3T3 NRU Research Articles

P16-44: Evaluation of phototoxic potential of seven solvents using in silico derek and in vitro 3T3 NRU method

P16-44: Evaluation of phototoxic potential of seven solvents using in silico derek and in vitro 3T3 NRU method

2-Alkyl-Substituted-4-Amino-Thieno[2,3-d]Pyrimidines: Anti-Proliferative Properties to In Vitro Breast Cancer Models.

Thienopyrimidines are structural analogs of quinazolines, and the creation of new 2-alkyl derivatives of ethyl 4-aminothienopyrimidine-6-carboxylates for the study of their anti-proliferative properties is of great pharmacological interest. Some 2-alkyl-4-amino-thieno[2,3-d]pyrimidines 2-5 were synthesized, and their cyto- and phototoxicity against BALB 3T3 cells were established by an in vitro 3T3 NRU test. The obtained results indicate that the tested compounds are not cytotoxic or phototoxic, and that they are appropriate to be studied for their anti-proliferative and anti-tumor properties. The anti-proliferative potential of the compounds was investigated on MCF-7 and MDA-MB-231 cancer cells, as well as a MCF-10A cell line (normal human mammary epithelial cells). The most toxic to MCF-7 was thienopyrimidine 3 with IC50 13.42 μg/mL (IC50 0.045 μM), followed by compound 4 (IC50 28.89 μg/mL or IC50 0.11 μM). The thienopyrimidine 4 revealed higher selectivity to MCF-7 and lower activity (IC50 367 μg/mL i.e., 1.4 μM) than compound 3 with MCF-10A cells. With respect to MDA-MB-231 cells, ester 2 manifested the highest effect with IC50 52.56 μg/mL (IC50 0.16 μM), and 2-ethyl derivative 4 revealed IC50 62.86 μg/mL (IC50 0.24 μM). It was estimated that the effect of the substances on the cell cycle progression was due to cell cycle arrest in the G2 stage for MDA-MB-231, while arrest in G1 was detected for the estrogen (ER)-positive MCF-7 cell line. The tested compound's effects on the change of the zeta potential in the tumorigenic cells utilized in this study were determined. The calculation which we performed of the physicochemical properties and pharmacokinetic parameters influencing the biological activity suggested high intestinal absorption, as well as drug-likeness.

LB1759 Evaluation of LED irradiation effect to retinol by modified in vitro 3T3 NRU phototoxicity assay

LB1759 Evaluation of LED irradiation effect to retinol by modified in vitro 3T3 NRU phototoxicity assay

Construction of tea tree oil/salicylic acid/palygorskite hybrids for advanced antibacterial and anti-inflammatory performance.

This study describes the construction of a tailor-made clay-based hybrid with advanced dermocompatibility, antibacterial and anti-inflammatory performance by incorporating tunable ratios of tea tree oil (TTO) and salicylic acid (SA) into the naturally occurring porous structure of palygorskite (Pal). Among the three TTO/SA/Pal (TSP) systems constructed, TSP-1 with a TTO : SA ratio of 1 : 3 demonstrated the lowest 3T3 NRU predicted acute oral toxicity and dermal HaCaT cytotoxicity as well as the most pronounced antibacterial activity with a selective inhibitory action against the pathogens (E. coli, P. acnes and S. aureus) over the beneficial (S. epdermidis) species inhabiting on the human skin. Also noticeable is that exposure of these skin commensal bacteria to TSP-1 prevented the antimicrobial resistance evolution compared to the conventional antibiotic ciprofloxacin. Mechanistic investigation of its antibacterial modes of action revealed a synergy between the TTO and SA loadings on the Pal supports in reactive oxygen production, causing oxidative damage to bacterial cell membranes and increased leakage of intracellular compounds. Additionally, TSP-1 significantly decreased the proinflammatory cytokines of IL-1β, IL-6, IL-8, and TNF-α in a bacterial lipopolysaccharide-stimulated differentiated THP-1 macrophage model, showing the potential to inhibit inflammatory responses in bacterial infections. Overall, this is the first report exploring the potential of constructing clay-based organic-inorganic hybrids as alternatives to antibiotics to combat bacterial resistance with advanced compatibility and anti-inflammatory benefits that are desired for the development of topically applied biopharmaceuticals.

Absence of phototoxicity/photoirritation potential of bergamottin determined In Vitro using OECD TG 432

The phototoxic potential of a number of furocoumarins is well established. On the other hand, studies have shown that bergamottin, a furocoumarin containing a bulky, hydrophobic side chain, has significantly less or is even absent of phototoxicity potential. The OECD Test Guideline 432 3T3/Neutral Red Uptake (NRU) in vitro phototoxicity test has shown to be a highly predictive test for identifying compounds that exhibit no phototoxicological potential. In this study using OECD 432, the established phototoxic furocoumarin 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP) and psoralen were phototoxic, whereas bergamottin showed no phototoxic potential. When compared to 5-MOP, 8-MOP and psoralen, bergamottin was clearly negative at molar-adjusted concentrations that were more than 9 times higher than those that produced phototoxicity in 8-MOP; nearly 16 times than those for psoralen and more than 36 times higher than those for 5-MOP. These data using in vitro 3T3 NRU Phototoxicity Test (OECD 432) are supportive of earlier studies showing bergamottin does not exhibit phototoxicological properties. The detection and quantification of bergamottin should therefore not contribute to the potential marker furocoumarins for risk management interventions intended to reduce the phototoxicity of natural furocoumarin containing preparations.

Safety Assessment of Ethanolic Extract of Padina gymnospora as a Cosmetic Ingredient

Purpose: In a previous study, we identified the skin-whitening effect of the ethanolic extract of Padina gymnospora. The present study was performed to confirm the safety of the extract in animal replacement tests.Methods: To evaluate the safety of the extract of Padina gymnospora, the photosensitivity test (Harber test), in vitro 3T3 neutral red uptake (3T3 NRU) phototoxicity test, local lymph node assay (5-bromo-2'-deoxyuridine enzyme-linked immunosorbent assay), acute oral toxicity test, and reconstructed human epidermis (RHE) test were used. All experiments followed the guidelines of the Korean Ministry of Food and Drug Safety and were conducted by a GLP-certified organization (Chemon Inc.).Results: The extract of Padina gymnospora was not photosensitive: 0% photosensitization was detected (I grade: very weak). In the 3T3 NRU phototoxicity test, the relative viability of the extract-treated cells was higher than the guideline level; thus, the extract was classified as non-phototoxic. Treatment with the extract did not trigger skin irritation in the RHE test model and did not cause skin sensitization in the local lymph node assay. Finally, oral administration of the extract to rats indicated that it was not a harmful material as the LD<sub>50</sub> was estimated at >2,000 mg/kg.Conclusion: The ethanolic extract of Padina gymnospora was demonstrated to be safe when applied to the skin. Taken together with our previous study of its efficacy, we conclude that this extract has the potential for use as a cosmetic ingredient.

Synthesis and Biological Studies on (KLAKLAK)2-NH2 Analog Containing Unnatural Amino Acid β-Ala and Conjugates with Second Pharmacophore.

(1) Background: Peptides are good candidates for anticancer drugs due to their natural existence in the body and lack of secondary effects. (KLAKLAK)2 is an antimicrobial peptide that also shows good anticancer properties. (2) Methods: The Solid Phase Peptide Synthesis (Fmoc-strategy) was used for the synthesis of target molecules, analogs of (KLAKLAK)2-NH2. The purity of all compounds was monitored by HPLC, and their structures were proven using mass spectrometry. Cytotoxicity and antiproliferative effects were studied using 3T3 NRU and MTT tests, respectively. For determination of antimicrobial activity, the disc-diffusion method was used. Hydrolytic stability at three pH values, which mimic the physiological pH in the body, was investigated by means of the HPLC technique. (3) Results: A good selective index against MCF-7 tumor cell lines, combined with good cytotoxicity and antiproliferative properties, was revealed for conjugates NphtG-(KLAKLAK)2-NH2 and Caf-(KLAKLAK)2-NH2. The same compounds showed very good antifungal properties and complete hydrolytic stability for 72 h. The compound Caf-(KLβ-AKLβ-AK)2-NH2 containing β-Ala in its structures exhibited good antimicrobial activity against Escherichia coli K12 407 and Bacillus subtilis 3562, in combination with very good antiproliferative and cytotoxic properties, as well as hydrolytic stability. (4) Conclusions: The obtained results reveal that all synthesized conjugates could be useful for medical practice as anticancer or antimicrobial agents.

Machine learning prediction of UV\u2013Vis spectra features of organic compounds related to photoreactive potential

Machine learning (ML) algorithms were explored for the classification of the UV–Vis absorption spectrum of organic molecules based on molecular descriptors and fingerprints generated from 2D chemical structures. Training and test data (~ 75 k molecules and associated UV–Vis data) were assembled from a database with lists of experimental absorption maxima. They were labeled with positive class (related to photoreactive potential) if an absorption maximum is reported in the range between 290 and 700 nm (UV/Vis) with molar extinction coefficient (MEC) above 1000 Lmol−1 cm−1, and as negative if no such a peak is in the list. Random forests were selected among several algorithms. The models were validated with two external test sets comprising 998 organic molecules, obtaining a global accuracy up to 0.89, sensitivity of 0.90 and specificity of 0.88. The ML output (UV–Vis spectrum class) was explored as a predictor of the 3T3 NRU phototoxicity in vitro assay for a set of 43 molecules. Comparable results were observed with the classification directly based on experimental UV–Vis data in the same format.

In chemico sequential testing strategy for assessing the photoallegic potential

Several non-animal testing methods to assess photoallergic potential have been developed so far, while none of them have yet to be validated and regulatory accepted. Currently, some photoreactivity assays such as UV-VIS spectral analysis and ROS assay are generally used for initial photosafety assessments because of their high sensitivity. However, they have a low specificity, generating a high percentage of false positive results, and the development of a follow-up assessment method is desired. Therefore, this study aimed to develop an in chemico photoallergy testing method, photo-direct peptide reactivity assay (photo-DPRA). Based on photosafety information, 34 photoallergens and 16 non-photoallergens were selected and subjected to UV-VIS spectral analysis, ROS/micellar ROS assays, photo-DPRA, sequential testing strategy (STS) consisting of all three methods, and 3T3 neutral red uptake phototoxicity testing (3T3 NRU PT). Combination of the methods addressing the key events of photoallergy exhibited high prediction performance. Our results showed the proposed strategy would be useful to predict the photoallergic potential of chemicals as the follow-up assessment for false positive chemicals by UV/VIS spectral analysis and ROS assay.

A cross-industry survey on photosafety evaluation of pharmaceuticals after implementation of ICH S10

A cross-industry survey was conducted by EFPIA/IQ DruSafe in 2018 to provide information on photosafety evaluation of pharmaceuticals after implementation of ICH S10. This survey focused on the strategy utilized for photosafety risk assessment, the design of nonclinical (in vitro and in vivo) and clinical evaluations, the use of exposure margins in risk assessment, and regulatory interactions. The survey results indicated that a staged approach for phototoxicity assessment has been widely accepted by regulatory authorities globally. The OECD-based 3T3 NRU Phototoxicity Test is the most frequently used in vitro approach. Modifications to this assay suggested by ICH S10 are commonly applied. For in-vitro-positives, substantial margins from in vitro IC50 values under irradiation to Cmax (clinical) have enabled further development without the need for additional photosafety data. In vivo phototoxicity studies typically involve dosing rodents and exposing skin and eyes to simulated sunlight, and subsequently evaluating at least the skin for erythema and edema. However, no formal guidelines exist and protocols are less standardized across companies. A margin-of-safety approach (based on Cmax at NOAEL) has been successfully applied to support clinical development. Experience with dedicated clinical phototoxicity studies was limited, perhaps due to effective de-risking approaches employed based on ICH S10.

124-LB: Development of IDG-16177, a Selective and Safe GPR40 Agonist for the Treatment of Type 2 Diabetes

GPR40 has been considered a potential therapeutic target for type 2 diabetes because activation of GPR40 stimulates insulin secretion when glucose levels increased. Fasiglifam, a GPR40 agonist, was withdrawn from clinical development in Phase III due to DILI. Therefore, we evaluated the safety profiles of IDG-16177, a novel GPR40 agonist. The potential for IDG-16177 to have off-target effects was assessed in a panel of 173 binding assays. 10 μM IDG-16177 demonstrated activity (>50% inhibition) against DP, EP2, EP3 and EP4 with 81, 83, 57 and 67 % inhibition, respectively. In a functional assay against the same targets, IDG-16177 was inactive in agonist and antagonist mode except for DP with 62.2% activity inhibition at a concentration of 10 μM. IDG-16177 and fasiglifam showed the similar level of hepatotoxic response in HμRELToxTM assay. Formation of reactive metabolite and covalent binding to proteins was evaluated in human hepatocytes. IDG-16177 shows lower covalent binding burden at expected human efficacious dose (0.3~1 mg) than fasiglifam. Transporter inhibitory potential of IDG-16177 was assessed in hepatic transporter-expressing membrane vesicles. IDG-16177 and fasiglifam showed the similar inhibition level of BSEP, MRP2, MRP3, and MRP4. But clinically predicted plasma concentration of IDG-16177 is lower than that of fasiglifam, so the safety margin of IDG-16177 is wider than that of fasiglifam. A core battery of safety pharmacology was evaluated and IDG-16177 did not induce adverse effect in all studies. A 4-week toxicity study was conducted in rats and monkeys, and the liver was determined as the target organ in monkeys. The NOAEL was over 60-fold than in vivo efficacy dose. IDG-16177 was not genotoxic in Ames test, in vitro and in vivo micronucleus test. And no phototoxicity was observed in in vitro 3T3 NRU study. These results shows that the potential for IDG-16177, a safe and effective GPR40 agonist, to treat patients with type 2 diabetes. Disclosure J. Yoon: None. J. Kim: None. K. An: None. C. Hong: None. H. Kwak: None. I. Je: None. H. Song: None. H. Song: None. J. Kim: None. S. Lee: None. C. Shin: None. Y. Jun: None. D. Hong: None. D. Lee: None. E. Jang: None.

In Vitro Evaluation of the Photoprotective Potential of Quinolinic Alkaloids Isolated from the Antarctic Marine Fungus Penicillium echinulatum for Topical Use.

Marine-derived fungi proved to be a rich source of biologically active compounds. The genus Penicillium has been extensively studied regarding their secondary metabolites and biological applications. However, the photoprotective effects of these metabolites remain underexplored. Herein, the photoprotective potential of Penicillium echinulatum, an Antarctic alga-associated fungus, was assessed by UV absorption, photostability study, and protection from UVA-induced ROS generation assay on human immortalized keratinocytes (HaCaT) and reconstructed human skin (RHS). The photosafety was evaluated by the photoreactivity (OECD TG 495) and phototoxicity assays, performed by 3T3 neutral red uptake (3T3 NRU PT, OECD TG 432) and by the RHS model. Through a bio-guided purification approach, four known alkaloids, (-)-cyclopenin (1), dehydrocyclopeptine (2), viridicatin (3), and viridicatol (4), were isolated. Compounds 3 and 4 presented absorption in UVB and UVA-II regions and were considered photostable after UVA irradiation. Despite compounds 3 and 4 showed phototoxic potential in 3T3 NRU PT, no phototoxicity was observed in the RHS model (reduction of cell viability < 30%), which indicates their very low acute photoirritation and high photosafety potential in humans. Viridicatin was considered weakly photoreactive, while viridicatol showed no photoreactivity; both compounds inhibited UVA-induced ROS generation in HaCaT cells, although viridicatol was not able to protect the RHS model against UVA-induced ROS production. Thus, the results highlighted the photoprotective and antioxidant potential of metabolites produced by P. echinulatum which can be considered a new class of molecules for photoprotection, since their photosafety and non-cytotoxicity were predicted using recommended in vitro methods for topical use.

In vitro assessment of the photo(geno)toxicity associated with Lapatinib, a Tyrosine Kinase inhibitor.

The epidermal growth factor receptors EGFR and HER2 are the main targets for tyrosine kinase inhibitors (TKIs). The quinazoline derivative lapatinib (LAP) is used since 2007 as dual TKI in the treatment of metastatic breast cancer and currently, it is used as an oral anticancer drug for the treatment of solid tumors such as breast and lung cancer. Although hepatotoxicity is its main side effect, it makes sense to investigate the ability of LAP to induce photosensitivity reactions bearing in mind that BRAF (serine/threonine-protein kinase B-Raf) inhibitors display a considerable phototoxic potential and that afloqualone, a quinazoline-marketed drug, causes photodermatosis. Metabolic bioactivation of LAP by CYP3A4 and CYP3A5 leads to chemically reactive N-dealkylated (N-LAP) and O-dealkylated (O-LAP) derivatives. In this context, the aim of the present work is to explore whether LAP and its N- and O-dealkylated metabolites can induce photosensitivity disorders by evaluating their photo(geno)toxicity through in vitro studies, including cell viability as well as photosensitized protein and DNA damage. As a matter of fact, our work has demonstrated that not only LAP, but also its metabolite N-LAP have a clear photosensitizing potential. They are both phototoxic and photogenotoxic to cells, as revealed by the 3T3 NRU assay and the comet assay, respectively. By contrast, the O-LAP does not display relevant photobiological properties. Remarkably, the parent drug LAP shows the highest activity in membrane phototoxicity and protein oxidation, whereas N-LAP is associated with the highest photogenotoxicity, through oxidation of purine bases, as revealed by detection of 8-Oxo-dG.

Computational Investigation of Drug Phototoxicity: Photosafety Assessment, Photo-Toxophore Identification, and Machine Learning.

One of the most appreciated capabilities of computational toxicology is to support the design of pharmaceuticals with reduced toxicological hazard. To this end, we have strengthened our drug photosafety assessments by applying novel computer models for the anticipation of in vitro phototoxicity and human photosensitization. These models are typically used in pharmaceutical discovery projects as part of the compound toxicity assessments and compound optimization methods. To ensure good data quality and aiming at models with global applicability we separately compiled and curated highly chemically diverse data sets from 3T3 NRU phototoxicity reports (450 compounds) and clinical photosensitization alerts (1419 compounds) which are provided as supplements. The latter data gives rise to a comprehensive list of explanatory fragments for visual guidance, termed phototoxophores, by application of a Bayesian statistics approach. To extend beyond the domain of well sampled fragments we applied machine learning techniques based on explanatory descriptors such as pharmacophoric fingerprints or, more important, accurate electronic energy descriptors. Electronic descriptors were extracted from quantum chemical computations at the density functional theory (DFT) level. Accurate UV/vis spectral absorption descriptors and pharmacophoric fingerprints turned out to be necessary for predictive computer models, which were both derived from Deep Neural Networks but also the simpler Random Decision Forests approach. Model accuracies of 83-85% could typically be reached for diverse test data sets and other company in-house data, while model sensitivity (the capability of correctly detecting toxicants) was even better, reaching 86%-90%. Importantly, a computer model-triggered response-map allowed for graphical/chemical interpretability also in the case of previously unknown phototoxophores. The photosafety models described here are currently applied in a prospective manner for the hazard identification, prioritization, and optimization of newly designed molecules.

Implementation of an in vitro methodology for phototoxicity evaluation in a human keratinocyte cell line

To assess photoxicity, several in vitro methods using different cellular models have been developed for preclinical testing. Over prediction of the in vivo photosafety hazard has been however appointed. Herein, we describe the implementation and validation of an in vitro methodology for phototoxicity evaluation based on the 3T3 neutral red uptake phototoxicity test using the HaCaT human keratinocyte cell line, and UVA/UVB radiation. Known positive (5-methoxypsoralen, chlorpromazine, and quinine) and negative (acetyl salicylic acid, hexachlorophene, and sodium lauryl sulphate) controls were tested together with a set of chemical currently used in cosmetic/pharmaceutical formulations. Apart from the advantage of using a cell line of human origin, these cells were generally more resistant to the cytotoxic effects of the test substances relative to the 3T3 mouse fibroblasts when exposed to an UVA irradiation dose of 1.7 mW/cm2. Therefore, this HaCaT NRU assay provides a more realistic experimental model that overcomes the over/high sensitivity frequently noted with the 3T3 NRU assay and that is more consistent with the human in vivo situation. Using a more representative method can prevent time-consuming and expensive in vivo testing in both animal models and humans that can significantly delay the clinical development of new chemicals.

Spirulina, Palmaria Palmata, Cichorium Intybus, and Medicago Sativa extracts in cosmetic formulations: an integrated approach of in vitro toxicity and in vivo acceptability studies

Background/Aims: The selection of suitable raw materials in the cosmetic research and development is a key point, not only in order to obtain the expected results but also to avoid undesirable side effects. This study evaluated the in vitro toxicity potential of four different plant extracts and their in vivo acceptability studies. Methods: Spirulina, Palmaria palmata, Cichorium intybus and Medicago sativa extracts were analysed alone or in combination and added in cosmetic formulations. The in vitro toxicity evaluation, Hen’s Egg Chorioallantoic Membrane Test (HET-CAM) and 3T3 NRU phototoxicity test were performed to evaluate in vitro potential ocular irritation and photo safety, respectively. Twenty subjects were enrolled in the acceptability studies, who were evaluated for the absence of harmful effects of the formulation by visual assessment and by transepidermal water loss, a biophysical technique, for 30 days. Results: HET-CAM assay showed that the studied extracts added to a gel-cream formulation had no irritant potential. In addition, the combination of Palmaria palmata, alfalfa and chicory extracts did not show phototoxic potential in vitro. Acceptability studies showed that the formulation containing the four extracts combined did not provoke any transepidermal water loss (TEWL) alteration, sensory irritation or erythema in the forearms for the period of analysis. Conclusion: The studied active ingredients, alone or in combination, present no cytotoxicity potential and when added to a gel-cream formulation had no irritant potential in vitro. These results predicting no harmful effects were confirmed in the acceptability tests, which showed no alteration on skin barrier function and no report of irritation perception of sign of erythema, suggesting the potential of these extracts for the development of safe cosmetic products.

Topical formulation of quercetin encapsulated in natural lipid nanocarriers: Evaluation of biological properties and phototoxic effect

Skin aging might happen due to extrinsic and intrinsic factors that usually can induce the increase of free radicals and generate oxidative stress, which lead to skin alterations. Thus, there is a search for antioxidant substances that can control these effects. Quercetin (QT) is a flavonoid with antioxidant potential however presents poor percutaneous permeation, low stability and phototoxicity. Therefore, the encapsulation in nanoparticles is an interesting strategy to overcome these challenges. Nanostructured lipid carriers (NLC) is a promising type of vehicle that can improve drug penetration on skin and enhance the entrapment efficiency as well as improve the drug stability. These nanoparticles can be produced using natural lipids with biological properties resulting in a carrier with biological activities. The aim of this study was to produce NLC to load QT enhancing its permeation and obtaining an effective and safe topical formulation. The NLC were characterized regarding their size, zeta potential, entrapment efficiency, thermal behavior, morphology and evaluation of the biological properties using in vitro methods to analyze the antioxidant activity, skin permeation, antiallergic potential, cytotoxicity and phototoxicity potential on monolayer (HaCaT cells and 3T3 NRU PT) and on reconstructed human skin model (H3D-PT). The average size of QT-NLC was 130 nm with low polydispersity index (PdI) (~0.260), and negative zeta potential (around of −13 mV). Through the thermal behavior analysis, the nanoparticle exhibited a low recrystallization index (13.03%), which is important to obtain high entrapment efficiency (97.42%) and avoid drug expulsion during the storage time. The nanoparticles showed a homogeneous morphology and were very stable regarding to size and PdI over to 120 days. On terms of biological properties QT-NLC presented antioxidant activity, enhanced penetration of quercetin in the skin and showed an antiallergic potential. Furthermore, in the reconstructed human skin model that consider viable epidermis bioavailability due to the presence of stratum corneum, it was observed that the topical formulation of QT-NLC presented no phototoxic potential. Therefore, the developed nanostructure is a vehicle with potential for topical administration of quercetin.

Chemical tuning for potential antitumor fluoroquinolones

Phototoxic effects of 6,8 dihalogenated quinolones confers to this type of molecules a potential property as photochemotherapeutic agents. Two photodehalogenation processes seem to be involved in the remarkable photoinduced cellular damage. In this context, a new 6,8 dihalogenated quinolone 1 (1-methyl-6,8-difluoro-4-oxo-7-aminodimethyl-1,4-dihydroquinoline-3-carboxylic acid) was synthetized looking for improving the phototoxic properties of fluoroquinolones (FQ) and to determine the role of the photodegradation pathways in the FQ phototoxicity. With this purpose, fluorescence emissions, laser flash photolysis experiments and photodegradation studies were performed with compound 1 using 1-ethyl-6,8-difluoro-4-oxo-7-aminodimethyl-1,4-dihidroquinoline-3-carboxylic acid (2) and lomefloxacin (LFX) as reference compounds. The shortening of alkyl chain of the N(1) of the quinolone ring revealed a lifetime increase of the reactive aryl cation generated from photolysis of the three FQ and a significant reduction of the FQ photodegradation quantum yield. The fact that these differences were smaller when the same study was done using a hydrogen donor solvent (ethanol-aqueous buffer, 50/50 v/v) evidenced the highest ability of the reactive intermediate arising from 1 to produce intermolecular alkylations. These results were correlated with in vitro 3T3 NRU phototoxicity test. Thus, when Photo-Irritation-Factor (PIF) was determined for 1, 2 and LFX using cytotoxicity profiles of BALB/c 3T3 fibroblasts treated with each compound in the presence and absence of UVA light, a PIF more higher than 30 was obtained for 1 while the values for 2 and LFX were only higher than 8 and 10, respectively. Thereby, the present study illustrates an approach to modulate the photosensitizing properties of FQ with the purpose to improve the chemotherapeutic properties of antitumor quinolones. Moreover, the results obtained in this study also evidence that the key pathway responsible for the phototoxic properties associated with dihalogenated quinolones is the aryl cation generation.

Toxicity of food contact paper evaluated by combined biological and chemical methods

The study was focused on assessment of potential health risks of paper-based food contact materials (FCMs) in a step-wise approach using three toxicological bioassays in vitro and chemical analyses of migrating contaminants. 3T3 NRU cytotoxicity test showed high sensitivity to detect basal toxicity of FCMs extracts and served as a first-line test for selection of samples for further testing. The reconstructed human intestine model EpiIntestinal showed more realistic tissue response than cell culture monolayer and higher resistance despite prolonged exposure to the selected 6 samples, i.e. negligible decrease of viability and intestinal penetration, nevertheless an increase of IL-8 after exposure to black printed sample extract. Yeast based assays identified weak agonistic/antagonostic activity to human androgen receptor of the black printed sample. In accordance with the biological effects, the targeted LC and GC analytical methods confirmed the presence of high amounts of phthalates, photoinitiators and PAHs that could justify the hazard of the black printed sample. Heavily printed uncoated FCMs are recognized not to be suitable for direct contact with food. The selected bioassays and chemical analyses might be useful tools to detect targeted biological effects of xenobiotics suspected to contribute to human exposure from food.

Chemical Characterization and Biotechnological Applicability of Pigments Isolated from Antarctic Bacteria.

Considering the global trend in the search for alternative natural compounds with antioxidant and sun protection factor (SPF) boosting properties, bacterial carotenoids represent an opportunity for exploring pigments of natural origin which possess high antioxidant activity, lower toxicity, no residues, and no environmental risk and are readily decomposable. In this work, three pigmented bacteria from the Antarctic continent, named Arthrobacter agilis 50cyt, Zobellia laminarie 465, and Arthrobacter psychrochitiniphilus 366, were able to withstand UV-B and UV-C radiation. The pigments were extracted and tested for UV absorption, antioxidant capacity, photostability, and phototoxicity profile in murine fibroblasts (3T3 NRU PT-OECD TG 432) to evaluate their further potential use as UV filters. Furthermore, the pigments were identified by ultra-high-performance liquid chromatography-photodiode array detector-mass spectrometry (UPLC-PDA-MS/MS). The results showed that all pigments presented a very high antioxidant activity and good stability under exposure to UV light. However, except for a fraction of the A. agilis 50cyt pigment, they were shown to be phototoxic. A total of 18 different carotenoids were identified from 23 that were separated on a C18 column. The C50 carotenes bacterioruberin and decaprenoxanthin (including its variations) were confirmed for A. agilis 50cyt and A. psychrochitiniphilus 366, respectively. All-trans-bacterioruberin was identified as the pigment that did not express phototoxic activity in the 3T3 NRU PT assay (MPE < 0.1). Zeaxanthin, β-cryptoxanthin, β-carotene, and phytoene were detected in Z. laminarie 465. In conclusion, carotenoids identified in this work from Antarctic bacteria open perspectives for their further biotechnological application towards a more sustainable and environmentally friendly way of pigment exploitation.