Figure 2.

Anticancer and radiosensitizing effects of phlorethols from C. costata (CcPh) on colony formation in human colorectal carcinoma cells. HT-29 and HCT 116 cells (2.4 × 10⁴) were treated with (A,D) CcPh (10, 20, and 40 µg/mL) or (B,E) X-ray (2, 4, 8, and 10 Gy) or (C,F) a combination of X-ray radiation (2 Gy) and CcPh (5, 10, and 20 µg/mL) and subcultured onto Basal Medium Eagle BME soft agar and incubated for 2 weeks. The number of colonies was calculated using the ImageJ software bundled with 64-bit Java 1.8.0_112 (NIH, Bethesda, Maryland, USA). All experiments were repeated at least three times in each group. Results are expressed as the mean ± standard deviation (SD). The asterisk (*) indicates a significant decrease in the number of colonies of cancer cells treated with CcPh or X-ray compared to PBS-treated cells or CcPh in combination with X-ray compared to irradiated cells (** p < 0.01, *** p < 0.001).