Abstract The antispasmodic activity of several xanthoxyline derivatives against acetylcholine- induced contraction of the guinea pig ileum was evaluated in vitro. The acetophenones with two methoxyl groups, mainly in the 3, 4 positions, exhibited potent antispasmodic activity. Modification of the hydroxyl group in xanthoxyline by the introduction of benzoyl, acetyl, or tosyl groups produced inactive compounds, whereas the introduction of benzyl or ρ- ...