Anticancer Activity of 2-O-caffeoyl Alphitolic Acid Extracted from the Lichen,Usnea barbata 2017-KL-10

Colorectal cancer is one of the life-threatening ailments causing high mortality and morbidity worldwide. Despite the innovation in medical genetics, the prognosis for metastatic colorectal cancer in patients remains unsatisfactory. Recently, lichens have attracted the attention of researchers in the search for targets to fight against cancer. Lichens are considered mines of thousands of metabolites. Researchers have reported that lichen-derived metabolites demonstrated biological effects, such as anticancer, antiviral, anti-inflammatory, antibacterial, analgesic, antipyretic, antiproliferative, and cytotoxic, on various cell lines. However, the exploration of the biological activities of lichens’ metabolites is limited. Thus, the main objective of our study was to evaluate the anticancer effect of secondary metabolites isolated from lichen (Usnea barbata 2017-KL-10) on the human colorectal cancer cell line HCT116. In this study, 2OCAA exhibited concentration-dependent anticancer activities by suppressing antiapoptotic genes, such as MCL-1, and inducing apoptotic genes, such as BAX, TP53, and CDKN1A(p21). Moreover, 2OCAA inhibited the migration and invasion of colorectal cancer cells in a concentration-dependent manner. Taken together, these data suggest that 2OCAA is a better therapeutic candidate for colorectal cancer.     

Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) were fabricated using TiO₂ nanoparticles (NPs), TiO₂ nanotube arrays (NTAs), and surface-modified NTAs with a TiCl₄ treatment. The photovoltaic efficiencies of the DSSCs using TiO₂ NP, NTA, and TiCl₄-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl₄-treated TiO₂ NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge–transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO₂ NTAs contributes to the smaller charge–transfer resistance, resulting in a higher short circuit current (J _sc), even at lower dye adsorption. Furthermore, the TiCl₄-treated NTAs showed even smaller charge–transfer resistance, resulting in the highest J _sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl₄-treated TiO₂ electrodes.     

A rational invariant for knot crossings

A rational number-valued invariant is constructed for the crossings of knot projections. The invariant completely determines the signature and (signed) determinant of the knot obtained by changing the crossing. In particular, if the invariant is not 0, then the new knot is distinct from the old one.

     

Novel Variable PDL Emulator Based on LiNbO3 Modulator

We propose and demonstrate a novel variable PDL emulator based on a LiNbO3 modulator. The proposed emulator could vary the PDL values simply by adjusting the bias voltage of modulator. The results show that the proposed PDL emulator could generate a wide range of PDL values (0 ～ 35 dB). The generated PDL value could be maintained within ± 0.02 dB for ＞70 minutes. The wavelength dependency was about 0.03 dB in the range of 1520nm ～ 1590 nm.     

A method for image quality evaluation considering adaptation to luminance of surround and noise in stimuli

This study intends to quantify the effects of the surround luminance and noise of a given stimulus on the shape of spatial luminance contrast sensitivity function (CSF) and to propose an adaptive image quality evaluation method. The proposed image evaluation method extends a model called square-root integral (SQRI). The non-linear behaviour of the human visual system was taken into account by using CSF. This model can be defined as the square root integration of multiplication between display modulation transfer function and CSF. The CSF term in the original SQRI was replaced by the surround adaptive CSF quantified in this study and it is divided by the Fourier transform of a given stimulus for compensating for the noise adaptation.     

CIECAM02-UCS based evaluation of colorimetric characterization modeling for a liquid crystal display using a digital still camera

A method for characterizing a liquid crystal display (LCD) was developed using a characterized digital still camera (DSC). Prediction accuracy of the method was evaluated through calculating the Euclidean distance between prediction and the corresponding reference in the most lately standardized color appearance model CIECAM02 with rescaled lightness. This paper describes a framework for obtaining a device-independent representation of displayed colors on the monitor with a less time-consuming method for accurate characterization. A DSC was first characterized using a polynomial model and then an LCD was characterized using two instruments: a tele-spectroradiometer and the characterized DSC. In total, five characterization methods were tested of which PLCC predicted the results most accurately.     

Crystal structures and catalytic mechanism of the Arabidopsis cinnamyl alcohol dehydrogenases AtCAD5 and AtCAD4

The cinnamyl alcohol dehydrogenase (CAD) multigene family in planta encodes proteins catalyzing the reductions of various phenylpropenyl aldehyde derivatives in a substrate versatile manner, and whose metabolic products are the precursors of structural lignins, health-related lignans, and various other metabolites. In Arabidopsis thaliana, the two isoforms, AtCAD5 and AtCAD4, are the catalytically most active being viewed as mainly involved in the formation of guaiacyl/syringyl lignins. In this study, we determined the crystal structures of AtCAD5 in the apo-form and as a binary complex with NADP+, respectively, and modeled that of AtCAD4. Both AtCAD5 and AtCAD4 are dimers with two zinc ions per subunit and belong to the Zn-dependent medium chain dehydrogenase/reductase (MDR) superfamily, on the basis of their overall 2-domain structures and distribution of secondary structural elements. The catalytic Zn2+ ions in both enzymes are tetrahedrally coordinated, but differ from those in horse liver alcohol dehydrogenase since the carboxyl side-chain of Glu70 is ligated to Zn2+ instead of water. Using AtCAD5, site-directed mutagenesis of Glu70 to alanine resulted in loss of catalytic activity, thereby indicating that perturbation of the Zn2+ coordination was sufficient to abolish catalytic activity. The substrate-binding pockets of both AtCAD5 and AtCAD4 were also examined, and found to be significantly different and smaller compared to that of a putative aspen sinapyl alcohol dehydrogenase (SAD) and a putative yeast CAD. While the physiological roles of the aspen SAD and the yeast CAD are uncertain, they nevertheless have a high similarity in the overall 3D structures to AtCAD5 and 4. With the bona fide CAD's from various species, nine out of the twelve residues which constitute the proposed substrate-binding pocket were, however, conserved. This is provisionally considered as indicative of a characteristic fingerprint for the CAD family.     

Secoisolariciresinol dehydrogenase: mode of catalysis and stereospecificity of hydride transfer in Podophyllum peltatum

Secoisolariciresinol dehydrogenase (SDH) catalyzes the NAD+ dependent enantiospecific conversion of secoisolariciresinol into matairesinol. In Podophyllum species, (-)-matairesinol is metabolized into the antiviral compound, podophyllotoxin, which can be semi-synthetically converted into the anticancer agents, etoposide, teniposide and Etopophos. Matairesinol is also a precursor of the cancer-preventative "mammalian" lignan, enterolactone, formed in the gut following ingestion of, for example, various high fiber dietary foods, as well as being an intermediate to numerous defense compounds in vascular plants. This study investigated the mode of enantiospecific Podophyllum SDH catalysis, the order of binding, and the stereospecificity of hydride abstraction/transfer from secoisolariciresinol to NAD+. SDH contains a highly conserved catalytic triad (Ser153, Tyr167 and Lys171), whose activity was abolished with site-directed mutagenesis of Tyr167Ala and Lys171Ala, whereas mutagenesis of Ser153Ala only resulted in a much reduced catalytic activity. Isothermal titration calorimetry measurements indicated that NAD+ binds first followed by the substrate, (-)-secoisolariciresinol. Additionally, for hydride transfer, the incoming hydride abstracted from the substrate takes up the pro-S position in the NADH formed. Taken together, a catalytic mechanism for the overall enantiospecific conversion of (-)-secoisolariciresinol into (-)-matairesinol is proposed.