Two new insecticidal sesquiterpene esters from Euonymus japonicus

Area of Science:

• Natural Products Chemistry
• Insecticide Discovery
• Organic Chemistry

Background:

• Euonymus japonicus Thunb. is a plant species known for its diverse chemical constituents.
• Sesquiterpene esters are a class of natural products with potential biological activities.
• Insect pests like Mythimna separata cause significant agricultural damage.

Purpose of the Study:

• To isolate and characterize novel insecticidal compounds from Euonymus japonicus root bark.
• To evaluate the insecticidal potency of isolated compounds against Mythimna separata.

Main Methods:

• Bioassay-guided fractionation of EtOAc extract from Euonymus japonicus root bark.
• Structure elucidation using Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR) spectral data.
• Determination of LD50 values for isolated compounds against Mythimna separata.

Main Results:

• Two new insecticidal sesquiterpene esters, ejaponine A (1) and ejaponine B (2), were identified.
• Two known compounds, 3 and 4, were also isolated and characterized.
• Ejaponine A (1) exhibited an LD50 of 89.2 μg/g, ejaponine B (2) of 98.6 μg/g, compound 3 of 181.4 μg/g, and compound 4 of 109.2 μg/g against Mythimna separata.

Conclusions:

• Ejaponine A and ejaponine B are potent new insecticidal agents derived from natural sources.
• Euonymus japonicus root bark is a valuable source for discovering novel insecticides.
• The isolated compounds demonstrate potential for developing new pest control strategies.