ABSTRACT
Objective To compare the contents of astragaloside Ⅳ and polysaccharides in radix astragali with different growth years, providing reference for the better harvest time of radix astragali. Methods HPLC-ELSD was used to determine the content of astragaloside Ⅳ. A Hypersil-Keystone C18 column was used with the mobile phase consisting of acetonitrile-water (33∶67). The flow rate was set at 1.0 mL/min. The parameters of drift tube and gas flow rate of the detector were set at 105 ℃ and 2.7 L/min respectively. Phenol-sulfuric method was employed to determine the content of polysaccharides, and the detection wavelength was set at 490 nm. Results The linear range of astragaloside Ⅳ was within 1.25-6.28 μg. The average recovery was 97.28%, with RSD=1.42%. The linear range of polysaccharides was 10-100 μg. The average recovery was 99.02%, with RSD=0.94%. The content of astragaloside Ⅳ in radix astragali cultivated for more than 1 year was higher than the standard in Chinese Pharmacopoeia, and radix astragali cultivated for 3 years showed the highest content. The content of polysaccharides in radix astragali cultivated for more than 3 years was the highest, and radix astragali cultivated for 2 years was slightly lower. Conclusion The better harvest time for radix astragali is at least two years of growth, which is judged from the content of astragaloside Ⅳ and polysaccharides.