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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. [ABSTRACT FROM AUTHOR]

Peptides have been developed during the last decade as an alternative for delivery and targeting of drugs, and for the visualization of tumors. In contrast to the antibodies, the peptides are smaller and can be delivered to the cytoplasm by various mechanisms. RGD peptides have been developed as potent integrin ligands and antagonists that inhibit the adhesion and formation of tumor metastases or directly induce apoptosis by activating caspases. A series of short RGD mimetics and their conjugates are synthesized and their cytotoxic activity against four cancer cell lines is examined. RGD peptides modified by shorter homologues of with arginine (α-amino-4-guanidinobutyric acid (Agb) and α-amino-3-guanidino-propionic acid (Agp)) show an increase of the cytotoxic effect compared to that of the parent RGD peptide. [ABSTRACT FROM AUTHOR]

Hydrazones have versatile properties that make them promising for a range of possible applications. In this study, we examined a library of 17 aroylhydrazones derived from nicotinic acid hydrazide (1-12) and isonicotinic acid hydrazide (A-E) created by us for their biological activity. The antiproliferative activity of the compounds was investigated on non-tumour MCF-10A cells and cancer cell lines, MCF-7 and MDA-MB-231. Four compounds were selected as most active in cell growth inhibition of the tumour cell lines. These compounds, 5, 11, C and E, were tested on four additional cell lines: non-tumour BJ and cancer cell lines, HeLa, HepG2 and HT-29. Compounds 5 and E exhibited the highest selectivity index on cancer cell lines MDA-MB-231, HeLa and HepG2. High selectivity to MCF-7 cells was demonstrated with compound 5. Compound C was very selective to HepG2 cells as well as to MDA-MB-231 but to a lesser degree. Compound 11 showed selectivity against MDA-MB-231. The obtained results allow assessing the structure–activity relationship of the compounds and provide insight into the further development of this group of aroylhydrazones as more potent and selective anti-neoplastic agents. [ABSTRACT FROM AUTHOR]