Exceptional stability of the sugammadex-solasodine complex: Insights from experimental and theoretical studies

Sugammadex (SGM) is the first cyclodextrin (CD)-based selective relaxant binding agent. We investigated its ability to capture natural aminosteroid phytotoxins, and assessed its potential as an antidote for intoxication. Solasodine (SS), a toxic alkaloid from the Solanaceae family, was chosen as the model compound. Complexation was studied using nuclear magnetic resonance (NMR) spectroscopy, molecular modelling, and isothermal titration calorimetry (ITC). NMR in various D₂O/DMSO‑d₆ media revealed a particularly stable inclusion-type complex, identifying a slow exchange process between the CD and the aminosteroid along with a less significant fast exchange between DMSO and SGM. Using various NMR techniques, the structure and kinetic/thermodynamic parameters of the inclusion complex were explored. Theoretical calculations showed the secondary amino head of SS near the carboxylate ends of the SGM sidechains, facilitating intermolecular ionic interactions. ITC experiments in an aqueous environment provided K_a stability constants of 7.03 × 10⁶ M^-1 and 4.17 × 10⁶ M^-1 at 25 °C and 37 °C, respectively, similar to previously reported SGM complexes with aminosteroid neuromuscular blockers. Finally, SGM significantly increased cell survival and reduced SS toxicity in mHippoE-14 mouse hippocampal embryonic cells, supporting the hypothesis that SGM could act as an antidote to SS's toxic effects.