National Laboratory of Experimental Oncology, Federal University of Ceará, CEP 60430-270, Fortaleza, CE, Brazil.
Pharm Biol. 2012 Aug;50(8):980-93. doi: 10.3109/13880209.2012.654921.
Quassinoids are biologically active secondary metabolites found exclusively in the Simaroubaceae family of plants. These compounds generally present important biological properties, including cytotoxic and antitumor properties.
In the present study, the cytotoxic effects of neosergeolide, a quassinoid isolated from Picrolemma sprucei Hook. f., were evaluated in human promyelocytic leukemia cells (HL-60).
Cytotoxicity and antiproliferative effects were evaluated by the MTT assay, May-Grünwald-Giemsa's staining, BrdU incorporation test, and flow cytometry procedures. The comet assay and micronuclei analysis were applied to determine the genotoxic and mutagenic potential of neosergeolide.
After 24 h exposure, neosergeolide strongly inhibited cancer cell proliferation (IC₅₀ 0.1 µM), and its activity seemed to be selective to tumor cells because it had no antiproliferative effect on human peripheral blood mononuclear cells (PBMC) at tested concentrations. Apoptosis was induced at submicromolar concentrations (0.05, 0.1, and 0.2 µM) as evidenced by morphological changes, mitochondrial depolarization, phosphatidylserine externalization, caspases activation, and internucleosomal DNA fragmentation. Additionally, neosergeolide effects were prevented by cyclosporine A (CsA), an inhibitor of the mitochondrial permeability transition (MPT) pore, which reinforced the participation of intrinsic pathways in the apoptotic process induced by this natural quassinoid. Direct DNA damage was further confirmed by comet assay and cytokinesis-block micronucleus test.
The present study provided experimental evidence to support the underlying mechanism of action involved in the neosergeolide-mediated apoptosis. In addition, no antiproliferative effect or DNA damage effect of neosergeolide was evident in PBMC, highlighting its therapeutic potential.
苦木苦味素是一种生物活性的次级代谢产物，仅存在于楝科植物中。这些化合物通常具有重要的生物学特性，包括细胞毒性和抗肿瘤特性。
本研究评估了从 Picrolemma sprucei Hook. f. 中分离得到的新蛇根苦素（neosergeolide）对人早幼粒细胞白血病细胞（HL-60）的细胞毒性作用。
通过 MTT 法、May-Grünwald-Giemsa 染色、BrdU 掺入试验和流式细胞术程序评估细胞毒性和抗增殖作用。应用彗星试验和微核分析来确定 neosergeolide 的遗传毒性和致突变性。
暴露 24 小时后，neosergeolide 强烈抑制癌细胞增殖（IC₅₀ 0.1 μM），其活性似乎对肿瘤细胞具有选择性，因为在测试浓度下对人外周血单核细胞（PBMC）没有抗增殖作用。在亚微摩尔浓度（0.05、0.1 和 0.2 μM）下诱导凋亡，形态变化、线粒体去极化、磷脂酰丝氨酸外翻、半胱天冬酶激活和核小体间 DNA 片段化证明了这一点。此外，用环孢菌素 A（CsA）抑制线粒体通透性转换（MPT）孔，可预防 neosergeolide 的作用，这加强了这种天然苦木苦味素诱导凋亡过程中固有途径的参与。彗星试验和胞质分裂阻断微核试验进一步证实了直接的 DNA 损伤。
本研究提供了实验证据，支持了 neosergeolide 介导的凋亡所涉及的作用机制。此外，neosergeolide 在 PBMC 中没有表现出抗增殖作用或 DNA 损伤作用，突出了其治疗潜力。
