Two new coumarins from Zanthoxylum dimorphophyllum spinifolium and their feeding deterrent activities against Tribolium castaneum

Abstract

Zanthoxylum species and volatile oils have shown to have insect resistance. The present work was conducted to find alternative botanical source with significant activity on storage pests control. Chemical examination of Zanthoxylum dimorphophyllum Hemsl. var. spinifolium Rehder et E. H. Wilson stem bark has led to fifteen coumarins, which including two were novel compounds named 6-(2′,3′-dihydroxy-3′-methylbutyl)-7-hydroxyl-8-(3″-methyl-2″-butenyl)-2H-1-benzopyran-2-one (7) and 6-(2′-hydroxyl-3′-methyl-3′-butenyl)-7-methoxyl-8-(3″-methyl-2″-butenyl)-2H-1-benzopyran-2-one (8). All the chemical structures were elucidated on the basis of nuclear magnetic resonance spectroscopy and high resolution electrospray ionization mass spectrometry analysis. Additionally, dose-dependent feeding deterrent activities of fifteen coumarins against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) were evaluated scientifically. Among them, compound 12 (phellopterin) exhibited stronger feeding deterrent activity (EC50 = 64.00 ppm) than the positive control, toosendanin. While, compound 11 (imperatorin) displayed the same level of feeding deterrent activity as the positive control with median effect concentration of 73.10 ppm. The relationship between chemical structure and effectiveness showed that compounds with epoxy structure or isopentenyl group exhibited higher feeding deterrent activities and might have potential to be developed into novel feeding deterrent reagents or potential lead compounds on storage insect prevention and control.