Light-induced Lipid Peroxidation Research Articles

Cyanidin-3-glucoside protects the photooxidative damage of retinal pigment epithelium cells by regulating sphingolipid signaling and inhibiting MAPK pathway

Cyanidin-3-glucoside (C3G) is the most common anthocyanin in dark grains and berries and is a food functional factor to improve visual health. However, the mechanisms of C3G on blue light-induced retinal pigment epithelial (RPE) cell photooxidative damage needs further exploration. We investigated the effects of C3G on blue light-irradiated A2E-containing RPE cells and explored whether sphingolipid, mitogen-activated protein kinase (MAPK), and mitochondria-mediated pathways are involved in this mechanism. Blue light irradiation led to mitochondria and lysosome damage in RPE cells, whereas C3G preserved mitochondrial morphology and function and maintained the lysosomal integrity. C3G suppressed the phosphorylation of JNK and p38 MAPK and mitochondria-mediated pathways to inhibit RPE cell apoptosis. Lipidomics data showed that C3G protected RPE cells against blue light-induced lipid peroxidation and apoptosis by maintaining sphingolipids balance. C3G significantly inhibited ceramide (Cer d18:0/15:0, Cer d18:0/16:0 and Cer d18:0/18:0) accumulation and elevated galactosylceramide (GalCer d18:1/15:0 and GalCer d18:1/16:0) levels in the irradiated A2E-containing RPE cells. Furthermore, C3G attenuated cell membrane damage by increasing phosphatidylcholine and phosphatidylserine levels. C3G inhibited apoptosis and preserved the structure of mitochondria and lysosome by regulating sphingolipid signaling and suppression of MAPK activation in RPE cells. Thus, dietary supplementation of C3G prevents retinal photooxidative damage.

Reducing Pseudomonas fluorescens in milk through photodynamic inactivation using riboflavin and curcumin with 450 nm blue light-emitting diode

This study determined the phototoxic potential of riboflavin (RIB) and curcumin (CUR) against Pseudomonas fluorescens (P. fluorescens) in vitro and in fluid milk using factorial arrangements. Photodamage was investigated by transmission electron microscopy. The milk was illuminated by thin layers or constant agitation to verify its efficiency in practical industrial situations, as well as to monitor changes in food quality. High loads of P. fluorescens were photoinactivated through cell membrane disruption with extravasation of intracellular content. CUR was more efficient than RIB. The milky matrix hinders the absorption of light by photosensitising molecules (PSs), but there was still a reduction in the number of bacteria. The different lighting methods were not significant. The macronutrient composition and protein oxidation levels were not altered. Light induced lipid peroxidation. PSs changed the milk's colour. Therefore, photodynamic inactivation (PDI) is an alternative to reduce contaminating microorganisms in food while preserving quality.

A Model Eumelanin from 5,6-Dihydroxyindole-2-Carboxybutanamide Combining Remarkable Antioxidant and Photoprotective Properties with a Favourable Solubility Profile for Dermo-Cosmetic Applications

The search for new synthetic melanin-related pigments that maintain the antioxidant and photoprotective properties of naturally occurring dark eumelanins, while overcoming their unfavorable solubility, and molecular heterogeneity is presently a very active issue for dermo-cosmetic purposes. In this work, we explored the potential of a melanin obtained from the carboxybutanamide of a major eumelanin biosynthetic precursor, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), by aerobic oxidation under slightly alkaline conditions. Analysis of the pigment by EPR, ATR-FTIR and MALDI MS indicated a substantial structural similarity to DHICA melanin, while investigation of the early intermediates confirmed unchanged regiochemistry of the oxidative coupling. The pigment exhibited a UVA-visible absorption even more intense than that of DHICA melanin, and a noticeable solubility in polar solvents of dermo-cosmetic relevance. The hydrogen- and/or electron-donor ability, and the iron (III) reducing power as determined by conventional assays provided evidence for marked antioxidant properties not merely ascribable to the more favorable solubility profile, while the inhibitory action of the radical- or photosensitized solar light-induced lipid peroxidation was more marked compared to that of DHICA melanin. Overall, these results hint at this melanin, which remarkable properties are, in part, due to the electronic effects of the carboxyamide functionality as a promising functional ingredient for dermo-cosmetic formulations.

Сравнительное исследование оксидантных свойств окисленных и неокисленных бисретиноидов липофусциновых гранул ретинального пигментного эпителия глаза человека

Актуальность. Недавно нами было показано, что при возрастной макулярной дегенерации сетчатки наблюдается повышенное содержание продуктов фотоокисления и фотодеградации бисретиноидов по сравнению с нормой. Поэтому на сегодняшний день вопрос о фототоксичности этих продуктов становится актуальным для решения проблемы поиска путей лечения и профилактики патологии. Цель. Провести сравнительное исследование фотосенсибилизирующего действия N-ретинилиден-N-ретинилэтаноламина (А2Е) и продуктов его фотоокисления и фотодеградации на индуцированную видимым светом пероксидацию липидов фоторецепторных мембран. Материалы и методы. При помощи метода высокоэффективной жидкостной хроматографии были получены отдельные фракции неокисленных и окисленных бисретиноидов в хлороформном экстракте липофусциновых гранул из ретинального пигментного эпителия кадаверных глаз. Результаты. Проведено сравнительное исследование фототоксических свойств неокисленных и окисленных бисретиноидов липофусциновых гранул из клеток ретинального пигментного эпителия глаза человека на пероксидацию липидов наружных сегментов фоторецепторных клеток. Выводы. Окисленные бисретиноиды липофусциновых гранул менее фототоксичны по сравнению с их неокисленными формами. Background. Recently we have shown that age-related macular degeneration is associated with higher than normal levels of bisretinoid photo-oxidation and photo-degradation products. Therefore, the issue of their phototoxicity currently becomes relevant for finding ways to treat and prevent this pathology. Aim. To conduct a comparative study of the photosensitizing effect of N-retinylidene-N-retinylethanolamine (A2E) and its photooxidation and photodegradation products on light-induced lipid peroxidation in photoreceptor membranes. Materials and methods. Using high-performance liquid chromatography fractions of unoxidized and oxidized bisretinoids were isolated in the chloroform extract of lipofuscin granules from the retinal pigment epithelium of cadaver eyes. Results. The study compared phototoxic effects of unoxidized and oxidized bisretinoids of lipofuscin granules from human retinal pigment epithelial cells on lipid peroxidation in rod outer segments. Conclusions. Oxidized bisretinoids of lipofuscin granules are less phototoxic compared to their unoxidized forms.

Blue light induces a neuroprotective gene expression program in Drosophila photoreceptors

BackgroundLight exposure induces oxidative stress, which contributes to ocular diseases of aging. Blue light provides a model for light-induced oxidative stress, lipid peroxidation and retinal degeneration in Drosophila melanogaster. In contrast to mature adults, which undergo retinal degeneration when exposed to prolonged blue light, newly-eclosed flies are resistant to blue light-induced retinal degeneration. Here, we sought to characterize the gene expression programs induced by blue light in flies of different ages to identify neuroprotective pathways utilized by photoreceptors to cope with light-induced oxidative stress.ResultsTo identify gene expression changes induced by blue light exposure, we profiled the nuclear transcriptome of Drosophila photoreceptors from one- and six-day-old flies exposed to blue light and compared these with dark controls. Flies were exposed to 3 h blue light, which increases levels of reactive oxygen species but does not cause retinal degeneration. We identified substantial gene expression changes in response to blue light only in six-day-old flies. In six-day-old flies, blue light induced a neuroprotective gene expression program that included upregulation of stress response pathways and downregulation of genes involved in light response, calcium influx and ion transport. An intact phototransduction pathway and calcium influx were required for upregulation, but not downregulation, of genes in response to blue light, suggesting that distinct pathways mediate the blue light-associated transcriptional response.ConclusionOur data demonstrate that under phototoxic conditions, Drosophila photoreceptors upregulate stress response pathways and simultaneously, downregulate expression of phototransduction components, ion transporters, and calcium channels. Together, this gene expression program both counteracts the calcium influx resulting from prolonged light exposure, and ameliorates the oxidative stress resulting from this calcium influx. Thus, six-day-old flies can withstand up to 3 h blue light exposure without undergoing retinal degeneration. Developmental transitions during the first week of adult Drosophila life lead to an altered gene expression program in photoreceptors that includes reduced expression of genes that maintain redox and calcium homeostasis, reducing the capacity of six-day-old flies to cope with longer periods (8 h) of light exposure. Together, these data provide insight into the neuroprotective gene regulatory mechanisms that enable photoreceptors to withstand light-induced oxidative stress.

Cytochrome b5 protects photoreceptors from light stress-induced lipid peroxidation and retinal degeneration

Lipid peroxides are generated by oxidative stress in cells, and contribute to ageing and neurodegenerative disease. The eye is at special risk for lipid peroxidation because photoreceptors possess amplified sensory membranes rich in peroxidation-susceptible polyunsaturated fatty acids. Light-induced lipid peroxidation in the retina contributes to retinal degeneration, and lipid peroxidation has been implicated in the progression of age-associated ocular diseases such as age-related macular degeneration (AMD). Here, we show that exposing Drosophila melanogaster to strong blue light induces oxidative stress including lipid peroxidation that results in retinal degeneration. Surprisingly, very young flies are resilient to this acute light stress, suggesting they possess endogenous neuroprotective mechanisms. While lipophilic antioxidants partially suppressed blue light-induced retinal degeneration in older flies, we find that overexpression of cytochrome b5 (Cyt-b5) completely suppressed both blue light-induced lipid peroxidation and retinal degeneration. Our data identify Cyt-b5 as a neuroprotective factor that targets light-induced oxidative damage, particularly lipid peroxidation. Cyt-b5 may function via supporting antioxidant recycling, thereby providing a strategy to prevent oxidative stress in ageing photoreceptors that would be synergistic with dietary antioxidant supplementation.

WO3/Pt nanoparticles promote light-induced lipid peroxidation and lysosomal instability within tumor cells

Although metal–metal oxide nanoparticles have attracted considerable interest as catalysts, they have attracted little interest in nanomedicine. This is likely due to the fact that metal oxide semiconductors generally require biologically harmful ultraviolet excitation. In contrast, this study focuses upon WO3/Pt nanoparticles, which can be excited by visible light. To optimize the nanoparticles’ catalytic performance, platinization was performed at alkaline pH. These nanoparticles destroyed organic dyes, consumed dissolved oxygen and produced hydroxyl radicals. 4T1 breast cancer cells internalized WO3/Pt nanoparticles within the membrane-bound endo-lysosomal compartment as shown by electron and fluorescence microscopy. During visible light exposure, but not in darkness, WO3/Pt nanoparticles manufacture reactive oxygen species, promote lipid peroxidation, and trigger lysosomal membrane disruption. As cells of the immune system degrade organic molecules, produce reactive oxygen species, and activate the lipid peroxidation pathway within target cells, these nanoparticles mimic the chemical attributes of immune effector cells. These biomimetic nanoparticles should become useful in managing certain cancers, especially ocular cancer.

Visible Light-Induced Lipid Peroxidation of Unsaturated Fatty Acids in the Retina and the Inhibitory Effects of Blueberry Polyphenols

The lipid peroxidation of unsaturated fatty acids (UFAs) in the retina not only threatens visual cells but also affects the physiological health of the retina. In this work, the potential damages caused by daily visible light exposure on retinal UFAs were evaluated via a simulated in vitro model. At the same time, the benefits of dietary supplementation of blueberries to the eyes were also assessed. After prolonged light exposure, lipid peroxidation occurred for both docosahexaenoic and arachidonic acids (DHA and AA, respectively). The oxidized UFAs presented obvious cytotoxicity and significantly inhibited cell growth in retinal pigment epithelium cells. Among the different blueberry polyphenol fractions, the flavonoid-rich fraction, in which quercetin was discovered as the main component, was considerably better in preventing visible light-induced DHA lipid peroxidation than the anthocyanin- and phenolic acid-rich fractions. Then the retinal protective activity of blueberry polyphenols against light-induced retinal injury was confirmed in vivo. On the basis of the above results, inhibiting lipid peroxidation of UFAs in the retina is proposed to be another important function mechanism for antioxidants to nourish eyes.

Structure-dependent lipid peroxidation by photoirradiation of pyrene and its mono-substituted derivatives

Pyrene, one of the most studied polycyclic aromatic hydrocarbons, can damage biological macromolecules and cause toxicity when irradiated by light. The effect of substituents, 1-amino, 1-hydroxy, 1-nitro, and 1-bromo, on light-induced lipid peroxidation is studied. Degradation kinetics and photoproduct analyses were conducted to test how these substituents affect the photoreaction. All five compounds have widely different photodegradation rates, with degradation half-lives, ranging from 8 min to 495 min. These rates parallel their light absorptivity. Four out of the five compounds induce lipid peroxidation when irradiated with UVA light, whereas 1-aminopyrene causes minimum or no lipid peroxidation. The relative amount of lipid peroxidation caused is: 1-bromopyrene > pyrene > 1-nitropyrene ≈ 1-hydroxypyrene > 1-aminopyrene. This relative lipid peroxidation is dependent on the substituent due to the following factors: light absorptivity, relative rates of the competing processes in the excited states, nature of the photoreaction, and nature of the photoproducts.

Retinol dehydrogenase 12 detoxifies 4-hydroxynonenal in photoreceptor cells

Mutations of the photoreceptor retinol dehydrogenase 12 ( RDH12) gene cause the early onset retinal dystrophy Leber congenital amaurosis (LCA) by mechanisms not completely resolved. Determining the physiological role of RDH12 in photoreceptors is the focus of this study. Previous studies showed that RDH12, and the closely related retinol dehydrogenase RDH11, can enzymatically reduce toxic lipid peroxidation products such as 4-hydroxynonenal (4-HNE), in vitro. To explore the significance of this activity, we investigated the ability of RDH11 and RDH12 to protect stably transfected HEK-293 cells against the toxicity of 4-HNE. Both enzymes protected against 4-HNE modification of proteins and 4-HNE-induced apoptosis in HEK-293 cells. In the retina, exposure to bright light induced lipid peroxidation, 4-HNE production, and 4-HNE modification of proteins in photoreceptor inner segments, where RDH11 and RDH12 are located. In mouse retina, RDH12—but not RDH11—protected against adduct formation, suggesting that 4-HNE is a physiological substrate of RDH12. RDH12—but not RDH11—also protected against light-induced apoptosis of photoreceptors. We conclude that in mouse retina RDH12 reduces 4-HNE to a nontoxic alcohol, protecting cellular macromolecules against oxidative modification and protecting photoreceptors from light-induced apoptosis. This activity is of particular significance to the understanding of the molecular mechanisms of RDH12-induced LCA.

UVA photoirradiation of anhydroretinol – formation of singlet oxygen and superoxide

Anhydroretinol is a metabolite of vitamin A (retinol) and a major photodecomposition product of retinyl palmitate and retinyl acetate. Anhydroretinol is biologically active, inducing cell death in lymphoblastoid cells, prevention of N-methyl-N-nitrosourea-induced mammary cancer, and inhibition of cell growth in lymphocytes. We have previously determined that photoirradiation of anhydroretinol in the presence of a lipid, methyl linoleate, with UVA light-induced lipid peroxidation. In the present study, electron spin resonance (ESR) spin-trap techniques were employed to explore the mechanism of lipid peroxidation initiation. Irradiation of anhydroretinol by UVA in the presence of 2,2,6,6-tetramethylpiperidine (TEMP), a specific probe for singlet oxygen, resulted in the formation of TEMPO, indicating that singlet oxygen was generated. During photoirradiation in the presence of 5,5-dimethyl N-oxide pyrroline (DMPO), a specific probe for superoxide, ESR signals for DMPO-OOH were formed, and these signals were quenched by superoxide dismutase. The involvement of singlet oxygen on the induction of lipid peroxidation was also evidenced by the observation that lipid peroxidation was inhibited by sodium azide and enhanced by deuterium oxide. Our overall results provide evidence that photoirradiation of anhydroretinol with UVA light generates reactive oxygen species, e.g. singlet oxygen and superoxide, which mediate the induction of lipid peroxidation.

Synthesis and photoirradiation of isomeric ethylchrysenes by UVA light leading to lipid peroxidation.

Polycyclic aromatic hydrocarbons (PAHs) are widespread genotoxic environmental pollutants. We have recently demonstrated that photoirradiation of PAHs leads to cytotoxicity, DNA damage, and induction of lipid peroxidation. In this paper we report the synthesis of all the six isomeric ethylchrysenes and the study of light-induced lipid peroxidation by these ethylchrysenes. 5-Ethylchrysene was synthesized by reaction of 5-keto-5,6,6a,7,8,9,10,10a-octahydrochrysene with CH3CH2MgBr followed by dehydration catalyzed by p-toluenesulfonic acid and dehydrogenation with DDQ in benzene. 1- and 4-Ethylchrysenes were similarly prepared by reaction of 1-keto-1,2,3,4,5,6-hexahydrochrysene and 4-keto-1,2,3,4-tetrahydrochrysenes, respectively with CH3CH2MgBr followed by dehydration and dehydrogenation. Direct acetylation of chrysene followed by Wolff-Kishner or Clemmensen reduction resulted in the formation of 2-, 3-, and 6-ethylchrysenes in 4%, 16%, and 43% yields, respectively. Photoirradiation of these compounds with 7 and 21 J/cm2 UVA light in the presence of methyl linoleate all resulted in lipid peroxidation. For comparison, photoirradiation of 4-methylchrysene and 5-methylchrysene was similarly conducted. For irradiation at a UVA light dose of 21 J/cm2, the level of induced lipid peroxidation is in the order 4-methylchrysene = 5-methylchrysene = 5-ethylchrysene = 4-ethylchrysene = chrysene > 1-ethylchrysene = 2-ethylchrysene > 3-ethylchrysene > 6-ethylchrysene. Compared with chrysene, these results indicate that the ethyl group at C4 or C5 position either slightly enhances or has no effect on the light-induced lipid peroxidation, while at C1-, C2-, C3-, or C6 position reduces light-induced lipid peroxidation.

Carboxymethylated (1 –> 3)-β-D-Glucan Protects Liposomes Against Ultraviolet Light-Induced Lipid Peroxidation

In this study we have analyzed antioxidant capabilities of the carboxymethylated (1 --> 3)-beta-D-glucan (M(w) = 5.88 x 10(5)) against lipid peroxidation induced by ultraviolet (UV) radiation--UVA (320-400 nm), which is known to produce mainly singlet oxygen, (1)O(2) . Lipid peroxidation was monitored by measuring the absorption spectra of the conjugated dienes and quantified by Klein oxidation index. The results imply that the (1 --> 3)-beta-D-glucan derivative studied is an antioxidant with the scavenging ability lying between alpha-tocopherol and hyaluronic acid. Thus, glucan as a potential safe and effective dietary supplement may be used for a prolonged time for a systemic photoprotection of humans.

On-line monitoring of UV-induced lipid peroxidation products from human skin in vivo using proton-transfer reaction mass spectrometry

Proton-transfer reaction mass spectrometry (PTR-MS) was used to study ultraviolet (UV) light-induced lipid peroxidation in human skin, in vivo. Emissions of volatile organic compounds (VOCs) in the mass range between 20 and 150 amu in the headspace of the skin of 16 healthy volunteers were monitored before, during and after irradiation in an on-line and non-invasive fashion. From these experiments, five volatile substances were found to reflect the damage caused by UV-radiation. The two major compounds (monitored at mass 45 and 59 amu) were identified as acetaldehyde and propanal using a combination of Tenax-based gas chromatographic pre-separation with PTR-MS. The other volatiles (with characteristic ions at, among others, masses 73 and 87 amu) could not be identified. Simultaneous measurement of the established lipid peroxidation biomarker ethene using laser-based photoacoustic trace gas detection revealed a similar pattern and statistically significant correlations between VOC production measured with PTR-MS and ethene. Variations in UV-radiation intensity were reflected by the amount of acetaldehyde and propanal emitted from the skin. Our results show that acetaldehyde and propanal can be used as biomarkers for lipid peroxidation.

In the presence of ferritin, visible light induces lipid peroxidation of the porcine photoreceptor outer segment

We studied the synergistic effect of visible light and ferritin on the lipid peroxidation on a fraction of porcine photoreceptor outer segment (POS). Reaction mixtures containing the POS fraction and horse spleen ferritin were irradiated under white fluorescent light mainly at 17,000 lx or incubated under dark conditions at 37°C. The lipid peroxidation was evaluated by both the thiobarbituric acid method and the ferrous oxidation/xylenol orange method. The irradiation-induced lipid peroxidation was affected by some experimental factors such as the irradiation dose and acidity of the material. When the irradiation was stopped, the lipid peroxidation was also stopped; thereafter, the re-irradiation induced lipid peroxidation. Moreover, this lipid peroxidation was inhibited by desferrioxamine, an iron chelator, or by dimethylthiourea, a hydroxyl radical scavenger, suggesting that the lipid peroxidation involves hydroxyl radicals generated via the Fenton reaction by iron ion released from ferritin. The lipid peroxidation did not take place under dark conditions or in the absence of ferritin. This study suggested the possibility that the visible light-induced lipid peroxidation of the POS fraction in the presence of ferritin may participate in the etiology of human retinal degenerative diseases as the human retina is exposed to light for life.

Protective Effect of Egg Yolk Phosvitin Against Ultraviolet- Light-Induced Lipid Peroxidation in the Presence of Iron Ions

It is known that nonheme iron accumulates and free radicals are generated in skin exposed to ultraviolet (UV) light. Iron ions have a role in skin photodamage by participating in the formation of reactive oxygen species. In this study, we evaluated the effect of egg yolk phosvitin on UV-light-induced oxidative stress. Mouse dorsal skin homogenate was exposed to UVA light in the presence or absence of ferric nitrilotriacetate (FeNTA). Lipid peroxidation was determined by measuring thiobarbituric acid-reactive substances (TBARS). The TBARS concentration increased with increasing FeNTA concentration and UV-light-exposure time. In the presence of FeNTA, phosvitin more effectively inhibited in vitro lipid peroxidation than did bovine serum albumin. According to results of electron spin resonance studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent, phosvitin suppressed the formation of hydroxyl radicals. These results suggest that UV-light-induced oxidative stress can be reduced by phosvitin.

Physiological basis for resistance to diphenyl ether herbicides in common waterhemp (Amaranthus rudis)

Common waterhemp seeds were collected from two Missouri soybean fields where biotypes were not controlled by acifluorfen. Plants grown from these seeds were tested for resistance to the diphenyl ether herbicides acifluorfen and lactofen. Resistance to susceptibility (R/S) ratios, calculated as the ratio of the dose required to inhibit dry weight accumulation by 50% (GR50) in resistant plants to that for susceptible plants, were 9.5 and 11 for the Meadville biotype and 28 and 44 for the Bethel biotype exposed to acifluorfen and lactofen, respectively. Electrolyte leakage assays determined that light-induced lipid peroxidation by acifluorfen was greatest on a control population (Bradford), intermediate for the Meadville biotype, and lowest for the Bethel biotype. Levels of the photodynamic pigment protoporphyrin IX (Proto) accumulating in leaf disks exposed to acifluorfen were much lower in the resistant biotypes than in the susceptible wild type, and the level of Proto accumulation was significantly correlated to the degree of membrane disruption. Although the binding of acifluorfen to protoporphyrinogen oxidase in chloroplasts may have been altered in the resistant biotypes, the molecular and biochemical factors involved in the mechanism of resistance remain to be fully characterized. However, this study establishes that the physiological basis for the evolved resistance to diphenyl ethers in common waterhemp rests on the reduction of Proto accumulation.

Singlet Oxygen Quenching Effect of Andaliman (Zanthoxylum acanthopodium DC.) Extracts in Light-Induced Lipid Oxidation

Addition of andaliman extract has been shown to provide increased protection from lipid oxidation during cooking. Although andaliman extract has reported as an effective antioxidant in autoxidized system, no study have been published on its effects on light-induced oxidation or photosensitized oxidation. The objective of this research is to determine singlet oxygen quenching effects of andaliman extract on erythrosine-sensitized photooxidation of linoleic acid and in palm oil. Freeze dried ground andaliman fruit was sequentially extracted first using hexane, followed by acetone, and finally the residue was extracted by ethanol. Each of these three extracts were added to light-induced lipid peroxidation in a reaction system containing linoleic acid or palm oil with the presence of erythrosine as a photo sensitizer. Upon the exposure of fluorescent light at 4000 lux singlet oxygen is presumably formed from triplet oxygen which initiate the lipid peroxidation process. The sequential extraction of andaliman resulted in ethanolic extract containing phenolic compounds consistently show antioxidative activity presumably through singlet oxygen quenching in light-induced lipid peroxidation in either linoleic acid or RBD palm oil reaction mixture containing erythrosine as a photosensitizer. The andaliman hexane and acetone extracts may contain not only phenolic compounds, but also trace amount of plant pigments which resulted in stronger lipid peroxidation effect than the antioxidative effect of phenolic substances, especially at higher level of addition.

Protective effect of Fructus Lycii polysaccharides against time and hyperthermia-induced damage in cultured seminiferous epithelium

Lycium barbarum L. (Solanaceae) is a Chinese medicinal plant whose fruits ( Fructus Lycii) are used by Chinese physicians for treatment of infertility. However, the active ingredients and the mechanism of action underlying Lycium's fertility-facilitating effects remain unknown. Here we report that Fructus Lycii polysaccharides (FLPS) inhibit time- and hyperthermia-induced structural damage in murine seminiferous epithelium, in vitro. Moreover, we found that FLPS delayed apoptosis in this system, both at normothermic and hyperthermic culture conditions. Oxidative stress was reported to be a major cause of structural degradation and apoptosis in hyperthermic testes, and thus the protective effect of FLPS could implicate an antioxidant mechanism of action. To test this hypothesis we assayed the effect of FLPS on ultraviolet light-induced lipid peroxidation, and cytochrome c reduction by free radicals. We found that FLPS is a potent inhibitor of both of these reactions. Together, these results demonstrate the protective effect of FLPS on time- and hyperthermia-induced testicular degeneration in vitro, indicate the potential mechanism of action for this protective effect, and provide a scientific basis for the traditional use of this plant.

Localization of intracellular lipid hydroperoxides using the tetramethylbenzidine reaction for transmission electron microscopy.

Histochemical reactions for lipid hydroperoxides (LHP) using indophenol, benzidine, or phenylendiamine as the electron donor have been described previously for auto-oxidized adipose () and neuronal () tissue. More recently, tetramethylbenzidine (TMB) has been proposed as another chromagen (). The usefulness of the TMB reaction for ultrastructural studies of lipid peroxidation was demonstrated in retina where LPH was generated by incubation with exogenous lipoxygenase. The glutaraldehyde fixed tissue, which was reacted with TMB and then postfixed in osmium tetroxide, showed an electron-dense product (). This technique allows intra- and extracellular localization, as well as a comparison of relative intensity amoung various cell types and subcellular organelles (). In light-induced lipid peroxidation, discs of the outer segments, which are rich in oxidizable long-chain polyunsaturated fatty acids, stain strongly and appear as bubble-like structures (). These are however, quite similar to fingerprint profiles seen acutely in outer segments and chronically in neurons, which are visualized without TMB following exogenous exposure to LHP (,). A possible caveat to the reported method is that peroxidized protein and carbohydrates many also react and so the TMB method has not been proven to be specific for LHP only.