In vitro toxicity assessment of oral nanocarriers

Synthesis of calix (4) resorcinarene based amphiphilic macrocycle as an efficient nanocarrier for Amphotericin-B to enhance its oral bioavailability

The supramolecular-based macrocyclic amphiphiles have fascinating attention and find extensive utilization in the pharmaceutical industry for efficient drug delivery. In this study, we designed and synthesized a new supramolecular amphiphilic macrocycle to serve as an efficient nanocarrier, achieved by treating 4-hydroxybenzaldehyde with 1-bromotetradecane. The derivatized product was subsequently treated with resorcinol to cyclize, resulting in the formation of a calix(4)-resorcinarene-based supramolecular amphiphilic macrocycle. The synthesized macrocycle and intermediate products were characterized using mass spectrometry, IR, and 1H NMR spectroscopic techniques. The amphotericin-B (Amph-B)-loaded and unloaded amphiphiles were screened for biocompatibility studies, vesicle formation, particle shape, size, surface charge, drug entrapment, in-vitro release profile, and stability through atomic force microscopy (AFM), Zetasizer, HPLC, and FT-IR. Amph-B -loaded macrocycle-based niosomal vesicles were investigated for in-vivo bioavailability in rabbits. The synthesized macrocycle exhibited no cytotoxicity against normal mouse fibroblast cells and was found to be hemocompatible and safe in mice following an acute toxicity study. The drug-loaded macrocycle-based vesicles appeared spherical, nano-sized, and homogeneous in size, with a notable negative surface charge. The vesicles remained stable after 30 days of storage. The results of Amph-B oral bioavailability and pharmacokinetics revealed that the newly tailored niosomal formulation enhanced drug solubility, protected drug degradation at gastric pH, facilitated sustained drug release at the specific target site, and delayed plasma drug clearance. Incorporating such advanced niosomal formulations in the field of drug delivery systems has the potential to revolutionize therapeutic outcomes and improve the quality of patient well-being.

Monophosphoryl lipid A-assembled nanovaccines enhance tumor immunotherapy

Therapeutic cancer nanovaccines can induce strong antitumor immunity and establish long-term immune memory and have shown potential for curing tumors in some clinical trials. However, weak immunogenicity and safety concerns of nanocarriers limit the clinical translation of some therapeutic nanovaccines. Here, we developed minimal-component cancer nanovaccines, monophosphoryl lipid A (MPLA)-assembled nanovaccines (MANs), that could facilitate the clinical application of nanovaccines. The MANs were formed by protein antigens extracted from chemotherapy-induced tumor cell cultures and the amphiphilic immune adjuvant MPLA. Compared with free chemotherapy-induced antigens, MANs can activate the Toll-like receptor 4 (TLR4)-mediated signalling pathway and promote adaptive immunity against tumor antigens. Mechanistic analysis indicated that MANs induced antigen capture of DCs and promoted the activation of DCs and T cells, thereby optimizing the ratio of CD8+ T/Tregs in tumors and facilitating the transformation of the tumor immune microenvironment (TIME) from "cold" to "hot". In a CT26 colorectal cancer model, MANs+αPD-1 significantly improved the efficacy of αPD-1 treatment. Our work offers a strategy for designing minimal-component cancer nanovaccines with potential clinical benefits. STATEMENT OF SIGNIFICANCE: To address the weak immunogenicity of cancer vaccines and the safety concerns of nanocarriers, we prepared MPLA-assembled nanovaccines (MANs) using chemotherapy induced antigens and the immune adjuvant MPLA to promote cancer vaccines to clinical practice. MANs effectively internalized tumor antigens and induced DC maturation, indicating that the initial anti-tumor response had been activated. MANs+αPD-1 induced APCs, CD8+ T cells and memory T cells with positive anti-tumor effects to migrate to tumor tissue, thus leading to the transformation of the tumor immune microenvironment from "cold" to "hot". At the animal level, the combination of MANs and αPD-1 exerted synergistic effects and significantly enhanced tumor immunotherapy. Therefore, the treatment regimen of MANs+αPD-1 has potential clinical benefits.

Biodegradable polyester-based nano drug delivery system in cancer chemotherapy: a review of recent progress (2021-2023)

Cancer presents a formidable threat to human health, with the majority of cases currently lacking a complete cure. Frequently, chemotherapy drugs are required to impede its progression. However, these drugs frequently suffer from drawbacks such as poor selectivity, limited water solubility, low bioavailability, and a propensity for causing organ toxicity. Consequently, a concerted effort has been made to seek improved drug delivery systems. Nano-drug delivery systems based on biodegradable polyesters have emerged as a subject of widespread interest in this pursuit. Extensive research has demonstrated their potential for offering high bioavailability, effective encapsulation, controlled release, and minimal toxicity. Notably, poly (ε-caprolactone) (PCL), poly (lactic-co-glycolic acid) (PLGA), and polylactic acid (PLA) have gained prominence as the most widely utilized options as carriers of the nano drug delivery system. This paper comprehensively reviews recent research on these materials as nano-carriers for delivering chemotherapeutic drugs, summarizing their latest advancements, acknowledging their limitations, and forecasting future research directions.

Research Progress of Nanomaterials in Chemotherapy of Osteosarcoma

Osteosarcoma (OS) is a common malignant bone tumor that occurs mostly in children and adolescents. At present, surgery after chemotherapy or postoperative adjuvant chemotherapy is the main treatment plan. However, the efficacy of chemotherapeutic drugs is limited by the occurrence of chemotherapeutic resistance, toxicity to normal cells, poor pharmacokinetic performance, and drug delivery failure. The delivery of chemotherapy drugs to the bone to treat OS may fail for a variety of reasons, such as a lack of selectivity for OS cells, initial sudden release, short-term release, and the presence of biological barriers (such as the blood-bone marrow barrier). Nanomaterials are new materials with at least one dimension on the nanometer scale (1-100 nm) in three-dimensional space. These materials have the ability to penetrate biological barriers and can accumulate preferentially in tumor cells. Studies have shown that the effective combination of nanomaterials and traditional chemotherapy can significantly improve the therapeutic effect. Therefore, this article reviews the latest research progress on the use of nanomaterials in OS chemotherapy.

The alamar blue assay in the context of safety testing of nanomaterials

The Alamar Blue (AB) assay is widely used to investigate cytotoxicity, cell proliferation and cellular metabolic activity within different fields of toxicology. The use of the assay with nanomaterials (NMs) entails specific aspects including the potential interference of NMs with the test. The procedure of the AB assay applied for testing NMs is described in detail and step-by-step, from NM preparation, cell exposure, inclusion of interference controls, to the analysis and interpretation of the results. Provided that the proper procedure is followed, and relevant controls are included, the AB assay is a reliable and high throughput test to evaluate the cytotoxicity/proliferation/metabolic response of cells exposed to NMs.

Nanocarrier Drug Delivery Systems: Characterization, Limitations, Future Perspectives and Implementation of Artificial Intelligence

There has been an increasing demand for the development of nanocarriers targeting multiple diseases with a broad range of properties. Due to their tiny size, giant surface area and feasible targetability, nanocarriers have optimized efficacy, decreased side effects and improved stability over conventional drug dosage forms. There are diverse types of nanocarriers that have been synthesized for drug delivery, including dendrimers, liposomes, solid lipid nanoparticles, polymersomes, polymer-drug conjugates, polymeric nanoparticles, peptide nanoparticles, micelles, nanoemulsions, nanospheres, nanocapsules, nanoshells, carbon nanotubes and gold nanoparticles, etc. Several characterization techniques have been proposed and used over the past few decades to control and predict the behavior of nanocarriers both in vitro and in vivo. In this review, we describe some fundamental in vitro, ex vivo, in situ and in vivo characterization methods for most nanocarriers, emphasizing their advantages and limitations, as well as the safety, regulatory and manufacturing aspects that hinder the transfer of nanocarriers from the laboratory to the clinic. Moreover, integration of artificial intelligence with nanotechnology, as well as the advantages and problems of artificial intelligence in the development and optimization of nanocarriers, are also discussed, along with future perspectives.

In vitro toxicological evaluation of mesoporous silica microparticles functionalised with carvacrol and thymol

The cytotoxicity of carvacrol- and thymol-functionalised mesoporous silica microparticles (MCM-41) was assessed in the human hepatocarcinoma cell line (HepG2). Cell viability, lactate dehydrogenase (LDH) activity, reactive oxygen species (ROS) production, mitochondrial membrane potential (ΔΨm), lipid peroxidation (LPO) and apoptosis/necrosis analyses were used as endpoints. The results showed that both materials induced cytotoxicity in a time- and concentration-dependent manner, and were more cytotoxic than free essential oil components and bare MCM-41. This effect was caused by cell-particle interactions and not by degradation products released to the culture media, as demonstrated in the extract dilution assays. LDH release was a less sensitive endpoint than the MTT (thiazolyl blue tetrazolium bromide) assay, which suggests the impairment of the mitochondrial function as the primary cytotoxic mechanism. In vitro tests on specialised cell functions showed that exposure to sublethal concentrations of these materials did not induce ROS formation during 2 h of exposure, but produced LPO and ΔΨm alterations in a concentration-dependent manner when cells were exposed for 24 h. The obtained results generally support the hypothesis that the carvacrol- and thymol-functionalised MCM-41 microparticles induced toxicity in HepG2 cells by an oxidative stress-related mechanism that resulted in apoptosis through the mitochondrial pathway.

Label-free cell based impedance measurements of ZnO nanoparticles-human lung cell interaction: a comparison with MTT, NR, Trypan blue and cloning efficiency assays

Background

There is a huge body of literature data on ZnOnanoparticles (ZnO NPs) toxicity. However, the reported results are seen to be increasingly discrepant, and deep comprehension of the ZnO NPs behaviour in relation to the different experimental conditions is still lacking. A recent literature overview emphasizes the screening of the ZnO NPs toxicity with more than one assay, checking the experimental reproducibility also versus time, which is a key factor for the robustness of the results. In this paper we compared high-throughput real-time measurements through Electric Cell-substrate Impedance-Sensing (ECIS®) with endpoint measurements of multiple independent assays.

Results

ECIS-measurements were compared with traditional cytotoxicity tests such as MTT, Neutral red, Trypan blue, and cloning efficiency assays. ECIS could follow the cell behavior continuously and noninvasively for days, so that certain long-term characteristics of cell proliferation under treatment with ZnO NPs were accessible. This was particularly important in the case of pro-mitogenic activity exerted by low-dose ZnO NPs, an effect not revealed by endpoint independent assays. This result opens new worrisome questions about the potential mitogenic activity exerted by ZnO NPs, or more generally by NPs, on transformed cells. Of importance, impedance curve trends (morphology) allowed to discriminate between different cell death mechanisms (apoptosis vs autophagy) in the absence of specific reagents, as confirmed by cell structural and functional studies by high-resolution microscopy. This could be advantageous in terms of costs and time spent. ZnO NPs-exposed A549 cells showed an unusual pattern of actin and tubulin distribution which might trigger mitotic aberrations leading to genomic instability.

Conclusions

ZnO NPs toxicity can be determined not only by the intrinsic NPs characteristics, but also by the external conditions like the experimental setting, and this could account for discrepant data from different assays. ECIS has the potential to recapitulate the needs required in the evaluation of nanomaterials by contributing to the reliability of cytotoxicity tests. Moreover, it can overcome some false results and discrepancies in the results obtained by endpoint measurements. Finally, we strongly recommend the comparison of cytotoxicity tests (ECIS, MTT, Trypan Blue, Cloning efficiency) with the ultrastructural cell pathology studies.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01033-w.

Characterization of an ester-based core-multishell (CMS) nanocarrier for the topical application at the oral mucosa

OBJECTIVES

Topical drug administration is commonly applied to control oral inflammation. However, it requires sufficient drug adherence and a high degree of bioavailability. Here, we tested the hypothesis whether an ester-based core-multishell (CMS) nanocarrier is a suitable nontoxic drug-delivery system that penetrates efficiently to oral mucosal tissues, and thereby, increase the bioavailability of topically applied drugs.

MATERIAL AND METHODS

To evaluate adhesion and penetration, the fluorescence-labeled CMS 10-E-15-350 nanocarrier was applied to ex vivo porcine masticatory and lining mucosa in a Franz cell diffusion assay and to an in vitro 3D model. In gingival epithelial cells, potential cytotoxicity and proliferative effects of the nanocarrier were determined by MTT and sulphorhodamine B assays, respectively. Transepithelial electrical resistance (TEER) was measured in presence and absence of CMS 10-E-15-350 using an Endohm-12 chamber and a volt-ohm-meter. Cellular nanocarrier uptake was analyzed by laser scanning microscopy. Inflammatory responses were determined by monitoring pro-inflammatory cytokines using real-time PCR and ELISA.

RESULTS

CMS nanocarrier adhered to mucosal tissues within 5 min in an in vitro model and in ex vivo porcine tissues. The CMS nanocarrier exhibited no cytotoxic effects and induced no inflammatory responses. Furthermore, the physical barrier expressed by the TEER remained unaffected by the nanocarrier.

CONCLUSIONS

CMS 10-E-15-350 adhered to the oral mucosa and adhesion increased over time which is a prerequisite for an efficient drug release. Since TEER is unaffected, CMS nanocarrier may enter the oral mucosa transcellularly.

CLINICAL RELEVANCE

Nanocarrier technology is a novel and innovative approach for efficient topical drug delivery at the oral mucosa.

Nanonutraceuticals: The New Frontier of Supplementary Food

In the last few decades, the combination between nanotechnology and nutraceutics has gained the attention of several research groups. Nutraceuticals are considered as active compounds, abundant in natural products, showing beneficial effects on human health. Unfortunately, the uses, and consequently the health benefits, of many nutraceutical products are limited by their unsuitable chemico-physical features. For example, many nutraceuticals are characterized by low water solubility, low stability and high susceptibility to light and oxygen, poor absorption and potential chemical modifications after their administration. Based on the potential efficacy of nutraceuticals and on their limiting features, nanotechnology could be considered a revolutionary innovation in empowering the beneficial properties of nutraceuticals on human health, thus enhancing their efficacy in several diseases. For this reason, nanotechnology could represent a new frontier in supplementary food. In this review, the most recent nanotechnological approaches are discussed, focusing on their ability to improve the bioavailability of the most common nutraceuticals, providing an overview regarding both the advantages and the possible limitations of the use of several nanodelivery systems. In fact, although the efficacy of smart nanocarriers in improving health benefits deriving from nutraceuticals has been widely demonstrated, the conflicting opinions on the mechanism of action of some nanosystems still reduce their applicability in the therapeutic field.

Targeted Dual Small Interfering Ribonucleic Acid Delivery via Non-Viral Polymeric Vectors for Pulmonary Fibrosis Therapy

Inhibiting the myofibroblast differentiation of lung-resident mesenchymal stem cells (LR-MSCs) is a promising yet challenging approach for pulmonary fibrosis (PF) therapy. Here, micelles formed by a graft copolymer of multiple PEGs modified branched polyethylenimine are used for delivering runt-related transcription factor-1 (RUNX1) small interfering RNA (siRNA) (siRUNX1) to the lung, aiming to inhibit the myofibroblast differentiation of LR-MSCs. LR-MSC targeting is achieved by functionalizing the micelle surface with an anti-stem-cell antigen-1 antibody fragment (Fab'). Consequently, therapeutic benefits are obtained by successful suppression of myofibroblast differentiation of LR-MSCs in bleomycin-induced PF model mice treated with siRUNX1-loaded micelles. Furthermore, an excellent synergistic effect of PF therapy is achieved for this micelle system loaded siRUNX1 and glioma-associated oncogene homolog-1 (Gli1) small interfering RNA (siGli1), a traditional anti-PF siRNA of glioma-associated oncogene homolog-1. Hence, this work not only provides RUNX1 as a novel PF therapeutic target, but also as a promising dual siRNA-loaded nanocarrier system for the therapy of PF.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

In Vitro and In Vivo Models for Evaluating the Oral Toxicity of Nanomedicines

Toxicity studies for conventional oral drug formulations are standardized and well documented, as required by the guidelines of administrative agencies such as the US Food & Drug Administration (FDA), the European Medicines Agency (EMA) or European Medicines Evaluation Agency (EMEA), and the Japanese Pharmaceuticals and Medical Devices Agency (PMDA). Researchers tend to extrapolate these standardized protocols to evaluate nanoformulations (NFs) because standard nanotoxicity protocols are still lacking in nonclinical studies for testing orally delivered NFs. However, such strategies have generated many inconsistent results because they do not account for the specific physicochemical properties of nanomedicines. Due to their tiny size, accumulated surface charge and tension, sizeable surface-area-to-volume ratio, and high chemical/structural complexity, orally delivered NFs may generate severe topical toxicities to the gastrointestinal tract and metabolic organs, including the liver and kidney. Such toxicities involve immune responses that reflect different mechanisms than those triggered by conventional formulations. Herein, we briefly analyze the potential oral toxicity mechanisms of NFs and describe recently reported in vitro and in vivo models that attempt to address the specific oral toxicity of nanomedicines. We also discuss approaches that may be used to develop nontoxic NFs for oral drug delivery.

Enhancing the Furosemide Permeability by Papain Minitablets Through a Triple Co-culture In Vitro Intestinal Cell Model

The administration of medicines by the oral route is the most used approach for being very convenient. Although it is the most popular, this route also has absorption, and consequently, bioavailability limitations. In this sense, several pharmacotechnical strategies have been used to improve drug absorption, one of which is the use of permeation promoters. Papain is a very versatile plant enzyme that can be used as a permeation promoter of various active compounds. This study aimed to evaluate the safety of papain and the formulation of native papain minitablets to promote in vitro permeation of furosemide through an innovative biomimetic triple co-culture model of Caco-2, HT29-MTX, and Raji cells. Regarding permeation, furosemide and metaprolol concentrations are determined with HPLC; those are used to calculate P_app. Monolayer integrity was evaluated using TEER and Lucifer Yellow. In the presence of papain, TEER decreased two-fold and the P_app of furosemide increased six-fold. The results suggest that native papain minitablets can be used as therapeutic adjuvants to enhance the permeation of drugs significantly improving bioavailability.

Recent Advances in Nanocarrier-Assisted Therapeutics Delivery Systems

Nanotechnologies have attracted increasing attention in their application in medicine, especially in the development of new drug delivery systems. With the help of nano-sized carriers, drugs can reach specific diseased areas, prolonging therapeutic efficacy while decreasing undesired side-effects. In addition, recent nanotechnological advances, such as surface stabilization and stimuli-responsive functionalization have also significantly improved the targeting capacity and therapeutic efficacy of the nanocarrier assisted drug delivery system. In this review, we evaluate recent advances in the development of different nanocarriers and their applications in therapeutics delivery.

Validation of an Ex Vivo Permeation Method for the Intestinal Permeability of Different BCS Drugs and Its Correlation with Caco-2 In Vitro Experiments

The absorption study of drugs through different biological membranes constitutes an essential step in the development of new pharmaceutical dosage forms. Concerning orally administered forms, methods based on monolayer cell culture of Caco-2 (Caucasian colon adenocarcinoma) have been developed to emulate intestinal mucosa in permeability studies. Although it is widely accepted, it has disadvantages, such as high costs or high technical complexity, and limitations related to the simplified structure of the monolayer or the class of molecules that can be permeated according to the transport mechanisms. The aim of this work was to develop a new ex vivo methodology which allows the evaluation of the intestinal apparent permeability coefficient (P_app) while using fewer resources and to assess the correlation with Caco-2. To this end, pig (Sus scrofa) duodenum segments were mounted in Franz diffusion cells and used to permeate four different drugs: ketorolac tromethamine (Kt), melatonin (Mel), hydrochlorothiazide (Htz), and furosemide (Fur). No statistically significant differences (p > 0.05) were observed corelating P_app values from Franz diffusion cells and Caco-2 cell experiments for Kt, Htz, and Fur. However, there were statistically significant differences (p < 0.05) correlating P_app values and Mel. The difference is explained by the role of Mel in the duodenal epithelial paracellular permeability reduction. Ex vivo permeation may be an equivalent method to Caco-2 for drugs that do not produce intestinal membrane phenomena that could affect absorption.

β-carotene and α-tocopherol coencapsulated in nanostructured lipid carriers of murumuru (Astrocaryum murumuru) butter produced by phase inversion temperature method: characterisation, dynamic in vitro digestion and cell viability study

Hydrophobic bioactives can be more easily incorporated into food and have their bioavailability enhanced if nanostructured lipid carriers (NLC) are used as carriers. In the present study, beta-carotene-loaded NLC were produced by low emulsification using murumuru butter and a mixture of Span 80 and Cremophor RH40 as surfactants. Their average diameter was 35 nm and alpha-tocopherol was required to protect the encapsulated β-carotene. Besides the evaluation of their physicochemical stability, NLC were submitted to dynamic in vitro digestion and cell viability assays with Caco-2 and HEPG cells. The bioaccessibility of beta-carotene in the dynamic system was about 42%. Regarding cell viability, results indicated NLC were toxic to the cell cultures tested. Such high toxicity is probably related to the type of surfactant used and to the extremely reduced particle size, which may have led to an intense and fast permeation of the NLC through the cells.

Biocompatibility studies of intravenously administered ionic-crosslinked chitosan-BSA nanoparticles as vehicles for antitumour drugs

In this study, a new alternative of ionic crosslinked nanoparticles (NPs) based on chitosan (C) and bovine serum albumin (A; BSA) was evaluated as drug delivery system for antitumour compounds (doxorubicin hydrochloride as a model). The different responses to the pH of the medium were determined by the electrostatic interactions induced by each polymeric combination (C50/A50; C80/A20; C20/A80). NPs revealed a nanoscale size (167-392 nm) and a positive net charge (12-26 mV), modulated by doxorubicin (DOX) loading. Drug loading capacity was higher than 5.2 ± 1.8 μgDOX/mgNP (Encapsulation efficiency = 34%), and an initial burst release was followed by a sustained delivery. Cellular uptake assays confirmed the entry of NPs in three human tumor cells (MCF7, T47D and Hela), triggering antioxidant responses (superoxide dismutase, catalase, glutathione reductase and total glutathione content) in those cells. This was also consistent with the decreased in IC50 values observed after the incubation of these cells with C20/A80-DOX and C50/A50-DOX NPs (1.90-3.48 μg/mL) compared with free DOX (2.36-6.025 μg/mL). In vivo results suggested that the selected proportions of chitosan-BSA created nonhemolytic and biocompatible stable NPs at the selected dose of 20 mg/kg. Despite the different formulations, this study demonstrated that these NPs could serve as safe drug carriers in further in vivo investigations.

Stable PEG-coated silver nanoparticles - A comprehensive toxicological profile

The present study was purported to assess the toxicological profile of bare and polyethylene glycol (PEG) coated spherical silver nanoparticles (AgNPs) by means of in vitro (on human keratinocytes - HaCat cells) and in vivo non-invasive tests (after intraperitoneal - i.p. administration to mice). Bare and PEG-coated AgNPs were synthesized by applying Turkevich's method slightly modified. The physico-chemical characterization revealed the formation of stable, spherical AgNPs and PEG-AgNPs, with narrow size distributions and mean hydrodynamic sizes in the range of 19 nm and 50 nm, respectively. Toxicity data revealed a dose-dependent safe profile for low concentrations of test compounds (<10 μM) in terms of cell viability, whereas higher concentrations were associated with a high rate of cell mortality. In vivo acute/subacute toxicity data showed no denotive changes in mice health status after i.p. administration. Histological observations of internal organs and the biochemical parameters analyzed together with the other biological observations showed a low toxicity level with no major differences related to control, albeit at skin level a reduced number of mast cells was detected. All these observations provide strong support for the idea that coated silver nanoparticles could be applied as targeted nanocarriers for skin pathologies and diagnostic.

In Vitro Toxicity Testing of Food Contact Materials: State-of-the-Art and Future Challenges

Currently, toxicological testing of food contact materials (FCMs) is focused on single substances and their genotoxicity. However, people are exposed to mixtures of chemicals migrating from food contact articles (FCAs) into food, and toxic effects other than genotoxic damage may also be relevant. Since FCMs can be made of more than 8 thousand substances, assessing them one-by-one is very resource-consuming. Moreover, finished FCAs usually contain non-intentionally added substances (NIAS). NIAS toxicity can only be tested if a substance's chemical identity is known and if it is available as a pure chemical. Often, this is not the case. Nonetheless, regulations require safety assessments for all substances migrating from FCAs, including NIAS, hence new approaches to meet this legal obligation are needed. Testing the overall migrate or extract from an FCM/FCA is an option. Ideally, such an assessment would be performed by means of in vitro bioassays, as they are rapid and cost-effective. Here, we review the studies using in vitro bioassays to test toxicity of FCMs/FCAs. Three main categories of in vitro assays that have been applied include assays for cytotoxicity, genotoxicity, and endocrine disruption potential. In addition, we reviewed studies with small multicellular animal-based bioassays. Our overview shows that in vitro testing of FCMs is in principle feasible. We discuss future research needs and FCM-specific challenges. Sample preparation procedures need to be optimized and standardized. Further, the array of in vitro tests should be expanded to include those of highest relevance for the most prevalent human diseases of concern.

Phytochemical Characterization and Biological Evaluation of the Aqueous and Supercritical Fluid Extracts from Salvia sclareoides Brot

Plants belonging to the genus Salvia (Lamiaceae) are known to have a wide range of biological properties. In this work, extracts obtained from the aerial parts of Salvia sclareoides Brot. were evaluated to investigate their chemical composition, toxicity, bioactivity, and stability under in vitro gastrointestinal conditions. The composition of the supercritical fluid extract was determined by GC and GC-MS, while the identification of the infusion constituents was performed by HPLC-DAD and LC-MS. The in vitro cytotoxicity of both extracts (0-2 mg/mL) was evaluated in Caco-2 cell lines by the MTT assay. The anti-inflammatory and anticholinesterase activities were determined through the inhibition of cyclooxygenase-1 and acetylcholinesterase enzymes, while β-carotene/linoleic acid bleaching test and the DPPH assays were used to evaluate the antioxidant activity. The infusion inhibited cyclooxygenase-1 (IC50 = 271.0 μg/mL), and acetylcholinesterase (IC50 = 487.7 μg/ mL) enzymes, also demonstrated significant antioxidant properties, as evaluated by the DPPH (IC50 = 10.4 μg/mL) and β-carotene/linoleic acid (IC50 = 30.0 μg/mL) assays. No remarkable alterations in the composition or in the bioactivities of the infusion were observed after in vitro digestion, which supports the potential of S. sclareoides as a source of bioactive ingredients with neuroprotective, anti-inflammatory and antioxidant properties.