Silver Nanoparticle Effects on Antioxidant Response in Tobacco Are Modulated by Surface Coating

Synthesis, Characterization, Phytochemistry, and Therapeutic Potential of Azadirachta indica Conjugated Silver Nanoparticles: A Comprehensive Study on Antidiabetic and Antioxidant Properties

Nanotechnology has become a major topic of study, particularly in the medical and health domains. Because nanomedicine has a higher recovery rate than other conventional drugs, it has attracted more attention. Green synthesis is the most efficient and sustainable method of creating nanoparticles. The current work used ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray, and X-ray diffraction to thoroughly characterize the synthesized silver nanoparticles (AgNPs) from Azadirachta indica leaf extract. Characterization confirmed the synthesis of the AgNPs along with the possible linkage of the phytochemicals with the silver as well as the quantitative analysis and nature of NPs. The antioxidant activity of AgNPs and neem extract was measured by the 2,2-diphenyl-1-picrylhydrazyl assay using various concentrations (20, 40, 60, 80, and 100 µg/ml). Additionally, using diabetic mice that had been given alloxan, the in vivo antidiabetic potential of biosynthesized AgNPs was assessed. Eight groups of mice were used to assess the antidiabetic activity: one control group and seven experimental groups (untreated, extract-treated, AgNPs at low and high doses, standard drug, low dose of AgNPs + drug, and high dose of AgNPs + drug). At days 0, 7, 14, 21, and 28, blood glucose levels and body weight were measured. After 28 days, the mice were dissected, and the liver, kidney, and pancreas were examined histologically. The results depicted that the AgNPs showed higher (significant) radical scavenging activity (IC50 = 35.2 µg/ml) than extract (IC50 = 93.0 µg/ml) and ascorbic acid (IC50 = 64.6 µg/ml). The outcomes demonstrated that biosynthesized AgNPs had a great deal of promise as an antidiabetic agent and exhibited remarkable effects in diabetic mice given AgNPs, extract, and drug. Remarkable improvement in the body weight and blood glucose level of mice treated with high doses of AgNPs and drug was observed. The body weight and blood glucose level of diabetic mice treated with a high dose of AgNPs + standard drug showed significant improvement, going from 28.7 ± 0.2 to 35.6 ± 0.3 g and 248 ± 0.3 to 109 ± 0.1 mg/dl, respectively. Significant regeneration was also observed in the histomorphology of the kidney, liver's central vein, and islets of Langerhans after treatment with biosynthesized AgNPs. Diabetic mice given a high dose of AgNPs and drug displayed architecture of the kidney, liver, and pancreas that was nearly identical to that of the control group. According to the current research, biosynthesized AgNPs have strong antioxidant and antidiabetic potential and may eventually provide a less expensive option for the treatment of diabetes.

Influence of Silver Nanoparticles on the Metabolites of Two Transgenic Soybean Varieties: An NMR-Based Metabolomics Approach

This study investigated the effect of AgNPs and AgNO3, at concentrations equivalent, on the production of primary and secondary metabolites on transgenic soybean plants through an NMR-based metabolomics. The plants were cultivated in a germination chamber following three different treatments: T0 (addition of water), T1 (addition of AgNPs), and T2 (addition of AgNO3). Physiological characteristics, anatomical analyses through microscopic structures, and metabolic profile studies were carried out to establish the effect of abiotic stress on these parameters in soybean plants. Analysis of the 1H NMR spectra revealed the presence of amino acids, organic acids, sugars, and polyphenols. The metabolic profiles of plants with AgNP and AgNO3 were qualitatively similar to the metabolic profile of the control group, suggesting that the application of silver does not affect secondary metabolites. From the PCA, it was possible to differentiate the three treatments applied, mainly based on the content of fatty acids, pinitol, choline, and betaine.

Green Synthesis and Characterization of Silver Nanoparticles Using Azadirachta indica Seeds Extract: In Vitro and In Vivo Evaluation of Anti-Diabetic Activity

BACKGROUND

Diabetes mellitus (DM) is a non-communicable, life-threatening syndrome that is present all over the world. The use of eco-friendly, cost-effective, and green-synthesised nanoparticles as a medicinal therapy in the treatment of DM is an attractive option.

OBJECTIVE

In the present study, silver nanoparticles (AI-AgNPs) were biosynthesized through the green synthesis method using Azadirachta indica seed extract to evaluate their anti-diabetic potentials.

METHODS

These nanoparticles were characterized by using UV-visible spectroscopy, Fourier transform infrared spectrophotometers (FTIR), scanning electron microscopy (SEM), DLS, and X-ray diffraction (XRD). The biosynthesized AI-AgNPs and crude extracts of Azadirachta indica seeds were evaluated for anti-diabetic potentials using glucose adsorption assays, glucose uptake by yeast cells assays, and alpha-amylase inhibitory assays.

RESULTS

Al-AgNPs showed the highest activity (75 ± 1.528%), while crude extract showed (63 ± 2.5%) glucose uptake by yeast at 80 µg/mL. In the glucose adsorption assay, the highest activity of Al-AgNPs was 10.65 ± 1.58%, while crude extract showed 8.32 ± 0.258% at 30 mM, whereas in the alpha-amylase assay, Al-AgNPs exhibited the maximum activity of 73.85 ± 1.114% and crude extract 65.85 ± 2.101% at 100 µg/mL. The assay results of AI-AgNPs and crude showed substantial dose-dependent activities. Further, anti-diabetic potentials were also investigated in streptozotocin-induced diabetic mice. Mice were administered with AI-AgNPs (10 to 40 mg/kg b.w) for 30 days.

CONCLUSIONS

The results showed a considerable drop in blood sugar levels, including pancreatic and liver cell regeneration, demonstrating that AI-AgNPs have strong anti-diabetic potential.

The Occurrence of Oxidative Stress Induced by Silver Nanoparticles in Chlorella vulgaris Depends on the Surface-Stabilizing Agent

Silver nanoparticles (AgNPs) are of great interest due to their antimicrobial properties, but their reactivity and toxicity pose a significant risk to aquatic ecosystems. In biological systems, AgNPs tend to aggregate and dissolve, so they are often stabilized by agents that affect their physicochemical properties. In this study, microalga Chlorella vulgaris was used as a model organism to evaluate the effects of AgNPs in aquatic habitats. Algae were exposed to AgNPs stabilized with citrate and cetyltrimethylammonium bromide (CTAB) agents and to AgNO₃ at concentrations that allowed 75% cell survival after 72 h. To investigate algal response, silver accumulation, ROS content, damage to biomolecules (lipids, proteins, and DNA), activity of antioxidant enzymes (APX, PPX, CAT, SOD), content of non-enzymatic antioxidants (proline and GSH), and changes in ultrastructure were analyzed. The results showed that all treatments induced oxidative stress and adversely affected algal cells. AgNO₃ resulted in the fastest death of algae compared to both AgNPs, but the extent of oxidative damage and antioxidant enzymatic defense was similar to AgNP-citrate. Furthermore, AgNP-CTAB showed the least toxic effect and caused the least oxidative damage. These results highlight the importance of surface-stabilizing agents in determining the phytotoxicity of AgNPs and the underlying mechanisms affecting aquatic organisms.

Effects of Silver Nanoparticles on Physiological and Proteomic Responses of Tobacco (Nicotiana tabacum) Seedlings Are Coating-Dependent

The harmful effects of silver nanoparticles (AgNPs) have been confirmed in many organisms, but the mechanism of their toxicity is not yet fully understood. In biological systems, AgNPs tend to aggregate and dissolve, so they are often stabilized by coatings that influence their physico-chemical properties. In this study, the effects of AgNPs with different coatings [polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB)] on oxidative stress appearance and proteome changes in tobacco (Nicotiana tabacum) seedlings have been examined. To discriminate between the nanoparticulate Ag form from the ionic one, the treatments with AgNO3, a source of Ag+ ions, were also included. Ag uptake and accumulation were found to be similarly effective upon exposure to all treatment types, although positively charged AgNP-CTAB showed less stability and a generally stronger impact on the investigated parameters in comparison with more stable and negatively charged AgNP-PVP and ionic silver (AgNO3). Both AgNP treatments induced reactive oxygen species (ROS) formation and increased the expression of proteins involved in antioxidant defense, confirming oxidative stress as an important mechanism of AgNP phytotoxicity. However, the mechanism of seedling responses differed depending on the type of AgNP used. The highest AgNP-CTAB concentration and CTAB coating resulted in increased H2O2 content and significant damage to lipids, proteins and DNA molecules, as well as a strong activation of antioxidant enzymes, especially CAT and APX. On the other hand, AgNP-PVP and AgNO3 treatments induced the nonenzymatic antioxidants by significantly increasing the proline and GSH content. Exposure to AgNP-CTAB also resulted in more noticeable changes in the expression of proteins belonging to the defense and stress response, carbohydrate and energy metabolism and storage protein categories in comparison to AgNP-PVP and AgNO3. Cysteine addition significantly reduced the effects of AgNP-PVP and AgNO3 for the majority of investigated parameters, indicating that AgNP-PVP toxicity mostly derives from released Ag+ ions. AgNP-CTAB effects, however, were not alleviated by cysteine addition, suggesting that their toxicity derives from the intrinsic properties of the nanoparticles and the coating itself.