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Introduction: Drimia numidica is a polyphenol-rich species that has antioxidant capacity, which makes it very important. Nevertheless, D. numidica has not been studied in depth. Moreover, its capsules have not been studied so far. This detailed study compared the values of total phenolic content and antioxidant activity of all D. numidica parts (scapes, flowers, bulbs, capsules, leaves, roots), from Edough Peninsula, Annaba, Algeria, using hydromethanol extracts and their fractions (cyclohexane, chloroform, ethyl acetate, and n-butanol). Methods: The total phenolic content was determined by Folin Ciocalteo assay, and the antioxidant activity by the following methods: DPPH, Reducing Powder, Phenanthroline, Silver Nanoparticles, CUPRAC, and ABTS. Statistical analysis was done using the ANOVA test and a correlation test (between antioxidant activity and total phenolic content). Results: The Ethyl acetate fraction was found the sample with the highest phenolic content. The same was true for the antioxidant activity in all tests except for the silver nanoparticles test in which cyclohexane extracts scored the best. Considering the methods used in general, there is a correlation between phenolic content and the highest antioxidant activity, but there are some methods that have not recorded any correlation. Conclusion: Choosing the appropriate method or extract/fraction type is extremely important. In addition, extracts of D. numidica parts could be an important natural alternative to antioxidants industrial. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are a promising technology for the design of antimicrobial agents against drug-resistant pathogens. It could also be used for the photocatalytic degradation of dyes used in industries such as methylene blue (MB). In this study, 17 different actinomycetal strains isolated from hydrocarbon-contaminated soils collected from an oil distribution company in Algeria were evaluated for their ability to produce NPs. After a selection process, S16 was the main strain capable of synthesizing AgNPs extracellularly. The strain S16 was determined using molecular identification based on the sequencing of the 16S rDNA gene. Among various techniques used for the synthesis of AgNPS, a technique using a temperature of 30 °C, pH of 7, a metal salt concentration of 1 mM, and a period of 72 h in the dark were found to be more effective in the biosynthesis of the AgNPs. The biosynthesized AgNPs that were analyzed by UV–visible spectroscopy resulted in a specific peak at a wavelength of (λ = 400 nm). The DRX analyses showed characteristic peaks of the AgNPs at (1 1 1), (2 0 0), (2 2 2), and (3 1 1), which validated the presence and crystalline nature of the biosynthesized NPs. Zetasizer analysis showed an average size and zeta potential of 64 nm (−32.3 mV), while the SEM-EDS analysis confirmed the spherical shape of AgNPs and the presence of Ag atoms in the elemental composition. The biosynthesized AgNPs indicated adequate antibacterial activity against 5 out of the 6 strains tested in this study, using minimum inhibitory concentration (MIC) that ranged from 217.18 μg/mL to 1137.5 μg/mL. The AgNPs were combined with commercial antibiotics and the synergistic effect of the combination was also assessed against MRSA which resulted in increased antibacterial activity of AgNPs in the presence of the strain S16. Furthermore, the photocatalytic degradation of the methylene blue (MB) was evaluated under sunlight and UV irradiations using biosynthesized AgNPs. The AgNPs showed photocatalytic decolorization potential of 71.3% for MB dye (20 ppm) under sunlight irradiation within 6 h of incubation, while only 11.25% of the MB dye degraded using UV irradiation. • Seventeen different actinomycetal strains were tested to produce nanoparticles. • S16 strain was well able to synthesize Ag nanoparticles extracellularly. • The antibacterial efficacy was enhanced in the presence of AgNPs of the S16 strain. • The AgNPs nanoparticles succeeded in the photocatalytic degradation of MB dye. [ABSTRACT FROM AUTHOR]

As nanoparticles have been found to cause a range of harmful impacts in biota, understanding processes and transformations which may stabilize and increase their persistence time in the environment are of great importance. As nanoparticles carried in riverine or wastewaters will eventually reach estuaries, understanding their behavior and transport potential in this transition zone from fresh to marine waters is essential, particularly as estuaries are sensitive ecological zones, oftentimes encompassing ornithologically important areas. In this direction, we report on the influence of combined gradients of riverine and marine natural organic matter (NOM) on the temporal stability of biocorona-encapsulated silver nanoparticles in terms of ion release kinetics. In parallel, salinity, pH and oxygen saturation were simultaneously varied to create a model to mimic the complex estuarine environment. While humic acid (HA) and alginate (Alg) disrupted the stabilizing ability of the nanoparticle protein corona to a greater and lesser degree, respectively, they slowed the rate of ion release in freshwater at pH 6.6 and in saltwater at pH 8, respectively, while oxygen saturation was also found to be an important factor. Thus, as the type of NOM changes with pH along a salinity gradient in an estuary, conditions required to increase the persistence time of nanoparticles are serendipitously met, with greater colloidal stability achieved in cases where there is more rapid replacement of HA with Alg. Despite the strong gradients in ionic strength, pH and oxygen saturation, the protein corona was not sufficiently disrupted at the nanoparticle surface to be substituted by NOM indicating the greater adsorption energy of the protein's hydrophobic domains. Ultimately, it is the specific NOM profile of individual estuaries that may provide the best indicator for predicting the stability and persistence of silver nanoparticles as they transition from fresh to salt water environments. [ABSTRACT FROM AUTHOR]