Table 3. Summary of the binding interactions and energies of active xanthone with CDK2, PBP2a of MRSA, and SCWP O-acetyltransferase of B. cereus.

Compound	Binding energy (kcal mol−1)	Protein-ligand interactions
		Hydrogen bond	Hydrophobic	Electrostatic
Interactions of xanthone with CDK2
1	−8.62	Glu81, Leu83, Asp86	Ile10, Ala31, Phe82, Lys89, Leu134, Ala144	—
1a	−9.43	Lue83, Asp86, Asp145	Ile10, Ala31, His84, Lys89, Leu134, Ala144	—
1b	−9.78	Asp86, Lys89	Ile10, Val18, Ala31, Phe80, Phe82, Leu134, Ala144	—
1f	−8.52	Leu83, His84, Gln131	Ile10, Val18, Ala31, Phe80, Phe82, Ala144, Lue134	—
RC-3-89	−10.51	Glu81, Leu83, Asp86, Lys89	Ile10, Val18, Ala31, Phe82, Leu134, Ala144, Asp145	—
Interactions of xanthone with PBP2a of MRSA
1a	−8.02	Ser403, Glu602, Asn464, Met641	Tyr446, His583, Ala642	—
1f	−7.29	Ser403, Ser462, Ser598	Asn464, Tyr519, Met641	—
Tatracycline	−8.35	Ser403, Tyr444, Try446, Ser462, Asn464, Ser598	Gln521, Ala646, Met641	—
Interactions of xanthone with B. subtilis LCP enzyme
1a	−7.55	Thr197, Arg210, Gln214	Asp75, Asp85, Arg106, Arg210	Asp75, Asp85
1f	−7.32	Gln211	Pro105, Arg106, Asp207, Phe208, Leu273, Tyr286	Asp107, Asp207
Tatracycline	−5.86	Asp75, Arg210, Gln214	Asp75, Asp85, Arg198, Arg210	Arg198
Interactions of xanthone with SCWP O-acetyltransferase of B. cereus
1a	−7.18	Lys103, Asn104, Asn251, Arg359	His201, His202, Ser249, Phe250	His201
1f	−6.97	Lys103, Asn251, Ser385	His201	Asp92, His201, Arg359
Tetracycline	−5.75	Lys103, Asn104, Asn251, Ser385	His201, His202, Asn386	Arg359