Background: For studying the antioxidant activity a synthesized 1,3-bis(3-phenylpropyl-1)-
1,3-dihydro-2H-benzimidazol-2-imine hydrobromide (M1) has been chosen because of its most pronounced
antiproliferative effect (preliminary studies) to human colorectal cancer cell line HT-29, breast cancer cells
MDA-MB-231 and its nontoxicity to normal Lep 3, determined by means of MTS-test. It is believed that this suppressive
activity is due to its antioxidant capacity. Other two new linear somatostatin analogs which contain hydrophobic aminoacids
3c (D-Phe-c(Cys-Phe-D-Trp-Lys-Tle-Cys)-Thr-NH2) and 3L (Pro-Phe-Val-Tyr-Leu-Ile-D-Trp-Lys-Tle-Thr-NH2)
were tested for their toxicity to the same cells and all experiment substances were tested to activated macrophages.
Methods: the ROS-scavenging ability was examined (by HORAC and ORAC) using the same cells and the obtained results
confirmed a considerable suppressive capacity of the compounds.
Results: The compounds 3c and 3L exerted the most pronounced inhibition of the tumor cell vitality (up to 77%) at higher
concentrations and were not toxic to normal Lep-3 cells. After similar incubations with the substances activated human
peritoneal macrophages displayed also emission of ROS determined by chemiluminiscence (CL). Compound M1 showed
pronounced activity against activated peritoneal macrophages (PMA) mainly in the 100000x dilution in comparison to the
HORAC and ORAC; 3L is most effective only in the 100x concentration.
Conclusion: All tested compounds showed different suppressive activities depending on the cell line and on the substances
amount applied by performing HORAC / ORAC and CL investigations.