Influences of artificial disturbance degrees on the contents of Glycyrrhizic acid and flavonoids in different parts of Glycyrrhiza uralensis

The external factors which influence the wild liquorice and the cultivated liquorice (Glycyrrhiza uralensis) in any habitat may be classified into two categories: natural factors and unartificial factors. For cultivated liquorice, some artificial factors such as soil deep tillage, irrigation or the other manipulations of field management should be made an appeal further. The contents of Glycyrrhizic acid and flavonoids were measured in different parts of Glycyrrhiza uralensis under different conditions of artificial disturbance by ultrasonic extraction, HPLC and spectrophotometry.The variable trends of the contents of Glycyrrhizic acid and flavonoids were studied in different habitats with different extent of artificial disturbance. The results showed that artificial disturbances are principal influencing factors on the content of Glycyrrhizic acid and flavonoids in different parts of liquorice. They obviously decrease the content of Glycyrrhizic acid in different parts of wild liquorice, even if light artificial disturbance (viz. once soil deep tillage) had been brought into effect. The accumulation of Glycyrrhizic acid in wild liquorice rhizomes (especially horizontal rhizomes which have main functions for substance transportation and accumulation) in the light disturbed habitat is lower than the in undisturbed habitat. The contents of Glycyrrhizic acid in different parts of heavy disturbed cultivated liquorice were also low. The research results showed that the accumulation velocity of flavonoids was higher than that of Glycyrrhizic acid, which indicated that soil disturbed factors acted on the production and accumulation of glycyrrhizic acid more than on flavonoids. The contents of flavonoids in different parts of undisturbed wild liquorice and light disturbed wild liquorice displayed descending trend from overground parts to underground parts, but that in the leaf and the coronal root of heavy disturbed cultivated liquorice were high. Based on these results, it can be deduced that the main producing parts of flavonoids are the leaves and the coronal roots. The content of flavonoids in terrestrial stem and stem of leaf which have any functions for substance transportation was low and presented major amplitude of fluctuation. At different soil depths, the content of glycyrrhizic acid in different liquorices taproot revealed obviously distinction but that of flavonoids was not obvious, which indicated that the artificial disturbance didn't act distinctly on the content variation of glycyrrhizic acid or flavonoids in different depths of liquorice taproot. The content of glycyrrhizic acid in undisturbed wild liquorice and light disturbed wild liquorce at soil depths from 1.0m to 2.0m was high, which should be the reason that wild liquorice has adapted to corresponding soil environments in which wild liquorice lives. For heavy disturbed cultivated liquorice, its taproot was not extend corresponding soil depths so that the content of glycyrrhizic acid in its taproot at the depth under 1.0m was high. In a word, the artificial disturbance which can improve any growing conditions of liquorice have negative effects on accumulation of glycyrrhizic acid and flavonoids of wild liquorice and cultivated liquorice. The appropriate stress environment can have profit to improve quality of medical plants.