The lupeol content in Machaerium species by HPLC-APCI-MS/MS and the allelopathic action

The use of extracts from plants and/or allelopathic compounds from natural products can minimize the use of pesticides in agriculture. This is a chemical study of Machaerium eriocarpum branch extract and the evaluation of the allelopathic potential of Machaerium hirtum (Vell.) Stellfed and M. eriocarpum Benth (Fabaceae) leaves and branches extracts. The triterpene lupeol was isolated from the hydroethanolic extract of M. eriocarpum branches. The quantification of this compound in all extracts was performed by HPLC-APCI-MS/MS and the highest amount of lupeol was observed in the leaves extract of M. eriocarpum. Allelopathy tests were carried out against seeds of Sorghum bicolor L. (sorghum), evaluating the final percentage of germination, germination speed index (GSI), root growth and number of lateral roots. The leaves extracts of both species were effective in the inhibition of the root growth as well as of the lateral roots. The branches extract of M. hirtum showed inhibitory effect in the root growth and lateral roots only in 50 and 100 mg.L-1 doses. The lupeol showed mainly a strong inhibition of seed germination, root growth and lateral root appearance at 100 μM. This study showed the potentiality of Machaerium extracts and lupeol as bioherbicides. Key words: Allelopathy, lupeol, Machaerium, Fabaceae, Sorghum bicolor, phytoxicity