Abundant Amino Research Articles

Removal of heavy metals by biopolymer (chitosan)/nanoclay composites

ABSTRACTMore recently, polymer/inorganic hybrid adsorbents have emerged new class of adsorbents for deep removal of trace pollutants and among them chitosan is a natural biodegradable and non-toxic polysaccharide. Natural clay minerals with properties like abundance in most continents of the world, high sorption properties, potential for ion exchange, and with their low cost, are strong candidates as adsorbents. In this study, chitosan/nanoclay composites were developed by using surfactant-clay (organo-clay) and chitosan biopolymer and synthesized by polymerization method. Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and sorptometric analysis characterized the porous chitosan/nanoclay composites. The adsorption of copper (II) and Nickel (II) ions onto the prepared chitosan/nanoclay composites from an aqueous solution using batch adsorption was examined. The results showed that benefiting from the surface property of clay, the abundant amino and hydroxyl functional groups of chitosan, the adsorbent provides adequate and versatile adsorption for the Cu (II) and Ni (II) ions under investigation. The best adsorption capacities were obtained as 176 mg/g and 144 mg/g for Cu and Ni, respectively. These values are higher than obtained ones (135 mg/g for Cu and 65 mg/g for Ni) in the literature up to now.

Synthesis of dodecylamine-functionalized graphene quantum dots and their application as stabilizers in an emulsion polymerization of styrene

Pickering emulsions have attracted considerable interest due to their potential applications in many fields, such as the food, pharmaceutical, petroleum and cosmetics industries. The study reports the synthesis of dodecylamine-functionalized graphene quantum dots (d-GQDs) and their implementation as stabilizers in an emulsion polymerization of styrene. First, d-GQDs are prepared by thermal pyrolysis of citric acid and dodecylamine in 0.1M ammonium hydroxide. The resulting d-GQDs consist of small graphene sheets with abundant amino, carboxyl, acylamino, hydroxyl and alkyl chains on the edge. The amphiphilic structure gives the d-GQDs high surface activity. The addition of d-GQDs can reduce the surface tension of water to 30.8mNm−1 and the interfacial tension of paraffin oil/water to 0.0182mNm−1. The surface activity is much better than that of previously reported solid particle surfactants for Pickering emulsions and is close to that of sodium dodecylbenzenesulfonate, which is, a classical organic surfactants. Then, d-GQDs are employed as solid particle surfactants for stabilizing styrene-in-water emulsions. The emulsions exhibit excellent stability at pH 7. However, stability is lost when the pH is more than 9 or less than 4. The pH-switchable behaviour can be attributed to the protonation of amino groups in a weak acid medium and dissociation of carboxyl groups in a weak base medium. Finally, 2,2′-azobis(2-methylpropionitrile) is introduced into the Pickering emulsions to trigger emulsion polymerization of styrene. The as-prepared polystyrene spheres display a uniform morphology with a narrow diameter distribution. The fluorescent d-GQDs coated their surfaces. This study presents an approach for the fabrication of amphiphilic GQDs and GQDs-based functional materials, which have a wide range of potential applications in emulsion polymerization, as well as in sensors, catalysts, and energy storage.

Monosodium glutamate has no cytotoxic effect on mouse mesenchymal stem cells

SUMMARY Aim/Backround: Monosodium glutamate as a food additive is a substance added to food to preserve flavor or enhance its taste and appearance. Monosodium glutamate is the sodium salt of glutamic acid, one of the most abundant naturally-occurring non-essential amino acids. U.S. Food and Drug Administration reported that monosodium glutamate is safe for use in food. However, the excessive use of monosodium glutamate causes dizziness, nausea and vomiting. Due to reports, it causes obesity. We aimed to find out the cytotoxiciy of monosodium glutamate and the role on the selected genes, which have role on obesity. Methods: In our study, we used mice which are known to be the most sensitive in terms of toxicity. We were studied the cytotoxic effects of monosodium glutamate on mouse mesenchymal stem cells at monosodium glutamate doses below. Also we analyzed leptin-lep and ghrelin / obestatin in prepropeptide-GHRL gene expressions in order to find out the role of monosodium glutamate in obesity. Result: Monosodium glutamate below the toxic dose does not have a cytotoxic effect on mouse mesenchymal stem cells. Also no expression change observed in genes which are known to be associated with obesity. Conclusion: Our results support that monosodium glutamate has no toxic effect on stem cells in uses in certain doses. Key words: Monosodium glutamate, mouse mesenchymal stem cells, leptin gene, ghrelin/obestatin prepropeptide gene. Running Title: MSG has no ctotoxicity

The effect of thermal processing in oil on the macromolecular integrity and acrylamide formation from starch of three potato cultivars organically fertilized

AbstractStarches from three organically produced cultivars of potato tuber (Lady Rosetta, Spunta and Voyager) have been studied in relation to (i) acrylamide production (ii) macromolecular integrity after frying with extra virgin olive oil, soybean oil and corn oil. During cultivation, a treatment involving the combination of nitrogen, phosphorus and potassium fertilization under organic farming was applied (N1, P2, K1 where Ν1 = 1.3 g Ν per plant, P2 = 5.2 g P2O5 per plant, Κ1 = 4.0 g K2O per plant).Potatoes fried in olive oil retained the highest glucose concentrations for all cultivars 0.85 ± 0.2 mmol/kg, followed by 0.48 ± 0.2 for those fried in corn oil and 0.40 ± 0.1 mmol/kg for those fried in soybean oil. The highest average fructose concentration was recorded for the samples fried in corn oil as 0.81 ± 0.2, followed by 0.80 ± 0.2 and 0.68 ± 0.3 mmol/kg for the samples fried in olive and soybean oils, respectively. Asparagine was the most abundant free amino acid in the three varieties tested, foll...

Preparation and characterization of chitosan-clay nanocomposites for the removal of Cu(II) from aqueous solution

In the present study, chitosan assembled on gold and silver nanoparticles were prepared and characterized by UV–vis, TEM, EDX and DLS techniques. The nanocomposites chitosan (Ch)/clay, chitosan (Ch)/AgNPs/clay and chitosan (Ch)/AuNPs/clay were prepared by solution mixing method and characterized by FTIR, XRD, and SEM techniques. The adsorption of copper(II) ions onto the prepared hybrid composites from an aqueous solution using batch adsorption was examined. The results showed that benefiting from the surface property of clay, the abundant amino and hydroxyl functional groups of chitosan, the adsorbent provides adequate and versatile adsorption for the Cu(II) ions under investigation. The batch adsorption experiments showed that the adsorption of the Cu(II) is considerably dependent on pH of milieu, the amount of adsorbent, and contact time. Batch adsorption studies revealed that the adsorption capacity of Cu(II) increased with increase in initial concentration and contact time with optimum pH in the range around neutral. The maximum uptake of Cu(II) ions by (Ch)/AgNPs/clay composite was found to be 181.5mg/g. The adsorption efficiency of Cu(II) ions by prepared (Ch)/AgNPs/clay and (Ch)/AuNPs/clay is bigger than that the individual chitosan (Ch)/clay composite which clarifies the role of metal nanoparticles in enhancement the adsorption characters. The study suggests that the (Ch)/AgNPs/clay hybrid composite is a promising nano-adsorbent for the removal of Cu(II) ions from aqueous solution.

추출용매에 따른 큰느타리 버섯의 영양성분 및 생리활성

Physiological activities of 70% methanol, fermented ethanol and hot-water extracts of Pleurotus eryngii were investigated. Free radical scavenging activities of P. eryngii extracts were determined according to the elimination of DPPH radicals. Their nitrite scavenging activity and total polyphenol content were also determined. Amino acid analysis showed that phenylalanine (Phe) and glutamic acid (Glu) are most abundant essential and non-essential amino acids in the analyzed extracts. The hot-water extract of ASI 2394 represented the highest antioxidant activity with the DPPH radical scavenging rate value of . ASI 2820 displayed the superior capacity to eliminate nitrate regardless of extraction solvents. The hot-water extract of ASI 2887 had the highest content of polyphenol. Our results showed that P. eryngii is well qualified as a functional food.

Preparation of graphene oxide/chitosan/FeOOH nanocomposite for the removal of Pb(II) from aqueous solution

In the present study, a graphene oxide/chitosan/FeOOH (GO/Ch/FeOOH) nanostructured composite was prepared and used as an adsorbent for the removal of Pb(II) ions from aqueous solution. The nanocomposite was characterized by FT-IR, XRD, and SEM techniques. Several important parameters influencing the adsorption of Pb(II) ions such as pH (3–7), temperature (25–80°C), shaking speed (150–800rpm), contact time (10–70min), and sorbent mass (10–100mg) were studied. The results showed that, benefiting from the surface property of graphene oxide, the abundant amino and hydroxyl functional groups of chitosan, the adsorbent provides adequate and versatile adsorption for the Pb(II) ions under investigation. The batch adsorption experiments showed that the adsorption of the Pb(II) is considerably dependent on pH of milieu, amount of adsorbent, and contact time. The Freundlich and Langmuir adsorption models were used for the mathematical description of adsorption equilibrium and isotherm constants. Both models were applicable for the description of Pb(II) adsorption isotherm in the concentration range studied. However, Langmuir model showed higher correlation coefficient (R2) than Freundlich model. The study suggests that the GO/Ch/FeOOH is a promising nano adsorbent for the removal of Pb(II) ions from aqueous solution.

Selective adsorption of catalyst and copper plating for additive fabrication of conductive patterns and through-holes

A novel patterning-adsorption-plating process to additively fabricate conductive patterns and through-holes of double-sided flexible printed circuit is developed. Firstly, through-holes were drilled in substrate. Then ion-adsorption ink was dip-coated to form the adsorption film on the surfaces of substrate and through-holes. Mask was printed to expose the patterns and the through-holes. Afterwards, silver ion was selectively adsorbed to the exposed parts. Finally, after dissolving the mask, the patterns and the through-holes were metalized by electroless plating of copper. The ion-adsorption ink is composed of polysiloxane and solvent. The polysiloxane was prepared by hydrolyzing 3-aminopropyltriethoxy silane with 3-mercaptopropyltriethoxy silane together, thus the formed ion-adsorption film contains abundant amino and mercapto groups. Amino groups can adsorb silver ion by complexation. Mercapto groups increase the hydrophobicity of the adsorption film, improving the stability in alkaline solution. Special solvent used in the ink leads to the coarse adsorption film, so the mechanical anchor between the deposited copper and adsorption film is improved, resulting in a better adhesion. After 60min plating, the copper patterns with 1.87μm in thickness and 9.1mΩ in square resistance was prepared, the adhesion can reach 5B. The prepared double-sided FPC shows high conductivity and adhesion, proving that PAP process possesses high potential in industrial production.

Evaluation of the Toxicity of a Single Oral Dose of N-(D-Ribopyranosyl)taurine Sodium Salt in Mice.

Taurine is a simple sulfur-containing compound and one of the most abundant free amino acids in human and animal tissues. N-(d-Ribopyranosyl)taurine sodium salt (T-Rib) is a newly synthesized taurine-carbohydrate derivative from the reaction between taurine and ribose. The purpose of this study was to evaluate the toxicity of a single oral dose of T-Rib in mice to verify its safety profile. N-(d-Ribopyranosyl)taurine sodium salt was orally administered at a dose of 0, 2,000, and 5,000 mg/kg body weight (BW) to 12 male and 12 female ICR mice. The mortality rate, clinical signs of toxicity, and BW were monitored for 14 days. After sacrificing, histological examination of liver tissue was performed using the paraffin method. All mice appeared to be healthy and normal throughout the observation period. No mortality and no abnormal clinical signs were observed in the experimental groups. Furthermore, no abnormal changes in BW and microscopic liver histology were found in the experimental groups. From the results of this study, we suggest that the administration of a single oral dose of T-Rib is not toxic to ICR mice at the highest tested dose of 5,000 mg/kg BW. Further studies on the toxicity of repeated oral doses are needed to prove the safety of T-Rib for its development as an ingredient of health functional food (HFF).

Facile self-assembly of magnetite nanoparticles on three-dimensional graphene oxide–chitosan composite for lipase immobilization

Three dimensional (3D) magnetic graphene oxide–chitosan (GO–CS) composites with orderly self-assembled magnetite (Fe3O4) nanoparticles (GO–CS–Fe3O4) were successfully fabricated. First, the covalent functionalization of graphene oxide (GO) using chitosan (CS) was successfully accomplished via a facile amidation process, forming a 3D network. In the as-fabricated GO–CS composites, GO sheets remained less aggregated, exhibiting a large surface area, and the interconnected pores in the hydrogels allowed object molecules to diffuse easily into the composites. Subsequently, the GO–CS–Fe3O4 composites were synthesized using FeCl3·6H2O and GO–CS composite as the starting materials through a solvothermal reaction. The resulting composite combined the features of the high surface area of GO, abundant amino, and hydroxyl functional groups of CS, and the magnetic response of magnetic nanoparticles. For further application, these composites were utilized to immobilize Candida rugosa lipase via different routes, and they showed excellent immobilization capacities.

TM-15 * GLUTAMINE BASED PET IMAGING FACILITATES ENHANCED METABOLIC DETECTION OF GLIOMAS IN VIVO

Glutamine is the most abundant plasma amino acid and many cancers show altered glutamine metabolism. We evaluated glutamine uptake and metabolism in gliomas using PET imaging and biochemical approaches. We demonstrate that glutamine is a key TCA cycle anaplerotic substrate and is metabolized to generate 2-HG in IDH1-mutant gliomas. PET imaging with18F-labeled glutamine (18F-FGln) showed high uptake in gliomas in vivo but low background uptake in the surrounding brain in RCAS-PDGF/PTEN null and IDH1-mutant glioma animal models, facilitating clear tumor delineation in contrast to that seen with 18F-FDG. We did not observe 18F-FGln uptake in animals with neuroinflammation or animals with a disrupted BBB. Further, 18F-FGln uptake was specifically reduced on chemo/radiation therapy. Finally, 18F-FGln showed high avidity in human glioma with low uptake in the surrounding brain. These data suggest that 18F-FGln is specifically taken up by gliomas, can be used to assess the metabolic state of gliomas in vivo and may serve as a valuable tool in the clinical management of gliomas.

Bioprocess production of sea cucumber rice wine and characterization of functional components and antioxidant activities

A new production bioprocess for sea cucumber rice wine (SCRW) was established. The traditional production technology of Chinese rice wine was combined with addition of sea cucumber hydrosylates. The optimal enzymatic conditions of sea cucumber and the fermentation process of SCRW were determined. The weight of sea cucumber enzymatic hydrolysates was 2.5% of millet while cooking the millet. SCRW contained abundant free amino acids (30 total at 1,681.216 mg/L), oligosaccharides (4 total at 10,999.380 mg/L), total phenols (658.850 mg/L), and mineral elements (9 total at 1,911.353 mg/kg), and an antioxidant activity, all of which were higher than for control rice wine (CRW). Galactosamine and glucuronic acid, both sea cucumber polysaccharides, were present in SCRW, but not in CRW.

Removal of Acid Orange 7 from aqueous solution using magnetic graphene/chitosan: A promising nano-adsorbent

Magnetic graphene/chitosan (MGCh) nanocomposite was fabricated through a facile chemical route and its application as a new adsorbent for Acid Orange 7 (AO7) removal was also investigated. After synthesis, the full characterization with various techniques (FTIR, XRD, VSM, and SEM) was achieved revealing many possible interactions/forces of dye–composite system. The results showed that, benefiting from the surface property of graphene oxide, the abundant amino and hydroxyl functional groups of chitosan, and from the magnetic property of Fe3O4, the adsorbent possesses quite a good and versatile adsorption capacity to the dye under investigation, and can be easily and rapidly extracted from water by magnetic attraction. The maximum absorption capacity was reached at initial pH 3 and 120min contact time. The batch adsorption experiments showed that the adsorption of the AO7 is considerably dependent on pH of milieu, amount of adsorbent, and contact time. The adsorption kinetics and isotherms were investigated to indicate that the kinetic and equilibrium adsorption were well-described by pseudo-first order kinetic and Langmuir isotherm model, respectively. The adsorption behavior suggested that the adsorbent surface was homogeneous in nature. The study suggests that the MGCh is a promising nano adsorbent for removal of anionic azo dyes from aqueous solution.

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles.

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings.

Nutritional Characteristics of Black Rockfish (Sebastes schlegeli) Fed a Diet of Fish Skin

This study investigated the effects of diets substituted with different levels (0, 5, 10, and 20%) of flounder skin meal (FSM) on the nutritional composition of black rockfish Sebastes schlegeli. Fish (10.05 ± 0.44 g) were fed to apparent satiation twice daily for 8 weeks. Adding FSM decreased crude lipid levels and increased crude protein and ash. The abundant fatty acids in the FSM-added group were C16:0, C18:1-cis (n9), and C22:6n-3. The major amino acids in the samples were glutamic acid, aspartic acid, glycine, leucine, alanine, lysine, and arginine. The abundant free amino acids in the FSM-added group were taurine, glutamic acid, alanine, leucine, and arginine. Six free sugars were found in all groups. Glucose was predominant, followed by mannose, rhamnose, fucose, fructose, and ribose. Among the three organic acids in the whole body of black rockfish, lactic acid was predominant, followed by citric acid and oxalic acid. Total organic acid content in the control was significantly higher than those of FSM substitution groups.

Nutritional Composition Changes in Skate (Raja kenojei) during Different Ripening Periods

In order to suggest fundamental data on the nutritional composition of the Korean traditional food, ripened skate, this study investigated the proximate composition, organic acid, free sugar, fatty acid, total amino acid, and macromolecule levels of skates at different ripening periods. Longer ripening periods resulted in decreased moisture levels and increased protein and ash levels. The total organic acid content increased until the 15th day of ripening, but decreased at 20 days. Phosphoric acid, oxalic acid, and lactic acid were the dominant organic acids. Eight free sugars were detected, ribose, glucose, and sucrose being the dominant forms, which significantly decreased with ripening. Palmitic and lignoceric acid were abundant in saturated fatty acids, oleic acid and palmitoleic acid were abundant in monounsaturated fatty acids, and linolenic acid, docosahexenoic acid, and arachidonic acid were abundant in polyunsaturated fatty acids. The major amino acids were glutamic acid, lysine, aspartic acid, and leucine and the total levels increased with ripening. The most abundant free amino acids were urea, sarcosine, taurine, and β-alanine, which decreased with ripening. Phosphoserine, phosphoethanolamine, α-aminobutyric acid, and cysteine levels increased.

Synthesis of magnetic β-cyclodextrin–chitosan/graphene oxide as nanoadsorbent and its application in dye adsorption and removal

Magnetic β-cyclodextrin–chitosan/graphene oxide materials (MCCG) were fabricated through a facile chemical route and their application as excellent adsorbents for dye removal were also demonstrated. The characteristics results of FTIR, SEM, TEM and XRD showed that MCCG was successfully prepared. The results showed that, benefiting from the surface property of graphene oxide, hydrophobicity of β-cyclodextrin, the abundant amino and hydroxyl functional groups of chitosan, and from the magnetic property of Fe3O4, the adsorbent possesses quite a good and versatile adsorption capacity to the dye under investigation, and can be easily and rapidly extracted from water by magnetic attraction. Most importantly, the adsorbent can be easily and efficiently regenerated for reuse with hardly any compromise of the adsorption capacity. The adsorption kinetics, isotherms and thermodynamics were investigated to indicate that the kinetics and equilibrium adsorptions were well-described by pseudo-second-order kinetic and Langmuir isotherm model, respectively. The thermodynamic parameters suggested that the adsorption process was spontaneous and endothermic in nature. The inherent advantages of the nano-structured adsorbent, such as adsorption capacity, easy, handy operation, rapid extraction, and regeneration, may pave a new, efficient and sustainable way towards highly-efficient dye pollutant removal in water and wastewater treatment.

Chitin Nanofiber Membranes for Chiral Separation

Nanofiber membranes for chiral separation were prepared from chitin, which is the most abundant natural amino polysaccharide. The membrane showed chiral separation ability by adopting concentration gradient as a driving force for membrane transport. In other words, the chitin nanofiber membrane selectively transported the D-isomer of glutamic acid (Glu), phenylalanine (Phe), and lysine (Lys) from the corresponding racemic amino acid mixtures.

Tandem Mass Spectrometry: A New Platform for Fluxomi

C substrates could be generated using gas chromatography coupled tandem MS (GC-MS/MS) and the GC-MS/MS data could be used to derive metabolic fluxes with similar accuracy and precision to those obtained using NMR and significantly better than those using full-scan GC-MS. Later, Kiefer et al. [3] reported the determination of carbon labeling distribution of intracellular metabolites for fluxomics using liquid chromatography tandem MS (LC-MS/MS) and was able to determine the natural abundances of the carbon fractions m and m+1 from six phosphorylated metabolites from glycolysis and pentose phosphate pathway in E. coli with high accuracy. More recently, Ruhl et al. [4] exploited the measurement of the 13 C patterns of totally 27 intact and 19 fragmented metabolites from the central metabolic pathways in B. subtilis using LC-MS/MS, and the metabolic fluxes calculated using the LC-MS/MS data showed higher precision than those performed using solely full-scan LC-MS data [4]. Most importantly, these research demonstrated that tandem MS, especially LC-MS/MS that does not require chemical derivation like GC-MS/MS, can provide direct measurements of large sets of isotopic labeling patterns from intracellular intermediates and thus allow resolving fluxes for dynamic systems (non-steady state) and large-scale complex metabolic pathways, which are infeasible with the traditional NMR and MS based fluxomics methods as those rely on indirect measurements of the abundant proteinogenic amino acids and thus require long labeling experimental time for steady state to allow the incorporation of isotopes into proteins and can only derive fluxes for the central metabolic pathways that have the key nodes linked with protein biosynthesis. Given the promising applications of tandem MS for fluxomics, however, the technical aspects for isotopomer measurements have to be stressed. First, the methods for metabolite extraction and separation need to be developed or optimized to increase the coverage of detection of various catalogues of metabolites considering the diversity of the physico-chemical properties of the metabolome in an organism. Second, the tandem MS instrumental parameters such as the collision energy for fragmentation, the resolution of mass filter and the number of multiple reaction monitoring (MRM) etc. need to be optimized to capture as many as possible informative daughter mass spectra that are useful for solving the mathematical model and minimize the acquisition of redundant daughter mass spectra that complicate the mathematical

Oxidation of melatonin by taurine chloramine

Melatonin is widely known for its antioxidant, immunomodulatory, and anti-inflammatory effects. Hypochlorous acid (HOCl) is one example of an endogenous oxidant that is promptly neutralized by melatonin. Melatonin also inhibits myeloperoxidase, the enzyme that catalyzes the oxidation of chloride to HOCl. Taurine is the most abundant free amino acid in leukocytes. In activated neutrophils, taurine is converted to taurine chloramine (Tau-NHCl) through a reaction with HOCl. In addition, the related compound taurine bromamine (Tau-NHBr) can be released by neutrophils and eosinophils. The aim of this study was to investigate the reactivity of Tau-NHCl and Tau-NHBr with melatonin. We found that melatonin can react with either Tau-NHCl or Tau-NHBr, leading to the production of 2-hydroxymelatonin and N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK). The reaction was pH-dependent, and it occurs more rapidly at a slightly acidic pH. Tau-NHBr was significantly more reactive than Tau-NHCl. Using Tau-NHBr as the oxidizing agent, 1 mm melatonin was oxidized in less than 1 min. The pH dependence of the reaction with Tau-NHCl and the increased reactivity of Tau-NHBr can be explained by a mechanism based on the initial attack of chloronium (Cl(+)) or bromonium (Br(+)) ions on melatonin. We also found that the addition of iodide to the reaction medium increased the yield of AFMK. These findings could contribute to the establishment of new functions for melatonin in inflammatory and parasitic diseases, where the role of this indoleamine has been extensively investigated.