[An investigation of trichloroethylene-induced effects on histone methylation in L-02 hepatic cells]

Objective: To further explore TCE-induced hepatotoxicity and its mechanisms by identification of trichloroethylene (TCE) induced abnormal histone methylation in human liver cells. Methods: L-02 cells were treated with 0 and 8 mmol/L TCE for 24 h. Histones were extracted by acid. Liquid chromatography electrospray ionization tandem mass spectrometry (ESI-LC-MS/MS) were used to identify and quantify TCE related histone methylations. TCE induced abnormal methylation of H3K79 me2 and H3K79 me3 were validated by Western blot analysis. The further analysis of the function of histone abnormal methylation modifications were done by single cell gel electrophoresis (SCGE) and Western blot analysis of p53 and ɤH2AX. Results: After treatment with TCE for 24 h in L-02 cells, the 36 TCE related histone methylation sites in 28 peptide segments were identified by MS. After treatment with TCE in concentrations of 0 and 8.0 mmol/L in L-02 cells for 24 h, the relative expression level of histone H3K79 me3 were 1.00±0.06, 0.70±0.09 (t=15.01, P=0.015); the relative expression level of histone H3K79 me2 were 1.00±0.05, 0.74±0.07 (t=16.69, P=0.018); the Olive Tail Moment about DNA damage were 1.46±0.28, 3.12± 0.68 (t=15.22, P=0.018); the relative expression levels of p53 were 1.00±0.04, 1.24±0.04 (t=18.71, P= 0.012); and the relative expression levels of ɤH2AX were 1.00 ± 0.03, 1.56 ± 0.11 (t=8.32, P=0 045). Conclusion: TCE can induce changes in the relative expression level of H3K79 me2 and H3K79 me3 in L-02 cell, and induce DNA damage, suggesting that TCE may induce changes in the relative expression level of H3K79 me2 and H3K79 me3 by DNA damage.

[Synthesis and antimalarial activities of fluorenemethanols]

For the purpose of improving the oral antimalarial activities of the fluorenemethanols (reported by us in previous articles) which were less effective by oral than by subcutaneous administration, 24 alpha-(alkylaminomethyl)-2, 7-dichloro-9-substituted benzylidene-4-fluorenemethanols (III) were synthesized. The results of preliminary screenings demonstrated that five compounds (No. 1-4, 8) exhibited significant antimalarial activities against Plasmodium berghei NK65 strain in mice by oral administration, at dose of 6.25 mg.kg-1.d-1 x 3 with suppressive rate of 100%. Further evaluation of these 5 compounds showed that 4 of them (No. 1-4) were superior to chloroquine in parallel tests, their ED50 and ED90 were 1.0, 1.6; 0.6, 0.9; 0.7, 1.5 and 0.8, 1.6 mg.kg-1.d-1 x 3 respectively, while the ED50 and ED90 of chloroquine were 1.9 and 2.9 mg.kg-1. d-1 x 3 respectively; one compound (No 8) was equal to chloroquine, its ED50 and ED90 were 1.5 and 3.2 mg.kg-1.d-1 x 3 respectively. Further assessment of these 4 compounds are in progress.

[Crystal and molecular structure of the antimalarial agent alpha-(dibutylaminomethyl)-2, 7-dichloro-9-(p-chlorobenzylidene)-4- fluorenemethanol(benflumetol)]

The three-dimensional crystal and molecular structure of benflumetol(I), alpha-(dibutylaminomethyl)-2, 7-dichloro-9-(p-chlorobenzylidene)-4-fluorenemethanol, was determined by X-ray crystallography and compared with the crystal structures of the cinchona alkaloids. The aromatic rings of fluorene-phenyl system of benflumetol are twisted from each other by 52.8 degrees. The torsion angle of N-C-C-O of benflumetol is 47.6 degrees. The intramolecular aliphatic N-O distance in benflumetol is 2.709A, which is close to the N-O distance found in antimalarial cinchona alkaloids. Benflumetol contains an intramolecular hydrogen bond between the aliphatic nitrogen and oxygen atoms, no intermolecular hydrogen bond was found, which is different from the known amino alcohol antimalarials.