Dokument

Summary:
As human population of the Earth grows, so are the needs to provide enough food for the humans and cattle. Agriculture plays major role in everyday food supply. As with human parasites and pathogens there are various pests which affect the yield of agricultural products. Nematodes are parasitic microscopic worms which infest various crops via various mechanisms. Root-knot nematodes are considered among the most difficult ones to treat. They penetrate the roots, feed on nutrient supplies of the plant and eventually multiply there. There are several nematode control methods and actually none of the methods can be considered to be ideal, as they may have high costs or be highly hazardous to human and environmental health safety. One of the control methods is treatment with chemicals which can also be associated with human health and environmental safety concerns. Methyl bromide is one of multipurpose pesticides which was once widely used as a nematicide and banned in 2005 due to the mentioned concerns. Allium plants have been widely used in folk medicine since ancient times. As there are more than 750 species worldwide and majority of them are not researched for their nematicidal activity it was decided to investigate several species using their bulbs and flowers. Bulbs and flowers of Alliums collected from Central Asia, Middle East and from local collection in IPK-Gatersleben in Germany were extracted using ethyl acetate. Local culture of root-knot nematodes, Meloidogyne incognita, was maintained by infesting tomato (Solanum lycopersicum) plants. The extracts were subjected to nematicidal assay against a universal root-knot nematode, Meloidogyne incognita. The most promising nematicidal extracts were investigated for their phytotoxic and brine shrimp lethality activities. Four most nematicidal plant extracts were investigated for their compounds responsible for the nematicidal effect. Each extract was separated in fractions and fractions were tested for the nematicidal activity. Structures of compounds in bioactive fractions were elucidated by high resolution mass spectroscopy and NMR spectroscopy analysis with further comparison and confirmation of the data with the ones previously reported in literature. As a result, it was found that, in A. ampeloprasum allicin is the most nematicidal compound and in A. stipitatum, two compounds, 2- (methyldithio)pyridine-N-oxide and 2-[(methylthiomethyl)dithio]pyridine-N-oxide were responsible for the nematicidal activity.

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