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Tyrosyl‐DNA phosphodiesterase 2 (TDP2) is a recently discovered DNA repair enzyme that can repair topoisomerase 2‐mediated DNA damage, resulting in cancer cell resistance. In this study, two compounds, robustadial A and B, were isolated from a fraction of the ethyl acetate extract of Eucalyptus globulus Labill. fruits based on TDP2 inhibition screening. The biological experiments indicated that robustadial A and B have TDP2 inhibitory activity with EC50 values of 17 and 42 μM, respectively, but no tyrosyl‐DNA phosphodiesterase 1 inhibition at 100 μM. Robustadial A showed significant synergistic effects with the anticancer drug etoposide in four human cancer cell lines, non‐small cell lung cancer cell line (A549), prostate cancer cell line (DU145), breast cancer cell line (MCF‐7), colorectal adenocarcinoma cell line (HCT‐116), and chicken lymphoma cell line (DT40), and chicken lymphoma cell line complementation with human TDP2 (DT40 hTDP2) with combination index values ranging from 0.21 to 0.74. This work will facilitate future efforts for the development of robustadial A‐based TDP2 selective inhibitors. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of main-chain liquid-crystalline polymers (LCPs) with pendant sulfonic acid groups have been synthesized by use of biphenyl-4,4′-diol, 6,7-dihydroxynaphthalene-2-sulfonic acid, and bis(4-(chlorocarbonyl)phenyl) decanedioate in a one-step esterification reaction. Emeraldine base form of polyaniline (PAN) is doped by the synthesized sulfonic acid-containing LCPs to obtain PAN-LCP ionomers. A series of electrorheological (ER) fluids are prepared using the synthesized PAN-LCP ionomers and silicone oil. The chemical structure, liquid-crystalline behavior, dielectric property of LCPs, and PAN-LCP ionomers, and ER effect of the ER fluids are characterized by use of various experimental techniques. The synthesized sulfonic acid-containing LCPs and PAN-LCP ionomers display nematic mesophase. The PAN-LCP ionomers show a slight elevation of glass transition temperatures and decrease of enthalpy changes of nematic-isotropic phase transition compared with corresponding sulfonic acid-containing LCPs. The relative permittivity of the PAN-LCP ionomers is much higher than that of the corresponding sulfonic acid-containing LCPs. The ER effect of the PAN-LCP ionomer dispersions is better than PAN dispersions, suggesting a synergistic reaction should be occurred among liquid crystalline component, and PAN part under electric fields. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3395-3403, 2013 [ABSTRACT FROM AUTHOR]

The article discusses a study which synthesized chiral side-chain liquid-crystalline polymers from smectic-nematic monomer and nonmesogenic chiral monomer. It notes that graft copolymerization was performed in this study, with polymethylhydrosiloxane serving as backbone. Results of the study showed that both smectic and nematic phases of the monomer occurred during the heating and cooling cycle. The study also observed nonmesogenic chiral moiety, as well as lower glass transition temperature.

The article presents a study which examined the effect on phase behaviors of side-chain chiral liquid crystalline elastomers of the different rigidity of the chiral crosslinker. It investigated the chemical structure of the monomers and polymers. It found that the isotropization temperature values of PII series are higher than those of PI series.