Table 2.

Calculated potential energy of interaction (ΔE) and free energy of hydration (ΔG) of the drug-HMG box complexes.^a

Compound	ΔE	ΔG
	(kcal/mol)	(kcal/mol)
HMG box - glycyrrhizic acid (GLR)	−82.10	−21.17
HMG box - glycyrrhetinic acid (GA)	−33.62	−14.77

^aIn silico molecular docking procedure. The 3D structure of HMG box [Weir et al., 1993] was retrieved from the Protein Data Bank (www.rcsb.org) under the PDB code 1HME. Docking experiments were performed with the GOLD software (Cambridge Crystallographic Data Centre, Cambridge, UK). The drug-HMG structures have been optimized using a classical Monte Carlo conformational searching procedure as described in the BOSS software (Jorgensen & Tirado-Rives, 2005). Ligands are defined as flexible during the docking procedure. For each ligand, up to 30 poses that are energetically reasonable were kept while searching for the correct binding mode of the ligand. The decision to keep a trial pose is based on ranked poses, using the PLP fitness scoring function (which is the default in GOLD version 5.3 used here). In addition, an empirical potential energy of interaction ΔE for the ranked complexes is evaluated using the simple expression ΔE(interaction) = E(complex) - (E(protein) + E(ligand)). For that purpose, the Spectroscopic Empirical Potential Energy function SPASIBA and the corresponding parameters were used (Lagant et al., 2004; Vergoten et al., 2003). Molecular graphics and analysis were performed using the Discovery Studio 2020 Client software, Dassault Systemes Biovia Corp.