On the pro‐oxidant effects of haemozoin

FEBS Letters

Silva, José R⁵  de Oliveira, Marco A⁵  Pinhal, Nelson M³  Oliveira, Marcus F¹  Vugman, Ney V³  Sousa, João J.F³  Oliveira, Pedro L¹  de Souza, Wanderley²  Attias, Márcia²  Timm, Bruno L¹  Miranda, Kildare²  Dansa-Petretski, Marı́lvia⁵  Machado, Ednildo A⁴ 

[1] Departamento de Bioquı́mica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowsky, s/n, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ 21941-590, Brazil;Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofı́sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil;Instituto de Fı́sica, Departamento de Fı́sica dos Sólidos, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil;Laboratório de Entomologia Médica, Instituto de Biofı́sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil;Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil

关键词: Haemozoin;    Haem;    Free radical;    Oxidative stress;   

DOI  :  10.1016/S0014-5793(02)02243-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Haemozoin (Hz) is a haem aggregate produced in some blood-feeding organisms. There is a general belief that Hz formation would be a protective mechanism against haem toxicity. Here we show that when aggregated into Hz, haem is less deleterious than its free form. When haem was added to phosphatidylcholine (PC) liposomes, there was an intense stimulation of oxygen consumption, which did not occur when Hz was incubated with the same preparation. Evaluation of oxygen radical attack to lipids, by measurement of thiobarbituric acid reactive substances (TBARS), showed significantly lower levels of lipid peroxidation in samples containing PC liposomes incubated with Hz than with haem. However, TBARS production induced by Hz was much higher when using 2-deoxyribose (2-DR) as substrate, than with PC liposomes. Spin-trapping analysis by electron paramagnetic resonance (EPR) of Hz and tert-butylhydroperoxide (tert-BuOOH) showed that production of methoxyl and tert-butoxyl radicals was only slightly reduced compared to what was observed with haem. Interestingly, when large Hz crystals were used in 2-DR TBARS assays and tert-BuOOH EPR experiments, the pro-oxidant effects of Hz were strongly reduced. Moreover, increasing concentrations of Hz did not induce erythrocyte lysis, as occurred with haem. Thus, the reduced capacity of Hz to impose radical damage seems to result from steric hindrance of substrates to access the aggregated haem, that becomes less available to participate in redox reactions.

【 授权许可】

Unknown