Unlocking the cytotoxic potential of Apocynaceae monoterpene indole and <i>bis</i> -indole alkaloids: a review

provided valparicine, kopsiarborine B, kopsiafrutine E, and kopsifine, all showing broad low- to sub-micromolar cytotoxicity. Structure-activity analyses link bis-indole frameworks and defined substitutions with enhanced potency. Although mechanistic evidence remains limited, reported pathways commonly involve apoptosis induction and cell-cycle arrest. Such findings reveal promising Apocynacae genera and structure-guided opportunities for anticancer drug development while underscoring the need for toxicity evaluation, pharmacokinetic profiling, and scalable production strategies.