[Single-laboratory Validation of an Analytical Method for Detarmination of Fusarium toxins in Buckwheat and Job's Tears].

Fusarium species infect the major cereals consumed as food and feed, contaminating them with various toxic secondary metabolites known as toxins. Among these toxins, which include trichothecenes, zearalenone (ZEA), and fumonisins, the type-B trichothecene deoxynivalenol (DON) is generally considered as the most important. The present study evaluates an analytical method for the detection and quantification of multiple Fusarium toxins, namely, DON, acetyl forms of DON (3-Ac-DON and 15-Ac-DON), a glycoside form of DON (DON-3G), and other Fusarium toxins (nivalenol, an acetyl form of NIV (fusarenonX), T-2 and HT-2 toxins, diacetoxyscirpenol, and ZEA) in Job's tears and buckwheat.

Preferential solvation of meso-methyl BODIPYs with pyridine via pseudo-hydrogen-bonds.

This study explored unexpected pseudo-hydrogen bond interactions between meso-methyl BODIPYs and pyridine or acridine. NMR spectral evidence indicated that the meso-methyl group and BF2 core of BODIPYs formed C-H⋯N and C-H⋯F-B pseudo-hydrogen bonds with pyridine, respectively. The weak binding strength was attributed to the preferential solvation of pyridine in the vicinity of meso-methyl BODIPYs in cyclohexane. The observations were explained by the formation of pseudo-hydrogen bonds based on the quantum theory of atoms in molecules (QTAIM) formalism. In contrast, acridine binds to BODIPY with a moderate binding strength. QTAIM formalism suggested the existence of the complementary pseudo-hydrogen bonds, which superficially seemed to rationalise the experimental observations. However, extensive NMR experiments have found no discrete geometry for the complex, indicating considerable geometric freedom. This discrepancy suggests that the static pictures based on the QTAIM analyses conflict with the enthalpy-entropy compensation principle in essential thermodynamics.

Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene-Ethynylene-Linked Porphyrin Arrays.

To synthesize meso-ethynylene-conjugated porphyrin arrays, the Sonogashira cross-coupling reaction is straightforward to construct the C(sp)-C(sp2) bonds, but the reaction is often accompanied by side reactions such as the Glaser homocoupling. The rate-determining oxidative addition step results in the unexpected kinetic competition with the Glaser homocoupling, which is desired to be circumvented. We here propose two sets of improved strategies for the synthesis of arylene-ethynylene-linked porphyrin arrays from the meso-brominated porphyrin and alkynes. First, we explored the solvent-modulated approach employing dichloromethane as the reaction solvent to minimize the formation of the copper acetylide dimer as the intermediate for the Glaser homocoupling, while the scope of the approach is limited. Subsequently, we have developed the trimethylsilanolate-promoted Hiyama-type approach that activates alkynyl trimethylsilanes (TMSs) by use of potassium trimethylsilanolate under amine-free conditions. The latter approach is advantageous not only in skipping the preprotodesilylation of the TMS group but also in achieving an excellent isolated yield.

Evidence of C-F···H-C Attractive Interaction: Enforced Coplanarity of a Tetrafluorophenylene-Ethynylene-Linked Porphyrin Dimer.

The formation of C-F···H-C "hydrogen bonds" has been a controversial subject because, in principle, fluorine is hardly an acceptor for less acidic protons contrasting to the C-F···H-O and C-F···H-N hydrogen bonds. Nevertheless, the interaction is emerging as a powerful implement for confining the torsional rotation in the design of fully coplanar π-conjugated polymers. Heretofore, no evidence of the C-F···H-C interaction has been observed in solutions. We herein disclose comprehensive evidence that the C-F···H-C interaction produces an attractive force. A 19F-1H heteronuclear Overhauser effect experiment elucidated the close proximity of the F and H atoms in the doubly edge-facing C-F···H-C interactions of a meso-tetrafluorophenylene-ethynylene-conjugated porphyrin dimer (1). Extensive electronic and photophysical property investigations confirmed that all the aromatic units were torsionally restricted by the C-F···H-C interactions. Moreover, the enforced coplanarity invoked a markedly high π-staking propensity. Thus, we have firmly established the formation of a C-F···H-C interaction that produces a hydrogen-bond-like attractive force in solution.

Ellagitannins from Rosa roxburghii suppress poly(I:C)-induced IL-8 production in human keratinocytes.

The anti-inflammatory effects of a 50% aqueous extract of Rosa roxburghii fruit (RRFE) and two ellagitannins (strictinin and casuarictin) isolated from the RRFE were evaluated in a cell model of skin inflammation induced by self-RNA released from epidermal cells damaged by UV ray (UVR) irradiation. The RRFE inhibited interleukin-8 (IL-8) mRNA expression in normal human epidermal keratinocytes (NHEKs) stimulated with polyinosinic:polycytidylic acid (poly(I:C)), a ligand of toll-like receptor-3 (TLR-3). The plant-derived anti-inflammatory agents, dipotassium glycyrrhizinate (GK2) and allantoin, had no influence on the IL-8 expression. The purified compounds, strictinin and casuarictin, inhibited the IL-8 mRNA expression and IL-8 release induced in NHEKs by poly(I:C). These ellagitannins were thus found to be responsible for the biological activity exhibited by the RRFE. This study demonstrates that RRFE and isolated RRFE compounds show promise as ingredients for products formulated to improve skin disorders induced by UVR irradiation.

Role of tyrosine kinase-independent phosphorylation of EGFR with activating mutation in cisplatin-treated lung cancer cells.

Epidermal growth factor receptor (EGFR) mutation is one of the hallmarks of cancer progression and resistance to anticancer therapies, particularly non-small cell lung carcinomas (NSCLCs). In contrast to the canonical EGFR activation in which tyrosine residues are engaged, we have demonstrated that the non-canonical pathway is triggered by phosphorylation of serine and threonine residues through p38 and ERK MAPKs, respectively. The purpose of this study is to investigate the role of non-canonical EGFR pathway in resistance mechanism against cisplatin treatment. Wild type and mutated (exon 19 deletion) EGFR-expressing cells responded similarly to cisplatin by showing MAPK-mediated EGFR phosphorylation. It is interesting that internalization mechanism of EGFR was switched from tyrosine kinase-dependent to p38-dependent fashions, which is involved in a survival pathway that counteracts cisplatin treatment. We therefore introduce a potential combinatorial therapy composed of p38 inhibition and cisplatin to block the activation of EGFR, therefore inducing cancer cell death and apoptosis.

Inverse correlation between Thr-669 and constitutive tyrosine phosphorylation in the asymmetric epidermal growth factor receptor dimer conformation.

We have recently identified tumor necrosis factor (TNF)-α-induced phosphorylation of epidermal growth factor receptor (EGFR) at Thr-669 and Ser-1046/1047 via ERK and p38 pathways, respectively. In the present study, we investigated the roles of ligand-induced phosphorylation of serine and threonine residues in EGFR-overexpressing MDA-MB-468 breast cancer cells. Epidermal growth factor and heregulin, an ErbB3 ligand, induced the phosphorylation of Thr-669 and Ser-1046/1047. Inversely, constitutive tyrosine phosphorylation of the C-terminal domain, including Tyr-1068, was significantly downregulated on ligand stimulation. Inhibition of the ERK pathway by U0126 blocked ligand-induced Thr-669 phosphorylation as well as Tyr-1068 dephosphorylation. Downregulation of constitutive tyrosine phosphorylation of EGFR in HEK293 cells stably expressing the wild type was abolished by substitution of Thr-669 for Ala. In an asymmetric EGFR homodimer structure, one Thr-669 in the receiver kinase of the dimer was involved in downregulation. Similarly, Thr-669 in an EGFR-ErbB3 heterodimer also participated in tyrosine dephosphorylation. These results indicate that ERK-mediated Thr-669 phosphorylation suppresses constitutive tyrosine phosphosphorylation in the homo- and heterodimer asymmetric conformations of the EGFR.

TAK1-mediated serine/threonine phosphorylation of epidermal growth factor receptor via p38/extracellular signal-regulated kinase: NF-{kappa}B-independent survival pathways in tumor necrosis factor alpha signaling.

The kinase TAK1, a mitogen-activated protein kinase kinase kinase (MAP3K), has been widely accepted as a key kinase activating NF-kappaB and MAPKs in tumor necrosis factor alpha (TNF-alpha) signaling. We have recently reported that TAK1 regulates the transient phosphorylation and endocytosis of epidermal growth factor receptor (EGFR) in a tyrosine kinase activity-independent manner. In the present study, we found that Thr-669 in the juxtamembrane domain and Ser-1046/1047 in the carboxyl-terminal regulatory domain were transiently phosphorylated in response to TNF-alpha. Experiments using chemical inhibitors and small interfering RNA demonstrated that TNF-alpha-mediated phosphorylation of Thr-669 and Ser-1046/7 were differently regulated via TAK1-extracellular signal-regulated kinase (ERK) and TAK1-p38 pathways, respectively. In addition, p38, but not ERK, was involved in the endocytosis of EGFR. Surprisingly, modified EGFR was essential to prevent apoptotic cellular responses; however, the EGFR pathway was independent of the NF-kappaB antiapoptotic pathway. These results demonstrated that TAK1 controls two different signaling pathways, IkappaB kinase-NF-kappaB and MAPK-EGFR, leading to the survival of cells exposed to the death signal from the TNF-alpha receptor.