Benzoxaboroles as dynamic covalent receptors for bioconjugation and transport of nucleosides and related drugs: Proof of action in HeLa cells.

In this work we describe not previously explored binding studies on the reversible interaction of benzoxaborole with ligands of medical and pharmaceutical interest such as nucleosidic drugs gemcitabine and capecitabine, as well as the hydrophobic chemotherapeutic doxorubicin. We include functional derivatives of benzoxaborole such as a near infrared fluorescent boronolectine, Cy-Bx, The dynamic covalent interaction in physiological conditions was assessed by spectroscopic techniques yielding moderate to high binding affinities. The cytotoxic activity of the drugs upon conjugation to the boronolectins was evaluated revealing significant influence of the bioconjugation status on the cellular viability. The availability of the conjugate for cellular uptake and localization in the model cancer cell line HeLa was assessed by fluorescence imaging. Benzoxaborole and the fluorescent boronolectin Cy-Bx, proved to be versatile conjugation tools for 1,2 and 1,3-diol containing pharmacophores as well as bioisosteric forms such as 1,2-hydroxyamino, envisioning these small boronolectins as components in systems for drug release with tracking capability.