McKim J.M.,CeeTox Inc.
Critical Reviews in Toxicology
Carrageenan (CGN) has been used as a safe food additive for several decades. Confusion over nomenclature, basic CGN chemistry, type of CGN tested, interspecies biology, and misinterpretation of both in vivo and in vitro data has resulted in the dissemination of incorrect information regarding the human safety of CGN. The issue is exacerbated when mechanistic data obtained from in vitro experiments are directly translated to human hazard and used for risk assessment. This can lead to information that is taken out of experimental context and reported as a definitive effect in humans. In recent years, the use of cell-based models has increased and their ability to provide key information regarding chemical or drug safety is well established. In many instances, these new alternative approaches have started to replace the need to use animals altogether. In vitro systems can be extremely useful for understanding subcellular targets and mechanisms of adverse effects. However, care must be exercised when extrapolating the in vitro findings to in vivo effects. Often, issues such as chemical identity and purity, relevant dose, pharmacokinetic properties, solubility, protein binding, adsorption to plastics, and the use of cell models that are biologically and mechanistically relevant are overlooked or ignored. When this occurs, in vitro findings can provide misleading information that is not causally linked to in vivo events in animals or in humans. To date, there has not been a comprehensive review of the CGN in vitro literature, which has reported a wide range of biochemical effects related to this compound. An extensive effort has been made to evaluate as much of this literature as possible. This review focuses on the in vitro observation, the unique chemistry of CGN, and potential pitfalls of in vitro models used for hazard identification. The discussion of the in vitro studies discussed this review are supported by numerous in vivo studies. This provides a unique opportunity to have both the in vitro and in vivo studies reviewed together. © 2014 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted. Source
Osimitz T.G.,Science Strategies LLC |
Eldridge M.L.,University of Tennessee at Knoxville |
Sloter E.,WIL Research Laboratories LLC |
Welsh W.,UMDNJ Robert Wood Johnson Medical School |
And 5 more authors.
Food and Chemical Toxicology
Eastman Tritan™ copolyester, a novel plastic from Eastman is manufactured utilizing three monomers, di-methylterephthalate (DMT), 1,4-cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) in various ratios. As with most any polymer, the monomers along with the high molecular weight oligomers, whose toxicity is most commonly represented by the monomers, make up the predominate amount of free chemicals available for leaching into the environment and/or foods. In light of the high level of public concern about the presence of endocrine (primarily estrogenic) activity ascribed to certain plastics and chemicals in the environment, Tritan's™ monomers were evaluated using QSAR for binding to the androgen receptor and estrogen receptors (alpha and beta) as well as a battery of in vitro and in vivo techniques to determine their potential androgenicity or estrogenicity. The findings were universally negative. When these data are coupled with other in vivo data developed to assess systemic toxicity and developmental and reproductive toxicity, the data clearly indicate that these monomers do not pose an androgenic or estrogenic risk to humans. Additional data presented also support such a conclusion for terephthalic acid (TPA). TPA is also a common polyester monomer and is the main mammalian metabolite formed from DMT. © 2012 Elsevier Ltd. Source
Koschier F.,Johnson and Johnson Consumer Products Company |
Kostrubsky V.,Vistakon |
Toole C.,CeeTox Inc. |
Food and Chemical Toxicology
The current study investigated the influence of ethanol and ethanol-containing mouthrinses on model chemical permeability in an in vitro oral buccal mucosal construct (EpiOral, ORL-200, MatTek). Innate ethanol transport and metabolism in the tissue construct was also studied. Caffeine flux in buccal tissue was measured after pre-treatment with < 26.9% ethanol or Listerine ® products under conditions modeling a typical mouthwash rinsing. Specifically, a 30s exposure to alcohol products followed by a 10h non-treatment phase and then a second 30s exposure prior to addition of caffeine. At 10min specific intervals, media was collected from the basal part of the tissue insert for HPLC analysis of caffeine. The results demonstrated no increase in caffeine flux due to prior exposure to either ethanol or Listerine ®, and the flux and permeability constants were derived from the linear phase. No cytotoxicity or histopathological effects were observed in these tissues. We also studied the transepithelial transport and metabolism of ethanol in these tissues. Transport of ethanol was concentration-dependent with rate of diffusion proportional to the concentration gradient across the membrane. The potential metabolism of ethanol in the EpiOral construct was addressed by analyzing the remaining level of ethanol after incubation and de novo accumulation of acetaldehyde or acetic acid in culture media. Incubation for 30min incubation resulted in no change in ethanol level up to 2000mM, the highest concentration tested. No acetaldehyde or acetic acid was detected in culture media. In conclusion, ethanol and ethanol-containing mouthrinse treatment modeled after a typical daily mouthrinse pattern had no apparent effect on the permeability of the standard model chemical, caffeine. This exposure also had no effect on the viability of the tissue construct or histopathology, and uptake of ethanol was rapid into the tissue construct. © 2011 Elsevier Ltd. Source
Lapchak P.A.,Cedars Sinai Medical Center |
McKim Jr. J.M.,CeeTox Inc.
Translational Stroke Research
In the present study, we used a comprehensive cellular toxicity (CeeTox) analysis panel to determine the toxicity profile for CNB-001 [4-((1E)-2-(5-(4-hydroxy-3-methoxystyryl-)-1-phenyl-1H-pyrazoyl-3-yl)vin yl)-2-methoxy-phenol)], which is a hybrid molecule created by combining cyclohexyl bisphenol A, a molecule with neurotrophic activity and curcumin, a spice with neuroprotective activity. CNB-001 is a lead development compound since we have recently shown that CNB-001 has significant preclinical efficacy both in vitro and in vivo. In this study, we compared the CeeTox profile of CNB-001 with two neuroprotective molecules that have been clinically tested for efficacy: the hydrophilic free radical spin trap agent NXY-059 and the hydrophobic free radical scavenger edaravone (Radicut). CeeTox analyses using a rat hepatoma cell line (H4IIE) resulted in estimated CTox value (i. e., sustained concentration expected to produce toxicity in a rat 14-day repeat dose study) of 42 μM for CNB-001 compared with >300 μM for both NXY-059 and Radicut. The CeeTox panel suggests that CNB-001 produces some adverse effects on cellular adenosine triphosphate content, membrane toxicity, glutathione content, and cell mass (or number), but only with high concentrations of the drug. After a 24-h exposure, the drug concentration that produced a half-maximal response (TC50) on the measures noted above ranges from 55 to 193 μM. Moreover, all CNB-001-induced changes in the markers were coincident with loss of cell number, prior to acute cell death as measured by membrane integrity, suggesting a cytostatic effect of CNB-001. NXY-059 and Radicut did not have acute toxic effects on H4IIE cells. We also found that CNB-001 resulted in an inhibition of ethoxyresorufin-odeethylase activity, indicating that the drug may affect cytochrome P4501A activity and that CNB-001 was metabolically unstable using a rat microsome assay system. For CNB-001, an estimated in vitro efficacy/toxicity ratio is 183-643-fold, suggesting that there is a significant therapeutic safety window for CNB-001 and that it should be further developed as a novel neuroprotective agent to treat stroke. © 2010 Springer Science+Business Media, LLC. Source
McKim Jr. J.M.,CeeTox Inc.
Combinatorial Chemistry and High Throughput Screening
One of the greatest challenges facing the pharmaceutical industry today is the failure of promising new drug candidates due to unanticipated adverse effects discovered during preclinical animal safety studies and clinical trials. Late stage attrition increases the time required to bring a new drug to market, inflates development costs, and represents a major source of inefficiency in the drug discovery/development process. It is generally recognized that early evaluation of new drug candidates is necessary to improve the process. Building in vitro data sets that can accurately predict adverse effects in vivo would allow compounds with high risk profiles to be deprioritized, while those that possess the requisite drug attributes and a lower risk profile are brought forward. In vitro cytotoxicity assays have been used for decades as a tool to understand hypotheses driven questions regarding mechanisms of toxicity. However, when used in a prospective manner, they have not been highly predictive of in vivo toxicity. Therefore, the issue may not be how to collect in vitro toxicity data, but rather how to translate in vitro toxicity data into meaningful in vivo effects. This review will focus on the development of an in vitro toxicity screening strategy that is based on a tiered approach to data collection combined with data interpretation. © 2010 Bentham Science Publishers Ltd. Source