Iloprost-Containing Liposomes for Aerosol Application in Pulmonary Arterial Hypertension: Formulation Aspects and Stability

Purpose The aim of this study was to kinetically and dynamically analyze in vitro cytotoxicity as an index of skin irritation by use of a three-dimensional cultured human skin model and to compare the in vitro assay data with data from living animals. Methods A cationic surfactant, cetylpyridinium chloride (CPC), was selected as a model irritant. Living skin equivalent-high (LSE-high) and hairless mice were used for the in vitro and in vivo tests, respectively. Skin irritation dermatodynamics was evaluated by calorimetric thiazoyl blue (MTT) conversion assay both for in vitro and in vivo tests, whereas dermatokinetics of CPC in LSE-high and mouse skin were evaluated using HPLC. Results The time course of cell viability in the skin after application of CPC to intact skin was distinctly different from that of stratum-corneum-stripped skin in both LSE-high and hairless mice. Biphasic behavior characterized by two first-order rates with an inflection time point was observed in intact skin, whereas cell viability monoexponentially decreased immediately after CPC application in stripped skin. The time courses of cell viability in the skin and dermatodynamics were closely related to that of dermatokinetics of CPC. Conclusion The present study demonstrates that the in vitro cytotoxic profile was similar to the in vivo cytotoxicity test and that dermatodynamics was related to dermatokinetics of CPC.     

Kinetic Analysis on the Skin Disposition of Cytotoxicity as an Index of Skin Irritation Produced by Cetylpyridinium Chloride: Comparison of In Vitro Data using a Three-Dimensional Cultured Human Skin Model with In Vivo Results in Hairless Mice

PURPOSE: The aim of this study was to kinetically and dynamically analyze in vitro cytotoxicity as an index of skin irritation by use of a three-dimensional cultured human skin model and to compare the in vitro assay data with data from living animals. METHODS: A cationic surfactant, cetylpyridinium chloride (CPC), was selected as a model irritant. Living skin equivalent-high (LSE-high) and hairless mice were used for the in vitro and in vivo tests, respectively. Skin irritation dermatodynamics was evaluated by calorimetric thiazoyl blue (MTT) conversion assay both for in vitro and in vivo tests, whereas dermatokinetics of CPC in LSE-high and mouse skin were evaluated using HPLC. RESULTS: The time course of cell viability in the skin after application of CPC to intact skin was distinctly different from that of stratum-corneum-stripped skin in both LSE-high and hairless mice. Biphasic behavior characterized by two first-order rates with an inflection time point was observed in intact skin, whereas cell viability monoexponentially decreased immediately after CPC application in stripped skin. The time courses of cell viability in the skin and dermatodynamics were closely related to that of dermatokinetics of CPC. CONCLUSION: The present study demonstrates that the in vitro cytotoxic profile was similar to the in vivo cytotoxicity test and that dermatodynamics was related to dermatokinetics of CPC.     

Non-occlusive topical exposure of human skin in vitro as model for cytotoxicity testing of irritant compounds

Testing of irritant compounds has traditionally been performed on animals and human volunteers. Animal testing should always be restricted and for skin irritancy mice and rabbits hold poor predictive value for irritant potential in humans. Irritant testing on human volunteers is restricted by the duration subjects can be exposed, and by the subjectivity of interpreting the visual signs of skin irritation. We propose an irritant testing system using viable human full thickness skin with the loss of cell viability in the exposed skin area as end point measurement. Skin was exposed to sodium dodecyl sulfate (SDS) at 20% concentration by non-occluded topical exposure to establish a positive control response and subsequent test compounds were statistically compared with the 20% SDS response. Cell viability and metabolism were measured with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The model presents correlation between increased concentration of SDS and decreased viability of cells in the exposed skin area (R²?=?0.76). We propose the model to be used for cytotoxicity testing of irritant compounds. With fully intact barrier function, the model comprises all cells present in the skin with quantifiable end point measurement.     

Acute Toxicity of Tetramethylbenzenes: Durene,Isodurene and Prehnitene

ABSTRACT

Oral LD₅₀ (rat), primary skin irritation (rabbit), cutaneous sensitization (guinea pig) and eye irritation (rabbit) studies were conducted on the three tetramethylbenzene isomers: durene, isodurene and prehnitene. The order of oral toxicity was isodurene > prehnitene > durene. Durene was not a skin irritant, while isodurene and prehnitene each produced a mild positive skin response (erythema). None of the tetramethylbenzenes were skin sensitizers or eye irritants. Durene, isodurene and prehnitene are only slightly toxic on an acute toxicologic basis and only pose an acute health hazard when injested in excessive quantities.     

Assessment of dermal irritation potential of MWCNT

There is an increasing concern regarding the potential toxicity of nanoparticles (NPs), but little literature is available on its skin toxicity and irritation potential. We investigated whether multi-walled carbon nanotubes (MWCNTs) affect skin irritation using HaCaT cell line, the human skin equivalent model (HSEM), and anin vivo model. We evaluated the cytotoxic effects of MWCNTs on HaCaT cells and the HSEM. To confirm in vitro results, we evaluated the irritation potentials of MWCNTs on rabbit skin. In MTT assay, MWCNTs cytotoxicity depended on the concentration of MWCNTs in HaCaT cells. The HSEM skin irriation experiments revealed that MWCNTs have no irritation potential. These HSEM data are consistent with Draize skin irritation test. MWCNTs did not induce the cutaneous irritation of rabbit skin. We suggest that MWCNTs do not induce any acute cutaneous irritation and the HSEM offers a useful alternative method for evaluating the toxicities of toxicants including NPs.     

Comparison of the endothelial toxicity induced by short-term amiodarone and diazepam exposure in a human umbilical vein endothelial cell line (EVC304)

Context: Venous irritation is the most common side effect of intravenous therapy. Although many in vitro models have been developed to evaluate intravenous drug irritation, these models are not widely accepted.

Objectives: The aim of this paper is to determine whether delayed or immediate cytotoxicity better reflects the in vivo venous irritation ranking.

Materials and methods: We compared the endothelial toxicity induced by high-concentrations of amiodarone and diazepam after short-term exposure (20?min) in a human umbilical vein endothelial cell line (EVC304) by using five in vitro models: lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD), glutathione (GSH), adenosine triphosphate (ATP), and MTT assays.

Results: In the 24-h MTT assay, the IC₅₀ of diazepam and amiodarone was 1.08 and 1.96?mM, respectively. In the 48-h MTT assay, the IC₅₀ of diazepam and amiodarone was 1.114 and 1.128?mM, respectively. In the intracellular LDH and G6PD assays, the EC₅₀ of diazepam was found to be 3.307 and 1.53?mM, while the values of amiodarone were 0.853 and 0.325?mM, respectively. In the intracellular ATP and GSH assays, the EC₅₀ of diazepam was 0.905 and 1.283?mM, while the values of amiodarone were 0.040 and 0.326?mM, respectively.

Conclusion: Both the results of intracellular macromolecule activities and micromolecule concentrations were similar to that observed in in vivo venous irritation studies. However, the delayed cytotoxicity rank from the MTT assay is inconsistent with the in vivo venous irritation rank, suggesting that initial toxicity, but not the delayed toxicity, is related to venous irritation.     

A new alternative method for testing skin irritation using a human skin model: A pilot study

BackgroundStudies assessing skin irritation to chemicals have traditionally used laboratory animals; however, such methods are questionable regarding their relevance for humans. New in vitro methods have been validated, such as the reconstructed human epidermis (RHE) model (Episkin®, Epiderm®). The comparison (accuracy) with in vivo results such as the 4-h human patch test (HPT) is 76% at best (Epiderm®). There is a need to develop an in vitro method that better simulates the anatomo-pathological changes encountered in vivo.ObjectivesTo develop an in vitro method to determine skin irritation using human viable skin through histopathology, and compare the results of 4 tested substances to the main in vitro methods and in vivo animal method (Draize test).MethodologyHuman skin removed during surgery was dermatomed and mounted on an in vitro flow-through diffusion cell system. Ten chemicals with known non-irritant (heptylbutyrate, hexylsalicylate, butylmethacrylate, isoproturon, bentazon, DEHP and methylisothiazolinone (MI)) and irritant properties (folpet, 1-bromohexane and methylchloroisothiazolinone (MCI/MI)), a negative control (sodiumchloride) and a positive control (sodiumlaurylsulphate) were applied. The skin was exposed at least for 4 h. Histopathology was performed to investigate irritation signs (spongiosis, necrosis, vacuolization).ResultsWe obtained 100% accuracy with the HPT model; 75% with the RHE models and 50% with the Draize test for 4 tested substances. The coefficients of variation (CV) between our three test batches were <0.1, showing good reproducibility. Furthermore, we reported objectively histopathological irritation signs (irritation scale): strong (folpet), significant (1-bromohexane), slight (MCI/MI at 750/250 ppm) and none (isoproturon, bentazon, DEHP and MI).ConclusionsThis new in vitro test method presented effective results for the tested chemicals. It should be further validated using a greater number of substances; and tested in different laboratories in order to suitably evaluate reproducibility.     

Development of the short time exposure (STE) test: an in vitro eye irritation test using SIRC cells.

Using SIRC (rabbit corneal cell line) cells, we developed an alternative eye irritation test: the short time exposure (STE) test. This STE test is a cytotoxicity test using physiological saline or mineral oil as the test solvent. Evaluation exposure time is short (5 min), which is similar to actual exposure situations, and uses the cell viability (CV) at a constant concentration as the endpoint for irritation potential. First, in order to confirm the usefulness of this STE test in assessing eye irritation potential of chemicals, 51 raw materials were tested and the correlation between CV in the STE test and the eye irritation score in the Draize test was examined. For the undiluted raw materials tested in the Draize test, the 5% test concentration in the STE test gave irritation classes that correlated well with the irritation classes from the Draize test (accuracy: 89.6%). For those materials tested as a 10% solution in the Draize test, STE irritation classes with 0.05% test concentration corresponded well with the Draize irritation classes (accuracy: 80.0%). Next, using the cell viabilities at these two concentrations, the STE prediction model (PM) was developed. A score of 1 or 2 was given for the results from each tested concentration in the STE test and Draize test. The scores from each test were then summed to yield a 3-level (Rank 1: minimally irritant, Rank 2: moderate irritant, Rank 3: severe irritant) eye irritation potential classification. Rank classification in the STE test showed a good correlation mostly to that in the Draize test (irritation class correspondence rate: 70.2%, but after exclusion of data of alcoholic materials, the rate was 91.7%). In most cytotoxicity test, the cytotoxicity of acids and amines is generally underestimated due the use of medium as the solvent. This is the result of the buffering capacity of the media. On the other hand, the STE test could predict the eye irritation potential by evaluating the chemical with a 5% test concentration. Eleven water insoluble materials such as toluene, octanol, and hexanol could be evaluated by using mineral oil as test solvent in the STE test. The STE test demonstrated itself to be simple, promising, have great potential, be of value, and to be an easily standardized alternative eye irritation test.     

狗皮膏安全性评价研究

目的 对狗皮膏的皮肤用药安全性进行评价研究。方法 取不同厂家样品10批分别进行家兔急性皮肤刺激性试验和豚鼠皮肤过敏性试验,同时采用原子吸收分光光度法测定给药后家兔血铅浓度的变化。结果 10批样品中有7批出现皮肤刺激反应,除A厂家1批为中度刺激性,其余为轻度刺激性;10批样品均未见皮肤过敏反应;狗皮膏连续给药7 d后,给药组的血铅浓度与对照组相比差异有统计学意义（P＜0.01）,连续给药14 d后的血铅浓度与连续给药7 d相比差异有统计学意义（P＜0.05）。结论 狗皮膏引起皮肤刺激反应的风险较大,且不同厂家间、厂内批次间存在差异;久贴狗皮膏可引起血铅升高,建议改善制剂以减轻不良反应。     

An in vitro model for detecting skin irritants: methyl green-pyronine staining of human skin explant cultures.

We evaluated the potential of human organotypic skin explant cultures (hOSECs) for screening skin irritants. Test chemicals were applied to the epidermis of the skin explants which were incubated for 4, 24 or 48 h in tissue culture medium. A decrease in epidermal RNA staining, visualised in frozen sections using a modified methyl-green pyronine (MGP) staining procedure, was used as a marker of irritancy. A decrease in epidermal RNA after a 4-, 24- or 48-h exposure to a certain concentration of a test chemical equated to a MGP score of 3, 2 or 1, respectively. The MGP score was 0 if there was no keratinocyte cytotoxicity after a 48-h exposure. A minimum of three donors were used per chemical and the average MGP score was used to classify the chemical as irritant or not. Chemicals with an average MGP score > or =1.5 were classified as irritants (R38), at that concentration. Chemicals with a MGP score <1.5 were not classified (NC), at that concentration. The results obtained using human skin in vitro were compared with published data obtained using cultured porcine skin, the cutaneous Draize test (from this point referred to as the "rabbit skin irritation test") and volunteer studies. There was an excellent correlation between the classification of a chemical, as R38 or NC, based on hOSEC and results of volunteer studies. The hOSEC model predicted perfectly the irritation hazard of the 22 chemicals for which volunteer data were available. The porcine OSEC correctly predicted the classification of 21 of 22 (95%) chemicals and the rabbit skin irritation test correctly predicted the classification of 14 of 15 chemicals (93%) for which data were available. In conclusion, MGP staining of human skin explant cultures can be used to predicted human skin irritancy in vivo. In addition, the data validate the use of porcine skin as an alternative to human skin for screening for dermal irritants in vitro.     

吲哚美辛乳剂对皮肤刺激性和过敏性研究

目的考察吲哚美辛乳剂的皮肤刺激性和皮肤过敏性,为临床安全用药提供依据。方法采用新西兰白兔进行皮肤刺激性实验,分为完整皮肤组和破损皮肤组,每组8只。采用同体左、右侧自身对比法,左侧给予吲哚美辛乳剂0.5g,右侧给予等量空白乳剂,连续给药14d。实验期间观察皮肤刺激反应,每组6只于末次给药后72h处死,取皮肤做组织病理检查,剩余2只于末次给药后14d取皮肤做病理检查。采用豚鼠进行皮肤过敏实验,于第0、7、14天给予吲哚美辛0.5g局部诱导,第28天在未给药豚鼠的肋腹部皮肤给予吲哚美辛0.4g以局部激发。结果吲哚美辛乳剂对兔正常皮肤和破损皮肤均有轻微刺激性,但停药后可恢复,对豚鼠皮肤无过敏反应。结论吲哚美辛乳剂在临床上不宜长期使用,需重点观察皮肤刺激性。     

Evaluation of the antileishmanial potency,toxicity and phytochemical constituents of methanol bark extract of Sterculia villosa

Context: Visceral leishmaniasis is a protozoan disease caused by Leishmania donovani parasite. The genus Sterculia (Malvaceae) possesses ethnobotanical potential against this protozoan infection.

Objective: Determining the potential role of methanol bark extracts from Sterculia villosa Roxb (SVE) and its phytoconstituents against Leishmania donovani promastigotes.

Materials and methods: SVE was analysed by TLC, UV–Vis, IR spectroscopy and biochemical assays. Antileishmanial potential of SVE (0.5–130?μg/mL for 72?h) was characterized by MTT assay. Fluorescent microscopy was performed to validate the IC₅₀ dose. To determine the effect of SVE on promastigotes, reactive oxygen species (ROS) and superoxide generation, lipid peroxidation and DNA fragmentation assays were performed. Molecular aggregation of compounds was determined by atomic force microscopy (AFM). Extent of cytotoxicity of SVE at IC₅₀ dose was determined against RAW 264.7 macrophages, peritoneal macrophages and murine RBCs. In vivo cytotoxicity of SVE was evaluated in BALB/c mice.

Result: SVE exhibited reverse dose dependent antileishmanial activity when 130–0?μg/mL doses were tested against promastigotes. The IC₅₀ and IC₇₀ values were found to be 17.5 and 10?μg/mL, respectively. SVE at IC₅₀ dose demonstrated elevated level of ROS, superoxide, lipid peroxidation and DNA fragmentation against promastigotes with no cytotoxicity. AFM analysis suggested increasing size of molecular aggregation (31.3?nm Discussion and conclusions: The study elucidates the antileishmanial potential of SVE against Leishmania donovani promastigotes by exerting oxidative stress and DNA damage. In sum, SVE can be explored as an immunotherapeutic candidate against leishmaniasis and other infectious diseases.     

光甘草定醇质体与立方液晶纳米粒皮肤滞留量比较及抗豚鼠皮肤光老化作用观察

目的 制备光甘草定醇质体与立方液晶纳米粒,通过测定2种纳米制剂在离体豚鼠皮肤中的滞留量优选出适合光老化经皮给药的制剂。建立光老化模型,通过观察优选制剂对豚鼠光老化模型的治疗效果来评价药物的疗效。方法 采用注入法制备光甘草定醇质体,高压均质法制备光甘草定立方液晶纳米粒,利用Franz扩散装置考察光甘草定醇质体、立方液晶纳米粒凝胶离体鼠皮中的滞留量,优选出光甘草定经皮给药治疗光老化的纳米制剂。紫外线照射背部剃毛豚鼠建立皮肤光老化模型。雌性豚鼠随机分为模型组、基质（给予空白凝胶0.5 g/只）组、维甲酸（阳性对照,0.5 g/只）组和甘草定立方液晶纳米粒凝胶高、低剂量（0.50、0.25 g/只）组,治疗2周后,通过肉眼观察、HE染色、Masson染色等评价其治疗效果,用水份测定仪观察其对豚鼠皮肤含水量的影响。结果 2种纳米制剂凝胶的鼠皮滞留量最高者为光甘草定立方液晶纳米粒凝胶。豚鼠皮肤光老化模型建立成功,HE染色、Masson染色等结果表明光甘草定立方液晶纳米粒对光老化有明显的治疗效果,使光老化皮肤的含水量显著升高（P<0.05）。结论 光甘草定立方液晶纳米粒在离体鼠皮中的滞留较高,对豚鼠皮肤光老化模型治疗效果显著,为光甘草定的临床应用提供了新的方法与思路。     

鸡胚绒毛膜尿囊膜血管试验用于评价化妆品配方眼刺激性质量标准的建立与评价

目的 建立鸡胚绒毛膜尿囊膜血管试验用于评价化妆品配方眼刺激性的标准。方法 通过对鸡胚绒毛膜尿囊膜血管试验原有判定方法的改进,建立针对化妆品配方眼刺激性评价的质量标准,以此对10种不同类型共20批次的化妆品配方进行眼刺激性评价,并将结果与家兔法相比较,验证质量标准的可行性。结果 20批次的化妆品配方鸡胚绒毛膜尿囊膜血管试验结果与家兔法相比一致率为85%（17/20）。结论 所建立的标准可用于化妆品配方眼刺激性评价。     

In vivo and in vitro toxicological evaluations of aqueous extract from Cecropia pachystachya leaves

ABSTRACT

Cecropia pachystachya

leaves are popularly used to treat asthma and diabetes. Despite the widespread consumption of this plant, there are few scientific studies regarding its toxicological potential. In order to conduct a thorough study concerning the potential adverse effects, the aim of this study was to assess acute and subacute toxicity tests of crude aqueous extract from C. pachystachya leaves (CAE-Cp) using in vivomodel, as well as in vitro cytotoxicity, genotoxicity and antioxidant activity. In addition, genotoxicity, and cytotoxicity of chlorogenic acid (CGA) and cytotoxicity of isoorientin (ISOO) were also evaluated. The antioxidant activity was verified by DPPH, cytotoxicity using sulforhodamine B (SRB) assay and genotoxicity by comet assay on V79 cells. The phytochemical analysis of CAE-Cp detected flavonoids and tannins, CGA and ISOO as the major compounds utilizing HPLC. The total flavonoid content (6.52 mg/g EQ) and antioxidant activity (EC₅₀ = 62.15 µg/ml) of CAE-Cp were determined. In vitro evaluations with CAE-Cp showed genotoxic effects at 0.31 to 2.5 mg/ml and an expressive cytotoxicity on HT-29 (IC₅₀ = 4.43 µg/ml) cells. CGA was genotoxic against V79 cells at 0.07 mg/ml and cytotoxic against to HT-29 (IC₅₀ = 71.70 µg/ml), OVCAR-3 (IC₅₀ = 80.07 µg/ml), MCF-7 (IC₅₀ = 45.58 µg/ml) and, NCI-H460 (IC₅₀ = 71.89 µg/ml) cancer cell lines. Wistar rats treated with a single dose (2,000 mg/kg) CAE-Cp decreased hemoglobin levels after 14 days, although no significant toxicity was observed in animals after 28 days. In view of the in vitro cytotoxicity and genotoxicity detected, further studies are necessary to establish the safe use of CAE-Cp.     

Wound healing activity of Pluchea indica leaf extract in oral mucosal cell line and oral spray formulation containing nanoparticles of the extract

Context: Pluchea indica (L.) Less (Asteraceae) is an herb used as a traditional medicine for wound healing. The chemical compounds found in Pluchea indica leaves are phenolic acids, flavonoids, anthocyanins and carotenoids.

Objective: This study investigates the effect of Pluchea indica leaf ethanol extract and its nanoparticles (NPs) on cytotoxicity, cell survival and migration of human oral squamous carcinoma cell line.

Materials and methods: Cell viability was measured using MTT assay to assess the effect of Pluchea indica leaf extract and NPs (1–500?μg/mL) on cytotoxicity and cell survival. The effect of Pluchea indica leaf extract and NPs on cell migration was determined by scratch assay. The % relative migration was calculated after 24, 48 and 72?h of treatment.

Results: The sizes of Pluchea indica leaf extract NPs were in a range of nanometers. NPs possessed negative charge with the polydispersity index (PDI) smaller than 0.3. After the treatment for 24, 48 and 72?h, Pluchea indica leaf extract had IC₅₀ value of 443.2, 350.9 and 580.5?μg/mL, respectively, whereas the IC₅₀ value of NPs after the treatment for 24, 48 and 72?h were 177.4, 149.2 and 185.1?μg/mL, respectively. The % relative migration of cells was significantly increased when the cells were treated with 62.5 and 125?μg/mL of the extract and 62.5?μg/mL of NPs.

Discussion and Conclusions: NPs increased cytotoxicity of the Pluchea indica leaf extract, increased the migration of cells at low concentration and increased colloidal stability of the extract in an oral spray formulation.     

The SDA Alternatives Program Phase III: Comparison of in Vitro Data with Animal Eye Irritation Data on Solvents,Surfactants, Oxidizing Agents,and Prototype Cleaning Products

Abstract

Nine in vitro candidate tests for estimating eye irritation potential were evaluated as potential replacements for the Draize test. The tests examined were a cell protein assay, the chorioallantoic membrane vascularization assay, a cell protein assay, a fibroblast cytotoxicity assay, the Living Dermal Model and Living Skin Equivalent, two neutral red assays, an SIRC cytotoxicity assay, and a Tetrahymena thermophila motility assay. The results from these in vitro tests were compared to results from a modified Draize test with 22 test materials. The test materials were selected to represent various classes of cleaning products and ingredients. Ingredients were tested at concentrations representative of concentrations typically found in cleaning products. The correlation coefficients with all test materials considered ranged from 0.58 to 0.91. When only nonalkaline materials are considered, the correlation coefficients of all 10 tests were not significantly different from one another, ranging from 0.8 to 0.9. The assays least affected by the alkalinity of the test substances were the corneal epithelial plasminogen activator assay, the chorioallantoic membrane vascular assay, and the Tetrahymena motility assay. Further, six of the 10 tests were able to identify the five nonirritants in the study, although the relative irritation potentials of the irritants were not accurately predicted by any of the tests. Results from a low-volume eye irritation test (LVET) were also compared to results from a modified Draize test with the same 22 test materials. The LVET had a high correlation with the modified Draize test and will be useful for future comparison with other alternative eye irritation tests. Based on these data, a number of alternative tests developed to replace the Draize eye irritation test included in this phase of research are useful for screening the eye irritation potential of nonalkaline cleaning products, although some tests are better for identifying the eye irritation potential of test materials with alkaline or oxidation potential. Although the ability of the eye to recover from damage was not measured by any test, the tests show promise for the use of determining eye irritation potential.     

Screening for potential hazard effects from four nitramines on human eye and skin

Amines have potential to be used in CO₂ capture and storage (CCS) technology, but as they can be released into the environment and be degraded into more toxic compounds, such as nitrosamines and nitramines, there have been concerns about their negative impact on human health. We investigated the potential toxic effects from acute exposure to dimethylnitramine (DMA–NO₂), methylnitramine (MA-NO₂), ethanolnitramine (MEA-NO₂) and 2-methyl-2-(nitroamino)-1-propanol (AMP-NO₂). The eye irritation, and skin sensitization, irritation and corrosion potential of these substances have been evaluated in vitro using the Bovine Corneal Opacity and Permeability (BCOP) assay, VITOSENS® assay, Reconstructed Human Epidermis (RHE) skin irritation test and Corrositex Skin corrosion test, respectively. Exposure to DMA–NO₂ induced a mild eye irritation response, while MA-NO₂, MEA-NO₂ and AMP-NO₂ were shown to be very severe eye irritants. MA-NO₂ and MEA-NO₂ were tested for skin sensitization and found to be non-sensitizers to the skin. In addition, none of the four test substances was irritant or corrosive to the skin.     

Toxicological studies on sophorolipid derivatives. (I). Acute toxicity, eye irritation, primary skin irritation, skin sensitization, phototoxicity, photosensitization, mutagenicity of polyoxypropylene (12) [(2'-0-beta-D-glucopyranosyl-beta-D-glucopyranosyl)oxy-] fatty acid ester-

Acute toxicity, eye irritation, primary skin irritation, skin sensitization, phototoxicity, photosensitization and mutagenicity of sophorolipid derivatives were studied in rats, mice, rabbits, guinea pigs and Salmonella typhimurium strains. The acute oral toxicity of sophorolipid (SL) which Torulopsis bombicola produces, and its derivatives (PSL, Ethyl-SL and Oleyl-SL) were shown to be very low. The LD50 values of PSL ranged from 10 g/kg to 16 g/kg on oral administration in rats and mice, and from 5.8 g/kg to 6.6 g/kg on subcutaneous administration in mice. The oral LD50 values of Ethyl-SL and Oleyl-SL were estimated to be greater than 15 g/kg and that of SL was 12.5 g/kg. In eye irritation study, PSL failed to produce any reactions at 50% concentration even when the rabbit eye was not subsequently washed. SL, Ethyl-SL, Oleyl-SL and Tween 20 were "no irritant" or "slight irritant" to the rabbit eye at 20% concentration. PSL showed no irritancy to both the intact and abraded guinea pig skin at 50% concentration. And in other examinations, it was also indicated that PSL had no potentials of skin sensitization, phototoxicity and photosensitization in guinea pigs and had no potentials of mutagenicity in Salmonella typhimurium TA98 and TA100.     

A microelectric cell sensing technique for in vitro assessment of ocular irritation

The animal-based Draize test remains the gold standard for assessment of ocular irritation. However, subjective scoring methods, species differences, and animal welfare concerns have spurred development of alternative test methods. In this study, a novel in vitro method for assessing ocular irritancy was developed using a microelectric cell sensing technology, real-time cell analysis (RTCA). The cytotoxicity of sixteen compounds was assessed in two cell lines: ARPE-19 (human retina) and SIRC (rabbit cornea). In vitro inhibitory (IC₅₀ and AUC₅₀) values were determined at 6, 12, 24, 48, 72, and 96 h exposure, with a subset of values confirmed with MTT testing. The values displayed comparable predictivity of in vivo ocular irritation on the basis of a linear regression between the calculated values and each compounds' corresponding Draize-determined modified maximum average score (MMAS), but the ARPE-19 derived values were more strongly correlated than those from SIRC cells. Hence, IC₅₀ values derived from ARPE-19 cells were used to predict the UN GHS/EU CLP classification of each test compound. The method was determined to have sensitivity of 90%, specificity of 50%, and overall concordance of 75%. Thus, RTCA testing may be best incorporated into a top-down tiered testing strategy for identification of ocular irritants in vitro.