Departamento de Química, Centro de Ciências Exatase Naturais, Universidade Federal do Pará, Campus Universitário, 66075970 Belém-PA, Brazil, (2005).
Allelopathy Journal 15: 211–220.
Two pyranoisoflavones, alpinumisoflavone and 4’-methyl-alpinumisoflavone and methyl 2-($$-D-glucopyranosyloxy) benzoate were isolated from the aerial parts of Pueraria phaseoloides. Phytotoxic effects of these compounds and of the P. phaseoloides hydroalcoholic extract fractions obtained by liquid-liquid partition were examined in Petri dish bioassay. The dichloromethanic and ethyl acetate fractions had a significant effect on seed germination of the weed species Mimosa pudica, showing 100 and 76% inhibition, respectively. However, the three isolated compounds had a greater effect on radicle elongation of the weed species Mimosa pudica, Senna obtusifolia, Senna occidentalis and Urena lobata. 4’-Methyl-alpinumisoflavone at the highest dose tested (3.0 ppm) exhibited stronger inhibition (77%) on S. obtusifolia, whereas, alpinumisoflavone at 3.0 ppm was more active (60% inhibition) on U. lobata and methyl 2-($$-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.
