Immunoreactivity of the Cold Water Extract of Royal Sun Culinary-Medicinal Mushroom, Agaricus brasiliensis Strain KA21 (Agaricomycetes), Assessed by Immunoglobulin Preparations for Intravenous Injection

The royal sun medicinal mushroom, Agaricus brasiliensis, is a health food material that helps to improve quality of life. A. brasiliensis has long been used as a tea by extraction with cold and hot water. Our group has been investigating the immunopharmacological activities of the A. brasiliensis KA21 strain, which is cultivated outdoors. We prepared cold water (AgCWE) and hot water (AgHWE) extracts of this strain. AgCWE contained a larger proportion of proteins, including enzymes, and showed a brownish color during the extraction process. By contrast, chemical and immunochemical analyses revealed that AgHWE contained large amounts of beta-1,3-/1,6-glucans. In an attempt to elucidate the immunochemical characteristics of AgCWE, reactivities to immunoglobulin (Ig) preparations for intravenous injection were analyzed and compared with standard materials. To characterize brownish high-molecular weight components, standard phenol compounds such as caffeic acid (CA), trans-ferulic acid (FA), and coumaric acid (CouA) were polymerized to brownish polymerized polyphenols (PPPs) (i.e., polymerized CA, polymerized FA, and polymerized CouA) by laccase or peroxidase. The results obtained revealed that intravenous Ig reacted with all PPPs and PPPs cross-reacted with AgCWE and AgHWE. The isotype of the anti-PPP antibody was found to be IgG1, in contrast to that of the beta-glucan antibody, which was mainly IgG2. These results strongly suggest that A. brasiliensis extracts contain immunoreactive components against various classes of Igs.