Figure 1. Selective killing effect of GBK in cancer cells.

(A) Chemical structure of GBK. (B) The purity of synthesized GBK was measured by high-performance liquid chromatography (HPLC). The sample of GBK had only one sharp peak at 12 min as a retention time on the HPLC chromatogram. GBK was HPLC-purified (~99% purity) before the treatment. (C, D) Normal human cells, including human mammary epithelial cells (MCF-10A), human skin fibroblast cells (HSF), human gastric mucosa cells (GES-1), and human lung epithelial cells (L132), African green monkey kidney cells (COS-7), and human cancer cell lines, including human mammary cancer cells (MCF-7 and SUM159), human gastric cancer cells (SGC-7901 and BGC-823), human liver cancer cells (HepG2) and human lung cancer cells (A549), were grown in 96-well plates and treated with GBK at 0–290 μg/ml for 48 h. Cell viability was measured by CCK-8 assay. (E) Normal and tumor cells were treated with GBK at 0–400 μg/ml for 14 days, and live cells were stained by crystal violet. ddH₂O was used as control. Columns show data expressed as means ± standard deviation (SD) of three independent experiments. *P < 0.05; **P < 0.01. (F) Cell viability of three human breast cancer cell lines treated with GBK was measured by CCK-8 assay. Independent experiments were repeated in triplicate; bars, SDs.