151 Repairing Bleach-Damaged Hair
Table I
Effects of the Treatment with Chicoric Acid and Copper (II) Chlorophyllin on the Amino Acid Compositions
of the Keratin Protein and the Bleached Haira
Keratin
Protein
Chicoric acid treated
keratin protein (The
rate of change by the
treatment)
Bleached
hair
Chicoric acid treated
bleached hair (The
rate of change by the
treatment)
Asp(Asn) 63.1 63.1 (1.0) 56.4 56.4 (1.0)
Glu(Gln) 113.6 113.9 (1.0) 106.2 111.1 (1.0)
Ser 83.8 82.0 (1.0) 91.9 94.5 (1.0)
Gly 62.8 58.6 (0.9) 50.1 49.5 (1.0)
Thr 53.7 54.2 (1.0) 62.0 66.1 (1.1)
Arg 64.2 62.1 (1.0) 57.7 58.6 (1.0)
Ala 48.6 48.3 (1.0) 38.6 40.3 (1.0)
Tyr 20.0 18.2 (0.9) 17.7 18.0 (1.0)
Val 43.4 46.1 (1.1) 39.6 40.6 (1.0)
Met 3.3 3.0 (0.9) 4.3 4.3 (1.0)
Phe 22.7 22.8 (1.0) 15.4 14.0 (0.9)
Ile 29.6 30.4 (1.0) 21.8 22.9 (1.1)
Leu 73.1 73.7 (1.0) 49.0 46.8 (1.0)
Pro 68.7 62.7 (0.9) 69.3 61.2 (0.9)
His 4.0 2.0 (0.5) 7.8 5.1 (0.7)
Lys 20.6 11.9 (0.6) 23.3 13.7 (0.6)
Cys b 224.6 152.2 (0.7) 288.9 180.7 (0.6)
Total 1000 1000 1000 1000
(a) The keratin protein was treated with chicoric acid (3.6 mM) in the presence of the copper salt (4 ppm).
The bleached hair fibers were treated with chicoric acid (8.4 mM) in the presence of the copper salt
(4 ppm). Total amino acid content was assumed to 1000 residues. Tryptophan was not observed.
(b) A combined total of the cysteine and half-cysteine contents. The sum was not significantly altered
between different runs of the treatment. By contrast, the individual contents for the amino acid residues
were substantially varied, presumably owing to a complex redox action of the polyphenol-quinone
system in the present treatment.20,21
Figure 5. The UV-spectroscopic quantitative assay of the cysteine residue of the keratin protein which
treated under various conditions. (A) No treatment (B) only chicoric acid (C) only copper (II) chlorophyllin
(D) chicoric acid and the copper salt. See the experimental section for the spectroscopic quantification of the
thiol group.

152 JOURNAL OF COSMETIC SCIENCE
By contrast, chicoric acid, and the copper salt treated bleached-hair became much less
fluorescent as displayed in Figure 6C. The weakened fluorescence by treatment with
chicoric acid may be attributed to the decreased binding sites in the hair toward FITC-I,
or the aforementioned three kinds of amino acid residues were decreased in content upon
binding with chicoric acid.
Based on the previously mentioned results, it is suggested that the lysine, histidine and cysteine
residues in the model proteins and the bleached hair underwent a cross-linking reaction by
the action of the polyphenols in the presence of the catalytic concentration of the copper salt.
The reaction may be similar to that of the metal ion-catalyzed hardening of gelatin with
polyphenols.12 The tentative reaction pathways are displayed schematically in Figure 7A.
MICROSCOPIC OBSERVATIONS OF THE POLYPHENOL TREATED BLEACHED HAIRS
We also examined the swelling degree and the scale lifting of various hair fibers using the
optical microscope. The specimens were: the natural hair (I), the bleached hair (II), the
bleached hair treated with the copper salt (III), the bleached hair treated with chicoric acid
(IV), and the bleached hair fibers treated with chicoric acid in the presence of the copper
salt (V). The swelling degree of specimens I–V was measured upon warming in aqueous
5 M urea at 60°C for 1 hour to give the following results: I: 31 ± 5% II: 45 ± 6% III:
61 ± 10% IV: 44 ± 3% V: 26 ± 3%. It is worth noting that specimen V, which was
treated with chicoric acid and the copper salt, was not swollen as much as I (natural hair),
and its swelling degree was the lowest of that of the other specimens.
It was also observed that specimens II–IV underwent substantial scale lifting upon warming
in 5 M urea. See the representative photomicrograph of Figure 8A versus 8B, 8C and 8D
note the native hair (I) resisted even a medium lifting of the scales. The treatments of the
swollen bleached hair with the copper salt alone (III) and with the polyphenol alone (IV)
were not appreciably affect the scale lifting. By contrast, the scale lifting of the bleached
hair was markedly subdued by treating with the polyphenols in the presence of the copper
salt see Panel E. The swelling degree and the scale lifting were reproducibly observed by
employing 7 strands and 50 strands of each specimen, respectively. Therefore, the bleached
hair was considerably repaired with respect to the swelling degree and the scale lifting
when treating with a system of chicoric acid and the copper salt.
Specimen (V), which was obtained using chicoric acid and the copper salt, was visually
characterized with light brown color. The other specimens (II–IV) were all colored in tint
Figure 6. Fluorescence micrographs of the cross-section of various hair fibers which were stained with
FITC-I. (A) Untreated natural hair (B) bleached hair (C) bleached hair treated with chicoric acid (12 mM) in
the presence of cooper (II) chlorophyllin (4 ppm). See the experimental section for further details.