Crystal structure of Pyrococcus furiosus PF2050, a member of the DUF2666 protein family

Pyrococcus furiosus PF2050 is an uncharacterized putative protein that contains two DUF2666 domains. Functional and structural studies of PF2050 have not previously been performed. In this study, we determined the crystal structure of PF2050. The structure of PF2050 showed that the two DUF2666 domains interact tightly, forming a globular structure. Each DUF2666 domain comprises an antiparallel β-sheet and an α-helical bundle. One side of the PF2050 structure has a positively charged basic cleft, which may have a DNA-binding function. Furthermore, we confirmed that PF2050 interacts with circular and linear dsDNA.     

The design, synthesis, and biological evaluation of potent receptor tyrosine kinase inhibitors

Variously substituted indolin-2-ones were synthesized and evaluated for activity against KDR, Flt-1, FGFR-1 and PDGFR. Extension at the 5-position of the oxindole ring with ethyl piperidine (compound 7i) proved to be the most beneficial for attaining both biochemical and cellular potencies. Further optimization of 7i to balance biochemical and cellular potencies with favorable ADME/ PK properties led to the identification of 8h, a compound with a clean CYP profile, acceptable pharmacokinetic and toxicity profiles, and robust efficacy in multiple xenograft tumor models.     

Synthesis of novel azo-resveratrol,azo-oxyresveratrol and their derivatives as potent tyrosinase inhibitors

Ten azo compounds including azo-resveratrol (5) and azo-oxyresveratrol (9) were synthesized using a modified Curtius rearrangement and diazotization followed by coupling reactions with various phenolic analogs. All synthesized compounds were evaluated for their mushroom tyrosinase inhibitory activity. Compounds 4 and 5 exhibited high tyrosinase inhibitory activity (56.25% and 72.75% at 50 μM, respectively). The results of mushroom tyrosinase inhibition assays indicate that the 4-hydroxyphenyl moiety is essential for high inhibition and that 3,5-dihydroxyphenyl and 3,5-dimethoxyphenyl derivatives are better for tyrosinase inhibition than 2,5-dimethoxyphenyl derivatives. Particularly, introduction of hydroxyl or methoxy group into the 4-hydroxyphenyl moiety diminished or significantly reduced mushroom tryosinase inhibition. Among the synthesized azo compounds, azo-resveratrol (5) showed the most potent mushroom tyrosinase inhibition with an IC₅₀ value of IC₅₀ = 36.28 ± 0.72 μM, comparable to that of resveratrol, a well-known tyrosinase inhibitor.     

Insecticidal and insect growth regulatory activities of secondary metabolites from entomopathogenic fungi,Lecanicillium attenuatum

Insect growth regulators (IGRs) are effective alternatives to chemical insecticides because of their specificity and low environmental toxicity. Entomopathogenic fungi are an important natural pathogen of insects and have been developed as biological control agents. They produce a wide range of secondary metabolites such as antibiotics, pesticides, growth-promoting or inhibiting compounds and insect attracting agents. In this study, to explore novel IGR substances from entomopathogenic fungi, culture extracts of 189 entomopathogenic fungi isolated from Korean soil samples were investigated for their juvenile hormone (JH)-based IGR activities. Whereas none of the culture extracts exhibited JH agonist (JHA) activity, 14 extracts showed high levels of JH antagonist (JHAN) activity. Among them, culture extract of JEF-145 strain, which was identified as Lecanicillium attenuatum, showed the highest insecticidal against Aedes albopictus and Plutella xylostella. At liquid culture condition, JHAN activity was observed in culture soup rather than mycelial cake, indicating that substances with JHAN activity are released from the JEF-145 strain during culture. Furthermore, while extract from solid cultured JEF-145 strain showed insecticidal activities against both A. albopictus and P. xylostella, that from liquid cultured fungi showed insecticidal activity only against A. albopictus, indicating that L. attenuatum JEF-145 strain produces different kinds of secondary metabolites with JHAN activity depending on culture conditions. These results suggested that JHAN substances derived from entomopathogenic fungi could be usefully exploited to develop novel eco-friendly IGR insecticides.     

Differential effects of secreted frizzled-related proteins (sFRPs) on osteoblastic differentiation of mouse mesenchymal cells and apoptosis of osteoblasts

Secreted frizzled-related proteins (sFRPs) are modulators of Wnt signaling. This study was undertaken for definitive assessment of contribution of different sFRPs in osteoblastic differentiation of mesenchymal progenitor cells and apoptosis of osteoblasts. Treatment of C3H10T1/2 cells with sFRP-2 at concentrations of 10, 50, and 100 nM and sFRP-4 at low concentrations (5 nM) significantly increased Wnt-3A-induced alkaline phosphatase (ALP) activities, whereas sFRP-1 or 3 did not. Retroviral transduction of the sFRP-2 but not other sFRPs also significantly enhanced ALP activity induced by β-glycerophosphate and ascorbic acid. Furthermore, transfection of all the sFRP expression vectors significantly increased β-catenin/TCF reporter activity and the effects were most prominent with sFRP-2 and -4. In osteoblast apoptosis assay, only sFRP-3 increased etoposide-induced apoptosis in MC3T3-E1 mouse osteoblasts. In conclusion, we found that different repertoires of sFRPs exert differential effects on osteoblastic differentiation of mouse mesenchymal cells and cellular apoptosis of mouse osteoblasts in vitro.     

Inhibitory effects of gallic acid and quercetin on UDP-glucose dehydrogenase activity

We have examined polyphenols as potential inhibitors of UDP-glucose dehydrogenase (UGDH) activity. Gallic acid and quercetin decreased specific activities of UGDH and inhibited the proliferation of MCF-7 human breast cancer cells. Western blot analysis showed that gallic acid and quercetin did not affect UGDH protein expression, suggesting that UGDH activity is inhibited by polyphenols at the post-translational level. Kinetics studies using human UGDH revealed that gallic acid was a non-competitive inhibitor with respect to UDP-glucose and NAD⁺. In contrast, quercetin showed a competitive inhibition and a mixed-type inhibition with respect to UDP-glucose and NAD⁺, respectively. These results indicate that gallic acid and quercetin are effective inhibitors of UGDH that exert strong antiproliferative activity in breast cancer cells.     

N-Alkoxysulfamide,N-hydroxysulfamide,and sulfamate analogues of methionyl and isoleucyl adenylates as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases

A series of sulfamate surrogates of methionyl and isoleucyl adenylate have been investigated as MetRS and IleRS inhibitors by modifications of the sulfamate linker and adenine moieties. The discovery of 2-iodo Ile-NHSO(2)-AMP (58) as a potent Escherichia coli IleRS inhibitor revealed that a significant hydrophobic interaction between the 2-substituent of Ile-NHSO(2)-AMP and the adenine binding site of IleRS provided its high potency to the enzyme.     

A hybrid peptide derived from cecropin-A and magainin-2 inhibits osteoclast differentiation

The adult skeleton is in a dynamic state, being continually broken down and reformed by the coordinated actions of osteoclasts and osteoblasts. Increased osteoclast activity may contribute to the development of osteoporosis. Therefore, the intervention of osteoclast-mediated bone resorption is considered as an effective therapeutic approach in the treatment of osteoporosis. In the course of searching for agents that inhibit osteoclast differentiation and activation, we found that a novel hybrid peptide P1 derived from cecropin-A and magainin-2 reduced osteoclast differentiation in various osteoclast culture systems. As this peptide had no cytotoxicity on various cultures of primary cells and established cell lines, its inhibitory effect on osteoclastogenesis was not due to general cytotoxicity. The effects of P1 on osteoclasts appear to be mediated through the inhibition of NF-kappaB and JNK activation induced by the osteoclastogenic cytokine, receptor activator of NF-kappaB ligand (RANKL). These results provide an evidence for the potential usefulness of P1 for the treatment of bone-resorbing diseases.