Studies On The Relationships Between The Selective Toxicity Of Celangulin V And Two Kinds Of Detoxifying Enzymes Of Insect

Celangulin V isolated from the root bark of Chinese bittersweet (Celastrus angulatus Maxim.) is a new insecticidal compound, and has selective toxicity against different insects.Cytochrome P450 and glutathione S -transferase are two kinds of important detoxifying enzymes related to the resistance of insect. The tolerance of insect to xenobiotics compounds could be increased by these enzymes after ruduced. By CO-differential spectral and SDS-PAGE, the cytochrome P450 content, NADPH-cytochrome P450 reductase activity and glutathione S-transeferase activity of the normal and the treated Mythimna separata and Agrotis ypsilon larvae were assayed, and compared the variety of the content and activity of these two kinds of detoxifying enzymes in larvae of M. separata and A. ypsilon, the results are as follows:In 2-day-old sixth instar of M. separata larvae, Celangulin V had higher induction against the cytochrome P450, and also could distinctively increased the cytochrome P450 content and NADPH-cytochrome P450 reductase activity, but had a little effect against the glutathione S-transferase.In the larvae of A. ypsilon, Celangulin V had lower induction against the cytochrome P450, there is a slight increase in the content of cytochrome P450 and the activity of NADPH-cytochrome P450 reductase, but it could distinctively increased the activity of glutathione S-transferase. Compared with the normal group, the glutathione S -transeferase activity of the treated groups increased 1.70 fold.In 5-day-old sixth instar of M. separata larvae, the cytochrome P450 content and glutathione S-transferase activity in the midgut and fat body played a main role against the metabolism of celangulin V, but NADPH-cytochrome P450 reductase activity and glutathione S -transeferase activity had no distinctively metabolism to celangulin V.In the larvae of A. ypsilon, the content of cytochrome P450 and the activity of glutathione S-transferase in the treated groups were apparently higher than the M. separata larvae, and the difference of cytochrome P450 content and glutathione S-transferase activity probably was a main mechanism of the selective toxicity of celangulin V in the larvae of M. separata and A. ypsilon.