Effect of Eupatorium arnottianum on Gastrointestinal Tract

Aims: Eupatorium arnottianum Griseb is used in popular medicine for gastric pains. So, the aim of this study was to investigate the possible spasmolytic effects of ethanolic and dichloromethanic extracts of the plant using preclinical methods.

Place and Duration of Study: Department of Pharmacology, School of Pharmacy and Biochemistry, Universidad de Buenos Aires, from September 2015 to May 2016. Methodology: The effects of Eupatorium arnottianum extracts and its isolated compounds were evaluated on isolated rat jejunum. Intestinal transit of charcoal meal after the administration of extract was determined and compared with the control group. Also, phytochemical study was performed.

Results: The extracts inhibited non competitively the cumulative concentration–response curves induced by acetylcholine (1.10-9–1.10-5 M), with similar inhibition at the highest concentration (2 mg/mL: 66.2±8.7% of inhibition for ethanolic extract and 61.5±10.5% of inhibition for dichlorometanic extract). Also, both extracts non-competitively inhibited the curve response concentration induced by CaCl2 (1.10-4 -3. 10-1 M) and significantly reduced the maximal response in a concentration-dependent manner. Furthermore, E. arnottianum (62, 125 and 250 mg/Kg, per oral) significantly decreased the propulsion of the charcoal meal through the gastrointestinal tract (68% of inhibition for 250 mg/Kg ethanolic extract, 42% of inhibition for 125 mg/Kg dichlorometanic extract). Finally, nepetin, the major compound of the ethanolic extract and two major compounds of dichlorometanic extract, jaceosidin and nepetin, reduced the maximal response of the acethylcholine in isolated jejunum (30 µg/mL: 75% of inhibition for jaceosidin and 89% of inhibition for nepetin).

Conclusion: The results of the present study could demonstrate that Eupatorium arnottianum plays a spasmolytic role in gastrointestinal motility by interfering in calcium influx. Also nepetin and jaceosidin, major components of ethanolic and dichlorometanic extracts could be responsible for these properties.