Table 2. Binding energy and amino acid residues that participated in the binding.

Ligand	Binding energy (kcal/mol)	Binding residue
Collagenase inhibitor
Caffeic acid	−6.86	Glu524, Tyr496, His527, Trp539, Glu498, Glu555, His523, Ile497, Leu495, Pro499
Bisresorcinol	−5.89	Asp601, Glu498, Ser602, Tyr496, Trp539, Asp603, Gln530, Glu524, Glu555, Gly494, Ile497, Pro499, Thr551, Trp604, Tyr607, Ser597, Zn1791
Elastase inhibitor
Ursolic acid	−8.94	Asn192, Ser96, Asn97, Gly216, Phe215, Ser190, Ser195, Ser214, Ser217, Thr146, Trp94, Val213
Bisresorcinol	−5.69	Asn147, Phe215, Ser190, Ser217, Asn192, Arg143, Gly216, Gly219, His57, Ser189, Ser195, Ser214, Ser226 Thr146, Val213, Val227
Tyrosinase inhibitor
β-arbutin	−5.52	His259, His263, Zn401 Asn260, Ser282, Val283, His61, His85, His94, His296, Phe90, Phe264, Phe292, Pro284
Bisresorcinol	−6.57	Arg321, Ala246, Glu239, Met280, His263, Asn243, Asn260, Glu322, Gly86, Gly281, His61, His85, His94, His251, His259, His296, Met319, Phe292, Ser282, Thr87, Val248, Zn400

Note:

π-cation, π-π stacking, and hydrogen bonds were depicted in italic, underline, and bold, respectively. The normal letter represented amino acids containing and Van der Waals interactions with the compound.