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Ellipticine, olivacine, and their five reduced natural variants were synthesized via a palladium-catalyzed tandem cyclization/cross-coupling reaction as the key step. In addition, a previously unknown conformer of janetine was obtained through conformational inversion of the D ring in janetine. Because there are few synthetic approaches for reduced natural variants, little is known about the biological activities of these compounds. Six synthetic natural alkaloids and five of their derivatives were evaluated for their antiproliferative activity against HCT-116 and HL-60 cells. The activities of variants with the D-reduced ring or without the C(11)-Me group were lower than those of ellipticine. The conformer of guatambuine showed higher activities than guatambuine. [ABSTRACT FROM AUTHOR]

CCN3 is a matricellular protein that belongs to the CCN family. CCN3 consists of 4 domains: insulin-like growth factor-binding protein-like domain (IGFBP), von Willebrand type C-like domain (VWC), thrombospondin type 1-like domain (TSP1), and the C-terminal domain (CT) having a cysteine knot motif. Periostin is a secretory protein that binds to extracellular matrix proteins such as fibronectin and collagen. In this study, we found that CCN3 interacted with periostin. Immunoprecipitation analysis revealed that the TSP1-CT interacted with the 4 repeats of the Fas 1 domain of periostin. Immunofluorescence analysis showed co-localization of CCN3 and periostin in the periodontal ligament of mice. In addition, targeted disruption of the periostin gene in mice decreased the matricellular localization of CCN3 in the periodontal ligament. Thus, these results indicate that periostin was required for the matricellular localization of CCN3 in the periodontal ligament, suggesting that periostin mediated an interaction between CCN3 and the extracellular matrix. [ABSTRACT FROM AUTHOR]

Calothrixin B, whose structure consists of a pentacyclic indolo[3,2- j]phenanthridine framework, was originally isolated as a secondary metabolite from Calothrix cyanobacteria and was found to exhibit potent antiproliferative activity. In this study, treatment with 100 μM of calothrixin B did not inhibit the proliferation of HL-60 promyelocytic leukemia cells, the result indicated that calothrixin B could possess weaker activity against leukemia cells. In a previous study of the structure-antiproliferative activity relationships of calothrixin B analogs, the tetracyclic 5 H-pyrido[4,3- b]carbazole-4,11(6 H)-dione structure, which does not include the benzene ring found in calothrixin B, was reported to be necessary for antiproliferative activity; however, the induction of substituents on the indole nitrogen atom of calothrixin B decreased the antiproliferative activity of the compound. To develop calothrixin B analogs with good antiproliferative activity against both HL-60 and HCT-116 cells, we synthesized various N-substituted calothrixin B analogs and assessed their activity. Compared with calothrixin B, N-OMe calothrixin B displayed almost the same or slightly stronger antiproliferative activity against HCT-116 cells, whereas the N-MOM analog demonstrated slightly weaker activity against these cells. These two analogs also inhibited proliferation of HL-60 cells, whereas calothrixin B did not exhibit antiproliferative activity toward these cells. Among calothrixin B analogs, N-OMe and N-MOM calothrixins B are cytotoxic against HCT-116 cells and not the lack of the effect on HL-60 cells. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is hydrophilic and swells significantly when in contact with water. Here, we investigate the change in thickness of multilayer graphene oxide membranes due to intercalation of water, via humidity-controlled observation in an environmental scanning electron microscope (ESEM). The thickness increases reproducibly with increasing relative humidity. Electron energy loss spectroscopy (EELS) reveals the existence of water ice under cryogenic conditions, even in high vacuum environment. Additionally, we demonstrate that freezing then thawing water trapped in the multilayer graphene oxide membrane leads to the opening up of micron-scale inter-lamellar voids due to the expansion of ice crystals. [ABSTRACT FROM AUTHOR]