Santos A E, Laranjinha J A, Almeida L M
Laboratório de Bioquímica, Faculdade de Farmácia and Centro de Neurociências, Universidade de Coimbra, Portugal.
Photochem Photobiol. 1998 Apr;67(4):378-85.
The interactions of sulfonated chloroaluminum phthalocyanine (AlPcSn) with human low-density lipoproteins (LDL) were studied in vitro in human plasma and in an isolated LDL fraction, in order to understand the potential effects of the sensitizer against LDL. The AlPcSn added to plasma distributes in all lipoproteins as observed by the drastic color changes of the separated fractions by ultracentrifugation. In isolated LDL, incubation with AlPcSn causes fluorescence quenching of the apoprotein tryptophan residues. Furthermore, AlPcSn incorporates in liposomes, with a lipid composition similar to the external monolayer of human LDL, as indicated by absorbance spectroscopy. The photosensitizing properties of AlPcSn in LDL particles were studied on the basis of the fluorescence quenching of previously incorporated cis-parinaric acid (PnA), used as an oxidation probe, and of O2 consumption. The photooxidation of either PnA or LDL lipids is highly dependent on irradiation time and on the dye concentration. Moreover, photooxidation of LDL proceeds only during the illumination period. After stopping the illumination and upon addition of Cu2+ to the LDL solution, the oxidative rate is resumed, probably due to hydroperoxide cleavage and formation of species able to propagate the oxidative reaction. Thus, our data indicate that AlPcSn distributes in human plasma lipoproteins and, in isolated LDL, it can interact either with the lipid phase or the apoprotein. The photooxidation of LDL induced by AlPcSn seems to involve singlet oxygen as the main reactive species in the degradative process.
为了解磺化氯铝酞菁（AlPcSn）对低密度脂蛋白（LDL）的潜在影响，在人体血浆和分离的LDL组分中对其与人类低密度脂蛋白的相互作用进行了体外研究。通过超速离心分离的组分颜色急剧变化观察到，添加到血浆中的AlPcSn分布于所有脂蛋白中。在分离的LDL中，与AlPcSn孵育会导致载脂蛋白色氨酸残基的荧光猝灭。此外，吸收光谱表明，AlPcSn可掺入脂质体中，其脂质组成与人LDL的外层单分子层相似。基于先前掺入的顺式十八碳四烯酸（PnA）作为氧化探针的荧光猝灭以及氧气消耗，研究了AlPcSn在LDL颗粒中的光敏特性。PnA或LDL脂质的光氧化高度依赖于照射时间和染料浓度。此外，LDL的光氧化仅在光照期间进行。停止光照并向LDL溶液中添加Cu2+后，氧化速率恢复，这可能是由于氢过氧化物的裂解以及能够传播氧化反应的物质的形成。因此，我们的数据表明，AlPcSn分布于人体血浆脂蛋白中，并且在分离的LDL中，它可以与脂质相或载脂蛋白相互作用。AlPcSn诱导的LDL光氧化似乎涉及单线态氧作为降解过程中的主要反应物种。
