Prabhakaran C, Kumar P, Panneerselvam N, Rajesh S, Shanmugam G
Department of Biochemistry and Cancer Biology, School of Biological Sciences, Madurai Kamaraj University, India.
Mutagenesis. 1996 Nov;11(6):553-7. doi: 10.1093/mutage/11.6.553.
Cleistanthin B, one of the toxic constituents of Cleistanthus collinus, was found to be cytotoxic to normal and tumour cells. In comparison with normal cells, tumour cells were sensitive to lower doses of toxin. The 50% growth inhibition (GI50) values for normal cell lines were from 2 x 10(-5) to 4.7 x 10(-4) M and for tumour cells the values ranged from 1.6 x 10(-6) to 4 x 10(-5) M. Short exposure (30 min) of Chinese hamster ovary (CHO) cells to cleistanthin B at 1-6 micrograms/ml resulted in extensive chromatid and isochromatid breaks and gaps. However there was no significant increase in cell death and DNA strand breaks in cells treated under the above conditions. Cleistanthin B induced micronucleus formation in cultured lymphocytes in a dose-dependent manner. CHO cells treated with high doses of cleistanthin B showed a decrease in cell viability and a concomitant increase in DNA strand-breaks. The cell death appears to be due to apoptosis since nucleosome-like ladders were observed in the treated cells when the DNA was electrophorized in agarose gels.
叶下珠素B是叶下珠的毒性成分之一，被发现对正常细胞和肿瘤细胞均具有细胞毒性。与正常细胞相比，肿瘤细胞对较低剂量的毒素更为敏感。正常细胞系的50%生长抑制（GI50）值为2×10⁻⁵至4.7×10⁻⁴M，而肿瘤细胞的该值范围为1.6×10⁻⁶至4×10⁻⁵M。将中国仓鼠卵巢（CHO）细胞短时间（30分钟）暴露于浓度为1 - 6微克/毫升的叶下珠素B中，会导致大量染色单体和等臂染色单体断裂及间隙。然而，在上述条件下处理的细胞中，细胞死亡和DNA链断裂并未显著增加。叶下珠素B以剂量依赖方式诱导培养的淋巴细胞形成微核。用高剂量叶下珠素B处理的CHO细胞显示细胞活力下降，同时DNA链断裂增加。细胞死亡似乎是由于凋亡，因为当在琼脂糖凝胶中对DNA进行电泳时，在处理过的细胞中观察到了核小体样梯带。
