Lytic transglycosylases such as Slt35 from E. coli are enzymes involved in bacterial cell wall remodelling and recycling, which represent potential targets for novel antibacterial agents. Here, we investigated a series of known glycosidase inhibitors for their ability to inhibit Slt35. While glycosidase inhibitors such as 1-deoxynojirimycin, castanospermine, thiamet G and miglitol had no effect, the phenothiazinium dye thionine acetate was found to be a weak inhibitor. IC50 values and binding constants for thionine acetate were similar for Slt35 and the hen egg white lysozyme. Molecular docking simulations suggest that thionine binds to the active site of both Slt35 and lysozyme, although it does not make direct interactions with the side-chain of the catalytic Asp and Glu residues as might be expected based on other inhibitors. Thionine acetate also increased the potency of the beta-lactam antibiotic ampicillin against a laboratory strain of E. coli.

Gold nanoparticles (AuNPs) have received considerable attention recently because of their chemical properties and potential applications in the medical field.Monodispersed AuNPs in this paper are successfully synthesized by using some stabilized ligands including 3,5-dinitrobenzoic acid (DNBA) and sodium acetate (SA) dispersible in aqueous media, where NaBH4 was used as a reducing agent to reduce KAuCl4 from Au (III) to Au (0).The synthesized AuNPs are characterized by using UV–Vis spectroscopy to evaluate their surface plasmon resonance (SPR) absorption in a wavelength range of 500–650 nm. The size and morphology of AuNPs were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), where the results displayed that AuNPs with a strong SPR peak around 530 nm and 536 nm with an average size of 10 ± 1.2 nm and 14.0 ± 0.9 nm at the initial time for both DNBA-AuNP and SA-AuNP respectively. The synthesized AuNPs illustrate perfect chemical stability for more than 24 weeks in an aqueous solution. Therefore, the size of DNBA-AuNP was smaller and most stable than SA-AuNP, which may be due to 2 nitro groups that have resonance with the benzene ring leading to an increase in the stability of AuNPs.The stability of AuNPs in this work was monitored at a range of pH 2-12. Where high stability was showed at pH 6.6 ± 0.5, while the aggregation appears at more than pH 10 and less than pH.3.5.Herein, in this paper AuNPs have shown remarkable results against multi-drug resistance Pseudomonas aeruginosa. AuNP functionalized by SA ligand is shown to have a greater biological effect and be more effective than DNBA-AuNP. Due to the high stability of AuNP prepared in this work, it can be further tested to be an improved choice for more biomedical applications in the future.

The micellar properties of the anionic surfactant, sodium dodecyl sulfate (SDS) are modified by the biologically active amino acids. Amino acids (AAs) have experienced a variety of interactions and are proposed to influence SDS micelles due to their nominated hydrophobic interactions. The present study determines the critical micellar concentration (CMC) of SDS in aqueous solutions as well as in amino aqueous solutions. Three amino acids (glutamic acid, histidine, and tryptophan) are considered here. The conductometric measurements were carried out using a wide range of SDS concentrations at different temperatures. Surface tension experiments have also been applied to estimate many surface parameters including surface excess concentration (Γmax), surface occupied area per surfactant molecule (Amin), surface tension at CMC (γcmc), surface pressure at CMC (Πcmc) and Gibbs free energy of adsorption (∆Gads°), enthalpy ∆Hm° and the critical packing parameter (CPP). Interestingly, CMC values of SDS in water and in aqueous amino acids estimated by the surface tension method are comparable with the corresponding values obtained by the conductance method. The thermodynamic parameters of SDS micellization were also evaluated in both presence and absence of AAs. The additives of AAs work to reduce the CMC values, as well as the SDS thermodynamic parameters. This reduction is highly dependent on the hydrophobicity of the AA side chain. Negative values of ∆Gm°, ∆Hm° elucidate that micellization of SDS in the presence of amino acids is thermodynamically spontaneous and exothermic. The outcomes here might be utilized for pharmaceutical applications to stabilize proteins and inhibit protein aggregation.

Silver nanoparticles (AgNPs) have been boosted in the medical field because of using suitable stabilized ligands leading to create specific shapes and sizes. AgNPs in this study are prepared in one-step using vitamin C (VC) and kojic acid (KA) as stabilized ligands in presence of sodium borohydride (NaBH4). As known, the Food and Drug Administration (FDA, USA) approved the use of KA for dermatological treatment purposes. Also, vitamin C as an antioxidant has reduced cancer diseases. The AgNPs are sufficiently stabilized by these biomolecules to remain dispersed in an aqueous solution for up to 12 weeks under room conditions. The AgNPs were characterized using UV-Visible absorption spectroscopy (UV-Vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), and attenuated Fourier transform infrared (ATR-FTIR). The produced AgNPs were spherical and monodispersed with a size diameter range of 11–15 nm based on the TEM results. The antibacterial activity of AgNPs was tested against Escherichia coli (E. coli) and Streptococcus aureus (S. aureus) at different concentrations (4 µg/ml, 8 µg/ml, 15 µg/ml, and 30 µg/ml). The finding results demonstrated that both these AgNPs significantly reduced bacteria growth, especially at the highest concentration of 30 µg/m. The VC-AgNP was highly active on the E. coli and S. aureus even at a lower concentration of 4 µg/ml. VC/or KA-AgNPs provided more encouraging results than when VC and KA were used alone, which would eventually allow VC dosages to be reduced in the future, which could be more effective against many diseases in the future.