Contribution of phenolic acids and dimethyl sulfone to the allelopathic effect of invasive Tridax procumbens

ABSTRACT Tridax procumbens is an invasive weed with a strong allelopathic activity. In this study, the contribution of phenolic acids and dimethyl sulfone to the allelopathic effect of T. procumbens was evaluated against Raphanus sativus. Phenolic acids (benzoic, ellagic and ferulic), vanillin and dimethyl sulfone were identified and quantified from the strongest fraction of T. procumbens, in an allelopathic assay by high performance liquid chromatography and gas chromatography - mass spectrometry. The contribution of phenolic acids and dimethyl sulfone to the allelopathic effect of T. procumbens, expressed as a total activity, was evaluated by comparing the IC50 value to the concentration of each allelochemical, in a completely randomized design. The benzoic acid presented the strongest inhibitory effect (115 mg kg-1) and the highest contribution (0.483) to the allelopathic effect of T. procumbens, followed by vanillin, dimethyl sulfone and ferulic acid.