Silver nanoparticles obtained from Brazilian pepper extracts with synergistic anti-microbial effect: production, characterization, hydrogel formulation, cell viability, and in vitro efficacy

Abstract

The synthesis of silver nanoparticles using plant extracts is known as a green approach, as it does not require the use of high pressure, energy, high temperature, or toxic chemicals. The approach makes use of plant extracts in a process called bioreduction, which is mediated by enzymes, proteins, amino acids, and metabolites found in bark, seed, and leaf extracts, transforming silver ions into metallic silver. This work aimed at developing silver nanoparticles (AgNPs) from Brazilian pepper, applying this green methodology. Hydroalcoholic extract of leaves of Schinus terebinthifolius Raddi was prepared and its concentration of polyphenols, tannins, and saponins quantified. The produced nanoparticles were characterized by UV-Vis spectroscopy, thermogravimetric analysis (TG), dynamic light scattering (DLS), and zeta potential (ZP). AgNPs were formulated in sodium alginate hydrogels to obtain a nano-based semi-solid formulation for skin application. The obtained silver nanoparticles of mean size between 350 and 450 nm showed no cytotoxicity against L929 mouse fibroblasts within the concentration range of 0.025 mg/mL and 10 mg/mL. Schinus terebinthifolius Raddi was found to enhance microbial inhibition against the tested strains, especially against gram-negative bacteria. Its potential use as an alternative to overcome bacterial resistance can be expected.

Keywords:

• Brazilian pepper
• Schinus terebinthifolius Raddi
• silver nanoparticles
• green synthesis
• bacterial infections
• microbial resistance

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Banco do Nordeste do Brazil [FUNDECI/2016.0015], Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), [443238/2014-6 and 470388/2014-5], Fundação de Apoio à Pesquisa e à Inovação Tecnológica do Estado de Sergipe (Fapitec), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and the Fundação para a Ciência e a Tecnologia (FCT/MCT) and from European Funds (PRODER/COMPETE) for the projects M-ERA-NET/0004/2015-PAIRED and UIDB/04469/2020 (strategic fund), co-financed by FEDER, under the Partnership Agreement PT2020.