keyword
MENU ▼
Read by QxMD icon Read
search

Tyrosinase

keyword
https://www.readbyqxmd.com/read/28522265/screening-for-bioactive-natural-products-from-a-67-compound-library-of-glycyrrhiza-inflata
#1
Yan Lin, Yi Kuang, Kai Li, Shuang Wang, Wei Song, Xue Qiao, Gulnar Sabir, Min Ye
Licorice shows a variety of pharmacological activities. This work aims to discover bioactive natural products from one botanical source of licorice, Glycyrrhiza inflata. A total of 67 free phenolics were isolated to form a compound library. Based on the bioactivities of licorice, these compounds were screened using cell- or enzyme-based bioassay methods. A total of 11 compounds exhibited potent cytotoxic activities against three human cancer cell lines (HepG2, SW480 and MCF7), while showed little toxicity on human normal cell lines LO2 and HEK293T...
May 6, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28515769/inhibitory-effects-of-different-fractions-of-nepeta-satureioides-on-melanin-synthesis-through-reducing-oxidative-stress
#2
Seyed Ahmad Emami, Rezvan Yazdian-Robati, Mohammad Sadeghi, Javad Baharara, Elaheh Amini, Farzaneh Salek, Zahra Tayarani-Najaran
Nepeta satureioides Boiss. has been used in traditional medicine of eastern countries and is famous for its medicinal properties. The aim of this study was to evaluate the effect of methanol (MeOH), n-hexane and dichloromethane (CH2Cl2) fractions of the extract on melanin synthesis and oxidative stress in B16F10 melanoma cell line. The B16F10 cell line viability after treatment with increasing concentrations of different fractions of the plant (5-60 μg/mL) was measured using MTT assay. The inhibitory effect on synthesis of melanin, mushroom tyrosinase activity, cellular tyrosinase and oxidative stress were determined by the colorimetric and fluorometric methods...
April 2017: Research in Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28510134/paramagnetics-melanin-and-mn-2-in-black-soldier-fly-hermetia-illucens
#3
N A Ushakova, A E Dontsov, A I Bastrakov, N Y Garmash, D S Pavlov
Larva, prepupa (last instar larva), pupa, and an empty shell of pupa after hatching of the black soldier fly Hermetia illucens contain eumelanin, an active synthesis of which is observed at the prepupal stage, which is probably due to the release of prepupa from the feed substrate thickness to the open space for pupation. It was shown for the first time that prepupa contains high quantities of the magnetically active form of manganese Mn(2+). This fact indicates that Mn(2+) stimulates the copper-containing tyrosinase-the key enzyme in the synthesis of melanin in the period of migration and adaptation of the insect to the solar radiation...
March 2017: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28509848/biosensor-based-on-tyrosinase-immobilized-on-graphene-decorated-gold-nanoparticle-chitosan-for-phenolic-detection-in-aqueous
#4
Fuzi Mohamed Fartas, Jaafar Abdullah, Nor Azah Yusof, Yusran Sulaiman, Mohd Izham Saiman
In this research work, electrochemical biosensor was fabricated based on immobilization of tyrosinase onto graphene-decorated gold nanoparticle/chitosan (Gr-Au-Chit/Tyr) nanocomposite-modified screen-printed carbon electrode (SPCE) for the detection of phenolic compounds. The nanocomposite film was constructed via solution casting method. The electrocatalytic activity of the proposed biosensor for phenol detection was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Experimental parameters such as pH buffer, enzyme concentration, ratio of Gr-Au-Chit, accumulation time and potential were optimized...
May 16, 2017: Sensors
https://www.readbyqxmd.com/read/28509370/use-of-mushroom-tyrosinase-to-introduce-michaelis-menten-enzyme-kinetics-to-biochemistry-students
#5
William H Flurkey, Jennifer K Inlow
An inexpensive enzyme kinetics laboratory exercise for undergraduate biochemistry students is described utilizing tyrosinase from white button mushrooms. The exercise can be completed in one or two three-hour lab sessions. The optimal amounts of enzyme, substrate (catechol), and inhibitor (kojic acid) are first determined, and then kinetic data is collected in the absence and presence of the inhibitor. A Microsoft Excel template is used to plot the data and to fit the Michaelis-Menten equation to the data to determine the kinetic parameters Vmax and Km ...
May 2017: Biochemistry and Molecular Biology Education
https://www.readbyqxmd.com/read/28508671/chemometric-profile-antioxidant-and-tyrosinase-inhibitory-activity-of-camel-s-foot-creeper-leaves-bauhinia-vahlii
#6
Pritipadma Panda, Priyanka Dash, Goutam Ghosh
The present study is the first effort to a comprehensive evaluation of antityrosinase activity and chemometric analysis of Bauhinia vahlii. The experimental results revealed that the methanol extract of Bauhinia vahlii (BVM) possesses higher polyphenolic compounds and total antioxidant activity than those reported elsewhere for other more conventionally and geographically different varieties. The BVM contain saturated fatty acids such as hexadecanoic acid (10.15%), octadecanoic acid (1.97%), oleic acid (0.61%) and cis-vaccenic acid (2...
May 16, 2017: Natural Product Research
https://www.readbyqxmd.com/read/28507486/melanin-and-lipofuscin-as-hallmarks-of-skin-aging
#7
REVIEW
Anna Skoczyńska, Elżbieta Budzisz, Ewa Trznadel-Grodzka, Helena Rotsztejn
Discoloration are symptoms of skin aging. They are connected with presence of melanin and lipofuscin, whose excess and abnormal distribution in the skin cause dark spots to appear. Melanin is formed under the influence of tyrosinase during melanogenesis. Its content changes with age, which may be a result of menopause. Lipofuscin is another example of the age pigment. It is composed of proteins, lipids and carbohydrates. It is described as an age pigment because its content increases with age. The formation and accumulation of lipofuscin is inevitable and leads to cell and homeostasis dysfunction because it reduces the proteasome activity...
April 2017: Postȩpy Dermatologii i Alergologii
https://www.readbyqxmd.com/read/28506040/codon-usage-patterns-of-tyrosinase-genes-in-clonorchis-sinensis
#8
Young-An Bae
Codon usage bias (CUB) is a unique property of genomes and has contributed to the better understanding of the molecular features and the evolution processes of particular gene. In this study, genetic indices associated with CUB, including relative synonymous codon usage and effective numbers of codons, as well as the nucleotide composition, were investigated in the Clonorchis sinensis tyrosinase genes and their platyhelminth orthologs, which play an important role in the eggshell formation. The relative synonymous codon usage patterns substantially differed among tyrosinase genes examined...
April 2017: Korean Journal of Parasitology
https://www.readbyqxmd.com/read/28505073/anti-pigmentary-effect-of-4-hydroxysattabacin-from-the-marine-derived-bacterium-bacillus-sp
#9
Kyuri Kim, Alain S Leutou, Haein Jeong, Dayoung Kim, Chi Nam Seong, Sang-Jip Nam, Kyung-Min Lim
Bioactivity-guided isolation of a crude extract from a culture broth of Bacillus sp. has led to the isolation of (-)-4-hydroxysattabacin (1). The inhibitory effect of (-)-4-hydroxysattabacin (1) was investigated on melanogenesis in the murine melanoma cell line, B16F10, and human melanoma cell line, MNT-1, as well as a pigmented 3D-human skin model. (-)-4-Hydroxysattabacin treatment decreased melanin contents in a dose-dependent manner in α-melanocyte stimulating hormone (α-MSH)-stimulated B16F10 cells. Quantitative real time PCR (qRT-PCR) demonstrated that treatment with (-)-4-hydroxysattabacin down-regulated several melanogenic genes, including tyrosinase, tyrosinase-related protein 1 (TRP-1), and tyrosinase-related protein 2 (TRP-2) while their enzymatic activities were unaffected...
May 13, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28501601/novel-inhibitors-of-tyrosinase-produced-by-the-4-substitution-of-tct-%C3%B0
#10
Jing Liu, Mengrong Li, Yanying Yu, Shuwen Cao
Novel Tyrosinase Inhibitors of 4-functionalized Thiophene-2-carbaldehyde thiosemicarbazone (TCT) derivatives (1-8) had been synthesized and Spectrofluorimetry, (1)H and (13)C NMR titration and Molecular docking had been used to investigate their inhibitory activities and mechanisms on tyrosinase. The results showed that the inter-molecular interactions or hydrogen bond formation by increasing length of carbon chain or introducing benzene ring to the 4-functionalized ester group promoted or stabilized formation of complexes between modifier and tyrosinase, and enhanced the inhibitory activity of modifiers...
May 10, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28501487/inhibition-on-cholinesterase-and-tyrosinase-by-alkaloids-and-phenolics-from-aristotelia-chilensis-leaves
#11
Carlos L Cespedes, Cristian Balbontin, Jose G Avila, Mariana Dominguez, Julio Alarcon, Cristian Paz, Viviana Burgos, Leandro Ortiz, Ignacio Peñaloza-Castro, David S Seigler, Isao Kubo
It is reported in this study the effect of isolates from leaves of Aristotelia chilensis as inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and tyrosinase enzymes. The aim of the paper was to evaluate the activity of A. chilensis towards different enzymes. In addition to pure compounds, extracts rich in alkaloids and phenolics were tested. The most active F5 inhibited AChE (79.5% and 89.8% at 10.0 and 20.0 μg/mL) and against BChE (89.5% and 97.8% at 10.0 and 20.0 μg/mL), showing a strong mixed-type inhibition against AChE and BChE...
May 10, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/28500345/heterologous-expression-and-characterization-of-functional-mushroom-tyrosinase-abppo4
#12
Matthias Pretzler, Aleksandar Bijelic, Annette Rompel
Tyrosinases are an ubiquitous group of copper containing metalloenzymes that hydroxylate and oxidize phenolic molecules. In an application context the term 'tyrosinase' usually refers to 'mushroom tyrosinase' consisting of a mixture of isoenzymes and containing a number of enzymatic side-activities. We describe a protocol for the efficient heterologous production of tyrosinase 4 from Agaricus bisporus in Escherichia coli. Applying this procedure a pure preparation of a single isoform of latent tyrosinase can be achieved at a yield of 140 mg per liter of autoinducing culture medium...
May 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28495084/structural-insight-into-the-active-site-of-mushroom-tyrosinase-using-phenylbenzoic-acid-derivatives
#13
Takahiro Oyama, Atsushi Yoshimori, Satoshi Takahashi, Tetsuya Yamamoto, Akira Sato, Takanori Kamiya, Hideaki Abe, Takehiko Abe, Sei-Ichi Tanuma
So far, many inhibitors of tyrosinase have been discovered for cosmetic and clinical agents. However, the molecular mechanisms underlying the inhibition in the active site of tyrosinase have not been well understood. To explore this problem, we examined here the inhibitory effects of 4'-hydroxylation and methoxylation of phenylbenzoic acid (PBA) isomers, which have a unique scaffold to inhibit mushroom tyrosinase. The inhibitory effect of 3-PBA, which has the most potent inhibitory activity among the isomers, was slightly decreased by 4'-hydroxylation and further decreased by 4'-methoxylation against mushroom tyrosinase...
April 26, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28493937/action-of-tyrosinase-on-alpha-and-beta-arbutin-a-kinetic-study
#14
Antonio Garcia-Jimenez, Jose Antonio Teruel-Puche, Jose Berna, José Neptuno Rodriguez-Lopez, Jose Tudela, Francisco Garcia-Canovas
The known derivatives from hydroquinone, α and β-arbutin, are used as depigmenting agents. In this work, we demonstrate that the oxy form of tyrosinase (oxytyrosinase) hydroxylates α and β-arbutin in ortho position of the phenolic hydroxyl group, giving rise to a complex formed by met-tyrosinase with the hydroxylated α or β-arbutin. This complex could evolve in two ways: by oxidizing the originated o-diphenol to o-quinone and deoxy-tyrosinase, or by delivering the o-diphenol and met-tyrosinase to the medium, which would produce the self-activation of the system...
2017: PloS One
https://www.readbyqxmd.com/read/28491137/boosting-lpmo-driven-lignocellulose-degradation-by-polyphenol-oxidase-activated-lignin-building-blocks
#15
Matthias Frommhagen, Sumanth Kumar Mutte, Adrie H Westphal, Martijn J Koetsier, Sandra W A Hinz, Jaap Visser, Jean-Paul Vincken, Dolf Weijers, Willem J H van Berkel, Harry Gruppen, Mirjam A Kabel
BACKGROUND: Many fungi boost the deconstruction of lignocellulosic plant biomass via oxidation using lytic polysaccharide monooxygenases (LPMOs). The application of LPMOs is expected to contribute to ecologically friendly conversion of biomass into fuels and chemicals. Moreover, applications of LPMO-modified cellulose-based products may be envisaged within the food or material industry. RESULTS: Here, we show an up to 75-fold improvement in LPMO-driven cellulose degradation using polyphenol oxidase-activated lignin building blocks...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28490129/tyrosinase-inhibitory-mechanism-of-betulinic-acid-from-dillenia-indica
#16
Rajarshi Biswas, Joydeb Chanda, Amit Kar, Pulok K Mukherjee
The fruit of Dillenia indica L. is extensively used as a food additive. Betulinic acid (BA) is the most prominent secondary metabolite present in D. indica. This study screened the bioassay guided isolation of BA from D. indica and explored its tyrosinase inhibitory mechanism. Half maximal inhibitory concentration (IC50) of BA were calculated as 13.93µM and 25.66µM for diphenolase and monophenolase. Enzyme kinetic analysis revealed that BA inhibited tyrosinase activity non-competitively. Further, conformational analysis of tyrosinase with BA was measured by fluorescence and circular dichroism spectroscopy...
October 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28490115/mechanistic-insights-into-tyrosinase-mediated-crosslinking-of-soy-glycinin-derived-peptides
#17
Sivan Isaschar-Ovdat, Ayelet Fishman
Tyrosinase from Bacillus megaterium (TyrBm) was previously used to modulate soy glycinin-based emulsions and gels. To study the crosslinking mechanism, TyrBm oxidation of three tyrosine-containing octapeptides derived from glycinin was analyzed by oxygen consumption measurements, absorbance and mass spectrometry. A significant lag period and lower activity were measured when tyrosine was located in the middle of the peptide chain. Mass spectrometry analysis showed that these peptides are crosslinked via the oxidative quinone ring of the tyrosine residue by aryl-alkylamine addition or aryloxy radical coupling to form di-DOPA (3,4-dihydroxyphenylalanine)...
October 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28488417/melanogenesis-inhibitory-and-antioxidant-activities-of-phenolics-from-periploca-forrestii
#18
Cai-Ling Sun, Lei Chen, Jian Xu, Wei Qu, Li Guan, Wen-Yuan Liu, Toshihiro Akihisa, Feng Feng, Jie Zhang
Two new tetrahydrofuran-type lignans, (-)-gentioluteol-9-O-β-D-glucoside (1), (-)-berchemol 9-O-β-D-apiofuranosyl-(1→6)-O-β-D-glucopyranoside (2), along with sixteen known compounds 3-18 were isolated from the 95% EtOH extract of the stems of Periploca forrestii. The structures of new tetrahydrofuran-type lignans were determined by HR-ESI-MS and various NMR techniques in combination with CD method. Then, their antioxidant abilities were evaluated by 1,1-diphenyl-2-picrylhydrazul (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and ferric-reducing antioxidant power (FRAP) assays...
May 10, 2017: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28488389/chemical-profiling-and-assessment-of-antineurodegenerative-and-antioxidant-properties-of-veronica-teucrium-l-and-veronica-jacquinii-baumg
#19
Jelena Č Živković, João C M Barreira, Katarina P Šavikin, Ana Z Alimpić, Dejan S Stojković, Maria Inês Dias, Celestino Santos-Buelga, Sonja N Duletić-Laušević, Isabel C F R Ferreira
Neuroprotective potential of V. teucrium and V. jacquinii methanol extracts was analyzed. Chemical analysis of investigated extracts showed the presence of phenolic acid derivatives, flavonoids and one secoiridoid. The detected flavonoids derived from flavones (luteolin and isoscutellarein in V. jacquinii; apigenin, isoscutellarein and luteolin in V. teucrium) and flavonol (quercetin in V. jacquinii). Acteoside was the dominant compound in V. jacquinii, while plantamajoside and isoscutellarein 7-O-(6'''-O-acetyl)-β-allosyl (1'''→2''')-β-glucoside were the major phenolics in V...
May 10, 2017: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28484254/crispr-cas9-mediated-mutation-of-tyrosinase-tyr-3-utr-induce-graying-in-rabbit
#20
Yuning Song, Yuxin Xu, Jichao Deng, Mao Chen, Yi Lu, Yong Wang, Haobin Yao, Lina Zhou, Zhiquan Liu, Liangxue Lai, Zhanjun Li
The 3' untranslated regions (UTRs), located at the end of mRNA molecules, are believed to play a role in RNA replication and/or protein translation. Mutations in the tyrosinase (Tyr) gene are known to cause recessive albinism in humans and other species. In this study, to test whether the CRISPR/Cas9 system works on the mutation of the UTRs regulatory region in rabbit, the 3' UTR of the rabbit Tyr gene was deleted by a dual sgRNA directed CRISPR/Cas9 system. As expected, gray coat color and reduced melanin in hair follicles and irises was found in the mutated rabbit, thus increasing confidence in the association of the mutation of the Tyr 3' UTR with graying in rabbit...
May 8, 2017: Scientific Reports
keyword
keyword
15364
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"