Triterpenoid saponins from Androsace umbellata and their anti-proliferative activities in human hepatoma cells

Two new triterpenoid saponins, along with five known ones, were isolated from the EtOH extract of the whole plants of Androsace umbellata. The structures of the new triterpenoid saponins were identified as 3- O-[ beta- D-xylopyranosyl-(1-->2)- beta- D-glucopyranosyl-(1-->4)-[ beta- D-glucopyranosyl-(1-->2)]- alpha- L-arabinopyranosyl]-3 beta-hydroxy-13 beta,28-epoxy-16-oxo-oleanan-30-al ( 1) and 3- O- beta- D-xylopyranosyl-(1-->2)- beta- D-glucopyranosyl-(1-->4)- alpha- L-arabinopyranosyl-3 beta-hydroxy-13 beta,28-epoxy-16-oxo-oleanan-30-al ( 2) on the basis of their spectral and chemical properties. All these compounds showed significant cytotoxic activities in human hepatoma cells.     

In vitro toxicity screening of magnetite nanoparticles by applying mesenchymal stem cells derived from human umbilical cord lining

Despite the growing interest in nanoparticles (NPs), their toxicity has not yet been defined and the development of new strategies and predictive models are required. Human stem cells (SCs) offer a promising and innovative cell‐based model. Among SCs, mesenchymal SCs (MSCs) derived from cord lining membrane (CL) may represent a new species‐specific tool for establishing efficient platforms for primary screening and toxicity/safety testing of NPs. Superparamagnetic iron oxide NPs, including magnetite (Fe₃O₄NPs), have aroused great public health and scientific concerns despite their extensive uses. In this study, CL‐MSCs were characterized and applied for in vitro toxicity screening of Fe₃O₄NPs. Cytotoxicity, internalization/uptake, differentiation and proliferative capacity were evaluated after exposure to different Fe₃O₄NP concentrations. Data were compared with those obtained from bone marrow (BM)‐MSCs. We observed, at early passages (P3), that: (1) cytotoxicity occurred at 10 μg/mL in CL‐MSCs and 100 μg/mL in BM‐MSCs (no differences in toxicity, between CL‐ and BM‐MSCs, were observed at higher dosage, 100‐300 μg/mL); (2) cell density decrease and monolayer features loss were affected at ≥50 μg/mL in CL‐MSCs only; and (3) NP uptake was concentration‐dependent in both MSCs. After 100 μg/mL Fe₃O₄NP exposures, the capacity of proliferation was decreased (P5‐P9) in CL‐MSCs without morphology alteration. Moreover, a progressive decrease of intracellular Fe₃O₄NPs was observed over culture time. Antigen surface expression and multilineage differentiation were not influenced. These findings suggest that CL‐MSCs could be used as a reliable cell‐based model for Fe₃O₄NP toxicity screening evaluation and support the use of this approach for improving the confidence degree on the safety of NPs to predict health outcomes.     

In vitro DNA damage by Casiopeina II-gly in human blood cells

A variety of metal ions have biological functions, and many researchers have not actively investigated copper compounds, based on the assumption that endogenous metals might be less toxic. In the present study, we used a dual fluorochrome method and a single cell gel electrophoresis (SCGE) assay at pH?>?13 to evaluate the cell viability and DNA damage induced by a copper-based antineoplastic drug, Casiopeina II-gly®, at concentrations of 1.04, 2.08, 4.17, 8.35 or 16?μg/mL in human peripheral-blood leukocytes in vitro. We observed that Casiopeina II-gly® reduced cell viability at high concentrations (8.35 and 16?μg/mL) and induced DNA damage characterized by single-strand breaks and alkali labile sites at several concentrations from 2.08 to 16?μg/mL. This chemical clearly affected DNA migration in a concentration- and time-dependent manner and induced genotoxic effects in few minutes (>20?min), at which point the genotoxicity was followed by cytotoxicity.     

In vitro uptake of salicylate by human red blood cells

Distribution and binding properties of sodium salicylate to human red blood cells were studied under various experimental conditions. The effect of tonicity and hemolysis on the steady state level of the drug within the human red blood cells were accounted for in this study. When the washed cells were suspended in normal saline solution, the drug was so rapidly permeated into red cells. Since the pH of the system forces nearly complete ionization of the drug, ionic diffusion through aqueous pores is thought to be the mode of salicylate transport. Human red cell binding capacity and association constant for salicylate were estimated. This work supports the view that the red cells act as an important reservior of salicylate.     

Anti-proliferative activity of fenretinide in human hepatoma cells in vitro and in vivo

N-(4-hydroxyphenyl)-retinamide (fenretinide) is a synthetic derivative of all-trans-retinoic acid and induces apoptosis in several cancer cell lines. We determined the anti-cancer activity of fenretinide using human hepatoma cell lines, Bel-7402, HepG2 and Smmc-7721. An in-vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that fenretinide exhibited growth inhibition in these cell lines, with IC50 values ranging from 13.1 to 15.5 micromol/l. In Bel-7402 cells, apoptosis with 15 micromol/l fenretinide for 0 and 48 h was 3 and 48%, respectively. In-vivo studies using the Bel-7402 xenografted athymic mouse model showed tumor inhibition rates ranging from 37.2 to 57.2%, with fenretinide administration once per 3 days at the rate of 25-100 mg/kg. Western blot analysis further showed down-regulation of procaspase-3, X-linked inhibitor of apoptosis protein and poly(ADP-ribose) polymerase cleavage in Bel-7402 cells treated with 15 mumol/l fenretinide for 48 h. Overexpression of p53 was observed in a time-dependent manner, along with a decrease in the Bcl-2/Bax ratio. Depolarized mitochondrial membranes were found in fenretinide-induced apoptotic cells, in a time-dependent manner. We conclude that fenretinide effectively inhibits the proliferation of Bel-7402, both in vitro and in vivo. Both procaspase-3 and p53-mediated apoptotic pathways are involved in its potent anti-cancer activity.     

Reproducible chemical-induced changes in gene expression profiles in human hepatoma HepaRG cells under various experimental conditions

The use of in vitro human liver cell models is an attractive approach in toxicogenomic studies designed to analyze gene expression changes induced by a toxic chemical. However, in such studies, reliability, reproducibility and interlaboratory concordance of microarrays, as well as the choice of the most suitable cell model, remain a matter of debate. This work was aimed at evaluating the robustness of microarray technologies and the suitability of the highly differentiated human HepaRG cell line in the investigation of gene expression changes induced by a toxic compound in human liver. The influence of various experimental conditions including cell cultures grown at different test sites, different generations of microarrays, RNA analysis platforms and softwares, was tested on gene expression profiles induced by a 20 h treatment with an 8 mM concentration of phenobarbital as the toxic compound. As many as 1099 genes (p-value < 0.01 and 1.5-fold-change), representing 74% and 30% of the signature genes detected with Agilent 22 and 44K pangenomic microarrays, respectively, were shown to be modulated in common in six independently performed experiments. The most modulated genes included both those known to be regulated by phenobarbital, such as cytochromes P450 and membrane transporters, and those involved in oxidative stress, inflammation and apoptosis, typifying a toxic insult. These data provide strong support for the use of a toxicogenomic approach for the in vitro prediction of chemical toxicity, and for the choice of human HepaRG cells as a promising model system for human hepatotoxicity testing.     

Use of human cumulus granulosa cells for in vitro screening of reproductive toxicants

We investigated the possibility that human granulosa cells from the cumulus mass obtained during human in vitro fertilization/embryo transfer (IVF/ET) might be useful for screening of potential reproductive toxicants in vitro. The cumulus granulosa cells detached from the zona pellucida after fertilization were allowed to spontaneously adhere to the incubation dish following transfer (removal) of the embryo. These cumulus cells survived in culture for at least four additional days, appeared on simple inspection to be morphologically normal luteinized granulosa cells, and produced large amounts of progesterone (P) over the culture interval. Production gradually declined during culture in the absence of human chorionic gonadotropin (hCG); however, inclusion of hCG (100 ng/mL) in the medium maintained P production at control (day 1) levels. Introduction of estrogenic agents previously shown to suppress P production in porcine or human culture systems using mural granulosa cells showed comparable effects in this human cumulus cell system. 17 beta-estradiol (10(-5) M), clomiphene citrate (10(-5) M), and o,p-DDT (10(-5)) significantly inhibited hCG-supported P production by human cumulus cells in vitro. This system has the advantages that (1) human cumulus granulosa cells are readily available from IVF/ET programs, (2) the techniques for maintaining the cells in culture are extremely simple, (3) a marker of highly differentiated granulosa cell function (P production) can be reliably measured, and (4) the cells respond predictably like other comparable granulosa cell systems. We conclude that human cumulus cells are a readily available and useful resource for in vitro screening of potential female reproductive toxicants.     

杠柳毒苷体外抑制肝癌细胞和乳腺癌细胞增殖的实验研究

目的探讨杠柳毒苷在体外对人乳腺癌MDA—MB．468细胞和人肝癌HepG2细胞增殖的影响。方法MTT法观察杠柳毒苷对人乳腺癌MDA-MB-468细胞和人肝癌HepG2细胞增殖的抑制作用,流式细胞术观察杠柳毒苷对两种肿瘤细胞的细胞增殖周期作用。结果与对照组比较,杠柳毒苷能明显抑制两种肿瘤细胞的增殖,其抑制率与药物浓度和作用时间呈正相关。流式细胞仪检测发现,杠柳毒苷对乳腺癌MDA-MB-468细胞和肝癌HepG2细胞持续作用24h后,可以使GdG1期细胞增多,G2／M期细胞减少。结论杠柳毒苷具有抑制乳腺癌MDA-MB-468细胞和肝癌HepG2细胞增殖的作用,并可将乳腺癌MDA-MB-468细胞和肝癌HepG2细胞的细胞生长周期阻滞在G0／G1期。     

In vitro inhibition by gossypol of oxidoreductases from human tissues

The effect of gossypol, a polyphenolic compound with antifertility action on human males, has been investigated on the following oxidoreductases purified from human tissues: lactate dehydrogenase (EC 1.1.1.27) isozymes 1 or B4 from heart, 5 or A4 from liver and X or C4 from spermatozoa; malate dehydrogenase (EC 1.1.1.37) mitochondrial and "soluble" isozymes from heart and NADP-glutamate dehydrogenase (EC 1.4.1.4) from liver. Gossypol proved to be a powerful inhibitor of the six enzymes studied. For all of them, inhibition was of the competitive type with respect to the coenzyme and non-competitive in relation to substrate. The lowest ki values were shown for lactate dehydrogenase isozyme 1 or B4 and for the two isozymes of malate dehydrogenase. Results did not show selectivity of gossypol for the sperm-specific isozyme X or C4 of lactate dehydrogenase.     

Cytotoxic effects of procyanidins from Castanea mollissima Bl. shell on human hepatoma G2 cells in vitro

Significant cytotoxic effects of procynadins from chestnut (Castanea mollissima Bl.) shell (CSPC) on human hepatoma G2 (HepG2) cells were found in vitro. CSPC could inbibit HepG2 proliferation in a dose-dependent manner (100–400 μg/mL), arrest cell cycle in the G₀/G₁ phase, induce apoptosis and trigger necrosis of HepG2. Proapoptotic effect of CSPC was evidenced by nuclear condensation, internucleosomal DNA fragmentation. Treatment of HepG2 cells with CSPC caused a loss of mitochondrial membrane potential and stimulated reactive oxidative species (ROS) generation. These results suggested CSPC could trigger apoptosis and necrotic cell death in HepG2 cell, which might be associated with ROS generation through the mitochondria-dependent signaling way.     

Variation in drug-metabolizing enzyme activities during the growth of human Hep G2 hepatoma cells

1. The activities of several drug-metabolizing enzymes change during the growth cycle (exponential growth to confluence) of Hep G2 cells in culture. As the rate of cell growth slowed down (days 7 to 10 after passage) the activities of ethoxy- and methoxy-resorufin O-dealkylase and of NADPH cytochrome c- and NADH cytochrome b5-reductase increased. In contrast, the O-dealkylations of pentoxy- and benzyloxy-resorufin did not change significantly during culture. 2. UDP-glucuronyltransferase activities also showed substrate-dependent alterations with time in culture. In contrast, glutathione-S-transferase activity remained constant despite a decline in the intracellular reduced glutathione content. 3. Epoxide hydrolase activity altered throughout time in culture, with an initial decrease in activity followed by a marked increase between days 7 and 10 after passage. 4. These results indicate the importance of standardizing the protocol with regard to the timing of experiments within the growth period of the cells when using hepatoma cell lines for assessing the metabolism and cytotoxicity of chemicals.     

In vitro cytotoxicity to human cells in culture of some phenolics from olive oil

The neutral red in vitro cytotoxicity assay was used to evaluate the comparative responses of human cells isolated from tissues of the oral cavity to olive oil phenolics. The cell lines used included normal gingival fibroblasts, immortalized, nontumorigenic gingival epithelial cells, and carcinoma cells from the salivary gland. No differences in the relative sensitivities to the phenolics amongst the three cell types were noted. In general, for all cell types, the sequence of increasing cytotoxicity was: oleuropein aglycone>oleuropein glycoside, caffeic acid>o-coumaric acid>cinnamic acid>tyrosol, syringic acid, protocatechuic acid, vanillic acid. Cytotoxicity was noted only at phenolic concentrations far exceeding those attainable after habitual consumption, thus indicating that consumption of phenol-rich olive oil is safe.     

In vitro prediction and in vivo verification of enantioselective human tofisopam metabolite profiles.

In vitro studies were conducted to elucidate the metabolic profiles of and the enzymes responsible for the metabolism of (R)- and (S)-tofisopam (1-(3,4-dimethoxyphenyl)-5-ethyl-7,8-dimethoxy-4-methyl-5H-2,3-benzodiazepine). Large differences were observed between the two enantiomers. The major metabolite in incubations of 500 ng/ml (approximately 1.3 microM) (R)-tofisopam in human liver microsomes corresponded to demethylation of the methoxy group at the 4-position of the phenyl ring (M3). Incubating (R)-tofisopam with recombinant cytochrome P450 (P450) or with human liver microsomes and isoform-selective P450 chemical inhibitors indicated that M3 was primarily catalyzed by CYP2C9. Similar incubations with S-tofisopam indicated that the primary metabolite was due to demethylation of the methoxy group at the 7-position of the benzodiazepine ring (M1), and this reaction was catalyzed primarily by CYP3A4. The primary metabolites of both enantiomers were further demethylated to form a common didemethylated metabolite (M5) where the methoxy groups at positions 4 and 7 are demethylated. Analysis of plasma and urine samples from human clinical trials confirmed the in vitro observations. Subjects orally treated with 200 mg b.i.d. (R)-tofisopam had a 2-h M1/M3 plasma ratio of 1:29 and a ratio of 1:123 in urine, whereas patients orally administered (S)-tofisopam at 150 mg/kg t.i.d. had opposite M1 to M3 ratios of 8:1 in plasma and 6:1 in urine.     

In vitro inhibition screening of human hepatic P 450 enzymes by five angiotensin-II receptor antagonists

Objective: Metabolic interactions at the level of drug-metabolising enzymes are important for drug therapy. We investigated potential interactions of losartan, irbesartan, valsartan, eprosartan and candesartan with cytochrome P ₄₅₀ (CYP) enzymes in human liver microsomes. Methods: In incubations with human liver microsomes in vitro, the inhibitory potency of angiotensin-II receptor antagonists (sartans) on CYP-specific model activities were compared by measuring the IC₅₀ and, with respect to more potent inhibition, K _i values. Results: None of the five sartans inhibited CYP2A6-, CYP2D6- or CYP2E1-associated activities (coumarin 7-hydroxylation, dextromethorphan O-demethylation and chlorzoxazone 6-hydroxylation, respectively) to any significant extent. Losartan and irbesartan inhibited the CYP2C9-associated tolbutamide methylhydroxylation more potently (K _i values 4.1 μM and 24.5 μM), than valsartan, candesartan or eprosartan (K _i values 135 μM, 155 μM and >1000 μM, respectively). Losartan and irbesartan inhibited CYP1A2- and CYP3A4-associated activities (ethoxyresorufin O-deethylation and testosterone 6β-hydroxylation) with relatively weak affinities (IC₅₀ values between 200 μM and 500 μM). CYP2C19-associated S-mephenytoin 4′-hydroxylation activity was inhibited by losartan (IC₅₀ value 138 μM) and much less or not at all by the other sartans tested. Conclusion: All sartans except eprosartan have at least some affinity for CYP2C9, but only losartan has an affinity for CYP2C19. Losartan and irbesartan have modest affinity for CYP1A2 and CYP3A4. This would suggest that the theoretical potential for drug interactions is likely to be quite low, with the possible exceptions of losartan and irbesartan for CYP2C9. Based on these findings, further studies on the interaction potential of losartan and irbesartan are warranted. Received: 27 October 1999 / Accepted in revised form: 10 February 2000     

Biological activities of a major protein secreted from the rat seminal vesicles after structural modification catalyzed by transglutaminase in vitro

The immunosuppressive, anti-inflammatory and anti-thrombotic properties of SV-IV, a major protein secreted from the epithelium of rat seminal vesicles, were investigated after transglutaminase-catalyzed covalent incorporation of two molecules of spermidine (Spd) into the protein at the level of Gln-9 and Gln-86. The modified molecular form of the protein (Spd₂-SV-IV) showed a more marked inhibitory activity on Con A-induced lymphocyte blastogenesis in comparison with the native protein, whereas no differences in the ability to inhibit the mixed lymphocyte reaction and to decrease the rat epididymal sperm immunogenicity were found between modified and native SV-IV. Spd₂-SV-IV was also less effective than native SV-IV to inhibit platelet aggregation induced in vivo by different thrombogenic agents. In contrast, superimposable inhibitory tracings were observed in the in vitro platelet aggregation experiments performed with the two different molecular forms on the protein. Finally, Spd₂-SV-IV was shown to retain unchanged the anti-inflammatory activity of native SV-IV.     

In vitro metabolism of ciclesonide in human nasal epithelial cells

Ciclesonide, a corticosteroid in development for allergic rhinitis, is converted to the pharmacologically active metabolite, desisobutyryl-ciclesonide (des-CIC), and des-CIC is subsequently esterified with fatty acids. Various experiments were performed to investigate ciclesonide metabolism in human nasal epithelial cells (HNEC). Human nasal epithelial cells were incubated with (a) 0.1 microM ciclesonide for 1 h and medium without ciclesonide for up to 24 h, (b) esterase inhibitors for 0.5 h followed by 5 microM ciclesonide for 6 h, or (c) 1 microM des-CIC for 6 h followed by medium without des-CIC for up to 24 h. Ciclesonide, des-CIC and des-CIC fatty acid conjugate concentrations were determined by high-performance liquid chromatography with tandem mass spectrometry. The amount of ciclesonide in HNEC decreased approximately 93-fold from 0.5 to 24 h. In contrast, des-CIC was present at constant levels throughout the post-treatment period. Furthermore, fatty acid conjugates of des-CIC were retained in HNEC up to 24 h post-treatment. Carboxylesterase and cholinesterase inhibitors decreased ciclesonide metabolism > or =50%. The total amounts of des-CIC fatty acid conjugates decreased and the extracellular amounts of des-CIC increased with time. In conclusion, ciclesonide was rapidly converted to des-CIC by carboxylesterases and cholinesterases, and des-CIC underwent reversible fatty acid conjugation in HNEC.     

In vitro dosimetry analyses for acrolein exposure in normal human lung epithelial cells and human lung cancer cells

Establishing accurate dosimetry is important for assessing the toxicity of xenobiotics as well as for comparing responses between different test systems. In this study, we used acrolein as a model toxicant and defined the concentration-response relationships of the key adverse responses in normal human bronchial epithelial (NHBE) cells and human mucoepidermoid pulmonary carcinoma (NCI-H292) cells. Direct trace analysis of intracellular free acrolein is extremely challenging, if not impossible. Therefore, we developed a new method for indirectly estimating the intracellular uptake of acrolein. A 10-min treatment was employed to capture the rapid occurrence of the key alkylation reactions of acrolein. Responses, including protein carbonylation, GSH depletion, and GSH-acrolein (GSH-ACR) adduct formation, were all linearly correlated with acrolein uptake in both cell types. Compared to the NCI-H292 mucoepidermoid carcinoma cells, NHBE cells were more sensitive to acrolein exposure. Furthermore, results from the time-course studies demonstrated that depletion and conjugation of GSH were the primary adverse events and directly associated with the cytotoxicity induced by acrolein. In summary, these data suggest that cell susceptibility to acrolein exposure is closely associated with acrolein uptake and formation of GSH-ACR adducts. The dosimetric analysis presented in this study may provide useful information for computational modeling and risk assessment of acrolein using different test systems.     

Development of an in vitro screening method for evaluating decontamination of sulfur mustard by reactive dermal formulations

New barrier creams known as topical skin protectants (TSPs) recently have been formulated and demonstrated to be effective in delaying skin penetration of the blistering warfare agent sulfur mustard (HD). To further inactivate or neutralize HD, compounds that react with the toxic agent must be incorporated in the formulations, which then become reactive topical skin protectants (rTSPs). Specific and fast screening methods are necessary to assess the decontaminating activity of rTSPs. A headspace sampling technique in conjunction with thermal desorption and gas chromatography-mass spectrometry was evaluated as a potential screening method. A lower detection limit of 1 ng and a coefficient of variation of <20% were observed for the repetitive measurements of residual HD. Using this method, we evaluated a candidate rTSP. The percentage recovery of HD applied to the rTSP decreased by 35% over a 20-min time period compared with a non-rTSP. The candidate formulation showed an instant decontamination of the HD simulant dibutyl sulfide (decontamination was achieved in 2 s). The instrument set-up has the potential to accommodate multiple samples and can be automated. The method can be extended also to test reactive dermal formulations with toxic organophosphorus compounds.