Metal-containing components in medicinal plants. III. Manganese-containing components in Theae folium as oral magnetic resonance imaging contrast materials.

A manganese-containing component from the water-extract of Theae folium (green tea) was found to exert an augmentative effect in magnetic resonance imaging (MRI) contrast and may possibly be a manganese(II) complex with a pectin-like polysaccharide capable of shortening the spin-lattice relaxation time (T1) of water protons. Even though only the manganese(II) ion with S = 5/2 is active in T1-shortening ability, which should enhance contrast, complexation of this ion with the polysaccharide causes a marked increase in its activity. This manganese-containing pectin-like polysaccharides should prove useful as a low-toxic oral gastrointestinal contrast material in MRI.