Photostability of abamectin/zein microspheres

Abamectin, a natural product pesticide that degrades rapidly in air and sunlight, has been encapsulated with the protein zein. The result was a mineral oil suspension that included a photostabilized abamectin. After exposure to simulated sunlight, the microsphere suspension provided a several-fold increase in recoverable abamectin residue. The enhanced photostability of the microspheres is due to retarded reaction between oxygen and the diene chromophore of abamectin, in the presence of light. The zein could function as a quencher of singlet oxygen and/or a physical oxygen barrier.