Abstract
In this study, the interactions of two benzoxanthones 1,3-dihydroxy-12H-benzo[b]xanthen-12-one (1) and 9,11-dihydroxy-12H-benzo[a]xanthen-12-one (2) with calf thymus DNA (ct DNA) have been investigated by absorption spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy and viscosity measurements. Experimental results suggested an intercalative mode with DNA for the two compounds; Furthermore, the binding affinity with DNA of 1 bearing linearly fused aromatic rings was higher than that of 2 bearing angularly fused aromatic rings according to the calculated binding constant values. In addition, three cell lines, the human cervical cancer cell line (HeLa), human hepatocellular liver carcinoma cell line (HepG2) and human normal liver cell line (L02) were used to evaluate the cytotoxic activities of the two benzoxanthones in vitro. As the results, they showed significant cytotoxic activity against the tumor cell lines HeLa and HepG2, but weak cytotoxic activity against normal liver cell line L02.
