Realgar Nanoparticles Research Articles

Critical Review on the Effect and Mechanism of Realgar Nanoparticles on Lymphoma: State of the Art on In-Vitro Biomedical Studies.

Lymphoma is a malignant tumor caused by abnormal proliferation of lymphocytes in the lymphatic system. Conventional treatments for lymphoma often have limitations, and new therapeutic strategies need to be explored. Realgar is an ancient Chinese medicine that has been used for centuries to treat a variety of ailments due to its therapeutic potential for various diseases, including cancer. However, it is a time-consuming waste and has a low absorption rate in the gastrointestinal tract, so it has the disadvantages of oral dose, potential toxicity, and low bioavailability. Recently, the development of nanotechnology has promoted the nanization of realgar particles, which have better physicochemical properties and higher bioavailability. The antitumor activity of Realgar nanoparticles against lymphoma has been demonstrated in preclinical studies. Realgar nanoparticles exhibit cytotoxic effects by inducing apoptosis and inhibiting the growth and proliferation of lymphoma cells. Moreover, these nanoparticles exert immunomodulatory effects by enhancing the activity of immune cells and promoting the cytotoxicity of T lymphocytes against lymphoma cells. Additionally, realgar nanoparticles have been shown to inhibit tumor angiogenesis, thereby restricting the blood supply and nutrient availability to lymphoma cells. Despite promising preclinical data, further research on the role and mechanism of realgar nanoparticles in the treatment of lymphoma remains to be studied. Moreover, the translation of these findings into clinical practice requires rigorous evaluation through well-designed clinical trials. Realgar nanoparticles hold great potential as a novel therapeutic approach for lymphoma, and their development may contribute to the advancement of precision medicine in the field of oncology.

Realgar Nanoparticles Inhibit Migration, Invasion and Metastasis in a Mouse Model of Breast Cancer by Suppressing Matrix Metalloproteinases and Angiogenesis.

Realgar, a traditional Chinese medicine, has shown antitumor efficacy in several tumor types. We previously showed that realgar nanoparticles (nano-realgar) had significant antileukemia, anti-lung cancer and anti-liver cancer effects. In addition, the anti-tumor effects of nanorealgar were significantly better than those of ordinary realgar. To explore the inhibitory effects and molecular mechanisms of nano-realgar on the migration, invasion and metastasis of mouse breast cancer cells. Wound-healing migration assays and Transwell invasion assays were carried out to determine the effects of nano-realgar on breast cancer cell (4T1) migration and invasion. The expression levels of matrix metalloproteinase (MMP)-2 and -9 were measured by Western blot. A murine breast cancer metastasis model was established, administered nano-realgar for 32 days and monitored for tumor growth and metastasis by an in vivo optical imaging system. Finally, living imaging and hematoxylin and eosin (HE) staining were used to measure the morphology and pathology of lung and liver cancer cell metastases, respectively. Angiogenesis was assessed by CD34 immunohistochemistry. Nano-realgar significantly inhibited the migration and invasion of breast cancer 4T1 cells and the expression of MMP-2 and -9. Meanwhile, nano-realgar effectively suppressed the abilities of tumor growth, metastasis and angiogenesis in the murine breast cancer metastasis model in a time- and dosedependent manner. Nano-realgar significantly inhibited migration and invasion of mouse breast cancer cells in vitro as well as pulmonary and hepatic metastasis in vivo, which may be closely correlated with the downexpression of MMP-2 and -9 and suppression of tumor neovascularization.

Reno-Protective Effect of Realgar Nanoparticles on Lupus Nephritis of MRL/Lpr Mice through STAT1.

Realgar, an arsenic tetrasulfide compound, is a highly recognized traditional Chinese medicinal prescription that has been widely used to treat various diseases such as inflammatory diseases. However, there are still some problems in the clinical treatment of Realgar, such as large oral dose and high potential toxicity. To evaluate effects of Realgar nanoparticles on lupus nephritis (LN) in vivo in MRL/lpr mice. Ten-week mice were orally administered every day for eight consecutive weeks except the mice of normal model groups. The serum levels of anti-ds-DNA antibody IgG, IgM, IFN-γ, Creatinine (Cr), and blood urea nitrogen (BUN) were determined, and 24-hour urine protein was also measured. Renal inflammatory pathology analysis was assessed by hematoxylin-eosin (H&E) staining. The expression of phosphorylated signal transducer and activator of transcription 1 (p-STAT 1) and Janus Kinase 1 (JAK 1) in kidney tissue was determined by direct reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). The mice treated with Realgar nanoparticle in the high dose-treated (Realgar HD, 0.03 g/kg/d) group exhibited significantly reduced serum levels of anti-dsDNA (p<0.01), IgG (p<0.01), IgM (p<0.01), BUN (p<0.01), Cr (p<0.01), and inflammatory cytokine IFN-γ (p<0.01) as well as proteinuria (p<0.01) compared to the untreated model MRL/lpr mice. Additionally, high doses of Realgar nanoparticles significantly suppressed the phosphorylations of STAT 1(p<0.01) and the renal pathological changes. The study indicates that Realgar nanoparticles may be a potential agent to treat LN, and the down-regulated p-STAT1 expression suggests that it may be one of the LN treatment targets for Realgar nanoparticles.

Bioleaching of realgar nanoparticles using the extremophilic bacterium Acidithiobacillus ferrooxidans DLC-5

Background: This paper presents micro- and nano-fabrication techniques for leachable realgar using the extremophilic bacterium Acidithiobacillus ferrooxidans (A. ferrooxidans) DLC-5. Results: Realgar nanoparticles of size ranging from 120 nm to 200 nm were successfully prepared using the highenergy ball mill instrument. A. ferrooxidans DLC-5 was then used to bioleach the particles. The arsenic concentration in the bioleaching system was found to be increased significantly when compared with that in the sterile control. Furthermore, in the comparison with the bioleaching of raw realgar, nanoparticles could achieve the same effect with only one fifth of the consumption. Conclusion: Emphasis was placed on improving the dissolvability of arsenic because of the great potential of leachable realgar drug delivery in both laboratory and industrial settings.

(-)-Epigallocatechin-3-gallate encapsulated realgar nanoparticles exhibit enhanced anticancer therapeutic efficacy against acute promyelocytic leukemia

Realgar and (-)-Epigallocatechin-3-gallate (EGCG) are natural medicines that inhibit cancer cell growth, resulting in inhibition of formation and development of tumors. The anticancer effects of realgar and EGCG were greatly improved following formulation as nanoparticles. EGCG has received increased attention as a drug carrier. The aim of this study was to prepare a new nanomedicine, (EGCG-RNPs), in which encapsulated nano-realgar. EGCG-RNPs were prepared by coprecipitation and characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), particle size and zeta potential, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and in vitro release. Furthermore, we evaluated the antiproliferative effects of EGCG-RNPs on HL-60 cells in vitro, antitumor effect by intratumoral injection of EGCG-RNPs into solid tumors derived from APL HL-60 cells in vivo. Possible mechanisms were evaluated using uptake and efflux experiments in HL-60 cells. The results showed that the average particle size and zeta potentials of EGCG-RNPs was 200.3 ± 1.23 nm and −46.8 ± 1.31 mV. Controlled release of EGCG-RNPs was sustained and continued up to 72 h in vitro. Compared with nano-realgar and EGCG + RNPs (EGCG and nano-realgar physical mixing), EGCG-RNPs significantly inhibited growth of HL-60 cells. In a solid tumor model, EGCG-RNPs decreased tumor volumes, with an inhibitory rate of 60.18% at a dose of 70 mg · kg−1. The mechanisms of antitumor improvement may correlate with the increased uptake of realgar and prolonged the retention time of realgar in HL-60 cells due to EGCG as a carrier. EGCG-RNPs could enhance anticancer therapeutic efficacy for acute promyelocytic leukemia.

Combination of LC/MS and GC/MS based metabolomics to study the hepatotoxic effect of realgar nanoparticles in rats

Realgar nanoparticles (NPs) are increasingly used as therapeutic agents for their enhanced anti-proliferation effect and cytotoxicity on cancer cells. However, the alteration of particle size may enhance biological reactivity as well as toxicity. A LC/MS and GC/MS based metabolomics approach was employed to explore the mechanism of realgar NPs-induced hepatotoxicity and identify potential biomarkers. Male Sprague-Dawley rats were administrated intragastrically with realgar or realgar NPs at a dose of 1.0 g·kg−1·d−1 for 28 days and toxic effects of realgar NPs on liver tissues were examined by biochemical indicator analysis and histopathologic examination. Increased levels of serum enzymes and high hepatic steatosis were discovered in the realgar NPs treated group. Multivariate data analysis revealed that rats with realgar NPs-induced hepatotoxicity could be distinctively differentiated from the animals in the control and realgar treated groups. In addition, 21 and 32 endogenous metabolites were apparently changed in the serum and live extracts, respectively. Realgar NPs might induce free fatty acid and triglyceride accumulation, resulting in hepatotoxicity. In conclusion, the present study represents the first comprehensive LC/MS- and GC/MS-based metabolomics analysis of realgar NPs-induced hepatotoxicity, which may help further research of nanotoxicity.

Caveolin-1 contributes to realgar nanoparticle therapy in human chronic myelogenous leukemia K562 cells.

Chronic myelogenous leukemia (CML) is characterized by the t(9;22) (q34;q11)-associated Bcr-Abl fusion gene, which is an essential element of clinical diagnosis. As a traditional Chinese medicine, realgar has been widely used for the treatment of various diseases for >1,500 years. Inspired by nano-drug, realgar nanoparticles (NPs) have been prepared with an average particle size of <100 nm in a previous work. Compared with coarse realgar, the realgar NPs have higher bioavailability. As a principal constituent protein of caveolae, caveolin-1 (Cav-1) participates in regulating various cellular physiological and pathological processes including tumorigenesis and tumor development. In previous studies, it was found that realgar NPs can inhibit several types of tumor cell proliferation. However, the therapeutic effect of realgar NPs on CML has not been fully elucidated. In the present paper, it was demonstrated that realgar NPs can inhibit the proliferation of K562 cells and degrade Bcr-Abl fusion protein effectively. Both apoptosis and autophagy were activated in a dose-dependent manner in realgar NPs treated cells, and the induction of autophagy was associated with class I phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway. Morphological analysis indicated that realgar NPs induced differentiation effectively in CML cells. Furthermore, it was identified that Cav-1 might play a crucial role in realgar NP therapy. In order to study the effects of Cav-1 on K562 cells during realgar NP treatment, a Cav-1 overexpression cell model was established by using transient transfection. The results indicated that Cav-1 overexpression inhibited K562 cell proliferation, promoted endogenic autophagy, and increased the sensitivity of K562 cells to realgar NPs. Therefore, the results demonstrated that realgar NPs degraded Bcr-Abl oncoprotein, while the underlying mechanism might be related to apoptosis and autophagy, and Cav-1 might be considered as a potential target for clinical comprehensive therapy of CML.

Challenges for application of realgar: A critical review

Realgar has been not only well-known poisons but also used as healing agent. Realgar has long been used in traditional medicines for different diseases; so far arsenic can be extremely toxic and carcinogenic. In Ayurvedic and Chinese traditional medicines arsenic usually comes from conscious addition for healing purposes, mostly in the form of mineral arsenicals with orpiment (As2S3), realgar (As4S4), and arsenic trioxide (As2O3). Pharmacological studies revealed that realgar is effective against in different cancer cell line. However, it has been critically limited clinical applications because of its many disadvantages, for example, low solubility in water, high toxicity, poor gastrointestinal absorption, and bioavailability. This review evaluates the toxicology, bioaccessibility, and pharmacology of the realgar used in Ayurvedic and Chinese traditional medicines. In recent times, numerous types of realgar nanoparticles (NPs) have been developed due to insolubility of realgar in water and different media. Most of the NPs of realgar possess the exclusive optical qualities of quantum dots. The pharmacological activities and bioavailability of realgar NPs are much more partial by their sizes, building realgar an exciting biomedical and pharmaceutical research applicant.

Realgar nanoparticle-based microcapsules: preparation and in-vitro/in-vivo characterizations.

The aim of this study was to prepare microcapsules for the oral delivery of realgar nanoparticles (RN) that are also capable of improving its stability. RN and RN-based microcapsules (RNM) were prepared using ball milling and solvent evaporation techniques, respectively. Properties such as particle size, ζ-potential (ZP), morphology and X-ray diffractometer (XRD) were investigated. In addition, drug release, bioavailability and antitumour studies were also performed. The nanoparticles appeared round or elliptical in shape with a mean size of 85.4 ± 3.5 nm and a ZP of -34.3 ± 1.7 mV. The obtained RNM appeared spherical and not aggregated with a relatively narrow size distribution. XRD analysis revealed that ball milling technique did not change the crystallinity of the realgar powder. RN and RNM exhibited considerable higher release of As2 S2 , bioavailability and antitumour efficacies compared with crude realgar. Furthermore, RNM could protect RN directly exposed to the air and light, and therefore increased the stability of the RN. The developed RNM demonstrated a greater potential as a delivery system for realgar.

Morphological Investigation and Fractal Properties of Realgar Nanoparticles

Some arsenic compounds can show extraordinary polymorphism. Realgar (As4S4) is among several minerals with various crystal forms and is one of the most important sources of arsenic for pharmaceutical use. Currently, realgar is used as an arsenic source in many industries, such as weaponry, publishing, textiles, cosmetics, and health products. In this paper, we used and reported new methods for the purification, nanonization, and structural morphological investigations of As4S4 by using planetary ball mills process for nanonization of the compound. The product was characterized using X‐ray powder diffraction analysis, Fourier transform infrared spectrometry spectra, and field emission scanning electron microscope (FESEM) imaging. We investigated the morphological properties of FESEM‐imaged realgar nanoparticles by an image‐processing technique that calculates fractal dimensions using values on a computer with MATLAB software. We applied the Statistical Package for the Social Sciences software for statistics data extracted from the FESEM image and obtained the statistics results of the fractal dimension and histogram plot for the FESEM image.

Realgar (As4S4) nanoparticles and arsenic trioxide (As2O3) induced autophagy and apoptosis in human melanoma cells in vitro.

The aim of the present study was to compare the effect of realgar nanoparticles and arsenic trioxide (ATO) on viability, DNA damage, proliferation, autophagy and apoptosis in the human melanoma cell lines BOWES and A375. The application of various flow cytometric methods for measurements cell viability, DNA cell cycle, mitochondrial potential, lysosomal activity, and intracellular content of glutathione was used. In addition, quantitative PCR, western blotting and multiplex bead array analyses were applied for evaluation of redox stress, autophagic flux, and cell signaling alterations.The results showed that realgar treatment of studied cells caused modulation of cell proliferation, induced a block in G2/M phase of the cell cycle and altered phosphorylation of IκB, Akt, ERK1/2, p38, and JNK kinases, as well as decreased mitochondrial membrane potential. Additionally, it appeared that induction of cell death by both realgar and ATO was dose-dependent, when lower (0.3 µM) dosage increased lysosomal activity and induced autophagy and higher (1.25 µM) concentration resulted in the appearance of apoptosis, while pan-caspase inhibitor attenuated more efficiently realgar- than ATO-induced cell death. Furthermore, low concentrations of ATO and realgar nanoparticles increased the content of intracellular glutathione and elevated γ-H2AX expression confirmed DNA damage preferentially at higher concentrations of both drugs used. Further analysis revealed slight differences in time-dependent phosphorylation pattern due to both realgar and ATO treatments, while significant differences were noticed between cell lines. In conclusion, realgar nanoparticles and ATO treatment induced dose-dependent activation of autophagy and apoptosis in both melanoma cell lines, when autophagy flux was determined at lower drug concentrations and the switch to apoptosis occurred at higher concentrations of both arsenic forms.

Enhanced antitumor activity of realgar mediated by milling it to nanosize

Realgar is a poorly water-soluble compound that exhibits poor bioavailability. To improve this, the authors reduced the particle size of realgar to nanoscale by high-energy ball milling and optimized the preparation process under which (realgar weight 40 g, milling time 9 hours, milling speed 38 Hz, milling temperature −20°C) realgar nanoparticles (NPs) with an average size of 78±8.3 nm were prepared. The average particle size of realgar was characterized by laser scattering, and its apparent shape was observed by transmission electron microscopy and scanning electron microscopy. The solubility of realgar was enhanced after milling until the particles were in the nanoscale region without altering its properties, as confirmed by a scanning electron microscopy energy-dispersive spectrometer. Realgar NPs had higher cytotoxicity on the selected cell lines, namely human breast cancer (MCF7), human hepatoma (HepG2), and human lung cancer (A549) cell lines, than coarse realgar. In addition, a pharmacokinetics study performed in rats indicated that the relative bioavailability of realgar NPs was 216.9% compared with coarse realgar; a biodistribution study performed in mice showed that after intragastric administration of realgar NPs, higher arsenic concentration was reached in the tumor, heart, liver, spleen, lung, and kidney compared with the administration of coarse realgar, as confirmed by inductively coupled plasma mass spectrometry to determine the concentration of arsenic. This study indicated that high-energy ball milling is an effective way to reduce the average particle size of realgar, and compared with coarse realgar, the cytotoxicity and bioavailability of realgar NPs were significantly improved.

Nanoparticle Arsenic Compound Realgar Effectively Targets Myeloma Stem-Like Side Population

Introduction Tumors contain diverse sub-clones, which can lead to tumor persistence and re-growth after therapy. Previous studies suggest that multiple myeloma (MM) sub-clones may contain tumor-initiating cells which maintain growth and proliferation as well as contribute to drug-resistance. Recently, we have confirmed the existence of MM stem cell-like cells by identifying “side population” (SP) cells as an enriched source of tumor-initiating cells with clonogenic and tumorigenic stem cell properties. Targeting this population with novel therapies represents a promising strategy. Arsenic trioxide (ATO, As2O3) shows only limited responses compared to anti-MM agents such as bortezomib and lenalidomide in relapsed and refractory MM. Here we evaluated the anti-MM activity of another arsenic compound (arsenic sulfide, As4S4), used in traditional Chinese medicine with greater efficacy and less genotoxicity than ATO, prepared by milling into realgar nanoparticles (NREA). We assessed the effect of NREA on MM stem cell-like SP fraction in the context of the bone marrow stromal cells (BMSCs) to provide the rational for its clinical evaluation. Methods and Results First, we evaluated the effect of both NREA and ATO on MM cell survival. Both drugs significantly decreased survival of 13 MM cell lines in a concentration-dependent manner. Importantly, we observed more potent anti-MM effect with NREA compared to ATO, with IC50 values of NREA 2-4 times lower than ATO. Moreover, we confirmed the effect of NREA on MM cells from patients with primary relapsed/refractory disease: NREA showed a dose-dependent response, with IC50 values in the range 1-2 μM. Significant concentration-dependent increased apoptosis was observed in NREA-treated MM cells. Similarly, decreased mitochondrial membrane potential was more significantly triggered by NREA than ATO. Consequently, NREA modulated the MM cell cycle profile: concentration-dependent treatment induced either G0/G1 (MM.1S and KMS11) or G2/M arrest (RPMI-S and OPM1) at 48h. To compare in vivo anti-tumor activity of NREA and ATO, we used our xenograft murine model of human MM. Tumor-bearing mice were intraperitoneally treated with NREA, ATO or with the respective vehicle. Treatment with NREA triggered more significant tumor growth inhibition compared to ATO at day 8 of treatment. To evaluate the effect of NREA on the SP phenotype of MM cells, we treated MM cells with subtoxic concentrations of NREA and ATO for 72 h. Analysis of MM cells for low intracellular content of Hoechst 33342 (SP fraction) revealed that NREA significantly decreased the percentage of SP cells in MM cells in a dose-dependent manner, whereas increase in SP fraction was observed in ATO-treated cells. To evaluate the effect of the bone marrow microenvironment on targeting the SP cells with NREA, MM cells were cultured alone or with BMSCs, and then analyzed for low intracellular accumulation of Hoechst 33342. Treatment by NREA, but not ATO, significantly depleted SP cells in co-cultures MM cells with BMSCs. Moreover, NREA decreased clonogenic potential, whereas ATO had no effect. Similarly, tumorigenic potential of SP cells was significantly decreased by NREA, but not by ATO, treatment. Conclusions Overall, our results demonstrate significant anti-tumor activity of NREA against MM cells in vitro. Our in vivo data further show that NREA significantly decreased tumor burden at clinically achievable concentrations of arsenic. Importantly, targeting of SP cells by NREA in the context of BMSCs provides the preclinical rationale for its clinical evaluation. Disclosures: Hideshima: Acetylon Pharmaceuticals: Consultancy. Richardson:Millennium: Membership on an entity’s Board of Directors or advisory committees; Johnson &amp; Johnson: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees. Anderson:celgene: Consultancy; onyx: Consultancy; gilead: Consultancy; sanofi aventis: Consultancy; oncopep: Equity Ownership; acetylon: Equity Ownership.

Effect of stability and dissolution of realgar nano-particles using solid dispersion technology

To improve the stability and dissolution of realgar nano-particles by solid dispersion. Using polyethylene glycol 6000 and poloxamer-188 as carriers, the solid dispersions were prepare by melting method. XRD, microscopic inspection were used to determine the status of realgar nano-particles in solid dispersions. The content and stability test of As(2)0(3) were determined by DDC-Ag method. Hydride generation atomic absorption spectrometry was used to determine the content of Arsenic and investigated the in vitro dissolution behavior of solid dispersions. The results of XRD and microscopic inspection showed that realgar nano-particles in solid dispersions were amorphous. The dissolution amount and rate of Arsenic from realgar nano-particles of all solid dispersions were increased significantly, the reunion of realgar nano-particles and content of As(2)0(3) were reduced for the formation of solid dispersions. The solid dispersion of realgar nano-particles with poloxamer-188 as carriers could obviously improve stability, dissolution and solubility.

Study on realgar nanoparticles inhibition of adenovirus replication at the gene level

Modeling HAdV-3 infect Hep-2 cells in vitro. The effect of realgar nanoparticles on the expression of HAdV-3 is detected by using fluorescent quantitative PCR. The experiment is divided into four groups: Hep-2 cells control group, HAdV-3 virus control group, realgar nanoparticle group and ribavirin group. In order to detect HAdV-3 viral load, add realgar nanoparticles and ribavirin in vitro and remain that vitro for 24 hours when HAdV-3 has infected Hep-2 cells, extract total DNA of Hep-2 cells infected by HAdV-3, and establish Real-time PCR reaction system of every experimental groups. The Hep-2 cells group has no amplification curve, the Ct value is greater than 35, which illustrate HAdV-3 pathogen detection is negative. However, realgar nanoparticles group, ribavirin group and the HAdV-3 group have amplification curve, the Ct values are 29.30 +/- 0.08, 33.05 +/- 1.29, 26.01 +/- 0.25 respectively, which illustrate HAdV-3 pathogen detection is positive. The viral copy amount of the adenovirus group(66 699 932 +/- 23.85) is more than that of realgar nanoparticles group (912 435.44 +/- 16.57), and much greater than that of ribavirin group (459 124.84 +/- 12.82) (P < 0.05). The model of Hep-2 cell infected by HAdV-3 is reliable. The method of quantitative PCR is sensitive and specific. Realgar nanoparticles have a certain inhibition role for adenovirus nucleic acid replication.

Preparation, characterisation and antimicrobial activities of polymer/realgar nanocomposites

Preparation and study of homogeneous nanoparticles (NPs) have been an important area of research in recent years. In this work, we describe a polymer-protected method for the preparation and formation of realgar nanocomposites with various average diameters. Two types of macromolecules were selected and their interactions with nanorealgar were studied by spectrometric methods. It is found that the starch has a significant effect on the formation and growth of homogeneous nanorealgar with an average diameter of 30 nm. In the case of using polyvinylpyrrolidone (PVP) as a protecting polymer, the realgar NP size is in the range of 20–80 nm, with an average value of 55 nm. The polymer-protected nanorealgar shows superior antimicrobial activity against Escherichia coli and Staphylococcus aureus, whereas the bulky realgar colloid formed in aqueous solution has much less antimicrobial activity. The antimicrobial activity followed the order As4S4–starch NPs > As4S4–PVP NPs > As4S4 NPs, which suggests small realgar NPs are more favourable.

Arsenic Sulphide As&lt;sub&gt;4&lt;/sub&gt;S&lt;sub&gt;4&lt;/sub&gt; Nanoparticles: Physico-Chemical Properties and Anticancer Effects

In this study, arsenic sulphide As4S4nanoparticles have been prepared, by high-energy wet milling, in the presence of sodium dodecylsulphate, which acts a surfactant. Solid state properties of the nanoparticles were characterised by XRD, Raman scattering, specific surface area and particle size distribution. Changes in surface areas of the particles, in the 0.2 - 5.4 m2g-1range, and nanosize distributions, in the 100 - 250 nm range, characterise the surface and morphological properties of nanorealgar. Raman scattering revealed various species in the milled sample that indicate a disproportionate reaction (3As4S4→ 4As2S3+ 4As) occurring as a consequence of milling. Anticancer effects, of the milled species, were confirmed for the human multiple myeloma U266 and OPM1 cell lines. Dissolution experiments in simulated gastric fluid show a possibility for the application of the realgar nanoparticles as an oral dose in future arsenic drug cancer treatments.

The medicinal use of realgar (As4S4) and its recent development as an anticancer agent

Arsenicals have been known as poisons and paradoxically as therapeutic agents. In the early 1970s, Chinese physicians from Harbin revived the medicinal use of arsenicals as anticancer agents. Notable success was observed in the treatment of acute promyelocytic leukemia (APL) with arsenic trioxide (ATO). The FDA approved ATO injection in the year 2000 for the treatment of APL. In contrast, the clinical use of the other arsenical, realgar (As₄S₄), is currently much less established, though it has also long been used in medical history. According to ancient medical records and recent findings in clinical trials, realgar was found as effective as ATO, but with relatively good oral safety profiles even on chronic administration. These give realgar an advantage over ATO in maintenance treatment. Though there is increasing understanding on the mechanisms of action and metabolic profiles of ATO, similar aspects of realgar are unclear to date. We outline the use of realgar in traditional medicines, especially in traditional Chinese medicines (TCM) from ancient times to present. The clinical and experimental observations on realgar as a therapeutic agent are described with an emphasis on those findings that may imply the rationale and future directions of realgar as a potential anticancer drug candidate. There is an increasing understanding in the mechanisms of action of realgar as an antileukemic agent. However, there is still sparse information on its metabolism and toxicity profiles. Realgar is poorly soluble in water. Recently, several types of realgar nanoparticles (NPs) have been developed. Some of these realgar NPs also possess the unique optical properties of quantum dots. The activities and bioavailability of realgar NPs are much influenced by their sizes, making realgar an interesting biomedical and pharmaceutical research candidate.

Effect of size and processing method on the cytotoxicity of realgar nanoparticles in cancer cell lines

In this study, the effects of the size and Chinese traditional processing (including elutriation, water cleaning, acid cleaning, alkali cleaning) on realgar nanoparticles (RN)-induced antitumor activity in human osteosarcoma cell lines (MG-63) and hepatoma carcinoma cell lines (HepG-2) were investigated. The human normal liver cell line (L-02) was used as control. RN was prepared by high-energy ball milling technology. The results showed that with the assistance of sodium dodecyl sulfate, the size of realgar could be reduced to 127 nm after 12 hours’ ball milling. The surface charge was decreased from 0.83 eV to −17.85 eV and the content of As2O3 clearly increased. Except for elutriation, the processing methods did not clearly change the size of the RN, but the content of As2O3 was reduced dramatically. In vitro MTT tests indicated that in the two cancer cell lines, RN cytotoxicity was more intense than that of the coarse realgar nanoparticles, and cytotoxicity was typically time- and concentration-dependent. Also, RN cytotoxicities in the HepG-2 and L-02 cells all increased with increasing milling time. Due to the reduction of the As2O3 content, water cleaning, acid cleaning, and alkali cleaning decreased RN cytotoxicity in HepG-2, but RN after elutriation, with the lowest As2O3 (3.5 mg/g) and the smallest size (109.3 nm), showed comparable cytotoxicity in HepG-2 to RN without treatment. Meanwhile, RN-induced cytotoxicity in L-02 cells was clearly reduced. Therefore, it can be concluded that RN may provide a strong antiproliferation effect in the MG-63 and HepG-2 cells. Elutriation processing is a suitable approach to limit the dangerous side-effects of As2O3, while maintaining the effectiveness of RN.

Preparation and characterization of realgar nanoparticles and their inhibitory effect on rat glioma cells

AimOur objective was to prepare a new nano-sized realgar particle and characterize its anti-tumor effect on tumor cells.MethodsNanoparticles were prepared by coprecipitation and were detected by transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometry (EDS), and dynamic light scattering. An anti-proliferative effect of realgar nanoparticles on rat glioma (C6) cells was determined by the MTT assay. Cell cycle and apoptosis rates were observed by flow cytometry. Apoptosis-related gene expression was detected by immunofluorescence staining.ResultsRealgar nanoparticles were successfully prepared. The particles were spherical, with an average diameter of approximately 80 nm, and contained arsenic and sulfur elements. Realgar nanoparticles inhibited C6 cell proliferation and induced apoptosis in a dose- and time-dependent manner. Treatment of C6 cells with realgar nanoparticles significantly increased the proportions of cells in S and G2/M phases, decreased the proportion of cells in G0/G1 phase, downregulated Bcl-2 expression, and substantially upregulated Bax expression.ConclusionRealgar nanoparticles significantly inhibited C6 glioma cell proliferation and promoted cell apoptosis by inducing the upregulation of Bax and downregulation of Bcl-2 expression. Realgar nanoparticles are a promising in vitro anti-cancer strategy and may be applicable for human cancer therapy studies.