Oxidative destruction of human RPE melanosomes induced by superoxide radicals leads to the formation of reactive aldehydes and ketones

Oxidative destruction of the natural pigment melanin leads to a decrease in its concentration in the cell, a decrease of antioxidant properties and the accumulation of products that exhibit prooxidant activity. This work shows for the first time that oxidative destruction of melanosomes from human retinal pigment epithelium (RPE) cells induced by superoxide radicals results in the formation of toxic carbonyl compounds, namely aldehydes and ketones. Analysis of the products of oxidative degradation of melanosomes was performed by absorption and fluorescence spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS). It has been shown the water-soluble products of oxidative destruction of RPE melanosomes induce proteins modification with the formation of fluorescent Schiff bases. It is assumed that carbonyl products of oxidative destruction of melanosomes can have a toxic effect on RPE
cells, which is important for understanding the mechanisms of development of retina senile degenerative diseases.