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E#ect of Suppressing Melanin Formation by Reductive
Hot Spring Water System (Sulfur Hot Springs)
Shoichi OKOUCHI+, Takao OHAMI+, Kuniyasu ASAI+, Hideyuki OHNAMI+,
Shigeo IKEDA+ and Yuko AGISHI,

Abstract
It has been generally said that sulfur hot spring water is e#ective in making the skinbeautiful. Through our previous investigation of sulfur hot spring water of Nozawa spa
in Nagano Prefecture, we revealed that habitual bathing in reductive water can improveor recover skin elasticity. In the present study, using samples of reductive sulfur springwater collected from Nozawa spa (sulfur spring water : pH-2.., total S-/+.0 ppm, H,S,., ppm) and from Takayu spa (acidic-sulfur-containing calcium-sulfate spring water : pH-,.-1, H,S-+.2.2 ppm) in Fukushima Prefecture, we have examined their e#ects of suppressing the formation of melanin that will cause blotches and freckles or pigmentarydeposits at sunburn, i.e., the e$cacy of reductive sulfur spring water in skin lightening.
Each water sample of Nozawa spa and Takayu spa was adjusted to pH 1, optimal for
enzymatic reactions, by using a phosphoric acid bu#er. To each water sample, tyrosine
and tyrosinase were added, and dopachrome known as an intermediate product in theprocess of melanin formation was checked by observing variations in absorbance at .1/
nm. In the experiments, no increase in absorbance was found with the lapse of time in thewater samples collected from both of Nozawa and Takayu spas, which signiﬁes that reductive sulfur spring water has an advantageous e#ect of suppressing melanin formation.
Furthermore, since melanin is formed in the skin, we have also carried out experiments to investigate cutaneous permeability of reductant components of the hot springwater samples. As a substitute for the skin, we used a nylon-polyethylene double-layered
ﬁlm having an equivalent-to-skin barrier function that does not allow permeation of water. The results conﬁrmed that the reductant components (H,S) of sulfur spring water
have an appreciable degree of cutaneous permeability. Hence, besides being applicable toimprovement or recovery of skin elasticity, reductive sulfur hot spring water can also+ +2.ῌ2/2.  -ῌ1ῌ, + Fuculty of Bio Science and Applied Chemistry, Hosei University, Kajinocho -ῌ1ῌ,, Koganei-shi, Tokyo +2.ῌ2/2., Japan.
,!"#$%&'() +*2ῌ**1/ *+*, .ῌ0ῌ2ῌ,-*, , Research Institute of Health Resort Medicine, Konan .ῌ0ῌ2ῌ,-*,, Minato-Ku, Tokyo +*2ῌ**1/, Japan.

2

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suppress melanin formation to provide skin-lightening e$cacy.
Key words : Melanin, dopachrome, reductive hot spring water, Nozawa spa, Takayu spa,
cutaneous permeability.

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 Q* R3# ST !U)U" #$4 O)V%-
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Fig. + Melanin formation mechanism.
 +    !"#$% &' ()*+,-*. /0/0*12345$ 6$)*7 89:2 ;<= >?@ABCD*EFGHIJ!KLMNOPQ R !"S!!K LMNO7"T#U*VWL
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et al., +33. ; ,**0 (f Fig. + %fg hi,-*Ej^_$7\]<abc^_%k R. LMNOPQ R !"l&(f%$:*7mhi,Jn'"(!!K o!.2))fhiopq=O
C rAstpO^ 7 %uu7*n'.* !v) *n'.Bpq=O C+,weQBpq=O C -x.**yR.*n'(zZ{O,/K|}0"~)f2#2 -6LMNOPQ RQ1mn'"/0!K+,-hi,Q1!.2_-G7
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Scheme of experimental arrangement for ﬁlm permeation of reductant components.
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789: ;678<=: 3>81
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0x98 Fig. + LS+0fghHO
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Fig. - ORP-pH relationships of hot spring water samples and their pH-adjusted samples (pH 1).
 : Water sample from Nozawa spa.  : Water
sample from Nozawa spa adjusted in pH 1.  :Water sample from Takayu spa.  : Water sample
from Takayu spa adjusted in pH 1.
 - 
 pH  pH 1  ORP-pH  :   :  pH 1
 :    :  pH 1

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 . 
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H

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    !"Chromatic change of aqueous solution with time in melanin formation reaction.
 / 


+,-./012345 6789:;<=>? @;A"BCDE# FGHI J K+,-./01238 B
 FL4?MN# 1OPQ RSTUVWJXYBZ;4[JM? D
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DE#
Fig. 0 Variation in absorbance (.1/ nm) with time of water samples from Nozawa and Takayu spas in melanin formation reaction.
 : Puriﬁed water (pH 1).  : Water sample from
Nozawa spa (pH 1).  : Water sample from Takayu
Spa (pH 1).
 0  
!.1/ nm" #$
 :  pH1:
 pH 1
 : 
 pH 1-%- &'()*+,-.

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GeOQ?nB nx w J pH B1qyT@4| ORP
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Fig. 1 Chromatic change with time of water samples from Nozawa and Takayu spas, andascorbic acid aqueous solution in melanin formation reaction.
 1 
   !"#$%&'()

Fig. 2 Variations in ORP-pH in ﬁlm permeation experiment on ascorbic acid aqueous solution.
 : Puriﬁed water in ﬁlm enclosure at time *.  :Variation with time in puriﬁed water in ﬁlm enclosure.  : Ascorbic acid aqueous solution.
 2  !"#$*+, -./ ORPpH () : 
  : 
 :  

8Fig. 3 Variations in ORP-pH in ﬁlm permeation experiment on water samples collected from Nozawa spa.
 : Puriﬁed water in ﬁlm enclosure at time *.  :Variations with time in puriﬁed water in ﬁlm enclosure.  : Water sample from Nozawa spa.
 3 *+, -./ ORP-pH () : 
  : 
 : 

9 /3 : #,**3$%&'#($ )*+,-. /0123;<+=>?@A;BC4
Fig. ++ )D Fig. 25Fig. +* EFGFHIJK ῌ L;MNOCPQ ORP #ORPeq$>R)STOC AI U #VWX +332$ >YZ[;\OC4
AI6#ORPeqORP$ 77777ῌ

]^_` ORP UD pH UaKbcd]+=>eX EfgKbc^h AI
UKhdiOC4 E AI U?VBhj
*k%&'K\O lmDPQ'Kn  ]+4  ! " #o$ D Y
Fig. +* Variations in ORP-pH in ﬁlm permeation experiment on water samples collected from Takayu spa.
 : Puriﬁed water in ﬁlm enclosure at time *.  :Variations with time in puriﬁed water in ﬁlm enclosure.  : Water sample from Takayu spa.
 +* 
 ORP-pH  : 
  : 
 : 

pOdq AI UDrslmtu;  !DKvwO^h=>K\Odh+#Fig. ++$4 xy (' #o$ z*{ #o$  ;D %&'|?KvwO AI U?Y>>q)}~O )!; |hy?  |vwDVBh3
K\OC4 OeO > Od|?e^kh;  #V
X ,**2$ ;\OC*) }23KOC? =FD?
!;<+=>eX HHS8H,S, *)u;  #,., ppm$ }
H,S ?/0F )*k |?vwOCq XF+4 OeO 
 |D¡q ]+=>eX ¢£)>¤d¥¦^ | YK§¨C ©@ ?ª >«_F+4
Fig. ++ Variations with time in AI in ﬁlm permeation
experiment.
 : Water sample from Takayu spa.  : Water
sample from Nozawa spa.  : Ascorbic acid aqueous solution.
 ++ AI 
 :   :   :  !
".   %&'(; ¬­z*{!'®
),-. /0123K ]+=>?@AFC4 X) ,-. D;/0
F+C¨ ¯ 20vw?° >^+=>eX EFX%&' 20 #H,S$?±­I²K ]+³´Kvw]+=>K@AOC4 =F)*k (µY¶h·
XFdBC¸¹23)ºhd  })»  ¸¼23q ½;B+?\FC49     

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

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 

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 

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

Q ! *+ klm /  +333 : 2- ORP opKLq  pH   .3 /3ῌ0..


Q *+ klm ,*** : 0op ORP  pH   /* 3.ῌ+*+.
Okouchi, S., Suzuki, M., Sugano, K., Kagamimori, S. and Ikeda, S. (,**,) : Water desirable forthe human body in terms of oxidation-reduction potential (ORP) to pH relationship, J.
Food Sci., 01, +/3.ῌ+/32.

 12  klm ,**- : KLM,SR  /- +ῌ3.
 12  3   4

,**, : 0op

x,-.567 , L8p,SR  /, +,ῌ+3.
 Aileem Tamura, (   s#"

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Ohnami, S., Koumura, K., Ikeda, S. and Okouchi, S. (,**-) : ORP (oxidation-reduction potential)
pH relationship between hot spring waters and human body ﬂuids, Proceedings of the-2th Conference of Societe Internationale des Techniques Hydrothermales (Beppu, Ohita,Japan), -,*ῌ-,/.

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Shirota, S., Miyazaki, K., Aiyama, R., Ichioka, M. and Yokokura, T. (+33.) : Tyrosinase Inhibitors from Crude Drugs, Biol. Pharm. Bull., +1, ,00ῌ,03.

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