Astragalus membranaceus

Astragalus membranaceus root contains bioactive compounds across several major classes. Primary active constituents include polysaccharides (astragalans, APS) at approximately 20–30% dry weight, which are the dominant immunomodulatory components. Saponins (astragalosides I–IV, cycloastragenol, acetylastragaloside) are present at approximately 0.5–2% dry weight, with astragaloside IV being the most studied at concentrations of roughly 0.02–0.1% in standardized extracts. Flavonoids (calycosin, formononetin, calycosin-7-glucoside, ononin) are present at approximately 0.5–1.5% dry weight. Protein content in dried root is approximately 10–12% dry weight, including gamma-aminobutyric acid (GABA) and various free amino acids such as asparagine (~1.2%) and canavanine traces. Crude fiber content is approximately 15–20% dry weight, primarily as cellulose and pectin-like polysaccharides. Mineral content includes potassium (~12 mg/g dry weight), calcium (~3.5 mg/g), magnesium (~2.1 mg/g), iron (~0.2 mg/g), zinc (~0.04 mg/g), and selenium (~0.003 mg/g, variable by soil origin). Trace amounts of choline and betaine are also reported. Bioavailability notes: Astragaloside IV has poor oral bioavailability (~3–5%) due to its large molecular size and limited intestinal absorption; cycloastragenol, its aglycone, shows improved bioavailability (~10–20%) and is the form that reaches systemic circulation more effectively. Polysaccharides act largely in the gut and are minimally absorbed intact, exerting local and systemic immune effects via gut-associated lymphoid tissue. Flavonoids such as calycosin undergo intestinal metabolism to active metabolites with moderate bioavailability (~15–30%). Lipid content is low, approximately 1–3% dry weight, consisting primarily of linoleic acid and palmitic acid.