*2.6. In Silico Docking of Major Constituents against BCL-2 and CASPASE-3*

The computational interactions against ligands from the EO with BCL-2 and CASPASE-3 protein receptors were analyzed. In this study, the possible binding patterns and interaction mechanisms of major constituents—including α-pinene, camphene, β-pinene, β-myrcene, car-4-ene, α-terpinene, limonene, p-cymene, β-caryophyllene, α-humulene, β-farnesene, caryophyllene oxide, eucalyptol, linalool, nerol, and camphor—of the EO were analyzed using an auto-docking tool and evaluated using the binding energy and binding efficiency (Figure 6). In general, the binding intermol energy represents the best fit for a ligand in the active site of the target macromolecule. The in silico binding results revealed that, of the major constituents of EO, eucalyptol, linalool, nerol, and camphor showed the highest binding energies and high intermol energies (−3.76, −4.29, −3.37, and −5.5 kcal/mol, respectively). The docking simulation of BCL-2 to EO components resulted in the formation of eight hydrophobic interactions with potent binding energy, ligand efficiency, and intermol energy (Table 2). Several hydrophobic amino acid residues in chain-A and three predominant interactions with chain-B were observed in these EO interaction studies. Four major amino acid residues interacted with EO components in

chain-A: Met-163, Arg-161, Lue-136, and Lys-137. Meanwhile, in chain-B, the predominant binding was against His-117, Val- 266, and Thr-266. Interactions against pro-apoptotic CASPASE-3 by the essential oil indicate that eucalyptol and camphor had potent binding compared to the other tested molecules (Figure 7). The binding energies of eucalyptol and camphor were found to be –4.29 and –3.81 kcal/mol, respectively (Table 3). We also observed interactions with the amino acid residues Leu-136 and Lys-137 in chain-A and Thr-195 in chain-B. From the above results, it can be suggested that molecules from EO of *A. lanatum* control liver cancer through apoptotic protein interactions, thus mitigating the migration and angiogenesis of HepG2 liver cancer cell lines.

**Figure 6.** *Cont*.




**Table 2.** *Cont.*

ARG, arginine; HIS, histidine; LEU, leucine; LYS, lysine; MET, methionine; TYR, tyrosine; VAL, valine.

**Figure 7.** In silico docking of binding interactions of the constituents eucalyptol (**A**) and camphor (**B**) from EO of *A. lanatum* against pro-apoptotic protein CASPASE-3. To demonstrate the illustration of interactions in the hydrophobic bond and the other polar bond of CASPASE-3, we show the amino acid residue analysis of interacted bond and its length, together with the binding pocket of ligand–receptor interactions.


**Table 3.** Hydrophobic interaction of potent binding constituents and amino acid residues of target proteins (CASPASE-3).

LEU, leucine; LYS, lysine; TYR, tyrosine.
