Investigation of the Antibacterial Activity and in vivo Cytotoxicity of Biogenic Silver Nanoparticles as Potent Therapeutics

Abstract

Biogenic nanoparticles are the smartest weapons to deal with the multidrug-resistant “superbugs” because of their broad-spectrum antibacterial propensity as well as excellent biocompatibility. The aqueous biogenic silver nanoparticles (Aq-bAgNPs) and ethanolic biogenic silver nanoparticles (Et-bAgNPs) were synthesized using aqueous and ethanolic extracts of Andrographis paniculata stem, respectively, as reducing agents. Electron microscopic images confirmed the synthesis of almost spherical shaped biogenic silver nanoparticles (bAgNPs). The zeta potentials of the nanoparticles were negative and were −22 and −26 mV for Aq-bAgNPs and Et-bAgNPs, respectively. The antibacterial activity of bAgNPs was investigated against seven pathogenic (i.e., enteropathogenic Escherichia coli, Salmonella typhi, Staphylococcus aureus, Vibrio cholerae, Enterococcus faecalis, Hafnia alvei, Acinetobacter baumannii) and three nonpathogenic (i.e., E. coli DH5α, E. coli K12, and Bacillus subtilis) bacteria at different time points (i.e., 12, 16, 20, and 24 h) in a dose-dependent manner (i.e., 20, 40, and 60 μg) through broth dilution assay, disk diffusion assay, CellToxTM Green uptake assay, and trypan blue dye exclusion assay. The lowest minimum inhibitory concentration value for both the bAgNPs was 0.125 μg. Et-bAgNPs showed the highest antibacterial activity against S. aureus at 60 μg after 16 h and the diameter of inhibited zone was 28 mm. Lipid peroxidation assay using all the bacterial strains revealed the formation of malondialdehyde–thiobarbituric acid adduct due to the oxidation of cell membrane fatty acids by bAgNPs. The bAgNPs showed excellent hemocompatibility against human as well as rat red blood cells. Furthermore, there was no significant toxicity observed when the levels of rat serum ALT, AST, γ-GT (i.e., liver function biomarkers), and creatinine (i.e., kidney function biomarker) were determined.

Investigation of the Phytoconstituents and Antioxidant Activity of <i>Diospyros malabarica</i> Fruit Extracts

“…The extracts showed antioxidant activity according to the following order: aqueous seed extract > ethanolic seed extract > ethanolic flesh extract > aqueous flesh extract >> hexane extracts. According to Aparadh et al [49] and Hossain et al [50], antioxidant activity of plant extracts depend on the presence of respective secondary metabolites, such as flavonoids, tannins and phenolics. Another study reported that vitamin C is the indicator of antioxidant activity [30].…”

Antimicrobial and Antibiofilm Activities of New Synthesized Silver Ultra-NanoClusters (SUNCs) Against Helicobacter pylori

“…In general, the higher cytotoxicity of smaller nanoparticles can be explained by different chemical-physical properties occurring when the particle is formed by a lower aggregation of atoms. As an example, we can consider the observed increased ROS production of small nanoparticles as compared to that generated by the greater ones (Hossain et al, 2019). Other mechanisms associated with these silver-containing nanosystems are the disruption of the bacterial membrane, uncoupling of the respiratory electron transport, morphological changes (cytoplasm membrane detachment), DNA replication impairment, and protein expression alteration (Durán et al, 2016;Tang and Zheng, 2018).…”

Nanoparticle-Based Devices in the Control of Antibiotic Resistant Bacteria

“…For instance, AgNPs have shown good in vitro compatibility with human and murine erythrocytes (Hossain et al, 2019), but they do exhibit toxicity to peripheral blood mononuclear cells (PBMCs; Shin et al, 2007). Moreover, in vivo studies on zebra fish made by Bao and colleagues show that AgNPs induce pathological changes on growth indices, oxidative/antioxidative status, neural signaling, Na/K-ATPase function, and antioxidant system in the intestine, but not in the liver, with male zebrafish being more sensitive than female (Bao et al, 2020).…”