Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide

TY - JOUR

T1 - Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide

AU - Smith, R. A W

AU - Garrett, B.

AU - Naqvi, K. R.

AU - Fülöp, A.

AU - Godfrey, S. P.

AU - Marsh, J. M.

AU - Chechik, V.

N1 - © 2017, Elsevier Inc. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2017/7/1

Y1 - 2017/7/1

N2 - This work aims to determine the roles of reactive oxygen species HO∙ and HO2 − in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO2 − and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO2 −. Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO2 −. In this manner the efficiency of the roles of both species is maximised.

AB - This work aims to determine the roles of reactive oxygen species HO∙ and HO2 − in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO2 − and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO2 −. Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO2 −. In this manner the efficiency of the roles of both species is maximised.

KW - Fenton chemistry

KW - Hydrogen peroxide

KW - Hydroxyl radical

KW - Melanin bleaching

KW - Reactive oxygen species

KW - Superoxide

UR - http://www.scopus.com/inward/record.url?scp=85015838120&partnerID=8YFLogxK

U2 - 10.1016/j.freeradbiomed.2017.03.014

DO - 10.1016/j.freeradbiomed.2017.03.014

M3 - Article

AN - SCOPUS:85015838120

SN - 0891-5849

VL - 108

SP - 110

EP - 117

JO - Free Radical Biology and Medicine

JF - Free Radical Biology and Medicine

ER -