiency based on the single near-infrared irradiation (808 nm) regulated combination of photodynamic, photothermal, and peroxidase-like enzymatic activities. Therein, photodynamic and photothermal therapies can be both achieved under the excitation of a single wavelength light source (808 nm). Both the photodynamic and nanozyme activity can result in the generation of reactive oxygen species (ROS) to reach the broad-spectrum sterilization. Interestingly, the photothermal effect can regulate the MoO_3-x NDs to their optimum enzymatic temperature (50 °C) to give sufficient ROS generation in low concentration of H₂ O₂ (100 µm). The MoO_3-x NDs show excellent antibacterial efficiency against drug-resistance extended spectrum β-lactamases producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Animal experiments further indicate that the MoO_3-x NDs can effectively treat wounds infected with MRSA in living systems.

Steering Efficacy of Nano Molybdenum Towards Cancer: Mechanism of Action

Conventional cancer therapies possess a plethora of limitations which led to the awakening of nanotechnology and nanomedicine. However, technological success is widely dependent on complete understanding of the complexity and heterogeneity of tumor biology on one hand and nanobiointeractions associated with challenges of synthesis, translation, and commercialization on the other. The present study therefore deals with one such targeted approach aiming at synthesizing, characterizing, and understanding the efficacy of molybdenum oxide nanoparticles. The phase structure, morphology, and elemental composition of the synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The cytotoxicity studies revealed that the IC50 vales of molybdenum trioxide (MoO3) particles against skin cancer cells (melanoma and non-melanoma) were around 200-300 μg. The nanoparticles were found to induce mitochondrial-mediated apoptosis driven by the apoptotic genes such as BAX and Bcl2. Molybdenum being a cofactor for the majority of metabolic enzymes could have triggered the selective internalization of the nanoparticles which in turn could have modified the granularity of the cytoplasm and subsequently lead to mitochondrial-mediated apoptosis. Further, the anti-angiogenic property of MoO3 nanoparticles was corroborated using Chick chorioallantoic membrane (CAM) assay and aortic ring assay. Taken together , unraveling the role of MoO3 nanoparticles in cancer and angiogenesis opens up venues for nano biological intervention of selective cancer cell targeting with minimal damage to the normal cells using natural trace elements that are generally known to influence various metabolic enzymes.

Effect of Molybdenum Nanoparticles on Blood Cells, Liver Enzymes, and Sexual Hormones in Male Rats

Despite an increasing surge in application of nanoparticles in industries, there is a serious lack of information concerning their impact on human health and the environment. The present study investigated effects of molybdenum nanoparticles (Mo NPs) injected intraperitoneally into Sprague-Dawley rats at different doses of Mo NPs (5, 10, and 15 mg/kg BW per day) during a period of 28 days. Hematological and biochemical parameters as well as sexual hormones and histopathological examinations of the liver and testis were assessed and compared with control group. The results showed that the serum levels of testosterone decreased significantly in both groups of 10 and 15 mg (Mo NPs)/kg BW in comparison with the control group (p < 0.05). However, there were insignificant differences observed in luteinizing hormone (LH) levels and hematological parameters when compared with the control group (p > 0.05). The results of liver enzymes showed that serum levels of aspartate aminotransferase (AST) decreased significantly in both dosage groups of 5 and 10 mg/kg BW (Mo NPs) when compared with the control group (p < 0.05), and significant decrease obtained in lactate dehydrogenase (LDH) levels at dose of 5 mg/kg BW in comparison with the control group (p < 0.05). The histopathological examination of testis showed a decrease in number of Leydig cells. Also, the number of chronic inflammatory cells increased in portal triad and parenchyma in liver tissue of rats exposed to Mo NPs.

Cellulose acetate-based composites with antimicrobial properties from embedded molybdenum trioxide particles

The objective of this research was to develop novel cellulose acetate (biopolymer) composite materials with an excellent antimicrobial activity by embedding molybdenum trioxide particles with unique high specific surface area. High surface area molybdenum trioxide particles were prepared from freshly precipitated molybdenum trioxide dihydrate (MoO₃ ·2H₂ O) and subsequent calcination at 340°C under H₂ /N₂ gas. Microbiological evaluation against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed applying a roll-on test and excellent antimicrobial activities were determined for composites with embedded anhydrous molybdenum trioxide with a high specific surface area. Cellulose acetate composites comprising MoO₃ particles can eliminate three harmful bacteria as a result of the release of protons from the material and surface enlargement of the molybdenum trioxide particles. The findings support a proposed antimicrobial mechanism based on local acidity increase due to large specific surface areas.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, development of a novel thermoplastic bio-based composite with excellent antimicrobial surface properties is investigated. To the best of our knowledge, this is the first report to evaluate the antimicrobial properties of molybdenum trioxide embedded into a cellulose acetate as biopolymer matrix. The developed composites might step up to innovative applications used in modern medical and public environments.

Reactivity and Speciation of Anti-Diabetic Vanadium Complexes in Whole Blood and Its Components: The Important Role of Red Blood Cells

Reactions with blood components are crucial for controlling the antidiabetic, anticancer, and other biological activities of V(V) and V(IV) complexes. Despite extensive studies of V(V) and V(IV) reactions with the major blood proteins (albumin and transferrin), reactions with whole blood and red blood cells (RBC) have been studied rarely. A detailed speciation study of Na3[V(V)O4] (A), K4[V(IV)2O2(citr)2]·6H2O (B; citr = citrato(4-)); [V(IV)O(ma)2] (C; ma = maltolato(-)), and (NH4)[V(V)(O)2(dipic)] (D; dipic = pyridine-2,6-dicarboxylato(2-)) in whole rat blood, freshly isolated rat plasma, and commercial bovine serum using X-ray absorption near-edge structure (XANES) spectroscopy is reported. The latter two compounds are potential oral antidiabetic drugs, and the former two are likely to represent their typical decomposition products in gastrointestinal media. XANES spectral speciation was performed by principal component analysis and multiple linear regression techniques, and the distribution of V between RBC and plasma fractions was measured by electrothermal atomic absorption spectroscopy. Reactions of A, C, or D with whole blood (1.0 mM V, 1-6 h at 310 K) led to accumulation of ∼50% of total V in the RBC fraction (∼10% in the case of B), which indicated that RBC act as V carriers to peripheral organs. The spectra of V products in RBC were independent of the initial V complex, and were best fitted by a combination of V(IV)-carbohydrate (2-hydroxyacid moieties) and/or citrate (65-85%) and V(V)-protein (15-35%) models. The presence of RBC created a more reducing environment in the plasma fraction of whole blood compared with those in isolated plasma or serum, as shown by the differences in distribution of V(IV) and V(V) species in the reaction products of A-D in these media. At physiologically relevant V concentrations (<50 μM), this role of RBC may promote the formation of V(III)-transferrin as a major V carrier in the blood plasma. The results reported herein have broad implications for the roles of RBC in the transport and speciation of metal pro-drugs that have broad applications across medicine.

Reactivity-activity relationships of oral anti-diabetic vanadium complexes in gastrointestinal media: an X-ray absorption spectroscopic study

The reactions of oral V(V/IV) anti-diabetic drugs within the gastrointestinal environment (particularly in the presence of food) are a crucial factor that affects their biological activities, but to date these have been poorly understood. In order to build up reactivity-activity relationships, the first detailed study of the reactivities of typical V-based anti-diabetics, Na3V(V)O4 (A), [V(IV)O(OH2)5](SO4) (B), [V(IV)O(ma)2] (C, ma = maltolato(-)) and (NH4)[V(V)(O)2(dipic)] (D, dipic = pyridine-2,5-dicarboxylato(2-)) with simulated gastrointestinal (GI) media in the presence or absence of food components has been performed by the use of XANES (X-ray absorption near edge structure) spectroscopy. Changes in speciation under conditions that simulate interactions in the GI tract have been discerned using correlations of XANES parameters that were based on a library of model V(V), V(IV), and V(III) complexes for preliminary assessment of the oxidation states and coordination numbers. More detailed speciation analyses were performed using multiple linear regression fits of XANES from the model complexes to XANES obtained from the reaction products from interactions with the GI media. Compounds B and D were relatively stable in the gastric environment (pH ∼ 2) in the absence of food, while C was mostly dissociated, and A was converted to [V10O28](6-). Sequential gastric and intestinal digestion in the absence of food converted A, B and D to poorly absorbed tetrahedral vanadates, while C formed five- or six-coordinate V(V) species where the maltolato ligands were likely to be partially retained. XANES obtained from gastric digestion of A-D in the presence of typical food components converged to that of a mixture of V(IV)-aqua, V(IV)-amino acid and V(III)-aqua complexes. Subsequent intestinal digestion led predominantly to V(IV) complexes that were assigned as citrato or complexes with 2-hydroxyacidato donor groups from other organic compounds, including certain carbohydrates. The absence of strong reductants (such as ascorbate) in the food increased the V(V) component in gastrointestinal digestion products. These results can be used to predict the oral bioavailability of various types of V(V/IV) anti-diabetics, and the effects of taking such drugs with food.

Toxicity of nano molybdenum trioxide toward invasive breast cancer cells

Current chemotherapy is limited by the nature of invasive cancer cells, which are similar to cancer stem cells. Nanomaterials provide a potential alternate mode of cancer therapy. This study investigated the cytotoxicity of molybdenum trioxide (MoO3) nanoplates toward invasive breast cancer iMCF-7 cells by analyzing morphological changes and performing Western blot and flow cytometry analyses. The findings suggested that MoO3 exposure induces apoptosis and generates reactive oxygen species (ROS) in iMCF-7 cells. This study revealed the potential utility of MoO3 for treating metastatic cancer cells, which might enable advancements in cancer therapy.

Biotransformations of anticancer ruthenium(III) complexes: an X-ray absorption spectroscopic study

An anti-metastatic drug, NAMI-A ((ImH)[Ru(III) Cl4 (Im)(dmso)]; Im=imidazole, dmso=S-bound dimethylsulfoxide), and a cytotoxic drug, KP1019 ((IndH)[Ru(III) Cl4 (Ind)2 ]; Ind=indazole), are two Ru-based anticancer drugs in human clinical trials. Their reactivities under biologically relevant conditions, including aqueous buffers, protein solutions or gels (e.g, albumin, transferrin and collagen), undiluted blood serum, cell-culture medium and human liver (HepG2) cancer cells, were studied by Ru K-edge X-ray absorption spectroscopy (XAS). These XAS data were fitted from linear combinations of spectra of well-characterised Ru compounds. The absence of XAS data from the parent drugs in these fits points to profound changes in the coordination environments of Ru(III) . The fits point to the presence of Ru(IV/III) clusters and binding of Ru(III) to S-donor groups, amine/imine and carboxylato groups of proteins. Cellular uptake of KP1019 is approximately 20-fold higher than that of NAMI-A under the same conditions, but it diminishes drastically after the decomposition of KP1019 in cell-culture media, which indicate that the parent complex is taken in by cells through passive diffusion.

X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples

As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts.

Metal-based anti-diabetic drugs: advances and challenges

The current status and likely future directions of complexes of V(V/IV), Cr(III), Mo(VI), W(VI), Zn(II), Cu(II), and Mn(III) as potential oral drugs against type 2 diabetes are reviewed. We propose a unified model of extra- and intracellular mechanisms of anti-diabetic efficacies of V(V/IV), Mo(VI), W(VI), and Cr(III), centred on high-oxidation-state oxido/peroxido species that inhibit protein tyrosine phosphatases (PTPs) involved in insulin signalling. The postulated oxidative mechanism of anti-diabetic activity of Cr(III) via carcinogenic Cr(VI/V) (which adds to safety concerns) is consistent with recent clinical trials on Cr(III) picolinate, where activity was apparent only in patients with poorly controlled diabetes (high oxidative stress), and the correlation between the anti-diabetic activities and ease of oxidation of Cr(III) supplements and their metabolites in vivo. Zn(II) and Cu(II) anti-diabetics act via different mechanisms and are unlikely to be used as specific anti-diabetics due to their diverse and unpredictable biological activities. Hence, future research directions are likely to centre on enhancing the bioavailability and selectivity of V(V/IV), Mo(VI), or W(VI) drugs. The strategy of potentiating circulating insulin with metal ions has distinct therapeutic advantages over interventions that stimulate the release of more insulin, or use insulin mimetics, because of many adverse side-effects of increased levels of insulin, including increased risks of cancer and cardiovascular diseases.