美白剂活性的生物化学检测方法

本用比色法测定美白剂对酷氨酸酶抑制作用，该法简单快速，并且对不同美白剂样品进行比较。     

天然美白成分在美白化妆品中的应用研究

采用测定酪氨酸酶活力、超氧阴离子自由基清除、对羟自由基的清除能力以及黑色素生成抑制能力的方法对28种中草药提取液的美白效果进行评价,同时研究提取剂组分、液料质量比、物料粒度对中草药提取物产率及其对酪氨酸酶抑制率的影响。结果表明,由甘草、人参、黄芪、芙蓉花、白芍等中草药组成的美白组合物1和由芙蓉花、桑白皮、葡萄籽、牡丹花、川芎、甘草组成的美白组合物3具有最佳的美白效果,具有最高的酪氨酸酶抑制率。     

美白添加剂美白效果的评价研究

本研究了皮肤美白效果的研究模型及美白添加剂的效果研究，结果表明，Ａｐｍｇ，甘草（小于０．１０％）对皮肤的黑色素的合成具有抑制作用，色素细胞的淡色化程度，Ａｐｍｇ优于甘草；此研究模型的建立为今后美白产品的筛选打下基础。     

皮肤化学美白剂抑制酪氨酸酶活性的研究

采用化学评价法,即通过测定皮肤美白剂对酪氨酸酶的活性抑制率,对9类13种皮肤美白剂的活性进行了评价与比较,排出了抑制次序;穷乡僻壤 制了各美白剂浓度与其酪氨酸抑制率关系曲线;多数美白剂呈钟形曲线;得到了各美白剂的ICmax及IC50;探讨了酪氨酸酶抑制率与美白效果评价的关系。     

壳聚糖改性水杨酸的刺激性和美白功效研究

水杨酸作为酸性美白物质具有去角质和清理毛孔能力,但其渗透性、刺激性较强。利用天然碱性生物大分子多糖--壳聚糖,对水杨酸进行分子结构改造,改造后产生水杨酸新型衍生物——水杨酸-g-壳聚糖。这种衍生物既能减轻水杨酸的刺激性,又具有良好的水溶性,适宜配方化妆品,其美白功效也有所提高。最佳反应条件：n（壳聚糖）：n（水杨酸）=1：0．5,pH=8,于70℃反应1h,水杨酸接枝率为70％。斑贴实验表明,水杨酸-g-壳聚糖刺激性较水杨酸明显地降低;人体美白实验表明水杨酸-g-壳聚糖与水杨酸有着相同的皮肤美白功效。     

植物活性美白成分的研究进展

综述了植物美白剂从单剂到复方剂型的发展与作用效果的研究进展,发现采用中医组方思想搭配的复方植物美白剂,从多维度、多靶点解决肌肤美白问题,安全又温和,将成为未来美白剂的一大热点研究.同时,论述了从植物中获取美白活性成分方式的影响与作用,得出发酵方式优于水、乙醇或其结合的提取方式.     

皮肤的美白

综述了皮肤黑色素生成的生理生化过程,色素沉着的机理以及近年来对黑素细胞调控方面的研究进展,同时介绍了评价美白剂效果的方法和一些新型的美白剂,并提出了这一领域未来的研究方向。     

天然活性物美白功效的细胞生物学研究

研究天然活性物对B16黑色素细胞的增值、细胞内氨酸酶活性及黑色素形成的影响，结果表明，各活性物能不同程度地抑制细胞增殖；除入参皂苷Rb外，各活性物能降低细胞内酷氨酸酶活性，茶多酚、金银花提取物和葡萄籽提取物较其他活性物能明显减少细胞黑色素的含量，是较为理想的化妆品美白添加剂，此研究模型能快速简便地筛选美白剂。     

皮肤美白活性物质研究现状及展望

黑素是影响人类皮肤颜色的主要因素。黑素形成过程中的影响因子与反应条件十分复杂。为了抑制黑素的形成，根据机理的不同，可以有多条途径。现在市售的美白化妆品多以抑制酪氨酸酶为主，但存在多种不足。对多种酶的抑制以及对内皮素、α-促黑素细胞激素等的抑制及平衡将是未来美白化妆品的新方向。     

美白、祛斑化妆品及其市场发展

叙述了黑色素形成机理，美白与祛斑途径，传统与新型美白剂组分，美白与祛斑化妆品的市场现状与发展。     

Preparation and characterization of superparamagnetic chitosan microspheres: Application as a support for the immobilization of tyrosinase

Superparamagnetic chitosan microspheres were prepared by a water‐in‐oil suspension‐crosslinking technique. To this end, magnetite particles were dispersed in a chitosan solution in acetic acid. The dispersion was added to toluene containing Span 20 as a surfactant with stirring. Chitosan solution droplets were hardened with glutaraldehyde. The magnetic chitosan microspheres obtained were characterized with scanning electron microscopy, differential thermal analysis, and vibrational magnetometry. The microspheres had a wide size distribution, ranging from 43 ± 25 to 255 ± 55 μm, that depended on the reaction conditions. The mean particle size decreased with an increase in the concentration of Span 20 or the amount of glutaraldehyde and with the addition of NaCl. However, a major size reduction was achieved by an increase in the stirring rate. Tyrosinase was immobilized on the microspheres. The immobilized enzyme retained 70% of its activity, as determined by the capacity to degrade phenolic compounds. The immobilized tyrosinase resulted in greater stability than the free enzyme. In addition, the enzyme maintained 65% of its phenol oxidation activity after 10 cycles of reuse. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 651–657, 2005     

茶皂素的纯化及抑制酪氨酸酶活性的研究

研究了茶皂素的纯化及纯化产物体外对马铃薯酪氨酸酶催化L-DOPA合成多巴醌的抑制作用及其机理。结果表明质量浓度为100 g/L时,市售茶皂素、经大孔树脂纯化的茶皂素TS及2种层析分离得到的茶皂素TS1和TS2对酪氨酸酶的抑制率分别为51.29%,90.06%,94.13%和82.47%;TS和TS1对酪氨酸酶IC50分别为48和40 g/L,抑制作用表现为可逆竞争性抑制,对酪氨酸酶的抑制常数分别为137和101 g/L。     

硫脲在酪氨酸酶催化中的抑制动力学

研究了硫脲对蘑菇酪氨酸酶活力的抑制效应。实验结果表明,硫脲与酪氨酸酶催化氧化产物醌反应,形成了无色的L-DOPA衍生物,从而阻断了多巴色素的形成。硫脲导致酪氨酸酶活力下降50%时的浓度(IC50)为1.37 mmol·L-1,在降低酶活的同时,硫脲能明显延长该酶的延滞时间,表现为不可逆反竞争性抑制。     

十一碳烯酰基苯丙氨酸的合成及其抑制酪氨酸酶二酚酶活性的研究

以十一烯酸和苯丙氨酸为原料,使用氯化亚砜将十一烯酸酰氯化,采用肖顿-鲍曼法(Schotten-Baumann)缩合反应合成了十一碳烯酰基苯丙氨酸钠,再经酸化分离后得到了十一碳烯酰基苯丙氨酸。利用IR,MS和~1H NMR对合成产物的结构进行了表征,同时考察了十一碳烯酰基苯丙氨酸对酪氨酸酶二酚酶活性抑制的机制。结果表明,十一碳烯酰基苯丙氨酸对酪氨酸酶二酚酶活性的抑制作用为竞争性可逆抑制,其半抑制浓度为3.711 g/L,抑制常数(K_i)为3.651 g/L。     

中药白芨提取物对酪氨酸酶的抑制作用

通过从水和乙醇中选取一种有效的提取剂,用回流法和超声波提取法提取中药白芨中的有效成分,分别以左旋多巴(L-DOPA)、邻苯二酚为底物,研究了白芨提取物对酪氨酸酶活性的影响。结果表明,白芨提取物对酪氨酸酶活性有抑制作用,66.7 mg/mL的超声波水提取物比醇提取物对酪氨酸酶有更为明显的抑制作用,其对酪氨酸酶的抑制率为62%,IC50值为28 mg/mL。     

乙胺硫脲抑制蘑菇酪氨酸酶活性动力学

研究了乙胺硫脲对蘑菇酪氨酸酶单酚酶和二酚酶活性的抑制效应.结果表明,乙胺硫脲对酪氨酸酶单酚酶和二酚酶活性均有抑制作用,导致单酚酶活力和二酚酶活力下降50%的乙胺硫脲浓度(IC50)分别为14.8和45.2μmol/L.在降低酪氨酸酶酶活的同时,乙胺硫脲能明显延长单酚酶和二酚酶的延滞时间.探讨了二酚酶延滞时间产生的原因:...     

Application of chitosan solutions gelled by melB tyrosinase to water‐resistant adhesives

An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenethylamine (dopamine). The tyrosinase‐catalyzed reaction with dopamine conferred water‐resistant adhesive properties to the semi‐dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase‐catalyzed quinone conversion and the subsequent nonenzymatic reactions of o‐quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel‐like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

香水莲花醇提取物对酪氨酸酶抑制作用的研究

以L-酪氨酸为底物,从马铃薯中提取酪氨酸酶,以熊果苷为阳性对照,采用比色法测定了香水莲花醇提取物对酪氨酸酶的抑制率。结果：香水莲花花托醇提取物、雄蕊醇提取物及总醇提取物的半数抑制浓度分别为0．12mg／mL、0．13mg／mL和0．48mg／mL,而阳性对照品熊果苷的半数抑制浓度为0．42mg／mL。表明,香水莲花花托醇、雄蕊醇提取物具有良好的抑制酪氨酸酶的作用,其效果优于熊果苷。香水莲花总醇提取物对酪氨酸酶的抑制作用与熊果苷相当。     

姜黄素多酚类似物对酪氨酸酶抑制活性的研究

酪氨酸酶抑制剂广泛应用于皮肤美白化妆品中.通过芳香醛分别与丙酮和环戊酮在酸性条件下催化缩合,合成了两个系列共10个姜黄素多酚类似物(A1-5和B1-5),并研究了其对酪氨酸酶的抑制活性.结果表明,含邻二酚羟基的姜黄素多酚类似物(A4和B4)对酪氰酸酶具有很强的抑制作用,半抑制浓度(IC50)分别为1.19,1.24 μmol/L,比曲酸(IC50为28.59μmoL/L)的活性强20多倍.抑制动力学研究表明,该类姜黄素多酚类似物对酪氨酸酶的抑制属于非竞争性抑制类型.     

Effect of water‐miscible solvents on the organic solvent‐resistant tyrosinase from Streptomyces sp. REN‐21

The effect of various water‐miscible organic solvents (ethanol, methanol, acetone, acetonitrile, N,N‐dimethylformamide (DMF) and dimethylsulfoxide (DMSO)) on the kinetics of 4‐tert‐butylcatechol (tBC) oxidation in the presence of different samples of organic solvent‐resistant tyrosinase (OSRT) has been studied. In contrast to mushroom tyrosinase the enzyme shows a high relative stability in solutions of organic solvents and increased activity toward the bulky and hydrophobic substrate, tBC, in respect to catechol. Rates of the studied OSRT‐catalyzed reactions are however reduced by the presence of organic solvents and for all studied samples of OSRT decrease exponentially with the content of an organic solvent. The effect has been satisfactorily described by the effect of organic solvents on the thermodynamic activity of tBC. The correlation of the inhibition parameters with the hydrophobicity of a particular solvent (log P), its intrinsic molar volume, V_i, and the Dimroth–Reichardt parameter, E_T(30), are shown. The results allow also the prediction of OSRT activity in aqueous solutions of water‐miscible organic solvents. Copyright © 2003 Society of Chemical Industry