Insecticidal activity of Sikimi extract and its modulation of the GABA A receptor channel

✍ Scribed by Ikeda, Tomoko; Nagata, Keiichi; Honda, Hiroshi; Shono, Toshio; Narahashi, Toshio

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 260 KB
• Volume: 52
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(199804)52:4<337::aid-ps738>3.0.co;2-8

✦ Synopsis

Sikimi plant (also known as Japanese star anise), Illicium anisatium, is toxic to mammals. Extracts of Sikimi were studied for their insecticidal activity against the larvae of mosquito, Culex quinquefasciatus, and for their mechanism of action on ion channels. Crude methanol extract and its ethyl acetate-soluble fractions were insecticidally active, with values of 63É0 kg ml~1 and EC 50 43É7 kg ml~1, respectively. The ethyl acetate-soluble fraction was perfused through the bathing solution and the current induced by a brief (10 ms) application of GABA by pressure ejection through pipette electrode was recorded by the whole-cell patch clamp technique. The extract suppressed GABA-induced currents irreversibly with an value of 0É42 kg ml~1. The time constant of EC 50 current Ðtted to the single exponential function was shortened by the ethyl acetate-soluble fraction at concentrations ranging from 0É1 kg ml~1 to 10 kg ml~1 in a concentration-dependent manner. It was concluded that Sikimi extracts decreased the affinity of GABA for its binding site on the GABA receptor, thereby suppressing GABA-induced currents.

1998 SCI (