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 CaCl 2 (≤1 M), while it is decreased by adding AlCl 3. 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.
The authors have studied hair dyeing by using biobased materials (obtained from natural materials) to invent novel hair dyeing techniques, which are milder and safer for a human body and eco-friendly, in order to reduce the risks accompanying hair dyeing. This is because sensitisation symptoms, dermatitides and systemic symptoms are caused for some people by the use of the oxidation hair dyes [
The catechinone is also produced by chemical reaction [
In the paper, the relationships between dyeing conditions such as the dye concentration of catechinone, dyeing temperature, pH or the sort and concentration of salts added and the dyeability for hair were studied comparing the enzymatically-produced catechinone (EC) with the chemically-produced one (CC). Then, the colour fastness to washing and ultraviolet (UV) light for the hair dyed by catechinone (EC and CC) was investigated. Furthermore, the authors tried to prepare hair dyestuffs from tea extracts, which contain (+)-catechin and catechin derivatives, by the chemical oxidation method, and their dyeability to hair was examined.
(+)-Catechin hydrate (Mw = 290.27, Sigma) and Polyphenon® 70S (Mitsui Norin) were used without further purification. Sunphenon® EGCg, BG-3 and 90S were kindly provided from Taiyo Kagaku and the powders were used as such. The Polyphenon and Sunphenons are the extracts of green tea leaf (Camellia sinensis) obtained in India and Kenya and in China, respectively. They contain catechins of high concentration as shown in
Product name | Polyphenon | Sunphenon | ||
---|---|---|---|---|
70S | EGCg | BG-3 | 90S | |
Lot No. | 1008271 | 207051 | 210041 | 207311 |
Catechins content(a)/wt% | ||||
(+)-Catechin | 2.2 | 0.1 | 2.7 | 1.4 |
(−)-Epicatechin | 7.5 | 0.6 | 7.9 | 4.5 |
(−)-Gallocatechin | 6.6 | - | 4.6 | 2.3 |
(−)-Epigallocatechin | 18.2 | - | 16.2 | 3.8 |
(−)-Catechin gallate | 0.7 | - | - | 0.8 |
(−)-Epicatechin gallate | 8.9 | 3.9 | 7.4 | 11.9 |
(−)-Gallocatechin gallate | 4.1 | 0.3 | 2.7 | 7.5 |
(−)-Epigallocatechin gallate | 32.0 | 92.1 | 51.2 | 46.8 |
Total catechin content(a) | 80.2 | 96.8 | 92.6 | 78.9 |
Total polyphenol content(b) | /(c) | ≈100 | 90.8 | 92.0 |
light-scattering measurements and 1.20 × 105 by electrophoresis, Sigma) was used as received. Monoethanol amine (MEA, Mw = 61.08, Nacalai tesque), disodium hydrogen phosphate (Na2HPO4, Fw = 141.96, Nacalai) and sodium dihydrogen phosphate (NaH2PO4, Fw = 119.98, Nacalai) as pH regulators were used without further purification. Water was used after distillation and ethanol (Mw = 46.07, 99.5%, Nacalai) was used without further purification.
The human hair samples (Mathai Japan, obtained from Asians and decolourised white, length: 11 cm) were bundled by a nylon band and kept under a low humidity. Citric acid (CA, Mw = 192.12, Nacalai), hydrochloric acid (HCl, 35.0 - 37.0 wt%, Mw = 36.46, Nacalai), sodium hydroxide (NaOH, Fw = 40.00, Nacalai), sodium chloride (NaCl, Fw = 58.44, Nacalai), calcium chloride (CaCl2, Fw = 110.98, Nacalai) and aluminium chloride hexahydrate (AlCl3∙6H2O, Fw = 241.43, Nacalai) were used without further purification. p-Aminophenol (PAP, Mw = 109.13, Katayama Chemical Industries) as an oxidation dye precursor, 5-amino-o-cresol (5AOC, Mw = 123.16, Tokyo Chemical Industry) as an oxidation dye coupler and ammonia solution (28 wt%, Nacalai) as a pH regulator were used without further purification. Hydrogen peroxide aqueous solution (H2O2, 30 wt%, Mw = 34.01, Santoku Chemical Industries) as an oxidising agent was diluted 5 times with distilled water. Kao Blaune Hair Manicure D13 (colour name: tea brown) was used as a commercially available acid dye, which contains orange II (C.I. 15510, C.I. Acid Orange 7), naphtol blue black (C.I. 20470, C.I. Acid Black 1), acid red (C.I. 45100, C.I. Acid Red 52) and fast acid magenta (C.I. 17200, C.I. Acid Red 33). NLES-227 (Taiko Oil Chemicals) that contains 27 wt% of sodium dodecyloxypolyoxyethylene (n = 2) sulphate (C12H25O (CH2CH2O)2 SO3Na) was used as anionic detergent for washing hair.
The dyestuff preparation was started by adding 5 ml of tyrosinase (32 kU) phosphate buffer aqueous solution (0.1 M NaH2PO4/Na2HPO4, pH = 7.0) into 495 ml of (+)-catechin (2.4 mmol) aqueous solution, which was saturated with oxygen by introducing O2 gas (≥ 99.5 vol%) for over 20 min at 30˚C. The concentration of (+)-ca- techin in the aqueous reaction solution was 4.8 mM. The reaction was performed under O2 atmosphere at 30˚C, and 200 ml of ethanol was finally added into the reaction solution to stop the reaction. The reaction solution was filtered and the filtrate was evaporated at 50˚C under below 50 hPa to obtain the powder of catechinone dye. The enzymatically-produced catechinone is abbreviated again here as EC.
The 100 g of (+)-catechin (0.17 mol∙kg−1) solution was prepared by using MEA (0.10 mol∙kg−1) water/ethanol mixed solution. The ethanol mass fraction (wE) and the molar fraction (xE) in the mixed solution were 0.50 and 0.28, respectively. The reaction was set off by introducing O2 gas into the (+)-catechin solution at 100 ml min−1 of flow rate at 30˚C. The solution was finally concentrated and then the resulting solid was ground to get catechinone dye powder. The chemically-produced catechinone is also abbreviated as CC.
The colourant preparation from four kinds of tea extracts was carried out by the chemical oxidation method. Polyphenon 70S, Sunphenon EGCg, BG-3 or 90S was dissolved in MEA (0.50 mol∙kg−1) water/ethanol solution (wE = 0.45, xE = 0.25). O2 gas was introduced to 100 g of 5.0 wt% tea extract solution at 30˚C, and then the solution was finally evaporated to obtain powder.
The bleached white hair (0.5 g or 1.0 g) was immersed into the dye solution (50 ml or 100 ml) containing fixed amount of the colourant from (+)-catechin (EC, CC) or tea extract without or with salt (NaCl, CaCl2 or AlCl3), and the solutions were shaken at 100 rpm of shaking speed for 40 min at 30˚C, 40˚C, 50˚C, 60˚C or 70˚C. The pH of the dyeing solution of EC or CC was adjusted by the addition of HCl and NaOH or citric acid, respectively. The dyed hair was washed with 0.27 - 0.81 wt% sodium dodecyloxypolyoxyethylene (n = 2) sulphate aqueous solution prepared from NLES-227 and rinsed with distilled water repeatedly at 30˚C or 40˚C. The hair was air-dried at room temperature.
In the oxidation dyeing, PAP (1.4 mmol), 5AOC (1.4 mmol) and ammonia (59 mmol) aqueous solution (50 g) and H2O2 (88 mmol) aqueous solution (50 g) were mixed, and then 0.5 g of hair was immersed into the mixed solution and it was shaken at 100 rpm at 30˚C for 40 min. In the dyeing by acid dye, the viscous dye solution was applied to the bundled hair by using a comb and the hair was allowed to stand at room temperature for 20 min. The dyed hairs were washed with 300 ml of distilled water with shaking at 100 rpm and 30˚C for 20 min repeatedly and were air-dried.
The colour of hair was measured by a Konica Minolta CM-2600d spectrocolourimeter and the resulting colour was expressed in L*a*b* standard colourimetric system (CIE 1976). The colour measurements were made employing 10˚-view angle, CIE standard illuminant D65 and SCI mode. All the reflection light from the sample including the regular reflection are integrated under the SCI mode. The L* is the lightness index, and a* and b* are the chromaticity coordinates. The positive values of a* indicate red and the negative values of that indicate green, and the positive values of b* indicate yellow and the negative values indicate blue. The C* is the chroma calculated by C* = {(a*)2 + (b*)2}1/2. The measurements of the ultraviolet-visible (UV-Vis) absorption spectra for the dyestuff aqueous solution were made by a Hitachi U-3900H spectrophotometer at 25˚C. The degree of swelling of hair (q) is calculated by q = ms/md, where ms and md are the mass of the swollen and dried hair, respectively. The ms and md were measured by a Mettler Toledo HG53 halogen moisture analyser at 120˚C for 15 min.
The colour fastness was estimated by the colour difference, ∆E*, for the dyed hair between before and after repeatedly washed, or the colour difference for the hair between before and after under UV irradiation. The ∆E* is calculated by ∆E* = {(L*t − L*i)2 + (a*t − a*i)2 + (b*t − b*i)2}1/2 where L*t, a*t, b*t, L*i, a*i, b*i are L*, a*, b* of treated (washed or UV irradiated) and freshly-dyed hair, respectively. In the experiments for colour fastness to washing, the dyed hair was washed with 0.27 wt% sodium dodecyloxypolyoxyethylene (n = 2) sulphate aqueous solution at 30˚C for 20 min, rinsed twice with distilled water at 30˚C for 20 min and dried by a Yamato Scientific DN400 constant temperature oven at 45˚C for 1 h. The colour was measured by the spectrocolourimeter after every washing. The experiments for colour fastness to UV light for the dyed hair was made by using a Sen Lights HL100G high-pressure mercury lamp. The intensity of the light was 20.0 mW∙cm−2 at 254 nm, 11.0 mW∙cm−2 at 310 nm and 9.8 mW∙cm−2 at 365 nm. The irradiation was performed for 10 h under ambient humidity. The colour was measured in the same way at each irradiation time.
Catechinone is prepared by both of the enzymatic oxidation in aqueous solution and the chemical oxidation in water/ethanol solution. The amount of the formed dye by the chemical method is over 20 times higher than that by enzymatic method, for the higher concentration of (+)-catechin in the water/ethanol reaction solution. However, the yield of catechinone by enzymatic preparation is 1.4 times higher than that by chemical preparation. The UV-Vis absorption spectra of EC and CC aqueous solution are approximately same but parts of the spectrum, especially at short wavelength (UV region), are little different. Both of the dyestuffs consist of catechinone (4-(3,4-dihydro-3α,5,7-trihydroxy-2H-1-benzopy-ran-2α-yl) 1,2-benzoquinone) chiefly and contain by-products [
The hair samples differ a little in the dyeability depending on the production lot, because the samples are human hair and, strictly speaking, no two are ever the same. Two kinds of hair differing in the lot, of which dyeability was slightly different, were used for the experiments. One was hair sample used for EC and another was for CC. Therefore, attention was focused on the tendency of the change in values of colour depending upon dyeing condition for each sample dyed by EC or CC rather than the absolute values.
The measured colour data expressed in chromaticity coordinates and in chroma-lightness index as a function of the dye concentration (cD) are shown in
The heating effect on the dyeability of hair by catechinone was investigated in order to shorten the dyeing time. The colour of hair dyed by EC and CC at 30˚C - 70˚C for 40 min was measured.
The colour of hair dyed by 0.60 wt% and over of EC is about the same, and the same for 1.0 wt% and over of CC. Therefore, 0.6 wt% of EC and 1.0 wt% of CC were adopted in the temperature effect experiments taking into account also the little different dyeability of each hair sample as described above.
The results obtained by observation with the naked eye show that the colour of hair dyed by both of the EC and CC becomes deeper with an increase in the dyeing temperature. It was found that the dyeability for hair by using both of the EC and CC solution increases with increasing temperature, and the dyeing time required decreases.
The L* for the EC- and CC-dyed hair decreases with T. The a* slightly increases with T up to 50˚C and it decreases over 50˚C for EC-dyed hair. The changing behaviour of a* for CC-dyed hair is similar to that forEC-dyed one though the magnitude of the change at lower temperatures is larger than that at higher temperature. The b* for EC- and CC-dyed hair decreases monotonously with T. It can be said that dyeability for hair by both of the EC and CC solution increases with increasing temperature up to 70˚C.
The higher temperature is favourable for accelerating the dyestuff molecules diffusion in a diffusion medium (here this is hair) and depresses dye adsorption onto dye-sites and the fixation in general. However, the amount of catechinone dye molecules fixed on hair has not determined and dyeing process has not clarified. It can be said at least that the dyestuff molecules diffusion dominates the dyeability for the catechinone hair dyeing sys-
tem under the conditions. The obtained results, however, show the higher temperature is favourable for obtaining higher dyeability in a shorter time and for rapid dyeing from the practical point of view. A local heating technique, for example, may be required to realise the practical dyeing.
On the other hand, the variation of a* for the EC and CC system is not monotonously. The colour change of dye solution during dyeing hair at higher temperature was observed. This indicates an alteration of dye molecules caused by heating. Then it was examined whether the dyestuff is altered by heating.
The results obtained from CC are presented here and
The dye solution pH is thought to be important factor for hair dyeing. Because the degree of swelling of hair and electric charge of the hair protein vary according to the pH and this may affect the dyestuff penetration into/ diffusion in hair and dyestuff fixation. Moreover, the aggregation state of dye molecules in solution may also depend upon the pH. Then the effect of the pH of dyeing solution on the dyeability of hair dyed by catechinone was investigated. The solubility of CC in each the dyeing solution of which pH is different is lower than that of EC. Then the pH-effect experiments for CC were made at higher temperature (50˚C) than those for EC (30˚C). The results obtained by visual observation show the colour of the hair dyed by EC is yellowish and this is almost same at pH = 1.83 - 6.04. The colour of hair dyed at pH = 6.04 by EC is deepest, and the hair is poorly dyed at pH = 8.38. Meanwhile, CC dyes hair reddish brown at pH = 4.09 - 7.48, and the colour is deepest at pH = 5.45.
The L* may take minimum and the a* reach maximum between pH = 3 and pH = 6 for hair dyed by EC. Its b* decreases with an increase in pH. On the other hand, the results for CC system show that L* of the dyed hair
decreases with increasing pH from 2.32, takes minimum at pH = 5.45 and increases slightly from pH = 5.45 and over. Its a* decreases with increasing pH from 5.45 and b* decreases monotonously with an increase in pH.
Subsequently, the relationship between the solution pH and the degree of swelling of hair was studied in order to clarify the mechanism of the pH effect on the dyeing.
It is well known that salts play important role in dyeing of charged fibres such as wool [
the addition of sodium chloride, calcium chloride or aluminium chloride on the dyeing by CC at 70˚C and at pH = 6.7 - 7.5 was studied. The colour of the hair dyed with NaCl is deepest at cS = 1.0 M, and it is deepest for CaCl2 at cS = 0.050 M, while it becomes paler with an increase in cS for AlCl3 in naked-eye observation.
It is concluded that the addition of a small amount of NaCl or CaCl2 are most effective and practical to improve the dyeability in the dyeing conditions (temperature, pH and salt addition) by comparing
Colour fastness of hair dyed by catechinone to washing and UV light is important property for practical hair dyeing. The colour fastness of hair dyed by catechinone to washing was first examined comparing with that of hair dyed by other colourants. The colours of the hair dyed by EC, CC, an oxidation dye (PAP + 5AOC) or an acid dye are dark brownish orange, dark yellowish orange, dark reddish brown or dark reddish brown, respectively. The colour of hair dyed by each the method was not same because adjusting the colour of hair samples is not easy the important point is the comparison of the difference in the colour change.
However, the changing behaviours of ΔE* for [the EC and CC system] and [the oxidation and acid dyes sys-
tem] are different. The time change in L* of hair dyed by each the method under UV irradiation is shown in
The results indicate that the hair dyed by EC or CC has enough high colour fastness to UV light. In addition, the colour fastness to visible light for the hair dyed by catechinone is also enough high [
It is important for the practical production of hair dyestuffs to prepare them from a massive amount of low materials. It was found that colourants are also prepared by the chemical oxidation method from four commercial tea extracts, which contain (+)-catechin and other catechin derivatives. Then, hair dyeing by using the colourants obtained from tea extracts was next examined and the high dyeing temperature (70˚C) was adopted at first. The resulting colour of hair samples expressed in L*a*b* colourimetry, which are dyed by the obtained colourants from the tea extracts is summarised in
The hair dyeing by using organic compounds such as mulberry fruits, alizarin, curcumin and juglone was also tried [
Sample hair dyed with | undyed | CC | dyestuffs from Polyphenon 70S | dyestuffs from Sunphenon EGCg | dyestuffs from Sunphenon BG-3 | dyestuffs from Sunphenon 90S |
---|---|---|---|---|---|---|
L* | 70.8 | 33.3 | 49.2 | 53.4 | 42.7 | 55.7 |
a* | 4.47 | 14.5 | 10.7 | 4.54 | 8.77 | 4.01 |
b* | 25.8 | 19.3 | 22.7 | 18.8 | 20.0 | 19.3 |
C* | 26.2 | 24.1 | 25.1 | 19.3 | 21.9 | 19.7 |
Dyeing conditions: cD = 1.0 wt%, T = 70˚C and t = 40 min.
Catechinone is obtained from (+)-catechin by both the enzymatic and chemical oxidation method. Hair is dyed deeper red brown of the higher dye concentration, for longer dyeing time and at higher dyeing temperature. Hair is dyed darkest by EC at pH = 6.04 and by CC at pH = 5.45. A small amount of NaCl and CaCl2 addition into the dye solution increases the dyeability. The colour fastness to washing and UV light for the hair dyed by catechinone is high enough for practical use. Hair dyestuff is obtained from commercially available tea extracts.
This study was financially supported partly by the Japan Society for the Promotion of Science Research Foundation Grant (No. 21500732), Japan Science and Technology Agency as Adaptable & Seamless Technology Transfer Program through Target-driven R&D (No. AS2211611E) and Kyoto Institute of Technology Venture Laboratory in VL Research Project 2012 Category I (No. I-01).