Arsenic trioxide binding to serum proteins

Plasma protein binding of arsenic species in acute promyelocytic leukemia patients and their relationships with hepatic and renal function

OBJECTIVES

Percentage protein binding (%PB) of arsenic species in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide remains unclear. It can be different depending on the status of hepatic or renal function.

METHODS

This study obtained steady-state blood samples from normal APL patients and those with hepatic or renal impairment. %PB of inorganic arsenic (iAs), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) was determined by analyzing free and total plasma concentrations using ultrafiltration method by HPLC-HG-AFS.

RESULTS

There is a linear relationship between free and total plasma concentrations for iAs (r2 = 0.952), MMAV (r2 = 0.603), and DMAV (r2 = 0.945). For patients with normal hepatic and renal function, mean %PB was as follows: iAs at 26.7 ± 14.3%, MMAV at 53.3 ± 11.9%, and DMAV at 24.7 ± 7.8%. %PB decreased in patients with renal impairment, with MMAV and DMAV showing statistically significant differences (p < 0.05 for MMAV, p < 0.01 for DMAV). No significant differences in %PB between normal and hepatic impairment group were observed.

CONCLUSION

Free arsenic species fraction can be estimated by total concentration. DMAV and iAs present low %PB, while MMAV exhibits a relatively high %PB in plasma. Level of %PB is more likely to be affected by renal function and age.

Spectroscopic investigation and structural simulation in human serum albumin with hydroxychloroquine/Silybum marianum and a possible potential COVID-19 drug candidate

In this study, the interaction between human serum albumin (HSA) and the hydroxychloroquine/Silybum marianum (HCQ/SM) mixture was investigated using various techniques. The observed high binding constant (Kb) and Stern-Volmer quenching constant (KSV) indicate a strong binding affinity between the HCQ/SM mixture and HSA. The circular dichroism (CD) analysis revealed that HCQ/SM induced conformational changes in the secondary structure of HSA, leading to a decrease in the α-helical content. UV-Vis analysis exhibited a slight redshift, indicating that the HCQ/SM mixture could adapt to the flexible structure of HSA. The experimental results demonstrated the significant conformational changes in HSA upon binding with HCQ/SM. Theoretical studies were carried out using molecular dynamics simulation via the Gromacs simulation package to explore insights into the drug interaction with HSA-binding sites. Furthermore, molecular docking studies demonstrated that HCQ/SM-HSA exhibited favorable docking scores with the receptor (5FUZ), suggesting a potential therapeutic relevance in combating COVID-19 with a value of -6.24 kcal mol-1. HCQ/SM exhibited stronger interaction with both SARS-CoV-2 virus main proteases compared to favipiravir. Ultimately, the experimental data and molecular docking analysis presented in this research offer valuable insights into the pharmaceutical and biological properties of HCQ/SM mixtures when interacting with serum albumin.

AS1411aptamer conjugated liposomes for targeted delivery of arsenic trioxide in mouse xenograft model of melanoma cancer

Development of AS1411aptamer-conjugated liposomes for targeted delivery of arsenic trioxide is the primary goal of this study. AS1411aptamer was used as ligand to target nucleolin, which is highly expressed on the surface of melanoma cancer cells. The targeted liposomes were constructed by the thin film method, and arsenic trioxide was loaded as cobalt (II) hydrogen arsenite (CHA) to increase the loading efficiency and stability of the liposomes. The liposomal structure was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM). In addition, particle sizes and zeta potential of the CHA-loaded liposomes (CHAL) and aptamer-functionalized CHA-loaded liposomes (AP-CHAL) were determined. In vitro cytotoxicity of CHAL and AP-CHAL were evaluated using MTT assay in murine melanoma (B16) and mouse embryonic fibroblast (MEF) cell lines. The encapsulation efficiency of CHAL and AP-CHAL was reported as 60.2 ± 6.5% and 58.7 ± 4.2%, respectively. In vivo antitumor activity of CHAL and AP-CHAL in the B16 tumor-xenograft mouse model was dramatically observed. All mice of both groups survived until the end of treatment and showed body weight gain. The tumor protrusion completely disappeared in 50% of the mice in these groups. Furthermore, histopathology studies demonstrated that CHAL and AP-CHAL did not induce significant toxicity in healthy mice tissues. However, unlike the CHAL group, which showed an initial increase in tumor volume, a specific antitumor effect was observed in the AP-CHAL group from the beginning of treatment. The results showed that AP-CHAL can be used as an effective drug delivery system with high potential in the treatment of solid tumors.

Thiolated chitosan nanoparticles for stable delivery and smart release of As2O3 for liver cancer through dual actions

In this work, multifunctional thiolated chitosan derivatives (DCA-CS-PEG-FA-NAC) were synthesized, and arsenic trioxide (ATO) was loaded onto the derivatives through glutathione (GSH)-sensitive As^III-S bonds, and stable CS-ATO nanodrugs were prepared by simple self-assembly method. By adjusting the thiol substitution degree of CS, the drug loading capacity of the nanodrugs was significantly improved, which could reach 20 ATO per CS molecule (DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO). In vitro release studies obviously showed the low leakage of ATO under physiological conditions while over 95 % ATO was released after 24 h under GSH. In vitro and in vivo investigations demonstrated that the DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO nanodrug could significantly enhance the tumor intracellular accumulation of ATO, reduce the toxic and side effects of ATO on healthy organs, and improve the therapeutic effect of ATO on the HepG2 mice tumor model (tumor inhibition rate was as high as 86.4 %), indicating the potential application of ATO in clinical treatment of liver cancer.

Albumin-Embellished Arsenic Trioxide-Loaded Polymeric Nanoparticles Enhance Tumor Accumulation and Anticancer Efficacy via Transcytosis for Hepatocellular Carcinoma Therapy

Arsenic trioxide (ATO) has efficient anticancer effect on hepatocellular carcinoma (HCC) in clinical trials, but its off-target distribution and side effects have limited its use. Here, we demonstrate an albumin-embellished ATO-loaded polyethylene glycol-polycaprolactone-polyethyleneimine (PEG-PCL-PEI) nanoparticle (AATONP) to enhance the tumor distribution and intratumor drug release of ATO for HCC therapy. AATONP is prepared by surface embellishment with albumin on the cationic ATO-loaded PEG-PCL-PEI nanoparticles (CATONP). Albumin embellishment can reduce the cationic material's hemolytic toxicity in blood cells while maintaining the rapid internalization and lysosome escape abilities of the positively charged CATONP. AATONP provides sustained and low pH-responsive drug release, facilitating the targeted drug release in the intratumor acidic microenvironment. Moreover, AATONP can significantly improve the circulation time and tumor distribution of ATO via albumin-mediated transcytosis in HCC tumor-bearing mice. Compared with free ATO and the clinically used nanomedicine Genexol/PM, AATONP shows potent antitumor activity against a human HCC xenograft mouse model, leading to a higher tumor inhibition rate of 89.4% in HCC therapy. In conclusion, this work presents an efficient strategy to achieve tumor accumulation and the intratumor drug release of ATO for HCC therapy. An albumin-embellished arsenic trioxide (ATO)-loaded polyethylene glycol-polycaprolactone-polyethyleneimine nanoparticle (AATONP) is designed to enhance tumor distribution and intratumor drug release of ATO for hepatocellular carcinoma therapy. AATONP can achieve enhanced tumor distribution via albumin-mediated transcytosis and exhibit intratumor drug release of ATO via tumor acidic microenvironment-response, leading to potent antitumor activity.

Mineral medicine: from traditional drugs to multifunctional delivery systems

Mineral drugs are an important constituent of traditional Chinese medicine (TCM). Taking minerals that contain heavy metals as drugs is a very national characteristic part of TCM. However, the safety and scientific nature of mineral drugs are controversial owing to their heavy metals and strong toxicity. In 2000, the Food and Drug Administration (FDA) authorized arsenic trioxide (ATO) as first-line therapy for acute promyelocytic leukemia. This makes the development and utilization of mineral drugs become a research hotspot. The development of nanomedicine has found a great prospect of mineral drugs in nano-delivery carriers. And that will hold promise to address the numerous biological barriers facing mineral drug formulations. However, the studies on mineral drugs in the delivery system are few at present. There is also a lack of a detailed description of mineral drug delivery systems. In this review, the advanced strategies of mineral drug delivery systems in tumor therapy are summarized. In addition, the therapeutic advantages and research progress of novel mineral drug delivery systems are also discussed. Here, we hope that this will provide a useful reference for the design and application of new mineral drug delivery systems.

Effect of different DOM components on arsenate complexation in natural water

Dissolved organic matter (DOM) and dissolved ions are two integral parameters to affect the environmental fate of As in different ways. Numerous studies chose surrogate of DOM, humic substances (HSs), to investigate the As complexation behavior. However, microbial secretion (protein and polysaccharide) was also considered for a great proportion in surface aquatic system, and its effect was still not fully understood. The present research distinguished the As complexation behavior with different DOM components (HSs, protein, polysaccharide and synthetic organic matter) in natural and simulated water samples. The results indicated that different DOM components exhibited various binding capacities for As. HSs showed the strongest affinity for As, followed by long-chain compounds (polysaccharide and synthetic organic matter) and proteins. In water source, HSs were probably the primary parameter for As complexation. In eutrophic water system, however, polysaccharide maybe the main DOM component to bind As. Cationic bridge function was prone to occur in the presence of HSs, but not observed in the presence of protein. PO₄^3- competed for binding sites with As, consequently decreasing the As complexation with all the DOM components. The research implied that a comprehensive and meticulous analyses of DOM fractions and coexist ions are the prerequisite to understanding the behavior of As (or other pollutants) in different natural aquatic systems.

Binding of pyridoxal, pyridoxal 5'-phosphate and derived hydrazones to bovine serum albumin in aqueous solution

In the present paper, the kinetics of a reaction between bovine serum albumin (BSA) and pyridoxal, pyridoxal 5'-phosphate was studied, apparent rate constant of product formation and dissociation as well as binding constants were determined. Pyridoxal 5'-phosphate hydrazones of isonicotinic, picolinic, 2-furoic, thiophene-2-carboxylic, pyrazinoic acids binding to BSA was studied by spectrofluorimetry, stability constants of the associates were calculated from experimental data using maximal likelihood approach. The changes in the secondary structure of BSA induced by hydrazones addition were studied by IR spectroscopy. New freely available software for curve fitting was developed as a part of the software kit designed for the solution chemistry and used for a specific problem of this study, IR spectra processing.

Hepatic Arterial Chemoembolization With Arsenic Trioxide Eluting CalliSpheres Microspheres Versus Lipiodol Emulsion: Pharmacokinetics And Intratumoral Concentration In A Rabbit Liver Tumor Model

BACKGROUND

The objective of this study was to investigate the plasma pharmacokinetic profiles, intratumoral concentration and tissue distribution of arsenic trioxide (ATO) by drug-eluting beads (DEB)-transcatheter arterial chemoembolization (TACE) compared with conventional TACE (cTACE) in a rabbit liver tumor model.

METHODS

Sixty-four rabbits with VX2 liver tumor were established and randomly assigned to four groups equally. The calliSpheres microspheres (CSM)-ATO group received DEB-TACE treatment using ATO-loaded CSM; the cTACE-ATO group received cTACE treatment using ATO mixed with lipiodol; the CSM-normal control (NC) group received DEB-TACE treatment using blank CSM; the TAE-lipiodol group received cTACE treatment using saline mixed with lipiodol. ATO concentration in plasma, tumor and normal tissues, and liver and kidney function indexes were evaluated.

RESULTS

The CSM-ATO group exhibited lower plasma ATO concentrations at 10 minutes and 20 minutes post treatment compared with the cTACE-ATO group. Meanwhile, intratumoral ATO concentrations were higher in the CSM-ATO group compared with the cTACE-ATO group at 3-, 7- and 14-days post treatment. In normal liver tissue, heart and muscle tissues, ATO concentrations between the CSM-ATO and cTACE groups were similar at each time point; in kidney and lung tissues, ATO concentrations were lower in the CSM-ATO group at 1-day post treatment while they were similar at 3, 7 and 14 days post treatment. Also, liver or kidney function indexes were of no difference at each time point between CSM-ATO and cTACE-ATO groups.

CONCLUSION

Administration of ATO via DEB-TACE decreases systemic concentration while increasing intratumoral concentration of ATO without increasing liver or kidney toxicity compared with cTACE.

Surface-modified PLGA nanoparticles with PEG/LA-chitosan for targeted delivery of arsenic trioxide for liver cancer treatment: Inhibition effects enhanced and side effects reduced

Arsenic trioxide (As₂O₃), an effective drug for leukemia, is limited to be used for solid tumor treatment due to its high side effects. In this study, polyethylene glycol (PEG) and lactobionic acid (LA) modified chitosan (PLC) was synthesized and was used to coat poly(lactide-co-glycolide) (PLGA) nanoparticles for encapsulation and targeted release of As₂O₃ in liver cancer treatment. The As₂O₃-loaded PLGA/PLC nanoparticles (As₂O₃-PLGA/PLC NPs) were fabricated through double emulsion-solvent evaporation method and were optimized by orthogonal tests. As₂O₃-PLGA/PLC NPs presented suitable physical stability, positive charge, high encapsulation efficiency and drug loading, and good biocompatibility. As expected, the NPs can quickly release enough dose of As₂O₃ in a short time and then sustain the drug concentration. The As₂O₃-PLGA/PLC NPs showed effective inhibition of SMMC-7721 cells while having lower cytotoxicity against normal human liver cells (LO2 cells). Furthermore, In vivo study showed that the NPs did not present toxic effects on kidney and liver, but showed relatively high growth inhibition effect on liver tumor. Therefore, this PLGA/PLC NPs could be an effective and safe drug delivery system for liver cancer chemotherapy.

RGD conjugated liposome-hollow silica hybrid nanovehicles for targeted and controlled delivery of arsenic trioxide against hepatic carcinoma

The aim of our study was to construct an Arg-Gly-Asp (RGD)-conjugated liposome-hollow silica hybrid nanovehicle for targeted delivery and controlled release of arsenic trioxide (ATO), whose anti-solid tumor effect was hampered by poor pharmacokinetics and dose-limited toxicity. Hydrophobic interactions were used to attach intact lipid membrane to the surface of chlorodimethyloctadecylsilane-modified hollow mesoporous silica nanoparticles. The prepared nanovehicles (RGD-LP-CHMSN) were characterized for uniform structure (silica core of ∼140nm in diameter and liposomal shell of ∼6nm), comparable drug loading efficiency (6.76%), desirable stability and strengthened controlled release. In vitro, RGD-LP-CHMSN showed good biocompatibility and low toxicity on HepG2, MCF-7 and LO2 cells. The targeted delivery of ATO by nanocarriers (RGD-LP-CHMSN-ATO) was demonstrated by an enhanced cellular uptake and a reduced half maximal inhibitory concentration (IC₅₀) value. In pharmacokinetic studies, the RGD-LP-CHMSN-ATO group, compared to the free ATO group, prolonged the half time (t_1/2β) by 1.7 times and increased the area under curve (AUC) by 2.4 times. In addition, in a H22 tumor-xenograft mouse model, nanovehicles improved the targeting efficiency and anticancer potential of ATO. In conclusion, the strategy of constructing a nanocarrier with targeted delivery and controlled release characteristics is prospective to enhance the antitumor effect of ATO.

Interactions of two food colourants with BSA: Analysis by Debye-Hückel theory

We have focused on exploring pH- and ionic strength-modulated binding of acid red 1 (AR1) and acid green 50 (AG50) with bovine serum albumin (BSA) by fluorescence, UV-vis absorption and FTIR spectra. The results implied that the quenching mechanism of BSA-AR1/AG50 system was a static quenching, electrostatic force dominated the formation of BSA-AR1/AG50 complex, and the binding affinity of AR1 was greater than that of AG50 on the subdomain IIA of BSA. Moreover, their true thermodynamic binding constant (Keq), true free energy change (ΔG(0)I→0), and effective charge (ZP) in the anion receptor pocket of BSA were calculated using Debye-Hückel limiting law. The local charge bound by AR1/AG50 rather than the overall or surface charge of BSA played a key role in determining their interaction strength. Besides, the thermal and structural stabilization of BSA was discussed by analyzing the changes of Tm and Hurea without/with the addition of AR1/AG50, respectively.

Combined computational and experimental studies of molecular interactions of albuterol sulfate with bovine serum albumin for pulmonary drug nanoparticles

Albumin-based nanoparticles (NPs) are a promising technology for developing drug-carrier systems, with improved deposition and retention profiles in lungs. Improved understanding of these drug–carrier interactions could lead to better drug-delivery systems. The present study combines computational and experimental methods to gain insights into the mechanism of binding of albuterol sulfate (AS) to bovine serum albumin (BSA) on the molecular level. Molecular dynamics simulation and surface plasmon resonance spectroscopy were used to determine that there are two binding sites on BSA for AS: the first of which is a high-affinity site corresponding to AS1 and the second of which appears to represent the integrated functions of several low-affinity sites corresponding to AS2, AS3, and AS8. AS1 was the strongest binding site, established via electrostatic interaction with Glu243 and Asp255 residues in a hydrophobic pocket. Hydrogen bonds and salt bridges played a main role in the critical binding of AS1 to BSA, and water bridges served a supporting role. Based upon the interaction mechanism, BSA NPs loaded with AS were prepared, and their drug-loading efficiency, morphology, and -release profiles were evaluated. Successful clinical development of AS-BSA-NPs may improve therapy and prevention of bronchospasm in patients with reversible obstructive airway disease, and thus provide a solid basis for expanding the role of NPs in the design of new drug-delivery systems.

High Yield Production and Radiochemical Isolation of Isotopically Pure Arsenic-72 and Novel Radioarsenic Labeling Strategies for the Development of Theranostic Radiopharmaceuticals

Radioisotopes of arsenic are of considerable interest to the field of nuclear medicine with unique nuclear and chemical properties making them well-suited for use in novel theranostic radiopharmaceuticals. However, progress must still be made in the production of isotopically pure radioarsenic and in its stable conjugation to biological targeting vectors. This work presents the production and irradiation of isotopically enriched (72)Ge(m) discs in an irrigation-cooled target system allowing for the production of isotopically pure (72)As with capability on the order of 10 GBq. A radiochemical separation procedure isolated the reactive trivalent radioarsenic in a small volume buffered aqueous solution, while reclaiming (72)Ge target material. The direct thiol-labeling of a monoclonal antibody resulted in a conjugate exhibiting exceptionally poor in vivo stability in a mouse model. This prompted further investigations to alternative radioarsenic labeling strategies, including the labeling of the dithiol-containing chelator dihydrolipoic acid, and thiol-modified mesoporous silica nanoparticles (MSN-SH). Radioarsenic-labeled MSN-SH showed exceptional in vivo stability toward dearsenylation.