[Sulfated modification conditions optimization of astragalus polysaccharide by orthogonal test and anti-IBDV activity determination of the modifiers].

Objective: To optimize the sulfated modification conditions of astragalus polysaccharide (APS) and probe into the probability of sulfated modification to enhance APS activity.

Methods: Total APS extracted by one-step ethanol precipitation and three fractional APSs extracted by stepwise ethanol precipitation method and purified were modified by chlorosulfonic acid-pyridine method. The modification conditions were optimized by L9 (3(4)) orthogonal design taking the ratio of chlorosulfonic acid to pyridine, reaction temperature and time. The degree of substitution (DS) was tested by sulfate barium turbidimetric method. The anti-IBDV activity of modification production was tested by MTT method.

Results: The optimized modification conditions were 1 : 6 of chlorosulfonic acid to pyridine, reaction temperature of 95 degrees C and reaction time of 1 hour.

Conclusion: Sulfated modification can enhance the antiviral activity of APS, which related to DS.