KS900: A hypoxia-directed, reductively activated methylating antitumor prodrug that selectively ablates O-alkylguanine-DNA alkyltransferase in neoplastic cells

To most effectively treat cancer it may be necessary to preferentially destroy tumor tissue while sparing normal tissues. One strategy to accomplish this is to selectively cripple the involved tumor resistance mechanisms, thereby allowing the affected anticancer drugs to gain therapeutic efficacy. Such an approach is exemplified by our design and synthesis of the intracellular hypoxic cell activated methylating agent, 1,2-bis(methylsulfonyl)-1-methyl-2-[[1-(4-nitrophenyl)ethoxy]carbonyl]hydrazine (KS900) that targets the O-6 position of guanine in DNA. KS900 is markedly more cytotoxic in clonogenic experiments under conditions of oxygen deficiency than the non-intracellularly activated agents KS90, and 90M, when tested in O⁶-alkylguanine-DNA alkyltransferase (AGT) non-expressing cells (EMT6 mouse mammary carcinoma, CHO/AA8 hamster ovary, and U251 human glioma), and than temozolomide when tested in AGT expressing cells (DU145 human prostate carcinoma). Furthermore, KS900 more efficiently ablates AGT in HL-60 human leukemia and DU145 cells than the spontaneous globally activated methylating agent KS90, with an IC₅₀ value over 9-fold lower than KS90. Finally, KS900 under oxygen-deficient conditions selectively sensitizes DU145 cells to the chloroethylating agent, onrigin, through the ablation of the resistance protein AGT. Thus, under hypoxia, KS900 is more cytotoxic at substantially lower concentrations than methylating agents such as temozolomide that are not preferentially activated in neoplastic cells by intracellular reductase catalysts. The necessity for intracellular activation of KS900 permits substantially greater cytotoxic activity against cells containing the resistance protein O⁶-alkylguanine-DNA alkyltransferase (AGT) than agents such as temozolomide. Furthermore, the hypoxia-directed intracellular activation of KS900 allows it to preferentially ablate AGT pools under the oxygen-deficient conditions that are present in malignant tissue.     

1,2-Bis(methylsulfonyl)-1-(2-chloroethyl)-2-[[1-(4-nitrophenyl)ethoxy]carbonyl]hydrazine (KS119): a cytotoxic prodrug with two stable conformations differing in biological and physical properties

The anticancer prodrug 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-[[1-(4-nitrophenyl)ethoxy]carbonyl]hydrazine (KS119) selectively releases a short-lived cytotoxin following enzymatic reduction in hypoxic environments found in solid tumors. KS119, in addition to two enantiomers, has two stable atropisomers (conformers differing in structure owing to hindered bond rotation) that interconvert at 37 °C in aqueous solution by first-order kinetics with t(1/2) values of ～50 and ～64 h. The atropisomers differ in physical properties such as partition coefficients that allow their chromatographic separation on non-chiral columns. A striking difference in the rate of metabolism of the two atropisomers occurs in intact EMT6 murine mammary carcinoma cells under oxygen-deficient conditions. A structurally related molecule, 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-[[1-(3-hydroxy-4-nitrophenyl)ethoxy]carbonyl]hydrazine (KS119WOH), was also found to exist in similar stable atropisomers. The ratio of the atropisomers of KS119 and structurally related agents has the potential to impact the bioavailability, activation, and therapeutic activity. Thus, thermally stable atropisomers/conformers in small molecules can result in chemically and enantiomerically pure compounds having differences in biological activities.     

Quantitative relationship between guanine O-alkyl lesions produced by Onrigin™ and tumor resistance by O-alkylguanine-DNA alkyltransferase

O⁶-Alkylguanine-DNA alkyltransferase (AGT) mediates tumor resistance to alkylating agents that generate guanine O⁶-chloroethyl (Onrigin™ and carmustine) and O⁶-methyl (temozolomide) lesions; however, the relative efficiency of AGT protection against these lesions and the degree of resistance to these agents that a given number of AGT molecules produces are unclear. Measured from differential cytotoxicity in AGT-ablated and AGT-intact HL-60 cells containing 17,000 AGT molecules/cell, AGT produced 12- and 24-fold resistance to chloroethylating (90CE) and methylating (KS90) analogs of Onrigin™, respectively. For 50% growth inhibition, KS90 and 90CE generated 5,600 O⁶-methylguanines/cell and ∼300 O⁶-chloroethylguanines/cell, respectively. AGT repaired O⁶-methylguanines until the AGT pool was exhausted, while its repair of O⁶-chloroethylguanines was incomplete due to progression of the lesions to AGT-irreparable interstrand DNA cross-links. Thus, the smaller number of O⁶-chloroethylguanine lesions needed for cytotoxicity accounted for the marked degree of resistance (12-fold) to 90CE produced by AGT. Transfection of human or murine AGT into AGT deficient transplantable tumor cells (i.e., EMT6, M109 and U251) generated transfectants expressing AGT ranging from 4,000 to 700,000 molecules/cell. In vitro growth inhibition assays using these transfectants treated with 90CE revealed that AGT caused a concentration dependent resistance up to a level of ∼10,000 AGT molecules/cell. This finding was corroborated by in vivo studies where expression of 4,000 and 10,000 murine AGT molecules/cell rendered EMT6 tumors partially and completely resistant to Onrigin™, respectively. These studies imply that the antitumor activity of Onrigin™ stems from guanine O⁶-chloroethylation and define the threshold concentration of AGT that negates its antineoplastic activity.     

O6-苄基鸟嘌呤增强1，3-二（2-氯乙基）-亚硝基脲对人肝癌细胞及其移植瘤的抗肿瘤作用

应用噻唑蓝（MTT）法检测O⁶-苄基鸟嘌呤(O⁶-BG)与1,3-二（2-氯乙基）-亚硝基脲（BCNU）合用的细胞毒作用及透射电镜检测凋亡细胞的方法研究了O⁶-BG对O⁶-烷基鸟嘌呤-DNA烷基转移酶（O⁶-AGT）阳性的人肝癌细胞SMMC-7721对BCNU细胞毒作用敏感性的影响及其与BCNU合用治疗移植瘤的协同效果. 结果显示：1.5-6.0 mg·L^-1的O⁶-BG预先作用2 h后,SMMC- 7721细胞对BCNU的敏感性明显增加;0.75-6.0 mg·L^-1的O⁶-BG可完全快速地抑制肿瘤细胞的AGT活性并持续12 h; ip 90 mg·kg^-1的O⁶-BG预处理2 h后给予25 mg·kg^-1的BCNU治疗,可使动物sc接种的人肝癌移植瘤生长延迟38.6 d, 诱导肿瘤细胞凋亡,并且可明显抑制肿瘤组织的转移酶活性. 说明O⁶-BG与BCNU合用于AGT阳性的肿瘤将具有明显的治疗效果.     

In vitro pharmacokinetics and pharmacodynamics of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)

The relationship between treatment efficacy and the pharmacokinetics (PK) and pharmacodynamics (PD) of anticancer drugs is poorly defined. 1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) is an alkylating agent used in the treatment of brain and other forms of cancer. It is postulated that BCNU kills cells by forming DNA interstrand cross-links. The present study was undertaken to characterize the PK and PD of BCNU in mouse L1210 cells. L1210 cells were exposed to BCNU (0-160 microM) and analyzed for intracellular BCNU concentrations, DNA interstrand cross-links, cell cycle phase, and cytotoxicity. The half-life of BCNU in cells was approximately 40 min. The maximum reduction of mitochondrial enzyme activity (maximum cell death) achieved within 24 hr after exposure to BCNU was concentration-dependent and could be described by a Hill equation. At lower concentrations, the area under the DNA interstrand cross-link-time curve linearly correlated with the maximum cell death and the area under the BCNU concentration-time curve. BCNU induced cell accumulation in the G(2)/M phase of the cell cycle, which continued even after apparent completion of cross-link repair. Loss of membrane permeability was minimal (approximately 2%) during the first 24 hr. Thereafter, cells died exponentially over the next 9 days, primarily by necrosis. In conclusion, while cytotoxicity was concentration-dependent, an indirect relationship was found among the time-course of BCNU concentrations, DNA interstrand cross-links, and cell death. Because of the disparity between the time-scale of PK and PD, focusing only on the early events may provide limited information about the process of anticancer drug-induced cell death.     

The polymorphic human glutathione transferase T1-1, the most efficient glutathione transferase in the denitrosation and inactivation of the anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea

A member of the Theta class of human glutathione transferases (GST T1-1) was found to display the greatest catalytic activity towards the cytostatic drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) of the GSTs studied. In this investigation (the most extensive to date), enzymes from four classes of the soluble human GSTs were heterologously expressed, purified, and kinetically characterized. From the 12 enzymes examined, only GST M2-2, GST M3-3 and GST T1-1 had significant activities with BCNU. This establishes that the activity is not a characteristic of a particular class of GSTs. Although GST M3-3 was previously reported to have the greatest activity with BCNU, the current investigation demonstrates that GST M2-2 is equally active and that GST T1-1 has an approximately 20-fold higher specific activity than either of the Mu class enzymes. A more rigorous kinetic analysis of GST T1-1 gave the following parameters with BCNU: a k(cat) of 0.035 +/-0.003s(-1) and a K(M) of 1.0 +/- 0.1mM. The finding that GST T1-1 has the highest activity towards BCNU is significant since GST T1-1 is expressed in the brain, a common target for BCNU treatment. Furthermore, the existence of a GST T1-1 null allele in up to 60% in some populations, may influence both the sensitivity of tumors to chemotherapy and the severity of adverse side-effects in patients treated with this agent.     

Search for Compounds with Hypoglycemic Activity in the Series of 1-[2-(1H-Tetrazol-5-yl)-R1-phenyl]-3-R2-phenyl(ethyl)ureas and R1-Tetrazolo[1,5-c]quinazolin-5(6H)-ones

Methods of 1-[2-(1H-tetrazol-5-yl)-R¹-phenyl]-3-R²-phenyl(ethyl)ureas and R¹-tetrazolo[1,5-c]quinazolin-5(6H)-ones synthesis were designed. IR, LC-MS, ¹H NMR, and elemental analysis data evaluated the structure and purity of the obtained compounds. Different products, depending on the reaction conditions, were distinguished and discussed. The preliminary hypoglycemic activity of 36 synthesized compounds was revealed. Docking studies to 11β-hydroxysteroid dehydrogenase 1, γ-peroxisome proliferator-activated receptor, and dipeptidyl peptidase-4 were conducted. Eight of these substances were further tested on glucocorticoid-induced insulin resistance models, namely glucose tolerance, oral rapid insulin, and adrenalin tests. One of the most active compounds turned out to be tetrazolo[1,5-c]quinazolin-5(6H)-one 3.1, exceeding the reference drugs Metformin (50 and 200 mg/kg) and Gliclazide (50 mg/kg).     

Anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)- 2-butenal are mediated by inhibition of the STAT3 pathway

Background and Purpose

Products of Maillard reactions between aminoacids and reducing sugars are known to have anti-inflammatory properties. Here we have assessed the anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal and its possible mechanisms of action.

Experimental Approach

We used cultures of LPS-activated macrophages (RAW264.7 cells) and human synoviocytes from patients with rheumatoid arthritis for in vitro assays and the collagen-induced arthritis model in mice. NO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities were measured in vitro and in joint tissues of arthritic mice, along with clinical scores and histopathological assessments. Binding of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal to STAT3 was evaluated by a pull-down assay and its binding site was predicted using molecular docking studies with Autodock VINA.

Key Results

(E)-2,4-bis(p-hydroxyphenyl)-2-butenal (2.5–10 μg·mL⁻¹) inhibited LPS-inducedNO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities in macrophage and human synoviocytes. This compound also suppressedcollagen-induced arthritic responses in mice by inhibiting expression of iNOS and COX2, and NF-κB/IKK and STAT3 activities; it also reduced bone destruction and fibrosis in joint tissues. A pull-down assay showed that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal interfered with binding of ATP to STAT3. Docking studies suggested that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal bound to the DNA-binding interface of STAT3 possibly inhibiting ATP binding to STAT3 in an allosteric manner.

Conclusions and Implications

(E)-2,4-bis(p-hydroxyphenyl)-2-butenal exerted anti-inflammatory and anti-arthritic effects through inhibition of the NF-κB/STAT3 pathway by direct binding to STAT3. This compound could be a useful agent for the treatment of arthritic disease.     

Differential inactivation of polymorphic variants of human O6-alkylguanine-DNA alkyltransferase

The human DNA repair protein O(6)-alkylguanine-DNA alkyltransferase (hAGT) is an important source of resistance to some therapeutic alkylating agents and attempts to circumvent this resistance by the use of hAGT inhibitors have reached clinical trials. Several human polymorphisms in the MGMT gene that encodes hAGT have been described including L84F and the linked double alteration I143V/K178R. We have investigated the inactivation of these variants and the much rarer variant W65C by O(6)-benzylguanine, which is currently in clinical trials, and a number of other second generation hAGT inhibitors that contain folate derivatives (O(4)-benzylfolic acid, the 3' and 5' folate esters of O(6)-benzyl-2'-deoxyguanosine and the folic acid gamma ester of O(6)-(p-hydroxymethyl)benzylguanine). The I143V/K178R variant was resistant to all of these compounds. The resistance was due solely to the I143V change. These results suggest that the frequency of the I143V/K178R variant among patients in the clinical trials with hAGT inhibitors and the correlation with response should be considered.     

Enhancements of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism and carcinogenic risk via NNK/arsenic interaction

Epidemiological studies indicated an enhancement of cigarette smoke-induced carcinogenicity, including hepatocellular carcinoma, by arsenic. We believe that arsenic will enhance the expression of hepatic CYP2A enzyme and NNK metabolism (a cigarette smoke component), thus its metabolites, and carcinogenic DNA adducts. Male ICR mice were exposed to NNK (0.5 mg/mouse) and sodium arsenite (0, 10, or 20 mg/kg) daily via gavaging for 10 days and their urine was collected at day 10 for NNK metabolite analysis. Liver samples were also obtained for CYP2A enzyme and DNA adducts evaluations. Both the cyp2a4/5 mRNA levels and the CYP2A enzyme activity were significantly elevated in arsenic-treated mice liver. Furthermore, urinary NNK metabolites in NNK/arsenic co-treated mice also increased compared to those treated with NNK alone. Concomitantly, DNA adducts (N(7)-methylguanine and O(6)-methylguanine) were significantly elevated in the livers of mice co-treated with NNK and arsenic. Our findings provide clear evidence that arsenic increased NNK metabolism by up-regulation of CYP2A expression and activity leading to an increased NNK metabolism and DNA adducts (N(7)-methylguanine and O(6)-methylguanine). These findings suggest that in the presence of arsenic, NNK could induce greater DNA adducts formation in hepatic tissues resulting in higher carcinogenic potential.     

Growth Inhibitory Effect of (E)-2,4-bis(p-hydroxyphenyl)-2-Butenal Diacetate through Induction of Apoptotic Cell Death by Increasing DR3 Expression in Human Lung Cancer Cells

The Maillard Reaction Products (MRPs) are chemical compounds which have been known to be effective in chemoprevention. Death receptors (DR) play a central role in directing apoptosis in several cancer cells. In our previous study, we demonstrated that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal, a MRP product, inhibited human colon cancer cell growth by inducing apoptosis via nuclear factor-κB (NF-κB) inactivation and G₂/M phase cell cycle arrest. In this study, (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate, a new (E)-2,4-bis(p-hydroxyphenyl)-2-butenal derivative, was synthesized to improve their solubility and stability in water and then evaluated against NCI-H460 and A549 human lung cancer cells. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate reduced the viability in both cell lines in a time and dose-dependent manner. We also found that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate increased apoptotic cell death through the upregulation of the expression of death receptor (DR)-3 and DR6 in both lung cancer cell lines. In addition to this, the transfection of DR3 siRNA diminished the growth inhibitory and apoptosis inducing effect of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate on lung cancer cells, however these effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate was not changed by DR6 siRNA. These results indicated that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate inhibits human lung cancer cell growth via increasing apoptotic cell death by upregulation of the expression of DR3.     

Interaction of mammalian O(6)-alkylguanine-DNA alkyltransferases with O(6)-benzylguanine

Human O(6)-alkylguanine-DNA alkyltransferase (hAGT) activity is a major factor in providing resistance to cancer chemotherapeutic alkylating agents. Inactivation of hAGT by O(6)-benzylguanine (BG) is a promising strategy for overcoming this resistance. Previous studies, which have focused on the region encompassed by residues Pro138 to Gly173, have identified more than 100 individual mutations located at 23 discrete sites at which alterations can render AGT less sensitive to BG. We have now extended the examination of possible sites in hAGT at which alterations might lead to BG resistance to include the residues from Val130 to Asn137, which also make up part of the binding pocket into which BG is postulated to fit. A further 21 mutations located at positions Gly132, Met134, Arg135, and Gly136 were found to lower sensitivity to BG. Mutants R135L, R135Y, and G136P were the most strikingly resistant, with a 50-fold increase in the amount of BG needed to obtain 50% inactivation. These results therefore increase the number of sites at which BG resistance can occur in response to a single amino acid change to 27. Although mammalian AGTs are very similar in amino acid sequence, mouse AGT (mAGT) is significantly less sensitive to BG than rat AGT (rAGT) or hAGT. Construction of chimeric proteins in which portions came from the rAGT and the mAGT indicated that the difference in inactivation resided solely in the amino acids located in the sequence from residues 150 to 188. Individual mutations of the three residues where rAGT and mAGT differ in this region showed that the principal reason for the reduced ability of the mAGT to react with BG was the presence of a histidine residue at position 161, which is occupied by asparagine in rAGT and hAGT. These experiments indicate that many minor changes in amino acids forming all parts of the nucleoside binding pocket of AGT can alter its ability to react with BG and that the possibility that polymorphisms or variants may occur reducing the effectiveness of combination therapy with BG and alkylating agents must be considered.     

Enhanced DNA excision repair in CCRF-CEM cells resistant to 1,3-bis(2-chloroethyl)-1-nitrosourea,quantitated using the single cell gel electrophoresis (Comet) assay

Enhanced DNA repair activity is important for the development of cellular resistance to alkylating agents. Here, we quantitated the kinetics of DNA excision repairs initiated by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in human leukemia CCRF-CEM cells. CEM cells that had been established resistant to BCNU (CEM-R) were evaluated in comparison with parental CEM cells (CEM-S). The excision repair kinetics were quantitated as the amount of DNA single strand breaks, which were generated from the incision/excision of the damaged DNA and were diminished by the rejoining of renewed DNA, using the single cell gel electrophoresis (Comet) assay. CEM-R cells were 10-fold more resistant to BCNU than CEM-S cells, and also showed cross-resistance to melphalan and cisplatin. In response to the treatment with BCNU, both CEM-S and CEM-R cells initiated an incision/excision reaction at the end of the incubation period, and completed the rejoining process within 4 hr. While CEM-S cells could not repair the damage induced by the high concentration of BCNU, CEM-R cells completed the repair process regardless of BCNU concentrations, suggesting enhanced excision repairs in CEM-R cells. The excision repair activity of CEM-R cells was increased with regard to the incision reaction and to the rate of the repair. Similar results were obtained using ultraviolet C, suggesting enhanced nucleotide excision repair in CEM-R cells. Thus, the enhanced DNA excision repairs were successfully quantitated in the resistant leukemic cell line using the Comet assay. The evaluation of the repair activity may predict the sensitivity of cancer cells to chemotherapy and provide a clue to overcome the resistance.     

On the formation of 4-[N,N-bis(2-chloroethyl)amino]phenyl acetic acid esters of hecogenin and aza-homo-hecogenin and their antileukemic activity

The p-[N,N-bis(2-chloroethyl)amino]phenylacetic acid esters of hecogenin and aza-homo-hecogenin have been prepared and their antineoplastic activity was evaluated against two basic drug screening systems in rodents, P388 lymphocytic and L1210 lymphoid murine leukemias. Among the compounds tested, the p-[N,N-bis(2-chloroethyl)amino]phenylacetic acid ester of aza-homo-hecogenin was appeared to possess a significant higher antileukemic effect. These results support that the alkylating esters of hecogenin produce important antitumor activity as well as, indicate that the aza-homo-hecogenin ester exhibits significantly higher activity due to lactam group (-NHCO-) modification.     

S-3(-三氟甲基)-6，7-双[4(-三氟甲基)苯基]-3，4-二氢喹啉-2(1H)-酮下调STAT3信号通路抑制人结直肠癌细胞生长的作用研究

目的 基于信号转导和转录活化因子3（STAT3）信号通路探讨三氟甲基化二氢喹喔啉酮类化合物S-3-（三氟甲基）-6,7-双［4-（三氟甲基）苯基］-3,4-二氢喹啉-2（1H）-酮（2o）对人结直肠癌细胞生长的抑制作用。方法 采用 MTT法检测三氟甲基化二氢喹喔啉酮类化合物 2b、2e、2f、2g、2k、2l、2m、2o、2q（20 μmo·L^-1）作 用 48 h 对 人 结 直 肠 癌 细 胞DLD-1 存活率的影响,检测化合物2o（0.5、1.0、2.0、5.0、7.5、10.0、12.5、15.0、17.5 μmo·L^-1）作用48 h对人结直肠癌细胞HCT116、RKO和DLD-1存活率的影响;克隆形成实验检测化合物2o（2.5、5.0、10.0 μmo·L^-1）对RKO、DLD-1、HCT116细胞增殖的影响;流式细胞术和 Hoechst染色检测化合物 2o 对细胞凋亡的影响;细胞划痕实验检测化合物 2o 对 DLD-1 和RKO 细胞迁移率的影响;Western blotting 法检测化合物 2o 对 RKO 细胞 p-STAT3、STAT3、骨髓白血病细胞分化蛋白（MCL）-1、生存素（Survivin）、B淋巴细胞瘤-2（Bcl-2）、Bcl-2相关X蛋白（Bax）蛋白表达水平的影响,检测化合物2o对白细胞介素-6（IL-6）刺激下p-STAT3、STAT3蛋白表达水平的影响。结果 化合物2o对DLD-1细胞的杀伤能力较其他化 合 物 强 ; 化 合 物 2o 对 HCT116、 RKO 和 DLD-1 细 胞 的 半 数 抑 制 浓 度 （IC₅₀） 分 别 为 （3.573±0.172）、（8.056±0.458）、（6.226±0.458）μmo·L^-1。与对照组比较,化合物2o明显降低了HCT116、RKO和DLD-1细胞的集落形成能力;显著降低DLD-1和RKO细胞迁移率（P＜0.01、0.001）;明显增加RKO、DLD-1细胞凋亡率;明显增加HCT116和RKO细胞核亮染比例;明显降低p-STAT3、MCL-1、Survivin、Bcl-2蛋白表达,明显升高Bax蛋白表达,对STAT3蛋白表达无明显影响。与对照组比较,IL-6刺激的模型组p-STAT3蛋白表达明显升高,STAT3蛋白表达无明显变化;与模型组比较,随着化合物2o浓度的升高,p-STAT3蛋白表达明显降低,STAT3蛋白表达无明显变化。结论 化合物2o可能通过下调STAT3信号通路发挥抗人结直肠癌作用。     

Depletion in vitro of mitochondrial glutathione in rat hepatocytes and enhancement of lipid peroxidation by adriamycin and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)

Treatment of isolated rat hepatocytes with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and adriamycin (ADR) produced a complete depletion of cellular glutathione accompanied by a significant increase in lactate dehydrogenase (LDH) leakage. Separation of the mitochondrial and cytoplasmic pools of glutathione by digitonin disruption showed that, although BCNU, a specific inhibitor of glutathione, completely depleted the cytoplasmic pool of glutathione, the mitochondrial supply was not entirely expended and LDH leakage was only moderately stimulated. Only after depletion of the mitochondrial supply of glutathione by ADR and BCNU did LDH leakage increase markedly. Measurement of lipid peroxidation, by monitoring malondialdehyde through the thiobarbituric acid procedure, showed that malondialdehyde accumulated more extensively and at a rate mirroring release of LDH from ADR/BCNU treated cells. The time of increase in LDH leakage and malondialdehyde production corresponded to the time of depletion of mitochondrial glutathione to less than 10% of the initial pool size. No such increase in LDH leakage was observed with BCNU or ADU treatment alone or when aminopyrine, an inhibitor of lipid peroxidation, was included. Aminopyrine was found to prevent, in a dose-dependent manner, both LDH leakage and malondialdehyde production stimulated by ADR/BCNU treatment. The protective effect peaked at 5 mM aminopyrine, and higher concentrations produced significant LDH leakage exhibiting LDH release kinetics different than those observed with ADR/BCNU. Although aminopyrine had no effect on the rate or extent of cytoplasmic glutathione depletion by ADR/BCNU treatment, the mitochondrial pool was conserved significantly in those cells protected by aminopyrine. These data suggest that enhanced hepatocyte damage observed after treatment with a combination of ADR and BCNU versus BCNU or ADR alone is due to the extensive depletion of mitochondrial glutathione supported by ADR after glutathione reductase inhibition. Further, enhancement of lipid peroxidation is strongly implicated in the mechanism of adriamycin toxicity.     

R-(+)-[2,3-Dihydro-5-methyl-3-(4-morpholinylmethyl)-pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphtalenylmethanone (WIN-2) ameliorates experimental autoimmune encephalomyelitis and induces encephalitogenic T cell apoptosis: partial involvement of the CB(2) receptor

Many reports have shown that cannabinoids might be beneficial in the symptomatic treatment of multiple sclerosis (MS). We have investigated the therapeutic properties of the non-selective cannabinoid receptor agonist WIN-2 as a suppressive drug in the experimental autoimmune encephalomyelitis (EAE) model of MS. In the passive variety of EAE, induced in Lewis rats by adoptive transfer of myelin-reactive T cells, WIN-2 ameliorates the clinical signs and diminishes the cell infiltration of the spinal cord. Due to the involvement of cannabinoids in the regulation of cell death and survival, we investigated the effects of WIN-2 on the encephalitogenic T cell population. WIN-2 induced a profound increase of apoptosis in a dose- and time-dependent manner. The potential involvement of cannabinoid receptors (CB) was investigated by encephalitogenic T cell stimulation in the presence of the CB(1) (SR141716A) and CB(2) (SR144528) antagonists, pertussis toxin (PTX) and the inactive enantiomer WIN-3. WIN-2-induced apoptosis was partially blocked by SR144528 and PTX, whereas, WIN-3 only exerted a mild effect on cell viability. These results point to the partial involvement of CB(2) receptor together with other receptor-independent mechanism or by yet unknown cannabinoid receptors. Moreover, WIN-2 induced the extrinsic pathway of apoptosis, as shown by caspase-10 and -3 activation. These results suggest that cannabinoid-induced apoptosis of encephalitogenic T cells may cooperate in their anti-inflammatory action in EAE models. The partial involvement of CB(2) receptors in WIN-2 action may open new therapeutic doors in the management of MS by non-psychoactive selective cannabinoid agonists.     

3,4-二氯-N-甲基-N-[反式-2-(1-△3-吡咯啉基)环己基]-苯乙酰胺盐酸盐的合成及其镇痛活性的研究

3, 4-Dichloro-N-methyl-N-[trans-2- (1-△³-pyrrolinyl)-cyclohexyl]-benzenacetamide hydrochloride (K-Ⅱ) was synthesized from N-methyl-7-azabicyclo [4.1.0] heptane by treatment with 2,5-dihydropyrrole to give N-[trans-2(1-△³-pyrrolinyl)-cyclohexyl]-N-methylamine which was amidated with 3,4-dichlorophenyl-acetic acid. K-Ⅱ is an analogue of U-50488 H(K-Ⅰ), a known kappa receptor agonist.The results of animal tests showed that K-Ⅱ is 3 times as potent as K-Ⅰ as an analgesic in the mouse hot plate test and 5 times in the mouse writhing test and that the affinity of K-Ⅱ for kappa receptor may be higher than that of K-Ⅰ. The general behavioural effects of these two agents are similar in mice.     

血吸虫病化学治疗的研究——ⅩⅪⅤ.5-[2-(5-硝基呋喃基-2)-1-取代乙烯基]-1,3,4-噁二唑酮及其1,3,4-噁二唑衍生物的合成

本文报道硝基呋喃乙烯基-1,3,4-噁二唑及其酮类衍生物44个的合成。关键中间体α-取代β-(5-硝基呋喃基-2)丙烯酰彤魄仿照文献已知方法制备的,然后分别与光气或溴化腈作用生成相应的1,3,4-噁二唑衍生物Ⅰ,Ⅱ。经感染日本血吸虫病小白鼠的预防和治疗试验,发现化合物Ⅰ₁具有显著的抗血吸虫作用,并试用于家犬的血吸虫病,证明有一定的疗效。但效果不及呋喃丙胺,故未作临床观察。     

对羟吡啶甲基腺苷在大鼠输精管A1与非A1受体作用

为进一步研究对羟吡啶甲基腺苷(HPMA)受体作用特点,用离体大鼠前列腺端输精管,比较了它与A1受体特异性激动剂环己烷基腺苷(CHA)作用异同。结果表明,HPMA有非A1受体样突触后抑制作用,能剂量依赖性地降低外源性PE,NE,ACh引起的输精管收缩反应;在场刺激下它优先作用于突触前;高剂量的HPMA(10^-5mol·L^-1)不仅可完全抑制场刺激引起的输精管收缩反应,同时还使组织对外源性ACh的反应性降低,是突触前抑制和突触后抑制的共同结果。提示HPMA在大鼠输精管同时具有突触前A1受体和突触后非A1受体作用。