Biosynthesis and activity of Zn- MnO nanocomposite in vitro with molecular docking studies against multidrug resistance bacteria and inflammatory activators

This study investigated the green synthesis of Zn-MnO nanocomposites via the fungus Penicillium
rubens. Herein, the synthesized Zn-MnO nanocomposites were confirmed by UV-spectrophotometry
with a top peak (370 nm). Transmission electron microscopy confirmed irregular particles with a
spherical-like shape ranging from 25.13 to 36.21 nm. Numerous functional groups were detected
on the surface of Zn-MnO nanocomposite via Fourier-transform infrared spectroscopy. X-Ray
diffraction assay appeared that the synthesized Zn-MnO nanocomposites contained two different
components, MnO (JCPDS 81-2261) and ZnO (JCPDS 36-1451), while energy dispersive X-ray spectra
confirmed the occurrence of manganese, zinc, oxygen, and carbon in Zn-MnO nanocomposites.
Zn-MnO nanocomposites demonstrated excellent suppress effect versus the growth of various
bacteria namely Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Salmonella typhi, and
Klebsiella pneumoniae via agar well diffusion assays with inhibition areas of 36 ± 0.1, 25 ± 0.1, 27 ± 0.2,
and 23 ± 0.2 mm, correspondingly. Alterations in the ultrastructure of the treated K. pneumoniae by
Zn-MnO nanocomposite were recorded. Both the values of minimum inhibitory concentration (MIC)
and minimum bactericidal concentration of Zn-MnO nanocomposite extended from 15.62 to 125 μg/
mL employing the examined bacteria. The antibiofilm activity of Zn-MnO nanocomposites was 82.07,
75.43, 43.65, and 41.35% at 25% MIC, and 96.54, 93.0, 94.53, and 91.11% at 75% MIC against S.
aureus, MRSA, K. pneumoniae, and S. typhi, respectively. At 25 to 75% MIC, Zn-MnO nanocomposites
exhibited antihemolytic activity with the maximum activity of 96.3% at 75% MIC in the presence
of MRSA. Extensive molecular docking studies were performed to identify the optimal location for
manganese oxide and zinc oxide nanoclusters binding to MRSA. MnO-NPs and ZnO-NPs demonstrated
inhibitory activity against the crystal structure of putative minohydrolase (PDB ID: 4EWT), methicillin
acyl-penicillin binding protein 2a structure (PDB ID: 1MWU) and K2U bound crystal structure of class II
peptide deformylase from MRSA (PDB ID: 6JFQ). The minimum binding energy was utilized to estimate
the receptor’s binding site with NPs, providing additional understanding of the ways of action.
Anti-inflammatory activity of Zn-MnO nanocomposites via cyclooxygenase-1 and cyclooxygenase-2
enzymes inhibition was documented with IC50 doses of 20.81 ± 0.68 μg/mL and 35.87 ± 1.35 μg/mL,
respectively. Based on these outcomes, it was concluded that Zn-MnO nanocomposites could be useful
agents for the management of multidrug resistant bacterial pathogens and inflammation.