Studies on Anatomy, Histochemistry and Accumulation of Saponins in Polygala Tenuifolia
|Keywords||Polygala tenuifolia Anatomy Histochemistry Tenuifolic senegenin xanthone|
Polygala tenuifolia Willd, which belongs to Polygalaceae and Polygala L., is a perennial herbage plant, used its drying root as medicines.The major medicinal components are Tenuifolic saponin and Xanthone After reviewing the previous studies on its distribution, morphorlogy, resource, chemical component, pharmacology, the technique of propagation and cultivation, we investigated the structures of Polygala tenuifolia’s root, stem and leaf, as well as their developments.. Meanwhile, the main medical composition of vegetative organs and storage nutrition of the root and seed were localized.The dynamic changes of senegenin contents were studied from different organs, periods and elicitors inducement, by using anatomy, histochemistry and phytochemistry methods. The results are shown as follow:1. The development and primary structure of root and stem of Polygala tenuifolia are the same as other dicotyledons. Root primary xylem is diarch, and its secondary growth mainly depends on the activity of the vascular cambium and cork cambium. The cork cambium originated from the pericyclic cells and created multi layer of phelloderm parenchyma cells. The development of stems could be divided into four stages: promeristem, primary meristem, primary structure and secondary growth .There is a layer fiber of big cells around the stem’s phloem, which originated from procambium. The leaf of Polygala tenuifolia is typical bifacial leaf.2. The main reserve substance is oils and there is a little polysaccharides in Polygala tenuifolia root. The reserve substance in seeds is mainly oils and some cells contain polysaccharides.The tenuifolic saponins exists in all the parenchyma cells and the cork cambium of root. In stem, it mainly exists in cortex cells, the other position contents less or none. At leaf, it mainly contents in epidermic cells and mesophyll cells. The phloem cells in vascular bundle also have a little. The root phelloderm parenchyma cells and secondary phloem are all have xanthones.3. The contents of senegenin in different organs, developmental stages and different years from Polygala tenuifolia were analyzed by HPLC. There exists great discrepancies of the contents of senegenin in each organ of Polygala tenuifolia. The highest content appeared in periderms and phloems. The content of senegenin in other organs is shown as follows: Leaf > seed> stem> flower > root xylem. The senegenin in periderms and phloems of Polygala tenuifolia increased from January to June, decreased rapidly in july, and then began to rise. It showed downwards trend after September. The content of senegenin in root xylem is similar to the existence in periderms and phloems. The highest content appeared in Auguest. Senegenin content in aerial part of Polygala tenuifolia’s general tendency is as follow: after increasing in leaf-expansion period, the figure reached its maximum in the end of May, then decreased until Auguest.