Allelopathy Journal

Some allelochemicals, viz., alkaloids and terpenoids, can fluoresce by excitation from ultra-violet or violet light. The fluorescence occurred both in intact secretory plant cells rich in alkaloids and terpenoids and in excretions from the cells of various organs of Achillea millefolium L., Berberis vulgaris L., Chelidonium majus L., Gaillardia pulchella Foug., Abies sibirica L., Ruta graveolens L.; Mentha piperita L., Lycopersicon esculentum Mill. Among the allelopatically active species studied, bright orange light emission was peculiar to root idioblasts of Ruta graveolens, which contain acridone alkaloids, especially rutacridone and to laticifers of Chelidonium majus, including alkaloids sanguinarine and chelerythrine, where blue fluorescence was seen due to sesquiterpene lactones located in secretory cells of leaves and flowers of genera Achillea, Artemisia and Gaillardia. The fluorescence may serve as a marker for the cytodiagnostics of the secretory structures in luminescent microscope. In our experiments, alkaloids viz., berberine, glaucine, casuarine fluoresced in violet-blue (410–470 nm) and green-yellow region with maximum 520 nm; the alkaloids rutacridone, sanguinarine, chelerythrine in orange spectral region (585–600 nm) and sesquiterpene lactones viz., artemisinine, tauremisine, gaillardine in violet-blue (410470 nm). When the pure fluorescent substances (10⁻⁶-10⁻⁵M) were added to the acceptor cell (vegetative microspores of Equisetum arvense or pollen of Hippeastrum hybridum) that served for the modelling of allelopathic interactions, the changes in their fluorescence were seen. Alkaloids, which also have the anticholinesterase activity, such as berberine and sanguinarine concentrated and fluoresced with yellow-orange colour on the surface of the cell. Pollen germination in artificial nutrient medium decreased after the addition of berberine and sanguinarine. As for alkaloid rutacridone and sesquiterpene lactones (artemisinine, azulene and gaillardine) which passed through plasmalemma into the cell, they stained intracellular structures. As a result, nuclei and chloroplasts became green-lightening (the staining with rutacridone) or blue-lightening (the staining with sesquiterpene lactones). The compounds may be used to study the mechanisms of allelochemical action and in laboratory practice as fluorescent dyes and probes.