Systematic antimicrobial, biofilm, free radical inhibition and tyrosinase inhibition assessments of efficient green silver nanoparticles from the aqueous root extract of Cyphostemma adenocaule (CA)

Abstract

A novel, fast and optimized etiquette for the production of silver nanoparticles using the root extract of Cyphostemma adenocaule (CA) is reported in our study. This plant is known to possess many natural terpenes, glycosides and sterols, which can reduce AgNO₃ solution. Typical physiochemical analyses like UV-spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FTIR) were used to characterize and confirm the synthesis of the produced nanoparticles. The XRD and TEM analyses validated that the obtained particles were spherical shaped with the average size of 18 nm. The CA–AgNPs depicted excellent anti-bacterial activity against the studied gram (+ve) and (−ve) microorganisms and showed a very good S. aureus biofilm in a dose-dependent response (a maximum inhibition of 88% at a 125 μg mL⁻¹ dose). Further results proved its ability to neutralize ABTS free radicals (96.5% neutralization was noted at a 200 μg mL⁻¹ dose with the IC₅₀ value of 48.62 μg mL⁻¹) and mushroom tyrosinase enzyme (tyrosinase is the enzyme responsible for hyperpigmentation) inhibition from 34.25% ± 3.68% to 90.90% ± 3.45%, with the highest activity at 100 μg mL⁻¹. The above results indicate the potential of silver nanoparticles as antibacterial and antioxidant agents and tyrosinase inhibitors in the food, cosmetics and medicinal industries.