We have isolated three macromolecular compounds from the leaves of the species which form the collective drug Plantaginis folium: Plantago major L. (PM), Plantago media L. (Pm) and Plantago lanceolata L. (Pl). These macromolecules were submitted to chemical and pharmacological studies. Preliminary chemical studies emphasized the fact that each macromolecular compound consisted of protein and polysaccharide fractions. The chemical studies of the protein fractions were based on the quantification of the nitrogen content, quantification of the whole amount of proteins and water-soluble proteins. For the study of the polysaccharide fractions we used different techniques such as: anion-exchange column chromatography, high pressure-gel permeation chromatography, gel filtration chromatography, thin layer chromatography and Blumenkrantz photocolorimteric method for the quantification of uronic acids. These chemical studies emphasized the fact that PM, Pm and Pl has different chemical compositions. Pl contains the highest amount of protein substances (3.740% N, 21.3522% proteins and 6.6369% water-soluble proteins). PM, Pm and Pl are made of polysaccharide components with different molecular weights, different chemical and optical properties and different amounts of ironic acids. The highest amount of uronic acids was determined for Pl (2.5408%). PM, Pm and Pl were further submitted to the following pharmacological trials: a preliminary screening for the evaluation of possible immunostimulating effects and another one for the evaluation of the influence upon mechanisms belonging to the non-specific immunity defence (phagocytosis, haemolytic activity of the seric complement). The immunostimulating effects developed by Pm and Pl were higher than the effects developed by PM.
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