The present disclosure relates to polygalacturonan rhamnogalacturonan (PGRG1) compositions, as well as methods of making and methods of using said compositions in medicinally useful and pharmaceutically useful forms. Specifically, the present disclosure provides purified PGRG1 compositions isolated from roots of the Astragalus genus of plants, and more particularly from the species Astragalus membranaceus, as well as PGRG1 compositions having a weight average molecular weight of at least 40 kiloDaltons (kDa).
