Licaria puchury-major (MART.) kosterm: biossíntese de nanopartículas de prata dos extratos vegetais com atividade antimicrobiana

Abstract

Currently the use of green chemistry for the synthesis of nanoparticles become an alternative in the area of nanotechnology. Plants store many bioactive compounds, and the interaction between the biochemistry of plants and inorganic nanoparticles tends to be promising in this area. Several studies report on the use of plant extracts in the biosynthesis of silver nanoparticles (AgNPs) in order to investigate clinical applications active on various micro-organisms, the effectiveness certain plant species show as sources of antimicrobial and the reduced toxicity compared to biosynthesized nanoparticles by chemical and physical methods. This study aims to investigate the statements of Licaria puchury-major to AgNPs biosynthesis with antimicrobial activity. This work was carried out in three stages. In stage I, was selected the promising method of extraction through biosynthesized AgNPs with the aqueous extracts of the anatomical structures of leaf, branch, seed, cupola, bark and root for the cold extraction methods (ambient temperature 25-27 °C), infusion (<100 °C for 15 min) and decoction (100 °C for 15 min). The selection was made through the formation of AgNPs indicated by changing the color of the colloidal solutions and Spectroscopic Analysis in the Ultraviolet-Visible Region (UV-vis) and antimicrobial activity determined by the diffusion technique in agar against micro-organisms Staphylococcus aureus, Escherichia coli and Candida albicans. The AgNPs selected at this stage were investigated to check stability after six months and washing system. Step II - it was characterized the extracts of the silver nanoparticles obtained by extraction promising method (infusion). The techniques employed for the characterization of the extracts were quantified phenolics, and flavonoids total protein; Vibrational Spectroscopy in the Infrared Fourier Transform Spectroscopy (FTIR); High Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS). The AgNPs were characterized by Spectroscopy in the Ultraviolet-Visible Region (UV-vis), for Analysis of Dynamic Light Scattering (DLS), Atomic Emission Spectroscopy with Inductively Coupled Plasma (ICP-OES), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). In step III, the antimicrobial activity of promising nanoparticle selected by characterization was evaluated determined by agar diffusion techniques and the Minimum Inhibitory Concentration (MIC) using only the micro-organisms present action. The results showed: Step I - was selected as a promising method for infusion, obtained by UV-vis Analysis, stability and antimicrobial; Step II - characterization of the extracts obtained by the infusion method, shown for aborted seed extract the highest levels of phenolic compounds, flavonoids and proteins: (388 ± 5 mg.g-1), (447 ± 3 ug.ml-1) and (116 ± 8 μg.mL-1), respectively. The spectra and data obtained from HPLC and MS, the presence of licarina neolignans A was suggested ferrearina B and C only in the leaf extract. The characterization made by TEM showed that AgNPs biosynthesized by the infusion method showed no significant difference in size: 57.0 ± 7 nm (AgNPs -FI), 60 ± 14 nm (AgNPs -CI), 56 ± 13 nm (AgNPs- SI) and 60 ± 18 nm (AgNPs -SabI); or morphologies, all presented triangular shapes, truncated triangular- and pseudospherical. The presence of the protein in the extract can be responsible for the formation of the layer around the AgNPs and stabilization. The AgNPs -FI was promising nanoparticle which, in step III showed antimicrobial activity in the concentration 17.23 mg.L-1 indicated by halo 19 ± 0.0 mm against S. aureus; and 17 ± 0,0 mm against E. coli. The MIC was 10 μg.mL-1 for S. aureus and 0.625 μg.mL-1 for E. coli. The biosynthesis using the aqueous extract of L. puchury-major sheet obtained by the infusion method can be a sustainable alternative for the production of nanoparticles with biotechnological applications as an antimicrobial.