Flavonoid-coated gold nanoparticles as efficient antibiotics against gram-negative bacteria—evidence from in silico-supported in vitro studies

Hani A. Alhadrami, Raha Orfali, Ahmed A. Hamed, Mohammed M Ghoneim, Hossam M. Hassan, Ahmed S. I. Hassane, Mostafa E. Rateb, Ahmed M. Sayed*, Noha M. Gamaleldin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Flavonoids are a class of bioactive plant-derived natural products that exhibit a broad range of biological activities, including antibacterial ones. Their inhibitory activity toward Gram-positive bacterial was found to be superior to that against Gram-negative ones. In the present study, a number of flavonoid-coated gold nanoparticles (GNPs) were designed to enhance the antibacterial effects of chrysin, kaempferol, and quercetin against a number of Gram-negative bacteria. The prepared GNPs were able to conjugate to these three flavonoids with conjugation efficiency ranging from 41% to 80%. Additionally, they were able to exert an enhanced antibacterial activity in comparison with the free flavonoids and the unconjugated GNPs. Quercetin-coated GNPs were the most active nano-conjugates and were able to penetrate the cell wall of E. coli. A number of in silico experiments were carried out to explain the conjugation efficiency and the antibacterial mechanisms of these flavonoids as follows: (i) these flavonoids can efficiently bind to the glutathione linker on the surface of GNPs via H-bonding; (ii) these flavonoids, particularly quercetin, were able to increase the bacterial membrane rigidity, and hence decrease its functionality; (iii) these flavonoids can inhibit E. coli’s DNA gyrase (Gyr-B) with IC50 values ranging from 0.9 to 3.9 µM. In conclusion, these bioactive flavonoid-based GNPs are considered to be very promising antibiotic candidates for further development and evaluation.
Original languageEnglish
Article number968
Number of pages17
JournalAntibiotics
Volume10
Issue number8
DOIs
Publication statusPublished - 12 Aug 2021

Keywords

  • gold nanoparticles
  • flavonoids
  • gram-negative bacteria
  • DNA gyrase
  • in silico

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