Multi-round recycling of green waste for the production of iron nanoparticles: synthesis, characterization, and prospects in remediation.

Due to the widespread applications of metal nanoparticles (NPs), green synthesis strategies have recently advanced, e.g., methods that utilize extracts made from different plant wastes. A particularly innovative approach to reducing large amounts of available household/agricultural green wastes is their application in nanoparticle generation. Regarding this, the aim of our work was to examine the possibility of upgrading green nanoparticle syntheses from an innovative economic and environmental point of view, namely by investigating the multiple recyclabilities of green tea (GT), coffee arabica (CA), and Virginia creeper (Parthenocissus quinquefolia) (VC) waste residues for iron nanoparticle (FeNPs) synthesis. The plant extracts obtained by each extraction round were analyzed individually to determine the amount of main components anticipated to be involved in NPs synthesis. The synthesized FeNPs were characterized by X-ray powder diffraction and transmission electron microscopy. The activity of the generated FeNPs in degrading chlorinated volatile organic compounds (VOC) and thus their future applicability for remediation purposes were also assessed. We have found that VC and especially GT residues could be reutilized in multiple extraction rounds; however, only the first extract of CA was suitable for FeNPs' generation. All of the obtained FeNPs could degrade VOC with efficiencies GT1-Fe 91.0%, GT2-Fe 83.2%, GT3-Fe 68.5%; CA1-Fe 76.2%; VC1-Fe 88.2%, VC2-Fe 79.7%, respectively, where the number (as in GT3) marked the extraction round. These results indicate that the adequately selected green waste material can be reutilized in multiple rounds for nanoparticle synthesis, thus offering a clean, sustainable, straightforward alternative to chemical methods.

Fruit juices are effective anti-amyloidogenic agents.

Amyloid fibril formation has been associated with a great variety of human diseases. Fruits contain different important bioactive molecules without causing various undesirable side effects, which are necessary for disease prevention and treatment. Here we report that various fruit juices inhibited the amyloid formation by α-chymotrypsin in aqueous ethanol at pH 7.0. Turbidity measurements, total phenolic content determination, as well as Congo red binding assay were used to analyse the inhibition of amyloid fibril formation. We showed that the black currant juice possessed the strongest inhibitory potential against protein aggregation because it contains the most polyphenolic compounds too and its effect was concentration dependent. Interestingly, white grapes, figs and bananas are relatively effective although they are not high in polyphenols. These fruits are typically sweet. The sugars in them also contribute to their effectiveness. Eating black currant can reduce the likelihood of formation of amyloid fibrils.

Peppermint extract inhibits protein aggregation.

The extracts of 7 herbs were screened and compared for their functional ability to inhibit the aggregation of trypsin as an appropriate model protein for in vitro fibrillation in aqueous ethanol at pH 7.0. Turbidity measurements, total phenolic content determination, aggregation kinetics, Congo red binding assay as well as transmission electron microscopy were used to analyse the inhibition of amyloid fibril formation. This correlated with the total phenolic content of the herb extracts. The peppermint extract proved to be the most potent anti-amyloidogenic agent. Results showed that the peppermint extract exerted dose-dependent inhibitory effect on trypsin fibril formation.

Coffee extracts effectively inhibit the formation of α-chymotrypsin amyloid-like fibrils in aqueous ethanol in vitro.

In this study, an in vitro α-chymotrypsin aggregation model was used to demonstrate that certain extracts of commercial coffees effectively inhibit protein aggregation in 55% ethanol at pH 7.0. To detect the anti-amyloidogenic effect of the various coffee extracts, turbidity measurements and Congo red binding assays were performed as well as the determination of the total polyphenol content of the extracts. The greatest fibril formation inhibitory effect was exerted by the Eduscho coffee extract, which contained also the most of the phenolic compounds. The Eduscho coffee extract inhibited the fibrillation of the α-chymotrypsin dose dependently. Coffee extracts are effective anti-aggregation agents, and their beneficial effects strongly correlate with the total phenolic content.

Inhibition of the formation of amyloid-like fibrils with spices, especially cloves.

During the study of inhibition of amyloid fibril formation, α-chymotrypsin protein was developed in 55% ethanol at pH 7.0. We investigated the inhibitory effect of different spices on amyloid fibril formation using turbidity measurements and Congo red binding assays. We found that all spices except the black pepper and caraway seed prevented fibril formation. The highest inhibition was measured with the clove, which reduced the amount of aggregates by 90%. We studied the inhibitory effect of the cloves at different concentrations on aggregation, it was found that the inhibitory activity of clove is dependent on concentration. We have measured the total phenolic content of the spice extracts too. Based on all these findings we have come to the following conclusion: Our results indicate that spices can contain other compounds too - not only phenolic compounds - which influence the formation of amyloid fibrils, and the effectiveness of various phenolic compounds are different.

Inhibition of the formation of amyloid-like fibrils using herbal extracts.

We tested the amyloid fibril formation inhibitory effect of seven teas diluted in 55% ethanol at pH 7.0 at a protein concentration of 0.15 mg/ml α-chymotrypsin. In the experiments we investigated the formation and inhibition of amyloid fibrils by turbidity measurements, aggregation kinetics experiments and Congo red binding assay. The results suggest that the different teas effectively inhibit the formation of amyloidlike fibrils. The two most potent inhibitors were peppermint and melilot, extracts which almost completely inhibited the formation of aggregates in 5-fold dilution. The inhibitory effect on the aggregation formation of melilot and peppermint extracts was concentration dependant. The extent of inhibition was found to be proportional with the total concentration of phenolic compounds.

The Inhibitory Effect of Panax Ginseng Extract on Amyloid-like Fibril Formation of Trypsin in Aqueous Ethanol.

BACKGROUND: In case of several chronic diseases, prevention is could be more effective than treatment. Functional foods that contain significant amounts of bioactive components gained considerable attention not only in traditional but in modern medicine as well. We have investigated how P. ginseng extract inhibits the in vitro formation of amyloid-like fibrils of phenylmethylsulfonyl- trypsin (PMS-trypsin) in 60% ethanol at pH 7.0. The model system used is non-physiological, but it is capable of detecting the anti-amyloidogenic effect of the various agents. OBJECTIVE: The main objective of this study was to examine the possible inhibitory effect of ginseng extract on amyloid-like fibril formation of trypsin in aqueous ethanol. METHODS: The amyloid formation and aggregation kinetics of PMS-trypsin was studied by turbidity measurements, Congo Red (CR) binding assays, size exclusion chromatography and Electronic Circular Dichroism (ECD) measurements and the shapes of amyloid fibrils became visible by Transmission Electron Microscopy (TEM). RESULTS: In the presence of 500-fold diluted P. ginseng extract in the incubation mixture, the absorption at 350 nm decreased to 47.1% after incubation for 24 h, compared relative to the sample which contained no additives. CR binding experiments suggested that the aggregates in our samples have amyloid-like properties, and P. ginseng extract inhibits the amyloid-like fibril formation of PMS-trypsin depending on concentration. Our results show that the ginseng extract does not bind to the fibrils. In the absence of P. ginseng extracts large sized colloid aggregates were abundant. Adding P. ginseng extracts to our samples decreased the light dispersion of the solution. This is due to the decrease of the rate of the aggregation or to the smaller size of the aggregates evolved. Our results show that the presence of ginseng extract helps to maintain the native structure of the protein. In the presence of 500-fold diluted P. ginseng extract, TEM images demonstrated, that P. ginseng extract has inhibitory effect on the formation of amyloid-like fibrils of PMS-trypsin. CONCLUSION: The results indicated that P. ginseng extract significantly inhibits the formation of amyloid-like fibrils of PMS-trypsin in aqueous ethanol, and helps to maintain the native structure of the protein. The rate of inhibition depends on concentration. P. ginseng extract is an efficient antiamyloidogenic agent.

Inhibition of Amyloid-like Fibril Formation of Trypsin by Red Wines.

The aim of the present study was to examine the potential role and applicability of dietary supplements in reducing the risk of development of amyloid diseases associated with the gastrointestinal tract, such as type II diabetes. Trypsin, a well-known serine protease was used as a model protein in our experiments. The effect of various red wines on the formation of amyloid-like fibrils of trypsin was studied in vitro, in aqueous ethanol, at pH 7.0. Turbidity measurements, aggregation kinetics experiments, Congo red binding assays and electronic circular dichroism spectroscopic measurements were used to follow the aggregation process in the presence or absence of various red wines. The results suggest that red wines effectively inhibit the formation of amyloid-like fibrils of trypsin and the inhibitory effect is dose-dependent. The extent of inhibition was found to be proportional to the total concentration of phenolic compounds.

Amyloid-like Fibril Formation by Trypsin in Aqueous Ethanol. Inhibition of Fibrillation by PEG.

The formation of amyloid-like fibrils was studied by using the well-known serine protease trypsin as a model protein in the presence of ethanol as organic solvent. Trypsin forms amyloid-like fibrils in aqueous ethanol at pH = 7.0. The dye Congo red (CR) was used to detect the presence of amyloid-like fibrils in the samples. The binding of CR to fibrils led to an increase in absorption intensity and a red shift in the absorption band of CR. Thioflavin T (ThT) and 8-anilino-1- naphthalenesulfonic acid (ANS) binding assays were employed to characterize amyloid-like fibril formation. The ThT binding assay revealed that the protein exhibited maximum aggregation in 60% (v/v) ethanol after incubation for 24 h at 24 (o)C. The ANS binding results indicated that the hydrophobic residues were more exposed to the solvent in the aggregated form of the protein. The effects of polyethylene glycol (PEG) on the formation of amyloid-like fibrils was studied in vitro. The aggregation of trypsin was followed via the kinetics of aggregation, the far-UV circular dichroism (CD) and transmission electron microscopy (TEM) in the presence and absence of PEG. The CD measurements indicated that the protein aggregates have a cross-beta structure in 60% ethanol. TEM revealed that trypsin forms fibrils with a thread-like structure. The inhibitory effect of PEG on the aggregation of trypsin increased with rising PEG concentration. PEG therefore inhibits the formation of amyloid-like fibrils of trypsin in aqueous ethanol.

The formation of amyloid-like fibrils of α-chymotrypsin in different aqueous organic solvents.

The formation of amyloid-like fibrils of α-chymotrypsin was studied in aqueous ethanol, methanol, tertbutanol, dimethylformamide and acetonitrile. Thioflavin T (ThT), Congo red (CR) and 1-anilino-8-naphthalenesulfonic acid (ANS) binding, turbidity, intrinsic fluorescence and far-UV circular dichroism measurements were employed to characterize the amyloid fibril formation. The greatest extent of fibril formation after incubation for 24 h at pH 7.0 and at 24 °C was in ethanol at 55%, in methanol and dimethylformamide (DMF) at 60-70% and in tert-butanol at 60-80%. The ANS binding and intrinsic fluorescence results showed that the hydrophobic residues are more solvent-exposed in the aggregated form of α-chymotrypsin. The ThT, CR binding and far-UV CD measurements indicated that the formation of the cross-ß structure of α-chymotrypsin depends on the polarity of the organic solvent. To determine the role of surface charges in the aggregation, chemically modified forms of α-chymotrypsin were prepared. The citraconylated and succinylated enzymes exhibited a higher and the enzyme forms modified with aliphatic aldehydes a lower propensity for aggregation. These results suggest the important role of surface charges in the aggregation of α-chymotrypsin.

The effects of Al(III) speciation on the activity of trypsin.

The effects of the different forms of Al(III) on the catalytic activity of the serine protease trypsin were studied. Enzyme activity was measured by BAEE assay in the presence of AlCl(3), Al(III):lactic acid 1:3, Al(III):maltol 1:3 or Al(III):nitrilotriacetic acid (NTA) 1:1 at a nominal Al(III) concentration of 0.01 M, and the ligand alone at pH 7.4 at 25 degrees C. Maltol and NTA caused approximately 30% inhibition, while that for the corresponding Al(III) complex was less than half of this. Al(III) in the form of the chloride or in three equivalents of lactic acid did not influence the activity of the enzyme, probably because most of the Al(III) was precipitated as Al(OH)(3). No direct interaction could be detected between the enzyme and the Al(III) complexes, either by ultrafiltration or by CD spectroscopy. These results strongly suggest that there is no direct involvement of Al(III) in the enzymatic reactions of trypsin.