Contribution to Immunochemical Analysis of Polysaccharides in Medicinal Plants

The kernels of Prunus mume, the medicinal plants, contain immunomodulating polysaccharide P-1 that is pectic, bioactive and extractable with sodium hydroxide. To study the immunochemical properties of P-1, an anti-P-1 antibody was prepared in rabbits. P-1 digested with pectinase was separated into three peaks by ion-exchange chromatography. The fraction that exhibited the strongest immunoreactivity with the antibody was P-1-3, the most acidic fraction containing GalA (54.42 %). The polysaccharide fraction extracted from the kernels by pectinase digestion instead of alkaline extraction showed little immunoreactivity with the anti-P-1 antibody. However, it became immunoreactive after sodium hydroxide treatment. These observations suggested that the majority of epitopes in P-1 were covered by sodium hydroxide-sensitive moieties. The localization of P-1 in kernels was investigated by immunohistoch-emical analysis. Sections of the kernels were treated with aqueous sodium hydroxide and then stained with an anti-P-1 antibody and anti- IgG labeled with peroxidase. Most P-1 was localized in the periphery of the sections and interfascicular tissues. Therefore, it was shown that the bioactive polysaccharide P-1 performed an important role in relation to the germination and growth of plants. This method could determine the distribution of pectic polysaccharide in plants.