1-Monopalmitin

Journal of the American Chemical Society, 2002, 72(10):4427-4432.

Molecular Rotation and Proton Transfer in the Solid Forms of 1-Monopalmitin and 1-Monostearin.[Reference: WebLink]

METHODS AND RESULTS:
The dielectric properties of 1-Monopalmitin and 1 -monostearin have been investigated at 100, 50, 25 and 5 kilocycles over a wide temperature range. Both compounds were observed to possess orientational freedom in both the α and sub-α forms. Strong frequency dependence of the dielectric constant and abnormally high conductivity, similar to that reported for the long-chain alcohols, were observed in the α forms of these compounds. The high conductivity has been attributed to a proton transfer mechanism facilitated by rotation of the chains about their long axes. The frequency dependence of the dielectric constant has been discussed in terms of a spatial polarization mechanism. The more stable β′ or β forms, isolated by special thermal treatment, possessed dielectric constants low enough for them to be considered as non-rotators.
CONCLUSIONS:
The sub-α forms have been studied and their dielectric behavior has been observed to vary considerably with previous thermal treatment. In order to account for the distribution of relaxation times observed in these forms, it has been suggested that the dipole orientation process is that of segment orientation. The results obtained here have been compared with previous X-ray diffraction and thermal studies.

Biofactors. 2004;22(1-4):71-4.

A bitter melon extract inhibits the P-glycoprotein activity in intestinal Caco-2 cells: monoglyceride as an active compound.[Pubmed: 15630255]

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.
METHODS AND RESULTS:
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.
CONCLUSIONS:
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.