Biochemistry Department, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, SP, 13083-970, Brazil.
J Biomed Nanotechnol. 2009 Apr;5(2):192-201. doi: 10.1166/jbn.2009.1018.
Violacein is a compound obtained from Chromobacterium violaceum, a bacterium found in the Amazonian region. Violacein-loaded poly (D, L-lactide-co-glycolide) nanoparticles has a similar inhibitory effect evaluated by trypan blue assay on leukemic HL60 cells than the free form. However, the cytotoxic effects evaluated by phosphatase activity and MTT reduction assays were lower for the encapsulated form than for free violacein. Based on morphological changes, violacein and violacein entrapped in nanoparticles were found to induce terminal differentiation (assessed by nitro blue tetrazolium reduction) in HL60 cells. Thus, both formulations inhibit HL60 cell growth in vitro, partly by inducing cytotoxic effects and cell differentiation. Flow cytometric analysis of HL60 cells after treatment for 12 h showed that violacein-loaded PLGA induced apoptosis, with maximum cell death at a concentration of 2 microM. Violacein and violacein/PLGA induced opposite effects on the mitochondrial swelling which indicates altered mitochondrial function. The mitochondrial activity was also checked by flow cytometry studies. Labelled cells with the probe JC1 displayed a basal hypopolarized status of the mitochondria in treated cells. Based on morphological changes, alterations in phospholipid asymmetry and changes in mitochondrial polarization, violacein and nanoparticles containing violacein were found to trigger cell death by apoptosis. These methodologies are promising as diagnostic and mechanistic effects of nanoparticles in cell cultures.
紫红素是一种从 Chromobacterium violaceum 中提取的化合物，这种细菌存在于亚马逊地区。与游离形式相比，负载紫红素的聚（D，L-丙交酯-共-乙交酯）纳米粒子通过台盼蓝试验对白血病 HL60 细胞的抑制作用相似。然而，通过磷酸酶活性和 MTT 还原试验评估的细胞毒性作用，包封形式低于游离紫红素。基于形态变化，发现紫红素和包封在纳米粒子中的紫红素诱导 HL60 细胞的终末分化（通过硝基蓝四唑还原评估）。因此，两种制剂都部分通过诱导细胞毒性作用和细胞分化来抑制 HL60 细胞在体外的生长。用 HL60 细胞处理 12 小时后的流式细胞术分析表明，载有 PLGA 的紫红素诱导细胞凋亡，在 2 μM 的浓度下细胞死亡达到最大值。紫红素和紫红素/PLGA 对线粒体肿胀产生相反的影响，这表明线粒体功能发生改变。线粒体活性也通过流式细胞术研究进行了检查。用探针 JC1 标记的细胞显示处理细胞中线粒体的基础低极化状态。基于形态变化、磷脂不对称性的改变和线粒体极化的改变，发现紫红素和含有紫红素的纳米粒子通过细胞凋亡引发细胞死亡。这些方法在细胞培养中作为纳米粒子的诊断和机制效应很有前途。
