Green synthesised AuNps using Ajuga Bracteosa extract and AuNps-Free supernatant exhibited equivalent antibacterial and anticancerous efficacies

Abstract

The current study is designed to synthesize gold nanoparticles using Ajuga bracteosa extract, which is a highly known medicinal herb found in the northern Himalayas. The synthesized gold nanoparticles were initially characterized by UV-Vis spectrophotometer, SEM, FTIR, pXRD, and, GC-MS. Antibacterial efficacy of A. bracteosa extract, AuNps, and AuNps-free supernatant activity was checked against highly pathogenic clinical isolates of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa via agar well diffusion method, assuming that supernatant might have active compounds. The Nps-free supernatant showed the maximum antibacterial activity against E. coli (20.8±0.3 mm), Staphylococcus aureus (16.5±0.5), and Pseudomonas aeruginosa (13±0.6). While green synthesized AuNps showed effective antibacterial activity (Escherichia coli (16.4±0.3mm), Staphylococcus aureus (15.05±0.5mm), and Pseudomonas aeruginosa (11.07±0.6mm)) which was high compared to A. bracteosa extract. Anticancer activity was assessed by MTT assay on U87 and HEK293 cell lines. Aj-AuNps have an antigrowth effect on both the cell lines however Aj-AuNps-free supernatant which was also evaluated along with the Aj-AuNps, showed high toxicity toward HEK293 cell line compared to U87. Further, the GC-MS analysis of supernatant showed the presence of resultant toxic compounds after the reduction of gold salt, which include Trichloromethane, Propanoic acid, 2-methyl-, methyl ester, Methyl isovalerate, Pentanoic acid, 2-hydroxy-4-methyl-, Benzene-propanoic acid, and alpha-hydroxy. Based on the observation small molecular weight ligands of Ajuga bracteosa were analyzed in-silico for their binding efficacy towards selected membrane proteins of our target pathogens. RMSD is also calculated for the best docked protein ligand pose. The results revealed that among all listed ligands, Ergosterol and Decacetylajugrin IV have high virtuous binding affinities towards the membrane proteins of targeted pathogens. The current findings revealed that the Aj-AuNps are good antibacterial as well as anticancerous agents while the Nps-free supernatant is also exceedingly effective against resistant pathogens and cancer cell lines.