Elemental selenium, an essential element for humans and animals is totally obtained from foods and used for the synthesis of selenoproteins, such as glutathione peroxidases (GPx). Fish and shellfish are selenium-rich foodstuffs, and are the major dietary source of selenium for the Japanese population. However, the chemical structure and bioavailability of selenium species from seafood materials have hardly been elucidated. The Japanese littleneck clam (Asari) is the most popular consumed seawater bivalve in Japan. In this study, the selenium species in Asari were separated and assessed as a nutritional selenium source using cultured cells. The selenium content in the lyophilized Asari edible meat was 4.34±0.49 μg/g. The selenium extraction rate into water was 17−24% (1.07±0.14 μg/g-dry Asari). Based on the results that selenium in the Asari water-extract was mostly retained on both cationic Q Sepharose and anionic SP Sepharose columns, the selenium species in the Asari water-extract appeared to possess an amphoteric character. Selenium in the Asari water-extract mostly passed through a membrane with the molecular mass cutoff of 5000. After lyophilization, the resulting filtrate was subjected to in vitro assessment of the selenium bioavailability. HepG2 and HeLa cells were cultured in a basal medium containing the filtrate. The selenium content and GPx activity of the HepG2 cells increased with the increasing selenium content in the medium and incubation time, which suggested that the selenium species in the Asari water-extract were utilized for the synthesis of the GPxs. Overall, these results demonstrated that Asari contains nutritionally effective selenium species.

Staphylococcal superantigen-like 10 (SSL10) is one of the immunoglobulin G (IgG) binding proteins produced by Staphylococcus aureus (S. aureus). SSL10 is reported to bind to Fc region of human IgG and interfere its effector functions. As SSL10 shows no homology with other staphylococcal IgG binding proteins, the mechanism of interaction between SSL10 and IgG remains to clear. In this study we attempted to identify the regions of SSL10 that are responsible for binding to human IgG (hIgG) by analyzing the binding ability of chimeras between SSL10 and its paralog, SSL7. The chimeras that retained either β1-β3 or β10-β12 of SSL10 bound to immobilized hIgG. On the other hand, chimeras that lacked both of these regions did not show binding activity to hIgG. In far western analysis, biotinylated hIgG interacted with SSL10 and chimera that retained β1-β3 and β10-β12 of SSL10. Collectively, SSL10 has two responsible regions for binding to hIgG, one is located in N-terminal half of oligonucleotide/oligosaccharide-binding (OB)-fold domain and the other is in C-terminal half of β-grasp domain. These findings would contribute to understand the mechanism of immune evasion of S. aureus and also to develop vaccines and drugs against S. aureus.

Stemona alkaloids such as (±)-stemonamine/ (±)-isostemonamine, have a unique structure, possibly coupled with potential biological activities. The establishment of effective total synthesis protocols for stemonamine alkaloids has been a challenge for synthetic chemists so far. These stemonamine alkaloids are isolated as racemates and there is no report concerning their asymmetric total synthesis. It is generally understood that any pair of enantiomers have physically and chemically indistinguishable properties. However, stereochemistry is a critical point in biological systems because most biological reactions, such as those mediated by enzymes and receptors, are stereospecific. We have successfully established the methods of asymmetric total synthesis of the stemonamine alkaloids, (–)-stemonamine/(–)-isostemonamine. We studied the potential application of these Stemona alkaloids as anti-proliferative agents. Experiments were conducted by using two representative human breast cancer cell lines, MCF-7 and MDA-MB-231, and our results indicated that i) (–)-isostemonamine displays strong cytotoxic effects on the highly aggressive estrogen receptor α (ERα)-negative MDA-MB-231 cell line, but not on the ERα-positive MCF-7 cells, with an IC₅₀ value (9.3 ± 1.9 μM), which is comparable to that of etoposide (IC₅₀ = 7.1 μM ± 1.4 μM), and ii) the thioamide derivative of (–)-isostemonamine does not suppress the growth of MDAMB-231 cells.

We prepared virgin (Lig) and calcined lignin at 200–1000 °C (Lig200, Lig400, Lig600, Lig800, and Lig1000) and evaluated their adsorption capability for zinc ions from the water phase. The properties (morphology, specific surface area, pore volume, mean pore diameter, and functional groups) of adsorbents were characterized by scanning electron microscopy, specific surface area analysis, and FT-IR analysis. The specific surface area and pore volume of Lig800 was greater than those of the other adsorbents. In addition, -OH and -COOH groups were detected on Lig, Lig200, and Lig400, but those functional groups were not confirmed by calcination treatment over 600 °C. Amount of zinc ions adsorbed on Lig800 was greater than that on other adsorbents. We also evaluated the adsorption mechanism of zinc ions with adsorbents. The result showed that the amount of zinc ions adsorbed was related to ion-exchange with proton (correlation coefficient: 0.817) or physical property (mesopore volume; correlation coefficient: 0.867) for Lig, Lig200, and Lig400 or Lig600, Lig800, and Lig1000, respectively. These results indicate that the adsorption mechanism is changed with calcination treatment. Moreover, we elucidated the effect of temperature on the adsorption of zinc ions, and evaluated the adsorbent surface before and after zinc ion adsorption. We confirmed the zinc existed on the adsorbent surface after adsorption. Finally, as per the thermodynamic parameters, the negative value of ΔG indicates the spontaneous nature and feasibility of the zinc ion adsorption. These findings provide significant information that can be useful for removal of zinc ions from aqueous solution.

Several metal(loid) toxicants can trigger cytotoxicity by causing apoptosis. Our previous study demonstrated that cadmium induces apoptosis by suppressing expression of the apoptosis inhibitor, BIRC3 [Baculoviral inhibition of apoptosis (IAP) protein repeat containing 3], in human proximal tubular cells (HK-2 cells). BIRC3 is a member of the BIRC family, which consists of eight family members in human, and seven in mouse. The observed suppression of BIRC3 gene expression was mostly specific to cadmium and to HK-2 cells. In this study, we examined whether methylmercury, inorganic mercury, or arsenic may affect the gene expression of other BIRC family members in several different cultured cells. Methylmercury decreased the level of BIRC2 mRNA and increased the level of BIRC5 mRNA in human IMR-32 neuroblastoma cells. Methylmercury increased the mRNA levels of BIRC2, BIRC5, and BIRC8 and decreased the mRNA levels of BIRC6 in HK-2 cells. Inorganic mercury increased the mRNA levels of BIRC2 and BIRC5 in HK-2 cells. Finally, arsenic increased the levels of Birc1 and Birc7 and decreased the levels of Birc2, Birc4, Birc5, and Birc6 mRNA in mouse normal hepatic AML-12 cells. Taken together, these results indicate that each metal(loid) toxicant may regulate the gene expression of BIRC family members in different manners. Therefore, each BIRC family member may play distinct roles when various tissues are exposed to toxic heavy metals or metalloid toxicants.

The nuclear receptor pregnane X receptor (PXR, NR1I2) regulates several liver functions such as xenobiotic metabolism, energy metabolism, inflammation or cell growth, which are associated with drug-drug interactions and some diseases. It is well known that there are large species differences between human PXR and mouse PXR (mPXR) ligands. Although mouse models are often used in biological research, the number of mPXR ligands are limited. In the present study, we have thus searched mPXR activators from 190 industrial chemicals and 161 agricultural chemicals by reporter assay system with a promoter region of PXR target gene, and mouse primary hepatocytes and mice were treated with the candidates to confirm mPXR activation. Thirty-eight chemicals were selected after reporter assay screening. Among them, seven chemicals were selected as potential mPXR activators since their treatment increased mRNA levels of Cyp3a11, a representative PXR target gene, in mouse primary hepatocytes. Finally, in in vivo experiments using mice, hepatic Cyp3a11 mRNA levels were induced by treatment with flusilazole and metconazole. These results suggest that these two chemicals function as mPXR activators in vitro and in vivo.

Vancomycin (VCM), a glycopeptide antibiotic, is commonly applied to infectious diseases caused by Grampositive bacteria, in particular including methicillin-resistant Staphylococcus aureus (MRSA). However, VCM treatment sometimes causes adverse side effects, such as nephropathy and deafness. Although both side effects have been implicated in inflammatory processes, the underlying mechanisms remain unknown. Here, we investigate the cellular responses induced by VCM, especially focusing on the inflammatory responses, and found that VCM promotes the gene expression of NOD-like receptor (NLR) and absent in melanoma 2 (AIM2)-like receptor (ALR) families that mediate release of pro-inflammatory cytokines, interleukin-1β (IL-1β) and IL-18, by forming the multiprotein complexes, called inflammasomes. Thus, our findings suggest that VCM promotes IL-1β- and IL-18-mediated inflammation through the upregulation of the components of inflammasomes, which provides insight into the VCM-induced inflammation-related side effects.

Methylmercury is a major environmental pollutant that exhibits neurotoxicity. We previously reported that proteolytic systems such as the ubiquitin–proteasome system (UPS) and autophagy are involved in methylmercury toxicity. It is known that the intercellular level of PTEN, a phosphatase involved in autophagy inhibition, is regulated by the UPS. In this study, we coincidentally found that the PTEN level was decreased by methylmercury in the lysate solubilized with RIPA buffer containing 0.1% sodium dodecyl sulfate (SDS). However, the decrease in PTEN level caused by methylmercury was scarcely observed in RIPA buffer containing 2% SDS. These results suggest that methylmercury lowers the solubility of PTEN protein. Moreover, phosphorylation of Akt, a protein kinase that is negatively controlled via PTEN, was accelerated in accordance with a decrease in PTEN protein solubility. This suggests that methylmercury may inhibit PTEN activity by decreasing its solubility. Moreover, PTEN overexpression confers resistance to methylmercury in SH-SY5Y neuroblastoma cells. These results suggest that PTEN is a novel factor involved in reducing methylmercury toxicity and that methylmercury inhibits PTEN activity by decreasing the solubility of PTEN protein, thereby increasing cytotoxicity.