5‐HT 3 and 5‐HT 4 receptors contribute to the anti‐motility effects of Garcinia buchananii bark extract in the guinea‐pig distal colon

• Published in: Neurogastroenterology and motility Vol. 24; no. 1
• Main Authors: Boakye, P. A., Stenkamp‐Strahm, C., Bhattarai, Y., Heckman, M. D., Brierley, S. M., Pasilis, S. P., Balemba, O. B.
• Format: Journal Article
• Language: English
• Published: 01.01.2012
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/j.1365-2982.2011.01807.x

Abstract Background  Garcinia buchananii bark extract is an anti‐motility diarrhea remedy. We investigated whether G. buchananii bark extract has components that reduce gastrointestinal peristaltic activity via 5‐HT 3 and 5‐HT 4 receptors. Methods  Aqueous G. buchananii extract was separated into fractions using preparative thin layer chromatography (PTLC), and major chemical components were identified using standard tests. The anti‐motility effects of the extract and its fractions (PTLC1‐5) were studied through pellet propulsion assays using isolated guinea‐pig distal colons. Key Results  Anti‐motility (PTLC1 & PTLC5) and pro‐motility (PTLC2) fractions were isolated from the extract. Flavonoids, steroids, alkaloids, tannins, and phenols were identified in the extract and PTLC1&5. The potency of the extract applied via the mucosal surface was reduced by 5‐HT, 5‐HT 3 receptor agonist RS‐56812, 5‐HT 4 receptor agonists cisapride and CJ‐033466, 5‐HT 3 receptor antagonist granisetron, and 5‐HT 4 receptor antagonist GR‐113808. The anti‐motility effects of the aqueous extract and PTLC1&5 when applied serosally were reversed by RS‐56812, cisapride, and CJ‐033466. The 5‐HT 3 receptor antagonists, granisetron and ondansetron, reduced the effects of the extract to an extent and completely reversed the anti‐motility effects of PTLC1&5. GR‐113808 inhibited the actions of the extract during the initial 10 min, but enhanced the extracts’ anti‐motility effects after 15 min. GR‐113808 augmented the anti‐motility activities of PTLC1 and PTLC5 by 30%. Conclusions & Inferences  These results indicate that the anti‐motility effects of G. buchananii aqueous extract are potentially mediated by compounds that affect 5‐HT 3 and 5‐HT 4 receptors. Identification and characterization of the bioactive compounds within G. buchananii could lead to the discovery of new non‐opiate anti‐diarrhea formulations.