The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the ...The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).展开更多
A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and e...A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and eco-friendly. One potentially powerful dyestuff was obtained from (+)-catechin treated with tyrosinase after screening experiments using biobased materials. The obtained reddish orange colourant, 4-(3,4-dihydro-3α,5,7-trihydroxy-2H-1-benzopyran-2α-yl) 1,2-benzoquinone named “catechinone”, shows enough dyeability for decolourised white hair. Catechinone does not cause erythema or oedema on skin of rabbits. The colour is controlled by the addition of other biobased materials and a variety of colours of dyed hair are acquired. The fastness to light or washing for hair dyed by catechinone is high enough for practical use.展开更多
Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and ...Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and that produced by chemical reaction (CC) was studied changing the dyeing condition such as dye concentration, dyeing temperature, pH or the sort and concentration of salts. The colour of the hair dyed by EC or CC at 30°C is yellowish or reddish brown, respectively. The colour of the hair dyed by EC and CC is deeper at a higher dye concentration and at a higher temperature. Hair is dyed deepest by EC or CC at the solution pH = 6.04 or 5.45, respectively. The dyeability is increased by adding NaCl (≤4 M) or CaCl2 (≤1 M), while it is decreased by adding AlCl3. The colour fastness of the dyed hair to washing or ultraviolet light is high enough for practical use. Furthermore, it was found that colourants are obtained from tea extracts which contain catechin derivatives. Hair is dyed reddish brown by the colourants.展开更多
为了实现晒青毛茶儿茶素含量的快速检测,该研究利用高效液相色谱技术(High Performance Liquid Chromatography,HPLC)测定了50份晒青毛茶样品中的表没食子茶素没食子酸酯(Epigallocatechin Gallate,EGCG)、表没食子儿茶素(Epigallocatec...为了实现晒青毛茶儿茶素含量的快速检测,该研究利用高效液相色谱技术(High Performance Liquid Chromatography,HPLC)测定了50份晒青毛茶样品中的表没食子茶素没食子酸酯(Epigallocatechin Gallate,EGCG)、表没食子儿茶素(Epigallocatechin,EGC)、没食子酸(Gallic Acid,GA)三种儿茶素单体含量,结合样品的近红外光谱,分别建立了晒青毛茶三种儿茶素单体含量的偏最小二乘法(Partial Least Squares,PLS)模型,并对模型进行验证。实验结果表明,基于EGCG、EGC、GA含量所建立近红外模型的决定系数(Coefficient of Determination,R2)分别为99.99%、99.99%、99.92%;校正标准差(Root Mean Square Error of Calibration,RMSEC)分别为0.17、0.15、0.10;相对标准差(Relative Standard Deviation,RSD)分别为0.19%、0.27%、0.56%;外部验证的结果显示,三种儿茶素单体含量模型的预测值与真实值的平均绝对误差分别为0.13、0.12、0.07;平均相对误差分别为0.17、0.25、0.45。实验结果表明,该研究建立的近红外分析模型具有较高的预测准确度和稳定性,在快速检测晒青毛茶儿茶素方面具有潜在应用价值。展开更多
文摘The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).
文摘A novel colourant for hair dyeing was prepared by an enzymatic reaction with (+)-catechin and its characteristics as a hair dyestuff were studied. The study is aimed at inventing the hair dyestuff that is human- and eco-friendly. One potentially powerful dyestuff was obtained from (+)-catechin treated with tyrosinase after screening experiments using biobased materials. The obtained reddish orange colourant, 4-(3,4-dihydro-3α,5,7-trihydroxy-2H-1-benzopyran-2α-yl) 1,2-benzoquinone named “catechinone”, shows enough dyeability for decolourised white hair. Catechinone does not cause erythema or oedema on skin of rabbits. The colour is controlled by the addition of other biobased materials and a variety of colours of dyed hair are acquired. The fastness to light or washing for hair dyed by catechinone is high enough for practical use.
文摘Hair colouring was carried out by using catechinone prepared from (+)-catechin by enzymatic or chemical oxidation reaction. The difference of dyeability between the catechinone produced by enzymatic reaction (EC) and that produced by chemical reaction (CC) was studied changing the dyeing condition such as dye concentration, dyeing temperature, pH or the sort and concentration of salts. The colour of the hair dyed by EC or CC at 30°C is yellowish or reddish brown, respectively. The colour of the hair dyed by EC and CC is deeper at a higher dye concentration and at a higher temperature. Hair is dyed deepest by EC or CC at the solution pH = 6.04 or 5.45, respectively. The dyeability is increased by adding NaCl (≤4 M) or CaCl2 (≤1 M), while it is decreased by adding AlCl3. The colour fastness of the dyed hair to washing or ultraviolet light is high enough for practical use. Furthermore, it was found that colourants are obtained from tea extracts which contain catechin derivatives. Hair is dyed reddish brown by the colourants.
文摘为了实现晒青毛茶儿茶素含量的快速检测,该研究利用高效液相色谱技术(High Performance Liquid Chromatography,HPLC)测定了50份晒青毛茶样品中的表没食子茶素没食子酸酯(Epigallocatechin Gallate,EGCG)、表没食子儿茶素(Epigallocatechin,EGC)、没食子酸(Gallic Acid,GA)三种儿茶素单体含量,结合样品的近红外光谱,分别建立了晒青毛茶三种儿茶素单体含量的偏最小二乘法(Partial Least Squares,PLS)模型,并对模型进行验证。实验结果表明,基于EGCG、EGC、GA含量所建立近红外模型的决定系数(Coefficient of Determination,R2)分别为99.99%、99.99%、99.92%;校正标准差(Root Mean Square Error of Calibration,RMSEC)分别为0.17、0.15、0.10;相对标准差(Relative Standard Deviation,RSD)分别为0.19%、0.27%、0.56%;外部验证的结果显示,三种儿茶素单体含量模型的预测值与真实值的平均绝对误差分别为0.13、0.12、0.07;平均相对误差分别为0.17、0.25、0.45。实验结果表明,该研究建立的近红外分析模型具有较高的预测准确度和稳定性,在快速检测晒青毛茶儿茶素方面具有潜在应用价值。
