Results: EPR measurements confirm the presence of complex bounds between Fe(III) and proteoglycans. Conclusion: Previous data showed a possible dependance between accumulated iron, proteoglycans, ferrireductive alpha-synuclein and Lewy bodies. We propose a mechanism of toxic iron accumulation in the brain in PD. This cyclic process of amplification is presented by onward steps. It is completed by our own observations into one cycle. The initiator of this vicious circle is probably an impirement of the equilibrium in the presence of useful amount of iron. Understanding these relations could bring new insights to the neurodegenerative disease.