Antioksidansi i spojevi selenija inhibiraju toksično djelovanje 3,5-dimetilaminofenola na epitelne bubrežne stanice u ljudi

Exposure to alkyl anilines may lead to bladder cancer, which is the second most frequent cancer of the urogenital tract. 3,5-dimethylaniline is highly used in industry. Studies on its primary metabolite 3,5-dimethylaminophenol (3,5-DMAP) showed that this compound causes oxidative stress, changes antioxidant enzyme activities, and leads to death of different mammalian cells. However, there is no in vitro study to show the direct effects of 3,5-DMAP on human bladder and urothelial cells. Selenocompounds are suggested to decrease oxidative stress caused by some chemicals, and selenium supplementation was shown to reduce the risk of bladder cancer. The main aim of this study was to investigate whether selenocompounds organic selenomethionine (SM, 10 μmol/L) or inorganic sodium selenite (SS, 30 nmol/L) could reduce oxidative stress, DNA damage, and apoptosis in UROtsa cells exposed to 3,5-DMAP. 3,5-DMAP caused a dose-dependent increase in intracellular generation of reactive oxygen species, and its dose of 50 μmol/L caused lipid peroxidation, protein oxidation, and changes in antioxidant enzyme activities in different cellular fractions. The comet assay also showed single-strand DNA breaks induced by the 3,5-DMAP dose of 50 μmol/L, but no changes in double-strand DNA breaks. Apoptosis was also triggered. Both selenocompounds provided partial protection against the cellular toxicity of 3,5-DMAP. Low selenium status along with exposure to alkyl anilines can be a major factor in the development of bladder cancer. More mechanistic studies are needed to specify the role of selenium in bladder cancer.Izloženost alkilnim anilinima može uzrokovati rak mokraćnoga mjehura, koji je drugi po redu po učestalosti raka mokraćnospolnog sustava. 3,5-dimetilanilin često se rabi u industrijskoj proizvodnji, a istraživanja njegova primarnog metabolita, 3,5-dimetilaminofenola (3,5-DMAP), pokazuju da on uzrokuje oksidacijski stres i promjene u aktivnosti antioksidacijskih enzima te u konačnici dovodi do smrti raznih stanica u sisavaca. Dosad, međutim, nije provedeno nijedno istraživanje njegovih izravnih učinaka na epitelne stanice mokraćnoga mjehura i bubrega u ljudi. Za spojeve selenija smatra se da smanjuju oksidacijski stres različitih kemikalija te da dopuna prehrane selenijem smanjuje rizik od raka mokraćnoga mjehura. Primarni je cilj ovoga istraživanja bio utvrditi može li organski spoj selenija selenometionin (SM, 10 μmol/L), odnosno anorganski spoj natrijev selenit (SS, 30 nmol/L], smanjiti oksidacijski stres, oštećenje DNA i apoptozu u UROtsa stanicama izloženima 3,5-dimetilaminofenolu. Jednosatna izloženost stanica 3,5-DMAP-u dovela je do povećanja razina reaktivnih kisikovih spojeva (ROS), lipidne peroksidacije, oksidacije bjelančevina te do promjena u aktivnosti antioksidacijskih enzima u staničnoj citoplazmi i jezgri, ovisno o primijenjenoj dozi. Osim toga, komet-testom su utvrđeni jednolančani, ali ne i dvolančani lomovi DNA. Također, 3,5-DMAP uzrokovao je apoptozu stanica. Oba su spoja selenija pružila djelomičnu zaštitu od njegova toksičnoga djelovanja. Nedostatak selenija pri izloženosti alkilnim anilinskim spojevima stoga može odigrati značajnu ulogu u nastanku raka mokraćnog mjehura. Potrebna su daljnja istraživanja mehanizama djelovanja selenija u njegovu sprječavanju

Toxicité in vitro de nanoparticules de dioxyde de titane sur des cellules pulmonaires humaines - impact des caractéristiques physicochimiques

With the growing development of nanoscience and nanotechnology, concerns on the potential health effect of nanoparticles have increased. Titanium dioxide nanoparticles (TiO2 NPs) are widely used in a wide variety of industrial applications, mainly because of their unique properties such as their small size, high refractive index, or photocatalytic properties. Although there are growing researches on TiO2 toxicity, studies examining the impact of TiO2 NPs physicochemical properties on their toxicity are limited. Therefore, the main aims of this thesis were: (i) to evaluate the toxicity of TiO2 NPs in human lung cells as a function of their main physicochemical properties, (ii) to evaluate if a short time exposure to UV light induced changes in the physicochemical properties of TiO2 NPs and eventually affected their toxicity.For these purposes, 4 custom made and one commercial TiO2 NPs which differ in size/SSA, shape, agglomeration, and surface functionalization/charge (APTES) were used. In the first stage of the study, the influence of the physicochemical properties of TiO2 NPs on their toxicity was evaluated on 3 different human lung cell systems (A549 epithelial cells, macrophages differentiated from THP-1, and A549/differentiated THP-1 cocultures). In general, TiO2 NPs caused a decrease in cell viability and induced a pro-inflammatory response depending on the cell type. The effect on toxicity was higher with larger sized, less agglomerated, rod-shaped, and positively charged nanoparticles. In the second stage of the study, we evaluated if a short time exposure of TiO2 NPs to UV light induced changes in their physicochemical properties and their toxicity. Irradiated TiO2 NPs induced a higher cytotoxic effect than the pristine TiO2 NPs in relation to an altered surface charge. After examining the toxicity of TiO2 NPs depending on their physicochemical and photocatalytic properties, protein corona composition, which is another factor affecting toxicity, was investigated. The parameters influencing the protein corona composition are mainly nanoparticle primary size and surface charge, no clear impact of the shape and agglomeration state was observed. No effect of UV irradiation was observed on the formation of the protein corona.Overall, the impact of the TiO2 NPs physicochemical properties on their toxicity was observed and the toxicity was more pronounced after UV irradiation of NPs. Besides another main finding of this study was that the co-culture model seemed more sensitive to the adverse effects of TiO2 NPs than the monoculture model.This study improves our understanding of the hazards and risks that five different types of pristine TiO2 NPs and their UV irradiated counterparts could pose to public health. It can serve as a basis for a safer by design approach to mitigate the toxicity of this material.Avec le développement rapide des nanosciences et des nanotechnologies, les préoccupations concernant les effets potentiels des nanoparticules sur la santé se sont renforcées. Les nanoparticules de dioxyde de titane (NPs de TiO2) sont largement utilisées dans une grande variété d'applications industrielles, principalement en raison de caractéristiques remarquables telles que leur taille, leur indice de réfraction ou leurs propriétés photocatalytiques. Bien que les recherches sur la toxicité du TiO2 soient de plus en plus nombreuses, les études examinant l'impact des propriétés physicochimiques des NPs de TiO2 sur leur toxicité sont limitées. Par conséquent, les principaux objectifs de cette thèse étaient d’évaluer : (i) la toxicité des NPs de TiO2 sur des cellules pulmonaires humaines en lien avec leurs principales propriétés physicochimiques, (ii) l’impact de l’exposition de courte durée des NPs de TiO2 à la lumière UV sur leurs propriétés physicochimiques et leur toxicité.Pour atteindre cet objectif, quatre types de NPs de TiO2 ont été synthétisés à façon et un TiO2 commercial a été utilisé. Ces cinq types de NPs de TiO2 diffèrent par leur taille/surface spécifique, leur forme, leur agglomération et leur fonctionnalisation/charge de surface (APTES). Dans la première étape de l'étude, l'effet des propriétés physicochimiques des NPs de TiO2 sur leur toxicité a été évalué sur 3 systèmes différents de cellules pulmonaires humaines (cellules épithéliales A549, macrophages différenciés à partir de THP-1, et cocultures de A549/THP-1 différenciées). En général, les NPs de TiO2 provoquent une diminution de la viabilité des cellules et induisent une réponse pro-inflammatoire selon le type de cellule. L'effet sur la toxicité était plus important avec des nanoparticules de plus grande taille primaire, moins agglomérées, en forme de bâtonnet et chargées positivement. Lors de la deuxième étape de l'étude, nous avons évalué si une exposition de courte durée des NPs de TiO2 aux rayons UV induisait des changements dans leurs propriétés physicochimiques et leur toxicité. Les NPs de TiO2 irradiées ont induit un effet cytotoxique plus élevé que les NPs de TiO2 non irradiées en lien avec une charge de surface modifiée. Après avoir examiné la toxicité des NPs de TiO2 en fonction de leurs propriétés physicochimiques et photocatalytiques, la formation de la corona protéique, qui est un autre facteur affectant la toxicité, a été étudiée. Les paramètres influençant la formation de la "protein corona" sont principalement la taille primaire des nanoparticules et la charge de surface, aucun impact clair de la forme et de l'état d'agglomération n'a été observé. Aucun effet de l'irradiation UV n'a été observé sur la formation de la couronne protéique.Dans l'ensemble, l'impact des propriétés physicochimiques des NPs de TiO2 sur leur toxicité a été observé et la toxicité est plus prononcée après l'irradiation UV des NPs. Une autre conclusion importante de cette étude est que le modèle de co-culture semble plus sensible aux effets indésirables des NPs de TiO2 que le modèle de monoculture.Cette étude contribue à améliorer notre compréhension des dangers et des risques que cinq types différents de NPs de TiO2 et leurs homologues irradiées aux UV peuvent présenter pour la santé publique. Elle peut servir de base à une approche "safer by design" pour atténuer la toxicité de ces nanoparticule

In vitro toxicity of titanium dioxide nanoparticles on human lung cells - impact of the physicochemical features

Avec le développement rapide des nanosciences et des nanotechnologies, les préoccupations concernant les effets potentiels des nanoparticules sur la santé se sont renforcées. Les nanoparticules de dioxyde de titane (NPs de TiO2) sont largement utilisées dans une grande variété d'applications industrielles, principalement en raison de caractéristiques remarquables telles que leur taille, leur indice de réfraction ou leurs propriétés photocatalytiques. Bien que les recherches sur la toxicité du TiO2 soient de plus en plus nombreuses, les études examinant l'impact des propriétés physicochimiques des NPs de TiO2 sur leur toxicité sont limitées. Par conséquent, les principaux objectifs de cette thèse étaient d’évaluer : (i) la toxicité des NPs de TiO2 sur des cellules pulmonaires humaines en lien avec leurs principales propriétés physicochimiques, (ii) l’impact de l’exposition de courte durée des NPs de TiO2 à la lumière UV sur leurs propriétés physicochimiques et leur toxicité.Pour atteindre cet objectif, quatre types de NPs de TiO2 ont été synthétisés à façon et un TiO2 commercial a été utilisé. Ces cinq types de NPs de TiO2 diffèrent par leur taille/surface spécifique, leur forme, leur agglomération et leur fonctionnalisation/charge de surface (APTES). Dans la première étape de l'étude, l'effet des propriétés physicochimiques des NPs de TiO2 sur leur toxicité a été évalué sur 3 systèmes différents de cellules pulmonaires humaines (cellules épithéliales A549, macrophages différenciés à partir de THP-1, et cocultures de A549/THP-1 différenciées). En général, les NPs de TiO2 provoquent une diminution de la viabilité des cellules et induisent une réponse pro-inflammatoire selon le type de cellule. L'effet sur la toxicité était plus important avec des nanoparticules de plus grande taille primaire, moins agglomérées, en forme de bâtonnet et chargées positivement. Lors de la deuxième étape de l'étude, nous avons évalué si une exposition de courte durée des NPs de TiO2 aux rayons UV induisait des changements dans leurs propriétés physicochimiques et leur toxicité. Les NPs de TiO2 irradiées ont induit un effet cytotoxique plus élevé que les NPs de TiO2 non irradiées en lien avec une charge de surface modifiée. Après avoir examiné la toxicité des NPs de TiO2 en fonction de leurs propriétés physicochimiques et photocatalytiques, la formation de la corona protéique, qui est un autre facteur affectant la toxicité, a été étudiée. Les paramètres influençant la formation de la "protein corona" sont principalement la taille primaire des nanoparticules et la charge de surface, aucun impact clair de la forme et de l'état d'agglomération n'a été observé. Aucun effet de l'irradiation UV n'a été observé sur la formation de la couronne protéique.Dans l'ensemble, l'impact des propriétés physicochimiques des NPs de TiO2 sur leur toxicité a été observé et la toxicité est plus prononcée après l'irradiation UV des NPs. Une autre conclusion importante de cette étude est que le modèle de co-culture semble plus sensible aux effets indésirables des NPs de TiO2 que le modèle de monoculture.Cette étude contribue à améliorer notre compréhension des dangers et des risques que cinq types différents de NPs de TiO2 et leurs homologues irradiées aux UV peuvent présenter pour la santé publique. Elle peut servir de base à une approche "safer by design" pour atténuer la toxicité de ces nanoparticulesWith the growing development of nanoscience and nanotechnology, concerns on the potential health effect of nanoparticles have increased. Titanium dioxide nanoparticles (TiO2 NPs) are widely used in a wide variety of industrial applications, mainly because of their unique properties such as their small size, high refractive index, or photocatalytic properties. Although there are growing researches on TiO2 toxicity, studies examining the impact of TiO2 NPs physicochemical properties on their toxicity are limited. Therefore, the main aims of this thesis were: (i) to evaluate the toxicity of TiO2 NPs in human lung cells as a function of their main physicochemical properties, (ii) to evaluate if a short time exposure to UV light induced changes in the physicochemical properties of TiO2 NPs and eventually affected their toxicity.For these purposes, 4 custom made and one commercial TiO2 NPs which differ in size/SSA, shape, agglomeration, and surface functionalization/charge (APTES) were used. In the first stage of the study, the influence of the physicochemical properties of TiO2 NPs on their toxicity was evaluated on 3 different human lung cell systems (A549 epithelial cells, macrophages differentiated from THP-1, and A549/differentiated THP-1 cocultures). In general, TiO2 NPs caused a decrease in cell viability and induced a pro-inflammatory response depending on the cell type. The effect on toxicity was higher with larger sized, less agglomerated, rod-shaped, and positively charged nanoparticles. In the second stage of the study, we evaluated if a short time exposure of TiO2 NPs to UV light induced changes in their physicochemical properties and their toxicity. Irradiated TiO2 NPs induced a higher cytotoxic effect than the pristine TiO2 NPs in relation to an altered surface charge. After examining the toxicity of TiO2 NPs depending on their physicochemical and photocatalytic properties, protein corona composition, which is another factor affecting toxicity, was investigated. The parameters influencing the protein corona composition are mainly nanoparticle primary size and surface charge, no clear impact of the shape and agglomeration state was observed. No effect of UV irradiation was observed on the formation of the protein corona.Overall, the impact of the TiO2 NPs physicochemical properties on their toxicity was observed and the toxicity was more pronounced after UV irradiation of NPs. Besides another main finding of this study was that the co-culture model seemed more sensitive to the adverse effects of TiO2 NPs than the monoculture model.This study improves our understanding of the hazards and risks that five different types of pristine TiO2 NPs and their UV irradiated counterparts could pose to public health. It can serve as a basis for a safer by design approach to mitigate the toxicity of this material

Putative adverse outcome pathways for silver nanoparticle toxicity on mammalian male reproductive system: a literature review

International audienceBackground Adverse outcome pathways (AOPs) are conceptual frameworks that organize knowledge about biological interactions and toxicity mechanisms. They present a sequence of events commencing with initial interaction(s) of a stressor, which defines the perturbation in a biological system (molecular initiating event, MIE), and a dependent series of key events (KEs), ending with an adverse outcome (AO). AOPs have recently become the subject of intense studies in a view to better understand the mechanisms of nanomaterial (NM) toxicity. Silver nanoparticles (Ag NPs) are one of the most explored nanostructures and are extensively used in various application. This, in turn, has increased the potential for interactions of Ag NPs with environments, and toxicity to human health. The aim of this study was to construct a putative AOPs (pAOP) related to reproductive toxicity of Ag NPs, in order to lay the groundwork for a better comprehension of mechanisms affecting both undesired toxicity (against human cell) and expected toxicity (against microorganisms).Methods PubMed and Scopus were systematically searched for peer-reviewed studies examining reproductive toxicity potential of Ag NPs. The quality of selected studies was assessed through ToxRTool. Eventually, forty-eight studies published between 2005 and 2022 were selected to identify the mechanisms of Ag NPs impact on reproductive function in human male. The biological endpoints, measurements, and results were extracted from these studies. Where possible, endpoints were assigned to a potential KE and an AO using expert judgment. Then, KEs were classified at each major level of biological organization.Results We identified the impairment of intracellular SH-containing biomolecules, which are major cellular antioxidants, as a putative MIE, with subsequent KEs defined as ROS accumulation, mitochondrial damage, DNA damage and lipid peroxidation, apoptosis, reduced production of reproductive hormones and reduced quality of sperm. These successive KEs may result in impaired male fertility (AO).Conclusion This research recapitulates and schematically represents complex literature data gathered from different biological levels and propose a pAOP related to the reproductive toxicity induced by AgNPs. The development of AOPs specific to NMs should be encouraged in order to provide new insights to gain a better understanding of NP toxicity

Putative adverse outcome pathways for silver nanoparticle toxicity on mammalian male reproductive system: a literature review

International audienceBackground Adverse outcome pathways (AOPs) are conceptual frameworks that organize knowledge about biological interactions and toxicity mechanisms. They present a sequence of events commencing with initial interaction(s) of a stressor, which defines the perturbation in a biological system (molecular initiating event, MIE), and a dependent series of key events (KEs), ending with an adverse outcome (AO). AOPs have recently become the subject of intense studies in a view to better understand the mechanisms of nanomaterial (NM) toxicity. Silver nanoparticles (Ag NPs) are one of the most explored nanostructures and are extensively used in various application. This, in turn, has increased the potential for interactions of Ag NPs with environments, and toxicity to human health. The aim of this study was to construct a putative AOPs (pAOP) related to reproductive toxicity of Ag NPs, in order to lay the groundwork for a better comprehension of mechanisms affecting both undesired toxicity (against human cell) and expected toxicity (against microorganisms).Methods PubMed and Scopus were systematically searched for peer-reviewed studies examining reproductive toxicity potential of Ag NPs. The quality of selected studies was assessed through ToxRTool. Eventually, forty-eight studies published between 2005 and 2022 were selected to identify the mechanisms of Ag NPs impact on reproductive function in human male. The biological endpoints, measurements, and results were extracted from these studies. Where possible, endpoints were assigned to a potential KE and an AO using expert judgment. Then, KEs were classified at each major level of biological organization.Results We identified the impairment of intracellular SH-containing biomolecules, which are major cellular antioxidants, as a putative MIE, with subsequent KEs defined as ROS accumulation, mitochondrial damage, DNA damage and lipid peroxidation, apoptosis, reduced production of reproductive hormones and reduced quality of sperm. These successive KEs may result in impaired male fertility (AO).Conclusion This research recapitulates and schematically represents complex literature data gathered from different biological levels and propose a pAOP related to the reproductive toxicity induced by AgNPs. The development of AOPs specific to NMs should be encouraged in order to provide new insights to gain a better understanding of NP toxicity

Influence of the physicochemical features of TiO 2 nanoparticles on the formation of a protein corona and impact on cytotoxicity

International audienceDue to their unique properties TiO2 nanoparticles are widely used. The adverse effects they may elicit are usually studied in relation to their physicochemical features. However, a factor is often neglected: the influence of the protein corona formed around nanoparticles upon contact with biological media. Indeed, although it is acknowledged that it can strongly influence nanoparticle toxicity, it is not systematically considered. The aim of this study was to characterize the formation of the protein corona of TiO2 nanoparticles as a function of the main nanoparticle properties and investigate potential relationship with the cytotoxicity nanoparticles induce in vitro in human lung cells. To that purpose, five TiO2 nanoparticles differing in size, shape, agglomeration state and surface charge were incubated in cell culture media (DMEM or RPMI supplemented with 10% fetal bovine serum) and the amount and profile of adsorbed proteins on each type of nanoparticle were compared to their toxicological profile. While nanoparticle size and surface charge were found to be determinant factors for protein corona formation, no clear impact of the shape and agglomeration state was observed. Furthermore, no clear relationship was evidenced between the protein corona of the nanoparticles and the adverse effect they elicited

Evaluation of skin irritation potentials of different cosmetic products in Turkish market by reconstructed human epidermis model.

Human skin is a protective barrier against the toxic effects of cosmetics. Marketing of cosmetic products with ingredients tested on animals was prohibited in 2013. Since then, safety evaluation of cosmetic products is performed by using alternative in vitro toxicity tests. In vitro 3-D reconstructed human epidermis (RhE) tissue models are now used to define skin irritation/corrosion potentials of cosmetic ingredients and end-products. The main aim of this study was to evaluate skin irritation potentials of topically used cosmetic end-products which were marketed in Turkey during 2015-2017, by using the EpiDerm in vitro 3D-human skin model. Sixty widely used cosmetic products were collected from different markets/cosmetic shops. Among hair care products, only one shampoo was found to be strong/severe skin irritant/possible corrosive while 22 shampoos were moderate skin irritant and 11 shampoos were moderate to mild skin irritant. Among 6 skin care products, one was found to be moderate to mild skin irritant. We can suggest that alternative in vitro tests should continuously be used to test both the ingredients and the final cosmetic formulations

New 1,2,3-triazoles and their oxime derivatives: AChE/BChE enzyme inhibitory and DNA binding properties

1,2,3-Triazole compounds (1a–3a) and their oxime derivatives (1b–3b) were synthesized. The structures of these synthesized compounds were characterized using common spectroscopic methods. Crystal structures of the compounds 3, 2b and 3b were determined by single crystal X-ray diffraction studies. The acetylcholinesteras (AChE) and butyrylcholinesterase (BChE) cholinesterase inhibitor (ChEI) and DNA/calf serum albumin (BSA) binding properties of the compounds were examined. DNA binding studies have shown that compounds interact with DNA through 1,2,3-triazole and oxime groups. When the binding constant Kb values were compared, it was revealed that compound 3b (Kb = 4.6 × 105 M−1) with oxime in its structure binds more strongly than the others. In addition, in vitro BSA binding studies showed that compounds 1b and 3b exhibited higher binding affinity. These results confirm that the quenching is due to the formation of a compound resulting from the static quenching mechanism, rather than being initiated by a dynamic mechanism. Likewise, when the enzyme activity of the compounds was examined, the compounds exhibited high inhibitory activity against AChE. The highest activity was observed for compounds 2b and 3b (8.6 ± 0.05 and 4.8 ± 0.052 µM). It was observed that the compounds were not selective with respect to BChE. Communicated by Ramaswamy H. Sarma</p

Collagen scaffolds with in situ-grown calcium phosphate for osteogenic differentiation of Wharton's jelly and menstrual blood stem cells

The aim of this research was to investigate the osteogenic differentiation potential of non-invasively obtained human stem cells on collagen nanocomposite scaffolds with in situ-grown calcium phosphate crystals. The foams had 70% porosity and pore sizes varying in the range 50-200 mu m. The elastic modulus and compressive strength of the calcium phosphate containing collagen scaffolds were determined to be 234.5 kPa and 127.1 kPa, respectively, prior to in vitro studies. Mesenchymal stem cells (MSCs) obtained from Wharton's jelly and menstrual blood were seeded on the collagen scaffolds and proliferation and osteogenic differentiation capacities of these cells from two different sources were compared. The cells on the composite scaffold showed the highest alkaline phosphatase activity compared to the controls, cells on tissue culture polystyrene and cells on collagen scaffolds without in situ-formed calcium phosphate. MSCs isolated from both Wharton's jelly and menstrual blood showed a significant level of osteogenic activity, but those from Wharton's jelly performed better. In this study it was shown that collagen nanocomposite scaffolds seeded with cells obtained non-invasively from human tissues could represent a potential construct to be used in bone tissue engineering. Copyright (C) 2012 John Wiley & Sons, Ltd

Evaluation of skin irritation potentials of different cosmetic products in Turkish market by reconstructed human epidermis model

Human skin is a protective barrier against the toxic effects of cosmetics. Marketing of cosmetic products with ingredients tested on animals was prohibited in 2013. Since then, safety evaluation of cosmetic products is performed by using alternative in vitro toxicity tests. In vitro 3-D reconstructed human epidermis (RhE) tissue models are now used to define skin irritation/corrosion potentials of cosmetic ingredients and end-products. The main aim of this study was to evaluate skin irritation potentials of topically used cosmetic end-products which were marketed in Turkey during 2015-2017, by using the EpiDerm in vitro 3D-human skin model. Sixty widely used cosmetic products were collected from different markets/cosmetic shops. Among hair care products, only one shampoo was found to be strong/severe skin irritant/possible corrosive while 22 shampoos were moderate skin irritant and 11 shampoos were moderate to mild skin irritant. Among 6 skin care products, one was found to be moderate to mild skin irritant. We can suggest that alternative in vitro tests should continuously be used to test both the ingredients and the final cosmetic formulations