Phenolic Compounds 3, 4, 5 - Hydroxy-n-phenyl Amide Of Tyrosol Anti-tumor Activity And Anti-oxidation Activity

The 3,4,5-trihydroxy-N-[2-p-tolylethyl]-benzamide(THTEB)is one of the derivatives of tyrosol,which is combined p-tyrosol with gallic acid by an amide bond.In this study,THTEB displayed significant antiproliferative effect on human cervical carcinoma(HeLa)cells.Cell cycle analysis revealed that THTEB could arrest HeLa cells on S phase with a concomitant decrease in the cell G₀/G₁ and G₂/M phase.According to the[³H]thymidine incorporation assay result,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 no effect on the RPA's ssDNA binding activity and the topoisomerase I mediated DNA relaxation activity,and it means that RPA and Topo I were not the target molecules on the inhibition of DNA replication.Furthermore,by using alkaline single-cell gel electrophoresis(comet assay),we found a severe DNA damage caused by THTEB.Among the possible causes of cancer,damage to DNA and other molecular molecules by reactive oxygen species(ROS),ranks high as a major culprit in the onset and development of the disease.During our course of developing anticancer drug,antioxidant activities of interest compounds are usually examined to illustrate the inner relationship of these two activities.To investigate the antioxidant activity of THTEB we used the DPPH,TEAC,lipid peroxidation assay and hydroxyl radical induced DNA damage assay.THTEB showed strong radical-scavenging activities in all of the five assays.It was found that THTEB had a stronger scavenging activity on the stable free radical 1,1-diphenyl-2-picrylhyrazyl(DPPH)and superoxide radical than ascorbic acid with IC₅₀value of～22.8 and -2.5μM,respectively. Trolox Equivalent Antioxidant Capacity(TEAC)value means a total antioxidant capacity of THTEB was about 0.6,which is also higher than L-ascorbic acid.THTEB on lipid peroxidation assay is weaker than well-known antioxidant compound 2,6-di-tertbutyl-4-methylphenol(BHT).Furthermore THTEB can significantly exhibited the protective activity against DNA strand scission by·OH on pBR322 DNA at an extremely low concentration as 4μM.In conclusion,these results suggest that THTEB had strong antioxidant activity as a radical-scavenger and could induce tumor cell cycle arrest in S phase correlate with DNA damage and DNA replication inhibition,but the target molecule of THTEB remains elusive. We suggested THTEB can be a valuable new addition to the list of anticancer chemotherapeutic agents.