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Hyunsu Do, Eungsu Kang, Byeongseon Yang, Hyung Joon Cha, Yoo Seong Choi
Tyrosinase efficiently catalyzes the ortho-hydroxylation of monophenols and the oxidation of diphenols without any additional cofactors. Although it is of significant interest for the biosynthesis of catechol derivatives, the rapid catechol oxidase activity and inactivation of tyrosinase have hampered its practical utilization as a monophenol monooxygenase. Here, we prepared a functional tyrosinase that exhibited a distinguished monophenolase/diphenolase activity ratio (V max mono/ V max di = 3.83) and enhanced catalytic efficiency against L-tyrosine (k cat  = 3...
December 8, 2017: Scientific Reports
Bonggi Lee, Kyoung Mi Moon, Bong-Seon Lee, Ju-Hye Yang, Kwang Il Park, Won-Kyung Cho, Jin Yeul Ma
Many skin-whitening compounds target tyrosinase because it catalyzes two rate-limiting steps in melanin synthesis. Although many tyrosinase inhibitors are currently available for a skin-whitening purpose, undesirable adverse effects are also reported. Thus, numerous efforts have been made to develop safer tyrosinase inhibitors from natural products. In line with this, we tested fifty flavonoids, a group of naturally occurring antioxidants and metal chelators, and screened swertiajaponin as the strongest tyrosinase inhibitor in cell-free experiments...
November 10, 2017: Oncotarget
Jianmin Chen, Weiyue Huang, Ziyao Huang, Shiqi Liu, Yaling Ye, Qinglian Li, Meiping Huang
Dissolving microneedles (MNs) offered a simple, minimally invasive method for meloxicam (MX) delivery to the skin. However, the fabrication of dissolving MNs still faced some challenges, such as significant time consumption, loss of drug activity, and difficulty in regulating MN drug loading. To address these issues, we developed the tip-dissolving (TD) MNs. Several kinds of drugs were encapsulated successfully, and the quantity of MX ranged from 37.23 ± 8.40 to 332.53 ± 13.37 μg was precisely controlled...
December 7, 2017: AAPS PharmSciTech
Małgorzata Pająk, Marianna Kańska
The kinetic (KIE) and solvent (SIE) isotope effect methods were used to investigate the mechanism of enzymatic hydroxylation of halogenated derivatives of l-tyrosine to l-DOPA catalyzed by the enzyme tyrosinase (EC The values of deuterium KIE and SIE were obtained using the non-competitive method with spectrophotometric measurements. The Lineweaver-Burk plots were used for determination of the inhibition mode of 3'-iodo-l-tyrosine. Based upon kinetic effects values the mechanism of action of enzyme tyrosinase was proposed...
2017: Journal of Radioanalytical and Nuclear Chemistry
Michael T Ringel, Gerald Draeger, Thomas Brüser
Pyoverdines are important siderophores that guarantee iron supply to important pathogenic and non-pathogenic pseudomonads in host habitats. A key characteristic of all pyoverdines is the fluorescent dihydroxyquinoline group that contributes two ligands to the iron complexes. Pyoverdines are derived from the non-ribosomally synthesized peptide ferribactin and their fluorophore is generated by periplasmic oxidation and cyclization reactions of D-tyrosine and L-diaminobutyric acid. The formation of the fluorophore is known to be driven by the periplasmic tyrosinase PvdP...
December 5, 2017: Journal of Biological Chemistry
Surabhi Dayal, Priyadarshini Sahu, Manoj Yadav, V K Jain
Introduction: Trichloroacetic Acid (TCA) is a versatile peeling agent for treatment of melasma. However, Post-Inflammatory Hyperpigmentation (PIH) is reported to be the most common side-effect associated with TCA peel. Topical Ascorbic Acid (AA) due to its effect as antioxidant and tyrosinase inhibitor helps to prevent PIH and maintains the response. Aim: To assess the clinical efficacy, safety and reduction in Melasma Quality of Life (MELASQOL) on combining 20% TCA peel with 5% ascorbic acid cream in epidermal melasma...
September 2017: Journal of Clinical and Diagnostic Research: JCDR
Bonggi Lee, Kyoung Mi Moon, Jong Seung Lim, Yeojin Park, Do Hyun Kim, Sujin Son, Hyoung Oh Jeong, Dae Hyun Kim, Eun Kyeong Lee, Ki Wung Chung, Hye Jin An, Pusoon Chun, Arnold Y Seo, Ju-Hye Yang, Bong-Seon Lee, Jin Yeul Ma, Won-Kyung Cho, Hyung Ryong Moon, Hae Young Chung
Tyrosinase is a key player in ultraviolet-induced melanogenesis. Because excessive melanin accumulation in the skin can induce hyperpigmentation, the development of tyrosinase inhibitors has attracted attention in cosmetic-related fields. However, side effects including toxicity and low selectivity have limited the use of many tyrosinase inhibitors in cosmetics. We synthesized 12 novel 2-(substituted benzylidene)malononitrile derivatives and investigated their anti-melanogenic activities. Of these 12 compounds, 2-(3, 4-dihydroxy benzylidene)malononitrile (BMN11) exhibited the strongest inhibitory activity against tyrosinase (IC50 = 17...
October 31, 2017: Oncotarget
Liyan Jiang, Di Wang, Yongfeng Zhang, Junyang Li, Zhiping Wu, Zhi Wang, Di Wang
Arbutin, a natural polyphenol isolated from the bearberry plant Arctostaphylos uvaursi, possesses whitening and anticancer properties. The effects of arbutin on melanogenesis and its pro-apoptotic effect on B16 murine melanoma cells have not yet been reported. In the present study, acetylated arbutin was prepared in order to improve the biological effects of arbutin, and it was found to significantly inhibit the biosynthesis of melanin and tyrosinase activity compared with parent arbutin in B16 murine melanoma cells...
November 16, 2017: International Journal of Molecular Medicine
Chandra Kant Sharma, Monika Sharma, Kanika Prasad
Vitiligo is a condition of the skin distinguished by hypo-pigmentation. Etiology of this disorder is unknown, and several theories and mechanisms have been hypothesized. The inflammatory response in vitiligo is thought to be mediated by polymorphism in genes such as FOXP3, ACE, APE, GSTP1, TLR, SOD, CTLA-4, TAP/LMP gene cluster, etc. Theories including reactive oxygen species model, Nrf2-antioxidant response element (ARE) pathway, WNT pathway, tyrosinase activity, biochemical, molecular, and cellular alterations have been hypothesized to explain vitiligo pathogenesis...
2017: Critical Reviews in Eukaryotic Gene Expression
Elena Vetchinkina, Vladimir Gorshkov, Marina Ageeva, Yuri Gogolev, Valentina E Nikitina
We show here, to our knowledge for the first time, that the brown mycelial mat of the xylotrophic shiitake medicinal mushroom, Lentinus edodes, not only performs a protective function owing to significant changes in the ultrastructure (thickening of the cell wall, increased density, and pigmentation of the fungal hyphae) but also is a metabolically active stage in the development of the mushroom. The cells of this morphological structure exhibit repeated activation of expression of the genes lcc4, tir, exp1, chi, and exg1, coding for laccase, tyrosinase, a specific transcription factor, chitinase, and glucanase, which are required for fungal growth and morphogenesis...
2017: International Journal of Medicinal Mushrooms
Gokhan Zengin, Hassan H Abdallah, Ahmet Dogan, Adriano Mollica, Zaahira Aumeeruddy-Elalfi, Mohamad Fawzi Mahomoodally
The potentiality of bioactive phenolic compounds may result in plant extracts having multiple biological activities. The aim of this study was to investigate into the biological activities of the methanolic, ethyl acetate, and water extracts of Tchihatchewia isatidea Boiss, an endemic medicinal plant of Turkey. The phenolic compositions of the extracts were confirmed using RP-HPLC. Extracts were screened for their potential antioxidant through a panoply of assays; their anti-diabetic potential, and plausible inhibitory activity against tyrosinase and acetylcholinesterase...
November 30, 2017: Food and Chemical Toxicology
Huihui Li, Wei Liu, Fengyuan Zhang, Xinyue Zhu, Liqiu Huang, Haixia Zhang
The detection of tyrosinase, a biomarker for melanoma, is of great significance. Herein, a fluorescent tyrosinase probe, with resorufin as the fluorophore and m-tolylboronic acid pinacol ester as the receptor, is proposed. The response relies on tyrosinase-catalyzed hydroxylation of phenylboronic acid pinacol ester at adjacent position followed by 1,6-rearrangement-elimination to release resorufin. This probe well quantifies tyrosinase in the range from 1 to 100 U mL-1 with detection limit of 0.5 U mL-1. Importantly, the probe exhibits high selectivity for tyrosinase over other biological substances including reactive oxygen species...
December 4, 2017: Analytical Chemistry
Nan Zou, Yue Wei, Fenghua Li, Yang Yang, Xuemei Cheng, Changhong Wang
BACKGROUND: Compound Muniziqi granule (MNZQ) is a multi-component herbal preparation and a popular traditional Uighur medicine used in China for treating endocrine disorder-induced acne, chloasma, dysmenorrhea, menopausal syndrome, and melanoma. Harmine presented in MNZQ has been confirmed potential anticancer effect on the B16 cells among others. The purpose of this study is to explore the inhibitory effects of MNZQ against B16 cells and mechanism of autophagy and apoptosis induced by harmine in B16 cells...
December 2, 2017: BMC Complementary and Alternative Medicine
Carol López de Dicastillo, Fernanda Bustos, Ximena Valenzuela, Gracia López-Carballo, Jose M Vilariño, Maria Jose Galotto
The knowledge of the biological properties of fruits and leaves of murta (Ugni molinae Turcz.) has been owned by native Chilean culture. The present study investigated the phenolic content, the antioxidant, antimicrobial and anti-tyrosinase activities of different murta fruit and leaves extracts to approach their uses on future food, pharmaceutical and cosmetic applications. Extractions of murta fruit and leaves were carried out under water, ethanol and ethanol 50%. Phenolic content of these extracts was measured through Folin Ciocalteu test and the antioxidant power by four different antioxidant systems (ORAC, FRAP, DPPH and TEAC assays) owing to elucidate the main mechanism of antioxidant...
December 2017: Food Research International
Kyu-Seok Hwang, Jung Yoon Yang, Jooyun Lee, Yu-Ri Lee, Seong Soon Kim, Geum Ran Kim, Jin Sil Chae, Jin Hee Ahn, Dae-Seop Shin, Tae-Young Choi, Myung Ae Bae
BACKGROUND: The demand for anti-melanogenic agents is increasing due to the unwanted side effects of current treatments. To find an effective anti-melanogenic agent, we used zebrafish as a whole animal model for phenotype-based drug and cosmetic discovery screening. OBJECTIVES: The aim of this study was to identify and explore a small molecule that could be used for skin-whitening cosmetics. METHODS: Using zebrafish embryos, we examined the effects of 1000 compounds on zebrafish development and pigmentation...
November 20, 2017: Journal of Dermatological Science
Xiao Hu, Mei-Hua Yu, Gui-Rui Yan, He-Yao Wang, Ai-Jun Hou, Chun Lei
A new isoprenylated sanggenon-type flavanone, nigrasin K (1), together with three known analogs (2-4) and five known Diels-Alder adducts (5-9), were isolated from the twigs of Morus nigra. Their structures were elucidated by spectroscopic methods. Sanggenon M (2), chalcomoracin (5), sorocein H (6), kuwanon J (7), sanggenon C (8), and sanggenon O (9) showed significant inhibitory effects on mushroom tyrosinase.
November 30, 2017: Journal of Asian Natural Products Research
Fei Qu, Wei Huang, Jinmao You
In this work, we report a fluorescence strategy for detecting dopamine (DA) and sensing tyrosinase (TYR) activity on the basis of the dual-emission carbon dots (DECDs), which contain two emitters: the blue emitters (BE, maximum emission at 385nm) and yellow emitters (YE, maximum emission at 530nm). Gold nanoparticles (AuNPs) can effectively quench the two emissions of DECDs. The addition of DA aggregates AuNPs effectively, leading to the fluorescence recovery of dual emitters gradually. This strategy exhibits a high selectivity toward DA and shows good linear ranges, such as 0...
November 23, 2017: Colloids and Surfaces. B, Biointerfaces
Mario Vaccaro, Natasha Irrera, Giuseppina Cutroneo, Giuseppina Rizzo, Federico Vaccaro, Giuseppe P Anastasi, Francesco Borgia, Serafinella P Cannavò, Domenica Altavilla, Francesco Squadrito
Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis is still not well understood. Exposure to UVA and UVB induces nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, increasing tyrosinase activity and melanin synthesis, whereas inducible nitric oxide synthase over expression might be involved in hypopigmentary disorders. The aim of this study was to evaluate whether inducible nitric oxide synthase and neuronal nitric oxide synthase expression were modified in vitiligo skin compared to healthy controls...
November 26, 2017: International Journal of Molecular Sciences
Li Yin, Chao Niu, Li-Xin Liao, Jun Dou, Maidina Habasi, Haji Akber Aisa
Plants or plant-derived products have been routinely used in several traditional medicine systems for vitiligo treatment. It is well-known that melanogenesis can be promoted by certain flavonoid compounds isolated from the traditional Uyghur medicinal plant, Kaliziri. Therefore, Chalcones, one class of flavonoid compounds, has become an interesting target for the development of anti-vitiligo agents. A series of novel isoxazole chalcone derivatives have been designed, synthesized, and evaluated for biological activities by our group...
November 28, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Xue Yang, Shengke Li, Ziyi Wang, Simon Lee, Lian-Hui Wang, Ruibing Wang
The teratogenicity of a pesticide nereistoxin (NTX) and its derivative thiocyclam (THI) towards aquatic life was dramatically constrained by a synthetic nanoreceptor, cucurbit[7]uril, through selective encapsulation of the pesticides (KCB[7]-NTX of 3.24 (±0.31) × 106 M-1 and KCB[7]-THI of 7.46 (±0.10) × 105 M-1), as evidenced by the rate of hatchability, morphology development, and tyrosinase activity of zebrafish larvae incubated with the pesticides (3 ~ 300 µM) in the absence and in the presence of 300 µM cucurbit[7]uril, demonstrating a significant potential of the nanoreceptor in managing ecological pollution of these pesticides...
November 27, 2017: Chemistry, An Asian Journal
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