Effects Of Tutin And Andrographolide Derivatives On Protective Enzymes And Gaba Metabolic Enzymes In Pseudalatia Separata

Tutin has neurotoxicity, stomach toxicity and antifeeding activity on many insects. The insecticide activity of tutin was closely related to its structure and functional groups, and it could be improved by structure modification. The leaf-disk methord was used for the determination of antifeedant activities of Tutin and the nine andrographolide derivatives (A2, A3a, A3b, A4a, A4b, A4c, A4d, A4e, A5), and there were four andrographolide derivatives (A2, A4b, A4d, A4e) with the higher antifeedant activities chosed for the determination of their effects on the protective enzymes activities (POD, CAT, SOD) and GABA relative enzymes (GAD, GABA-T) activities of Pseudalatia separata.1. The results of antifeeding activites determination showed that The antifeeding rate were 29.77%, 51.19%, 43.74%, 38.43%, 34.22%, 45.41%, 32.56%, 53.03%, 52.35%, 42.58% separately. The antifeeding activites of A2, A4b, A4d, A4e were higher.2. The results of the three protective enzymes activities determination indicated that the compounds tutin, A2, A4b, A4d and A4e inhibited the activities of POD and CAT but promoted the SOD activity in the tested larvae. Whereas the inhibition effect of A4b on CAT was slight, and the stimulation effect of A4e on SOD was indistinctive. Thus, tutin, A2, A4b, A4d and A4e inhibited the effects of detoxifcation metabolism on oxygen free radicals and H₂O₂ by interfering with POD, CAT and SOD activities in the tested larvae. A2 and A4d are the optimal compounds to inhibit POD, CAT activities and promoted the SOD activity, compared with the other two andrographolide derivatives and tutin.3. The results of the GABA relative enzymes activities determination showed Tutin and four andrographolide derivatives promoted GABA-T activity and inhibited GAD activity, and the effects of four andrographolide derivatives on GAD were higher than that of tutin. The inhibited GAD activity and promoted GABA-T activity in test insects by tutin and four andrographolide derivatives, accounted for reducedγ-aminobutyric acid (GABA) activity, disorder in nerve conduction and intoxication of test insects.4. The in vivo and in vitro determination methods showed that Tutin, A2, A4b, A4d, A4e have the similar effects on protective enzymes activity. In vitro method has provided preliminary basis for the fast determination of novel compounds toxicity effects on insects. 5. To synthesize the effects of each compounds on Pseudalatia separate, A2 and A4b were the best compounds in this paper.