Abstract
The ethyl acetate extract of Citharexylum spinosum L. flowers was very phytotoxic to germination and seedlings growth of three target plants: radish (Raphenus sativus L.), lettuce (lactuca sativa L.) and canary grass (Phalaris canariensis L.). To determine the allelochemicals in ethyl acetate extract of C. spinosum, successive purifications were fone by column chromatography, giving three pentacyclic triterpene acids [oleanolic acid, ursolic acid and corosolic acid]. The structures of the isolated compounds were established by spectroscopic analysis including H-1, C-13, 2D NMR, DCI-HRMS and ESI-HRMS. Isolates and maslinic acid, previously isolated from pomace olive, were tested for their allelopathic effects against these three target plant. Corosolic acid and maslinic acid were tested for the first time for their phytotoxic properties. We found that the tested compounds exhibited variable activity due to differences in structures. The canary grass seeds were most sensitive to these tested triterpenic acids, the germination was totally inhibited by corosolic acid and maslinic acid at 60 ppm concentration.