Chemical Screening of <i>Urochloa humidicola</i>: Methods for Characterizing Secondary Metabolites and Allelopathic Activity on Forage Legumes

Abstract

The aim of this study was to identify the main classes of secondary metabolites present in the root and shoot crude extracts and fractions from the forage grass Urochloa humidicola (Rendle) Morrone & Zuloaga and to evaluate the allelopathic effect of these metabolites on forage legumes for intercropping. Phytochemical prospecting analyses, 1 H NMR and capillary electrophoresis were performed on extracts of U . humidicola . Allelopathic activity was evaluated in germination of Stylosanthes , Macrotyloma axillare and Lactuca sativa L. (standard) in the presence of crude extracts, isolated saponins, flavonoids and trans-cinnamic acid. The metabolite classes present in the extracts could be determined by the combined use of the tested analytical techniques, but their use alone was usually not sufficient to chemically characterize the species. Capillary electrophoresis was effective in detecting phenolic compounds. Macrotyloma axillare was tolerant to crude extracts of U . humidicola . Saponins and trans-cinnamic acid, but not the flavonoids, reduced germination of the target plants.