Pattern of allelochemical distribution in leaves and roots of tough lovegrass (Eragrostis plana Nees.).
This is the first report on chemical compounds in tough lovegrass, an allelopathic plant considered to be the most abundant invasive plant in the rangelands of Southern Brazil. This study aimed to evaluate the distribution and concentration of allelochemicals in the leaves and roots of tough lovegrass. Plant material was collected from anarea of secondary vegetation in April 2013. Aqueous extracts (leaves and roots) were prepared and subjected to turboextraction and subsequent lyophilization. The extracts were subjected to qualitative chemical tests in order to evaluate their alkaloids, anthraquinones, flavonoids, tannins, and saponins content. Post-validation high-performance liquid chromatography (HPLC) assay was used to evaluate the allelochemicals caffeic, ferulic, p-coumaric, vanillic acids, coumarin, catechin, epicatechin, rutin, quercetin, gallic acid, and kaempferol. Qualitative chemical tests detected the presence of saponins, alkaloids, and flavonoids in the leaves and roots of tough lovegrass and tannins in only leaves. HPLCassay verified the presence of coumarin in the roots and leaves in equal amounts; ferulic acid in higher quantities in roots; caffeic, p-coumaric, and vanillic acids in higher quantities in leaves; and catechin and epicatechin in leaves only. The compounds rutin, quercetin, gallic acid, and kaempferol were not detected in the extracts. The presence of secondary metabolites varied in different plant organs. Our results demonstrated greater amount of compounds in the leaves; therefore, this organ should be prioritized in the future with isolation of compounds. The presence of allelochemicals indicates that the compounds of this species can be potentially used as bioherbicides.