Antiproliferation of HeLa cells by 3,4,5-trihydroxy-N-[2-p-tolylethyl]-benzamide is associated with induction of DNA damage and inhibition of DNA replication.

The compound 3,4,5-trihydroxy-N-[2-p-tolylethyl]-benzamide (THTEB) is one of the derivatives of tyrosol, which is p-tyrosol combined with gallic acid by an amide bond. In this study, THTEB displayed a significant antiproliferative effect on human cervical carcinoma (HeLa) cells. Cell cycle analysis revealed that THTEB could arrest HeLa cells in the S phase with a concomitant decrease in the cells' G0/G1 and G2/M phases. According to the [3H]thymidine incorporation assay results, we found that THTEB could inhibit DNA replication, which suggests that THTEB-induced S phase arrest might be the direct result of blocked DNA synthesis. However, THTEB had very weak effect on replication protein A (RPA)'s ssDNA binding activity and the topoisomerase I (topo I)-mediated DNA relaxation activity, signifying that RPA and topo I were not the main target molecules in the inhibition of DNA replication. Furthermore, by using alkaline single-cell gel electrophoresis (comet assay), we found severe DNA damage caused by THTEB. In conclusion, these results suggest that THTEB could induce tumor cell antiproliferation correlated with DNA damage and DNA replication inhibition, but the target molecule of THTEB remains elusive.