Introduction: Chemotherapy, as a method of fighting cancer, has a number of significant limitations, so the search for new drugs to increase its effectiveness and reduce side effects is relevant. Another therapeutic approach, photodynamic therapy, is less invasive with minimal side effects; however, its spectrum of action does not go beyond the treatment of superficial tumors due to the low depth of light penetration into tissues. The objective of this work was to synthesize and study the biological activity of conjugates of derivatives of natural chlorines and doxorubicin containing thioketal (ROS-sensitive) and disulfide (GSH-sensitive) linkers designed for the controlled release directly into tumor cells and the tumor microenvironment.
Methods: NMR spectra were recorded on a Bruker DPX300 spectrometer. Absorption and fluorescence spectra of the photosensitizer solutions were recorded using a UV1800 spectrophotometer. Bioavailable micellar emulsions of the test compounds were analyzed and characterized using dynamic light scattering. Chromatography–mass spectrometry was carried out using a Dionex UltiMate RS 3000 ultra-high-performance liquid chromatograph with a mass spectrometry system.
Results: In this work, a number of compounds for combined photodynamic therapy were obtained. The structures of the prepared conjugates and the fragments formed during their cleavage under various conditions were analyzed using high-resolution chromatography–mass spectrometry. The destruction of labile linkers was studied using chromatographic/mass spectrometric monitoring. Biological studies in vitro were performed on the MCF-7 human breast adenocarcinoma cell line.
Conclusions: A strategy for the synthesis of chlorin–doxorubicin conjugates containing various linker molecules was proposed and developed. Studies of photoinduced and cytotoxic activity in vitro on human MCF-7 cells have demonstrated the high efficiency of the synthesized compounds. The confocal microscopy results demonstrated that conjugates with labile linkers showed chlorin internalization in the cytoplasm and doxorubicin in the nucleus, which indicates the effectiveness of the chosen strategy.
