Subacute feeding toxicity of low-sodium sausages manufactured with sodium substitutes and biopolymer-encapsulated saltwort (Salicornia herbacea) in a mouse model.

BACKGROUND: Low-sodium sausages were manufactured using sodium substitution and biopolymer encapsulation. A diet comprising 10% treatment sausages (six treatment groups: C (100% NaCl), T1 (55% sodium substitute + 45% saltwort salt), T2 (55% sodium substitute + 45% saltwort salt with chitosan), T3 (55% sodium substitute + 45% saltwort salt with cellulose), T4 (55% sodium substitute + 45% saltwort salt with dextrin), and T5 (55% sodium substitute + 45% saltwort salt with pectin)) was added to a 90% commercial mouse diet for 4 weeks. RESULTS: Subacute toxicity, hematology, liver function, and organ weight tests in low-sodium sausage groups showed results similar to those of the control group, and all toxicity test levels were within normal ranges. CONCLUSIONS: All low-sodium sausage types tested are suggested to be safe in terms of subacute toxicity. Moreover, low-sodium sausages can be manufactured by biopolymer encapsulation of saltwort using pectin, chitosan, cellulose, and dextrin without toxicity. © 2019 Society of Chemical Industry.

Characterization and toxicity of a phosphate-binding exobiopolymer produced by Acinetobacter haemolyticus MG606.

A novel, phosphate-binding exobiopolymer (EBP) produced by Acinetobacter haemolyticus MG606 was characterized and its biocompatibility evaluated in RAW 264.7 cells and in mice. EBP was identified as a 50 kDa heteropolysaccharide composed of pentose and hexose sugars. EBP exhibited cytotoxicity, stimulation of free radical production and loss of mitochondrial and lysosomal integrity in RAW 264.7 cells at 500 µg/mL concentration while lower concentrations exhibited no significant (p > 0.05) effect on these parameters. EBP exhibited dose-dependent mortality, body weight reduction, hypothermia and clinical signs of toxicity in mice following intraperitoneal administration. The LD50 of EBP was determined to be 92.31 mg/kg. Overall, the results of our study suggest that composition of EBP produced by A. haemolyticus MG606 is distinct from EBP produced by other Acinetobacter spp. The high biocompatibility supports application of EBP as a safe biosorbent for phosphate remediation.

Safety Assessment of Microbial Polysaccharide Gums as Used in Cosmetics.

The Cosmetic Ingredient Review Expert Panel assessed the safety of 34 microbial polysaccharide gums for use in cosmetics, finding that these ingredients are safe in cosmetic formulations in the present practices of use and concentration. The microbial polysaccharide gums named in this report have a variety of reported functions in cosmetics, including emulsion stabilizer, film former, binder, viscosity-increasing agent, and skin-conditioning agent. The Panel reviewed available animal and clinical data in making its determination of safety.

Extracellular Polymeric Substances of Aphanizomenon flos-aquae (EPS-A) Induced Apoptosis in Astrocytes of Zebrafish.

In this study, extracellular polymeric substances of Aphanizomenon flos-aquae (EPS-A) were investigated in order to explore their effect on astrocytes of zebrafish and potential risk for environment. Astrocytes were treated with varying concentrations of EPS-A, the results showed that EPS-A inhibited astrocytes growth in a dose-and time-dependent manner. With the concentrations of EPS-A increasing, the adherent ability of astrocytes decreased and the number of astrocytes floating in the culture medium increased. When treated with 2.35 µg/mL EPS-A, EPS-A induced cell cycle arrest and made the collapse of mitochondrial membrane potential and then led to astrocytes apoptosis. The results suggested that EPS-A could pose a threat to zebrafish and represent risk for environment, so regularly monitoring the presence of EPS-A was very important in nutrient-rich freshwaters when A. flos-aquae blooms broke out.

How epigallocatechin gallate can inhibit α-synuclein oligomer toxicity in vitro.

Oligomeric species of various proteins are linked to the pathogenesis of different neurodegenerative disorders. Consequently, there is intense focus on the discovery of novel inhibitors, e.g. small molecules and antibodies, to inhibit the formation and block the toxicity of oligomers. In Parkinson disease, the protein α-synuclein (αSN) forms cytotoxic oligomers. The flavonoid epigallocatechin gallate (EGCG) has previously been shown to redirect the aggregation of αSN monomers and remodel αSN amyloid fibrils into disordered oligomers. Here, we dissect EGCG's mechanism of action. EGCG inhibits the ability of preformed oligomers to permeabilize vesicles and induce cytotoxicity in a rat brain cell line. However, EGCG does not affect oligomer size distribution or secondary structure. Rather, EGCG immobilizes the C-terminal region and moderately reduces the degree of binding of oligomers to membranes. We interpret our data to mean that the oligomer acts by destabilizing the membrane rather than by direct pore formation. This suggests that reduction (but not complete abolition) of the membrane affinity of the oligomer is sufficient to prevent cytotoxicity.

Antimicrobial efficacy and in vivo toxicity studies of a quaternized biopolymeric flocculant.

This study evaluated the antibacterial spectrum and safety of a chemically modified biopolymeric flocculant (TMB) against waterborne pathogens. The biopolymer previously characterized as polysaccharide with flocculating activity is produced extracellularly by the bacterium Klebsiella terrigena. The amino sugars on the polymer were chemically modified by quaternization, which resulted in N,N,N trimethyl biopolymer (TMB). Quaternization was effective in imparting biocidal activity to TMB against five selected waterborne pathogens, namely, Aeromonas hydrophila, Yersinia enterocolitica, Salmonella typhimurium, Listeria monocytogenes and Escherichia coli O157:H7. 99.999% inactivation was achieved with S. typhimurium at a dose of 60 µg ml(-1) of TMB within 60 min at the ambient temperature, followed by other pathogens. Haemotological, histopathological and general examinations indicated no adverse effects in Swiss albino mice fed with the quaternized biopolymer (120 mg kg(-1) body weight(-1) day(-1)) over a period of 30 days. These results suggested that TMB was tolerated well without any signs of toxicity and may have potential application as a safe, antimicrobial bioflocculant for both removing and inactivating waterborne pathogens.

In vivo demonstration that alpha-synuclein oligomers are toxic.

The aggregation of proteins into oligomers and amyloid fibrils is characteristic of several neurodegenerative diseases, including Parkinson disease (PD). In PD, the process of aggregation of α-synuclein (α-syn) from monomers, via oligomeric intermediates, into amyloid fibrils is considered the disease-causative toxic mechanism. We developed α-syn mutants that promote oligomer or fibril formation and tested the toxicity of these mutants by using a rat lentivirus system to investigate loss of dopaminergic neurons in the substantia nigra. The most severe dopaminergic loss in the substantia nigra is observed in animals with the α-syn variants that form oligomers (i.e., E57K and E35K), whereas the α-syn variants that form fibrils very quickly are less toxic. We show that α-syn oligomers are toxic in vivo and that α-syn oligomers might interact with and potentially disrupt membranes.

Development of a biopolymer nanoparticle-based method of oral toxicity testing in aquatic invertebrates.

Aquatic toxicity testing generally focuses on the water absorption/dermal route of exposure to potential toxic chemicals, while much less work has been done on the oral route of exposure. This is due in part to the difficulties of applying traditional oral toxicity testing to aquatic environments, including the tendency for test chemicals to dissolve into water. The use of biopolymer nanoparticles to encapsulate test chemicals onto food to prevent dissolution is one solution presented herein. The biopolymers zein and chitosan were explored for their previously known nanoparticle-forming abilities. Nanoparticles containing the test chemical rhodamine B were formed, applied as films to coat food, and then fed to the test organism, the freshwater amphipod Hyalella azteca. In feeding trials both zein and chitosan nanoparticles showed a significantly lower release rate of rhodamine B into water than food dyed with rhodamine B without biopolymer nanoparticles. Zein nanoparticles also showed better retention ability than chitosan nanoparticles. Both kinds of nanoparticles showed no significant effect on the survival, growth, or feeding behavior of H. azteca. Thus these biopolymers may be an effective system to encapsulate and deliver chemicals to aquatic invertebrates without interfering with common toxicity assessment endpoints like survival and growth.

Assessment of respiration activity and ecotoxicity of composts containing biopolymers.

The research was conducted to determine if introducing biodegradable polymer materials to the composting process would affect selected biological properties of mature compost. Determination of biological properties of composts composed of testing their respiration activity and toxicity. Respiration activity was measured in material from the composting process by means of OxiTop Control measuring system. The ecotoxicity of composts was estimated by means of a set of biotests composed of three microbiotests using five test organisms. Introduction of polymer materials caused a decrease in respiration activity of mature compost. Similar dependencies as in the case of mass loss were registered. Compost to which a biodegradable polymer with the highest content of starch was added revealed the smallest difference in comparison with organic material composted without polymers. Lower content of starch in a polymer caused lower respiration activity of composts, whereas microorganism vaccine might have accelerated maturing of composts, thus contributing to the smallest respiration of compost. In composts containing biopolymers the following were observed: an increase in germination inhibition--2.5 times, roots growth inhibition--1.8 times, growth inhibition of Heterocypris incongruens--four times and luminescence inhibition of Vibrio fischeri--1.6 times in comparison with the control (compost K1). Composts containing biopolymers were classified as toxicity class III, whereas the compost without polymer addition as class II.

Effects of petroleum-based and biopolymer-based nanoplastics on aquatic organisms: A case study with mechanically degraded pristine polymers.

Mismanaged plastic litter submitted to environmental conditions may breakdown into smaller fragments, eventually reaching nano-scale particles (nanoplastics, NPLs). In this study, pristine beads of four different types of polymers, three oil-based (polypropylene, PP; polystyrene, PS; and low-density polyethylene, LDPE) and one bio-based (polylactic acid, PLA) were mechanically broken down to obtain more environmentally realistic NPLs and its toxicity to two freshwater secondary consumers was assessed. Thus, effects on the cnidarian Hydra viridissima (mortality, morphology, regeneration ability, and feeding behavior) and the fish Danio rerio (mortality, morphological alterations, and swimming behavior) were tested at NPLs concentrations in the 0.001 to 100 mg/L range. Mortality and several morphological alterations were observed on hydras exposed to 10 and 100 mg/L PP and 100 mg/L LDPE, whilst regeneration capacity was overall accelerated. The locomotory activity of D. rerio larvae was affected by NPLs (decreased swimming time, distance or turning frequency) at environmentally realistic concentrations (as low as 0.001 mg/L). Overall, petroleum- and bio-based NPLs elicited pernicious effects on tested model organisms, especially PP, LDPE and PLA. Data allowed the estimation of NPLs effective concentrations and showed that biopolymers may also induce relevant toxic effects.

Helicoverpa armigera cadherin fragment enhances Cry1Ac insecticidal activity by facilitating toxin-oligomer formation.

The interaction between Bacillus thuringiensis insecticidal crystal protein Cry1A and cadherin receptors in lepidopteran insects induces toxin oligomerization, which is essential for membrane insertion and mediates Cry1A toxicity. It has been reported that Manduca sexta cadherin fragment CR12-MPED and Anopheles gambiae cadherin fragment CR11-MPED enhance the insecticidal activity of Cry1Ab and Cry4Ba to certain lepidopteran and dipteran larvae species, respectively. This study reports that a Helicoverpa armigera cadherin fragment (HaCad1) containing its toxin binding region, expressed in Escherichia coli, enhanced Cry1Ac activity against H. armigera larvae. A binding assay showed that HaCad1 was able to bind to Cry1Ac in vitro and that this event did not block toxin binding to the brush border membrane microvilli prepared from H. armigera. When the residues (1423)GVLSLNFQ(1430) were deleted from the fragment, the subsequent mutation peptide lost its ability to bind Cry1Ac and the toxicity enhancement was also significantly reduced. Oligomerization tests showed that HaCad1 facilitates the formation of a 250-kDa oligomer of Cry1Ac-activated toxin in the midgut fluid environment. Oligomer formation was dependent upon the toxin binding to HaCad1, which was also necessary for the HaCad1-mediated enhancement effect. Our discovery reveals a novel strategy to enhance insecticidal activity or to overcome the resistance of insects to B. thuringiensis toxin-based biopesticides and transgenic crops.

Metal and anion composition of two biopolymeric chemical stabilizers and toxicity risk implication for the environment.

The objective of this study was to (1) measure the concentration of four anions (Cl(-), F(-), [image omitted], and [image omitted]) and nine other elements (Al, Ba, Ca, K, Mg, Mn, Fe, Ni, and Si) in two nontraditional biopolymeric chemical stabilizers (EBCS1 and EBCS2), (2) investigate consequent environmental toxicity risk implications, and (3) create awareness regarding environmental health issues associated with metal concentration levels in enzyme-based chemical stabilizers that are now gaining widespread application in road construction and other concrete materials. Potential ecotoxicity impacts were studied on aqueous extracts of EBCS1 and EBCS2 using two thermodynamic properties models: the Pitzer-Mayorga model (calculation of the electrolyte activity coefficients) and the Millero-Pitzer model (calculation of the ionic activity coefficients). Results showed not only high concentrations of a variety of metal ions and inorganic anions, but also a significant variation between two chemical stabilizing mixtures. The mixture (EBCS2) with the lower pH value was richer in all the cationic and anionic species than (EBCS1). Sulfate (SO(2-)(4)) concentrations were found to be higher in EBCS2 than in EBCS1. There was no correlation between electrolyte activity and presence of the ionic species, which may be linked to a possible high ionic environmental activity. The concentrations of trace metals found (Mn, Fe, and Ni) were low compared to those of earth metals (Ba, Ca, K, and Mg). The metal concentrations were higher in EBCS1 than in EBCS2. Data suggest that specific studies are needed to establish "zero" permissible metal ecotoxicity values for elements and anions in any such strong polyelectrolytic enzyme-based chemical stabilizers.

In-vitro degradation and toxicological assessment of pulsed electric fields crosslinked zein-chitosan-poly(vinyl alcohol) biopolymeric films.

We investigated the in vitro degradation and cytotoxic effects of edible films developed from pulsed electric fields (PEF) treated zein-chitosan-poly(vinyl alcohol) dispersions at specific energy 60-70, 385-400, and 620-650 kJ/kg. The degradation was evaluated using both simulated gastro-intestinal electrolyte solutions (SGES) and enzyme hydrolysis. The results of ortho-phthaldialdehyde (OPA) test indicated that the chemical breakdown of the films in SGES and enzyme increased with degradation time, but the product's features were unmodified. The Fourier Transform Infrared spectroscopy (FTIR) data showed enhancement of zein and chitosan transformation from ordered helices to ß-sheet conformation. Relative cell survival rates of Hepa-1c1c7 cells investigated using 3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) showed that the survival remained higher than 70% in both the supernatant and the residue of the SGES degraded samples and the supernatant from enzyme hydrolysis, which suggested that there was no significant toxicity of the films in the tested system. Although the residue from pancreatic digestion (240 min) (i.e. undigested films and a cocktail of digestion enzymes) expressed cytotoxicity activity, there was limited evidence of direct toxicity of the films. The findings of the study demonstrate the potential for PEF modified zein-chitosan-poly(vinyl alcohol) films as value-added biomaterials for the application in edible food packaging.

Maysin plays a protective role against α-Synuclein oligomers cytotoxicity by triggering autophagy activation.

Parkinson's disease (PD) is a widespread neurodegenerative disorder characterized by the progressive loss of neurons. The accumulation of aggregated forms of the α-Synuclein (Syn) protein is the main cause of neurotoxicity in PD by disrupting cellular homeostasis until neuronal death. Scientific research is constantly looking for natural products as preventive agents against the progression of several neurodisorders due their safety and non-toxic nature. Neuroprotective phytochemicals include Maysin (Mys), the most abundant C-glycosilflavone in corn silk. In this work, the Mys protective role against damage by Syn amyloid aggregates - oligomers and fibrils - was investigated in SH-SY5Y human neuroblastoma cells obtaining novel and interesting information concerning the Mys molecular mechanism of action. Mys showed effectiveness in preventing the typical toxic events induced by Syn amyloid aggregates, i.e. oxidative stress and imbalance of intracellular calcium homeostasis. Mys exhibited a cytoprotective role, especially against Syn oligomers injury, activating an autophagic degradative process, thus playing a key role on several features of amyloid neurotoxicity. Therefore, Mys could be proposed for the first time to the scientific community as an interesting novel natural compound that might allow to develop alternative strategies to prevent the damage of Syn oligomers involved in Parkinson's disease.

De novo design of saccharide-peptide hydrogels as synthetic scaffolds for tailored cell responses.

A new class of functional saccharide-peptide copolymer-based hydrogels was synthesized and investigated as synthetic extracellular matrices for regenerative medicine applications. The polymer was composed entirely of natural building blocks, namely, galactaric acid and lysine on the backbone, with tyrosine grafted onto the side chain as a handle for enzyme-catalyzed hydrogelation. The resulting hydrogels are degradable under simulated physiological conditions and exhibit minimal cytotoxicity on dermal fibroblast and PC-12 cells. As a demonstration of the versatility of the system, the mechanical properties of the gels can be independently controlled without changing the polymer chemical composition. Using an identical copolymer solution, by simply allowing different lengths of cross-linking time, a series of hydrogels was obtained with different mechanical moduli at constant chemical structure. The moduli of the resulting hydrogels varied stepwise from 1.7, 4.1, 6.9, and 12.5 kPa to allow for systematic studies on the effects of modulus on cell behavior. It was exciting to observe that a simple change in hydrogel physical properties could induce a direct phenotypic change in cell adhesion and proliferation. Depending on the substrate mechanical modulus, the cell morphology changed and proliferation rate differed by an order of magnitude for different cell lines. These data suggest our saccharide-peptide hydrogels as promising synthetic extracellular matrices for cell culture and tissue regeneration.

Probing the Origin of the Toxicity of Oligomeric Aggregates of α-Synuclein with Antibodies.

The aggregation of α-synuclein, a protein involved in neurotransmitter release at presynaptic terminals, is associated with a range of highly debilitating neurodegenerative conditions, most notably Parkinson's disease. Intraneuronal inclusion bodies, primarily composed of α-synuclein fibrils, are the major histopathological hallmarks of these disorders, although small oligomeric assemblies are believed to play a crucial role in neuronal impairment. We have probed the mechanism of neurotoxicity of α-synuclein oligomers isolated in vitro using antibodies targeting the N-terminal region of the protein and found that the presence of the antibody resulted in a substantial reduction of the damage induced by the aggregates when incubated with primary cortical neurons and neuroblastoma cells. We observed a similar behavior in vivo using a strain of C. elegans overexpressing α-synuclein, where the aggregation process itself is also partially inhibited as a result of incubation with the antibodies. The similar effects of the antibodies in reducing the toxicity of the aggregated species formed in vitro and in vivo provide evidence for a common origin of cellular impairment induced by α-synuclein aggregates.

Extracellular biopolymers produced by Dictyosphaerium family - Chemical and immunomodulative properties.

Many microalgal species produce a wide range of highly-value products which are interesting for biotechnological applications. Cultivation of microalgal species Dictyosphaerium pulchellum and Dictyosphaerium tetrachotomum, strains Ruzicka and Fott resulted yields of 0.2, 0.7 and 1.8 g/L of extracellular biopolymers (EPSs), respectively. All biopolymers were shown to be anionic proteoglycans. The sugar composition analyses of all EPSs showed high contents of hexoses and the presence of partially methylated monosaccharide residues, i.e. hexoses, and deoxy hexoses. The dominant sugar component of all EPSs was found to be galactose. Extracellular microalgal biopolymers were subjected to immunobiological and immunotoxicological evaluation using murine melanoma cancer cells B16, murine fibroblast cell line NIH-3T3, murine macrophages cell line RAW 264.7 and skin construct EpiDerm™ (EPI-200). The EPSs exerted the antiproliferative effectivity; treatment of EPS induced proinflammatory cytokines TNF-α, IL-6, IL-12, IL-1ß and IL-17, also engaged in anti-cancer immunity. Immunotoxicological studies revealed their non-toxic character and safe application on EpiDerm™.

Amyloid beta interacts with the amyloid precursor protein: a potential toxic mechanism in Alzheimer's disease.

Amyloid beta protein (Abeta) deposition in the brain is a hallmark of Alzheimer's disease (AD). The fibrillar form of Abeta is neurotoxic, although the mechanism of its toxicity is unknown. We showed that conversion of Abeta to the fibrillar form markedly increased binding to specific neuronal membrane proteins, including amyloid precursor protein (APP). Nanomolar concentrations of fibrillar Abeta bound cell-surface holo-APP in cortical neurons. Reduced vulnerability of cultured APP-null neurons to Abeta neurotoxicity suggested that Abeta neurotoxicity involves APP. Thus Abeta toxicity may be mediated by the interaction of fibrillar Abeta with neuronal membrane proteins, notably APP. An Abeta-APP interaction reminiscent of the pathogenic mechanism of prions may thus contribute to neuronal degeneration in AD.

Sustainable Production of Fine Chemicals and Materials Using Nontoxic Renewable Sources.

Due to declining hydrocarbon resources and strengthening environmental regulations, significant attention is directed toward sustainable and nontoxic supplies for the development of green technologies in a variety of industries. This account provides an overview on the sources and recent applications of such materials surveying the most common nontoxic and renewable resources that can be obtained from biological sources. Developing a broad array of technologies based on these materials would establish a truly sustainable green chemical industry. The study thematically discusses various compound groups, eg, carbohydrates, proteins, and triglycerides (oils). Since often the monomers or building blocks of these biopolymers are of significant importance and produced in large amounts, the applications of these compounds are also reviewed.

[Investigation on cellular uptake and cytotoxicity of plasmid DNA-chitosan nanoparticles].

Two kinds of chitosan of different molecular weight (50 kDa and 400 kDa) were employed to form nanoparticles with 32P-labeled plasmid DNA at different N/P ratios by complex coacervation method. The characteristics of chitosan gene nanoparticles (CGN) were measured. The cellular uptake of DNA nanoparticles was evaluated by A10 and K562 cells. The in vitro cytotoxicity of DNA nanoparticles was determined by the MTT assays. Cellular uptake of the DNA nanoparticles increased with increasing chitosan molecular weight and N/P ratio. It also correlated with the zeta potential of the DNA nanoparticles. Chitosan-DNA nanoparticles were much less cytotoxic when compared with Lipofectamine 2000-DNA nanoparticles.