The Future of Uncertainty Factors With In Vitro Studies Using Human Cells.

New approach methodologies (NAMs), including in vitro toxicology methods such as human cells from simple cell cultures to 3D and organ-on-a-chip models of human lung, intestine, liver, and other organs, are challenging the traditional "norm" of current regulatory risk assessments. Uncertainty Factors continue to be used by regulatory agencies to account for perceived deficits in toxicology data. With the expanded use of human cell NAMs, the question "Are uncertainty factors needed when human cells are used?" becomes a key topic in the development of 21st-century regulatory risk assessment. M.D., PhD, the coauthor of an article detailing uncertainty factors within the U.S. EPA, and L.E., PhD., Executive Vice President, Science, Emulate, who is involved in developing organ-on-a-chip models, debated the topic. One important outcome of the debate was that in the case of in vitro human cells on a chip, the interspecies (animal to human) uncertainty factor of 10 could be eliminated. However, in the case of the intraspecies (average human to sensitive human), the uncertainty factor of 10, additional toxicokinetic and/or toxicodynamic data or related information will be needed to reduce much less eliminate this factor. In the case of other currently used uncertainty factors, such as lowest observable adverse effect level to no-observed adverse effect level extrapolation, missing important toxicity studies, and acute/subchronic to chronic exposure extrapolation, additional data might be needed even when using in vitro human cells. Collaboration between traditional risk assessors with decades of experience with in vivo data and risk assessors working with modern technologies like organ chips is needed to find a way forward.

Water-soluble and organic extracts of airborne particulate matter induce micronuclei in human lung epithelial A549 cells.

The in vitro genotoxic effects of organic and water-soluble fractions of airborne particulate matter (PM10) with the cytokinesis blocked micronucleus (MN) test in human alveolar carcinoma cells A549 were investigated. Samples were collected in three different sites of São Paulo State, Brazil, and fifteen soluble metals and the sixteen EPÁs priority polycyclic aromatic hydrocarbons (PAH) were chemically determined. PAHs prevailing were fluoranthene and benzo(ghi)perylene. In the water-soluble extracts, highest concentration of metals was found for zinc, iron, and copper in all places of collection. Although PM10 concentration in all samples was in the range of 33.5-110.1µg/m3, lower than 120µg/m3 (limit established by São Paulo State's legislation for PM10 in 24h), MN results showed that of the 24 samples analyzed, five organic and seven water-soluble extracts presented a significant increase in MN frequency. The frequency of MN correlates with the total PAH concentration of the three sites investigated, and the concentration of PM10 is correlated with the biological effect in two of them. For the water-soluble fraction, all the sites presented a relation between the PM10 concentration and the MN frequency. Again, the genotoxic response showed a correlation with the total concentration of water-soluble metals in two of the three sites. Our results confirm the importance of the soluble fraction of PM10 to the genotoxic effect of airborne PM even at low concentration of water-soluble compounds. Thus, together with chemical analysis, the implementation of the MN protocol for both organic and water-soluble fraction biological monitoring could be used as a strategy in a routine air-quality monitoring program, complementing other usual analyses for air pollution control and protection of populations.

Evaluating the mutagenicity of the water-soluble fraction of air particulate matter: A comparison of two extraction strategies.

Many studies have focused on assessing the genotoxic potential of the organic fraction of airborne particulate matter. However, the determination of water-soluble compounds, and the evaluation of the toxic effects of these elements can also provide valuable information for the development of novel strategies to control atmospheric air pollution. To determine an appropriate extraction method for assessing the mutagenicity of the water-soluble fraction of PM, we performed microwave assisted (MW) and ultrasonic bath (US) extractions, using water as solvent, in eight different air samples (TSP and PM10). Mutagenicity and extraction performances were evaluated using the Salmonella/microsome assay with strains TA98 and TA100, followed by chemical determination of water-soluble metals. Additionally, we evaluated the chemical and biological stability of the extracts testing their mutagenic potential and chemically determining elements present in the samples along several periods after extraction. Reference material SRM 1648a was used. The comparison of MW and US extractions did not show differences on the metals concentrations, however positive mutagenic responses were detected with TA98 strain in all samples extracted using the MW method, but not with the US bath extraction. The recovery, using reference material was better in samples extracted with MW. We concluded that the MW extraction is more efficient to assess the mutagenic activity of the soluble fraction of airborne PM. We also observed that the extract freezing and storage over 60 days has a significant effect on the mutagenic and analytical results on PM samples, and should be avoided.

The oxidation of p-phenylenediamine, an ingredient used for permanent hair dyeing purposes, leads to the formation of hydroxyl radicals: Oxidative stress and DNA damage in human immortalized keratinocytes.

The hair-dyeing ingredient, p-phenylenediamine (PPD), was previously reported to be mutagenic, possibly by inducing oxidative stress. However, the exact mechanism of PPD in inducing oxidative stress upon skin exposure during hair-dyeing in human keratinocytes remains unknown. The aim of our studies was therefore to investigate the toxicity of PPD and its by-products in human immortalized keratinocytes (HaCaT) after auto-oxidation and after reaction with hydrogen peroxide (H2O2). We found that the PPD half maximal effective cytotoxic concentration (EC50) to HaCaT is 39.37 and 35.63 µg/mL after 24 and 48 h, respectively, without addition of H2O2 to induce oxidation. When PPD (10 or 100 µg/mL) is combined with 10.5 µg/mL of H2O2, intracellular ROS production by HaCaT after 1 h was significantly increased and enhanced levels of DNA damage were observed after 4 h of exposure. After 24 h incubations, 20 µg/mL of PPD increased the level of DNA oxidation in HaCaT. Also, we found that the in vitro reaction between PPD and H2O2, even below the maximum allowance by cosmetic industries, released hydroxyl radicals which can damage DNA. Taken together, we conclude that PPD alone and when combined with H2O2 increases the formation of reactive oxygen species in human keratinocytes, leading to oxidative stress and subsequent DNA damage. These alterations suggest that the mechanism by which PPD exposure, alone or combined with H2O2, damages keratinocytes by the formation of the high reactive HO∙ radicals.

MMP-9 expression increases according to the grade of squamous intraepithelial lesion in cervical smears.

Studies about cervical carcinogenesis have demonstrated the increased expression of matrix-metalloproteinase (MMP) according to the grade of cervical intraepithelial lesions. Considering the importance of innovative techniques to introduce noninvasive and rapid diagnoses for patients, this study aimed to perform MMP-9 immunocytochemistry in cervical smears according to the cytopathological diagnoses, in order to monitor MMP activity in cervical smears. This cross-sectional study investigated the expression of MMP-9 in normal cervical smears, inflammatory cervical smears, squamous intraepithelial lesions, and cervical carcinoma. Cervical smears from 630 women were collected for cytopathological diagnoses and immunocytochemistry. Women with squamous intraepithelial lesions showed an increase in MMP-9 expression, with moderate to intense staining occurring with increasing cervical lesion grade. The prevalence of moderate to intense MMP-9 staining was 9% in normal cervical smears, 12% in cervical inflammation, 24% in low-grade squamous intraepithelial lesion (LSIL), 92% in high-grade squamous intraepithelial lesions (HSIL) and 100% in cervical carcinoma cases. In the specific case of LSIL, we found that association with MMP-9 is more evident when there is the simultaneous presence of an infectious agent. Thus, the expression of MMP-9 in cervical smears increases according to the grade of cervical lesion and LSIL in the presence of infectious agents showed higher MMP-9 expression than women with LSIL without infectious agents.

Hydrolysis influence on phytochemical composition, antioxidant activity, plasma concentration, and tissue distribution of hydroethanolic Ilex paraguariensis extract components.

The infusion of aerial parts of Ilex paraguariensis is widely consumed. Its antioxidant activity suggests an important role of this plant in the treatment/prevention of oxidative stress related diseases. Plant extract active compounds are frequently found in esterified form that may be poorly absorbed. Hydrolysis of the extract is a possible approach to increase its bioavailability. The aim of this study was to perform a phytochemical analysis and evaluate in rats the plasma concentration and tissue distribution of antioxidant compounds in the hydroethanolic extract of Ilex paraguariensis, before and after enzymatic hydrolysis. Both extracts presented high antioxidant activity and phenolic content. Rats given single or repeated doses of the hydrolyzed extract showed increased plasma antioxidant activity and higher plasma levels of caffeic acid. However, no changes of endogenous antioxidants were observed. In conclusion, hydrolysis of the extract of Ilex paraguariensis is a strategy to improve its bioavailability and in vivo antioxidant activity.

Chlorogenic acid UVA­UVB photostability.

Chlorogenic acid is a natural potent antioxidant. It can be used in cosmetics formulations, but for this purpose its photochemical stability should be determined to ensure that the compound will not be degraded after UV radiation exposure. To evaluate this possibility, the concentration of a chlorogenic acid solution was determined by HPLC before and after UVA and UVB irradiation.The results indicate that chlorogenic acid is not degraded under UVA or UVB irradiation.

Atividades antiúlcera e antioxidante do extrato de folhas de Syzygium jambos (L) Alston (Myrtaceae) / Antiulcerogenic and antioxidant activities of leaf extract of Syzygium jambos (L) Alston (Myrtaceae)

Syzygium jambos (L.) Alston, Myrtaceae, é empregado na medicina popular como digestivo e antiinflamatório. A triagem fitoquímica da droga pulverizada (folhas) indicou a presença de flavonóides, taninos e óleo volátil. O extrato hidroetanólico a 70 por cento das folhas de S. jambos foi preparado por percolação e liofilizado. O conteúdo de taninos das folhas e do extrato foi calculado, respectivamente, em 21,9 por cento e 43,3 por cento. O teor de flavonóides foi de 0,6 por cento (folhas) e 1,2 por cento (extrato). A administração oral prévia do extrato (400 mg/kg) a ratos Wistar reduziu significativamente as lesões gástricas induzidas por etanol acidificado. No modelo de úlcera subcrônica, com indução de lesão gástrica utilizando ácido acético a 30 por cento, o tratamento com o extrato (400 mg/kg) não apresentou resultado significativo. A atividade antioxidante do extrato foi avaliada através dos modelos de lipoperoxidação e de medida de capacidade seqüestrante de radicais DPPH. Os valores obtidos de Q1/2 (MDA) e CE50 (DPPH) foram, respectivamente, 0,17 μg/mL e 5,68 μg/mL.

Syzygium jambos (L.) Alston, Myrtaceae, is commonly employed in folk medicine as digestive and anti-inflammatory. Phytochemical screening of the powdered dried leaves indicates the presence of flavonoids, tannins and essential oil. Hydroethanol extracts (70 percent) were prepared by percolation and freeze-drying. The tannin content of dried leaves and extract was, respectively, 21.9 percent and 43.3 percent. The flavonoid content was 0.6 percent (dried leaves) and 1.2 percent (extract). Previous oral administration of S. jambos leaves extract (400 mg/kg) to rats reduced significantly gastric injury induced by HCl/ethanol. At the subcronic ulcer model by induction with 30 percent acetic acid the results were not significant. In vitro antioxidant activity of S. jambos extract was evaluated by malondialdehyde (MDA) and DPPH free radical method. The Q1/2 for MDA assay was 0.17 μg/mL and the EC50 for DPPH assay was 5.68 μg/mL.

Optimization of Pothomorphe umbellata (L.) Miquel topical formulations using experimental design.

Pothomorphe umbellata is a native plant widely employed in the Brazilian popular medicine. This plant has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced skin damage and photoaging. The aim of this work was to optimize the appearance, the centrifuge stability and the permeation of emulsions containing P. umbellata (0.1% 4-nerolidylchatecol). Experimental design was used to study ternary mixtures models with constraints and graphical representation by phase diagrams. The constraints reduce the possible experimental domain, and for this reason, this methodology offers the maximum information while requiring the minimum investment. The results showed that the appearance follows a linear model, and that the aqueous phase was the principal factor affecting the appearance; the centrifuge stability parameter followed a mathematic quadratic model and the interactions between factors produced the most stable emulsions; skin permeation was improved by the oil phase, following a linear model generated by data analysis. We propose as optimized P. umbellata formulation: 68.4% aqueous phase, 26.6% oil phase and 5.0% of self-emulsifying phase. This formulation displayed an acceptable compromise between factors and responses investigated.

Ascorbic acid levels of aqueous humor of dogs after experimental phacoemulsification.

Phacoemulsification has been successfully employed in humans and animals for lens extraction. This ultrasonic extracapsular surgical technique induces hydroxyl radical formation in the anterior chamber, which accumulates despite irrigation and aspiration. In this paper we determined the total antioxidant status of aqueous humor after phacoemulsification by measuring aqueous humor ascorbic acid levels. Mixed-breed dogs (n = 11; weighing about 10 kg) with normal eyes as determined by slit-lamp biomicroscopy, applanation tonometry, and indirect ophthalmoscopy had phacoemulsification performed in one eye with the other eye used as a control. Samples of aqueous humor were obtained by anterior chamber paracentesis before surgery and at days 1, 2, 3, 7, and 15 after surgery. Total aqueous humor antioxidant status was inferred from the capacity of aqueous humor to inhibit free radical generation by 2,2-azobis (2-amidopropane) chlorine. Ascorbic acid concentrations were measured by high-pressure liquid chromatography with UV detection. Protein content was determined with the biuret reagent. Statistical analysis was performed by anova followed by the paired t-test. Total antioxidant capacity was reduced from 48 to 27 min during the first 24 h with a gradual increase thereafter, remaining statistically lower than the control eye until 7 days postoperatively. Reduced levels of ascorbic acid followed this reduction in antioxidant capacity (from 211 to 99 microm after 24 h), remaining lower than the control eye until 15 days postoperatively. Protein concentration in aqueous humor increased from 0.62 mg/mL to 30.8 mg/mL 24 h after surgery, remaining statistically lower than the control eye until 15 days postoperatively. Paracentesis alone did not significantly alter the parameters measured. These results indicate that after phacoemulsification, the aqueous humor ascorbic acid levels and antioxidant defenses in aqueous humor are reduced, indirectly corroborating free radical production in the anterior chamber as a result of phacoemulsification. The inflammatory process consequent to the surgical procedure demonstrated by increased protein content in aqueous humor can also contribute to free radical production and ascorbic acid consumption.

In vitro and in vivo inhibition of skin matrix metalloproteinases by Pothomorphe umbellata root extract.

Exposure to UV radiation up-regulates the synthesis of matrix metalloproteinases (MMPs), a group of matrix-degrading enzymes. MMPs are regarded as promising therapeutic targets and the development of effective inhibitors is an important research focus. The plant Pothomorphe umbellata has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced chronic skin damage. The aim of the present study was to determine the effect of P. umbellata ethanolic root extract on MMP-2 and MMP-9. The in vitro inhibition of MMP-2 and MMP-9 was measured by gelatin zymography in the presence of different concentrations of P. umbellata extract, as well as in the presence of its isolated active principle 4-nerolidylcatechol (4-NC). The inhibitory effect of the P. umbellata extract was stronger than that of 4-NC. Gelatin zymography and histological analysis revealed that P. umbellata was able to inhibit constitutive MMP-9 activity in vivo in mice sacrificed 2 h after UVB irradiation. The intensity of the MMP-2 band was unchanged. Our data contribute to the elucidation of the mechanism of prevention of photoaging by P. umbellata and may provide a rational basis for the use of this plant in prophylaxis against and treatment of skin cancer.

Chemical stability and SPF determination of Pothomorphe umbellata extract gel and photostability of 4-nerolidylcathecol.

Due to its antioxidant and photoprotective properties, Pothomorphe umbellata is a promising candidate for use in cosmetic and pharmaceutical formulations. These properties arise from the presence of 4-nerolidylcathecol (4-NC), a polyphenolic compound isolated from P. umbellata roots. This study investigates its photostability properties, as well as the chemical and the in vitro sun protection factor (SPF) of P. umbellata root extract in a gel formulation. A high performance liquid chromatography method was used to evaluate the chemical stability using 4-NC as marker at 5, 25 and 45 degrees C for 103 days. The photostability and the sun protection factor were analyzed by ultraviolet (UV) spectophotometry using samples irradiated with UVB lamp. No significant difference of the 4-NC concentration was found in formulations stored at 5 and 25 degrees C. All samples stored at 45 degrees C, however, showed degradation of gel structure. After 2h of UVB exposure, there was no change in the absorption profile of 4-NC. The sun protection factor of P. umbellata root extract gel to final concentration of 0.1% 4-NC was not expressive (SPF=3.35+/-0.02), suggesting the predominance of its antioxidant activity.

Antioxidant activity of aryltetralone lignans and derivatives from Virola sebifera (Aubl.).

Aryltetralone lignans bearing methylenedioxy groups (1a-b; 2a-b) were isolated from seeds of Virola sebifera. Their antioxidant activities were evaluated by inhibition of lipid peroxidation as indicated by TBARS and chemiluminescence emission (CL) assays. The lignan 1c, 'having a 2'-hydroxy-4',5'-methylenedioxyphenyl group, was the most active compound with TBARS/CL Q 1/2 values of 0.89 and 0.10 microg/mL, respectively. The catechol derivatives 3 and 4, obtained by demethylenation of lignans 1a and 2a, were of similar activity to 1c, and all were much more effective as antioxidants than alpha-tocopherol.

Aging and oxidative stress.

The scientific establishment has been discussing the relationship between aging and oxidative stress for quite some time now. While we are still far from a general agreement about this subject, there is an impressive amount of data collected that can be used to draw a compelling picture of the events that take place during the human aging process and their correlation with the oxidant status of the organism. In this review, we bring forth the results of some key studies that can help to elucidate the aging-oxidative stress puzzle, as well as to explain which are the fundamental events in this interplay and why their causal relationships remain so elusive. We also put forward here data on the systemic oxidative stress status of a group of 503 healthy human subjects. The data consist of the plasma levels of TBARS and of the nutritional antioxidants, alpha-tocopherol, beta-carotene and ascorbic acid, and of the activity of the antioxidant enzymes, Cu, Zn-superoxide dismutase, catalase and glutathione peroxidase, of red blood cells. The data indicate that a moderate situation of oxidative stress gradually develops during human aging.

Blood and aqueous humour antioxidants in cataractous poodles.

BACKGROUND: Cataract is an important cause of blindness in dogs and frequently develops in young animals of certain breeds, such as the English cocker spaniel and the poodle. Protein oxidation is one of the mechanisms involved in lens opacification and may be causally related to depleted or diminished endogenous antioxidant defences. We evaluated the levels of enzymatic and nonenzymatic antioxidants in blood and aqueous humour of cataractous poodles in comparison to noncataractous poodles. METHODS: We studied 35 cataractous poodles aged 2 to 11 years, 14 noncataractous poodles and 15 noncataractous mixed-breed dogs. The activity of erythrocyte antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase [G6PD]) was evaluated in 18 cataractous poodles and 14 noncataractous poodles. We evaluated ascorbic acid levels in plasma of all animals and in aqueous humour of cataractous poodles and mixed-breed dogs. The dogs were deprived of food for 12 hours before sampling. Blood samples were obtained from the jugular vein before and during anesthesia. Aqueous humour samples were obtained just before the anterior chamber was opened. RESULTS: The activity of superoxide dismutase, G6PD and catalase was significantly higher in noncataractous poodles than in cataractous poodles (p < or = 0.05). The activity of glutathione peroxidase was lower in noncataractous poodles than in cataractous poodles, but not significantly so. There was no difference in mean plasma ascorbic acid concentration between cataractous poodles (21.3 microM [standard deviation (SD) 7.4 microM]), noncataractous poodles (21.6 microM [SD 7.4 microM]) and non-cataractous mixed-breed dogs (25.8 microM [SD 7.5 microM]). Similarly, there was no difference in mean aqueous humour ascorbic acid concentration between cataractous poodles (191.7 microM [SD 62.0 microM] and noncataractous mixed-breed dogs (215.7 microM [SD 91.8 microM]). INTERPRETATION: The results indicate that, at least in the population studied here, no correlation exists between the onset of cataract and ascorbic acid concentration in blood and aqueous humour. The decreased activity of antioxidant enzymes may explain in part the onset of cataract in poodles.

Pothomorphe umbellata extract prevents alpha-tocopherol depletion after UV-irradiation.

In this work we evaluated the influence of topical application of P. umbellata root extract gel, containing 0.1% of 4-nerolidylcathecol, on the antioxidant network in UV-induced oxidative damage in hairless mouse skin. The UV-irradiation had no influence on ascorbic acid levels or on the antioxidant enzyme (superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase) activities, but topical P. umbellata treatment protected alpha-tocopherol from being depleted after UV-irradiation. alpha-Tocopherol concentration decreased significantly (approximately 40%, P < 0.01) in the irradiated control groups, whereas in the P. umbellata-treated group, alpha-tocopherol was totally preserved (approximately 100%, P > 0.05). These data demonstrate that P. umbellata may be successfully used as a topical photoprotective agent.

Evaluation of percutaneous absorption of 4-nerolidylcathecol from four topical formulations.

Antioxidants such as vitamins E and C are known to play a significant role in ameliorating or preventing oxidative damage to the skin. However, to provide a satisfactory protection they must first permeate the skin, which serves as a permeation barrier. In this study we evaluated the influence of three different formulations (gel, gel-emulsion and emulsion) on the percutaneous absorption of 4-nerolidylcathecol, an antioxidant compound isolated from Pothomorphe umbellata root extracts. Also, the absorption of the isolated 4-nerolidylcathecol was compared with its absorption when dried P. umbellata root ethanolic extract was incorporated into a gel formulation. The 'lag time method' was employed for the analysis of the in vitro permeation data. All formulations showed satisfactory percutaneous penetration with the 4-nerolidylcathecol-gel presenting a higher rate of penetration leading to higher dry drug levels in the tissue.

Antioxidant activity of ethanolic extracts of Pothomorphe umbellata L. Miq. (Pariparoba)

Oxidative stress has been implicated in many pathological conditions such as cancer, aging inflammation and cell death. The Brazilian flora is particularly rich in medicinal plants employed for many purposes. Among them the Piperaceae family and specially the "pariparobas" are widely used in the treatment of liver diseases. In vitro antioxidant activity of Pothomorphe umbellata L. Miq. was evaluated and compared with that of Piper regnellii, another plant from the Piperaceae family commonly used as it were P. umbellata. A purified fraction of the ethanolic extract of P. umbellata, containing 4-nerolidylcatechol was also assayed for antioxidant activity and compared with that of alpha-tocopherol. Rat brain homogenates were incubated with increasing aliquots of crude extracts of different parts of the plants or 4-nerolidylcatechol/alpha-tocopherol for 1 h at 37 degrees Celsius. Both malondialdehyde (MDA) and chemiluminescence (CL) were assayed to evaluate brain tissue autoxidation. The Q1/2 for MDA assay for root, stem and leaves were 4.4, 19.3 and 38.5 mug/mL for P. umbellata and 26.0,64.4 and 13.3 mug/mL for P regnellii, respectively. Calculated MDA and CL Q1/2 values for 4-nerolidylcatechol and alpha-tocopherol were O.75 and O.68 muM for 4-nerolidylcatechol and 14.4 and 1O.9 muM for alpha-tocopherol, respectively. These results indicate high antioxidant activity of P. umbellata root extract as compared to that of vitamin E, which was attributed to the presence of 4-nerolidylcatecho1.