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Updated: Aug 20, 2026

Screening and Isolation of C-Glycoside-Cleaving Intestinal Bacteria
Published on: February 28, 2025
A bitter melon extract inhibits the P-glycoprotein activity in intestinal Caco-2 cells: monoglyceride as an active
Tomoko Konishi1, Hideo Satsu, Yasuo Hatsugai
1Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
P-glycoprotein (P-gp) is a 170 kDa membrane protein that belongs to the ATP-binding cassette (ABC) transporter superfamily. In normal tissues, P-gp functions as an ATP-dependent efflux pump that excretes highly hydrophobic xenobiotic compounds, playing an important role in protecting the cells/tissues from xenobiotics. In the present study, chemical substances that could directly modulate the intestinal P-gp activity were searched in vegetables and fruits. By using human intestinal epithelial Caco-2 cells as a model of the small intestinal cells, we observed that a bitter melon fraction extracted from 40% methanol showed the greatest increase of the rhodamine-123 accumulation by Caco-2 cells. Inhibitory compounds in the bitter melon fraction were then isolated by HPLC using Pegasil C4 and Pegasil ODS columns. The HPLC fraction having the highest activity was analyzed by (1)H-NMR and FAB-MS, and the active compound was identified as 1-monopalmitin. It is interesting that certain types of monoglyceride might be involved in the drug bioavailability by specifically inhibiting the efflux mediated by P-gp.
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