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The comparison of free and melanin-bound lipofuscin isolated from pig iris

Jolanta Lodowska ¹, Ewa Chodurek ², Ludmiła Węglarz ¹, Daniel Wolny ², Sławomir Kurkiewicz ³, Leszek Krzyżanowski ⁴, Natalia Sakina ⁵, Barbara Bilińska ⁴, Mikhail Ostrovsky ⁵, Agnieszka Petela ⁶, Dariusz Dobrowolski ⁷

1. Medical University of Silesia, Department of Biochemistry, Narcyzow 1, Sosnowiec 41-200, Poland
2. Department of Biopharmacy, Medical University of Silesia, Narcyzów 1, Sosnowiec 41-200, Poland
3. Department of Instrumental Analysis, Medical University of Silesia, Narcyzów 1, Sosnowiec 41-200, Poland
4. Department of Physical Pharmacy, Medical University of Silesia, Jagiellońska 4, Sosnowiec 41-200, Poland
5. Institute of Biochemical Physics RAS (IBCP), Kosygin 4, Moscow 119991, Russian Federation
6. Department of Medical Physics, University of Silesia, Katowice 40-007, Poland
7. Ophthalmology Department, District Railway Hospital, Katowice 40-760, Poland

Abstract

Lipofuscin is a protein-lipid aggregate, which originates from incompletely degraded cell components, as a result of lysosomes dysfunction. This pigment, recognized as a marker of ageing can induce phototoxic reactions. Melanin, synthesized in the iris epithelium before birth and in stroma during the first weeks after birth has photo protective activity [1]. Structural modifications which occur in this biopolymer with ageing lead to the loss of its antioxidative properties or even to the toxic effects. Partially degraded melanin is probably bound to lipofuscin to form granulation called melanolipofuscin.

The aim of this study was to determine the chemical composition of free and melanine bound lipofuscin, isolated from pig iris.

This aim was realized by isolation of lipofuscin and melanolipofuscin from pig iris cells homogenate [2], followed by thermolysis at 770ºC and the analysis of obtained products by GC/MS.

In the pyrolytic profile of free and melanin-bound lipofuscin, the products of thermal degradation of melanins and proteins, such as derivatives of benzene, phenol, pyridine, pyrrole, indole and nitryls, have been identified. Aliphatic carbohydrates and derivatives of fatty acids have also been identified. The quantities of the products derived from melanins and proteins were much greater in melanolipofuscins compared to lipofuscin, where fatty acid derivatives were predominant compounds (44.6%). There was significant quantitative differentiation of pyrrole derivatives obtained from both lipofuscins and melanolipofuscins. These derivatives might have been products of thermolysis not only melanins but also of prolyl residues of lipofuscin protein component. Significant amounts of aliphatic carbohydrates detected during thermal degradation of biopolymers could probably result from decarboxylation of fatty acids or from melanin thermolysis as the alkyl radicals were generated from these compounds at high temperature and atmosphere of neutral gas.

[1] Kałużny B.J., Kałużny J.J., Okulistyka 2002: 2: 9-14

[2] Boulton M., Docchio F., Dayhaw-Barker P., Ramponi R., Cubeddu R., Vision Res. 1990: 30, 1291-1303

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The comparison of free and melanin-bound lipofuscin isolated from pig iris

Presentation: Poster at Zjazd Polskiego Towarzystwa Biochemicznego, Sympozjum V, by Jolanta Lodowska See On-line Journal of Zjazd Polskiego Towarzystwa Biochemicznego Submitted: 2007-04-12 12:42 Revised: 2009-06-07 00:44

Presentation: Poster at Zjazd Polskiego Towarzystwa Biochemicznego, Sympozjum V, by Jolanta Lodowska
See On-line Journal of Zjazd Polskiego Towarzystwa Biochemicznego

Submitted: 2007-04-12 12:42 Revised: 2009-06-07 00:44