Detection of genotoxicity in fried bacon by the Salmonella/mammalian microsome mutagenicity assay

The potential for mutagen formation in fried bacon and the possible reduction or elimination of this hazard was examined in the Salmonella/mammalian microsome mutagenicity assay using Salmonella typhimurium strain TA98. Alkaline dichloromethane extracts were prepared from green pork bellies, commercial bacon (nitrite-treated and nitrite-free), and pilot-plant bacon (nitrite-free). When fried, all forms of bacon and the green belly samples gave positive mutagenic responses with the plate-incorporation technique. Unfried samples were not mutagenic. Aroclor-activated rat-liver S-9 fractions plus NADPH were essential to demonstrate a mutagenic response. When the frying temperature was held constant (171°C) maximum mutagen formation was observed in samples fried for 6 min; when samples were fried for 6 min a mutagenic response which increased with temperature, in a linear manner, was observed at temperatures above 125°C. Volatile nitrosamines were not detected in the bacon samples. The data indicate the generation of one or more mutagens in fried bacon and green pork belly, the levels of which can be reduced by decreasing heating temperature and/or time.     

山茱萸二氯甲烷溶剂萃取部位对两种细胞影响的研究

目的研究山茱萸二氯甲烷部位对巨噬细胞及人胚肺细胞的影响。方法采用MTT法对比二氯甲烷部位给药组和空白对照组之间OD值的差异,观察药物对细胞的影响。结果巨噬细胞给药组与对照组OD值有显著性差异,人胚肺细胞给药组与模型组之间有显著性差异。结论山茱萸二氯甲烷部位可增强巨噬细胞和人胚肺细胞免疫作用,保护H2O2造模损伤的人胚肺细胞。     

二氯甲烷遗传毒性的体外实验研究

[目的]探讨二氯甲烷(DCM)对DNA的损伤作用。[方法]应用吸收光谱移动法观察不同浓度的DCM(2.0、3.0、4.0、5.0、6.0、7.0μg/μl)与小牛胸腺DNA的加合作用;应用溴乙锭荧光法对不同浓度的DCM(每30μgDNA分别为200、300、400、500、600、700μg)引起的DNA交联作用。[结果]加入2.0~7.0μg/μl的DCM后,DNA的紫外最大吸收峰普遍发生长移(与阴性对照组比较,P<0.05),而且存在剂量-反应关系;每30μg小牛胸腺DNA用200~700μg的DCM直接染毒,DNA交联率由5.53%上升至17.63%,并且具有一定的剂量-反应关系(r=0.979,P<0.05)。[结论]表明DCM能够与小牛胸腺DNA发生加合作用和交联生成作用。     

气相色谱法测定达比加群酯中10种溶剂的残留

目的：建立气相色谱法检测达比加群酯中10种残留溶剂。方法：以Rtx-1（60 m×0.32 mm×1.0μm）极性毛细管柱程序升温,以氮气为载气,FID 为检测器,进样口温度为 200℃,检测器温度为 250℃,对达比加群酯中 10种残留溶剂（甲醇、乙醇、乙酸乙酯、丙酮、二氯甲烷、正己烷、四氢呋喃、异辛烷、吡啶和甲苯）进行测定。结果：各残留溶剂组分均能被良好分离,各溶剂线性关系良好,精密度 RSD 均不超过 3.50%,平均回收率为 96.0%~105.0%。结论：本文建立的方法可用于达比加群酯中残留溶剂的测定。     

Biotransformation of several structurally related 2B compounds to reactive metabolites in the somatic w/w+ assay of Drosophila melanogaster

Biotransformation of several structurally related 2B compounds to reactive metabolites was evaluated in the somatic w/w+ assay of Drosophila melanogaster. Chemicals tested were the dichlorinated alkanes dichloromethane (DCM), 1,2-dichloroethane (DCE), and 1,3-dichloropropane (DCP); the thiouracil derivatives 5-methyl, 2-thiouracil (5M2TU), 6-methyl, 2-thiouracil (6M2TU), and 5-propyl, 2-thiouracil (5P2TU); and the plastic monomer styrene (STY) and its metabolite styrene 7,8-oxide (SO). The tester strains used consisted of one wild-type insecticide-susceptible (IS) laboratory strain (Leiden-S, ST), and two insecticide-resistant (IR) strains (Hikone-R,HK, and Haag-R, HG). The latter have high cytochrome P450-dependent bioactivation capacities. Drosophila larvae heterozygous for the wild-type report gene w+ were exposed chronically to at least three different exposure doses of each compound. A total of 53,694 eyes were analyzed. A positive genotoxic activity was obtained for DCM and for 6M2TU at all exposure doses and genotypes analyzed, and for SO in the IR strains HK-R and HG-R. An overall weakly recombinagenic response was shown by DCE and 5M2TU. The chemicals DCP, 5P2TU, and STY proved to be overall negative in IR as well as in IS strains, and SO was negative in the standard stock. Biotransformation mediated by cytochrome P450 monoxigenases to reactive metabolites is discussed. Environ. Mol. Mutagen. 31:390–401, 1998 © 1998 Wiley-Liss, Inc.     

Antimicrobial and antimalarial activity of Cussonia species (Araliaceae)

Ethnopharmacological relevance

Cussonia species are used in African traditional medicine mainly against pain, inflammation, gastro-intestinal problems, malaria and sexually transmitted diseases.

Aim of the study

To summarise ethnomedicinal uses of Cussonia and to find scientific evidence in support of selected main uses.

Materials and methods

Using the minimum inhibitory concentration (MIC) method, leaves of 13 Cussonia species, Schefflera umbellifera and Seemannaralia gerrardii were tested against pathogens associated with diarrhoea (Enterococcus faecalis and Escherichia coli), sexually transmitted infections (Neisseria gonorrhoeae and Trichomonas vaginalis) and general infectious diseases (Staphylococcus aureus and Pseudomonas aeruginosa). Antimalarial sensitivity was studied using Plasmodium falciparum and the [³H]-hypoxanthine incorporation assay. Cytotoxic effects on a T-cell leukaemia (Jurkat) cell line were determined using the tetrazolium-based cellular toxicity assay.

Results

Methanolic extracts were active against Pseudomonas aeruginosa (MIC of 1.0–1.5 mg/mL), Trichomonas vaginalis (MIC of 0.8–1.3 mg/mL) and Staphylococcus aureus (Cussonia arborea, 1.8 mg/mL). All samples were active against Neisseria gonorrhoeae (MIC of 0.02–0.7 mg/mL). The methanol extract of Cussonia arborea was the most active against Plasmodium falciparum (13.68 μg/mL) and showed anticancer properties (5.60 μg/mL).

Conclusions

The traditional use of Cussonia species to treat sexually transmitted diseases and Plasmodium infections appears to have a scientific basis.     

First small-molecule PROTACs for G protein-coupled receptors: inducing α1A-adrenergic receptor degradation

Proteolysis targeting chimeras (PROTACs) are dual-functional hybrid molecules that can selectively recruit an E3 ubiquitin ligase to a target protein to direct the protein into the ubiquitin-proteasome system (UPS), thereby selectively reducing the target protein level by the ubiquitin-proteasome pathway. Nowadays, small-molecule PROTACs are gaining popularity as tools to degrade pathogenic protein. Herein, we present the first small-molecule PROTACs that can induce the α_1A-adrenergic receptor (α_1A-AR) degradation, which is also the first small-molecule PROTACs for G protein-coupled receptors (GPCRs) to our knowledge. These degradation inducers were developed through conjugation of known α₁-adrenergic receptors (α₁-ARs) inhibitor prazosin and cereblon (CRBN) ligand pomalidomide through the different linkers. The representative compound 9c is proved to inhibit the proliferation of PC-3 cells and result in tumor growth regression, which highlighted the potential of our study as a new therapeutic strategy for prostate cancer.     

Hypotensive and cardio-chronotropic constituents of Tinospora crispa and mechanisms of action on the cardiovascular system in anesthetized rats

Ethnopharmacological relevance

Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa stems decreased the mean arterial blood pressure (MAP) with a transient decrease, followed by an increase in the heart rate (HR) in rats.

Aim of the study

To identify the active components of the Tinospora crispa extract and investigate the mechanisms of action on blood pressure and heart rate in anesthetized rats.

Materials and methods

The active components of Tinospora crispa extract were separated by column chromatography and a preparative HPLC. The effects and mechanisms of the active compounds on blood pressure and heart rate were studied in anesthetized, normal and reserpinized rats in vivo.

Results

5 active compounds: adenosine, uridine, salsolinol, higenamine and tyramine were isolated. Adenosine decreased MAP and HR and this effect was inhibited by DMPX (A_2A adenosine receptor antagonist). Uridine increased MAP and decreased HR and this was inhibited by suramin but not by DMPX. Salsolinol decreased the MAP and HR and this was inhibited by phentolamine but not by ICI-118,551 (β₂-adrenoceptor antagonist) or atropine. In reserpinized rats, salsolinol had a hypertensive effect that was inhibited by prazosin and phentolamine, but not by atenolol, and caused an increase in HR that was inhibited by atenolol, but not by prazosin or phentolamine. Higenamine decreased the MAP with an increase in HR. The hypotensive effect was inhibited by ICI-118,551 or atenolol, whereas the increase in HR was not inhibited by ICI-118,551. Atenolol inhibited the increase in HR at a small dosage of higenamine but potentiated it at a higher dosage. In reserpinized rats, a small dosage of higenamine tended to potentiate the effect but at a higher dosage it caused inhibition. ICI-118,551 significantly inhibited this hypotensive effect. Tyramine caused an increase in MAP and HR and these effects almost disappeared in reserpinized rats.

Conclusions

The results demonstrate that these 5 compounds from Tinospora crispa acted in concert on the cardiovascular system of anesthetized rats. Salsolinol, tyramine and higenamine acted via the adrenoreceptors, whereas uridine and adenosine acted via the purinergic adenosine A₂ and P₂ receptors to decrease blood pressure with a transient decrease of HR followed by an increase.     

Endothelium-dependent and independent vasorelaxation induced by an n-butanolic fraction of bark of Scutia buxifolia Reiss (Rhamanaceae)

Ethnopharmacological relevance

Scutia buxifolia has been widely used in Brazilian folk medicine as an anti-hypertensive agent.We evaluated the vascular effects and mechanism involved in the relaxation of aorta induced by an n-butanolic fraction (BuOH) from Scutia buxifolia.

Materials and Methods

Rat aortic rings precontracted by phenylephrine (1 μM) were exposed to cumulative concentrations (3–3000 μg/ml) of crude extracts or fractions obtained from bark or leaves of Scutia buxifolia. Classical receptor antagonists, channel and enzymatic inhibitors were used to check the mechanisms involved.

Results

The crude extracts of both leaves and bark of Scutia buxifolia, as well as several fractions, were able to induce partial or total relaxation of rat aortic rings. The BuOH fraction of bark of Scutia buxifolia was the most potent in endothelium-intact (E+) preparations, and also induced a partial, but very significant relaxation in endothelium-denuded (E−) vessels. The non-selective nitric oxide synthase inhibitor L-NAME, as well as the soluble guanylate cyclase inhibitor ODQ, vanished the relaxation in E+. In E− preparations, K⁺ channel blockers, such as tetraethylammonium, glibenclamide, 4-aminopyridine, and the large-conductance calcium-activated K⁺ channel blocker iberiotoxin, were able to significantly reduce the maximum relaxation elicited by BuOH fraction.

Conclusion

Our results demonstrated that BuOH fraction obtained from barks of Scutia buxifolia induced both endothelium-dependent and -independent relaxation in rat aortic rings. The endothelium-dependent relaxation is fully dependent on NO/cGMP system, while direct activation of K⁺ channels may explain, at least in part, the endothelium-independent relaxation induced by BuOH fraction of Scutia buxifolia.     

Functional benefits of PLGA particulates carrying VEGF and CoQ10 in an animal of myocardial ischemia

Myocardial ischemia (MI) remains one of the leading causes of death worldwide. Angiogenic therapy with the vascular endothelial growth factor (VEGF) is a promising strategy to overcome hypoxia and its consequences. However, from the clinical data it is clear that fulfillment of the potential of VEGF warrants a better delivery strategy. On the other hand, the compelling evidences of the role of oxidative stress in diseases like MI encourage the use of antioxidant agents. Coenzyme Q₁₀ (CoQ₁₀) due to its role in the electron transport chain in the mitochondria seems to be a good candidate to manage MI but is associated with poor biopharmaceutical properties seeking better delivery approaches.