Wenjun Wu
Institute of Pesticide Science, Northwest A&F University, Yangling, Shanxi 712100, China
Anglestem Bittersweet,Celastrus angulatus Max., is a traditional insecticidal plant widely distributed over the Yellow River and Yangtze River basins of China. The insecticidal compounds exist in the root bark and leaves. A total of 68 bioactive compounds have been isolated from the extracts of the root bark and leaves. All these compounds are belonged to sesquitepene polyolester and celangulin V is a main active compound of the plant.
In order to use the extracts of Celastrus angulatus Max. some work of basic research on the formulations，formulations preparation，application，evaluation on the safety of non-target organisms，and degradation dynamic of celangulin V were carried out.
In order to increase the activity and as a lead to screen the candidate compounds some work of structural modification of the active components were carried out and 66 derivative of celangulin V were designed and prepared.
In order to find the novel target of this insecticidal compound, the active component was used as a probe and symptomic observation showed that about 2 hours after ingesting some amount of celangulin V, the larvae felled convulsed slightly losing the body fluid (regurgitation juice and hemolymph) seriously felled death. The results of electron microscopy observation indicated that there are receptors of celangulin V in the midgut tissue of the insects. Several methods were employed to isolate the target protein (including: mRNM display; H3 radio labeled probe; fluorescent tag probe; biotin tag probe; affinity chromatography). Total 11 binding proteins were identified by MS after partial try ptic digestion and database search. V-ATPase subunit H was considered as the putative target protein of Celangulin V based on the symptom of poisoning insects and biological function of binding proteins. V-ATPase subunit H of M. Separata was validated to be the target of insecticidal celangulin V and its analogue based on the following:
(1) Celangulin V and its analogue could inhibit the activity of V-ATPase
(2) Celangulin V and its analogue could bind with the subunit of V-ATPase
(3) Deletion of the subunit H could lead to the death of the insects with the same symptom as the treatment by celangulin V.
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