Table 3.
The aldose reductase inhibition docking scoresa and type of binding interactions of the major components of the essential oil & the standard (Epalrestat).
| Comp | Binding energy (Kcal/mol)a (docking score) | Type of binding interactions |
|---|---|---|
| Epalrestat | − 11.0 | Two H-bonds with Lys21 |
| H-bond with Trp20 | ||
| Arene-cation interaction with Arg268 Strong hydrophobic interaction with Lys262, Pro215 and Asp216 | ||
| Ah major components | ||
| Caryophyllene | − 8.0 | Strong hydrophobic interaction with Arg268, Pro215 and Leu228 |
| Caryophyllene oxide | − 9.0 | H-bond with Lys262 |
| Strong hydrophobic interaction with Arg268 and Pro215 | ||
| ( +)- Sabinene | − 7.1 | Strong hydrophobic interaction with Arg268 and Lys262 |
| D-limonene | − 6.7 | Strong hydrophobic interaction with Arg268 and Lys262 |
| Alpha-Copaene | − 8.5 | Strong hydrophobic interaction with Arg268 and Lys262 |
| Beta-pinene | − 6.8 | Strong hydrophobic interaction with Arg268 and Lys262 |
| Trans-verbenol | − 7.9 | Two H-bonds with Arg268 and Ser263 |
| Strong hydrophobic interaction with Pro215 and Lys262 | ||
| Alpha-pinene oxide | − 7.7 | Two H-bonds with Arg268 and Ser263 |
| Strong hydrophobic interaction with Pro215, Asp216 and Lys262 | ||
Significant values are in bold.
Epalrestat was used as reference aldose reductase inhibitor compound.
Docking was carried out following the reported procedures26 against the aldose reductase enzyme pocket (PDB code ID: 3RX2).
aMore negative score refers to better capability of a molecule to dock with the target and make more desirable interactions.