Plants in medicine: lessons from the past and future perspective

Documenting historical knowledge about the use of medicinal plants can potentially lead to discovery of new ideas for practical applications of these plants. We collected and analyzed knowledge about the use of plant species found in the records of Latvian folk medicine. In addition, we aimed to evaluate the potential for the domestication of nine species of medicinal and aromatic plants (MAPs) with a high market potential distributed in natural habitats in Latvia: Primula veris, Galium odoratum, Daphne mezereum, Tussilago farfara, Pulsatilla pratensis, Convallaria majalis, Glechoma hederacea, Alchemilla spp. and Chaledonium majus.
Data on plants and their uses were collected from the records of Latvian folk medicine, the Archives of Latvian Folklore. Phytochemical analysis of aqueous ethanol extracts of selected plants was performed using liquid chromatography-mass spectrometry techniques to compare the chemical composition between populations growing in the wild and under controlled conditions. The impact of differences on the biological activity of plant material was evaluated using different in vitro and ex vivo methods.
The folklore materials analysed included information on 211 plant taxa, most of which were used for the treatment of disorders of the digestive and respiratory system. Only one quarter of the plant taxa mentioned in the studied records of Latvian folk medicine were included in the official monographs of the European Medicines Agency, and most of the plant indications mentioned in the records have not been described in evidence-based monographs. Changes in the chemical composition of selected MAP species between populations growing in wild and under controlled conditions were observed. For example, the total content of alkaloids in extracts prepared from cultivated Chelidonium majus was significantly higher than that of wild samples. Coptisine was the dominant compound in wild-grown C. majus extracts, however, chelidonine was found to be the dominant alkaloid after cultivation. Therefore, C. majus extracts prepared from cultivated specimens showed higher cytotoxicity in cancer cells than extracts from wild-grown plants.
Extracts of the selected MAPs are rich in bioactive components. Chemical analysis revealed significant differences in the qualitative and quantitative composition between wild and cultivated plants and confirmed the potential commercial use of selected MAPs in medicine, cosmetics, and food applications.

Acknowledgements: This work was supported by the European Regional Development Fund project “Innovative solutions for growing technologies and applications of spring medicinal and aromatic plants” (Nr. 1.1.1.1/18/A/043).