Structural modification, fungicidal and insecticidal activity of 5-arylbenzofuran neolignan from Magnolia officinalis

Abstract As shown in a number of previous researches, the extracts of Magnolia officinalis exhibited broad-spectrum fungicidal and insecticidal activity. In our preliminary study, 5-arylbenzofuran neolignans, the secondary metabolite of Magnolia officinalis, was found to inherit the activity of Magnolia officinalis. For developing novel agrochemicals, natural 5-arylbenzofuran neolignan was selected as lead compound. After structural optimization, the fungicidal and insecticidal activity and selectivity were significantly improved. Compounds 5a, 5b, 6c and 6d displayed similar or equivalent activity compared with the positive controls against corresponding fungi or pests. Especially, compounds 6c and 6d exhibited the most promising insecticidal ability against Aphis fabae with the LC50 values of 3.56 mg/L and 5.96 mg/L, respectively. The preliminary structure-activity relationship was obtained, and the promising derivatives showed low toxicity in the model of human cells. The results of research indicated great potential of 5-arylbenzofuran neolignan derivatives in the field of fungicide and insecticide.