Isolation and identification of 2-isopropyl-5-methylphenol fromStellera chamaejasmeand its insecticidal activity againstAphis craccivoraandPieris rapae

In this study, the root powder of Stellera chamaejasme was extracted with chloroform. The crude extract thus obtained was chromatographed several times with silica gel columns and finally one pure natural product was obtained. This product was identified as 2-isopropyl-5-methylphenol (thymol), which was separated for the first time from S. chamaejasme root. The results of a laboratorial bioassay showed that it had good insecticidal activity against Aphis craccivora and Pieris rapae. Its median lethal concentrations (LC50) (24 h after treatment) were 14.81 and 47.68 mg L(-1), respectively. This is the first time that the insecticidal activity of thymol against A. craccivora and P. rapae has been reported.