ABSTRACT
This work aims to determine the roles of reactive oxygen species HOâ and HO2- in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HOâ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO2- and HOâ 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, HOâ and HO2-. Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HOâ 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.
Subject(s)
Fish Proteins/metabolism , Hair/metabolism , Hydrogen Peroxide/metabolism , Melanins/metabolism , Melanocytes/physiology , Melanosomes/metabolism , Animals , Antacids/chemistry , Humans , Hydrogen Peroxide/chemistry , Iron/chemistry , Oxidation-Reduction , Reactive Oxygen Species/metabolism , Sepia , Skin PigmentationABSTRACT
The 24th annual symposium of the International Isotope Society's United Kingdom Group took place at the Møller Centre, Churchill College, Cambridge, UK on Friday 6th November 2015. The meeting was attended by 77 delegates from academia and industry, the life sciences, chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral presentations, short 'flash' presentations in association with particular posters and poster presentations. The scientific areas covered included isotopic synthesis, regulatory issues, applications of labelled compounds in imaging, isotopic separation and novel chemistry with potential implications for isotopic synthesis. Both short-lived and long-lived isotopes were represented, as were stable isotopes. The symposium was divided into a morning session chaired by Dr Rebekka Hueting (University of Oxford, UK) and afternoon sessions chaired by Dr Sofia Pascu (University of Bath, UK) and by Dr Alan Dowling (Syngenta, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, UK).
