RESUMO
To study the toxicity of 3-hydroxybenzo[c]phenanthrene (3-OHBcP), a metabolite of benzo[c]phenanthrene (BcP), first we compared it with its parent compound, BcP, using an in ovo-nanoinjection method in Japanese medaka. Second, we examined the influence of 3-OHBcP on bone metabolism using goldfish. Third, the detailed mechanism of 3-OHBcP on bone metabolism was investigated using zebrafish and goldfish. The LC50s of BcP and 3-OHBcP in Japanese medaka were 5.7 nM and 0.003 nM, respectively, indicating that the metabolite was more than 1900 times as toxic as the parent compound. In addition, nanoinjected 3-OHBcP (0.001 nM) induced skeletal abnormalities. Therefore, fish scales with both osteoblasts and osteoclasts on the calcified bone matrix were examined to investigate the mechanisms of 3-OHBcP toxicity on bone metabolism. We found that scale regeneration in the BcP-injected goldfish was significantly inhibited as compared with that in control goldfish. Furthermore, 3-OHBcP was detected in the bile of BcP-injected goldfish, indicating that 3-OHBcP metabolized from BcP inhibited scale regeneration. Subsequently, the toxicity of BcP and 3-OHBcP to osteoblasts was examined using an in vitro assay with regenerating scales. The osteoblastic activity in the 3-OHBcP (10-10 to 10-7 M)-treated scales was significantly suppressed, while BcP (10-11 to 10-7 M)-treated scales did not affect osteoblastic activity. Osteoclastic activity was unchanged by either BcP or 3-OHBcP treatment at each concentration (10-11 to 10-7 M). The detailed toxicity of 3-OHBcP (10-9 M) in osteoblasts was then examined using gene expression analysis on a global scale with fish scales. Eight genes, including APAF1, CHEK2, and FOS, which are associated with apoptosis, were identified from the upregulated genes. This indicated that 3-OHBcP treatment induced apoptosis in fish scales. In situ detection of cell death by TUNEL methods was supported by gene expression analysis. This study is the first to demonstrate that 3-OHBcP, a metabolite of BcP, has greater toxicity than the parent compound, BcP.
RESUMO
The first thiohalide µ3-capped octahedral hexanuclear technetium clusters with 24 valence electrons, [Tc6(µ3-S)8-n(µ3-Br)nBr6]n-4 [n = 1 ([Tc-S7Br]3-) and n = 2 ([Tc-S6Br2]2-)] and [Tc6(µ3-S)7(µ3-Cl)Cl6]3- ([Tc-S7Cl]3-), were synthesized and characterized. The structures of [Tc-S7Br]3-, [Tc-S6Br2]2-, and [Tc-S7Cl]3- were determined by single-crystal X-ray analysis. The Tc-Tc bond distances in [Tc-S7Br]3-, [Tc-S6Br2]2-, and [Tc-S7Cl]3- are 2.5842(6)-2.6029(6) Å (avg. 2.593(2) Å), 2.5835(10)-2.6049(10) Å (avg. 2.596(1) Å), and 2.5829(4)-2.5940(4) Å (avg. 2.587(3) Å), respectively. The capping halide and sulfide ligands in [Tc-S7Br]3-, [Tc-S6Br2]2-, and [Tc-S7Cl]3- were disordered in the crystals. The bond distances of Tc-S/Br as a function of the occupancies of the capping bromides for [Tc-S6Br2]2-, [Tc-S7Br]3-, and [Tc6(µ3-S)8Br6]4- ([Tc-S8]4-) showed a linear correlation. The one-electron reduction waves assignable to the Tc/TcIITc [Tc6(24e/25e)] process were observed for the novel complexes. Density functional theory (DFT) calculations of the hexanuclear technetium complexes showed a smaller energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the hexanuclear technetium complexes compared to those of the rhenium analogues. The electronic transitions of the new technetium complexes shifted to lower energy compared to the isotypic rhenium complexes.
