Biological Efficacy of Compounds from Stingless Honey and Sting Honey against Two Pathogenic Bacteria: An In Vitro and In Silico Study

Abstract

Honey inhibits bacterial growth due to the high sugar concentration, hydrogen peroxide generation, and proteinaceous compounds present in it. In this study, the antibacterial activity of stingless and sting honey against foodborne pathogenic bacteria isolated from spoiled milk samples was examined. The isolated bacterial strains were confirmed as Bacillus cereus and Listeriamonocytogenes through morphological, biochemical, and 16 s RNA analysis. Physiochemical characterizations of the honey samples revealed that both of the honey samples had an acidic pH, low water content, moderate reducing sugar content, and higher proline content. Through the disc diffusion method, the antibacterial activities of the samples were assayed and better results were observed for the 50 mg/disc honey. Both stingless and sting honey showed the most positive efficacy against Bacillus cereus. Therefore, an in silico study was conducted against this bacterium with some common compounds of honey. From several retrieved constituents of stingless and sting honey, 2,4-dihydroxy-2,5-dimethyl 3(2H)-furan-3-one (furan) and 4H-pyran-4-one,2,3-dihydro of both samples and beta.-D-glucopyranose from the stingless revealed high ligand-protein binding efficiencies for the target protein (6d5z, hemolysin II). The root-mean-square deviation, solvent-accessible surface area, the radius of gyration, root-mean-square fluctuations, and hydrogen bonds were used to ensure the binding stability of the docked complexes in the atomistic simulation and confirmed their stability. The combined effort of wet and dry lab-based work support, to some extent, that the antimicrobial properties of honey have great potential for application in medicine as well as in the food industries.

Keywords: Bacillus cereus; Listeria monocytogenes; antibacterial activity; honey; molecular docking; molecular dynamics simulation.

Figure 1

Streaking of Isolate A (a) and Isolate B (b) on MacConkey agar.

Figure 2

The zone of inhibition with stingless honey sample (a,b) and sting honey sample (c,d) against the Bacillus cereus and Listeria monocytogenes, respectively.

Figure 3

The effect of pH on the growth of Bacillus cereus and Listeria monocytogenes (a) and the effect of temperature (°C) on the growth of Bacillus cereus and Listeria monocytogenes (b).

Figure 4

Docking simulation between the spike receptor-binding domain of hemolysin II (protein) and 2,4-dihydroxy-2,5-dimethyl 3(2H)-furan-3-one (furan), where (a) shows the cartoon view, (b) surface view, and (c) 2D view.

Figure 5

Docking simulation between the spike receptor-binding domain of hemolysin II (protein) and beta.-D-glucopyranose,1,6-anhydro, where (a) shows the cartoon view, (b) surface view, and (c) 2D view.

Figure 6

Docking simulation between spike receptor-binding domain of Hemolysin II (protein) and l 4H-Pyran-4-one,2,3-dihydro 3,5-dihydroxy-6-methyl, where (a) shows the cartoon view, (b) sur face view, and (c) 2D view.

Figure 7

The simulated systems were analyzed on a time series basis. From (a–e), the RMSD of alpha carbon atoms is denoted by (a), protein volume with the expansion is denoted by (b), rigidity and compactness of the complexes are represented by (c), hydrogen bonding is represented by (d), and the flexibility of amino acid residues is denoted by (e).