Synthesis, In Silico Logp Study, and In Vitro Analgesic Activity of Analogs of Tetrapeptide FELL

BACKGROUND

The inflammatory process represents a specific response of the organism's immune system. More often, it is related to the rising pain in the affected area. Independently of its origin, pain represents a complex and multidimensional acute or chronic subjective unpleasant perception. Currently, medical doctors prescribe various analgesics for pain treatment, but unfortunately, many of them have adverse effects or are not strong enough to suppress the pain. Thus, the search for new pain-relieving medical drugs continues.

METHODS

New tetrapeptide analogs of FELL with a generaanalgesic-Glu-X3-X4-Z, where X = Nle, Ile, or Val and Z = NH2 or COOH, containing different hydrophobic amino acids at positions 3 and 4, were synthesized by means of standard solid-phase peptide synthesis using the Fmoc/OtBu strategy in order to study the influence of structure and hydrophobicity on the analgesic activity. The purity of all compounds was monitored by HPLC, and their structures were proven by ESI-MS. Logp values (partition coefficient in octanol/water) for FELL analogs were calculated. Analgesic activity was examined by the Paw-pressure test (Randall-Selitto test).

RESULTS

The obtained results reveal that Leu is the best choice as a hydrophobic amino acid in the FELL structure.

CONCLUSIONS

The best analgesic activity is found in the parent compound FELL and its C-terminal amide analog.

Novel Fluorescent Benzimidazole-Hydrazone-Loaded Micellar Carriers for Controlled Release: Impact on Cell Toxicity, Nuclear and Microtubule Alterations in Breast Cancer Cells

Fluorescent micellar carriers with controlled release of a novel anticancer drug were developed to enable intracellular imaging and cancer treatment simultaneously. The nanosized fluorescent micellar systems were embedded with a novel anticancer drug via the self-assembling behavior of well-defined block copolymers based on amphiphilic poly(acrylic acid)-block-poly(n-butyl acrylate) (PAA-b-PnBA) copolymer obtained by Atom Transfer Radical Polymerization (ATRP) and hydrophobic anticancer benzimidazole-hydrazone drug (BzH). Through this method, well-defined nanosized fluorescent micelles were obtained consisting of a hydrophilic PAA shell and a hydrophobic PnBA core embedded with the BzH drug due to the hydrophobic interactions, thus reaching very high encapsulation efficiency. The size, morphology, and fluorescent properties of blank and drug-loaded micelles were investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescent spectroscopy, respectively. Additionally, after 72 h of incubation, drug-loaded micelles released 3.25 μM of BzH, which was spectrophotometrically determined. The BzH drug-loaded micelles were found to exhibit enhanced antiproliferative and cytotoxic effects on MDA-MB-231 cells, with long-lasting effects on microtubule organization, with apoptotic alterations and preferential localization in the perinuclear space of cancer cells. In contrast, the antitumor effect of BzH alone or incorporated in micelles on non-cancerous cells MCF-10A was relatively weak.