Identification of allelochemicals in the essential oil of Euphorbia maculata L. and their bioactivity

We determined the chemical composition and allelopathic activity of the essential oil from Euphorbia maculata L. and to study the bioactivity of allelopathic constituents against Lolium perenne, Clitoria ternata, Portulaca oleracea and Amaranthus viridis. Results showed that 47 components were identified in the essential oil. Based on bioactivity-guided fractionation, the main active constituent was isolated and its structure was determined as diphenylamine (29.41%) by high-resolution electrospray ionization mass spectrometry and 1D nuclear magnetic resonance techniques. Both the essential oil and diphenylamine exhibited allelopathic activity. The essential oil at 0.2% (w/v) concentration inhibited the seed germination and seeding growth of Clitoria ternatea, Portulaca oleracea and Amaranthus viridis, but slightly stimulated the germination and growth of Lolium perenne weed. The bioactivity analysis of the isolated compound showed that diphenylamine and the oil at the same concentration significantly inhibited the seed germination and seedling growth of these four weeds. Thus essential oil from E. maculata inhibited the germination and growth of test weeds, hence, could be used for weeds control.