Scientific Publications by FDA Staff

Allelopathy J 2013 Apr;31(2):319-331

Phytotoxicity of Passiflora incarnata extracts on germination and growth of Hordeum vulgare and Raphanus sativus.

Keasling AW, Otter RR, Bailey FC

Phytotoxic chemicals are of interest because they represent potentially novel pharmacophores possessing herbicidal activity that may target new molecular receptor sites. This study aimed to evaluate the phytotoxic activity of Passiflora incarnata extracts against the monocotyledonous and dicotyledonous indicator test species barley and radish. Continuous exposure to total aqueous extracts of P. incarnata inhibited the barley germination at the lowest tested concentration (1.25% w/v), whereas 10% w/v concentration was required for radish. Aqueous fractions from sequential-solvent partitioning showed reduced seed germination inhibitory activity in both test species relative to total aqueous extracts. A 14-day growth assay showed that 24 h pre-/post-germination exposure to total aqueous extracts had no effect on dry weights of either species. However, 47% leaf-bleaching was observed in the 24 h post-germination exposure in barley. GC-MS analysis of solvent extracts identified phytol and palmitic acid as the major components. LC-ESI-MS/MS analysis of aqueous fractions tentatively identified ten compounds: phenylalanine, leucine, and tryptophan, swertisin, vitexin, saponarin, isoschaftoside, orientin, lucenin-2, and eugenol.