Active component isolated from Eugenia caryophyllata leaves and its structural analogues show insecticidal properties against Pochazia shantungensis

The purpose of this study was to isolate an active constituent from the essential oil of Eugenia caryophyllata leaves and to evaluate its insecticidal activity against the nymph and adults of Pochazia shantungensis. According to some chromatographic methods and spectroscopic analyses, the active constituent of E. caryophyllata leaves was identified as eugenol. Based on the $LC_{50}$ values of eugenol and its structural analogues against the nymph and adults of P. shantungensis, isoeugenol ($LC_{50}$, 83.29 and 91.03 mg/L) exhibited the highest insecticidal activity, followed by methyl isoeugenol (105.61 and 114.48 mg/L), eugenol (124.44 and 143.24 mg/L), methyl eugenol (126.31 and 143.84 mg/L), and acetyl eugenol (165.11 and 170.06 mg/L). Insecticidal activity against P. shantungensis was dependent on the presence of a functional group in 4-ally-2-methoxyphenol. In conclusion, E. caryophyllata oil and eugenol analogues might be suitable alternative synthetic insecticides.