Unexpected cytotoxicity of a triisopropylsilylated syringaldehyde derived cinnamic acid amide

Abstract

<jats:p>A small series of substituted cinnamic acid amides was prepared and screened for their cytotoxic activity. As a rather astonishing and unprecedented result, compound 5 holding a triisopropylsilyl (TIPS) protecting group at position 4 of the aromatic ring was highly cytotoxic (EC50 = 3.2 mM for HT29 human colon adenocarcinoma cells) while analogs with a methoxy or hydroxyl group at this position were of low cytotoxicity or not cytotoxic at all.</jats:p>