Synthesis, in vitro biological activity, hydrolytic stability and docking of new analogs of BIM-23052 containing halogenated amino acids.

One of the potent somatostatin analogs, BIM-23052 (DC-23-99) D-Phe-Phe-Phe-D-Trp-Lys-Thr-Phe-Thr-NH2, has established in vitro growth hormone inhibitory activity in nM concentrations. It is also characterized by high affinity to some somatostatin receptors which are largely distributed in the cell membranes of many tumor cells. Herein, we report the synthesis of a series of analogs of BIM-23052 containing halogenated Phe residues using standard solid-phase peptide method Fmoc/OtBu-strategy. The cytotoxic effects of the compounds were tested in vitro against two human tumor cell lines-breast cancer cell line and hepatocellular cancer cell line, as well as on human non-tumorigenic epithelial cell line. Analogs containing fluoro-phenylalanines are cytotoxic in µM range, as the analog containing Phe (2-F) showed better selectivity against human hepatocellular cancer cell line. The presented study also reveals that accumulation of halogenated Phe residues does not increase the cytotoxicity according to tested cell lines. The calculated selective index reveals different mechanisms of antitumor activity of the parent compound BIM-23052 and target halogenated analogs for examined breast tumor cell lines. All peptides tested have high antitumor activity against the HepG2 cell line (IC50 ≈ 100 µM and SI > 5) compared to breast cells. This is probably due to the high permeability of the cell membrane and the higher metabolic activity of hepatocytes. In silico docking studies confirmed that all obtained analogs bind well with the somatostatin receptors with preference to ssrt3 and ssrt5. All target compounds showed high hydrolytic stability at acid and neutral pH, which mimic physiological condition in stomach and human plasma.

Synthesis, Anticancer Activity, Docking Calculations and Hydrolytic Stability Studies of Bioconjugates of Monofluorenated Analogue of BIM- 23052.

BACKGROUND: The fight against cancer has started since its discovery and has not subsided to nowadays. Currently, the hybrid molecules have become a promising alternative to the standard chemotherapeutics for the treatment of multi-causal diseases, including cancers. OBJECTIVE: Herein, we report the synthesis, biological evaluation, mathematical docking calculations and hydrolytic stability of the new bioconjugates of monofluorinated analogues of BIM-23052, containing second pharmacophore naphthalimide, caffeic acid or the tripeptide Arg-Gly-Asp. METHODS: All new molecules are obtained using standard peptide synthesis on solid support. Anticancer potential is studied against a panel of tumor cell lines included human mammary carcinoma cell lines MCF-7 (ER+, PR+ and Her-2-); MDA-MB-231 (ER-, PR- and Her-2-), as well as cell lines BALB 3T3 (mouse embryonic fibroblasts) and MCF-10A (human breast epithelial cell line). RESULTS: The IC50 values found in the MCF-10A cell line assay were used to calculate the selective index (SI). The highest SI relative to MCF-7, with a value of 2.62 is shown by the compound Npht- Gly-D-Phe-Phe(4-F)-Phe-D-Trp-Lys-Thr-Phe-Thr-NH2. In MCF-10 cells, the weakest antiproliferative effect was caused by the same compound (IC50 = 622.9 ± 23.91 µM), which makes this analogue a good candidate for the new anticancer medical drug. Unfortunately, the hydrolytic stability studies reveal that this bioconjugate is the most unstable of hydrolysis under physiological conditions in the body. CONCLUSION: Even with lower anticancer activity and selectivity in comparison with Npht-Gly-DPhe- Phe(4-F)-Phe-D-Trp-Lys-Thr-Phe-Thr-NH2, the compound Arg-Gly-Asp-D-Phe-Phe(4-F)-Phe- D-Trp-Lys-Thr-Phe-Thr-NH2 is the best candidate between three investigated bioconjugates for practical application due to combination of activity and stability profiles. Mathematical docking calculation also reveals that synthesized bioconjugates show selectivity according to different somatostatin receptors on the surface of different cell lines.