Action of 2-Hydroxy-4,6-dimethoxyacetophenone Isolated from Sebastiania schottiana

Abstract

The inhibitory action of the major constituent of Sebastiania schottiana (Euphorbiaceae), 2-hydroxy-4,6-dimethoxyacetophenone (xanthoxyline) on contractions induced by agonists and electrical stimula tion of smooth and cardiac muscle preparations was analysed. Xanthoxyline (30 to 300 µM) inhibited contractions of the rat uterus, guinea-pig ileum, and urinary bladder induced by several agonists in a non-competitive, non-selective, concentration-related manner, with the IC₅₀'s ranging between 47 and 190 µM. Twitches evoked by electrical-stimulation of strips of guinea-pig longitudinal ileum, urinary bladder, dog ureter, and rat left atrium were also inhibited dose-dependently by cumulative additions of xanthoxyline (IC₅₀'s between 50 and 480 µM). Xanthoxyline was found to be a potent inhibitor of spontaneous contractions of the circular smooth muscle layer of the dog ureter, yielding an IC₅₀ of 54 µM. Repeated washing of all preparations completely reversed the inhibitory effects of xanthoxyline. Therefore, it appears that xanthoxyline induces a direct and non-selective inhibition of contractions triggered by agonists or electrical stimulation of smooth and cardiac muscle preparations. The elucidation of the mechanism(s) by which xanthoxyline induced muscle relaxation requires further investigations.

Key words

Sebastiania schottiana - xanthoxyline - antispasmodic - cardiac and smooth muscle