Design and Synthesis of Actin-Targeting 10-Phenoxy Cytochalasan Analogues: Balancing Cytotoxicity and Migrastatic Activity

Cytochalasans are actin polymerization inhibitors with potent migrastatic activity, but their potential therapeutic use is limited by their cytotoxicity. Here, we describe a modular late-stage approach that introduces unprecedented 10-phenoxy substituents into the cytochalasan scaffold via a Mitsunobu reaction. A series of ten 10-phenoxycytochalasan analogues was synthesized and evaluated for actin polymerization inhibition, migrastatic activity, and cytotoxicity (BLM, MRC-5, and HaCaT). At 10 μM concentration, several 7-hydroxy-10-phenoxycytochalasans (12a,d-g) significantly inhibited actin polymerization in vitro and showed migrastatic effects in a spheroid invasion assay. Para-substituents of the phenoxy group modulated cytotoxicity without compromising actin polymerization inhibition or migrastatic activity. In contrast, lipophilic ortho-substituents predicted by molecular docking to enhance actin binding failed to manifest migrastatic activity, underscoring the limitations of the molecular docking with this type of compounds. These findings demonstrate that migrastatic and cytotoxic effects can be decoupled in cytochalasan analogues and highlight 10-phenoxy substitution as a promising strategy toward noncytotoxic migrastatic agents.