A series of new polyimides (PIs) containing di-tert-butyl side groups were synthesized via a polycondensation of 1-(4-aminophenoxy)-4-(4-amino-2-methylphenyl)-2,6-di-tert-butylbenzene (3) with various aromatic tetracarboxylic dianhydrides. The novel unsymmetric PIs exhibited a low dielectric constants (2.78-3.02), low moisture absorption (0.53-1.35%), excellent solubility, and high glass transition temperature (308-450 C). The PI derived from the new diamine and the very rigid naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA) was soluble in N-methyl-2-pyrrolidone, chloroform, m-cresol, and cyclohexanone. The unsymmetric di-tert-butyl pendent groups significantly enhance the rotational barrier of the polymer chains; thus these PIs had high T g s. The 1 H NMR spectrum of the diamine 3 revealed that the protons of 4-aminophenoxy moiety are not chemical shift equivalent. This is because the steric hindrance of the bulky di-tert-butyl groups prevents the benzene ring of 4-aminophenoxy moiety from rotating freely.

Hepatocellular carcinoma (HCC) is the leading cause of cancer mortality in Asia. The aim of this study was to examine whether reactive oxygen species production is involved in quercetin-induced apoptosis in human HCC cell lines. Quercetin inhibited the growth of hepatoma cells in dose and time dependent manners. Quercetin treatment of hepatoma cells resulted in changes of cell cycle progression. The G0/G1phase was decreased and S phase was increased in HA22T/VGH cells after treatment with quercetin. The levels of apoptotic sub-G0/G1, reactive oxygen species and annexin V were increased prior to cell death and concurrent with lipid peroxidation in two human hepatoma cells after treatment with quercetin. Quercetin also enhanced the apoptotic effect of the chemotherapeutic agent, paclitaxel, in HA22T/VGH cells. Quercetin has therapeutic potential as an anti-cancer drug. These results provide basis for further study into the potential use of quercetin in combination with paclitaxel for treatment of hepatoma.

New N-1-adamantylcitraconimide (compound 1) and N-l-diamantylcitraconimide (compound 2) were synthesized by reaction of citraconic anhydride with 1-aminoadamantane, and 1-aminodiamantane, respectively, followed by imidiza-tion with acetic anhydride and sodium acetate. Compound 1, N-1-adamantylmaleimide (compound 3) and N-1-diamantyl-maleimide (compound 4) exhibited strong growth-inhibitory activity against four cancer cell lines (Colo 205, Hep G2, SK-BR-3 and Molt-4). Moreover, compound 1 showed relatively specific cytoxicity against the test tumor cell lines. Compound 2 exhibited growth inhibitory activity against Colo 205, and SK-BR-3 cells, similar to 5-fluorouracil. It was noted that compound 2 showed relatively low cytotoxicity against Molt-4 cells, approximately 42 times lower than 5-fluorouracil. The N-substituents of imides with adamantyl substituents have a more potent antitumor activity than the imides with diaman-tyl substituents. The imides with methyl substituents (compounds 1 and 2) showed relatively higher selectivity against the tested cancer cell lines than the imides without methyl substituents (compounds 3 and 4). Compounds 3 and 4 show good in vitro activities against Staphylococcus aureus and Trichophyton mentagrophytes. Compound 1 had weak antimicrobial activity against T. mentagrophytes.

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