Phytochemical insights and green synthesis of silver nanoparticles using Maytenus gracilipes, with evaluation of their antibacterial activity

BACKGROUND: The evergreen shrub Maytenus gracilipes (Celastraceae), used in Ethiopian traditional medicine to treat tonsillitis, ear infections, and malaria, is a promising source for developing antibacterial agents to address antimicrobial resistance. OBJECTIVES: This research investigated the phytochemical composition of M. gracilipes root extract and utilized a green synthesis approach to produce silver nanoparticles. Additionally, it evaluated the antibacterial properties of both the root extract and the synthesized silver nanoparticles. METHODS: C, and DEPT-135 NMR were employed to determine the structures of the isolated compounds. A green synthesis approach was employed to synthesize silver nanoparticles from the root extract of M. gracilipes. The morphology, size, and crystallinity of the silver nanoparticles were confirmed via various techniques, such as X-ray diffraction, scanning electron microscopy, and transmission electron microscopy (TEM). The disc diffusion technique was used to evaluate antibacterial activity. RESULTS: Phytochemical screening revealed the presence of alkaloids, steroids, terpenoids, tannins, and flavonoids, but the absence of anthraquinones in the root extracts of M. gracilipes. Column chromatographic separation of dichloromethane extracts afforded two compounds: a derivative of suberosin (1) and lupeol (2). The X-ray diffraction (XRD) pattern demonstrated that the synthesized silver nanoparticles were crystalline. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the silver nanoparticles are spherical and range from 10 to 60 nm in size. The tested extracts and biosynthesized silver nanoparticles were effective against the tested bacterial strains (Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella typhi) at different concentrations (100, 50, and 25 µg/disc). CONCLUSION: This study demonstrates that M. gracilipes exhibits substantial phytochemical diversity and promising antibacterial activity, emphasizing its potential as a valuable source of bioactive compounds that serve as effective capping agents in nanoparticle synthesis.