Oxidation Of Dopa Research Articles

Enantioselective and Band-Gap Modulation in Photocatalysis of Metal-Free Chiral Carbon Dots.

Photodriven chiral catalysis is the combination of photocatalysis and chiral catalysis and is considered one of the cleanest and most efficient methods for the synthesis of chiral compounds or drugs. Furthermore, due to the potential metal contamination associated with most metal-based catalysts, metal-free chiral photocatalysts are ideal candidates. In this work, we demonstrate that metal-free chiral carbon dots (CDs) exhibit size-dependent enantioselective photocatalytic activity. Using serine as the raw material, chiral CDs with well-defined structures and average sizes of 2.22, 3.01, 3.70, 4.77, and 7.21 nm were synthesized using the electrochemical method. These chiral CDs possess size-dependent band gaps and exhibit photoresponsive enantioselective catalytic activity toward the oxidation of dihydroxyphenylalanine (DOPA). Under light-assisted conditions, chiral CDs (L72, 500 μg/mL) exhibit high selectivity (selectivity factor: 2.07) and maintain a certain level of catalytic activity (1.34 μM/min) even at a low temperature of 5 °C. The high catalytic activity of the chiral CDs arises from their photoelectrons reducing O2 to generate O2-, as the active oxygen species for DOPA oxidation. The high enantioselectivity of the chiral CDs is attributed to their differential adsorption capabilities toward DOPA enantiomers. This study provides a new approach for designing metal-free chiral photocatalysts with high enantioselectivity.

Artificial peroxidase of short peptide and hemin co-assemblies with selective chiral catalytic activity in DOPA oxidation

Chiral selectivity is one of the merits of natural enzymes in the catalysis of various biochemical reactions, and is also the ambition of artificial enzyme development. In this paper, we have fabricated a kind of artificial peroxidase through the co-assembly of amphiphilic short peptide and hemin. Ac-I3LH-NH2 self-assembled into right handed helical nanofibers, and Ac-I3DH-NH2 self-assembled into left handed helical nanofibers. Ac-I3L/DH-NH2 co-assembled with hemin through the coordination of imidazole group on histidine side chain and Fe(III) in hemin porphyrin ring. Hemin did not destroy the left or right helical morphologies of peptide nanofibers during co-assembly. The activity and chiral selectivity of artificial peroxidases have been assessed with L- and D-type DOPA as the substrates, which can be oxidized into dopachrome by H2O2. The results showed that hemin with right-handed nanofibers of Ac-I3H-NH2 showed higher activity in D-DOPA oxidation, while hemin with left-handed nanofibers of Ac-I3DH-NH2 showed higher activity in L-DOPA oxidation. It was supposed that both the conformation of imidazole group in histidine residues and the handedness of peptide nanofibers affected the chiral selectivity of the artificial peroxidase. The chiral properties have been transferred from the short peptide molecules to self-assembled nanofibers, and finally to the catalytic performance of hemin in the co-assemblies.

Evaluation and Comparison of the Antimelanogenic Properties of Different Solvent Fractionated Cnidium japonicum Extracts in B16F10 Murine Melanoma Cells.

Cnidium japonicum is a biennial halophyte found in the salt marshes and shores of Korea and widely used in traditional Korean medicine as an ingredient. This study investigated and compared the antimelanogenic effect of solventpartitioned fractions of C. japonicum extract (CJEFs) in a B16F10 mouse melanoma cell model, focusing on tyrosinase activity and production. Melanogenesis is the process in which skin pigment melanin is produced through tyrosinase activity. Overproduction of melanin is the primary reason behind several skin disorders such as freckles, spots, and hyperpigmentation. The antimelanogenic capacity of CJEFs was initially screened by their tyrosinase inhibitory effects, prevention of dihydroxyphenylalanine (DOPA) oxidation, and suppression of melanin production. The inhibition of tyrosinase activity and DOPA oxidation by CJEFs was suggested to be related to the downregulation of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2, which was confirmed using mRNA and protein expression levels. Moreover, the glycogen synthase kinase 3 beta- and cyclic adenosine monophosphate response element-binding protein-related signaling pathways were inhibited by treatment with CJEFs, indicating their action mechanism. All the tested CJEFs exerted similar effects on tyrosinase activity and production. However, among those, 85% aq. MeOH was the most active fraction to suppress the signaling pathway that produces tyrosinase. These results suggest that especially the MeOH fraction of C. japonicum extract serves as a potential source of bioactive substances, with effective antimelanogenesis properties.

In vitro screening of extracts from 38 marine animal resources for novel cosmeceutical activities

Marine resources have various biological activities and their constituents are more novel than those of land organisms. Several biologically active constituents have been found in marine organisms. Recently, many studies have reported that marine animals (MAs) can be used as functional ingredients in functional foods or nutraceutical due to their health benefits. However, no studies have extensively investigated the cosmeceutical activities of MAs extracts. Here, 70% ethanol extracts of 38 MAs were investigated for their activities of whitening and anti-aging properties for use as materials in novel cosmeceuticals. Anti-aging activities were determined by skin aging-related enzyme activities (anti-collagenase, anti-elastase, anti-hyaluronidase) and whitening activities (anti-tyrosinase, anti-3,4-dihydroxyl-L-phenylalanine [DOPA] oxidation) evaluated by colorimetric method. Among the 38 MAs, we found that Urechis unicinctus and Petrosia corticata extracts showed the strongest inhibitory effects against tyrosinase and DOPA oxidation, respectively. Our results additionally showed that Protankyra bidentata extract might provide a major source of anti-hyaluronidase and anti-elastase; meanwhile, anti-collagenase effects were similar in most MAs. Overall, these results suggest that extracts of marine animals have potential as a tyrosinase, collagenase, elastase, and hyaluronidase inhibitors. Taken together, MA resources could be considered as a novel cosmeceutical agent to be applied in cosmetic industry.

Oxidative stress and its impact on skin, scalp and hair.

Oxidative stress is an unbalanced condition in which the tissues of the body are not sufficiently able to counteract either exogenous or endogenous sources of reactive oxygen species. Oxidative stress is strongly associated with ageing, both local and systemic, as well as a wide range of local health conditions. This review focuses on the oxidative stress data known for skin, scalp and hair. This oxidative stress may be the 'currency' by which an unhealthy scalp leads to deleterious consequences to the hair. The ramifications of this scalp oxidative stress to normal hair elongation, retention and replacement are discussed.

Oriented in situ immobilization of a functional tyrosinase on microcrystalline cellulose effectively incorporates DOPA residues in bioengineered mussel adhesive protein.

Catechol-containing polymers such as mussel adhesive proteins (MAPs) are attractive as biocompatible adhesive biomaterials, and the catecholic amino acid 3,4-dihydroxyphenyl-L-alanine (DOPA) is considered a key molecule in underwater mussel adhesion. Tyrosinases can specifically convert tyrosine to DOPA without any cofactors. However, their catalytic properties still need to be adjusted to minimize unwanted DOPA oxidation via their diphenolase activity and catechol instability at neutral and basic pH values in the reaction products. In this work, we constructed a novel functional tyrosinase, mTyr-CNK_CBM, by fusion of mTyr-CNK with a cellulose-binding motif (CBM) for oriented in situ immobilization on microcrystalline cellulose via the C-terminal CBM without any additional purification steps. mTyr-CNK_CBM showed optimal catalytic activity at pH 4.5-6.5 and room temperature and had a high monophenolase/diphenolase activity ratio (Vmax mono/Vmax di = 2.08 at pH 6 and 25°C). mTyr-CNK_CBM exhibited 2.17-fold higher (as a unimmobilized free enzyme) and similarly high (upon immobilization) in vitro DOPA modification of a bioengineered MAP compared to a commercially available mushroom tyrosinase. Moreover, the immobilized mTyr-CNK_CBM showed long-term storability and improved reusability. These results clearly demonstrate a strong potential for practical use of immobilized mTyr-CNK_CBM as a monophenol monooxygenase in preparing biocompatible DOPA-tethered biomaterials and other catechol-containing polymers.

Spermidine promotes melanin production through an MITF signalling pathway.

Melanin plays an important role in determining skin colour. Apoptosis of melanocytes and defect in melanin production cause vitiligo. Various studies have been conducted to treat the disease, but its treatment is still difficult. Therefore, this study aimed to investigate the effect of spermidine, which is known as an inhibitor of ageing-related oxidized proteins, on melanogenesis. Even though spermidine above 50 μM had no effect on antioxidant activity and DOPA oxidation, it displayed tyrosinase activity. However, spermidine at 2000 μM was cytotoxic in B16F1 cells using MTT assay. Spermidine above 125 μM decreased the amount of intracellular hydrogen peroxide in a concentration-dependent manner in DCFH-DA analysis. It was also found that spermidine above 2000 μM increased melanin synthesis in living cells. However, spermidine above 1000 μM increased melanin synthesis in a concentration-dependent manner in H2 O2 -treated B16F1 cells. Furthermore, spermidine enhanced the expression of tyrosine hydroxylase via MITF transcription factor involved in melanogenesis in H2 O2 -treated B16F1 cells. Therefore, these results suggest that spermidine could be applied as a potential stimulator of melanin synthesis for the prevention of hair greying.

Synchronous fluorometric method for continuous assay of monophenolase activity

Tyrosinase is the key enzyme for melanogenesis with both monophenolase activity and diphenolase activity, which catalyzes the hydroxylation of tyrosine to L-DOPA and the further oxidation of DOPA, respectively. A continuous assay method was developed to directly monitor the real monophenolase activity using synchronous fluorescence. Complexation with borate to quench the native fluorescence of DOPA could selectively quantified the tyrosine in the binary mixture of tyrosine and DOPA under the wavelength difference Δλ = 67 nm for synchronous fluorescence. The limit of detection (LOD) for tyrosine were estimated to be 0.49 μM. Borate was used as a trapping agent for DOPA to abolish diphenolase activity, while hydroxylamine was used as a reducing agent to restore the catalytic cycle. The time course for consumption of tyrosine was established by monitoring the tyrosine fluorescence intensity at discrete intervals of 30 s. Calibration curve between monophenolase activity and tyrosinase concentration with range from 0.1830 U·mL−1 to 1.7034 U·mL−1, and LOD of 0.0721 U·mL−1. Using the proposed method, the Km and υmax for monophenolase was determined with values of 20.73 μM and 1.10 μM·min−1, respectively. Zinc ion was demonstrated to inhibit the monophenolase activity by competitive inhibition manner with IC50 of 14.36 μM. The assay method displayed a powerful application in kinetics and inhibitor screening for monophenolase.

Soluble Pearl Extract provides effective skin lightening by antagonizing endothelin.

Incidence of skin pigmentation disorders has been on the rise globally. This calls for safer and more effective topical skin lightening and freckle-removing products. In this study, we hypothesized that Soluble Pearl Extract (SPE) may possess endothelin antagonizing compounds with good skin whitening effects. (a) To determine the effect and mechanisms of SPE on ET-1-treated B16 melanoma cells. (b) To explore the cytotoxic effects of SPE on B16 melanoma cells. CCK-8 assay was performed to determine how SPE and ET-1 affect the proliferation rate of B16 melanoma cells, the NaOH lysis assay was conducted to quantify the content of melanin while the tyrosinase activity was determined by DOPA oxidation test. The mRNA and protein expression levels of TYR and TRP-1 were determined by qRT-PCR assay and Western blot assay, respectively. We found that SPE at 0.1 and 1μg/mL concentrations has no effect on the proliferation of the cells and 10nmol/L ET-1 promoted B16 melanoma cells proliferation. Notably, B16 melanoma cells treated with 10nmol/L ET-1 exhibited significantly higher melanin synthesis, tyrosinase activity, TYR, and TRP-1 mRNA expression levels compared with untreated cells. Of note, the effects of 10nmol/L ET-1 treatment were abolished with SPE in a dose-dependent manner. SPE inhibits endothelin thereby safely and effectively lightening lightens the skin by antagonizing endothelin. Moreover, SPE is safe and effective.

Isolation of proanthocyanidins from Pinus thunbergii needles and tyrosinase inhibition activity

In the present work, we investigated the anti-tyrosinase activity, mechanism and antioxidant activity of proanthocyanidins (PAs) isolated from Pinus thunbergii needles. The results showed that PAs mainly consisted of catechin/epicatechin and had a strong inhibitory effect on the monophenolase and diphenolase activity of tyrosinase. PAs could reduce the steady state activity of tyrosinase monophenolase while prolonging the reaction delay time in a dose-dependent manner. The inhibitory effect of PAs on tyrosinase diphenolase was reversible, with the IC50 value of 37.64 μg/mL. The inhibition kinetic analysis by Lineweaver-Burk plots showed that PAs were a mixed-type inhibitor of tyrosinase diphenolase, with inhibition constants KI and KIS of 29.92 μg/mL and 128.27 μg/mL, respectively. Further, determination of the metal chelating ability, scanning study, fluorescence quenching, and DOPA (dihydroxyphenylalanine) oxidation were used to study the potential inhibition mechanism of PAs on tyrosinase. The results confirmed that PAs could chelate with copper ions in the active site of tyrosinase to inhibit tyrosinase activity. Moreover, ABTS [2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)] and FRAP (ferric reducing antioxidant power) assay showed good antioxidant capacity of PAs. This study revealed the possibility of Pinus thunbergii needle PAs as a new tyrosinase inhibitor in the fields of food, medicine, and cosmetics industries.

Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action

ABSTRACT The aim of this study was to determine the effects of anti-wrinkle and skin-whitening of fermented black ginseng (FBG) in human subjects and to examine underlying biochemical mechanisms of action. A clinical study was performed to evaluate efficacy and safety using a 1% FBG cream formulation. Twenty-three subjects were recruited and instructed to apply control or FBG creams each on half of their face twice daily for 8 weeks. After 8 weeks, FBG cream significantly reduced the appearance of eye wrinkles compared to prior to exposure and control cream. Skin color was significantly brightened using FBG cream in comparison with a control cream. To determine the mechanism of actions involved in anti-wrinkle and skin-whitening effects various concentrations of FBG were applied to human fibroblast CCD-986sk and mouse melanoma B16F1 cells. Collagen synthesis in CCD-986sk cells was improved significantly at 1, 3, 10, or 30 µg/ml of FBG. At 30 µg/ml, FBG significantly inhibited (73%) collagenase, and matrix metalloproteinase-1 (MMP-1) compared to control. Tyrosinase activity and DOPA (3,4-dihydroxy-L-phenylalanine) oxidation were significantly decreased at all tested concentrations. Melanin production in B16F1 cells was concentration-dependently reduced from 15% to 60% by all concentrations of FBG. These results suggested that a 1% FBG cream exerted anti-wrinkle and skin-whitening effects.

Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action

ABSTRACT The aim of this study was to determine the effects of anti-wrinkle and skin-whitening of fermented black ginseng (FBG) in human subjects and to examine underlying biochemical mechanisms of action. A clinical study was performed to evaluate efficacy and safety using a 1% FBG cream formulation. Twenty-three subjects were recruited and instructed to apply control or FBG creams each on half of their face twice daily for 8 weeks. After 8 weeks FBG cream significantly reduced appearance of eye wrinkles compared to prior to exposure and control cream. Skin color was significantly brightened using FBG cream in comparison with control cream. To determine the mechanism of actions involved in anti-wrinkle and skin-whitening effects various concentrations of FBG were applied to human fibroblast CCD-986sk and mouse melanoma B16F1 cells. Collagen synthesis in CCD-986sk cells was improved significantly at 1, 3, 10, or 30 µg/ml of FBG. At 30 µg/ml, FBG significantly inhibited (73%) collagenase, and matrix metalloproteinase-1 (MMP-1) compared to control. Tyrosinase activity and DOPA (3,4-dihydroxy-L-phenylalanine) oxidation were significantly decreased at all tested concentrations. Melanin production in B16F1 cells was concentration-dependently reduced 15% to 60% by all concentrations of FBG. These results suggested that a 1% FBG cream exerted anti-wrinkle and skin-whitening effects.

The influence of iron on selected properties of synthetic pheomelanin

It is believed that while eumelanin plays photoprotective and antioxidant role in pigmented tissues, pheomelanin being more photoreactive could behave as a phototoxic agent. Although the metal ion-sequestering ability of melanin might be protective, transition metal ions present in natural melanins could affect their physicochemical properties. The aim of this research was to study iron binding by pheomelanin and analyze how such a binding affects selected properties of the melanin. Synthetic pheomelanin (CDM), prepared by enzymatic oxidation of DOPA in the presence of cysteine was analyzed by electron paramagnetic resonance (EPR) spectroscopy, spectrophotometry, chemical analysis, and time-resolved measurements of singlet oxygen phosphorescence. Iron broadened EPR signal of melanin and increased its optical absorption. Iron bound to melanin exhibited EPR signal at g = 4.3, typical for high-spin iron (III). Iron bound to melanin significantly altered the kinetics of melanin photodegradation, which in turn modified the accessibility and stability of the melanin–iron complexes as indicated by the release of iron from melanin induced by diethylenetriaminepentaacetic acid and KCN. Although bound to melanin iron little affects initial stages of photodegradation of CDM, the effect of iron becomes more pronounced at later stages of melanin photolysis.

Histidine residues at the copper-binding site in human tyrosinase are essential for its catalytic activities

Tyrosinase is a copper-binding enzyme involved in melanin biosynthesis. However, the detailed structure of human tyrosinase has not yet been solved, along with the identification of the key sites responsible for its catalytic activity. We used site-directed mutagenesis to identify the residues critical for the copper binding of human tyrosinase. Seven histidine mutants in the two copper-binding sites were generated, and catalytic activities were characterised. The tyrosine hydroxylase activities of the CuA site mutants were approximately 50% lower than those of the wild-type tyrosinase, while the dopa oxidation activities of the mutants were not significantly different from that of wild-type tyrosinase. By contrast, mutations at CuB significantly decreased both tyrosine hydroxylation and dopa oxidation activities, confirming that the catalytic sites for these two activities are at least partially distinct. These findings provide a useful resource for further structural determination and development of tyrosinase inhibitors in the cosmetic and pharmaceutical industries.

The Thiol-Rich Interlayer in the Shell/Core Architecture of Mussel Byssal Threads.

The mussel byssus thread is an extremely tough core-shelled fiber that dissipates substantial amounts of energy during tensile loading. The mechanical performance of the shell is critically reliant on 3,4-dihydroxyphenylalanine's (Dopa) ability to form reversible iron-catecholate complexes at pH 8. However, the formation of these coordinate cross-links is undercut by Dopa's oxidation to Dopa-quinone, a spontaneous process at seawater conditions. The large mechanical mismatch between the cuticle and the core lends itself to further complications. Despite these challenges, the mussel byssus thread performs its tethering function over long periods of time. Here, we address these two major questions: (1) how does the mussel slow/prevent oxidation in the cuticle, and (2) how is the mechanical mismatch at the core/shell interface mitigated? By combining a number of microscopy and spectroscopy techniques we have discerned a previously undescribed layer. Our results indicate this interlayer is thiol rich and thus will be called the thiol-rich interlayer (TRL). We propose the TRL serves as a long-lasting redox reservoir as well as a mechanical barrier.

Effect of the Stromal Vascular Fraction on Changes in Melanin Formation in B16 Cells Treated by IBMX.

To investigate the effect of the stromal vascular fraction (SVF) on changes in melanin formation and tyrosinase activity in B16 cells treated by 3-isobutyl-1 methylxanthine (IBMX) and to explore the mechanism of SVF-mediated inhibition of pigmentation. We co-cultured extracted SVFs and B16 cells treated with IBMX in a certain proportion, and the marker molecule HMB-45 was detected by immunochemistry. Melanin content was determined by NaOH lysis. Activity of tyrosinase was measured by the DOPA oxidation method. HMB-45 was commonly expressed in B16 cells induced by IBMX. After the addition of SVFs, the expression of HMB-45 decreased significantly and positively correlated with increases in SVFs. After the induction of B16 cells by IBMX, melanin content increased significantly. However, melanin decreased after SVF and B16 co-culturing; the effect was more substantial with the increase and decrease in SVFs, and the activity of tyrosinase decreased. SVFs inhibit the production of melanin and reduce the activity of tyrosinase, possibly providing a new breakthrough for the treatment of pigment disorders. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Anti-melanogenesis activity of Ecklonia cava extract cultured in tanks with magma seawater of Jeju Island

Ecklonia cava is popular in Korea as a marine functional materials. E. cava is generally collected and used on the coast of Jeju Island. However, the continuous use of collected natural E. cava may be limited because difficult to secure throughout the year and may be exposed to environmental pollution. Jeju magma seawater (MSW) was known to be significant advantages such as safety, cleanness, stability, and functional improvement. Attempts have been reported on application of MSW to the culturing of macro- and microalgae and showed improved results. Thus, the objective of the present study was to explore the anti-melanogenesis activity of brown seaweed E. cava (E. cava cultured with MSW [MSWE]) extract cultured in tanks with MSW of Jeju Island to evaluate the possibility of cosmeceutical industrial application. MSWE extract showed the higher polyphenolic and dieckol contents than natural E. cava (NE) extract. Anti-melanogenesis activity of MSWE extract and NE extract are tested and compared using tyrosinase and dihydroxyphenylalanine (DOPA) oxidation inhibition assay. MSWE extracts evidenced more effective tyrosinase and DOPA oxidation inhibition activity than that of the NE extracts and the commercial whitening agent, arbutin. MSWE extracts also markedly inhibited melanin synthesis and decreased the expression of melanogenesis-related protein in α-melanocyte stimulating hormone-stimulated B16F10 melanoma cells without cytotoxicity. These results suggest that MSW cultivation process would be more effective in releasing bioactive compounds with whitening effect from seaweed such as E. cava at an industrial scale. Key words: anti-melanogenesis activity; cultivation; Ecklonia cava; Jeju magma seawater; polyphenolic content

A mussel polyphenol oxidase-like protein shows thiol-mediated antioxidant activity

Marine mussels adhere underwater to a variety of substrates using adhesive proteins with post-translationally modified amino acids, such as 3,4-dihydroxyphenylalanine (DOPA) residues, as a key chemical signature. DOPA can auto-oxidize easily in seawater reducing the adhesion strength, but contributing to subsequent cohesion (cross-linking) of the underlying proteins. To maintain both reduced and oxidized forms of DOPA with corresponding adhesion and cohesion properties, strict redox regulation is necessary for mussel underwater adhesion. In this study, a full-length polyphenol oxidase-like protein (PPOL) from Mytilus galloprovincialis was identified after screening of a mussel foot cDNA library using different degenerated PCR primers. The recombinant PPOL (rPPOL) was successfully produced in Escherichia coli. The rPPOL exhibits thiol-dependent antioxidant activity suppressing DOPA oxidation. This finding provides insights into how DOPA chemistry could be regulated and presumably inspires future applications of DOPA-mediated adhesion materials.

Propiedades Adhesivas Húmedas de la Proteína del Pie de Mejillones Verdes Asiático (Perna viridis) Pvfp-5: Una Base Adhesiva Subacuática

Los mejillones verdes asiáticos (Perna viridis) son bivalvos que se adhieren firmemente a las rocas en las costas intermareales golpeadas por las olas a través de una secreción proteica. Los mejillones de P. viridis siguen una secreción de proteínas adhesivas regulada en el tiempo, donde la proteína del pie-5 de P. viridis (Pvfp-5) fue identificada como la primera proteína que se secreta durante la formación de la placa adhesiva. El alto contenido de aminoácido catecólico 3,4-dihidroxi-L-fenilalanina (DOPA) (~11% en moles) y cisteína (CYS) (~15% en moles) en Pvfp-5 y su localización cerca de la interfaz placa-sustrato provocó la especulación de que la proteína de vanguardia Pvfp-5 desempeña un papel clave como imprimación adhesiva en la adhesión bajo el agua de los mejillones de P. viridis. El aparato de fuerza de superficie (SFA) se usó para probar las propiedades adhesivas de Pvfp-5 a escala nanométrica, donde se investigó la adhesión húmeda dependiente del pH y la actividad antioxidante de Pvfp-5 purificado y extraído. El estudio reveló que Pvfp-5 con su alto contenido de DOPA y CYS mantiene la adhesión incluso a un pH más alto al superar la oxidación espontánea de DOPA a quinona. Los resultados de SFA son consistentes con la función aparente de que Pvfp-5 actúa como imprimación adhesiva, superando las fuerzas de hidratación repulsivas al desplazar el agua unida a la superficie y generando una adhesión superficial fuerte y duradera. Nuestros hallazgos revelan conocimientos a escala molecular que deberían ser relevantes e impactar en las ciencias de los materiales al desarrollo de la nueva generación de adhesivos, recubrimientos y pegamentos resistentes a la humedad para aplicaciones biomédicas, terapéuticas y antiincrustantes.

Chemical oxidants affect byssus adhesion in the highly invasive fouling mussel Limnoperna fortunei

Biofouling by the invasive mussel species Limnoperna fortunei has caused severe negative consequences in various freshwater ecosystems, but there is still a lack of effective antifouling strategies for this species, particularly in drinking water treatment systems where many existing strategies cannot be used. Chemical oxidants have been proposed to potentially control fouling mussels by influencing 3,4‑dihydroxyphenylalanine oxidation involved in byssus adhesion. To test this potential control strategy, L. fortunei adults were exposed to four oxidants: sodium hypochlorite (NaClO), potassium permanganate (KMnO4), hydrogen peroxide (H2O2) and chloramine T (CAT) at concentrations of 0.5, 1.0, 3.0 and 5.0 mg L−1 for one week. The results showed that low concentrations of KMnO4 stimulated foot protein secretion, which was beneficial to byssus production (number and length). NaClO and H2O2, but not KMnO4 and CAT, significantly inhibited byssus production and reduced breaking force, causing an increased byssus shedding rate. However, only NaClO dissolved byssus and altered the failure location from the byssal thread to adhesive plaque, even when exposed at low concentrations, showing its great impacts on byssus adhesion. Further analysis of polyphenoloxidase activities and gene expression profiles of LfBP-1, LfFP-2 and LfBP-3 revealed that chemical oxidants affected byssus adhesion by altering Dopa oxidation and foot protein gene expressions. This study, therefore, suggests that a low concentration of NaClO can be used as an alternative and environmentally friendly chemical for controlling L. fortunei biofouling by weakening byssus adhesion.