SILVER NANOPARTICLES OBTAINED FROM GREEN SYNTHESIS APPLIED TO Botrytis cinerea CONTROL

Strawberry is considered one of the most economically important species among small fruits, however, in the production and post-harvest step, the occurrence of gray mold, caused by Botrytis cinerea, may decrease the productivity and final quality of the product. Silver nanoparticles (AgNPs) show well-known antimicrobial activity against several microorganisms due the damage in the respiratory chain within the mitochondria, leading to death cell. Specifically, silver release into the cell may induce the oxidative stress and inhibit the DNA functions, which has proteins with sulfur and phosphorus-containing structures, both with high AgNPs affinity. In this sense, silver nanoparticles (AgNPs) may be used instead as a replacement to synthetic fungicides to control of undesirable microorganisms. Red cherry guava (Psidium cattleianum) is an abundant fruit in Brazil and has a proven content of phenolic compounds with antimicrobial potential and antioxidant capacity. Its extract may be used as reducing agents to prepare nanoparticles from green synthesis, avoiding the use of toxic solvents. Based on these premises, the main objective of this study was to obtain AgNPs using natural extract as a reducing agent and to evaluate its potential against Botrytis cinerea fungus. AgNPs were synthesized from silver nitrate (AgNO3) and extract from red cherry guava (concentrations from 0.1g/mL to 0.001g/mL) and briefly, natural extract was slowly dripped over the AgNO3 solution under constant stirring at 25ºC ± 1°C, and the pH adjusted for 6 to 7.5. After 1 hour, an aliquot was collected, and the nanoparticles formation analyzed in an UV-Vis spectrophotometer at 400-420nm. For the microbiological analysis, inhibition potential of AgNPs against growth of Botrytis cinerea were evaluated at 100 and 200 ppm, while fungus without treatment was used as control. All assays were carried out using mycelial discs (5mm) from an initial culture, transferred to the plates, conditioned in an oven at 27ºC and monitored for 15 days. Results proved the nanoparticle formation by absorbance at 415nm and brown coloring. Concentrations of 100 ppm and 200 ppm showed similar behavior, reaching value of 25% inhibition in relation to control growth. From the data obtained in this work, it was possible to verify the viability of green synthesis to prepare AgNPs as sanitizers systems and its potential against Botrytis cinerea fungus, crediting this technological route to food sanitization, especially those high susceptible to microbial attack.