Synthesis and biological activities of novel methyl xanthine derivatives

Caffeine is one of methyl xanthine compounds, which has the similar mode of action as ryanodine receptor insecticide. In order to find novel and efficient insecticide, structural modification of certain methyl xanthine compounds was made by introducing some common pesticidal active moieties into the structure of caffeine. Eleven novel methyl xanthine compounds were synthesized and characterized by 1H nuclear magnetic resonance(1H NMR), elemental analylsis or high-resolution mass spectrometry(HRMS). According to the biological activity results, it was found that these new compounds show moderate activity towards Mythimna separata Walker and Culex pipiens pallens. For example, compound 2d shows a lethality rate of 40% at 200 mg/L towards Mythimna separata Walker, compounds 2i and 2f show 56.7% and 53.3% lethality rates at 2 mg/L towards Culex pipiens pallens, which are all better than caffeine. In addition, some compounds of them show moderate antifungal activity to some plant pathogenous fungi.