Seasonal variation of the essential oil, valerenic acid and derivatives, and velopotriates in Valeriana officinalis roots and rhizomes, and the selection of plants suitable for phytomedicines.

During the seasons 1989-1993, Valeriana officinalis plants were investigated for their contents of essential oil, valerenic acid and derivatives, and valepotriates. Harvesting of the subterranean parts was started in August of the year in which the seeds were sown, and continued until the last week of April of the subsequent year. Despite marked variations from year to year, the maximum contents of essential oil in the subterranean parts of V. officinalis were found in September, ranging from 1.2% to 2.1% (v/w) based on dry weight (DW). Over the vegetation periods investigated, the composition of the oil remained more or less constant. Valerenic acid and its derivatives, and the valepotriates reached their maxima in February-March, with contents of 0.7-0.9% (DW) and 1.1-1.4% (DW), respectively. During the period 1989 - 1993, five V. officinalis strains were investigated for their contents of essential oil, valerenic acid and derivatives, and valepotriates in order to select plants suitable for phytomedicines. The selection procedures described in this paper finally yielded plant material (in 1993) with a satisfactory content of essential oil (0.9%) combined with a high content of valerenic acid and derivatives (0.5%) which can be harvested in September of the year of sowing.