1Departamento de Química, Centro de Ciências Exatas e Naturais, Universidade Federal do Pará, Campus Universitário, 66075-970 Belém-PA, Brazil.
2Laboratório de Agroindústria, Embrapa Amazônia Oriental, Trav. Dr. Enéas Pinheiro, S/N, 66095-100 Belém-PA, Brazil.
*Corresponding author: E-mail: mspa@ufpa.br
Two pyranoisoflavones, alpinumisoflavone and 4’-methyl-alpinumisoflavone and methyl 2-(β-D-glucopyranosyloxy) benzoate were isolated from the aerial parts of Pueraria phaseoloides. Phytotoxic effects of these compounds and of the P. phaseoloides hydroalcoholic extract fractions obtained by liquid-liquid partition were examined in Petri dish bioassay. The dichloromethanic and ethyl acetate fractions had a significant effect on seed germination of the weed species Mimosa pudica, showing 100 and 76% inhibition, respectively. However, the three isolated compounds had a greater effect on radicle elongation of the weed species Mimosa pudica, Senna obtusifolia, Senna occidentalis and Urena lobata. 4’-Methyl-alpinumisoflavone at the highest dose tested (3.0 ppm) exhibited stronger inhibition (77%) on S. obtusifolia, whereas, alpinumisoflavone at 3.0 ppm was more active (60% inhibition) on U. lobata and methyl 2-(β-D-glucopyranosyloxy) benzoate at 4.0 ppm (the highest dose tested) showed significant inhibition (44%) on M. pudica. Our experimental data showed that three natural products tested have selective herbicidal activity against weed species.
Allelochemicals, allelopathy, leguminosae, Mimosa pudica, Pueraria, phaseoloides, pyranoisoflavones, salicylic acid derivative, Senna, obtusifolia, Senna occidentalis, Urena lobata
