Phytochemical investigation and phytotoxic activity of aerial parts of oilseed radish (Raphanus sativus var. oleifer Stokes)

Raphanus sativus var. oleifer Stokes, commonly known as "oilseed radish", is used as a green fertilizer, and its straw has been used for soil coverage and nutrient recycling. Phytochemical investigation of oilseed radish aerial parts yielded seven compounds were identified from this taxon, three phytosterols (beta-sitosterol, stigmasterol and daucosterol), a norisoprenoid (S-(+)dehydrovomifoliol), two flavonoids (kaempferol 3,7-di-O-alpha-L-rhamnopyranoside and quercetin 3,7-di-O-alpha-t-rhamnopyranoside) and a phenylpropanoid (ferulic acid). With exception of sitosterol, the compounds isolated in this work are being described for the first time in this variety of Raphanus. The phytotoxic effects of the crude methanol extract and fractions of oilseed radish were evaluated on germination and initial seedling growth of Euphorbia heterophylla L. Bidens pilosa L. and Ipomoea grandifolia (Dammer) O' Donell, which are weed species commonly found in Brazilian agriculture. The dichloromethane fraction was the most active among those assayed and Bidens pilosa was the most sensitive weed.