The retinal pigment epithelium (RPE), which ensures the normal functioning of the neural retina, is a pigmented single-cell layer that separates the retina from the Bruch’s membrane and the choroid. There are three main types of pigment granules in the RPE cells of the human eye: lipofuscin granules (LG) containing the fluorescent “age pigment” lipofuscin, melanoprotein granules (melanosomes, melanolysosomes) containing the screening pigment melanin and complex melanolipofuscin granules (MLG) containing both types of pigments simultaneously—melanin and lipofuscin. This review examines the functional role of pigment granules in the aging process and in the development of oxidative stress and associated pathologies in RPE cells. The focus is on the process of light-induced oxidative degradation of pigment granules caused by reactive oxygen species. The reasons leading to increased oxidative stress in RPE cells as a result of the oxidative degradation of pigment granules are considered. A mechanism is proposed to explain the phenomenon of age-related decline in melanin content in RPE cells. The essence of the mechanism is that when the lipofuscin part of the melanolipofuscin granule is exposed to light, reactive oxygen species are formed, which destroy the melanin part. As more melanolipofuscin granules are formed with age and the development of degenerative diseases, the melanin in pigmented epithelial cells ultimately disappears.

Purpose:The retinal pigment epithelium (RPE) is a monolayer of epithelial cells essential for photoreceptor function and viability. Quail Coturnix japonica is a convenient experimental animal model for the study of age and pathological retina processes to an accelerated time regime. The three main types of pigment granules present in the RPE are melanin-containing melanosomes, lipofuscin-containing lipofuscin granules, and mixed melanolipofuscin granules containing both melanin and lipofuscin. The purpose of this work was to study the process of melanolipofuscinogenesis during aging and under light exposure. Methods:We examined melanolipofuscin granules in "macular" areas, the area of the retina containing oxycarotenoids, as a function of the macula in humans, of the quail retina by transmission electron microscopy in young, middle-aged, and old birds, and in middle-aged birds irradiated with blue LED light (450 nm, 4 J/cm2). Results:It has been shown that during photo-oxidative stress caused by the action of blue light on the quail eye, active fusion of melanosomes and lipofuscin granules occurs with formation of various types, including giant, mixed melanolipofuscin-like granules. Increased accumulation of melanolipofuscin-like granules was also observed in non-irradiated old birds. Conclusions:It is assumed that the decrease in the number of melanosomes in the RPE during aging and photo-oxidative stress is associated with their fusion with lipofuscin granules and subsequent degradation of melanin by reactive oxygen species formed in melanolipofuscin-like granules. The disappearance of melanin deprives the RPE cells of light-filtering and antioxidant protection, and significantly increases the risk of their oxidative stress.

It has previously been shown that heteroaromatic antioxidant oxibiol (N-acetylcysteinate 6-hydroxy-2-aminobenzothiazole) inhibits the process of fructosylation of serum albumin. The aim of this study is to elucidate the inhibitory effect of oxibiol on modification of proteins by photodegradation products of bisretinoid A2E, the main fluorophore of lipofuscin granules in retinal pigment epithelial cells of the human eye. It was shown that unlike a water-soluble fraction fraction from non-irradiated A2E-liposomes, a water-soluble fraction formed after irradiation of A2E-liposomes with visible light significantly modified albumin in a day after incubation at 37°C. Oxibiol in millimolar concentrations effectively inhibited this process. The inhibitory effect of oxybiol could be attributed to its antioxidant activity and the ability to compete with reactive aldehydes formed during the photooxidative degradation of A2E-cardiolipin liposomes. The acute toxicity of oxibiol in mice after intraperitoneal injection was studied, the values of LD 10 and LD 50 were determined. The results obtained demonstrate that oxibiol can be used in pharmacology for preventing and curing diseases associated with the development of oxidative stress in various fields of medicine, primarily in ophthalmology.

An aqueous extract from the larvae of black beetles Ulomoides dermestoides grown under controlled conditions was obtained and its proteomic analysis was performed based on one-dimensional electrophoretic separation of proteins, their trypsinolysis in a gel, and subsequent chromatography-mass spectrometry. Protein identification was performed using MaxQuant v.1.6.3.4 software. The Uniprot database was used to identify proteins by homology. Catalase activity was determined spectrophotometrically by a hydrogen peroxide concentration decrease. Antioxidant activity was evaluated by luminol chemiluminescence quenching. The extract contained proteins that can determine the biological activity of the extract: universal regulators of cellular processes calmodulin (6.2%), cytochrome c-2 (13.5%), nucleoside diphosphate kinase (11.1%), the enzymatic antioxidants superoxide dismutase, catalase, glutathione S-transferase, peroxiredoxin, and glutathione synthetase as well as thioredoxin, 70 kDa and 60 kDa heat shock proteins, and a chitinase complex (13.4% in total). The catalase activity was 45.9 ± 6.5 µmol H2O2/min/mg protein; the antioxidant activity of 1 mg protein per ml extract was equivalent to 2.1 ± 0.3 mM trolox. The prospects for the practical use of the extract as a natural antioxidant complex were noted.

An aqueous extract from the larvae of black beetles Ulomoides dermestoides grown under controlled conditions was obtained and its proteomic analysis based on one-dimensional electrophoretic separation of proteins, their trypsinolysis in a gel and subsequent chromatography-mass spectrometry was performed. Protein identification was performed using MaxQuant v.1.6.3.4 software. The Uniprot database was used to identify proteins by homology. Catalase activity was determined spectrophotometrically by hydrogen peroxide concentration decrease. Antioxidant activity was evaluated by luminol chemiluminescence quenching. The extract contained proteins that can determine the biological activity of the extract: universal regulators of cellular processes calmodulin (62%), cytochrome c-2 (13.5%), nucleoside diphosphate kinase (11.1%), the enzymatic antioxidants superoxide dismutase, catalase, glutathione S-transferase, peroxiredoxin, glutathione synthetase as well as thioredoxin, 70 and 60 kDa heat shock proteins, chitinase complex (13.4% in total). Catalase activity was 6.3 ± 1.1 µmol H2O2/min/mg protein; antioxidant activity of 1 mg protein per ml extract was equivalent to 1.36 ± 0.3 mM trolox. The prospects for practical use of the extract as a natural antioxidant complex were noted.

It is known that during the process of aging, there is a significant decrease in the number of melanosomes in the retinal pigment epithelium (RPE) cells in the human eye. Melanosomes act as screening pigments in RPE cells and are fundamentally important for protection against the free radicals generated by light. A loss or change in the quality of melanin in melanosomes can lead to the development of senile pathologies and aggravation in the development of various retinal diseases. We have previously shown that the interaction between melanin melanosomes and superoxide radicals results in oxidative degradation with the formation of water-soluble fluorescent products. In the present study, we show, using fluorescence analysis, HPLC, and mass spectrometry, that visible light irradiation on melanolipofuscin granules isolated from RPE cells in the human eye results in the formation of water-soluble fluorescent products from oxidative degradation of melanin, which was in contrast to lipofuscin granules and melanosomes irradiation. The formation of these products occurs as a result of the oxidative degradation of melanin by superoxide radicals, which are generated by the lipofuscin part of the melanolipofuscin granule. We identified these products both in the composition of melanolipofuscin granules irradiated with visible light and in the composition of melanosomes that were not irradiated but were, instead, oxidized by superoxide radicals. In the melanolipofuscin granules irradiated by visible light, ions that could be associated with melanin oxidative degradation products were identified by applying the principal component analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data. Degradation of the intact melanosomes by visible light is also possible; however, this requires significantly higher irradiation intensities than for melanolipofuscin granules. It is concluded that the decrease in the concentration of melanin in RPE cells in the human eye with age is due to its oxidative degradation by reactive oxygen species generated by lipofuscin, as part of the melanolipofuscin granules, under the action of light.

The field of radiation countermeasures is growing, however, currently there are no effective and non-toxic compounds which could be administered orally to the individuals post exposure to high doses of ionising radiation. The pigment melanin is ubiquitous through all kingdoms of life and provides selective advantage under radiation stress through its role as a chemical and physical shield, and its capacity to respond and react to exposures. Soluble allomelanin was administered to mice following whole-body exposure to lethal or sublethal doses of gamma radiation to determine its capacity to mitigate the effects of acute radiation syndrome, and its utility as a radiation countermeasure. Allomelanin has shown a trend to improve survival post an 8 Gy sublethal radiation exposure when administered up to 48 h post-irradiation. Furthermore, it improved median and overall survival to a 10 Gy lethal radiation exposure, specifically when administered at 24 h post-irradiation. Histological analysis on the jejunum region of the small intestine of this treatment group indicated that alterations of the mucosal and submucosal architecture, and disruption of the lymphatic system associated with lethal radiation exposure were mitigated when allomelanin was administered at 24 h post-irradiation. Based on this work soluble allomelanin derived from a fungal source could serve as an easily sourced, cost-effective, and viable countermeasure to accidental radiation exposure and merits further investigation.

Lipofuscin granules from retinal pigment epithelium (RPE) cells contain bisretinoid fluorophores, which are photosensitizers and are phototoxic to cells. In the presence of oxygen, bisretinoids are oxidized to form various products, containing aldehydes and ketones, which are also potentially cytotoxic. In a prior study, we identified that bisretinoid oxidation and degradation products have both hydrophilic and amphiphilic properties, allowing their diffusion through the lipofuscin granule membrane into the RPE cell cytoplasm, and are thiobarbituric acid (TBA)-active. The purpose of the present study was to determine if these products exhibit a toxic effect to the RPE cell also in the absence of light. The experiments were performed using the lipofuscin-fed ARPE-19 cell culture. The RPE cell viability analysis was performed with the use of flow cytofluorimetry and laser scanning confocal microscopy. The results obtained indicated that the cell viability of the lipofuscin-fed ARPE-19 sample was clearly reduced not immediately after visible light irradiation for 18 h, but after 4 days maintaining in the dark. Consequently, we could conclude that bisretinoid oxidation products have a damaging effect on the RPE cell in the dark and can be considered as an aggravating factor in age-related macular degeneration progression.

Lipofuscin granules (LGs) are accumulated in the retinal pigment epithelium (RPE) cells. The progressive LG accumulation can somehow lead to pathology and accelerate the aging process. The review examines composition, spectral properties and photoactivity of LGs isolated from the human cadaver eyes. By use of atomic force microscopy and near-field microscopy, we have revealed the fluorescent heterogeneity of LGs. We have discovered the generation of reactive oxygen species by LGs, and found that LGs and melanolipofuscin granules are capable of photoinduced oxidation of lipids. It was shown that A2E, as the main fluorophore (bisretinoid) of LGs, is much less active as an oxidation photosensitizer than other fluorophores (bisretinoids) of LGs. Photooxidized products of bisretinoids pose a much greater danger to the cell than non-oxidized one. Our studies of the fluorescent properties of LGs and their fluorophores (bisretinoids) showed for the first time that their spectral characteristics change (shift to the short-wavelength region) in pathology and after exposure to ionizing radiation. By recording the fluorescence spectra and fluorescence decay kinetics of oxidized products of LG fluorophores, it is possible to improve the methods of early diagnosis of degenerative diseases. Lipofuscin (“aging pigment”) is not an inert “slag”. The photoactivity of LGs can pose a significant danger to the RPE cells. Fluorescence characteristics of LGs are a tool to detect early stages of degeneration in the retina and RPE.

Age-related macular degeneration (AMD) is the primary cause of central blindness among the elderly. AMD is associated with progressive accumulation of lipofuscin granules in retinal pigment epithelium (RPE) cells. Lipofuscin contains bisretinoid fluorophores, which are photosensitizers and are phototoxic to RPE and neuroretinal cells. In the presence of oxygen, bisretinoids are also oxidized, forming various products, consisting primarily of aldehydes and ketones, which are also potentially cytotoxic. In a prior study, we identified that in AMD, bisretinoid oxidation products are increased in RPE lipofuscin granules. The purpose of the present study was to determine if these products were toxic to cellular structures. The physicochemical characteristics of bisretinoid oxidation products in lipofuscin, which were obtained from healthy donor eyes, were studied. Raman spectroscopy and time-of-flight secondary ion mass spectrometry (ToF–SIMS) analysis identified the presence of free-state aldehydes and ketones within the lipofuscin granules. Together, fluorescence spectroscopy, high-performance liquid chromatography, and mass spectrometry revealed that bisretinoid oxidation products have both hydrophilic and amphiphilic properties, allowing their diffusion through lipofuscin granule membrane into the RPE cell cytoplasm. These products contain cytotoxic carbonyls, which can modify cellular proteins and lipids. Therefore, bisretinoid oxidation products are a likely aggravating factor in the pathogenesis of AMD.

Aging of the retina is accompanied by a sharp increase in the content of lipofuscin granules and bisretinoid A2E in the cells of the retinal pigment epithelium (RPE) of the human eye. It is known that A2E can have a toxic effect on RPE cells. However, the specific mechanisms of the toxic effect of A2E are poorly understood. We investigated the effect of the products of photooxidative destruction of A2E on the modification of bovine serum albumin (BSA) and hemoglobin from bovine erythrocytes. A2E was irradiated with a blue light-emitting diode (LED) source (450 nm) or full visible light (400–700 nm) of a halogen lamp, and the resulting water-soluble products of photooxidative destruction were investigated for the content of carbonyl compounds by mass spectrometry and reaction with thiobarbituric acid. It has been shown that water-soluble products formed during A2E photooxidation and containing carbonyl compounds cause modification of serum albumin and hemoglobin, measured by an increase in fluorescence intensity at 440–455 nm. The antiglycation agent aminoguanidine inhibited the process of modification of proteins. It is assumed that water-soluble carbonyl products formed as a result of A2E photodestruction led to the formation of modified proteins, activation of the inflammation process, and, as a consequence, to the progression of various senile eye pathologies.

Extracts of larvae and beetle Ulomoides dermestoides with high antioxidant activity were obtained: 1 mg/ml of larval extract protein is equivalent in antioxidant activity to 1.36 mM Trolox. The extract contains peptides of thioredoxin and glutathione redox systems, superoxide dismutase, catalase, heat shock proteins 70 kDa. Animals that received 400 micrograms/kg of extract for 1 month with food showed better cognitive abilities than the control ones.

В настоящее время в результате аварий при добыче, транспортировке и другим причинам происходит загрязнение окружающей среды и промышленных объектов различными вредными химическими веществами, в том числе нефтепродуктами. Поэтому для защиты природы от загрязнения, по-прежнему актуальна проблема разработки новых сорбционных материалов для локализации и сбора загрязнений, особенно эффективных для очистки водных сред. Новый подход решения этой экологической проблемы состоит в применении магнитоуправляемых сорбентов, а также, сорбентов на основе опилок, лигнина, лузги и т.д., обладающие большой сырьевой базой. В работе представлены результаты разработки технологии получения модифицированных углеродных дисперсных сорбционных материалов кластерами металлов и изготовления сорбционных конструкций для сбора и очистки водной поверхности от нефтяных загрязнений. Приводятся характеристики дисперсных углеродсодержащих сорбентов, полученных из отходов лесотехнических производств. Currently, as a result of accidents during production, transportation and other reasons, the environment and industrial facilities are polluted with various harmful chemicals, including oil products. Therefore, to protect nature from pollution, the problem of developing new sorption materials for the localization and collection of pollution, especially effective for the purification of aqueous media, is still urgent. A new approach to solving this environmental problem consists in the use of magnetically controlled sorbents, as well as sorbents based on sawdust, lignin, husk, etc., which have a large raw material base. The paper presents the results of the development of a technology for obtaining modified carbon dispersed sorption materials by metal clusters and the manufacture of sorption structures for collecting and cleaning the water surface from oil pollution. The characteristics of dispersed carbon-containing sorbents obtained from wastes of forestry industries are given.

A biologically active extract from the darkling beetle Ulomoides dermestoides was obtained using the electro-pulse plasma dynamic extraction method. The beetle water extract contained a complex of antioxidant substances such as antioxidant enzymes and nonprotein antioxidants, as well as a complex of heat shock antistress proteins. This determines the rather high antioxidant activity of the aqueous extract of the beetle, i.e., 1 mg of dry matter/mL of the extract has an equivalent antioxidant activity to 0.2 mM Trolox (a water-soluble analog of vitamin E). It was shown that the beetle extract can lead to a 25–30% increase in the average lifespan of nematode Caenorhabditiselegans, under normal conditions, and a 12–17% increase under conditions of oxidative stress (with paraquat), and significantly inhibits the fructosylation reaction of serum albumin. Therefore, the beetle aqueous extract shows promise as a biologically active complex exhibiting antioxidant activity.

Ommochromes are screening and antioxidant pigments in the compound eyes of invertebrates and fulfil the functions of light filtration, light absorption, and antioxidant defense. We report here the first observation that ommochromes display antiglycation activity in vitro. Ommochromes were prepared from the eyes of insects of three different families: Strationyidae , Sphingidae , and Acrididae . All the ommochromes studied were found to inhibit the reaction forming fluorescent serum albumin modification products in the presence of high fructose concentrations (fructosylation). Ommochromes from the eyes of the black soldier fly ( Hermetia illucens ) were the most effective fructosylation inhibitors. Ommochromes oxidized with hydrogen peroxide produced no inhibitory action in relation to glycation. Our results are of interest both for understanding the biological role of ommochromes in invertebrates, in particular for clarifying their influence on oxidative modification of the proteins of the retinular and pigment cells of ommatidia, and for using them to create pharmacological agents for the treatment and prevention of pathology associated with the development of metabolic syndrome.

An aqueous extract was obtained from the biomass of Hermetia illucens larvae using the electro-pulse plasma-dynamic method. The extract was highly effective in quenching the chemiluminescence of luminol in the presence of hemoglobin and hydrogen peroxide. It contained the dark pigment melanin with a concentration of paramagnetic centers of 8.3 × 10 16 spin/g of dry matter and antioxidant activity. The antiradical properties of the extract were confirmed on the model of oxidative stress of the nematode Caenorhabditis elegans in the presence of 40 mmol of paraquat: the introduction of the extract increased the median lifespan of the nematode by 25%. The antioxidant effect identified is associated with the presence of a complex of antioxidants in the extract and, possibly, antioxidant enzymes that destroy hydroperoxides.