Photoinduced Toxicity Research Articles

Photolysis of p-phenylenediamine rubber antioxidants in aqueous environment: Kinetics, pathways and their photo-induced toxicity

The widespread use of rubber antioxidants, especially p-phenylenediamines (PPDs), has raised increasing concerns about their risk assessment. However, there is a notable lack of research on their transformation products (TPs). Photolysis, influenced by active components, plays a significant role in the environmental fates of PPDs. This study investigated four emerging PPDs (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), N, N′-diphenyl-p-phenylenediamine (DPPD), N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD), and N-cyclohexyl-N′-phenyl-p-phenylenediamine (CPPD)) through a combination of experiments (photolysis kinetics, quenching experiments, acute toxicity test to Vibrio Fischeri (V. fischeri) and identification of photolytic products) and theoretical calculations. The results revealed different pathways for indirect photolysis mediated by the hydroxyl radicals (•OH) and singlet oxygen (1O2) of DPPD and IPPD under simulated sunlight irradiation. The effects of dissolved organic matter (DOM) and fulvic acid (FA) on the rates of photolysis of PPDs highlighted the complex interactions among the molecular structure, light absorption properties, and environmental variables. Quenching for reactive oxygen species (ROS) reduced photo-induced toxicity, whereas the addition of DOM and FA increased it, suggesting the crucial role of ROS in the formation of more toxic photolytic products. The study of photolysis pathways and the evaluation of the health risks provide a comprehensive understanding of the environmental effects of these pollutants.

Exploring the aqueous photodegradation of three ionisable macrolide antibiotics: Kinetics, intermediates and photoinduced toxicity

Three macrolide antibiotics (MLs, i.e., roxithromycin, clarithromycin and spiramycin) were investigated to reveal the aqueous photochemistry of the respective neutral and dissociated species (i.e., H2MLs+, HMLs0 and MLs−), including their susceptibility to direct photolysis as well as the hydroxyl radical (•OH) and singlet oxygen (1O2) mediated photooxidation. Under simulated sunlight (λ > 290 nm), no obvious or slow photodegradation of the three MLs were observed in pure water, while they photodegraded rapidly under shorter wavelength irradiation (λ > 200 nm). It was further found that the dependence of the kinetics on pH was attributed to the different reactivities of the dissociation species. The rate constants and cumulative light absorption increased with the order H2MLs+ < HMLs0 < MLs−. Based on competition kinetic experiments and matrix calculations, MLs− was differentiated to be more highly reactive towards •OH/1O2. The corresponding environmental half-lives were evaluated considering the reactivities and proportions of the speciated forms at different pH, indicating that 1O2 oxidation (t1O2,E = 1.83–2.53 h) contributed more than •OH oxidation (t•OH,E = 33.17–787.49 h) to the ML phototransformation in sunlit surface waters. In general, these reactions preserved the core backbone structures of the parent ML molecules and gave rise to intermediates that displayed higher toxicity to Vibrio fischeri than the parent molecules, hence demonstrating photo-modified toxicity. These results are of importance towards the goal of assessing the persistence of MLs during wastewater treatment using UV-light tertiary treatment processes, as well as in sunlit surface waters.

Photochemical behaviour and toxicity evolution of phenylbenzoate liquid crystal monomers in water

Liquid crystal monomers (LCMs) are a group of emerging pollutants that pose potential environmental risks because of their ubiquitous occurrence and toxicity. Understanding their environmental transformation is essential for assessing the ecological risk. In this study, we investigated the photochemical transformation kinetics, mechanism, and photo-induced toxicity of three phenylbenzoate LCMs in water. Their apparent photolytic rate constants were within (0.023 – 0.058) min-1, and the half-lives were < 30.0 min, showing lower persistence in water. Dissolved organic matter significantly inhibited their photolysis because of light-shielding effect and quenching of excited triplet states of LCMs. Their photolysis mainly occurred through excited triplet states, and the reactive oxygen species (i.e., ⋅OH, 1O2 and ⋅O2-) contributed to their degradation. The main photolysis pathways were ester bond cleavage, ⋅OH substitution/addition, and defluorination. Experiments and computational simulation revealed that some ·OH addition/substitution products have similar toxicity with LCMs. Additionally, the ∙OH reaction rate constants (kOH) of LCMs were determined to be > 1 × 109 M-1 s-1, evidence for their high reactivity toward ⋅OH. We have further developed reliable methods to estimate kOH of other phenylbenzoate-like LCMs with quantum chemical calculations. These results are useful for understanding the transformation and fate of LCMs in aquatic environments.

The Assessment of Photo-Induced Toxicity of [NaYF4:Yb3+, Er3+] Upconversion Nanoparticles on Model Normal and Cancer Cell Lines in Vitro

The Assessment of Photo-Induced Toxicity of [NaYF4:Yb3+, Er3+] Upconversion Nanoparticles on Model Normal and Cancer Cell Lines in Vitro

Photosensitizing effects and physicochemical properties of chlorophyll a derivatives with hydrophilic oligoethylene glycol fragments at the macrocycle periphery.

In this work, screening studies of the cytotoxic effect of chlorins with fragments of di-, tri-, and pentaethylene glycol at the macrocycle periphery in relation to HeLa, A549, and HT29 cells were performed. It is shown that, despite different hydrophobicity, all the compounds studied have a comparable photodynamic effect. The conjugate of chlorin e6 with pentaethylene glycol, which has the lowest tendency to association among the studied compounds with tropism for low density lipoproteins and the best characteristics of the formation of molecular complexes with Tween 80, has a significant difference in dark and photoinduced toxicity (ratio IC50(dark)/IC50(photo) approximately 2 orders of magnitude for all cell lines), which allows to hope for a sufficiently large "therapeutic window". A study of the interaction of this compound with HeLa cells shows that the substance penetrates the cell and, after red light irradiation induces ROS appearance inside the cell, associated, apparently, with the photogeneration of singlet oxygen. These data indicate that photoinduced toxic effects are caused by damage to intracellular structures as a result of oxidative stress. Programmed type of cell death characterized with caspase-3 induction is prevailing. So, the conjugate of chlorin e6 with pentaethylene glycol is a promising antitumor PS that can be successfully solubilized with Tween 80, which makes it suitable for further in vivo studies.

Photoinduced Toxicity Caused by Gold Nanozymes and Photodynamic Dye Encapsulated in Submicron Polymer Shell

AbstractThe development of nanozymes, artificial enzymes made from inorganic nanoparticles, is widely studied due to their affordability, durability, and strength. Gold nanoparticles (AuNPs) are employed to imitate peroxidase, glucose oxidase, lactate oxidase, superoxide dismutase, and catalase. The last one transforms intracellular hydrogen peroxide into molecular oxygen, whose deficiency is characteristic of the hypoxic tumor microenvironment. Thus, gold nanoparticles are thought to enhance the overall effectiveness of photodynamic therapy. However, the enzyme‐like activity of nanoparticles rapidly decreases in biological media, due to the aggregation and formation of the so‐called “protein corona”. In this study, polymeric submicrocapsules loaded with AuNPs and a photodynamic dye are fabricated via Layer‐by‐Layer (LbL) assembly. The enhancement of photodynamic treatment efficacy by in situ production of oxygen by the catalase‐like effect of AuNPs is investigated. Polymeric capsules are thoroughly characterized in terms of physicochemical and catalytic properties, and as a proof of concept, their therapeutic potential is evaluated in vitro. Furthermore, encapsulated AuNPs shows significantly lower aggregation both upon storage and during the reaction course. The results shows that the polymer capsules, containing AuNPs and photodynamic dye, show significantly higher light‐induced cytotoxicity in comparison to the individual photodynamic dye, suggesting a synergistic effect between the formation of molecular oxygen by catalase‐like gold nanozymes and photodynamic action.

Obtaining emulsions of furanocoumarins from Sosnowsky’s hogweed and &lt;i&gt;in vitro&lt;/i&gt; assessment of their phototoxic effect

Background. Furanocoumarin-based drugs are used for photochemotherapy of various diseases. Sosnovsky’s hogweed can be an available source of furanocoumarins for the development of drugs.The aim of the study. To obtain stable emulsions containing furanocoumarins from Sosnowski’s hogweed and to evaluate their photocytotoxicity.Materials and methods. To obtain the emulsions, furanocoumarins were extracted with chloroform from the sap of the aerial part of the Sosnowski’s hogweed. The chloroform extract was clarified by silica gel gradient column chromatography. The extractive fraction containing furanocoumarins was analyzed by high performance liquid chromatography with ultraviolet (UV) detection. An extract with a high content of 8-methoxypsoralen was used to prepare two types of emulsions. The extract was dissolved in peach oil and emulsified in water with tween-80 (emulsion No. 1) and in an aqueous glycerin solution with lecithin (emulsion No. 2).The emulsions were tested for dark and photo-induced toxicity for human lung fibroblasts. The dose of UV radiation for the photoactivation of furanocoumarins was 9 J/cm2. A solution of chlorine e6 was used as a comparison photosensitizer.Results. The obtained emulsions contained 1 mg/ml 8-methoxypsoralen. Both emulsions were homogeneous at macro- and microscopic visualization, remained stable when stored under various temperature conditions for 14 days. Emulsion No. 2 did not show dark toxicity and caused a statistically significant inhibition of cell viability under UV irradiation at a concentration of 12.5–31.3 µg/mL. Emulsion No. 1 had a toxic effect on cells regardless of UV irradiation due to the content of tween-80. According to fluorescent microscopy, the phototoxic effect of emulsion No. 2 was manifested mainly due to apoptosis, in contrast to the effect of chlorine e6, in which there were more pronounced signs of cell necrosis.Conclusion. The developed experimental emulsions of furanocoumarins from Sosnovski’s hogweed are an example of promising medicinal photosensitizers of plant origin for phototherapy of various dermatological and oncological diseases.

Synthesis, dark and photoinduced cytotoxicity of a deuteroporphyrin IX derivative with two galactose fragments on the macrocycle periphery

A deuteroporphyrin IX derivative with two D-galactose fragments with an ester bond between macrocycle and carbohydrate fragments was synthesized. The synthesis was done by esterifying both ester groups of deuteroporphyrin IX with diacetone-D-galactose using 2-chloro-1-methylpyridinium iodide (Mukayama reagent) followed by the removal of the isopropylidene protection of carbohydrate fragments by the action of aqueous trifluoroacetic acid to form the target derivative. The study of dark toxicity of the deuteroporphyrin IX derivative synthesized against HeLa cells allows us to conclude that galactose fragment introduction resulted in the cytotoxicity decrease as compared with the parent deuteroporphyrin IX but photoinduced cytotoxicity of the deuteroporphyrin IX derivative with two D-galactose fragments had increased in contrast to the deuteroporphyrin IX. It has been shown that oxidative stress due to ROS induction causes the photoinduced toxicity of the porphyrins studied.

Photochemical behavior and photo-induced toxicity of chiral pesticides and their chiral monomers in aqueous environment

The photochemical behaviors of chiral pollutants in aqueous solutions are rarely studied using chiral monomers, which may hamper their precise risk assessment and lead to suspicious conclusions. In this study, we systematically investigated the phototransformation behavior and toxicity evolution of two widely used chiral pesticides (triadimefon (TF) and triadimenol (TN)) at enantiomer and diastereomer levels, and proposed a calculation method of total photolysis rate constants of chiral mixture. Results show that TF and TN could be photodegraded faster in pure water than in natural waters, and the observed photolysis rate constants (kobs) of TN with two chiral centers exhibit enantioselectivity, i.e., kobs(TN-RS) = kobs(TN-SR) > kobs(TN-RR) = kobs(TN-SS). The photolysis of TF and TN mainly occurs through their excited singlet and triplet states, respectively. Their photodegradation pathways mainly include dechlorination and elimination of triazole ring. TF could also undergo ether bond cleavage. It is also found that, both TF and TN exhibit photo-induced toxicity to V. fischeri, due to the generation of more toxic products than parent compounds. Furthermore, TN exhibits enantioselective photo-induced toxicity after 240-min irradiation, which could be ascribed to the formation of chiral products. These results could benefit the understanding of enantioselective environmental behavior of chiral pollutants.

Conjugates of Tetrapyrrolic Macrocycles as Potential Anticancer Target-Oriented Photosensitizers

Photodynamic therapy is a minimally invasive treatment of tumors using photosensitizers, light, and reactive oxygen species, which can destroy cellular structures. With the development of photodynamic therapy, significant efforts have been made to create new efficient photosensitizers with improved delivery to cells, stability, and selectivity against cancer tissues. Naturally occurring tetrapyrrolic macrocycles, such as porphyrins and chlorins, are very attractive as photosensitizers, and their structural modification and conjugation with other biologically active molecules are promising approaches for creating new photosensitizers specifically targeting cancer cells. The present review aims to highlight recent developments in the design, preparation, and investigation of complex conjugates of tetrapyrrolic macrocycles, which can potentially be used as sensitizers for target-oriented photodynamic therapy of cancer. In this review, we discuss the structure, photodynamic effect, and anticancer activity of the following conjugates of tetrapyrrolic macrocycles: (1) conjugates obtained by modifying peripheral substituents in porphyrins and chlorins; (2) conjugates of porphyrins and chlorins with lipids, carbohydrates, steroids, and peptides; (3) conjugates of porphyrins and chlorins with anticancer drugs and some other biologically active molecules; (4) metal-containing conjugates. The question of how the conjugate structure affects its specificity, internalization, localization, and photoinduced toxicity within cancer cells is the focus of this review.

Recommendations for advancing test protocols examining the photo-induced toxicity of petroleum and polycyclic aromatic compounds

Photo-induced toxicity of petroleum products and polycyclic aromatic compounds (PACs) is the enhanced toxicity caused by their interaction with ultraviolet radiation and occurs by two distinct mechanisms: photosensitization and photomodification. Laboratory approaches for designing, conducting, and reporting of photo-induced toxicity studies are reviewed and recommended to enhance the original Chemical Response to Oil Spills: Ecological Research Forum (CROSERF) protocols which did not address photo-induced toxicity. Guidance is provided on conducting photo-induced toxicity tests, including test species, endpoints, experimental design and dosing, light sources, irradiance measurement, chemical characterization, and data reporting. Because of distinct mechanisms, aspects of photosensitization (change in compound energy state) and photomodification (change in compound structure) are addressed separately, and practical applications in laboratory and field studies and advances in predictive modeling are discussed. One goal for developing standardized testing protocols is to support lab-to-field extrapolations, which in the case of petroleum substances often requires a modeling framework to account for differential physicochemical properties of the constituents. Recommendations are provided to promote greater standardization of laboratory studies on photo-induced toxicity, thus facilitating comparisons across studies and generating data needed to improve models used in oil spill science.

A State-of-the-Art Review on the Alternatives to Animal Testing for the Safety Assessment of Cosmetics

Almost a decade after the stipulated deadline in the 7th amendment to the EU Cosmetics Directive, which bans the marketing of animal-tested cosmetics in the EU from 2013, animal experimentation for cosmetic-related purposes remains a topic of animated debate. Cosmetic industry continues to be scrutinised for the practice, despite its leading role in funding and adopting innovation in this field. This paper aims to provide a state-of-the-art review of the field on alternative testing methods, also known as New Approach Methodologies (NAMs), with the focus on assessing the safety of cosmetic ingredients and products. It starts with innovation drivers and global regulatory responses, followed by an extensive, endpoint-specific overview of accepted/prospective NAMs. The overview covers main developments in acute toxicity, skin corrosion/irritation, serious eye damage/irritation, skin sensitisation, repeated dose toxicity, reproductive toxicity/endocrine disruption, mutagenicity/genotoxicity, carcinogenicity, photo-induced toxicity, and toxicokinetics. Specific attention was paid to the emerging in silico methodology. This paper also provides a brief overview of the studies on public perception of animal testing in cosmetics. It concludes with a view that educating consumers and inviting them to take part in advocacy could be an effective tool to achieve policy changes, regulatory acceptance, and investment in innovation.

Microwave-assisted synthesis and photodynamic activity of tris-heteroleptic Ru(II) complexes with asymmetric polypyridyl ligands

Ru(II) polypyridyl complexes are attracting particular attention as possible photodynamic therapy (PDT) agents due to their interesting photophysical properties, which can be easily tunable through the appropriate selection of attached ligands. However, blue-wavelength absorption of the complexes limited their potential application. In this study, three tris-heteroleptic Ru(II) polypyridyl complexes were synthesized to shift the absorption of the compounds toward longer wavelengths. Their photophysical, biological, and photodynamic properties were evaluated. The mechanism of the photoinduced toxicity was investigated by fluorescence and electron paramagnetic resonance (EPR) techniques in vitro and in aqueous solutions. The results revealed the photodynamic activity of the studied compounds is based mainly on the photogeneration of 1O2 and H2O2. Additionally, the synthesized Ru complexes demonstrated high activity in inhibiting the detachment of cancer cells. This effect was additionally enhanced by light activation of Ru compounds. The presented findings demonstrate a rational strategy for the efficient synthesis of tris-heteroleptic Ru(II) polypyridyl complexes to be used as promising photodynamic agents for cancer and antimetastatic treatments.

Transcriptomic responses and apoptosis in larval red drum (Sciaenops ocellatus) co-exposed to crude oil and ultraviolet (UV) radiation

Ultraviolet (UV) radiation can significantly increase the toxicity of polycyclic aromatic hydrocarbons (PAHs) in crude oil to early life stage (ELS) fishes through photo-induced /photo-enhanced toxicity. However, little is known about the sub-lethal effects and mechanisms of photo-induced PAH toxicity in ELS fishes. The present study investigated apoptosis and global transcriptomic effects in larval red drum (Sciaenops ocellatus) (24–72 h post-fertilization) following co-exposure to oil (0.29–0.30 μg/L ∑PAH50) and UV. Apoptosis was quantified using the TUNEL assay, and transcriptomic effects were assessed using RNA sequencing analysis. Apoptotic fluorescence was greatest in the eyes and skin following 24 and 48 h co-exposure to oil and UV, indicating photo-induced toxicity. Consistent with these phenotypic responses, pathways associated with phototransduction, eye development, and dermatological disease were among the top predicted pathways impacted. The present study is the first to provide global transcriptomic analysis of UV and oil co-exposure in an ELS fish.

Modeling and mechanistic understanding of cytotoxicity of metal oxide nanoparticles (MeOxNPs) to Escherichia coli: categorization and data gap filling for untested metal oxides

Metal oxide nanoparticles (MeOxNPs) production is expected to increase every year exponentially, and their potential to cause adverse effect to the environment and human health will also expand rapidly. Hence, risk assessment of nanoparticles (NPs) is necessary to design ecosafe products. However, experimental ecotoxicological assessments are time-consuming requiring a lot of resources. Therefore, researchers rely on alternative in silico approaches to predict the behavior of NPs in the biological system. Quantitative structure − toxicity relationship (QSTR) has been adopted as a potential method to predict the cytotoxicity of untested NPs. Hence, in the present study, multiple linear regression (MLR) models were developed using 17 MeOxNPs on Escherichia coli (E. coli) bacteria cells under both light and dark conditions. The models were developed applying Small Dataset Modeler software, version 1.0.0 (http://teqip.jdvu.ac.in/QSAR_Tools/DTCLab/) which generates models with a limited number of data points. Periodic table-based descriptors (both 1st and 2nd generation) were used for the modeling purpose. Two statistically significant MLR models based on photo-induced toxicity ( R 2 = 0.726) and dark-based toxicity ( R 2 = 0.770) were developed. From the developed models, we interpreted that increase in valency and oxidation state of the metal will decrease the cytotoxicity whereas the atomic radius of the metal and electronegativity of MeOxNPs influence the toxicity toward E. coli cells. The MLR models were validated using different internal validation metrics. Additionally, we have collected 42 MeOxNPs as an external set to observe the predictive power of the two developed MLR models and categorize them into toxic and non-toxic classes. The chemical features selected in the developed models are important for understanding the mechanisms of nanotoxicity. Thus, the developed models can be a scientific basis for designing safer NPs.

A review of alternative methods to the use of animals in safety evaluation of cosmetics

ABSTRACTAlternative methods to the use of animals in research have been a global trend, mainly after the publication of the 3R’s principle (Replacement, Reduction, and Refinement), proposed by Russel and Burch. In the cosmetic sector, safety and efficacy assessments using animals have generated controversial debates. For this reason, in vitro research techniques are widely used to assess acute toxicity; corrosivity and irritation; skin sensitization; dermal and percutaneous absorption; repeated dose toxicity; reproductive toxicity; mutagenicity and genotoxicity; carcinogenicity; toxicokinetic studies; photo-induced toxicity; and human data. Although there are many methodologies described, validated, and widely used in the cosmetic area, the evaluation of the safety of cosmetic ingredients and products is still an expanding field. It needs global collaboration among regulatory agencies, universities, and industry, to meet several unmet needs in the fields of sensitization, carcinogenicity, systemic action, among other issues involving safety of users of cosmetic products. This review article will cover the currently most relevant in vitro models regarding irritation, corrosion, sensitization, mutagenicity, genotoxicity, and phototoxicity, to help to choose the most appropriate test for evaluating the safety and toxicity of cosmetic ingredients and products.

Mechanisms of photoinduced toxicity of AgNPs to the microalgae Chlorella pyrenoidosa in the presence of hematite nanoparticles: insights from transcriptomics, metabolomics and the photochemical index

AgNPs attachment to HemNPs have caused photoinduced cytotoxicity, elevating the AgNPs toxicity to C. pyrenoidosa by producing free radicals and improving photocatalytic activity under illumination.

Influence of polystyrene microplastics on the volatilization, photodegradation and photoinduced toxicity of anthracene and pyrene in freshwater and artificial seawater

In this study, the influences of polystyrene microplastics (PS MPs) on the volatilization, photodegradation and photoinduced toxicities of anthracene and pyrene were determined in freshwater and artificial seawater. The PS MPs reduced the volatilization of anthracene and pyrene, and the volatilization reduction was highly dependent on the PS MPs sizes and concentrations. The PS MPs increased the photodegradation kinetics (kp) of anthracene by promoting 1O2 generation and altered the photodegradation pathways through OH attack of the photodegradation byproducts. However, the kp of pyrene was decreased by PS MPs suppressing the transfer of electrons from excited pyrene to oxygen. The PS MPs modified the pathways of pyrene photodegradation via OH attack of the photodegradation byproducts. Due to light shielding by DOM and/or PS MPs aggregates in seawater, the modification of the photodegradation pathways of anthracene and pyrene by PS MPs was hardly happened in seawater compared with in freshwater. By changing the concentrations of anthracene or pyrene and their photodegradation byproducts, the PS MPs greatly affected the photoinduced toxicities of anthracene and pyrene to Selenastrum capricornutum and Phaeodactylum tricornutum. The influences of PS MPs on the volatilization, photodegradation and photoinduced toxicity of anthracene and pyrene are important and should be carefully considered during environmental risk assessments of anthracene and pyrene.

Comparative analysis on the photolysis kinetics of four neonicotinoid pesticides and their photo-induced toxicity to Vibrio Fischeri: Pathway and toxic mechanism

Neonicotinoids are widely used pesticides all over the world and pose severe water pollution. Although they can be degraded via absorbing sunlight, few attentions have been paid to the environmental risks of their photolysis products. In this paper, the photo-toxicity was investigated for four neonicotinoids (dinotefuran, nitenpyram, thiamethoxam and clothianidin) based on a series of experiments (i.e., photolysis kinetics, radical scavenging, bioluminescent inhibition test to Vibrio Fischeri and intermediate identification) and in-silico calculation of photolysis pathway. The results show that direct photolysis dominates the photolysis of the four neonicotinoids under simulated sunlight radiation. The bioluminescent inhibition kinetics shows that all four neonicotinoids have photo-induced toxicity to V. fischeri, but with different light-induced responses. Scavenging radicals (·OH and 1O2) will decrease the photo-induced toxicity of all the four neonicotinoids, indicating radicals play important roles to the photo-chemical reactions of intermediates. Dissolved organic matters exhibit slightly shading effect to the photolysis rates of four parent compounds. However, the ROSs generated by DOM can accelerate the photo-chemical reactions of intermediates, leading to different photo-induced toxicity in present of DOM. According to the detected intermediates and Gaussian calculations, there are different photolysis pathways and mechanisms for the four neonicotinoids. The calculation for photo-sensitization reactions with 3O2 indicates that both energy transfer reactions and electron transfer reactions can be produced under simulated sunlight radiation, which further consolidate that reactive oxygen species are involved in the photolysis process. A theoretical model has been developed to explain the toxicity variations of four neonicotinoids in different aqueous conditions.

Uptake of microalgae as sublethal biomarker reveals phototoxicity of oxytetracycline to the crustacean Daphnia magna

Antibiotics are considered emerging pollutants as their presence in the environment is increasingly common. Although their environmental concentrations are generally low, they can pose risk to organisms through bioaccumulation, causing sublethal effects. Furthermore, solar radiation can trigger reactions in certain compounds after their accumulation within organisms or in the environment. Toxicity and photoinduced toxicity of oxytetracycline (OTC, widely used antibiotic in salmon aquaculture) on Daphnia magna (Crustacea, Cladocera) and microalgae Raphidocelis subcapitata (Chlorophyceae) as its food source was assessed via aqueous exposure. Also, the impact via diet (microalga) to the crustacean was examined. In addition to lethal (immobility) effect, in vivo chlorophyll fluorescence techniques were used to determine food ingestion (gut content as a biomarker of physiological health) in D. magna and physiological status of microalgae. OTC (≤10 mg L − 1) was not acutely (24 h) toxic to R. subcapitata when measured as maximum quantum yield (Fv/Fm) in darkness. However, under short (1 h) UV exposure OTC caused irreversible decrease of Fv/Fm (50%) at ≥0.5 mg L − 1. OTC was not acutely lethal to D. magna (≤10 mg L − 1), however, sublethal effects (43% decrease in food ingestion) at 10 mg L − 1 were demonstrated. UV exposure (4.5 h) strongly exacerbated toxicity of OTC, leading to lethal (87% immobility) and sublethal (81% decrease of feeding in survived individuals) effects. Uptake of OTC (aqueous exposure) and its photosensitization in tissues of D. magna under UV exposure was confirmed. On the other hand, rapid bioadsorption of OTC on cell surface was evident in R. subcapitata. Uptake of OTC in D. magna through diet could not be confirmed at short-term. Photomodification of OTC under UV exposure was observed through changes in its absorption spectrum. The results show that short exposure to summer UV levels of southern Chile can rapidly induce phototoxicity of OTC, suggesting a potential risk to aquatic organisms.