Summary

The aim of the project ToxPot was to evaluate the potential of potato-side streams for further utilization, focussing on the extraction and applicability of secondary metabolites like the well-known potato glycoalkaloids α-solanine and α-chaconine. The above-ground plant material consisting of berries, leaves, stems, and also flowers remains as unused residual biomass after potato production in the field. However, it is known that these plant parts contain high amounts of the glycoalkaloids α-solanine and α-chaconine. Our results confirm the high amounts of these glycoalkaloids in flowers and berries. Furthermore, differences in glycoalkaloid concentrations were detected between cultivars, tissues, and developmental stages. Although flowers of different cultivars show a significantly higher amount of these glycoalkaloids compared to potato berries, an extraction from young berries, which show higher glycoalkaloid concentrations than old berries, seems preferable due to their higher biomass compared to flowers. Two conducted field trials show, that harvesting berries and flowers during potato cultivation does not affect the final tuber yield. Besides the main potato glycoalkaloids, metabolite profiling revealed the presence of phenolic compounds, which show potential biological activities interesting for e.g. pharmaceutical industry, in potato flowers and berries. Through the establishment of a HPLC-MS/MS method we were able to validate and quantify the concentration of the two interesting compounds Hovetrichoside C and Kaempferol-3-O-galactoside, which have not been described in potato before, in aboveground plant parts of different potato cultivars. In addition to the identification and quantification of compounds present in above-ground potato parts, we aimed at the generation of potato glycoalkaloid derivatives with potentially new biocidal or bioactive properties. The aglycon solanidine was chosen as substrate for the generation of derivatives. Solanidine was obtained via acidic hydrolysis of extracted and purified α-solanine and α-chaconine. Due to the low yield of solanidine, cholesterol, which shares similar scaffolds as solanine and chaconine, was chosen as a substrate for optimization of the synthesis of solanidine derivatives. In order to evaluate the bioactivity and potential applicability of compounds derived from potato plant residuals as well as their derivatives, in vitro tests were conducted on non-target (plants, beneficial microorganisms) and target organisms (phytopathogenic bacteria, fungi, and nematodes). The results are promising and show, that particularly the growth of fungal phytopathogens was impaired by the potato glycoalkaloids with α-chaconine showing a stronger effect than α-solanine also at low concentrations. Although further testing of potato compounds in vivo is necessary, our results confirm the potential applicability of potato glycoalkaloids for the utilization in plant-based phytopathogen control.