Molecular Weight and Proposed Structure of the Angelica sinensis Polysaccharide‐iron Complex

The molecular weight and the proposed structure of the Angelica sinensis polysaccharide‐iron complex (APIC) were studied. Fourier transform infrared spectroscopy, X‐ray powder diffraction, differential scanning calorimetry, transmission electron microscopy, electron paramagnetic resonance, thermogravimetric analysis, atomic force microscopy, and gel filtration chromatography were used to characterize APIC, which is a macromolecule complex composed of Angelica sinensis polysaccharide (ASP) and iron. The structure of APIC was proposed to be a polynuclear ferrihydrite core chelated firmly by an encircling framework of ASP chains, forming a core molecule, which is surrounded by a removable outer protective sheath of colloidal ASP. And the molecular formula of APIC was proposed to be {[(Fe₂O₃·2.2H₂O)₁₀₄₃(ASP)₃₂](ASP)₁₂}, with MW=270000 Da.