Astragalus Root
Astragali Radix
Astragalus Root is the root of Astragalus membranaceus Bunge or Astragalus mongholicus Bunge (Leguminosae).
Description:
Nearly cylindrical root, 30 - 100 cm in length, 0.7 - 2 cm in diameter, with small bases of lateral root dispersed on the surface, twisted near the crown; externally light grayish yellow to light yellow-brown, and covered with irregular, dispersed longitudinal wrinkles and horizontal lenticel-like patterns; difficult to break; fractured surface fibrous. Under a magnifying glass, a transverse section reveals an outer layer composed of periderm; cortex light yellowish white, xylem light yellow, and zone near the cambium somewhat brown in color; thickness of cortex from about one-third to one-half of the diameter of xylem; white medullary ray from xylem to cortex in thin root, but often appearing as radiating cracks in thick root; usually pith unobservable.
Odor, slight; taste, sweet.
Identification:
Put 1 g of pulverized Astragalus Root in a glass-stoppered centrifuge tube, add 5 mL of potassium hydroxide TS and 5 mL acetonitrile, and stop the vial tightly. After shaking this for 10 minutes, centrifuge, and use the upper layer as the sample solution. Separately, dissolve 1 mg of astragaloside IV for thin-layer chromatography in 2 mL of methanol, and use this solution as the standard solution. Perform the test with these solutions as directed under Thin-layer Chromatography. Spot 10 μL of the sample solution and standard solution on a plate of silica gel for thin-layer chromatography. Develop the plate with a mixture of ethyl acetate, methanol and water (20:5:4) to a distance of about 10 cm, and air-dry the plate. Spray evenly diluted sulfuric acid on the plate, heat at 105oC for 5 minutes, and examine under ultraviolet light (main wavelength: 365 nm): one of the spot among the several spots from the sample solution has the same color tone and Rf value with the brownish yellow fluorescent spot from the standard solution.
Purity:
(1) Root of Hedysarum species and others.Under a microscope, a vertical section of Astragalus Root reveals no crystal fiber containing solitary crystals of calcium oxalate outside the fiber bundle.
(2) Heavy metals. Proceed with 3.0 g of pulverized Astragalus Root according to Method 3, and perform the test. Prepare the control solution with 3.0 mL of Standard Lead Solution (not more than 10 ppm).
(3) Arsenic. Prepare the test solution with 0.40 g of pulverized Astragalus Root according to Method 4, and perform the test (not more than 5 ppm).
(4) Total BHC's and total DDT's. Not more than 0.2 ppm, respectively.
Loss on drying:
Not more than 13.0z (6 hours).
Total ash:
Not more than 5.0z.
Acid-insoluble ash:
Not more than 1.0z.
Containers and storage:
Containers.Well-closed containers.
