Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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The oxidative pathway of dopamine metabolism in the human brain leads to the formation and accumulation of neuromelanin in the cytoplasm of most nigrostriatal dopaminergic neurons. The physiological significance of neuromelanin and its contribution to the neurodegenerative processes underlying Parkinson's disease are still controversial. Some data strongly suggest that neuromelanin of the human substantia nigra consist of indole-type and benzothiazine-type units derived from the oxidation of dopamine (DA) and 5-S-cysteinyldopamine (CysDA). The effect of model neuromelanins on Fe(II)/ascorbate-induced lipid peroxidation in micellea of linoleic acid and in lecithin liposomes was determined. Synthetic neuromelanis were obtained from dopamine, 5-S-cysteinyldopamine or from equimolar mixture of these precursors. TBA-test and RP-HPLC, used for measurements of primary and secondary oxidation products, showed that all melanins tested significantly suppressed peroxidation of both, linoleic acid and liposomal lecithin. The inhibitory effect of CysDA-melanin was lower than of DA/CysDA-melanin and DA-melanin. All the melanins were able to reduce linoleic acid hydroperoxides to their stable hydroxy derivatives. This suggested that model neuromelanins can act as chain-breaking antioxidants.

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Presentation Number SAwilczok0432
Keywords: neuromelanin, lipid, peroxidation