In Silico Evaluation of Synthetic Hydrophobic Fluorescent NBD- and DANSYL-Derivatives as Potential Inhibitors of Insect Chitinases

Insect chitinases are hydrolytic enzymes which are necessary for normal cuticle processing during insect molting – an essential step of insects’ developments. Surprisingly, some chitinases have hydrophobic amino acids residues close to active sites. Thus, here we report about virtual screening results which has involved 30 PDB chitinase structures and some original hydrophobic fluorescent compounds with 7-nitrobenzoxadiazol (NBD) and dansyl scaffolds, which have been synthesized in our group. Docking calculations in semi-automatic virtual screening mode have been done using AutoDock Vina (5x5x5 nm grid box, centered on the chain A ) and FYTdock helper software. N-hexanoyl ciprofloxacin has been found to bind with chitinases from Ostrinia furnacalis (pdb : 7vrg, 6jaw, 6jay, 6jmn, 5y2b; energy of bindings (Ebind) -10.2…-9.7). A visavi of the structure, N-hexanoyl-N’-NBD-piperazine, NpipHex, bind in silico with the enzyme less effectively (pdb codes: 6jaw, 5y2b, 6jay, 5y2c, 3wkz; Ebind -9.3…-8.9), and an open-ring analogue of NpipHex - N-hexanoyl-N’-NBD-ethylenediamine, has demonstrated similar affinity (pdb: 5gpr, 6jmn, 7vrg, 5gqb, 5y2c; Ebind -9.0…-8.7). In the same conditions N-NBD-oleylamine demonstrated less affine binding affinity (pdb: 6jmnc, 6jm8, 5gqb, 7vrg, 6jmb; Ebind -8.6…-8.0), and its counterpart, N-Dansyl-oleylamine , demonstrates better results (pdb: 5gpr, 6jav, 5jqb, 3wl0, 7wrg; Ebind -8.7…-8.3).

These results provide new insights into insect biochemistry of chitinases showing new molecular scaffolds suitable as prototypes as either pest control compounds or molecular tools for their fluorescence-based screening.

This study was supported by GSPSR (Belarus) № 20210560 and the grant from the Ministry of Education (Belarus) No. 20250893.