Chemical components from the stems and leaves of Clausena lansium (Lour.) Skeels and their potential herbicidal effects.

BACKGROUND: Clausena lansium (Lour.) Skeels, belonging to the genus Clausena of the family Rutaceae, has a wide range of medical and agricultural activities. Previous studies on agricultural activities have shown that C. lansium extracts and some components have obvious herbicidal activities. In order to study systematically herbicidal activity of this plant, we studied the herbicidal effect of ethyl acetate (EtOAc) extract from the stems and leaves of this plant and further isolated the active compounds. RESULTS: The EtOAc extract inhibited the growth of roots and shoots of Echinochloa crus‐galli (L.) Beauv., and the inhibitory effect of the EtOAc extract on roots were stronger than those on shoots with half maximal inhibitory concentration (IC50) values of 420.45 and 585.05 mg L−1, respectively. Fifteen compounds were subsequently isolated and identified from the stems and leaves of C. lansium, including nine O‐monoterpenoid furanocoumarins and six cinnamamides. Our results showed that most compounds exhibited varying degrees of herbicidal activities to E. crus‐galli. Among them, compounds 3, 8, and 13–15 showed the best inhibitory activities on the growth of E. crus‐galli roots, with inhibition rate values ranging from 70% to 83% at a concentration of 300 mg L−1. Compounds 1 and 2 are two new compounds, and their structures were established as 5‐O‐monoterpenoid furanocoumarin and 8‐O‐monoterpenoid furanocoumarin, and named as claulansicoumarin‐A and ‐B, respectively. CONCLUSION: The EtOAc extract and pure compounds showed noticeable herbicidal activities against E. crus‐galli and indicated a great potential for these natural compounds to be developed as a herbicide. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]