108 - Investigations for direct interactions between linoleic acid and melanin using observations of auto-luminescence

Abstract

Melanin is well-known as an important pigment for protecting various biological samples, such as human skin, hair, fruit, mushroom, from the harmful effects of oxidative stresses. Although photoprotective properties of melanin have been well documented, effects of melanin on reactive oxygen species (ROS) and other species have been reported in our previous studies [1,2]. It is confirmed that one of the mechanisms by which melanin protects UV-induced skin damage is likely quenching or scavenging activity against singlet oxygen and superoxide anion [1]. In addition, decompositions of lipid hydroperoxides are known to release excited triplet states of biomolecules composed with carbonyl groups. Ultra-weak photon emissions (UPEs) are important to monitor in the redox status because UPEs have been used as biomarkers for non-invasive imaging techniques. Because UPEs composed with various wave lengths, we investigated mechanisms of reactive species released from UPEs via chemical reactions of melanin by qualitative analysis and polychromatic spectral pattern analysis [2]. However, in spite of lipid-derivers free radicals, there are few studies mechanisms of cause damages through UPEs measurements of lipids. In the present studies, we investigated direct interactions between linoleic acid and melanin. Preliminary tests of UPE source exploration was demonstrated with auto-luminescence spectrum of melanin and coexistence with oxidized linoleic acid. Furthermore, increase in intensities of the auto-luminescence released from melanin with oxidized linoleic acid might be concentration-dependent. The findings suggested that excited triplet states of linoleic acid related with UPEs via chemical reactions could be a unique biomarker for making diagnoses on epidermis using the non-invasive images.