In vitro mutagenicity of valepotriates

Valepotriates are epoxide-bearing triesters of the monoterpene alcohol 4,7-dimethylcyclopenta-(c)-pyrane isolated from the roots of several Valerianacae species. They are regarded as the main tranquilizing constituents of these drugs.Although the valepotriates valtrate/isovaltrate (VAL) and dihydrovaltrate (DH-VAL) showed a strong alkylating activity against the nucleophilic agent 4-(p-nitrobenzyl)-pyridine (NBP), they were not clearly mutagenic for the strains TA98, TA100, TA1535, and TA1537 of Salmonella typhimurium or for the strains WP2 and WP2 uvrA^– of Escherichia coli in the absence of a metabolic activation system (S9-mix). However, the valepotriates were mutagenic for TA100, WP2 and WP2 uvrA^– at concentrations up to about 1.0 mole/plate when S9-mix was added to the test system. With more than 1 mole/plate the valepotriates were toxic in the presence of a metabolic activation system for all strains tested. The mutagenicity of the valepotriates was inversely related to the protein content of the S9-mix used. The mutagenicity and toxicity of the valepotriates could be inhibited when the S9-mix was preincubated with the esterase inhibitor paraoxon (1 mM) for 5 min before the test compounds and bacteria were added. Therefore, bioactivation of the valepotriates by an enzymatic hydrolysis of their ester groups is considered. This could be proven by activating the valepotriates with purified esterase.Parts of this paper were presented at the Congress, Fortschritte in der Arzneimittelforschung, April 17–20, 1983 in Munich     

Free-base nicotine in tobacco products. Part II. Determination of free-base nicotine in the aqueous extracts of smokeless tobacco products and the relevance of these findings to product design parameters

Reports in the peer-reviewed literature and popular press have alleged that smokeless tobacco product (STP) manufacturers increase the addictiveness of their products by adjusting formulae to increase the relative percentage of nicotine in STP that is not protonated. Such nicotine is more popularly, but incorrectly, known as free-base nicotine (“FBN”) as it is a calculated amount as opposed to a real chemical species in the STP. Some regulators have mandated reporting of FBN as estimated by Henderson–Hasselbalch equation (“HHE”) using the pH-value of an aqueous suspension (or extract) of STP. This is technically incorrect because the HHE is only valid in pure dilute aqueous solution of a single base and its conjugate acid. The aqueous suspensions (or extracts) of STP often contain high concentrations of salts and polymeric anions such as pectate and many other compounds, and there is a molar excess of ammonia over nicotine in some products. These are heretofore-unrecognized sources of error in use of the HHE to estimate relative amount of nicotine that is not protonated results in inaccurate FBN-values. Thus, it is not surprising that attempts to show the relevance of estimated value of FBN in STP to human physiology have failed.     

Mutagenic activity of cytostatic methyl hydrazones with different strains of Salmonella typhimurium

Experiments are performed to ascertain the mutagenic properties of four new cytostatic methyl-hydrazones in the Ames test using different strains of Salmonella typhimurium. As could be demonstrated all four hydrazones are mutagenic per se without a metabolic activation through rat liver microsomes (S-9 fraction). Whereas the -chloroethyl hydrazones B1 and B2 cause a base-pair substitution with the strains TA100 and TA1535 the methyl-hydrazones EB4 and CyB4 both cause base-pair substitution with TA100 and frameshift mutation with TA98. At both strains the mutagenic activity of CyB4 ist powerful. Furthermore, no relation could be detected between the mutagenic properties of the methyl-hydrazones and their alkylating behaviour on 4-(4-nitrobenzyl)-pyridine.     

Chemical and toxicological characterization of commercial smokeless tobacco products available on the Canadian market

Some health experts are recommending that smokers who refuse to quit or refuse to use nicotine replacement therapy (NRT) such as nicotine-containing chewing gum switch to certain types of smokeless tobacco products (STP) such as Swedish snus. Other health experts disagree citing the uncertainty in the composition of commercially available STP, the lack of governmental regulations to ensure that STP advertised to meet certain standards (i.e., GothiaTek^®) do actually meet such standards, and the uncertainty that any STP can provide as safe as alternative to smoking as NRT. One reason for uncertainty is the dearth of detailed chemical and toxicological information on contemporary STP. Unlike the situation with cigarettes, there are few standardized methods for analytical and toxicological studies of STP. Consequently, the objective for this work was to characterize several types of STP available on the Canadian market using the modifications of the Official Health Canada chemical and toxicological methods developed for cigarettes. Moist snuff samples tested had TSNA and B[a]P levels somewhat above the GothiaTek^® standard while samples of Swedish snus, low-moisture snuff, and US-style chewing tobacco did not. Use of in vitro assays to assess STP toxicity was of limited utility in distinguishing product types.     

Mutagenicity of Mouriri pusa Gardner and Mouriri elliptica Martius

Mouriri pusa Gardner and Mouriri elliptica Martius are fruit-bearing plants of the Melastomataceae family, popularly known in Brazil as puçá-preto or jaboticaba-do-cerrado, and they are used in folk medicine for the treatment of gastric ulcers. In this study, we employ the Ames test to assess the mutagenicity of compounds obtained from the leaves of these species. The methanol extract of the M. pusa was mutagenic to the Salmonella typhimurium strains TA98, TA97a and TA100, with or without metabolic activation. The methanol extract of M. elliptica induced mutagenic activity in TA98 when metabolized with S9 fraction and TA97a with and without S9, but with lower mutagenicity index (MI) and potencies values than those for M. pusa. Enriched fractions of flavonoids and tannins of M. pusa were also evaluated and they demonstrated positive mutagenicity. The highest values of MI and potency were obtained with the flavonoid fraction, which contains large amounts of quercetin, quercetin glycosides and myricetin. These compounds are probably related to the mutagenicity observed in the Ames test. The dichloromethane extract was not mutagenic in any of the test conditions employed.     

Influence of fuel properties, nitrogen oxides, and exhaust treatment by an oxidation catalytic converter on the mutagenicity of diesel engine emissions

Particle emissions of diesel engines (DEP) content polycyclic aromatic hydrocarbons (PAH) these compounds cause a strong mutagenicity of solvent extracts of DEP. We investigated the influence of fuel properties, nitrogen oxides (NO _x ), and an oxidation catalytic converter (OCC) on the mutagenic effects of DEP. The engine was fuelled with common diesel fuel (DF), low-sulphur diesel fuel (LSDF), rapeseed oil methyl ester (RME), and soybean oil methyl ester (SME) and run at five different load modes in two series with and without installation of an OCC in the exhaust pipe. Particles from the cooled and diluted exhaust were sampled onto glass fibre filters and extracted with dichloromethane in a soxhlet apparatus. The mutagenicity of the extracts was tested using the Salmonella typhimurium/mammalian microsome assay with tester strains TA98 and TA100. Without OCC the number of revertant colonies was lower in extracts of LSDF than in extracts of DF. The lowest numbers of revertant colonies were induced by the plant oil derived fuels. In three load modes, operation with the OCC led to a reduction of the mutagenicity. However, direct mutagenic effects under heavy duty conditions (load mode A) were significantly increased for RME (TA98, TA100) and SME (TA98). A consistent but not significant increase in direct mutagenicity was observed for DF and LSDF at load mode A, and for DF at idling (load mode E) when emissions were treated with the OCC. These results raise concern over the use of oxidation catalytic converters with diesel engines. We hypothesise that the OCC increases formation of direct acting mutagens under certain conditions by the reaction of NO _x with PAH resulting in the formation of nitrated-PAH. Most of these compounds are powerful direct acting mutagens.     

Bergamottin is a competitive inhibitor of CYP1A1 and is antimutagenic in the Ames test

Grapefruit juice (GJ) is a well known Cytochrome P450 (CYP) inhibitor; CYP3A is one of the most affected subfamily leading to anticarcinogenic and antimutagenic effects when GJ is administered to experimental animals in combination with mutagenic/carcinogenic agents metabolized by CYP3A. Bergamottin, naringin and dihydroxybergamottin are three main constituents contained within GJ and their inhibitory effect against CYP3A4 has been well documented. Reports suggest that CYP3A is not the only one affected but CYP1A and 2B are also affected by GJ. To explore this last possibility in depth we tested the in vitro capacity of bergamottin, naringin and dihydroxybergamottin to inhibit the activity of CYP1A and 2B subfamilies and found that bergamottin showed the strongest inhibitory effect and naringin showed no inhibition at all. Therefore, we decided to biochemically characterize the inhibitory properties of bergamottin. CYP1A1 Supersome® used in this study showed a Km_app = 0.0723 μM and a Vm_app = 6.141 μU/pmol with substrate ethoxyresorufin, and the biochemical characterization of bergamottin CYP1A1 inhibitory effect revealed that it is a competitive inhibitor with a Ki = 10.703 nM. We also confirmed the antimutagenicity of this compound against the mutagenic effect of 3-methylcholanthrene and benzo[a]pyrene in the Ames test.     

Potential of Azadirachta indica against Salmonella typhimurium-induced inflammation in BALB/c mice

Objective:  To evaluate the potential of Azadirachta indica leaf extracts against Salmonella typhimurium-induced inflammation in BALB/c mice. Design:  Qualitative tests of A. indica leaf extracts were conducted for screening of various phytochemicals. The antiinflammatory potential of A. indica leaf extracts on S. typhimurium and its outermembrane proteins (OMPs)-induced inflammation was assessed by hyperalgesic (flicking) response of the mice inflammed paws. The monokines (IL-1α, IL-6 and TNF-α) activities in the culture supernatants of macrophages (infected with bacteria and interacted with OMPs) in the presence or absence of A. indica leaf extracts was assessed by ELISA. Results:  Aqueous and petroleum ether A. indica leaf extracts reduced the inflammation caused by S. typhimurium and its OMPs as assessed by paw flicking response. Petroleum ether A. indica leaf extract was found to be more effective than aqueous A. indica leaf extract. Significantly lower levels of monokines (IL-6 and TNF-α) were also observed in the presence of petroleum ether A. indica leaf extracts than aqueous A. indica leaf extract. These observations may be due to the presence of steroids and triterpenoids observed in petroleum ether extract. Conclusion:  Petroleum ether A. indica leaf extract seems promising to combat S. typhimurium-induced inflammation. Received 6 June 2008; accepted 29 October 2008     

A comparative pH-dissolution profile study of selected commercial levothyroxine products using inductively coupled plasma mass spectrometry

Levothyroxine (T4) is a narrow therapeutic index drug with classic bioequivalence problem between various available products. Dissolution of a drug is a crucial step in its oral absorption and bioavailability. The dissolution of T4 from three commercial solid oral dosage forms: Synthroid^® (SYN), generic levothyroxine sodium by Sandoz Inc. (GEN) and Tirosint^® (TIR) was studied using a sensitive ICP-MS assay. All the three products showed variable and pH-dependent dissolution behaviors. The absence of surfactant from the dissolution media decreased the percent T4 dissolved for all the three products by 26-95% (at 30 min). SYN dissolution showed the most pH dependency, whereas GEN and TIR showed the fastest and highest dissolution, respectively. TIR was the most consistent one, and was minimally affected by pH and/or by the presence of surfactant. Furthermore, dissolution of T4 decreased considerably with increase in the pH, which suggests a possible physical interaction in patients concurrently on T4 and gastric pH altering drugs, such as proton pump inhibitors. Variable dissolution of T4 products can, therefore, impact the oral absorption and bioavailability of T4 and may result in bioequivalence problems between various available products.     

A test strategy for the assessment of additive attributed toxicity of tobacco products

The new EU Tobacco Product Directive (TPD) prohibits tobacco products containing additives that are toxic in unburnt form or that increase overall toxicity of the product. This paper proposes a strategy to assess additive attributed toxicity in the context of the TPD. Literature was searched on toxicity testing strategies for regulatory purposes from tobacco industry and governmental institutes. Although mainly traditional in vivo testing strategies have been applied to assess toxicity of unburnt additives and increases in overall toxicity of tobacco products due to additives, in vitro tests combined with toxicogenomics and validated using biomarkers of exposure and disease are most promising in this respect. As such, tests are needed that are sensitive enough to assess additive attributed toxicity above the overall toxicity of tobacco products, which can associate assay outcomes to human risk and exposure. In conclusion, new, sensitive in vitro assays are needed to conclude whether comparable testing allows for assessment of small changes in overall toxicity attributed to additives. A more pragmatic approach for implementation on a short-term is mandated lowering of toxic emission components. Combined with risk assessment, this approach allows assessment of effectiveness of harm reduction strategies, including banning or reducing of additives.     

染料溶剂红207的体外致突变风险评价

目的 使用基于鼠伤寒沙门氏菌的Ames波动试验和小鼠淋巴瘤细胞（L5178Y）的体外Pig-a基因突变试验评价新型染料溶剂红207的碱基突变风险。方法 不同质量浓度的溶剂红207（0.625~10.000 μg/mL）分别与TA98和TA100混合于96孔培养板,在37℃条件下作用72 h后判断其对突变菌落数的影响。在优化后的体外L5178Y细胞Pig-a基因突变实验中,溶剂红207（2.5~20.0 μg/mL）分别与L5178Y细胞在有或无S9代谢活化条件下作用24 h或4 h,于给药后第8天评价其是否可诱导哺乳动物细胞Pig-a基因的突变频率增加。结果 无和有S9代谢活化条件下,溶剂红207可导致TA98和TA100回复性突变孔数显著增加（P<0.05、0.01、0.001）,且存在浓度效应相关性,代谢活化后增加更为明显。在非S9代谢活化条件下,溶剂红207各浓度组Pig-a基因突变率与阴性对照组比较无显著性差异;在S9代谢活化条件下,溶剂红207质量浓度范围为2.5~20 μg/mL时,可导致Pig-a基因突变率显著增加（P<0.01、0.001）,且存在浓度效应关系。结论 首次使用体外高通量试验方法评价溶剂红207的致突变风险,发现其存在体外致突变性且经I相代谢活化后致突变性进一步增强。     

A comparative study of d- and l-amphetamine on the open field performance of rats

Behavioural effects in the Open Field test following the administration of d- and l-amphetamine were compared in rats. A significant difference was found between the effects of the two isomers on horizontal activity, d-amphetamine alone causing horizontal stereotypy. In both cases dose-response relations were curvilinear. On the other hand, although both isomers produced vertical stereotypy, the dose-response relations were generally monotonic increasing with no signifiacnt differences between isomers. These differential effects on behaviour have been explained on the basis of stereospecificity of adrenergic neurons for amphetamine. The results of the study are consistent with earlier hypotheses that the horizontal and vertical stereotyped behaviours of rats in the Open Field situation are functions of brain noradrenergic and dopaminergic systems, respectively.     

In silico screening of chemicals for bacterial mutagenicity using electrotopological E-state indices and MDL QSAR software

Quantitative structure–activity relationship (QSAR) software offers a rapid, cost effective means of prioritizing the mutagenic potential of chemicals. MDL QSAR models were developed using atom-type E-state indices and non-parametric discriminant analysis. Models were developed for Salmonella typhimurium gene mutation, combining results from strains TA97, TA98, TA100, TA1535, TA1536, TA1537, and TA1538 (n = 3228), and Escherichia coli gene mutation tests WP2, WP100, and polA (n = 472). Composite microbial mutation models (n = 3338) were developed combining all Salmonella, E. coli, and the Bacillus subtilis rec spot test study results. The datasets contained 74% non-pharmaceuticals and 26% pharmaceuticals. Salmonella and microbial mutagenesis external validation studies included a total of 1444 and 1485 compounds, respectively. The average specificity, sensitivity, positive predictivity, concordance, and coverage of Salmonella models was 76, 81, 73, 78, and 98%, respectively, with similar performance for the microbial mutagenesis models. MDL QSAR and discriminant analysis provides rapid and highly automated mutagenicity screening software with good specificity, sensitivity, and coverage that is simpler and requires less user intervention than other similar software. MDL QSAR modules for microbial mutagenicity can provide efficient and cost effective large scale screening of compounds for mutagenic potential for the chemical and pharmaceutical industry.     

Intracellular Visualization of Ampicillin-Loaded Nanoparticles in Peritoneal Macrophages Infected in Vitro with Salmonella typhimurium

Intracellular targeting of ampicillin by means of polyisohexylcyanoacrylate (PIHCA) nanoparticles was studied in murine peritoneal macrophages infected with Salmonella typhimurium. The intracellular distribution of actively endocytosed nanoparticles was visualized by transmission electron microscopy and confocal microscopy. Nanoparticles were either isolated or closely associated with bacteria within phagosomes or phagolysosomes. Thus the potential of ampicillin-loaded nanoparticles .in targeting of intracellular bacteria is demonstrated. Consequently, ampicillin, which usually penetrates into cells at a low level, is directly carried in, when loaded on nanoparticles, and brought into contact with intracellular bacteria.     

Use of in vitro assays to assess the potential antigenotoxic and cytotoxic effects of saffron (Crocus sativus L.)

Saffron is harvested from the dried, dark red stigmas of Crocus sativus L. flowers. It is used as a spice for flavoring and coloring food and as a perfume. It is often used for treating several diseases. We assessed the antimutagenic, comutagenic and cytotoxic effects of saffron and its main ingredients using the Ames/Salmonella test system, two well known mutagens (BP, 2AA), the in vitro colony formation assay and four different cultured human normal (CCD-18Lu) and malignant (HeLa, A-204 and HepG2) cells. When only using the TA98 strain in the Ames/Salmonella test system, saffron showed non-mutagenic, as well as non-antimutagenic activity against BP-induced mutagenicity, and demonstrated a dose-dependent co-mutagenic effect on 2-AA-induced mutagenicity. The saffron component responsible for this unusual comutagenic effect was safranal. In the in vitro colony formation test system, saffron displayed a dose-dependent inhibitory effect only against human malignant cells. All isolated carotenoid ingredients of saffron demonstrated cytotoxic activity against in vitro tumor cells. Saffron crocin derivatives possessed a stronger inhibitory effect on tumor cell colony formation. Overall, these results suggest that saffron itself, as well as its carotenoid components might be used as potential cancer chemopreventive agents.     

Evidence for Neuromodulation of Enteropathogen Invasion in the Intestinal Mucosa

The extensively innervated intestinal mucosa encompasses a vast surface exposed to an array of potentially infectious microorganisms. We investigated the role of enteric nerves in modulating intracellular internalization of a multidrug-resistant Salmonella typhimurium DT104 field isolate in mucosa–submucosa sheets from the porcine ileum, a biomedical model for the human intestine. The effects of transmural electrical stimulation and drugs on intracellular internalization of Salmonella over 90 min was determined by a gentamicin-resistance assay relative to untreated tissues from the same animal serving as controls. The actin inhibitor cytochalasin D reduced internalization of Salmonella, and the mucus-disrupting agent dithiothreitol decreased its mucosal adherence. Transmural electrical stimulation increased, and neuronal conduction blockers saxitoxin and lidocaine decreased Salmonella internalization in stimulated and unstimulated tissues. Furthermore, the alpha-adrenergic/imidazoline receptor ligand phentolamine and the 5-HT₃ receptor antagonist tropisetron decreased internalization in stimulated tissues. Based on these findings, enteric neural activity appears to modulate interactions between the intestinal mucosa and pathogenic bacteria.     

散囊菌属次级代谢产物研究进展

散囊菌属可产生丰富的次级代谢产物,同时,这些次级代谢产物具有丰富的生物活性.本文对散囊菌属次级代谢产物及其生物活性进行综述.     

虎杖饮片指纹图谱的研究及其耐用性考察

目的 为用数据识别虎杖饮片的真伪及评价其质量提供技术支持。方法 采用高效液相色谱(HPLC)法分析虎杖饮片提取物的指纹图谱,色谱柱:Agilent ZORBAX SB-C₁₈柱(4.6 mm×250 mm,5μm);流动相:0.1%甲酸水溶液-乙腈(A-B);梯度洗脱;检测波长306 nm;流速1ml/min;柱温30℃;进样量20μl。结果 成功分离出虎杖饮片提取液中的虎杖苷、白藜芦醇、大黄素、大黄素甲醚等有效成分。结论 该方法稳定有效,具有良好的耐用性,对虎杖饮片的数据识别具有指导意义。     

基于UPLC-LTQ-Orbitrap/MS的姜黄连炮制前后化学成分比较研究

目的 分析姜黄连的化学成分,在物质基础层面探究姜炙对黄连的影响。方法 采用Waters Acquity UPLC BEH C18色谱柱（100 mm×2.1 mm,1.7 μm）,以0.1%甲酸水溶液（A）-乙腈（B）为流动相进行梯度洗脱,利用LTQ-Orbitrap/MS正、负离子模式采集数据,通过高分辨质谱数据解析,对姜黄连的化学成分进行定性分析。结果 黄连、姜黄连和生姜汁中共鉴定出34种化合物,其中归属于黄连25种、姜黄连32种、生姜汁9种;黄连和姜黄连的共有成分25种,黄连姜炙后新增7种姜辣素类物质,均为生姜汁中的成分。结论 黄连姜炙后化学成分发生变化,新增了7种姜辣素类成分,为姜黄连的药效物质基础研究提供参考。     

Is the activation of aflatoxin B1 catalysed by the same form of cytochrome P-450 as that 4-hydroxylating debrisoquine in rat and/or man?

A possible association between the metabolic activation of aflatoxin B₁ (AFB₁) to a mutagen and the 4-hydroxylation of debrisoquine, which shows genetic variation both in man and in the rat, was investigated. Hepatic microsomal fractions from female DA and Fischer rats catalyse, at the same rate, the conversion of AFB₁ to a mutagenic and arylating metabolite, that bound covalently to microsomal proteins. Debrisoquine was without effect on either of these reactions. In contrast, metyrapone did inhibit the mutagenic activation of AFB₁. Microsomal fraction from human liver was also capable of activating AFB₁ to a mutagenic and arylating metabolite. Again, debrisoquine was without appreciable effect on these reactions. In contrast, cimetidine caused profound inhibition of the mutagenic activation of AFB₁. It is concluded that the activation of AFB₁ to a mutagenic, and presumably carcinogenic, metabolite is catalysed by a different form of cytochrome P-450 from that catalysing the 4-hydroxylation of debrisoquine, both in rat and in man.