›› 2011, Vol. 54 ›› Issue (12): 1368-1376.

• RESEARCH PAPERS • Previous Articles     Next Articles

Isolation and identification of insecticidal compounds from Tephrosia purpurea (Fabaceae) bark and their insecticidal activity

 LI  You-Zhi, LI  Guan-Hua, WEI  Xiao-Yi, LIU  Zhong-Hua, XU  Han-Hong   

  1. National Research Center of Engineering & Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha 410128, China
  • Received:2011-07-04 Revised:2011-11-17 Online:2011-12-20 Published:2011-12-20
  • Contact: XU Han-Hong E-mail:hhxu@scau.edu.cn
  • About author:liyouzhi2008@sina.com

Abstract: In order to determine insecticidal compounds from the methanol extracts of Tephrosia purpurea bark, the active compounds were isolated by activity-guided fractionation with column chromatography and identified based on NMR (nuclear magnetic resonance) and MS (mass spectrometry) data. Slide-dip method was performed to determine the insecticidal activities of each compound against Myzus persicae adults, and topical application was conducted to determine contact toxicity of each compound against the 3rd instar larvae of Pluttella xylostella. Ten known compounds were isolated and identified, i.e., 12a-hydroxyrotenone, 4′-hydroxyemoroidocarpan, pachyrrhizine, rotenone, 6-methoxycoumarin, (-)-edunol, obovatin, pongachin, 12-acetyelliptinol and 2-hydroxyrotenone. All these compounds exhibited insecticidal activity against the 4th instar larvae of Aedes albopictus with the LC50 value being 12.5, 22.1, 25.0, 34.1, 43.4, 58.4, 121.9, 191.0, 219.8 and 250.0 mg/L, respectively at 24 h after treatment. Moreover, three compounds (4′-hydroxyemoroidocarpan, rotenone and 12a-hydroxyrotenone) exhibited insecticidal activity against M. persicae adults and the 3rd instar larvae of P. xylostella with their corresponding LC50 values being 49.9, 1.9 and 0.9 mg/L against M. persicae adults, and with the LD50 values being 49.8, 197.1 and 40.9 μg/individual against P. xylostella larvae, respectively. Eight known compounds, i.e., 4′-hydroxyemoroidocarpan, 2-hydroxyrotenone, 6-methoxycoumarin, pachyrrhizine, (-)-edunol, 12-acetyelliptinol, pongachin and obovatin, were isolated from T. purpurea bark for the first time. The elucidation of the structure of these phytochemicals and their insecticidal activity is important not only for understanding the insect-plant relationships, but also for assessing the potential of this plant as botanical insecticide to be explored and utilized.

Key words: Tephrosia purpurea, insecticidal compounds, insecticidal activities; Aedes albopictus, Pluttella xylostella, Myzus persicae