Green synthesis of gold nanoparticles using Damiana induce antiseptic activity against gram-negative bacteria

Interest in green synthesis methods for nanoparticle production with potential use in biology, pharmacy, and medicine is a forefront field in research. Among the routes described in the literature, the use of plant extracts as reducing and capping agents is one of the most promising. Turnera diffusa commonly called Damiana is a wild shrub traditionally used as aphrodisiac, diuretic, and for cancer and diabetes treatments. Its extracts are rich in flavonoid, phenolic, terpenoid, and other active compounds that possess antiallergic, antiviral, and antifungal activities. Besides, flavonoids have been reported to have a redox potential sufficient for metal ion reduction. Thus, this study reports a novel and facile method for green gold nanoparticle (AuNPs) synthesis using T. diffusa extracts. The samples were fully characterized by scanning electron microscopy, acrylonitrile butadiene styrene ultraviolet-visible, dynamic light scattering, X-ray photoelectron, and inductively coupled plasma optical emission spectroscopies. The results showed high efficiency of T. diffusa extracts to reduce and stabilize the AuNPs which showed spherical shape, 24 nm diameter, negative surface charge, and high colloidal stability at biological pH and alkaline media. Additionally, its antimicrobial activity was evaluated showing high antiseptic capacity against gram-negative Salmonella enteritis and Escherichia coli ATCC 8739 bacteria.