Lignans, flavonoids and coumarins from <i>Viola philippica</i> and their α-glucosidase and HCV protease inhibitory activities

<p>Two lignans including a new one, five flavonoids and five coumarins were isolated from the whole plant of <i>Viola philippica</i> (synonymised as <i>Viola yedoensis</i> Makino). The new compound was structurally determined as (7<i>R</i>,8<i>S</i>,8′<i>S</i>) -3,3′-dimethoxy- 4,4′,9-trihydroxy- 7,9′-epoxy-8,8′-lignan 9-O-rutinoside by analysis of its NMR, MS and CD spectroscopic data. The known compounds were characterised by comparing their NMR and MS data with those reported. Among the known compounds, 5-hydroxy-4′-methoxyflavone-7-O- rutinoside, 6,7-di-O-β-D- glucopyranosylesculetin, and 7<i>R</i>,8<i>S</i>-dihydrodehydrodiconiferyl alcohol 4-O-β-D- glucopyranoside were isolated and identified from this genus for the first time. Of these compounds, 5-hydroxy-4′-methoxyflavone-7-O-rutinoside and (7<i>R</i>,8<i>S</i>,8′<i>S</i>) -3,3′-dimethoxy- 4,4′,9-trihydroxy- 7,9′-epoxy-8,8′-lignan 9-O-rutinoside were potently active against α-glucosidase, while the two dimeric coumarins, 5, 5′-bi (6, 7-dihydroxycoumarin) and 6,6′,7,7′-tetrahydroxy-5,8′-bicoumarin potently inhibited HCV protease.</p

Anion-Induced Supramolecular Isomerism in Two Preyssler P₅W₃₀ Polyoxometalate-Based Hybrid Materials

Two extended Preyssler P₅W₃₀ polyoxometalate-based inorganic–organic hybrid materials exhibiting anion-induced supramolecular isomerism were reported. Because of the <i>cis</i>–<i>trans</i> isomerism in the octahedral CoN₂O₄ coordination geometry, the Preyssler P₅W₃₀ polyoxometalates are extended by double O–Co–O bridges in <b>1α</b> and a single O–Co–O bridge in <b>1β</b> to form the isomeric 2D 4-connected 4⁴-<b>sql</b> and 3D 8-connected <b>bcu</b> networks, respectively. Both compounds show electrocatalytic abilities on the reduction of H₂O₂

Regorafenib inhibited gastric cancer cells growth and invasion via CXCR4 activated Wnt pathway

<div><p>Aim</p><p>Regorafenib is an oral small-molecule multi kinase inhibitor. Recently, several clinical trials have revealed that regorafenib has an anti-tumor activity in gastric cancer. However, only part of patients benefit from regorafenib, and the mechanisms of regorafenib’s anti-tumor effect need further demonstrating. In this study, we would assess the potential anti-tumor effects and the underlying mechanisms of regorafenib in gastric cancer cells, and explore novel biomarkers for patients selecting of regorafenib.</p><p>Methods</p><p>The anti-tumor effects of regorafenib on gastric cancer cells were analyzed via cell proliferation and invasion. The underlying mechanisms were demonstrated using molecular biology techniques.</p><p>Results</p><p>We found that regorafenib inhibited cell proliferation and invasion at the concentration of 20μmol/L and in a dose dependent manner. The anti-tumor effects of regorafenib related to the decreased expression of CXCR4, and elevated expression and activation of CXCR4 could reverse the inhibition effect of regorafenib on gastric cancer cells. Further studies revealed that regorafenib reduced the transcriptional activity of Wnt/β-Catenin pathway and led to decreased expression of Wnt pathway target genes, while overexpression and activation of CXCR4 could attenuate the inhibition effect of regorafenib on Wnt/β-Catenin pathway.</p><p>Conclusions</p><p>Our findings demonstrated that regorafenib effectively inhibited cell proliferation and invasion of gastric cancer cells via decreasing the expression of CXCR4 and further reducing the transcriptional activity of Wnt/β-Catenin pathway.</p></div

The inhibitory effect of regorafenib on the invasion of gastric cancer cells.

<p>The invasion of SGC-7901, MKN-28, and MKN-45 cells were determined as described in Materials and Methods. Representative tumor cell invaded were photographed (A) in a comparison of the control groups (B, *, <i>P</i><0.05).</p

Regorafenib inhibited Wnt/β-catenin pathway via CXCR4.

<p>A. The activity of TOP and FOP flash were analyzed in gastric cancer cells treated with regorafenib and CXCR4 overexpression. B. Real-time PCR showed that the expression of Wnt target genes such as <i>CTNNB1</i>, <i>CD44</i>, <i>CD31</i> and <i>CCND1</i> were increase in gastric cancer cells with CXCR4 overexpression, whereas decreased in gastric cancer cells treated with regorafenib at the concentration of 20μmol/L as compared to the control.</p

The inhibitory effect of regorafenib on the growth of gastric cancer cells.

<p>Cell lines SGC7901(A), MKN-28(B) and MKN-45(C) were seeded in 96-well plates. Cytotoxicity of regorafenib was assessed using MTT test at day1, day 2, day 3, day 4 and day 5 of different concentration groups. All assays were performed in triplicate. D and E, the cell colonies were significantly reduced in regorafenib groups (20μmol/L) in soft agar assay (<i>P</i><0.05).</p

Evidence for Biotrophic Lifestyle and Biocontrol Potential of Dark Septate Endophyte <i>Harpophora oryzae</i> to Rice Blast Disease

<div><p>The mutualism pattern of the dark septate endophyte (DSE) <i>Harpophora oryzae</i> in rice roots and its biocontrol potential in rice blast disease caused by <i>Magnaporthe oryzae</i> were investigated. Fluorescent protein-expressing <i>H. oryzae</i> was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. <i>H. oryzae</i> adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of <i>H. oryzae</i> was visualized by inoculation with eGFP-tagged <i>M. oryzae</i> in rice. <i>H. oryzae</i> protected rice from <i>M. oryzae</i> root invasion by the accumulation of H₂O₂ and elevated antioxidative capacity. <i>H. oryzae</i> also induced systemic resistance against rice blast. This systemic resistance was mediated by the <i>OsWRKY45</i>-dependent salicylic acid (SA) signaling pathway, as indicated by the strongly upregulated expression of <i>OsWRKY45</i>. The colonization pattern of <i>H. oryzae</i> was consistent with the typical characteristics of DSEs. <i>H. oryzae</i> enhanced local resistance by reactive oxygen species (ROS) and high antioxidative level and induced <i>OsWRKY45</i>-dependent SA-mediated systemic resistance against rice blast.</p></div

The activities of antioxidative system in <i>H. oryzae</i>-infected rice roots.

<p>Effects of <i>H. oryzae</i> on antioxidant activity in rice roots. The values are the means of three samples. Similar results were obtained in three independent experiments. Significance (Student’s <i>t</i>-test):</p>*<p>, <i>P</i><0.05;</p>**<p>, <i>P</i><0.01.</p

Relative amounts of fungal DNA in rice roots at different time points (1, 3, 5, 7, 10, 15, 20, 25 and 30 d.a.i.).

<p>A fungal colonization curve plotted with the means ± SD of six replicates is shown.</p

Vitality of <i>H. oryzae</i>-infected root cells as shown by staining with FM4-64 and DAPI, respectively.

<p>(a) The colonized cells became melanized lesions and showed enhanced fluorescence (arrows) from the intracellular hyphae at 10 d.a.i. (upper panels). Bars, 50 µm. Later (≥ 15 d.a.i.), additional hyphae penetrated the root cells and the lesion-like infected area became larger; moreover, the enhanced fluorescence and plant autofluorescence of some primary infected cells disappeared (arrowheads) (lower panels). Bars, 200 µm. (b) The internalization of FM4-64 into endomembrane structures in fungus-infected cells (arrowheads) and non-invaded cells (arrows) during early colonization (≤ 10 d.a.i.). Bars, 100 µm. (c) At 15 d.a.i., endocytosis disappeared in the cells occupied by microsclerotia (arrowhead), but remained in the adjacent non-infected cells (arrow). Bar, 50 µm. (d) Root segments stained with DAPI. A large number of DAPI-positive nuclei in root cells with slight infection at 5 d.a.i. (left panels; Bars, 400 µm). DAPI-stained nuclei in root cells occupied by abundant hyphae and microsclerotia at 15 d.a.i. (middle panels; Bars, 200 µm). DAPI-stained nuclei disappeared in root cells filled with microsclerotia, but remained in the adjacent non-invaded cells after 15 d.a.i. (right panels; Bars, 100 µm).</p