Stachys lavandulifolia and Lathyrus sp. Mediated for Green Synthesis of Silver Nanoparticles and Evaluation Its Antifungal Activity Against Dothiorella sarmentorum

Abstract

In this study, silver nanoparticles (AgNPs) were biosynthesized using Stachys lavandulifolia and Lathyrus sp. The first sign of the reduction of silver ions to AgNPs was the change in color of S. lavandulifolia and Lathyrus sp. extracts changed into dark brown and auburn after treating with silver nitrate, respectively. The UV–Vis spectroscopy of reaction mixture (extract+silver nitrate) produced by S. lavandulifolia and Lathyrus sp. showed the strong adsorption peaks at ≃440 and 420 nm, respectively. The transmission electron microscope images showed the synthesis of AgNPs using S. lavandulifolia and Lathyrus sp. with an average size of 7 and 11 nm, respectively. The result of X-ray diffraction pattern showed four diffraction peaks at 38°, 44°, 64°, and 77° for both types of biosynthesized AgNPs. Fourier transform infrared spectroscopy showed the possible role of involved proteins and polyhydroxyl functional groups in the synthesis process of AgNPs. Inductively coupled plasma analysis determined the conversion rate (percentage) of silver ions to silver nanoparticles in reaction mixtures of S. lavandulifolia and Lathyrus sp. 99.73 and 99.67 %, respectively. In addition, antifungal effect of AgNPs, synthesized by both extracts, was studied separately on mycelial growth of Dothiorella sarmentorum, in a completely randomized design on potato dextrose agar (PDA) medium. The inhibition rate of mycelial growth was strongly depended on the density of AgNPs and it strongly increased with increasing the density of AgNPs in the PDA medium. AgNPs more than 90 % of them inhibited from the mycelia growth of the fungus at the concentration of 40 µg/mL and higher.