Photoredox phase engineering of transition metal dichalcogenides.

Crystallographic phase engineering plays an important part in the precise control of the physical and electronic properties of materials. In two-dimensional transition metal dichalcogenides (2D TMDs), phase engineering using chemical lithiation with the organometallization agent n-butyllithium (n-BuLi), to convert the semiconducting 2H (trigonal) to the metallic 1T (octahedral) phase, has been widely explored for applications in areas such as transistors, catalysis and batteries1-15. Although this chemical phase engineering can be performed at ambient temperatures and pressures, the underlying mechanisms are poorly understood, and the use of n-BuLi raises notable safety concerns. Here we optically visualize the archetypical phase transition from the 2H to the 1T phase in mono- and bilayer 2D TMDs and discover that this reaction can be accelerated by up to six orders of magnitude using low-power illumination at 455 nm. We identify that the above-gap illumination improves the rate-limiting charge-transfer kinetics through a photoredox process. We use this method to achieve rapid and high-quality phase engineering of TMDs and demonstrate that this methodology can be harnessed to inscribe arbitrary phase patterns with diffraction-limited edge resolution into few-layer TMDs. Finally, we replace pyrophoric n-BuLi with safer polycyclic aromatic organolithiation agents and show that their performance exceeds that of n-BuLi as a phase transition agent. Our work opens opportunities for exploring the in situ characterization of electrochemical processes and paves the way for sustainably scaling up materials and devices by photoredox phase engineering.

Risk Factors and Clinical Outcomes of Osteotomy Plane Violation by D-Hole Screws in Medial Open Wedge High Tibial Osteotomy: A Simulation and Comparative Study.

Background and Objectives: Stable fixation is essential for successful healing after medial open wedge high tibial osteotomy (MOWHTO) to minimize the risk of non-union and correction loss. In Asians, potential complications such as D-hole screw osteotomy plane violation (D-hole violation) and inadequate plate fitting arise due to improper plate size. This study aimed to evaluate the risk factors for D-hole violation and compare the conventional anatomic (CA) plate with an individualized anatomic (IA) plate in MOWHTO procedures. Materials and Methods: A simulation study on D-hole violation using the CA plate was conducted, involving preoperative radiographs and CT scans of 64 lower extremities from 47 MOWHTO patients. Additionally, a randomized controlled study compared CA and IA plates in MOWHTO procedures with 34 patients (17 in the CA plate group; 18 in the IA plate group). Patient demographics, patient-reported outcome measures (PROMs), and radiological measures were analyzed. Results: In the simulation study, the rates of D-hole violation ranged from 20.3% to 59.4%, with an increase observed as the plate was distalized from 5 mm to 10 mm away from the joint line. Short stature was identified as an independent risk factor for D-hole violation (p < 0.001), with a cutoff value of 155.3 cm. In the randomized controlled study, no significant difference in PROMs and D-hole violation was observed between the CA plate and IA plate groups. However, the IA plate group showed better plate fitting compared to the CA plate group (p = 0.041). Conclusions: This study identified a high risk of D-hole screw osteotomy plane violations in MOWHTO procedures, particularly when the plate is positioned more distally and in individuals with a stature below 155.3 cm. It also revealed that individualized plates provide better tibial fitting compared to conventional anatomic plates, particularly in Asian populations where tibial morphology tends to be shorter than in Western populations. Therefore, evaluating patient stature and selecting tailored plates are essential to optimize plate positioning and minimize plate-related complications in MOWHTO procedures.

Differences in Facial Expressions between Spontaneous and Posed Smiles: Automated Method by Action Units and Three-Dimensional Facial Landmarks.

Research on emotion recognition from facial expressions has found evidence of different muscle movements between genuine and posed smiles. To further confirm discrete movement intensities of each facial segment, we explored differences in facial expressions between spontaneous and posed smiles with three-dimensional facial landmarks. Advanced machine analysis was adopted to measure changes in the dynamics of 68 segmented facial regions. A total of 57 normal adults (19 men, 38 women) who displayed adequate posed and spontaneous facial expressions for happiness were included in the analyses. The results indicate that spontaneous smiles have higher intensities for upper face than lower face. On the other hand, posed smiles showed higher intensities in the lower part of the face. Furthermore, the 3D facial landmark technique revealed that the left eyebrow displayed stronger intensity during spontaneous smiles than the right eyebrow. These findings suggest a potential application of landmark based emotion recognition that spontaneous smiles can be distinguished from posed smiles via measuring relative intensities between the upper and lower face with a focus on left-sided asymmetry in the upper region.

Inhibition of platelet aggregation and thrombosis by indole alkaloids isolated from the edible insect Protaetia brevitarsis seulensis (Kolbe).

Protaetia brevitarsis seulensis (Kolbe) has been temporarily registered as a food material by the Ministry of Food and Drug Safety of Korea (MFDS). The current study aimed to discover small antithrombotic molecules from this edible insect. Five indole alkaloids, 5-hydroxyindolin-2-one (1), (1R,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (2), (1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (3), (3S)-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (4) and L-tryptophan (5), were isolated from the insect. Among them, compounds 1 and 2 prolonged aPTT and PT and impaired thrombin and FXa generation on HUVEC surface. Moreover, these compounds inhibited platelet aggregation. Antithrombotic effects of compounds 1 and 2 were further confirmed in pre-clinical models of pulmonary embolism and arterial thrombosis. Collectively, these results demonstrated that compounds 1 and 2 could be effective antithrombotic agents and serve as new scaffolds for the development of antithrombotic drug.

Decolorization of textile dyes in an air-lift bioreactor inoculated with Bjerkandera adusta OBR105.

A new decolorizing white-rot fungus, OBR105, was isolated from Mount Odae in South Korea and identified by the morphological characterization of its fruit body and spores and partial 18s rDNA sequences. The ligninolytic enzyme activity of OBR105 was studied to characterize their decolorizing mechanism using a spectrophotometric enzyme assay. For the evaluation of the decolorization capacity of OBR105, the isolate was incubated in an erlenmeyer flask and in an airlifte bioreator with potato dextrose broth (PDB) medium supplemented with each dye. In addition, the decolorization efficiency of real textile wastewater was evaluated in an airlift bioreactor inoculated with the isolate. The isolate was identified as Bjerkandera adusta and had ligninolytic enzymes such as laccase, lignin peroxidase (LiP), and Mn-dependent peroxidase (MnP). Its LiP activity was higher than its MnP and laccase activities. B. adusta OBR105 successfully decolorized reactive dyes (red 120, blue 4, orange 16, and black 5) and acid dyes (red 114, blue 62, orange 7, and black 172). B. adusta OBR105 decolorized 91-99% of 200 mg L-1 of each dye (except acid orange 7) within 3 days in a PDB medium at 28°C, pH 5, and 150 rpm. This fungus decolorized only 45% of 200 mg L-1 acid orange 7 (single azo-type dye) within 3 days, and the decolorization efficiency did not increase by prolonging the cultivation time. In the air-lift bioreactor, B. adusta OBR105 displayed a high decolorization capacity, greater than 90%, for 3 acid dyes (red 114, blue 62, and black 172) and 1 reactive dye (blue 4) within 10-15 h of treatment. B. adusta OBR105 could decolorize real textile wastewater in the air-lift bioreactor. This result suggests that an air-lift reactor employing B. adusta OBR105 is a promising bioreactor for the treatment of dye wastewater.

Decolorization of acid, disperse and reactive dyes by Trametes versicolor CBR43.

The mycoremediation has been considered as a promising method for decolorizing dye wastewater. To explore new bioresource for mycoremediation, a new white-rot fungus that could decolorize various dyes commonly used in textile industries was isolated, and its ligninolytic enzyme activity and decolorization capacity were characterized. The isolated CBR43 was identified as Trametes versicolor based on the morphological properties of its fruit body and spores, as well as through partial 18S rDNA gene sequences. Isolated CBR43 displayed high activities of laccase and Mn-dependent peroxidase, whereas its lignin peroxidase activity was relatively low. These ligninolytic enzyme activities in potato dextrose broth (PDB) medium were enhanced by the addition of yeast extract (1-10 g L-1). In particular, lignin peroxidase activity was increased more than 5 times in the PDB medium amended with 10 g L-1 of yeast extract. The CBR43 decolorized more than 90% of 200 mg L-1 acid dyes (red 114, blue 62 and black 172) and reactive dyes (red 120, blue 4, orange 16 and black 5) within 6 days in the PDB medium. CBR43 decolorized 67% of 200 mg L-1 acid orange 7 within 9 days. The decolorization efficiencies for disperse dyes (red 1, orange 3 and black 1) were 51-80% within 9 days. The CBR43 could effectively decolorize high concentrations of acid blue 62 and acid black 172 (500-700 mg L-1). The maximum dye decolorization rate was obtained at 28°C, pH 5, and 150 rpm in the PDB medium. T. versicolor CBR43 had high laccase and Mn-dependent peroxidase activities, and could decolorize a wide variety of dyes such as acid, disperse and reactive textile dyes. This fungus had decolorizing activities of azo-type dyes as well as anthraquinone-type dyes. T. versicolor CBR43 is one of promising bioresources for the decolorization of textile wastewater including various dyes.

Amphiphilic Graft Copolymers as a Versatile Binder for Various Electrodes of High-Performance Lithium-Ion Batteries.

It is known that grafting one polymer onto another polymer backbone is a powerful strategy capable of combining dual benefits from each parent polymer. Thus amphiphilic graft copolymer precursors (poly(vinylidene difluoride)-graft-poly(tert-butylacrylate) (PVDF-g-PtBA)) have been developed via atom transfer radical polymerization, and demonstrated its outstanding properties as a promising binder for high-performance lithium-ion battery (LIB) by using in situ pyrolytic transformation of PtBA to poly(acrylic acid) segments. In addition to its superior mechanical properties and accommodation capability of volume expansion, the Si anode with PVDF-g-PtBA exhibits the excellent charge and discharge capacities of 2672 and 2958 mAh g(-1) with the capacity retention of 84% after 50 cycles. More meaningfully, the graft copolymer binder shows good operating characteristics in both LiN0.5 M1.5 O4 cathode and neural graphite anode, respectively. By containing such diverse features, a graft copolymer-loaded LiN0.5 M1.5 O4 /Si-NG full cell has been successfully achieved, which delivers energy density as high as 546 Wh kg(-1) with cycle retention of ≈70% after 50 cycles (1 C). For the first time, this work sheds new light on the unique nature of the graft copolymer binders in LIB application, which will provide a practical solution for volume expansion and low efficiency problems, leading to a high-energy-density lithium-ion chemistry.

Caffeoyl glucosides from Nandina domestica inhibit LPS-induced endothelial inflammatory responses.

Endothelial dysfunction is a key pathological feature of many inflammatory diseases, including sepsis. In the present study, a new caffeoyl glucoside (1) and two known caffeoylated compounds (2 and 3) were isolated from the fruits of Nandina domestica Thunb. (Berberidaceae). The compounds were investigated for their effects against lipopolysaccharide (LPS)-mediated endothelial inflammatory responses. At 20 µM, 1 and 2 inhibited LPS-induced hyperpermeability, adhesion, and migration of leukocytes across a human endothelial cell monolayer in a dose-dependent manner suggesting that 1 and 2 may serve as potential scaffolds for the development of therapeutic agents to treat vascular inflammatory disorders.

Effects of Quality of Integrity on Clinical and Structural Outcomes of Rotator Cuff Repair: A Retrospective Cohort Study of 504 Cases.

BACKGROUND: The clinical implications of structural integrity have been a subject of long debate. The oversimplified binary categorization of structural integrity into either healing or retear, along with faulty preoperative baselines for comparison, may contribute to the controversy. PURPOSE: To determine how the quality of structural integrity in a repaired cuff tendon affects both clinical and structural outcomes by dividing the patients into groups based on integrity and using the immediate postoperative baseline (time zero). STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 504 patients with a full-thickness rotator cuff tear who underwent arthroscopic rotator cuff repair and were followed up for at least a year with magnetic resonance imaging (MRI) were included. The quality of structural integrity was graded using the Sugaya classification. To evaluate clinical outcomes, pain, range of motion, strength, functional scores, and overall satisfaction and function were used for within- and between-group analyses at the last follow-up. For the assessment of structural outcomes, the Goutallier classification for fatty infiltration (FI) and the tangent sign, occupation ratio, and normalized cross-sectional area for muscle atrophy (MA) were used. The baselines for these structural measurements were both the preoperative and the time-zero MRI scans. RESULTS: The mean clinical follow-up period was 31.8 ± 27.5 months, and the MRI follow-up period was 10.9 ± 5.3 months. There were 178 (35.3%), 228 (45.2%), 58 (11.5%), 14 (2.8%), and 26 (5.2%) shoulders with Sugaya grades 1, 2, 3, 4, and 5, respectively. Regardless of structural integrity, all clinical outcomes at a mean follow-up of 31.8 months after repair significantly improved compared with those before repair. Only in shoulders with Sugaya grade 1 did the FI of the supraspinatus muscle improve significantly from baseline. FI of the infraspinatus muscle did not change significantly in those with grades 1 and 2 but worsened in those with grades 3 and 5. MA measured using the occupation ratio improved significantly in shoulders with Sugaya grades 1 and 2 but declined in those with grade 5. CONCLUSION: This study established a correlation between improved structural integrity of the repaired cuff tendon and enhanced structural outcomes in rotator cuff muscles. Furthermore, the findings revealed that both FI and MA could be reversed in patients exhibiting high-quality structural integrity. However, these structural improvements were not mirrored in the clinical outcomes.

Metal Films on Two-Dimensional Materials: van der Waals Contacts and Raman Enhancement.

Electronic devices based on two-dimensional (2D) materials will need ultraclean and defect-free van der Waals (vdW) contacts with three-dimensional (3D) metals. It is therefore important to understand how vdW metal films deposit on 2D surfaces. Here, we study the growth and nucleation of vdW metal films of indium (In) and non-vdW metal films of gold (Au), deposited on 2D MoS2 and graphene. In follows a 2D growth mode in contrast to Au that follows a 3D growth mode. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to image the morphology of metal clusters during growth and quantify the nucleation density. As compared to Au, In atoms exhibit nearly 50 times higher diffusivity (3.65 × 10-6 µm-2 s-1) and half the nucleation density (64.9 ± 2.46 µm-2), leading to larger grain sizes (∼60 nm for 5 nm In on monolayer MoS2). The grain size of In can be further increased by reducing the 2D surface roughness, while the grain size for Au is limited by its high nucleation density due to the creation of interface defects during deposition. The vdW gap between In and MoS2 and graphene leads to strong enhancement (>103) in their Raman signal intensity due to localized surface plasmon resonance. In the absence of a vdW gap, the plasmon-mediated enhancement in Raman does not occur.

Surface engineering of sponge-like silicon particles for high-performance lithium-ion battery anodes.

Surface engineering of sponge-like Si particles is necessary to alleviate the large volume expansion of Si during the lithiation-delithiation process and to mitigate the unwanted interfacial reactions upon cycling. The sponge-like Si structuring and introduction of double layers consisting of carbon and polyimide enabled us to make high performance Si anode materials exhibiting a high specific capacity and highly stable cycling.

Nonporous Oxide-Terminated Multicomponent Bulk Anode Enabling Energy-Dense Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are emerging as power sources for large-scale storage owing to their abundant and inexpensive sodium (Na) source, but their limited energy density hinders their commercialization. High-capacity anode materials, such as antimony (Sb), which are potential energy boosters for SIBs, suffer from battery degradation owing to large-volume-changes and structural instability. The rational design of bulk Sb-based anodes to enhance the initial reversibility and electrode density inevitably requires atomic- and microscale-considered internal/external buffering or passivation layers. However, unsuitable buffer engineering causes electrode degradation and lowers energy density. Herein, the rationally designed intermetallic inner and outer oxide buffers for bulk Sb anodes are reported. The two chemistries in the synthesis process provide an atomic-scale aluminum (Al) buffer within the dense microparticles and an external mechanically stabilizing dual oxide layer. The prepared nonporous bulk Sb anode maintained excellent reversible capacity at a high current density and Na-ion full battery evaluations with Na3V2(PO4)3 (NVP) showing negligible capacity decay over 100 cycles. The demonstrated buffer designs for commercially favorable micro-sized Sb and intermetallic AlSb shed light on the stabilization of high-capacity or large-volume-change electrode materials for various metal-ion rechargeable batteries.

Helical silicon/silicon oxide core-shell anodes grown onto the surface of bulk silicon.

We demonstrate a simple route for preparing Si/SiO(x) urchin-like structures in which Si/SiO(x) core-shell nanocoils protruded out from the surface of bulk Si, via high-temperature annealing of Pt-decorated Si powders. The carbon-coated urchin-like anodes with micro- and nanostructured composite exhibit a significantly improved electrochemical performance with a high specific capacity of 1600 mAh/g and a superior cycling performance of 70 cycles at a rate of 0.2 C due to the nanocoil conformation and SiO(x) buffer layer. More importantly, the composite results in a significantly enhanced the volumetric capacity with ∼3780 mAh/cc, compared to bulk Si (∼2720 mAh/cc) after fully lithiation to 0 V.

Chemical-assisted thermal disproportionation of porous silicon monoxide into silicon-based multicomponent systems.

Under the surface: Ag nanoparticles are deposited onto the surface of commercially available SiO particles, and subsequent chemical etching results in the formation of nanoporous SiO without changing the chemical and physical properties of the original SiO. Moreover, chemical-assisted thermal annealing produces a shape-preserving Si-based multicomponent system, which exhibits high-performance electrochemical properties.

Selective neurodegeneration of the hippocampus caused by chronic cerebral hypoperfusion: F-18 FDG PET study in rats.

BACKGROUND: Chronic cerebral hypoperfusion (CCH) is known to induce Alzheimer's disease (AD) pathology, but its mechanism remains unclear. The purpose of this study was to identify the cerebral regions that are affected by CCH, and to evaluate the development of AD pathology in a rat model of CCH. METHODS: A rat model of CCH was established by bilaterally ligating the common carotid arteries in adult male rats (CCH group). The identical operations were performed on sham rats without arteries ligation (control group). Regional cerebral glucose metabolism was evaluated at 1 and 3 months after bilateral CCA ligation using positron emission tomography with F-18 fluorodeoxyglucose. The expression levels of amyloid ß40 (Aß40), amyloid ß42 (Aß42), and hyperphosphorylated tau were evaluated using western blots at 3 months after the ligation. Cognitive function was evaluated using the Y-maze test at 3 months after the ligation. RESULTS: At 1 month after the ligation, cerebral glucose metabolism in the entorhinal, frontal association, motor, and somatosensory cortices were significantly decreased in the CCH group compared with those in the control group. At 3 months after the ligation, cerebral glucose metabolism was normalized in all regions except for the anterodorsal hippocampus, which was significantly decreased compared with that of the control group. The expression of Aß42 and the Aß42/40 ratio were significantly higher in the CCH group than those in the control group. The phosphorylated-tau levels of the hippocampus in the CCH group were significantly lower than those in the control group. Cognitive function was more impaired in the CCH group than that in the control group. CONCLUSION: Our findings suggest that CCH causes selective neurodegeneration of the anterodorsal hippocampus, which may be a trigger point for the development of AD pathology.

Antioxidant and antimicrobial efficacy of a biflavonoid, amentoflavone from Nandina domestica in vitro and in minced chicken meat and apple juice food models.

A biflavonoid, amentoflavone isolated from Nandina domestica and characterized by NMR spectral-data analyses was assessed for its antioxidant, and antibacterial potential in vitro and in food-model systems. Amentoflavone exhibited potent antioxidant ability (19.21-75.52%) on scavenging DPPH, ABTS, superoxide, and hydroxyl radicals. Fluorescent images confirmed bacterial membrane depolarization of both the tested pathogens Staphylococcus aureus and Escherichia coli, with a significant reduction in cell viabilities at their respective MIC of 62.5 and 125 µg/mL. Increasing rates of membrane permeability observed in 260 nm-absorbing material, potassium ion, extracellular ATP, and relative electrical conductivity assays confirmed antibacterial mechanistic role of amentoflavone as also evidenced by microscopic studies of SEM and TEM. There was a marked inhibitory effect of amentoflavone with a significant reduction in cell counts of S. aureus and E. coli in minced chicken and apple juice at 4 °C, thus suggesting its nutritional enhancing efficacy as a natural antioxidant and antimicrobial agent.

The effect of chronic cerebral hypoperfusion on the pathology of Alzheimer's disease: A positron emission tomography study in rats.

Cerebrovascular disease is a potential risk factor for Alzheimer's disease (AD). Although acute cerebral hypoperfusion causes neuronal necrosis and infarction, chronic cerebral hypoperfusion induces apoptosis in neurons, but its effects on the cognitive impairment are not clear. The purpose of this study was to evaluate the effects of chronic cerebral hypoperfusion on AD pathology and cerebral glucose metabolism. A model of chronic cerebral hypoperfusion was established by ligating the common carotid arteries bilaterally in adult male rats (CAL group). Sham-operated rats underwent the same procedures without artery ligation (control group). At 12 weeks after ligation, expression levels of amyloid-ß (Aß) and hyperphosphorylated tau (p-tau), as well as the regional cerebral glucose metabolism, were evaluated using Western blots and positron emission tomography with fluorine-18 fluorodeoxyglucose, respectively. The expression levels of Aß in the frontal cortex and hippocampus and of p-tau in the temporal cortex were significantly higher in the CAL group than those in the control group. The cerebral glucose metabolism of the amygdala, entorhinal cortex, and hippocampus was significantly decreased in the CAL group compared to that in the control. These results suggest that chronic cerebral hypoperfusion can induce AD pathology and may play a significant role in AD development.

Controlled Synthesis of Sulfur-Rich Polymeric Selenium Sulfides as Promising Electrode Materials for Long-Life, High-Rate Lithium Metal Batteries.

High-energy lithium/sulfur (Li/S) batteries still suffer from unsatisfactory cycle life and poor rate capability caused by the polysulfides shuttle and insulating nature of S cathodes. Here, we report our findings in the controlled synthesis of selenium (Se)-containing S-rich co-polymers of various compositions as novel cathode materials through a facile inverse vulcanization of S with selenium disulfide (SeS2) and 1,3-diisopropenylbenzene (DIB) as co-monomers. Nuclear magnetic resonance and X-ray photoelectron spectroscopy results show that divinyl functional groups of DIB were chemically cross-linked with S/SeS2 chain radicals through a ring-opening polymerization. The newly formed bonds of C-S, C-Se, and S-Se in novel S-SeS2-DIB co-polymers effectively alleviate the shuttle effects of polysulfides/polyselenides. Furthermore, various electrochemical techniques confirm the positive roles of Se-containing co-polymers in enhancing the electrode reaction kinetics and the formation of stable solid electrolyte interphase layer with low charge-transfer resistance, leading to improved high-rate performances. The as-synthesized co-polymer was then infiltrated into well-interconnected, porous nanocarbon networks (Ketjenblack EC600JD, KB600) to provide effective paths for the fast electron transport. Due to the synergistic combination of chemical and physical confinement of the reaction intermediates during cycling, good reversibility for 500 cycles with a low decay rate of 0.0549% per cycle was achieved at 1000 mA g-1. These encouraging results suggest that the combination of chemical incorporation of SeS2 into S-rich co-polymer and the physical confinement of carbon networks is a promising strategy for advancing Li/S batteries and their viability for practical applications.

Quinoxaline-, dopamine-, and amino acid-derived metabolites from the edible insect Protaetia brevitarsis seulensis.

Edible insects have been reported to produce metabolites showing various pharmacological activities, recently emerging as rich sources of health functional food. In particular, the larvae of Protaetia brevitarsis seulensis (Kolbe) have been used as traditional Korean medicines for treating diverse diseases, such as breast cancer, inflammatory disease, hepatic cancer, liver cirrhosis, and hepatitis. However, only few chemical investigations were reported on the insect larvae. Therefore, the aim of this study was to discover and identify biologically active chemical components of the larvae of P. brevitarsis seulensis. As a result, a quinoxaline-derived alkaloid (1) was isolated, which was not reported previously from natural sources. In addition, other related compounds (2, 4-10, 15, 16) were also encountered for the first time from the larvae. The structures of all the isolated compounds were established mainly by analysis of HRESIMS, NMR, and electronic circular dichroism data. Compound 5 exhibited inhibition of tyrosinase with IC50 value of 44.8 µM.

Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase.

In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.