Contents of essential oil, valerenic acids and extractives in different parts of the rootstock of medicinal valerian (Valeriana officinalis L. s.l.)

•Adventitious roots contain higher ingredient contents as lateral roots.•Thicker valerian roots do not contain lower ingredient contents.•High levels of extractives contents are located in rhizomes.•A loss of lateral roots do not decrease the ingredient contents of the root drug.

In 2008, a breeding project was started with the aim to develop one or several varieties of Valeriana officinalis L. s.l. with a coarse root system and reliable ingredient contents according to the pharmacopoeia. It was initially assumed that a negative relationship between the adventitious root thickness and the ingredient contents exist.Therefore, the clones of four genotypes, differing in root fineness and ingredient content, were cultivated. The rootstocks were carefully harvested by hand in autumn and the rootstock components, rhizomes and roots, were separated. The roots were assigned to four diameter groups and the lateral roots were separated from the adventitious roots after drying. The analyses of the valerenic acids, essential oil and formerly listed extractives were conducted according to the current European Pharmacopoeia.In general for the investigated genotypes, the highest contents of valerenic acids and essential oil are located in the adventitious roots, followed by the lateral roots and the rhizomes. In contrast to the other ingredients, the extractives content of the rhizomes are comparatively high. Differences in the investigated ingredient contents and the different root thicknesses are not detectable.The investigation indicates how important careful harvesting and preparation of the rootstock are to conserve the existing ingredients. In addition, the different ingredient contents of the adventitious and lateral roots are not expected to decrease ingredient contents of the root drug when lateral roots and thin adventitious roots are lost during root cleaning and preparation. The study also shows that despite initial assumptions, thicker roots did not result in a decline of ingredient contents.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide