Objective:

2

To study on the content change and transformation rule of eight main characteristic components in stir-frying process of Glycyrrhizae Radix et Rhizoma.

Method:

2

The contents of liquiritin apioside

liquiritin

isoliquiritin apioside

isoliquiritin

liquiritigenin

isoliquiritigenin

glycyrrhizic acid and glycyrrhetinic acid in Glycyrrhizae Radix et Rhizoma were determined simultaneously by HPLC. The chromatographic conditions were Waters Symmetry® C

18

column (4.6 mm×250 mm

5 μm)

and the mobile phase of acetonitrile (A)-0.05%phosphoric acid solution (B) for gradient elution (0-9 min

19%-25%A; 9-18 min

25%-34%A; 18-38 min

34%-51%A; 38-58 min

51%-89%A)

the flow rate of 1 mL·min

-1

the detection wavelengths at 320 nm (0-16 min)

276 nm (16-25 min)

370 nm (25-28 min)

254 nm (28-58 min)

the injection volume of 10 μL and the column temperature at 30 ℃.

Result:

2

After stir-frying

the total content of three components with dihydroflavone as mother nucleus was decreased

while the total content of three components with chalcone as mother nucleus showed an upward trend

the content change of glycyrrhizic acid was not obvious

but glycyrrhetinic acid content showed a slight upward trend. When the monomer heating temperature reached 130 ℃

dihydroflavones and chalcones could be isomerized with each other

and with the increase of temperature

the isomerization became more obvious. When the heating temperature rose to 180 ℃ (isoliquiritin apioside was 130 ℃)

in addition to the isomerization

the glucosidic bond of flavonoid glycosides began to break and gradually transformed into the corresponding secondary glycosides or aglycones. Glucosidic bond of glycyrrhizic acid could also be broken to form glycyrrhetinic acid

which was detected at 150 ℃.

Conclusion:

2

The change of chemical composition is complex during stir-frying process of Glycyrrhizae Radix et Rhizoma

in addition to the isomerization and glucosidic bonds breaking observed in this experiment

there may be other complex reactions. The content of one compound in the herb is affected by many factors during its processing

such as the time and temperature of frying

the stability of the compound itself and so on.