Table 1 Top ten screened natural compounds, their corresponding binding free energies, types of interactions, and the amino acid residues in the transmembrane histidine kinase involved in interactions

1. 

ZINC000085569031

 − 14.4

Conventional hydrogen bond, Pi-cation, Pi-anion, and alkyl bond, Unfavorable positive-positive

Arg268, Gln271, Leu336, Asp438, Arg439, Lys464, Ala469

2. 

ZINC000257435291

 − 14.2

Attractive charge, conventional hydrogen bond, Carbon hydrogen bond, Unfavorable positive-positive, Unfavorable negative-negative

Tyr265, Arg268, Gln333, Glu337, Gln340, Arg439, Ser461

3.

ZINC000150351499

 − 13.9

Attractive charge, conventional hydrogen bond, pi-sigma, pi-alkyl, Unfavorable positive-positive

His290, Ala310, Glu315, Arg318, Glu450

4.

ZINC000253530205

 − 13.9

Attractive charge, carbon hydrogen bond, pi-cation, alkyl, pi-alkyl

Arg268, Ile273, Leu336, Asp468, Ala469

5.

ZINC000257787835

 − 13.9

Attractive charge, conventional hydrogen bond, pi-cation, pi-anion, pi-sigma, pi-pi t-shaped, pi-alkyl

Arg268, Gln333, Leu336, Asp468, Ala469, His471

6.

ZINC000253529638

-13.8

Attractive charge, conventional hydrogen bond, pi-cation, pi-anion, pi-sigma, pi-pi t-shaped, pi-alkyl

Val286, His290, Ala311, His314, Glu315, Arg318, Glu450

7.

ZINC000150359935

 − 13.8

Attractive charge, conventional hydrogen bond, pi-pi t-shaped, alkyl, pi-alkyl, unfavorable positive-positive

Leu336, Phe435, Lys464, Asp468, Ala469, His471

8.

ZINC000276935378

 − 13.8

Attractive charge, conventional hydrogen bond, carbon hydrogen bond, pi-cation, unfavorable positive-positive

Glu279, Arg318, Arg447, Leu456

9.

ZINC000253531178

-13.6

Attractive charge, carbon hydrogen bond, alkyl, pi-alkyl

Arg268, Ile273, Leu336, Ala469, Asp468

10.

ZINC000085569053

 − 13.6

Attractive charge, conventional hydrogen bond, pi-cation, pi-anion, alkyl, unfavorable positive-positive

Arg268, Gln271, Leu336, Asp438, Arg439, Lys464, Ala469