Synthesis, characterization and biological activity of a niobium-substituted-heteropolytungstate on hepatitis B virus

New composition of tungsten has a broad range of antiviral activity

The water-based combination of two inorganic chemical compounds such as sodium tungstate dihydrate-Na₂WO₄ × 2H₂O and Aluminum sulfate octadecahydrate-Al₂ (SO₄) 3 × 18H₂O that we have conditionally named ‘Vomifal’ has a broad antiviral activity in various DNA and RNA viruses, including Human Herpes Virus (HHV), African Swine Fever Virus (ASFV), Vaccinia Virus (VV), Hepatitis C Virus (HCV), Foot and Mouth Disease Virus (FMDV), Influenza A virus (A/Aichi/2/68 (H3N2)). In vitro and In vivo assays in several tissue cultures as well as in laboratory animals, conformed ‘Vomifal’ has a very low toxicity and the antiviral properties partially are due to its ability to induce gamma-IFN. Based on the results obtained, we can assume the presence of at least two mechanisms of the antiviral action of the studied drug. First or early stage - an unknown mechanism, possibly related to the effect on cellular receptors. Second or late stage – main antiviral properties probably associated with an interferonogenic effect.

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.

Antiviral effects of a niobium-substituted heteropolytungstate on hepatitis B virus-transgenic mice

To study the efficacy of a polyoxometalate, Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O, as an antiviral treatment in HBV transgenic mice. HBV transgenic mice were treated with Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O by intragastric administration. Adefovir and distilled water were administered as controls. Serum HBV DNA, liver HBV RNA levels were measured by quantitative RT-PCR. Serum HBsAg levels were measured by ELISA. The hepatitis B virus surface antigen (HBsAg) in liver cells was detected by immunohistochemistry (IHC). Pathological changes in the liver tissues were also observed by light and electron microscopy. Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O significantly decreased serum HBsAg and HBV DNA levels. Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O resulted in a 98% decrease in serum HBV DNA at 28 days, from 4.3 log₁₀ copies/ml at baseline to 2.5 log₁₀ copies/ml after treatment, and the inhibition rate of HBV DNA was higher than ADV at the same dose. The HBV replication levels in each group slightly increased at 7 days after withdrawal, but rebounded slightly more in the Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O treatment group compared to the H₂ O control group (p < .05). There were no differences in HBV RNA levels. No significant differences were observed in the pathology, but there were decreased HBsAg levels in the Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O-treated group compared to the control group. The results demonstrated that Cs₂ K₄ Na[SiW₉ Nb₃ O₄₀ ]·H₂ O displayed potent anti-HBV activity in HBV transgenic mice and supported for future clinic study.

Genotoxicity and acute and subchronic toxicity studies of a bioactive polyoxometalate in Wistar rats

Background

Cs₂K₄Na [SiW₉Nb₃O₄₀] (POM93) is a novel broad-spectrum antiviral agent with high activity, high stability, and low toxicity in vitro. Most toxicity studies for POM93 have been performed in cultured cell lines rather than in animals. Like other POMs, there is a lack of evidence for in vivo toxicity limits, oral bioavailability, and therapeutic applications.

Methods

The toxic properties of POM93 were evaluated comprehensively in vivo, including the acute and subchronic oral toxicity studies and genotoxicity tests.

Results

The acute toxicity study showed no abnormal changes or mortality in rats treated with POM93 even at the single high dose of 5000 mg/kg body weight. In the subchronic toxicity study, regardless of the body weight, the organ weight, and the hematological parameters, similar results were observed between the control group and the experimental groups. POM93 produced mild changes in rare hematological parameters in the liver and kidneys, but did not induce the clinical symptoms of liver or kidneys injury in rats as confirmed by histopathological analysis. Moreover, neither mutagenicity nor clastogenicity was caused by POM93 treatment in vitro and in vivo.

Conclusions

The present study demonstrates that the oral administration of POM93 is presumed safe and poses a low risk of potential health risks.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0133-x) contains supplementary material, which is available to authorized users.

Recent advance of the hepatitis B virus inhibitors: a medicinal chemistry overview

Hepatitis B Virus (HBV) is one of the most prevalent viral infections of human worldwide. The therapies are limited in the clinical context because of negative side effects of interferons and the development of viral resistance to the nucleoside/nucleotide inhibitors. In this review, we summarize the recent advances in design and development of potent anti-HBV inhibitors from natural sources and synthetic compounds, targeting different steps in the life cycle of HBV. We attempt to emphasize the major structural modifications, mechanisms of action and computer-aided docking analysis of novel potent inhibitors that need to be addressed in the future to design potent anti-HBV molecules.

The elements of life and medicines

Which elements are essential for human life? Here we make an element-by-element journey through the periodic table and attempt to assess whether elements are essential or not, and if they are, whether there is a relevant code for them in the human genome. There are many difficulties such as the human biochemistry of several so-called essential elements is not well understood, and it is not clear how we should classify elements that are involved in the destruction of invading microorganisms, or elements which are essential for microorganisms with which we live in symbiosis. In general, genes do not code for the elements themselves, but for specific chemical species, i.e. for the element, its oxidation state, type and number of coordinated ligands, and the coordination geometry. Today, the biological periodic table is in a position somewhat similar to Mendeleev's chemical periodic table of 1869: there are gaps and we need to do more research to fill them. The periodic table also offers potential for novel therapeutic and diagnostic agents, based on not only essential elements, but also non-essential elements, and on radionuclides. Although the potential for inorganic chemistry in medicine was realized more than 2000 years ago, this area of research is still in its infancy. Future advances in the design of inorganic drugs require more knowledge of their mechanism of action, including target sites and metabolism. Temporal speciation of elements in their biological environments at the atomic level is a major challenge, for which new methods are urgently needed.

Broad-spectrum antiviral property of polyoxometalate localized on a cell surface

Cs2K4Na[SiW9Nb3O40] has broad antiviral ability including anti-Influenza A, -Influenza B, -HSV-1, -HSV-2, -HIV-1, and -HBV. A series of antivirus and/or biochemical experiments and X-ray nanotomography analysis confirm that this kind of broad-spectrum antiviral property is mainly due to its localization on the cell surface.

Pharmacokinetics of anti-HBV polyoxometalate in rats

Polyoxometalates are non-nucleoside analogs that have been proven to exhibit broad-spectrum antiviral activity. In particular, Cs₂K₄Na[SiW₉Nb₃O₄₀].H₂O 1 shows low toxicity and high activity against HBV. The preclinical pharmacokinetics of Compound 1 in rats were characterized by establishing and applying inductively coupled plasma-mass spectrometry method to determine the concentration of W in plasma, urine, feces, bile and organ samples. The quantitative ICP-MS method demonstrated good sensitivity and application in the pharmacokinetics study of polyoxometalates. The pharmacokinetic behavior of Compound 1 after intravenous or oral administration fit a two-compartment model. T_max ranges from 0.1 h to 3 h and the T_1/2 of Compound 1 is between 20 h and 30 h. The absolute bioavailability of Compound 1 at 45, 180 and 720 mg/kg groups were 23.68%, 14.67% and 11.93%, respectively. The rates of plasma protein binding of Compound 1 at 9, 18 and 36 mg/ml of Compound 1 are 62.13±9.41%, 71.20±24.98% and 49.00±25.59%, respectively. Compound 1 was widely distributed throughout the body, and high levels of compound 1 were found in the kidney and liver. The level of Compound 1 in excretion was lower: 30% for urine, 0.28% for feces and 0.42% for bile, respectively. For elaborate pharmacokinetic characteristics to be fully understood, the metabolism of Compound 1 needs to be studied further.

IL-17A but not IL-22 suppresses the replication of hepatitis B virus mediated by over-expression of MxA and OAS mRNA in the HepG2.2.15 cell line

Interleukin-17A (IL-17A) and interleukin-22 (IL-22), mainly secreted by interleukin-17-producing T help cells (Th17), are pleiotropic cytokines that regulate the biological responses of several target cells, including hepatocytes. Th17 frequency was reported to negatively correlate with plasma hepatitis B virus (HBV) DNA load in patients with HBV infection. Several studies have indicated that cytokines, such as IL-6 and IL-4, are involved in the noncytopathic suppression of HBV replication. We therefore hypothesized that IL-17A and IL-22 might have a potent suppressive effect on HBV replication. In our present study, we analyzed the suppressive effect of IL-17A and IL-22 on HBV replication in the hepatocellular carcinoma cell line HepG2.2.15. IL-17A did not inhibit the proliferation of HepG2.2.15 cells. It decreased the levels of HBV s antigen (HBsAg) and HBV e antigen (HBeAg) in culture medium and the levels of intracellular HBV DNA. By contrast, blockage of IL-17 receptor (IL-17R) increased the levels of HBsAg and extracellular HBV DNA in culture medium and the levels of intracellular HBV DNA. The expression of antiviral proteins, including myxovirus resistance A (MxA) and oligoadenylate synthetase (OAS), was enhanced by IL-17A. IL-22 and anti-human IL-22 receptor (IL-22R) antibody did not change any indexes. We demonstrated that IL-17A effectively suppressed HBV replication in a noncytopathic manner and the over-expression of MxA and OAS mRNA was involved in the suppression of HBV replication by IL-17A.