Protective Efficacy of Spilanthes acmella Murr. Extracts and Bioactive Constituents in Neuronal Cell Death.

Spilanthes acmella Murr., a well-known Thai traditional medicine, has been used for treatment of toothache, rheumatism, and fever. Diverse pharmacological activities of S. acmella Murr. have been reported. In this study, antioxidative and neuroprotective effects of S. acmella Murr. extracts as well as bioactive scopoletin, vanillic acid, and trans-ferulic acid found in the aerial parts of this plant species have been described. Protective effect of S. acmella Murr. extracts and bioactive compounds on dexamethasone-induced neuronal cell death was investigated. Different plant crude ethyl acetate (EtOAc) and methanol (MeOH) extracts including pure compounds of S. acmella Murr. were evaluated in human neuroblastoma SH-SY5Y cells. Cytotoxic effects were performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Mechanisms involved in the antioxidant effects of S. acmella Murr. regarding the activation of antioxidant marker proteins such as superoxide dismutase 2 (SOD2) and sirtuin 3 (SIRT3) were determined using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay, Western blot analysis, and immunocytochemistry. Dexamethasone significantly caused the decrease of SH-SY5Y cell viability. Conversely, the increases in reactive oxygen species (ROS), autophagy, and apoptosis were observed in dexamethasone-treated cells. S. acmella Murr. MeOH and EtOAc extracts, as well as the bioactive compounds, reversed the toxic effect of dexamethasone by increasing the cell viability, SIRT3 protein expression but reducing the ROS, autophagy, and apoptosis. This study demonstrated that S. acmella Murr. may exert its protective effects against ROS through SOD2 and SIRT3 signaling pathways in dexamethasone-induced neurotoxicity. S. acmella Murr. may be a candidate therapy for neuroprotection.

Synthesis, structural characterization, computational studies and stability evaluations of metal ions and ZnONPs complexes with dimercaptosuccinic acid.

Meso-2,3-dimercaptosuccinic acid (DMSA) is one of the efficient chelating reagents for treating the toxicity of several heavy metals. Currently, nanomaterial have been applied to various parts including zinc Oxide nanoparticles (ZnONPs). ZnONPs have several properties and are used as many applications. An increasing the amount of ZnONPs in commercial products causes risks related to free radicals or reactive oxygen species (ROS) in the body, leading to oxidative stress and eventually to the cancer process. In the present work, we mainly focused on the study of DMSA complexes in term of metal ions and nanoparticles. The synthesis of DMSA-ZnONPs by the co-precipitation method were determined, followed by Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy and UV-Vis spectrophotometry confirming successful synthesis process. The stability study of the DMSA complexes with metal ions and ZnONPs were determined and evaluated the stability constant (K), with the Benesi- Hildebrand equation. All complexes with DMSA were formed at a 1:2 ratio by the dithiol group and the carboxyl group with different stability constants. Therefore, these results can help of an understanding of the interaction and its behavior between DMSA with heavy metal ion and ZnONPs. In addition, the stable structure of DMSA and metal ion complexes were predicted using the B3LYP and the 6-31G (d,p) basis set which the most stable structure of meso-DMSA was 2R,3S conformation and the metal ions and DMSA complexes was complex 2a with the binding energy of -1553.46 kcal mol-1.

Neuroprotective effect of Spilanthes acmella Murr. on pesticide-induced neuronal cells death.

OBJECTIVE: To investigate protective effects of Spilanthes acmella (S. acmella) Murr. extracts against pesticide-induced neuronal cells death and to elucidate the underlying molecular mechanism in dopaminergic (SH-SY5Y) cells lines. METHODS: Cell viability of SH-SY5Y cells was studied by treating the cells with various concentration of pirimicarb for 24 h. Neuroprotective effect of S. acmella Murr. extracts was investigated by adding the plant extracts to the medium for 24 h prior to the incubation with 100 µM H2O2 or with pirimicarb for 24 h. Control-untreated cells were incubated with the culture medium. Cell viability was measured by MTT assay, calpain and calpastatin expressions were analyzed by Western blotting and immunocytochemistry. RESULTS: Pretreatment of SH-SY5Y cells with S. acmella Murr. extracts (1 µg/mL) for 24 h significantly increased the dopaminergic neurons in pirimicarb-induced neurotoxicity. In addition, pretreatment with the S. acmella Murr. extracts led to decreased calpain but increased calpastatin protein levels. CONCLUSION: S. acmella Murr. extracts exerted neuroprotective effect, via an alteration of calcium homeostasis, against pirimicarb induced neurotoxicity. The S. acmella Murr. might be a potential natural candidate with neuroprotective activity.

Interaction evaluation of silver and dithizone complexes using DFT calculations and NMR analysis.

Silver has distinct antibacterial properties and has been used as a component of commercial products with many applications. An increasing number of commercial products cause risks of silver effects for human and environment such as the symptoms of Argyria and the release of silver to the environment. Therefore, the detection of silver in the aquatic environment is important. The colorimetric chemosensor is designed by the basic of ligand interactions with metal ion, leading to the change of signals for the naked-eyes which is very useful method to this application. Dithizone ligand is considered as one of the effective chelating reagents for metal ions due to its high selectivity and sensitivity of a photochromic reaction for silver as well as the linear backbone of dithizone affords the rotation of various isomeric forms. The present study is focused on the conformation and interaction of dithizone with silver using density functional theory (DFT). The interaction parameters were determined in term of binding energy of complexes and the geometry optimization, frequency of the structures and calculation of binding energies using density functional approaches B3LYP and the 6-31G(d,p) basis set. Moreover, the interaction of silver-dithizone complexes was supported by UV-Vis spectroscopy, FT-IR spectrum that were simulated by using B3LYP/6-31G(d,p) and (1)H NMR spectra calculation using B3LYP/6-311+G(2d,p) method compared with the experimental data. The results showed the ion exchange interaction between hydrogen of dithizone and silver atom with minimized binding energies of silver-dithizone interaction. Therefore, the results can be the useful information for determination of complex interaction using the analysis of computer simulations.

Determination of silver nanoparticle release from antibacterial fabrics into artificial sweat.

Silver nanoparticles have been used in numerous commercial products, including textiles, to prevent bacterial growth. Meanwhile, there is increasing concern that exposure to these nanoparticles may cause potential adverse effects on humans as well as the environment. This study determined the quantity of silver released from commercially claimed nanosilver and laboratory-prepared silver coated fabrics into various formulations of artificial sweat, each made according to AATCC, ISO and EN standards. For each fabric sample, the initial amount of silver and the antibacterial properties against the model Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria on each fabric was investigated. The results showed that silver was not detected in some commercial fabrics. Furthermore, antibacterial properties of the fabrics varied, ranging from 0% to greater than 99%. After incubation of the fabrics in artificial sweat, silver was released from the different fabrics to varying extents, ranging from 0 mg/kg to about 322 mg/kg of fabric weight. The quantity of silver released from the different fabrics was likely to be dependent on the amount of silver coating, the fabric quality and the artificial sweat formulations including its pH. This study is the unprecedented report on the release of silver nanoparticles from antibacterial fabrics into artificial sweat. This information might be useful to evaluate the potential human risk associated with the use of textiles containing silver nanoparticles.

Effect of ligand structure on the pathways for iron release from human serum transferrin.

Rate constants for the removal of iron from N-terminal monoferric transferrin have been measured for a series of phosphate and phosphonocarboxylic acids in pH 7.4 0.1 M hepes buffer at 25 degrees C. The bidentate ligands pyrophosphate and phosphonoacetic acid (PAA) show a combination of saturation and first-order kinetics with respect to the ligand concentration. Similar results are observed following a single substitution at the 2-position of PAA to give 2-benzyl-PAA and phosphonosuccinic acid. In contrast, disubstitution at the 2-position to form 2,2-dibenzyl-PAA leads to a marked reduction in iron removal via the first-order pathway. Rate constants were also measured for tripolyphosphate and phosphonodiacetic acid, which are elongated versions of PP(i) and PAA. In both cases, this elongation completely eliminates the first-order component for iron release while having relatively little impact on the saturation pathway. The sensitivity of the first-order component to the structure of the ligand strongly indicates that this pathway involves the binding of the ligand to a specific site on the protein and cannot be attributed to changes in the overall ionic strength of the solution as the ligand concentration increases. It is proposed that this structural sensitivity reflects steric restrictions on the ability of the incoming ligand to substitute for the synergistic carbonate anion to form a relatively unstable Fe-ligand-Tf ternary intermediate, which then dissociates to FeL and apoTf.