Frankincense, an aromatic medicinal exudate of Boswellia carterii used to mediate silver nanoparticle synthesis: Evaluation of bacterial molecular inhibition and its pathway

Green synthesized silver nanoparticles (AgNPs) are expected to have rich biomedical applications as an alternative medicine for health care, with the bioactive compounds of plants acting as moderating agents in the synthesis of silver nanoparticles with high therapeutic potential. In this study, frankincense (also known as Alliban in Arabic), which is a resin obtained from the bark of the tree Boswellia carterii and a traditional alternative medicine, was used as a moderating agent. The synthesized silver nanoparticles [BW-AgNPs] were characterized using UV-vis, EDAX, FT-IR, and SEM analyses. The antimicrobial activities of the synthesized nanoparticles were tested against Streptococcus mutans, Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. Additionally, the anti -S. mutans activities were traced at the molecular level; the impact of the nanoparticles on eight functional genes, brpA, comDE, spaP, smu360, gtfB, gtfCc, gtfDd and gbpB, was probed; and the minimum inhibitory concentration was quantified using microdilution and resazurin staining techniques. The diameter of the zone of inhibition for S. mutans was 22.0 mm at 200 mu g/NP treatment, and the SEM study showed that the NPs were irregular to spherical. The size range of the synthesized NPs was 14.19-85.36 nm, with an average of 14.8 +/- 0.3 nm based on the TEM study. The FTIR spectra of crude frankincense and frankincense mediated AgNPs showed peak bands with closely related wavelengths, which indicates that frankincense participates as capping and surface-attached components in the NPs. The NPs showed high antibacterial action against the oral pathogen S. mutans, which causes dental caries. This finding may promote the development of commercial products that incorporate NPs, such as toothpaste and mouth wash. NPs in a size range of less than 30 nm have been reported to easily target SARS-CoV-2; thus, the AgNPs synthesized here with a size range of 14.188-15.202 nm may pave the way for further research.