Inhibition of 3,3′,4,4′,5-Pentachlorobiphenyl-Induced Chicken Embryotoxicity by 2,2′,4,4′,5,5′-Hexachlorobiphenyl

3,3′,4,4′,5-Pentachlorobiphenyl (pentaCB) caused a dose-dependent induction of chicken embryolethality, malformations, edema, and liver lesions at doses ranging from 0.5 to 12.0 μg/kg. In contrast, no embryotoxicity was observed after treatment with 10, 25, or 50 mg/kg 2,2′,4,4′,5,5′-hexaCB. In eggs cotreated with 2.0 μg/kg, 3,3′,4,4′,5-pentaCB plus 10, 25, or 50 mg/kg 2,2′,4,4′,5,5′-hexaCB, there was significant protection from 3,3′,4,4′,5-pentaCB-induced embryo malformations, edema, and liver lesions, whereas no inhibition of embryolethality was observed. These results further extend the response-specific nonadditive interactions of binary mixtures of polychlorinated biphenyls (PCBs) and should be considered in the development of approaches for hazard assessment of PCB mixtures and related compounds.     

3′,4′,7-trihydroxyflavone inAlbizzia julibrissin

From the stembark ofAlbizzia julibrissin. 3′, 4′, 7-trihydroxyflavone and α-spinasteryl-d-glucoside were isolated.     

Distribution and excretion of 2,3,6,2′,3′,6′- and 2,4,5,2′,4′,5′-hexachlorobiphenyl in senescent rats

The disposition of two symmetrical [¹⁴C]hexachlorobiphenyls (HCBs), 2,3,6,2′,3′,6′-HCB (236) and 2,4,5,2′,4′,5′-HCB (245), was studied in 24-month-old male Sprague-Dawley rats after iv treatment. Because body composition changes with age, complete dissections were performed on all rats to determine the size of the skin and adipose tissue depots. More than 50% of 236 was metabolized and excreted via the bile into the feces within 2 days. In contrast, 245 redistributed from the liver, muscle, and skin to adipose tissue where it accumulated without being metabolized. Only 2% of the total dose of 245 was excreted primarily in the feces within 21 days. The data obtained in this study were compared to results previously obtained from 2- to 3-month-old rats in this laboratory (Matthews and Tuey, 1980, Toxicol. Appl. Pharmacol.53, 377–388). Although the general pattern of HCB disposition did not change with age, i.e., metabolism and excretion of 236 versus persistence of 245, there were differences in the rates of elimination and in the tissue levels. There was enhanced metabolite retention in the muscle, skin, and adipose tissue of older animals which suggested an age-related decrease in tissue clearance. The large volume of adipose tissue in these older Sprague-Dawley rats could in part explain this observation. In general, there were few changes in decay rates from tissues or in biliary excretion. Age had a greater effect on the disposition of the persistent 245 than on the metabolizable 236. Thus, changes in body composition seemed to play a major role in age-related changes in the distribution and excretion of polychlorinated biphenyls.     

Metabolite of 2,2′,4′,5-tetrabromobiphenyl, 3-methylsulphonyl-2,2′,4′,5-tetrabromobiphenyl,a potent inducer of CYP2B1/2 in rat

1. 3-Methylsulphonyl- and 4-methylsulphonyl-2,2',4',5-tetrabromobiphenyls (3-MeSO₂- and 4-MeSO₂-TetraBrBs) were detected in the liver, lung, kidney, adipose tissue and faeces of the 2,2',4',5-tetrabromobiphenyl (TetraBrB)-dosed rat. 2. The administration of 0.05-2.0 µmol kg^?1 doses of 3-MeSO₂-TetraBrB produced corrresponding increases in the hepatic concentration of the methyl sulphone metabolite, corresponding increases in the content of total cytochrome P450, and corresponding increases in the activities of 7-benzyloxy-, 7-ethoxy- and 7-pentoxyresorufin O-dealkylases. The inducing effects of the 3-MeSO₂-TetraBrB (0.2 µmol kg^?1), both on the content of total P450 and on the activities of the three alkoxyresorufin O-dealkylases, were higher than that of the parent TetraBrB (342 µmol kg^?1). 3. The major phenobarbital (PB)-inducible forms of P450, CYP2B1, CYP2B2, CYP3A2 and CYP2C6, were substantially induced by 3-MeSO₂-TetraBrB, but CYP1A1 and CYP1A2 were not. On the other hand, the activities of drug-metabolizing enzymes and the four PB-inducible forms of P450 were unchanged by 4-MeSO₂-TetraBrB treatment. 4. The induction profiles of these enzymes and P450 forms in rat treated with 3-MeSO₂-TetraBrB were similar to those treated with PB. 5. The inducing ability of 3-MeSO₂-TetraBrB (0.5 µmol kg^?1) both on the activities of the three alkoxyresorufin O-dealkylases and on the contents of four PB-inducible forms of P450 was roughly equal to that of PB (431 µmol kg^?1 twice at a 24-h interval) or 3-MeSO₂-2,2',4',5-tetrachlorobiphenyl (1 µmol kg^?1). It is noteworthy that the effects of 3-MeSO₂-TetraBrB on the drug-metabolizing enzymes CYP2B1 and CYP2B2 were several thousand-fold higher than those of parent TetraBrB, while the effect of its isomeric 4-MeSO₂-TetraBrB were not. 6. The extent of hepatic accumulation of the 3-MeSO₂ metabolite after the administration of TetraBrB (342 µmol kg^?1) was almost the same as that after the administration of 3-MeSO₂-TetraBrB (0.1-0.2 µmol kg^?1). The relationship between the hepatic concentration of the 3-MeSO₂ metabolite and the extent of enzyme induction after the administration of TetraBrB or 3-MeSO₂-TetraBrB suggests that 3-MeSO₂-TetraBrB plays an important role in the induction of microsomal drug-metabolizing enzymes by TetraBrB.     

Lipoprotein-mediated transfer of 2,4,5,2′,4′,5′-hexachlorobiphenyl into cultured human cells

1. The very low density, low density and high density lipoproteins (VLDL, LDL, HDL), centrifugally separated from human plasma treated with 2,4,5,2′,4′,5′-hexachloro[¹⁴C]biphenyl (¹⁴C-HCB) contained approximately 50% of the ¹⁴C-HCB.

2. Normal skin fibroblasts were incubated at 4°C or 37°C for varying times with medium containing 10% serum, LDL or HDL labelled with ¹⁴C-HCB. Cellular incorporation of ¹⁴C-HCB from serum was temperature-dependent and occurred mainly during the first 30 minutes. Cellular accumulation of ¹⁴C-HCB from isolated lipoproteins was also rapid and was more efficient from HDL than from LDL or serum. Accumulation from HDL was concentration-dependent and temperature-dependent.

3. The efflux of ¹⁴C-HCB from cells into serum- or lipoprotein-containing medium occurred very rapidly and was most effective in the presence of 20% serum. The order of efficiency in removal of HCB from cells was 20% serum, 50 μg LDL protein/ml, and 120 μg HDL protein/ml. Little or no efflux from cells occurred into serum-free, lipoprotein-free medium.

4. HDL may be involved in the delivery of HCB to cells, a role in contrast to the generally accepted theory that HDL transports lipids from cells.     

Synthesis and studies on antidepressant activity of 2′,4′,6′-trihydroxychalcone derivatives

In this study, we synthesized a series of 2′,4′,6′-trihydroxychalcone derivatives and evaluated their antidepressant activities. The results of the nine compounds showed significantly reduced times during the forced swimming test at a dose of 10?mg/kg, indicative of antidepressant activity. Among the compounds, 2-bromo-2′,4′,6′-trihydroxychalcone (3h) was found to be the most potent, and it was observed that compound 3h at dose of 10, 20, and 40?mg/kg significantly reduced the duration of immobility times in the FST and TST in mice 30?min after treatment.     

2,2′,3′,4,4′,5,5′-Heptachlorobiphenyl (PCB 180) — on its toxicokinetics,biotransformation and porphyrinogenic action in female rats

The toxicokinetics and biotransformation of 2,2,3,4,4,5,5-heptachlorobiphenyl, as well as its influence on the activity of microsomal and cytosolic enzymes and on the porphyrin pathway in the liver were studied in female rats following oral treatment with 7 mg/kg every other day for 3 months. One day after cessation of treatment the concentration of the compound in liver, spleen, CNS and blood was 100–500 times and in the trachea it was only 5 times less than in the adipose tissue. The daily excretion with the feces and urine amounted to 35 and 1.5 g, respectively. In both excreta, heptachlorobiphenylol was identified as a metabolite. The biotransformation rate was estimated to be about 5%. Investigations of the liver revealed increases in the relative liver weight, total cytochrome P-450 content, O-deethylation of 7-ethoxycoumarin and in the activity of glutathione S-transferases. Disturbances of the hepatic porphyrin pathway were not detected. Only at the end of a post-dosing period of 12 months did the hepatic uroporphyrinogen decarboxylase show diminished activity. Only one of these animals with diminished enzyme activity showed drastically elevated porphyrins. In these animals, the fecal and urinary porphyrins did not differ from controls. At no time did heptachlorobiphenyl influence the urinary excretion of delta-aminolevulinic acid and porphobilinogen. The results indicate 1) that this congener shows expected toxicokinetics with the exception of being accumulated in the trachea and 2) that this congener induces disturbances of the hepatic porphyrin pathway several months after cessation of treatment.     

Disposition of 2′, 3′-dideoxyadenosine and 2′, 3′-dideoxyinosine in mice

Summary Mice were dosed with [³H]2,3-dideoxyadenosine ([³H]ddA) in three procedures: intravenously, intraperitoneally, and interperitoneally following a dose of 2 -deoxycoformycin (dCF). For mice dosed intravenously, the content of radioactivity in plasma and tissue samples were essentially constant after 30 min. Of the radioactivity in plasma and brain samples collected between 30 min and 24 hr, more than 94% was present as ³H₂O, indicating that most of the tritium from [³H]ddA had exchanged with water. No intact ddA was detected, and the deamination product, 2,3 -dideoxyinosine (ddI), was present only transiently. In the urine, the major radioactive material was [³H]ddI. Also detected were ³H₂O and small amounts of [³H]hypoxanthine and [³H]ddA. Following intraperitoneal doses to mice, levels of radioactivity in plasma, liver, and kidney increased to a maximum by 15–30 min after dosing but dropped to essentially constant levels thereafter, again indicating that the tritium had exchanged with water. At 5, 15, and 30 min after dosing, ddI was the major radioactive component in plasma. Only small amounts of ddA were present. When dCF was administered 24 hr prior to intraperitoneal [³H]ddA, levels of radioactivity in plasma, liver, and kidney reached a maximum at 30 to 60 min after dosing and decreased to essentially constant levels thereafter. The dCF transiently inhibited the deamination of ddA to ddI, since, in plasma, [³H]ddA was the main radioactive component at 5 and 15 min after dosing. Comparison of HPLC assays based on radioactivity detection and UV absorbance showed that they were equivalent for measuring ddA and ddI in samples derived from dosed mice. Therefore, exchange of tritium must have occurred at a metabolic step beyond ddI.For mice dosed intravenously and orally with unlabeled ddI, there was evidence of a saturated process. Nevertheless, for the high and low intravenous doses of ddI, the percent of dose excreted in the urine as unchanged drug was the same.     

Sertoli cells proliferate in adult rats with prenatal exposure to 3,3′,4,4′,5-pentachlorobiphenyl

Sertoli cells play a critical role in spermatogenesis, and in adults, they are terminally differentiated with loss of proliferative activity. This study revealed Sertoli cell proliferation in 17-week-old Sprague–Dawley rats whose dams had been intragastrically administered 250 ng of 3,3′,4,4′,5-pentachlorobiphenyl/kg on days 13–19 postconception. Immunohistochemical evidence of proliferating cell nuclear antigen (PCNA) expression and electron microscope observation of mitotic figures confirmed the proliferation. Because the serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone concentrations were similar to those of vehicle-treated rats, a direct endocrine cause for the observed effects was unlikely.     

Tissue distribution metabolism and excretion of 2,2′,4,4′, 5-pentachlorodiphenyl ether in the rat

The tissue distribution, metabolism and excretion of ¹⁴C-2,2,4,4,5-pentachlorodiphenyl ether (PCDE) were studied in the rat. Radioactivity was distributed in all tissues examined, with the highest concentrations being found in the fat followed by the skin, liver, kidney and muscle. Most of the radioactivity found in the tissues was due to unchanged PCDE. Decay of PCDE in the blood was fitted to a four-compartment pharmacokinetic model, and the last compartment had a half-life of 5.8 days. A total of 55% and 1.3% of an orally administered dose was excreted in feces and urine, respectively, in 7 days. More than 64% of the fecal radioactivity was due to unchanged PCDE, while hydroxylated PCDE accounted for 23%.     

In vitro metabolism of 2,2′,3,4′,5,5′,6-heptachlorobiphenyl (CB187) by liver microsomes from rats,hamsters and guinea pigs

The metabolism of 2,2′,3,4′,5,5′,6-heptachlorobiphenyl (heptaCB) (CB187) was studied using liver microsomes of rats, hamsters and guinea pigs, and the effect of cytochrome P450 (CYP) inducers, phenobarbital (PB) and 3-methylcholanthrene (MC), was also investigated. In untreated animals, guinea pig liver microsomes formed three metabolites which were deduced to be 4′-hydroxy-2,2′,3,5,5′,6-hexachlorobiphenyl (M-1), 4′-hydroxy-2,2′,3,3′,5,5′,6-heptaCB (M-2) and 4-OH-CB187 (M-3) from the comparison of GC/MS data with some synthetic authentic samples. The formation rate of M-1, M-2 and M-3 was 18.1, 36.6, 14.7?pmol?h^?1?mg protein^?1, respectively. Liver microsomes of untreated rats and hamsters did not form CB187 metabolites. In guinea pigs, PB-treatment increased M-1 and M-2 significantly to 1.9- and 3.4-fold of untreated animals but did not affect the formation of M-3. In rats, PB-treatment resulted in the appearance of M-2 and M-3 with formation rates of 87.1 and 13.7?pmol?h^?1?mg protein^?1, respectively, but M-1 was not observed. In hamsters, PB-treatment formed only M-2 at a rate of 29.4?pmol?h^?1?mg protein^?1. On the other hand, MC-treatment of guinea pigs decreased the formation of M-1 and M-2 to less than 50% of untreated animals. MC-microsomes of rats and hamsters produced no metabolites. Preincubation of antiserum (300?µl) against guinea pig CYP2B18 with liver microsomes of PB-treated guinea pigs produced 80% inhibition of M-1 and the complete inhibition of M-2 and M-3. These results suggest that PB-inducible CYP forms, especially guinea pig CYP2B18, rat CYP2B1 and hamster CYP2B, are important in CB187 metabolism and that CB187 metabolism in guinea pigs may proceed via the formation of 3,4- or 3′,4′-oxide and subsequent NIH-shift or dechlorination.     

Promotion of Altered Hepatic Foci by 2,3′,4,4′,5-Pentachlorobiphenyl in Sprague–Dawley Female Rats

The tumor promotion potential of 2,3′,4,4′,5-pentachlorobiphenyl (PCB-118) was studied in a two-stage initiation/promotion bioassay in female Sprague–Dawley rats. The animals were initiated by intraperitoneal administration ofN-nitrosodiethylamine after partial hepatectomy. After 5 weeks of recovery, the promotion period commenced by once-weekly subcutaneous administrations of PCB-118 at six dose levels (10, 40, 160, 640, 2500, and 10,000 μg/kg body weight/week) for 20 weeks. In addition, three of these dose levels (40, 640, and 10,000 μg/kg body weight/week) were administered for 52 weeks. Evaluation of hepatic foci positive for glutathione S-transferase P demonstrated that the mono-orthochlorine substituted congener PCB-118 significantly increased the number of foci/cm³of liver in the two highest dose groups after 20 weeks, but did not significantly increase the percentage of the liver occupied by foci. After 52 weeks of treatment, both the percentage and the number of foci/cm³were significantly increased in the highest dose group. A toxic equivalency factor based on foci development during 20 weeks of treatment would be less than 0.00002. Altered relative liver and thymus weights were observed after treatment with both substances as well as an induction of methyl cholanthrene- and phenobarbital-inducible isoenzymes of cytochrome P450 monooxygenase. These results show that PCB-118 has a potency to enhance foci growth in rat liver, although the potency is low compared to that of structurally related compounds.     

2,3′,4,4′,5-Pentachlorobiphenyl impairs insulin-induced NO production partly through excessive ROS production in endothelial cells

Polychlorinated biphenyls (PCBs) have been reported to be associated with increased risk to hypertension, atherosclerosis, cardiovascular disease, etc. 2,3′,4,4′,5-Pentachlorobiphenyl, known as PCB-118, is a member of coplanar PCBs which renders their structure similar to polychlorinated dibenzo-p-dioxins (PCDDs) and has dioxin-like activity. In our current study, we investigated the effect of PCB-118 exposure on nitric oxide (NO) production and the underlying mechanisms in vitro. Exposure of PCB-118 impaired insulin-induced NO production and endothelial nitric oxide synthase (eNOS) activity in human umbilical vein endothelial cells (HUVECs) with no significant effect on cell viability. Furthermore, PCB-118 treatment induced oxidative stress. In addition, scavenging of reactive oxygen species (ROS) by 10?μM N-acetyl-l-cysteine (NAC) partly rescued impaired insulin-induced eNOS activities and NO productions induced by PCB-118 in HUVECs. Taken together, these results indicate that PCB-118 mediates lower eNOS activity and impairs insulin-induced NO production partly through excessive ROS production in endothelial cells.     

黄芩药材中2′,5,6′,7-四羟基二氢黄酮醇的分离与鉴定

目的:分离并鉴定黄芩药材中2′,5,6′,7-四羟基二氢黄酮醇。方法:依托以Lipid A为靶点的抗内毒素(LPS)药物筛选平台,应用大孔吸附树脂、膜和高效液相色谱法对黄芩水提液进行针对Lipid A的逐级分离纯化,对所得目标化合物采用质谱、核磁共振和红外光谱等技术进行结构解析。结果:从黄芩水提液中分离出活性化合物5KL-1B,其与LipidA的特异性结合值为208.6arc seconds,结构鉴定确证5KL-1B为2′,5,6′,7-四羟基二氢黄酮醇。结论:本试验建立的定向分离模式目的性强、效率高,可用于天然药物中抗LPS活性物质的富集与分离纯化。     

Metabolites of 2,4′,5-trichlorobiphenyl in rats

1. Nineteen metabolites of 2,4′,5-trichlorobiphenyl were isolated from rat urine, faeces and bile. These metabolites resulted from one or more of the following transformations: dechlorination, hydroxylation, thiolation, methylthiolation, methylthio oxidation, dihydrodiol formation, mercapturic acid formation and conjugation with glucuronic acid.

2. Mercapturic acid-pathway metabolites were the major metabolites in the bile.

3. Methylthio-, methylsulphinyl- and methylsulphonyl-containing metabolites were the major metabolites in the faeces of control rats.

4. A synthetic pathway for the preparation of sulphur-containing metabolites of trichlorobiphenyl is described.     

Apoptotic effect of synthetic 2′,4′,5′-trimethoxychalcones in human K562 and Jurkat leukemia cells

In this study, we assessed the cytotoxic effect of synthetic 2′,4′,5′-trimethoxychalcones on the human K562 acute myeloid leukemia cell and human Jurkat acute lymphoid leukemia cell. Compounds 13, 16, 19, and 26 showed low IC₅₀ values (4.10–8.56 μM at 72 h) for both cell lines and did not have a cytotoxic effect on normal human lymphocytes. The mechanism of cell death induced by these compounds involves a decrease in the expression of cell proliferation marker Ki67, suggesting inhibition of cell proliferation. Furthermore, these chalcones reduced mitochondrial potential, decreased Bcl-2 expression, and increased Bax expression, indicating that the mechanism of apoptosis induced by them involves the intrinsic apoptosis pathway. The mechanism of action also involves increase in active caspase-3 and decrease in survivin expression. These results support the chalcones as potential antitumoral agents for further optimization.     

Synthesis and biological evaluation of novel 2′,4′,5′-trimethoxyflavonol derivatives as anti-inflammatory and antimicrobial agents

A series of novel 3-hydroxy-2-(2,4,5-trimethoxyphenyl)-4H-chromen-4-one (flavonol) derivatives (2a–u) of biological interest have been prepared via CLAISEN–SCHMIDT condensation followed by ALGAR–FLYNN–OYAMADA reaction and to search for the potent nonsteroidal anti-inflammatory agents from this novel series. All the synthesized compounds have been screened for their in vitro proinflammatory cytokines tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) inhibitory activity along with antimicrobial activity. As many as three compounds viz. 2h, 2l, and 2q from this novel series were found to be potent TNF-α and IL-6 inhibitor (up to 72–81 % TNF-α and 86–92 % IL-6 inhibitory activity) but at 10 μM concentration as compared with the standard dexamethasone (71 % TNF-α and 84 % IL-6 inhibitory activities at 1 μM concentration). While the compounds 2d, 2m, 2n, and 2s were found to be potent antimicrobial agent showing even 2–2.5-fold more potency than that of standard ciprofloxacin and miconazole at the same MIC value of 10 μg/mL.     

3′,5′-环化腺苷酸的生产

近几年来,3’,5’—环化腺苷酸(cAMP)作为第二信使物质来研究它的作用机理颇为活跃。许多研究结果表明,cAMP的作用已远远超过了激素传导物质的含意,它不但对代谢、核酸、蛋白质的合成调节,而且对分泌、运动、神经刺激的传导以及组织的形成、分化、癌变等领域皆有密切关系。使得凡从事生命科学及医学科学的人们不得不重视对它的研究。为此对摸索一条合适的生产cAMP的工艺来满足理论研究需要及试制针药提供临床试验已日显重要。