Preliminary Study Of Trypsin For Metabolism Of Deltamethrin

Chemical control is the main strategy of control vector-borne diseases.Because of the extensive application of pesticides, development of resistance has been reported worldwide. Indeed, the continuous development of resistance threatens the long-term viability of insecticide-based products.Detoxification ability of insects to insecticides is one of the main mechanisms of insecticide resistance.In our previous study, a serine protease gene named trypsin has been isolated through a combination of suppression subtractive hybridization (SSH) and microarray technology, Trypsin gene was significantly up-regulated in the deltamethrin-resistant strain of Culex pipiens pallens. Stable transfection of trypsin gene into mosquito C6/36 cells conferred protection against deltamethrin treatment, suggesting trypsin is related to insecticide resistance in Culex mosquito. In order to further explore the role of mechanism of Trypsin for Metabolism of Deltamethrin, deltamethrin degradation was assessed by measuring deltamethrin disappearance with UV-vis and GC-MS spectrophotometry .The toxicity of degradation products was detected by Up and Down method.The results showed that the UV–vis spectrophotometric peak absorbance of deltamethrin was at 264 nm, and the peak absorbance of deltamethrin metabolic products were at 250 nm and 296 nm respectively. The retention time of crude products of deltamethrin metabolic reactions (including undegraded substrate deltamethrin) were 37.968 min, 15.289 min, and 18.730 min. The peak that appeared in 37.968 min was undegraded deltamethrin, and the other peaks represented degradation products of deltamethrin catalyzed by trypsin,namely Cyclopropanecarboxylic acid (C9H12Br2O2, CAS number 72345-91-6) and 3-Phenoxybenzaldehyde (C13H10O2, CAS number 39515-51- 0) respectively. The acute oral toxicity of the metabolic to Wistar rats was 24.836 times lower than that of deltamethrin(p<0.05).Our work showed that trypsin could directly degrade small, non-protein molecules such as deltamethrin. And compared with deltamethrin, the toxicity of the degradation products reduced significantly. The results also suggest that trypsin might be an attractive candidate for the control of residual insecticides in the environment and on agricultural products.