Synthesis of silver nanoparticles using a modified Tollens’ method in conjunction with phytochemicals and assessment of their antimicrobial activity

Background: Silver nanoparticles (AgNPs) have attracted great attention due to their outstanding electrical, optical, magnetic, catalytic, and antimicrobial properties. However, there is a need for alternative production methods that use less toxic precursors and reduce their undesirable by-products. Phyto-extracts from the leaves of olive and rosemary plants can be used as reducing agents and (in conjunction with Tollens’ reagent) can even enhance AgNP antimicrobial activity. Methods: Conditions for the proposed hybrid synthesis method were optimized for olive leaf extracts (OLEs) and rosemary leaf extracts (RLEs). The resultant AgNPs were characterized using UV–visible spectroscopy, an environmental scanning electron microscope, and Dynamic Light Scattering analysis. An atomic absorption spectrophotometer was used to measure AgNP concentration. Fourier transform infrared spectroscopy (FTIR) was used to determine the specific functional groups responsible for the reduction of both silver nitrate and capping agents in the leaf extract. Additionally, the antimicrobial properties of the synthesized AgNPs were assessed against Gram-negative bacteria (Escherichia coli and Salmonella enterica) and Gram-positive bacteria (Staphylococcus aureus), by using both the Kirby–Bauer and broth microdilution methods on Mueller–Hinton (MH) agar plates. Results and Discussion: A simple, feasible, and rapid method has been successfully developed for silver nanoparticle synthesis by reducing Tollens’ reagent using leaf extracts from olive and rosemary plants (widely available in Jordan). Scanning electron microscopy images showed that the method produces AgNPs with a spherical shape and average core sizes of 45 ± 2 and 38 ± 3 nm for OLE and RLE, respectively. A negative zeta potential (ζ) of −43.15 ± 3.65 mV for OLE-AgNPs and −33.65 ± 2.88mV for RLE-AgNPs proved the stability of silver nanoparticles. FTIR spectra for AgNPs and leaf extracts indicated that the compounds present in the leaf extracts play an important role in the coating/capping of synthesized nanoparticles. The manufactured AgNPs exhibited an antibacterial effect against Escherichia coli and Staphylococcus aureus with minimum inhibitory concentrations (MIC) of 9.38 and 4.69 μl/ml for OLE-AgNPs and RLE-AgNPs, respectively. The MIC for Salmonella enterica were 18.75 μl/ml for both OLE-AgNPs and RLE-AgNPs. Furthermore, our results indicated that the RLE-AgNPs exhibited a stronger antibacterial effect than OLE-AgNPs against different bacteria species. These results contribute to the body of knowledge on nanoparticle production using plant-mediated synthesis and performance. They also offer insights into the potential for scaling up this production process for commercial implementation

Interplay of adiponectin and resistin in type 2 diabetes: Implications for insulin resistance and atherosclerosis

Aim: The study aims to investigate the association between type 2 diabetes and adipokines, particularly resistin and adiponectin, in insulin resistance. It also explores the potential of the resistin to adiponectin ratio as an indicator for these conditions Methods: This research involved 198 participants, including 100 patients with type 2 diabetes and 98 controls. It focused on measuring various biochemical parameters like HbA1c, fasting plasma glucose, lipid profiles (low-density lipoprotein, oxidized low-density lipoprotein, triglyceride, total cholesterol), and adipokines (resistin and adiponectin). The study utilized the Homeostasis Model Assessment of Insulin Resistance and Triglyceride-Glucose index to evaluate insulin resistance. Results: Type 2 diabetic patients exhibited higher levels of HbA1c, fasting plasma glucose, lipid profiles, and resistin, but lower adiponectin levels compared to controls. Adiponectin showed a negative correlation with insulin resistance, while resistin demonstrated a positive correlation. Both adipokines significantly related to atherogenic markers, with adiponectin offering protection against atherosclerosis and resistin augmenting it. Conclusion: The findings underscore the complex roles of resistin and adiponectin in the pathophysiology of type 2 diabetes, insulin resistance. The resistin to adiponectin ratio could be a useful biomarker for insulin resistance. These insights suggest potential therapeutic strategies for treating diabetes and preventing its complications