In recent years, the green synthesis of silver nanoparticles using various plant extracts has attracted great attention. This is because, these methods are simple, inexpensive and, eco-friendly. In this study, it was observed that silver ions were reduced by phlomis leaf extract after 5 min, leading to the formation of crystalline silver nanoparticles. Phlomis species is known as a rich source of flavonoids, phenylpropanoids and other phenolic compounds. The silver nanoparticles produced by the phlomis extract were characterized by different techniques including UV-vis spectrophotometry, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and FT-IR. The SEM and TEM results indicated that AgNPs were predominantly spherical in shape with an average particle size of 25 nm. In addition, the antibacterial activity of biologically synthesized nanopartilcles against Gram-positive (Staphyloccocus aureus and Bacillus cereus) and Gram-negative (Salmonella typhimurium and Escherichia coli) bacteria was proved. This study, therefore, showed that the phlomis leaf extract could be used for the green synthesis of silver nanoparticles with the appropriate antibacterial activity.

Potential habitat modeling of endemic species is an appropriate method to maintain biodiversity, ecosystem function and rehabilitation of rangeland ecosystems. Astragalus caragana, A. cyclophyllon and A. podolobus are endemic in Iran's rangelands and some neighboring countries. The three native species could endure environmental stresses due to their distinctive ecophysiological characteristics. They play important roles in sustainable pastures production, recreation and improvement. They suffer severe threat from many factors including; grazing, agriculture and invasive exotic species. We analyzed the potential habitat of three native plant species in central Iran basing on the grid map with the resolution of 1-km. We used inventory records from field surveys, herbarium collections and 22 environmental factors to explore the environmental influences on given species distribution by Maximum entropy (Maxent) model. Maxent is a species distribution model that uses species occurrence and environmental data for predicting potential species. The results of our study indicated species occurrence has strong correlation with environmental factors such as mean temperature of wettest season, elevation and precipitation of coldest season. We evaluated the model accuracy by AUC (area under the receiver operating characteristic curve) based on an independent test data set. AUC values indicated the high power of Maxent to create potential habitat map (AUC A. caragana =0.988, AUC A. cyclophyllon =0.927, AUC A. podolobus =0.923). It is important to consider that AUC values tend to be lower for species that have broad distribution scope, such as A. podolobus distribution. Most suitable potential habitat distributions of the three species were predicted in the western and southwestern parts of rangelands in Isfahan province. Visual comparisons of the actual distribution map of the three species with produced Maxent maps represent a good agreement. In general, the model demonstrated that the occurrence of the given species is highly probable when the elevation is between 2,200 and 3,000 m and mean temperature of wettest season less than 3°C. This model, therefore, can be applied to recognize potential sites for rangeland reclamation projects.

The present study focused on the synthesis of spherical silver nanoparticles (Ag NPs) using Gundelia tournefortii L. aerial part extract. The plant extract could reduce silver ions into Ag NPs. To identify the compounds responsible for the reduction of silver ions, functional groups present in plant extract were investigated by Fourier transform infrared spectroscopy. Techniques used to characterise synthesised nanoparticles included field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. UV-visible spectrophotometer showed the absorbance peak in the range of 400-450 nm. The Ag NPs showed antibacterial activities against both gram positive (Staphylococcus aureus and Bacillus Cereus) and gram negative (Salmonella typhimurium and Escherichia coli) microorganisms. The results confirmed that this protocol was simple, rapid, eco-friendly, low-priced and non-toxic; therefore, it could be used as an alternative to conventional physical/chemical methods. Only 5 min were required for the conversion of silver ions into Ag NPs at room temperature, without the involvement of any hazardous chemical.

Silver nanoparticles (SNPs) were synthesised by using the Arial part extract of . and characterised by employing UV-visible spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Transmission electron microscopy and field emission scanning electron microscopy were applied to investigate the morphological structure of the bio-synthesised SNPs. The antimicrobial activity of SNPs was studied against Gram positive ( and ) and Gram-negative ( and ) bacteria by employing the disk diffusion agar process. An extremely antimicrobial effect was observed for SNPs. Utilising as a mediator for the synthesis of SNPs helped to save time and cost.

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In this research, the essential oils obtained from leaves, bulbs and petals of crown imperial plant are used as reducing agents to fabricate silver nanoparticles. The aromatic hydrocarbons, alkenes, ketenes and alkaloids are among the compounds identified in the essential oils as detected by gas chromatography mass spectrometry. The characteristics of silver nanoparticles are investigated by field emission scanning electron microscopy, transmission electron microscopy and XRD. The chemical groups and surface resonance characteristics of the samples are revealed by Fourier transform infrared spectroscopy and UV-Visible spectroscopy, accordingly. The field emission scanning electron microscopy results show that the silver nanoparticles form nanoscale spheres with a mean diameter of 27 ± 14 nm in case of the sample obtained by essential oil of petals as confirmed by transmission electron microscopy. This sample shows a UV-Visible absorption band at 450 nm. The antibacterial activity of the silver nanoparticles shows a remarkable inhibition capability against all of the tested bacteria, with the sample obtained from petals exhibiting the strongest antibacterial effect in agreement with the obtained minimum inhibitory concentration and minimum bactericidal concentration values. The cell viability assay using Vero cell line reveals a nearly constant viability rate above 125 μg/mL of silver nanoparticles.