common herbivore, H. armigera, which
has become resistant to traditional insecticides, feeds on more than 100
species of crops. The need is to look for more advanced insecticides with
greater efficacy to get desired result. For the development and survival of
cotton bollworm the SCP-2, a sterol carrier protein appears to be an absolutely
necessary gene. It is verified by Expression knockdown experiments of HaSCP-x/2
transcripts that it could delay both larval development and decrease fertility.
This study was conducted to investigate the interaction mechanism and to
illustrate the binding model for the active site of HaSCP-2 with its potential
inhibitors. Larval rearing was carried out under optimal rearing conditions. The
three-dimensional structure of SCP-2 for virtual screening was retrieved from
Protein Data Bank structure was preprocessed and converted into PDBQT file
format. For virtual screening study natural product library & Mybridge
library were used and a total of 218,780 compounds were selected for molecular
docking by AutoDock Vina program. Top 300 highest ranked compounds were selected
for further screening. On the basis of structural diversity and docking scores nine
compounds were selected as potential candidates for bioassay. Larvae were
treated with selected nine compounds with control group. Out of nine compounds
in vivo bioassays, only two compounds H1 and H14 showed inhibitory effect over
growth of Larvae. Doses of H1 or H14 given at the ontogeny stage caused
arrested larval development of H.armigera.
Thus it was suspected that the high levels of HaSCP-2 inhibitors could induce
the expression of detoxification enzymes, such as P450 or GST. The molecular docking
revealed that H1 and H14 were bound to helix a2 and the helix a5 of HaSCP-2 in
a similar fashion with hydrophobic interactions and van der Waals interactions.
Furthermore, the results indicated that H1 andH14 are vital useful lead
compounds for further optimization and designing of novel SCP-2 targeting
pesticides to overcome the H.armigera.