Phytochemical and allelopathic studies of Terminalia catappa L. (Combretaceae)

The allelopathic potential of Terminalia catappa L. Combretaceae fruits and leaves on Lactuca sativa L. (lettuce), Euphorbia heterophylla L. and Commelina benghalensis L. was studied. Bioassays indicated the highest activity for dichloromethane and ethyl-acetate fractions of ethanolic extracts from fruits, and the mean effective concentration (EC50) was determined. 2-Pentadecanone; vanillic, siringic, ferulic, p-coumaric, palmitic and stearic acids were characterized in the dichloromethane fraction, and 3,4,4'-tri-O-methyl ellagic acid and beta-sitosterol-3-O-beta-D-glucoside were isolated from it. No allelopathic effects were observed when the dichloromethane extracts of T catappa fruit or leaf extracts were applied to the weeds E. heterophylla and C. benghalensis. Bioassays with seasonal sampling revealed an influence on the allelochemical potential of T catappa. Considering the methodology adopted and the experimental results, the allelopathic activity of T. catappa seems to be related to the interaction of different groups of substances, some of them identified and characterized in this work. (C) 2011 Elsevier Ltd. All rights reserved.