Green synthesis and evaluation of antipathogenic, antioxidant, and anticholinesterase activities of gold nanoparticles (Au NPs) from Allium cepa L. peel aqueous extract

Gold nanoparticles (Au NPs) have potentially therapeutic properties as they are synthesized via biomolecules as reducing and stabilizing agent(s). The aim of this study is to develop an easy and eco-friendly method for the synthesis of Au NPs using extracts from the Allium cepa (AC) red peel (skin) extract and investigate the antibacterial and antioxidant activity and also inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. UV–Vis peak at ~ 564 nm confirmed the Au NPs absorbance. TEM images revealed the formation of Au NPs with mostly spherical shapes and sizes between 6.08 and 54.20 nm. FTIR analysis confirmed the important biological compounds responsible for the reduction of gold. The strong absorption property of Au NPs was studied by EDX. The produced Au NPs demonstrated significant antibacterial and antifungal activity against the bacterial and fungal strains tested, as well as efficient inhibitory activity against both AChE and BChE enzymes. The highest antimicrobial activities were found against Staphylococcus aureus (0.06° mg/ml) and Candida albicans (0.06° mg/ml). The antioxidant test findings revealed that AC-Au NPs had lesser activity when compared to normal antioxidants. The Au NPs showed excellent inhibitory efficacy against AChE and BChE. The proposed green technique could encourage the innocuous generation of Au NPs, implying therapeutic possibilities.