Protective effect of lutein on ARPE-19 cells upon H2O2-induced G2/M arrest

MiR-6837-3p protected retinal epithelial cells from oxidative stress by targeting E2F6

AIM

The mechanism of age-related macular degeneration (AMD) is a complex illness that is not fully understood. Therefore, the aim of this study was to investigate the expression patterns of miR-6837-3p in retinal epithelial cells.

METHODS

H2O2 was used to treat ARPE-19 cells for 2, 4 and 6 h to mimic the in vivo environment of AMD. MiR inhibitors and mimics were used to inhibit or overexpress miR-6837-3p in H2O2-treated ARPE-19 cells, respectively. Then, CCK8 assay, flow cytometry, and wound healing assays were conducted to assess the effects of miR-6837-3p on the behaviors of ARPE-19 cells, including cell growth, apoptosis, cycle progression, and migration. Finally, microRNA database prediction and luciferase reporter assays were used to demonstrate that miR-6837-3p targets the downstream gene E2F6.

RESULTS

H2O2 induced a decrease in cell viability and an increase in ROS levels in a time-dependent manner. Additionally, overexpression of miR-6837-3p increased cell viability and suppressed apoptosis in ARPE-19 cells treated with H2O2. Meanwhile, increased miR-6837-3p promoted cell cycle progression and cell migration of ARPE-19 cells. Finally, miR-6837-3p exerted anti-apoptosis and anti-oxidative stress effects by inhibiting the expression of E2F6 in ARPE-19 cells.

CONCLUSIONS

The MiR-6837-3p/E2F6 axis might be a target for the treatment of AMD to improve ARPE-19 cell function.

Protective effects of carotenoids against blue light induced-cellular damage in human retinal pigment epithelium

The retinal pigmented epithelium (RPE) is constantly exposed to visible light, including blue light (BL) that creates reactive oxygen species (ROS), which are harmful to DNA and induce cellular senescence. Carotenoids are recognized for their antioxidant properties, but their protective effect on DNA repair and cellular senescence under BL induced oxidative stress has not been evaluated. After BL irradiation, the positive senescence-associated-β-galactosidase (SA-β-gal) staining, and gene expression of p16 INK4a and p21 Waf/Cip1 were upregulated in ARPE-19 cells. Pretreatment with carotenoids reduced ROS, p-H2A.X nuclear foci, and SA-β-gal positive cells induced by BL irradiation. Furthermore, pretreatment with carotenoids reduced the secretion of IL-6 and VEGF triggered by BL. Since increased senescent cells and secretion of IL-6 and VEGF are involved in age-related macular degeneration pathogenesis, our results support that carotenoid supplementation has a potential role in protecting the eyes from the deleterious effects of excessive BL exposure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01757-z.

The effect of Fernblock® in preventing blue-light-induced oxidative stress and cellular damage in retinal pigment epithelial cells is associated with NRF2 induction

Blue light exposure of the ocular apparatus is currently rising. This has motivated a growing concern about potential deleterious effects on different eye structures. To address this, ARPE-19 cells were used as a model of the retinal pigment epithelium and subjected to cumulative expositions of blue light. The most relevant cellular events previously associated with blue-light-induced damage were assessed, including alterations in cell morphology, viability, cell proliferation, oxidative stress, inflammation, and the induction of DNA repair cellular mechanisms. Consistent with previous reports, our results provide evidence of cellular alterations resulting from repeated exposure to blue light irradiation. In this context, we explored the potential protective properties of the vegetal extract from Polypodium leucotomos, Fernblock® (FB), using the widely known treatment with lutein as a reference for comparison. The only changes observed as a result of the sole treatment with either FB or lutein were a slight but significant increase in γH2AX+ cells and the raise in the nuclear levels of NRF2. Overall, our findings indicate that the treatment with FB (similarly to lutein) prior to blue light irradiation can alleviate blue-light-induced deleterious effects in RPE cells, specifically preventing the drop in both cell viability and percentage of EdU+ cells, as well as the increase in ROS generation, percentage of γH2AX+ nuclei (more efficiently with FB), and TNF-α secretion (the latter restored only by FB to similar levels to those of the control). On the contrary, the induction in the P21 expression upon blue light irradiation was not prevented neither by FB nor by lutein. Notably, the nuclear translocation of NRF2 induced by blue light was similar to that observed in cells pre-treated with FB, while lutein pre-treatment resulted in nuclear NRF2 levels similar to control cells, suggesting key differences in the mechanism of cellular protection exerted by these compounds. These results may represent the foundation ground for the use of FB as a new ingredient in the development of alternative prophylactic strategies for blue-light-associated diseases, a currently rising medical interest.

Lutein Production and Extraction from Microalgae: Recent Insights and Bioactive Potential

Microalgae have been reported to be excellent producers of bioactive molecules. Lutein is a pigment reported to have various beneficial effects for humans, and especially for eye well-being. In the current review, we summarize various methods that have been developed to optimize its extraction and bioactivities reported for human health. Several protective effects have been reported for lutein, including antioxidant, anticancer, anti-inflammatory, and cardioprotective activity. This review also reports attempts to increase lutein production by microalgae by changing culturing parameters or by using pilot-scale systems. Genetic engineering lutein production is also discussed. Considering the increasing aging of the worldwide population will create an increased need for lutein, a viable economic and eco-sustainable method to produce lutein is needed to face this market demand.

Analysis of Lutein Content in Microencapsulated Marigold Flower Extract (Tagetes erecta L.) Using UHPLC-Q-Orbitrap-HRMS and Its Cytotoxicity in ARPE-19 Cells

Organic solvents are commonly used to extract lutein. However, they are toxic and are not environmental-friendly. There are only a few reports on the quantification of lutein. Therefore, this study aimed to determine a suitable extraction method by which to obtain lutein from marigold flower (Tagetes erecta L.), using coconut oil to evaluate the cytotoxicity of extract in ARPE-19 cells, to optimize the encapsulation process for the development of microencapsulated marigold flower extract, and to develop the method for analysis of lutein by using UHPLC-Q-Orbitrap-HRMS. Coconut oil was used for the extraction of marigold flowers with two different extraction methods: ultrasonication and microwave-assisted extraction. The UHPLC-Q-Orbitrap-HRMS condition for the analysis of lutein was successfully developed and validated. Marigold flower extract obtained using the microwave method had the highest lutein content of 27.22 ± 1.17 mg/g. A cytotoxicity study revealed that 16 µM of lutein from marigold extract was non-toxic to ARPE-19 cells. For the development of microencapsulated marigold extract, the ratio of oil to wall at 1:5 had the highest encapsulation efficiency and the highest lutein content. Extraction of lutein using coconut oil and the microwave method was the suitable method. The microencapsulated marigold extract can be applied for the development of functional ingredients.

Effect of Lutein on Ocular Goblet Cell, IFN-γ, and IL-17 Concentration in Dry Eye-Induced Mice Model

Introduction Dry eye disease affects a substantial number of individuals globally and significantly impacts their quality of life and productivity. Understanding the underlying mechanisms and managing dry eye disease poses substantial challenges. Recent research has highlighted the involvement of various inflammatory mediators in the pathogenesis of dry eye disease, including the cytokines interferon (IFN)-γ and interleukin (IL)-17. Activation of stress signaling pathways and residential immune cells on the ocular epithelial surface ignites epithelial changes, destabilizes tear film, amplifies inflammation and creates an endless loop. Lutein is a β-carotenoid antioxidant which has been proven to be beneficial in many ocular diseases due to its protective and anti-inflammatory effect induced by various stimulators. Lutein also acts as a direct and indirect antioxidant agent, suppressing oxidative stress and mitigating oxidative damage. The purpose of this research is to investigate the potential therapeutic effects of lutein in a mouse model of dry eye, aiming to elucidate its impact on ocular manifestation, goblet cells count, IFN-γ and IL-17 level. Methods Desiccating stress was induced in C57BL/6 mice. In a separate group, lutein was administered subcutaneously on a daily basis throughout the experimental period. Clinical manifestations of dry eye, including ocular surface changes, were documented photographically. Goblet cell concentration was assessed through Periodic Acid-Schiff (PAS) staining, and the levels of IFN-γ and IL-17 were measured using enzyme-linked immunosorbent assay (ELISA). Data obtained from these assessments were compared between the experimental groups to determine the potential effects of lutein on dry eye pathology and cytokine levels. Results Significant differences were observed in clinical observations and goblet cell concentrations among the groups; however, no statistically significant differences were found in the levels of IFN-γ and IL-17 between the groups. The untreated group exhibited significantly higher opacities and irregularities compared to the lutein-treated group, whereas the mean goblet cell count was highest in the lutein-treated group. Conclusion Lutein administration improves clinical observations and goblet cell concentrations in a mouse model of dry eye. The treated group exhibited improved ocular surface integrity, but no significant differences in the tested cytokine levels were observed. These findings suggest that lutein supplementation could be a promising therapeutic option for managing dry eye disease. Further research is needed to understand the underlying mechanisms and long-term effects of lutein in dry eye management.

Changes in the Expression Profile of Pyroptosis-Related Genes in Senescent Retinal Pigment Epithelial Cells after Lutein Treatment

Retinal pigment epithelium (RPE) is a specialized structure essential for proper vision, which is constantly exposed to oxidative damage. With aging, this damage accumulates within the RPE cells, causing various diseases, including age-related macular degeneration (AMD). Numerous antioxidant substances are used to prevent this process in humans, including lutein. This study aims to determine the differences in the expression patterns of pyroptosis genes in senescent human retinal pigment epithelial cell line ARPE-19 exposed to lutein. Changes in the expression of pyroptosis-related genes were assessed by oligonucleotide microarrays, and the results were validated by real-time RT-qPCR. The microarray analysis showed seven transcripts were differentially expressed both in the H₂O₂-treated cells versus the controls and in the lutein/H₂O₂-treated cells compared to the H₂O₂-treated cells (FC > 2.0). Depending on the used lutein, H₂O₂, or co-treatment of ARPE-19 cells, statistically significant differences in the expression of TXNIP, CXCL8, BAX, and CASP1 genes were confirmed by the RT-qPCR (p < 0.05). A STRING database analysis showed that the proteins encoded by the analyzed genes form a strong interaction network (p < 0.001). These data indicate that lutein modulates the expression level of pyroptosis-related genes, which may be useful for the development of new methods preventing pyroptosis pathway activation in the future.

Safety Profile of Lutein- Versus Triamcinolone Acetonide-Based Vitreous Staining

Purpose

To assess the safety profile of a new lutein-based vitreous dye (LB-VD) formulation compared with various triamcinolone acetonide (TA) formulations with and without subsequent exposure to perfluorodecalin (PFD) in vitro.

Methods

Human adult retinal pigment epithelial cells (ARPE-19) were treated with the following formulations: undiluted preserved TA (TA-BA), diluted preserved TA (D-TA-BA), preservative-free TA (TA-PF), and LB-VD. First, cell tolerability was evaluated with MTT, LDH, and ATPlite assays after 1, 5, and 30 minutes of exposure to each tested formulation. Then, cells were sequentially exposed to formulations and PFD. After 24 hours of exposure to PFD, cell tolerability was evaluated through MTT and ATPlite assays.

Results

Among the formulations tested, LB-VD showed the highest levels of cell viability, cell metabolism, and cell proliferation and induced the lowest release of LDH, whereas the TA-based formulations demonstrated a cytotoxic effect on ARPE-19 cells in vitro. After subsequent 24-hour exposure to PFD, a greater reduction of cell viability was noted for all the formulations; however, this reduction was not significant only for the combination LB-VD-PFD, which was the best tolerated condition.

Conclusions

LB-VD showed a better safety profile compared with all TA-based formulations, even when used in combination with PFD.

Translational Relevance

In surgical practice, LB-VD may be preferred to TA-based formulations for vitreous staining in the light of its more favorable safety profile.

Cordyceps militaris Carotenoids Protect Human Retinal Endothelial Cells against the Oxidative Injury and Apoptosis Resulting from H2O2

Vision loss is primarily caused by age-related macular degeneration (AMD) due to oxidative retinal pigment epithelial (RPE) cell injury. Carotenoid utilization is deemed a possible strategy for treating AMD. Cordyceps militaris has advantages like immunomodulatory, anti-inflammatory, and antioxidative characteristics. This paper assessed the possible protective influence of carotenoids obtained by isolating and purifying the Cordyceps militaris (CMCT) into human RPE cells (ARPE-19) damaged by hydrogen peroxide (H₂O₂). The findings demonstrated that CMCT safeguarded the ARPE-19 cells against the damage and apoptosis caused by H₂O₂ and oxidative stress via Bcl-2 protein upregulation, as well as the expression of Bax and cleaved caspase-3 protein. In addition, CMCT treatment increased cell survival and restricted the generation of H₂O₂-induced reactive oxygen species (ROS) and the protein expression of NADPH oxidase-1 (NOX1). Additionally, the CMCT treatment of H₂O₂-induced ARPE-19 cells ameliorated high malondialdehyde (MDA) levels in oxidative stress-induced cells. The catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH) returned to standard levels, which were governed by the higher expression of nuclear Nrf2 protein in the ARPE-19 cells. Moreover, this study showed that CMCT safeguarded the ARPE-19 cells against the damage caused by oxidative stress via its antioxidant activity and antiapoptotic functionality, suggesting the potential therapeutic role of CMCT in AMD prevention and mitigation.

Nanoscale Delivery Systems of Lutein: An Updated Review from a Pharmaceutical Perspective

Carotenoids are natural lipid-soluble pigments that produce yellow to red colors in plants as well as providing bright coloration in vegetables and fruits. Lutein belongs to the xanthophyll subgroup of the carotenoid family, which plays an essential role in photosynthesis and photoprotection in nature. In the human body, lutein, together with its isomer zeaxanthin and its metabolite meso-zeaxanthin, accumulates in the macula of the eye retina, which is responsible for central, high-resolution, and color vision. As a bioactive phytochemical, lutein has essential physiological functions, providing photoprotection against damaging blue light, along with the neutralization of oxidants and the preservation of the structural and functional integrity of cellular membranes. As a potent antioxidant and anti-inflammatory agent, lutein unfortunately has a low bioavailability because of its lipophilicity and a low stability as a result of its conjugated double bonds. In order to enhance lutein stability and bioavailability and achieve its controlled delivery to a target, nanoscale delivery systems, which have great potential for the delivery of bioactive compounds, are starting to be employed. The current review highlights the advantages and innovations associated with incorporating lutein within promising nanoscale delivery systems, such as liposomes, nanoemulsions, polymer nanoparticles, and polymer–lipid hybrid nanoparticles, as well as their unique physiochemical properties.

Arbutin Protects Retinal Pigment Epithelium Against Oxidative Stress by Modulating SIRT1/FOXO3a/PGC-1α/β Pathway

Age-related macular degeneration (AMD), which is the leading cause of blindness among the elderly in western societies, is majorly accompanied by retinal pigment epithelium (RPE) degeneration. Because of the irreversible RPE cell loss among oxidative stress, it is crucial to search for available drugs for atrophic (dry) AMD. RNA-Seq analysis revealed that genes related to aging and mitochondrial health were differentially expressed under Arbutin treatment, whereas compared to oxidative injury, our study demonstrated that Arbutin substantially abrogated oxidative stress-induced cell senescence and apoptosis linked to intracellular antioxidant enzyme system homeostasis maintenance, restored mitochondrial membrane potential (MMP), and reduced the SA-β-GAL accumulation in RPE. Furthermore, Arbutin alleviated oxidative stress-mediated cell apoptosis and senescence via activation of SIRT1, as evidenced by the increase of the downstream FoxO3a and PGC-1α/β that are related to mitochondrial biogenesis, and the suppression of NF-κB p65 inflammasome, whereas rehabilitation of oxidative stress by SIRT1 inhibitor attenuated the protective effect of Arbutin. In conclusion, we validated the results in an in vivo model constructed by NAIO₃-injured mice. OCT and HE staining showed that Arbutin sustained retinal integrity in the case of oxidative damage in vivo, and the disorder of RPE cytochrome was alleviated through fundus observation. In summary, our findings identified that oxidative stress-induced mitochondrial malfunction and the subsequent senescence acceleration in RPE cells, whereas Arbutin inhibited TBHP-induced RPE degeneration via regulating the SIRT1/Foxo3a/PGC-1α/β signaling pathway. These findings suggested that Arbutin is a new agent with potential applications in the development of AMD diseases.

Integrative Analysis of Metabolomic and Transcriptomic Data Reveals the Antioxidant Potential of Dietary Lutein in Chickens

Lutein can increase the body's skin color and has antioxidant potential. However, how it affects lipid metabolism and oxidative stress in chickens remains unknown. In this study, 74-day-old male chickens raised on feed supplemented with lutein had higher hip, back, breast, leg, shin and abdominal fat yellowness than the control group, and the livers of chickens in the lutein group had higher superoxide dismutase and glutathione peroxidase and lower malondialdehyde activities. To clarify the potential regulatory network regulated by lutein, we used RNA-seq and nontargeted metabolomics to detect changes in the male chicken liver and plasma, respectively. A total of 243 differentially expressed genes were significantly enriched in cytokine–cytokine receptor interaction signaling pathways, among others. A total of 237 significantly different metabolites were enriched in lysine biosynthesis and degradation and glycerophospholipid metabolism signaling pathways, among others. Finally, we comprehensively analyzed metabolome and transcriptome data and found that many differentially expressed genes and significantly different metabolites play crucial roles in lipid metabolism and oxidative stress. In summary, dietary lutein can improve male chicken skin yellowness and antioxidant indices and affect liver gene expression and plasma metabolites and may help improve the health of chickens.

Low-dose melittin is safe for intravitreal administration and ameliorates inflammation in an experimental model of uveitis

Uveitis is a group of sight-threatening ocular inflammatory disorders, whose mainstay of therapy is associated with severe adverse events, prompting the investigation of alternative treatments. The peptide melittin (MEL) is the major component of Apis mellifera bee venom and presents anti-inflammatory and antiangiogenic activities, with possible application in ophthalmology. This work aims to investigate the potential of intravitreal MEL in the treatment of ocular diseases involving inflammatory processes, especially uveitis. Safety of MEL was assessed in retinal cells, chick embryo chorioallantoic membranes, and rats. MEL at concentrations safe for intravitreal administration showed an antiangiogenic activity in the chorioallantoic membrane model comparable to bevacizumab, used as positive control. A protective anti-inflammatory effect in retinal cells stimulated with lipopolysaccharide (LPS) was also observed, without toxic effects. Finally, rats with bacille Calmette-Guerin- (BCG) induced uveitis treated with intravitreal MEL showed attenuated disease progression and improvement of clinical, morphological, and functional parameters, in addition to decreased levels of proinflammatory mediators in the posterior segment of the eye. These effects were comparable to the response observed with corticosteroid treatment. Therefore, MEL presents adequate safety profile for intraocular administration and has therapeutic potential as an anti-inflammatory and antiangiogenic agent for ocular diseases.

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Melittin at low concentration is safe for intravitreal administration.

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The antiangiogenic effect of melittin on the chorioallantoic membrane model is comparable to bevacizumab.

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Melittin protects retinal cells from inflammatory response induced by lipopolysaccharide.

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Melittin improves clinical, functional and morphological signs of inflammation in rats with BCG-induced uveitis.

The Age-Related Macular Degeneration (AMD)-Preventing Mechanism of Natural Products

Age-related macular degeneration (AMD) is related to central visual loss in elderly people and, based on the increment in the percentage of the aging population, the number of people suffering from AMD could increase. AMD is initiated by retinal pigment epithelium (RPE) cell death, finally leading to neovascularization in the macula lutea. AMD is an uncurable disease, but the symptom can be suppressed. The current therapy of AMD can be classified into four types: device-based treatment, anti-inflammatory drug treatment, anti-vascular endothelial growth factor treatment, and natural product treatment. All these therapies have adverse effects, however early AMD therapy used with products has several advantages, as it can prevent RPE cell apoptosis in safe doses. Cell death (apoptosis) is caused by various factors, such as oxidative stress, inflammation, carbonyl stress, and a deficiency in essential components for cells, and RPE cell death is related to oxidative stress, inflammation, and carbonyl stress. Some natural products have anti-oxidative effects, anti-inflammation effects, and/or anti-carbonylation effects. The AMD preventive mechanism of natural products varies, with some natural products activating one or more anti-apoptotic pathways, such as the Nrf2/HO-1 anti-oxidative pathway, the anti-inflammasome pathway, and the anti-carbonyl pathway. As AMD drug candidates from natural products effectively inhibit RPE cell death, they have the potential to be developed as drugs for preventing early (dry) AMD.

Lutein nanodisks protect human retinal pigment epithelial cells from UV light-induced damage

The hydrophobic carotenoid, lutein, was conferred with aqueous solubility upon formulation into reconstituted discoidal high density lipoprotein particles, termed lutein nanodisks (ND). When formulated with phosphatidylcholine (PC), apolipoprotein (apo) A-I and lutein (formulation ratio = 5 mg PC/2 mg apoA-I/1 mg lutein), lutein solubilization efficiency in phosphate buffered saline (PBS) was ~90%. The UV/Vis absorbance maxima for lutein ND in PBS were red shifted by 6-13 nm versus the corresponding lutein absorbance maxima in ethanol. FPLC gel filtration chromatography gave rise to a single major absorbance peak in the size range of ND. Incubation of cultured ARPE-19 cells with lutein ND resulted in lutein uptake, as determined by HPLC analysis of cell extracts. Compared to control incubations, ARPE-19 cells incubated with lutein ND were protected from UV light-induced loss of cell viability. Consistent with this, reactive oxygen species generation, induced by exposure to UV irradiation, was lower in lutein-enriched cells than in control cells. Thus, uptake of ND-associated lutein protects ARPE-19 cells from UV light-induced damage. Taken together, the data indicate ND provide an aqueous lutein delivery vehicle for biotechnological or therapeutic applications.

Medication Trends for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is central vision loss with aging, was the fourth main cause of blindness in 2015, and has many risk factors, such as cataract surgery, cigarette smoking, family history, hypertension, obesity, long-term smart device usage, etc. AMD is classified into three categories: normal AMD, early AMD, and late AMD, based on angiogenesis in the retina, and can be determined by bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E)-epoxides from the reaction of A2E and blue light. During the reaction of A2E and blue light, reactive oxygen species (ROS) are synthesized, which gather inflammatory factors, induce carbonyl stress, and finally stimulate the death of retinal pigment epitheliums (RPEs). There are several medications for AMD, such as device-based therapy, anti-inflammatory drugs, anti-VEGFs, and natural products. For device-based therapy, two methods are used: prophylactic laser therapy (photocoagulation laser therapy) and photodynamic therapy. Anti-inflammatory drugs consist of corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). Anti-VEGFs are classified antibodies for VEGF, aptamer, soluble receptor, VEGF receptor-1 and -2 antibody, and VEGF receptor tyrosine kinase inhibitor. Finally, additional AMD drug candidates are derived from natural products. For each medication, there are several and severe adverse effects, but natural products have a potency as AMD drugs, as they have been used as culinary materials and/or traditional medicines for a long time. Their major application route is oral administration, and they can be combined with device-based therapy, anti-inflammatory drugs, and anti-VEGFs. In general, AMD drug candidates from natural products are more effective at treating early and intermediate AMD. However, further study is needed to evaluate their efficacy and to investigate their therapeutic mechanisms.

Inhibition of Melanoma Cells A375 by Carotenoid Extract and Nanoemulsion Prepared from Pomelo Leaves

This study aims to determine carotenoids in pomelo leaves (Citrus grandis Osbeck), a rich source of nutrients and phytochemicals, by high-performance liquid chromatography-mass spectrometry and prepare carotenoid nanoemulsions for the study of its inhibitory mechanism on melanoma cells A375. Fourteen carotenoids were separated within 27 min by using a YMC-C30 column and a gradient mobile phase of methanol-acetonitrile-water (84:14:2, v/v/v) and methylene chloride with a flow rate of 1 mL/min and detection wavelength of 450 nm. All-trans-lutein plus its cis-isomers were present in the largest amount (3012.97 μg/g), followed by all-trans-neoxanthin (309.2 μg/g), all-trans-violaxanthin (208.5 μg/g), all-trans-β-carotene plus its cis-isomers (203.17 μg/g), all-trans-α-carotene plus its cis-isomers (152.5 μg/g), all-trans-zeaxanthin (54.67 μg/g), and all-trans-β-cryptoxanthin plus its cis-isomers (24.56 μg/g). A stable carotenoid nanoemulsion was prepared with a mean particle size of 13.3 nm, zeta-potential of -66.6 mV, a polydispersity index of 0.132 and an encapsulation efficiency of 99%. Both the carotenoid extract and nanoemulsion could upregulate p53, p21, cyclin B and cyclin A expressions in melanoma A375 cells and downregulate CDK1 and CDK2 in a concentration-dependent manner. Also, they could upregulate Bax and cytochrome-C and downregulate Bcl-2, leading to cell apoptosis through activation of caspase-9, caspase-8 and caspase-3. Compared to extract, carotenoid nanoemulsion was shown to be more effective in inhibiting the growth of melanoma cells A375. This finding further demonstrated that a carotenoid nanoemulsion prepared from pomelo leaves possessed a great potential to be developed into functional foods or even botanic drugs.

Lutein as a Modulator of Oxidative Stress-Mediated Inflammatory Diseases

Lutein is a xanthophyll carotenoid obtained from various foods, such as dark green leafy vegetables and egg yolk. Lutein has antioxidant activity and scavenges reactive oxygen species such as singlet oxygen and lipid peroxy radicals. Oxidative stress activates inflammatory mediators, leading to the development of metabolic and inflammatory diseases. Thus, recent basic and clinical studies have investigated the anti-inflammatory effects of lutein based on its antioxidant activity and modulation of oxidant-sensitive inflammatory signaling pathways. Lutein suppresses activation of nuclear factor-kB and signal transducer and activator of transcription 3, and induction of inflammatory cytokines (interleukin-1β, interleukin-6, monocyte chemoattratant protein-1, tumor necrosis factor-α) and inflammatory enzymes (cyclooxygenase-2, inducible nitric oxide synthase). It also maintains the content of endogenous antioxidant (glutathione) and activates nuclear factor erythroid 2–related factor 2 (Nrf2) and Nrf2 signaling-related antioxidant enzymes (hemeoxygenase-1, NAD(P)H: quinone oxidoreductase 1, glutathione-s-transferase, glutathione peroxidase, superoxide dismutase, catalase). In this review, we have discussed the current knowledge regarding the anti-inflammatory function of lutein against inflammatory diseases in various organs, including neurodegenerative disorders, eye diseases, diabetic retinopathy, osteoporosis, cardiovascular diseases, skin diseases, liver injury, obesity, and colon diseases.

SS-31 protect retinal pigment epithelial cells from H2 O2 -induced cell injury by reducing apoptosis

Evidence has shown that effects from oxidative stress induced damage of retinal or human retinal pigment epithelial (RPE) cells. Antioxidant supplementation is a plausible strategy to avoid oxidative stress and maintain the function of retina. d-Arg-2,6-dimethyltyrosine-Lys-Phe-NH2 (SS-31) has been used in the treatment of many diseases. In this study, we found that SS-31 attenuated hydrogen peroxide (H2 O2 )-induced loss of cell viability, reduced oxidative damage and cell apoptosis in RPE cells. HO-1, Trx-1 and Nrf-2 expression levels significantly increased on pre-treatment with SS-31 compared with the H2 O2 group. SS-31 inhibited apoptosis through the downregulation of Bax and the upregulation of Bcl-2. Our results suggest that SS-31 had a protective effect against H2 O2 treatment in ARPE-19 cells by enhancing the antioxidative enzymes expression and decreasing apoptosis, which could be considered a promising therapeutic intervention for retinal degeneration.

Protective Effects of a Lutein Ester Prodrug, Lutein Diglutaric Acid, against H2O2-Induced Oxidative Stress in Human Retinal Pigment Epithelial Cells

Oxidative stress-induced cell damage and death of the retinal pigmented epithelium (RPE), a polarized monolayer that maintains retinal health and homeostasis, lead to the development of age-related macular degeneration (AMD). Several studies show that the naturally occurring antioxidant Lutein (Lut) can protect RPE cells from oxidative stress. However, the poor solubility and low oral bioavailability limit the potential of Lut as a therapeutic agent. In this study, lutein diglutaric acid (Lut-DG), a prodrug of Lut, was synthesized and its ability to protect human ARPE-19 cells from oxidative stress was tested compared to Lut. Both Lut and Lut-DG significantly decreased H₂O₂-induced reactive oxygen species (ROS) production and protected RPE cells from oxidative stress-induced death. Moreover, the immunoblotting analysis indicated that both drugs exerted their protective effects by modulating phosphorylated MAPKs (p38, ERK1/2 and SAPK/JNK) and downstream molecules Bax, Bcl-2 and Cytochrome c. In addition, the enzymatic antioxidants glutathione peroxidase (GPx) and catalase (CAT) and non-enzymatic antioxidant glutathione (GSH) were enhanced in cells treated with Lut and Lut-DG. In all cases, Lut-DG was more effective than its parent drug against oxidative stress-induced damage to RPE cells. These findings highlight Lut-DG as a more potent compound than Lut with the protective effects against oxidative stress in RPE cells through the modulation of key MAPKs, apoptotic and antioxidant molecular pathways.

Applications of Hyaluronic Acid in Ophthalmology and Contact Lenses

Hyaluronic acid (HA) is a glycosaminoglycan that was first isolated and identified from the vitreous body of a bull’s eye. HA is ubiquitous in the soft connective tissues of animals and therefore has high tissue compatibility for use in medication. Because of HA’s biological safety and water retention properties, it has many ophthalmology-related applications, such as in intravitreal injection, dry eye treatment, and contact lenses. Due to its broad range of applications, the identification and quantification of HA is a critical topic. This review article discusses current methods for analyzing HA. Contact lenses have become a widely used medical device, with HA commonly used as an additive to their production material, surface coating, and multipurpose solution. HA molecules on contact lenses retain moisture and increase the wearer’s comfort. HA absorbed by contact lenses can also gradually release to the anterior segment of the eyes to treat dry eye. This review discusses applications of HA in ophthalmology.

Pharmacological inhibition of mitochondrial fission attenuates oxidative stress-induced damage of retinal pigmented epithelial cells

Mitochondria maintain their function by the process of mitochondrial dynamics, which involves repeated fusion and fission. It is thought that the failure of mitochondrial dynamics, especially excessive fission, is related to the progression of several diseases. A previous study demonstrated that mitochondrial fragmentation occurs in the retinal pigmented epithelial (RPE) cells of patients with non-exudative age-related macular degeneration (AMD). We predicted that the suppression of mitochondrial fragmentation offers a novel therapeutic strategy for non-exudative AMD. We investigated whether the inhibition of mitochondrial fission was effective against the oxidative stress-induced damage of ARPE-19 cells. The treatment of ARPE-19 cells with H₂O₂ caused mitochondrial fragmentation, but treatment with mitochondrial division inhibitor 1 (Mdivi-1) suppressed fragmentation. Additionally, Mdivi-1 protected ARPE-19 cells against H₂O₂-induced damage, and suppressed the release of cytochrome c from the mitochondria. Mitochondrial function was evaluated by staining with JC-1 and measuring the production of reactive oxygen species (ROS), which revealed that mitochondrial function improved in the Mdivi-1-treated group. These findings indicated that the inhibition of mitochondrial fission would be a novel therapeutic target for non-exudative AMD.

Chitosan-sodium alginate-fatty acid nanocarrier system: Lutein bioavailability, absorption pharmacokinetics in diabetic rat and protection of retinal cells against H2O2 induced oxidative stress in vitro

Aiming to enhance therapeutic efficiency of lutein, lutein loaded chitosan-sodium alginate (CS-SA) based nanocarrier system (LNCs) were prepared and evaluated for lutein bioavailability and pharmacokinetics in diabetic rats in comparison to micellar lutein (control). Further, cytotoxicity, cellular uptake and protective activity against H₂O₂ induced oxidative stress in ARPE-19 cells were studied. Results revealed that LNCs displayed maximal lutein AUC in plasma, liver and eye respectively in normal (3.1, 2.7 and 5.2 folds) and diabetic (7.3, 3.4 and 2.8 folds) rats. Lutein from LNCs exhibited a higher half-life time, mean residence time and slow clearance from the plasma, indicating prolonged circulation compared to control. In ARPE-19 cells, pre-treatment with LNCs (10 μM) have significantly attenuated H₂O₂ induced cell death, intracellular ROS and mitochondrial membrane potential compared to control. In conclusion, LNCs improve the lutein bioavailability in conditions like diabetes, diabetic retinopathy and cataract to curtail oxidative stress in retinal cells.

Spermidine Attenuates Oxidative Stress-Induced Apoptosis via Blocking Ca2+ Overload in Retinal Pigment Epithelial Cells Independently of ROS

Retinal pigment epithelial (RPE) cells occupy the outer layer of the retina and perform various biological functions. Oxidative damage to RPE cells is a major risk factor for retinal degeneration that ultimately leads to vision loss. In this study, we investigated the role of spermidine in a hydrogen peroxide (H₂O₂)-induced oxidative stress model using human RPE cells. Our findings showed that 300 μM H₂O₂ increased cytotoxicity, apoptosis, and cell cycle arrest in the G2/M phase, whereas these effects were markedly suppressed by 10 μM spermidine. Furthermore, spermidine significantly reduced H₂O₂-induced mitochondrial dysfunction including mitochondrial membrane potential and mitochondrial activity. Although spermidine displays antioxidant properties, the generation of intracellular reactive oxygen species (ROS) upon H₂O₂ insult was not regulated by spermidine. Spermidine did suppress the increase in cytosolic Ca²⁺ levels resulting from endoplasmic reticulum stress in H₂O₂-stimulated human RPE cells. Treatment with a cytosolic Ca²⁺ chelator markedly reversed H₂O₂-induced cellular dysfunction. Overall, spermidine protected against H₂O₂-induced cellular damage by blocking the increase of intracellular Ca²⁺ independently of ROS. These results suggest that spermidine protects RPE cells from oxidative stress, which could be a useful treatment for retinal diseases.

Inhibition of oxidative stress induced-cytotoxicity by coptisine in V79-4 Chinese hamster lung fibroblasts through the induction of Nrf-2 mediated HO-1 expression

BACKGROUND

Coptisine is a natural alkaloid compound and is known to have multiple beneficial effects including antioxidant activity. However, whether it can protect lung fibroblasts from oxidative damage has not been studied yet.

OBJECTIVES

To investigate the potential inhibitory effect of coptisine against oxidative stress in V79-4 lung fibroblast cells.

METHODS

V79-4 cells were treated with H₂O₂ (1 mM) in the presence or absence of coptisine (50 µg/ml), N-acetyl cysteine (NAC, 10 mM) or zinc protoporphyrin IX (ZnPP, 10 µM) for the indicated times. The alleviating effects of coptisine on cytotoxicity, cell cycle arrest, apoptosis, reactive oxygen species (ROS) production, DNA damage, mitochondrial dynamics, and inhibition of ATP production against H₂O₂ were investigated. Western blot analysis was used to analyze the expression levels of specific proteins.

RESULTS

Coptisine inhibited H₂O₂-induced cytotoxicity and DNA damage by blocking abnormal ROS generation. H₂O₂ treatment caused cell cycle arrest at the G2/M phase accompanied by increased expression of cyclin-dependent kinase (Cdk) inhibitor p21^WAF1/CIP1 and decreased expression of cyclin B1 and cyclin A. However, these effects were attenuated in the presence of coptisine or NAC. Coptisine also prevented apoptosis by decreasing the rate of Bax/Bcl-2 expression in H₂O₂-stimulated cells and suppressing the loss of mitochondrial membrane potential and the cytosolic release of cytochrome c. In addition, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was markedly promoted by coptisine in the presence of H₂O₂. However, zinc protoporphyrin IX, a potent inhibitor of HO-1, attenuated the ROS scavenging and anti-apoptotic effects of coptisine.

CONCLUSIONS

Based on current data, we suggest that coptisine can be used as a potential treatment for oxidative stress-related lung disease.

Nicotine Prevents Oxidative Stress-Induced Hippocampal Neuronal Injury Through α7-nAChR/Erk1/2 Signaling Pathway

Oxidative stress-induced neuronal damage has been implicated to play a dominant role in neurodegenerative disorders, such as Alzheimer’s disease (AD). Nicotine, a principal additive compound for tobacco users, is thought as a candidate to attenuate amyloid-β-mediated neurotoxicity and NMDA-induced excitotoxicity. Previous studies demonstrated that nicotine exerted this neuroprotective action on oxidative stress. However, the mechanisms underlying how nicotine contributes on oxidative injury in immortalized hippocampal HT-22 cells remain largely unknown. Therefore, in this study we investigated that the potential effects of nicotine on hydrogen peroxide (H₂O₂)-induced oxidative injury and underlying mechanisms in HT-22 cells. We found that pretreatment with nicotine at low concentrations markedly recovered the cell cycle that was arrested at the G2/M phase in the presence of H₂O₂ through reduced intracellular ROS generation. Moreover, nicotine attenuated H₂O₂-induced mitochondrial dysfunctions. Mechanistically, the application of nicotine significantly upregulated the levels of phosphorylated Erk1/2. The neuroprotective effects of nicotine, in turn, were abolished by PD0325901, a selective Erk1/2 inhibitor. Further obtained investigation showed that nicotine exerted its neuroprotective effects via specifically activating α7 nicotinic acetylcholine receptors (α7-nAChRs). A selective inhibitor of α7-nAChRs, methyllycaconitine citrate (MLA), not only completely prevented nicotine-mediated antioxidation but also abolished expression of p-Erk1/2. Taken together, our findings suggest that nicotine suppresses H₂O₂-induced HT-22 cell injury through activating the α7-nAChR/Erk1/2 signaling pathway, which indicates that nicotine may be a novel strategy for the treatment of neurodegenerative disorders.

Cell Cycle Deficits in Neurodegenerative Disorders: Uncovering Molecular Mechanisms to Drive Innovative Therapeutic Development

Cell cycle dysregulation has been implicated in the pathogenesis of neurodegenerative disorders. Specialised function obligates neuronal cells to subsist in a quiescent state of cell cycle once differentiated and therefore the circumstances and mechanisms underlying aberrant cell cycle activation in post-mitotic neurons in physiological and disease conditions remains an intriguing area of research. There is a strict requirement of concurrence to cell cycle regulation for neurons to ensure intracellular biochemical conformity as well as interrelationship with other cells within neural tissues. This review deliberates on various mechanisms underlying cell cycle regulation in neuronal cells and underscores potential implications of their non-compliance in neural pathology. Recent research suggests that successful duplication of genetic material without subsequent induction of mitosis induces inherent molecular flaws that eventually assert as apoptotic changes. The consequences of anomalous cell cycle activation and subsequent apoptosis are demonstrated by the increased presence of molecular stress response and apoptotic markers. This review delineates cell cycle events under normal physiological conditions and deficits amalgamated by alterations in protein levels and signalling pathways associated with cell-division are analysed. Cell cycle regulators essentially, cyclins, CDKs, cip/kip family of inhibitors, caspases, bax and p53 have been identified to be involved in impaired cell cycle regulation and associated with neural pathology. The pharmacological modulators of cell cycle that are shown to impart protection in various animal models of neurological deficits are summarised. Greater understanding of the molecular mechanisms that are indispensable to cell cycle regulation in neurons in health and disease conditions will facilitate targeted drug development for neuroprotection.

Lutein Supplementation for Eye Diseases

Lutein is one of the few xanthophyll carotenoids that is found in high concentration in the macula of human retina. As de novo synthesis of lutein within the human body is impossible, lutein can only be obtained from diet. It is a natural substance abundant in egg yolk and dark green leafy vegetables. Many basic and clinical studies have reported lutein's anti-oxidative and anti-inflammatory properties in the eye, suggesting its beneficial effects on protection and alleviation of ocular diseases such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, myopia, and cataract. Most importantly, lutein is categorized as Generally Regarded as Safe (GRAS), posing minimal side-effects upon long term consumption. In this review, we will discuss the chemical structure and properties of lutein as well as its application and safety as a nutritional supplement. Finally, the effects of lutein consumption on the aforementioned eye diseases will be reviewed.

Copper mediates mitochondrial biogenesis in retinal pigment epithelial cells

Age related macular degeneration (AMD) is a multifactorial disease with genetic, biochemical and environmental risk factors. We observed a significant increase in copper levels in choroid-RPE from donor eyeballs with AMD. Adult retinal pigment epithelial cells (ARPE19 cells) exposed to copper in-vitro showed a 2-fold increase in copper influx transporter CTR1 and copper uptake at 50 μM concentration. Further there was 2-fold increase in cytochrome C oxidase activity and a 2-fold increase in the mRNA expression of NRF 2 with copper treatment. There was a significant increase in mitochondrial biogenesis markers PGC1β and TFAM which was confirmed by mitochondrial mass and copy number. On the contrary, in AMD choroid-RPE, the CTR1 mRNA was found to be significantly down-regulated compared to its respective controls. SCO1 and PGC1β mRNA showed an increase in choroid-RPE. Our study proposes copper to play an important role in mitochondrial biogenesis in RPE cells.

Curcumin Inhibits Proliferation and Epithelial-Mesenchymal Transition in Lens Epithelial Cells through Multiple Pathways

Background

Posterior capsule opacification (PCO), a complication of extracapsular lens extraction surgery that causes visual impairment, is characterized by aberrant proliferation and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). Curcumin, exerting inhibitive effects on cell proliferation and EMT in cancer, serves as a possible antidote towards PCO.

Methods

Cellular proliferation of LECs after treatment of curcumin was measured with MTT assay and flow cytometry. The transcriptional and expressional levels of proteins related to proliferation and EMT of LECs were quantified by western blotting and real-time PCR.

Results

Curcumin was found to suppress the proliferation of LECs by inducing G₂/M arrest via possible inhibition of cell cycle-related proteins including CDK1, cyclin B1, and CDC25C. It had also inactivated proliferation pathways involving ERK1/2 and Akt pathways in LECs. On the other hand, curcumin downregulated the EMT of LECs through blocking the TGF-β/Smad pathway and interfering Notch pathway which play important roles in PCO.

Conclusions

This study shows that curcumin could suppress the proliferation and EMT in LECs, and it might be a potential therapeutic protection against visual loss induced by PCO.

Cytoprotective Effects of Natural Highly Bio-Available Vegetable Derivatives on Human-Derived Retinal Cells

Retinal pigment epithelial cells are crucial for retina maintenance, making their cytoprotection an excellent way to prevent or slow down retinal degeneration. In addition, oxidative stress, inflammation, apoptosis, neovascularization, and/or autophagy are key pathways involved in degenerative mechanisms. Therefore, here we studied the effects of curcumin, lutein, and/or resveratrol on human retinal pigment epithelial cells (ARPE-19). Cells were incubated with individual or combined agent(s) before induction of (a) H₂O₂-induced oxidative stress, (b) staurosporin-induced apoptosis, (c) CoCl₂-induced hypoxia, or (d) a LED-autophagy perturbator. Metabolic activity, cellular survival, caspase 3/7 activity (casp3/7), cell morphology, VEGF levels, and autophagy process were assessed. H₂O₂ provoked a reduction in cell survival, whereas curcumin reduced metabolic activity which was not associated with cell death. Cell death induced by H₂O₂ was significantly reduced after pre-treatment with curcumin and lutein, but not resveratrol. Staurosporin increased caspase-3/7 activity (689%) and decreased cell survival by 32%. Curcumin or lutein protected cells from death induced by staurosporin. Curcumin, lutein, and resveratrol were ineffective on the increase of caspase 3/7 induced by staurosporin. Pre-treatment with curcumin or lutein prevented LED-induced blockage of autophagy flux. Basal-VEGF release was significantly reduced by lutein. Therefore, lutein and curcumin showed beneficial protective effects on human-derived retinal cells against several insults.

Combination of Lutein and Zeaxanthin, and DHA Regulated Polyunsaturated Fatty Acid Oxidation in H2O2-Stressed Retinal Cells

Photochemical and oxidative damages in retinal pigment epithelial (RPE) cells are key events in the pathogenesis of age-related macular degeneration. Polyunsaturated fatty acids (PUFA) and carotenoids are rich in retinal cells, and under oxidative stress leads to oxidation and release lipid mediators. We evaluated the impact of carotenoids (lutein, zeaxanthin) and docosahexaenoic acid (DHA) supplementation on RPE cells under oxidative stress. ARPE-19 cells were exposed to H₂O₂ after pre-treatment with lutein, zeaxanthin, DHA, lutein + zeaxanthin or lutein + zeaxanthin with DHA. The data showed H₂O₂ reduced cell viability and DHA content, while promoted catalase activity and certain oxidized PUFA products. Treatment with DHA enhanced omega-3 PUFA enzymatic oxidation namely, anti-inflammatory mediators such as hydroxy-DHA, resolvins and neuroprotection compared to control; the effects were not influenced by the carotenoids. Omega-6 PUFA oxidation, namely pro-inflammatory HETE (5-, 9-, 12 and 20-HETE), and isoprostanes (5- and 15-F_2t-IsoP and 4-F_3t-IsoP) were reduced by lutein + zeaxanthin while the addition of DHA did not further reduce these effects. We observed transcriptional regulation of 5-lipoxygenase by DHA and GPx1 and NEFEL2 by the carotenoids that potentially resulted in decreased HETEs and glutathione respectively. 4-HNE was not affected by the treatments but 4-HHE was reduced by lutein + zeaxanthin with and without DHA. To conclude, carotenoids and DHA appeared to regulate inflammatory lipid mediators while the carotenoids also showed benefits in reducing non-enzymatic oxidation of omega-6 PUFA.

Lutein reverses hyperglycemia-mediated blockage of Nrf2 translocation by modulating the activation of intracellular protein kinases in retinal pigment epithelial (ARPE-19) cells

Diabetic retinopathy (DR) is a major cause of acquired blindness among working adults. The retinal pigment epithelium (RPE), constitutes an outer blood-retinal barrier, is vastly affected in diabetic humans and animals. Lower levels of lutein in the serum and retina of diabetic population, and beneficial effects of carotenoids supplementation in diabetic retinopathy patients created an interest to examine the protective effect of lutein on hyperglycemia-mediated changes in oxidative stress and antioxidant defense system in ARPE-19 cells. The WST-1 assay was performed to analyze the impact of glucose, and lutein on the viability of ARPE-19. The intracellular oxidative stress was measured by a DCF (dichlorofluorescein) assay, mitochondrial membrane potential (MMP) was monitored using a JC-10 MMP assay kit and GSH level was examined using GSH/GSSG ratio detection kit. The oxidative stress markers, protein carbonyl and malondialdehyde were spectrophotometrically measured using 2,4-dinitrophenylhydrazine and 2-thiobarbituric acid, respectively. The expression of endogenous antioxidant enzymes and regulatory proteins in ARPE-19 was quantified by western blotting. The localization of Nrf2 protein was examined by immunofluorescent staining. The results show that lutein (up to 1.0 μM) did not affect the viability of ARPE-19 grown in both normal and high-glucose conditions. Lutein treatment blocked high glucose-mediated elevation of intracellular ROS, protein carbonyl and malondialdehyde content in ARPE-19 cells. The decreased MMP and GSH levels observed in ARPE-19 grown under high-glucose condition were rescued by lutein treatment. Further, lutein protected high glucose-mediated down-regulation of a redox-sensitive transcription factor, Nrf2, and antioxidant enzymes, SOD2, HO-1, and catalase. This protective effect of lutein was linked with activated nuclear translocation of Nrf2, which was associated with increased activation of regulatory proteins such as Erk and AKT. Our study indicates that improving the concentration of lutein in the retina could protect RPE from diabetes-associated damage.

Antioxidant, Antimutagenic and Cytoprotective Properties of Hydrosos Pistachio Nuts

Pistachio nuts are included among the foods with the highest antioxidant capacity. Stressed cultivating conditions, such as the use of regulated deficit irrigation (RDI), are expected to create a plant response that might increase the production of secondary metabolites. Fruits that are obtained under RDI treatments are commonly called hydroSOS products. The aim of this work was to study the influence of using different rootstocks (P. atlantica, P. integerrima, and P. terebinthus) and two RDI treatments on the antioxidant (ABTS, ferric reducing antioxidant power (FRAP), and DPPH), antimutagenic (Ames test), and cytotoxicity (MTT assay in five human cell lines) activities of pistachios. P. terebinthus showed the best antioxidant activity, and the RDI treatments maintained and improved the antioxidant properties of pistachios. Neither the rootstock nor the RDI had significant impact on the antimutagenic potential of pistachios. The nut extracts had no toxic effect on non-cancerous cells and the application of RDI did not reduce their cytoprotective capacity. Furthermore, neither rootstock nor RDI treatments affected the ability of the pistachio extracts of preventing the oxidative damage by H₂O₂. The application of RDI strategies, in addition to allowing irrigation water saving, led to obtaining pistachios with the same or even better biofunctional characteristics as compared to fully irrigated pistachios.

Protective effect of diphlorethohydroxycarmalol against oxidative stress-induced DNA damage and apoptosis in retinal pigment epithelial cells

Purpose: Reactive oxygen species (ROS) contribute to the onset and progression of disease pathogenesis in a variety of organs, including age-related macular degeneration (AMD). Diphlorethohydroxycarmalol (DPHC), a phlorotannin compound, is one of the major components of the brown alga Ishige okamurae Yendo, and has been shown to have strong antioxidant capacity. The purpose of this study was to evaluate the protective effects of DPHC against oxidative stress (hydrogen peroxide, H₂O₂)-induced DNA damage and apoptosis in cultured ARPE19 retinal pigment epithelial (RPE) cells. Materials and methods: Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay. Intracellular ROS generation was measured by flow cytometer using 2',7'-dichlorofluorescin diacetate. The magnitude of apoptosis was measured by flow cytometry using the annexin V/propidium iodide double staining. DNA damage was evaluated by DNA fragmentation assay, comet assay and 8-hydroxy-2'-deoxyguanosine (8-OHdG) analysis. To observe the mitochondrial membrane potential, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide staining was performed. In order to identify the underling mechanism of DPHC against H₂O₂-induced cellular alteration, we performed immune blotting. Results: The results of this study showed that the decreased survival rate brought about by H₂O₂ could be attributed to the induction of DNA damage and apoptosis accompanied by the increased production of ROS, which was remarkably reversed by DPHC. In addition, the loss of H₂O₂-induced mitochondrial membrane potential was significantly attenuated in the presence of DPHC. The inhibitory effect of DPHC on H₂O₂-induced apoptosis was associated with a reduced Bax/Bcl-2 ratio, the protection of the activation of caspase-9 and -3 and the inhibition of poly (ADP-ribose) polymerase cleavage, which was associated with the blockage of cytochrome c release to the cytoplasm. Conclusions: Our data proved that DPHC protects ARPE19 cells against H₂O₂-induced DNA damage and apoptosis by scavenging ROS and thus suppressing the mitochondrial-dependent apoptosis pathway. Therefore, this study suggests that DPHC has the therapeutic potential to prevent AMD by inhibiting oxidative stress-induced injury in RPE cells.

Protective effect of lutein on spinal cord ischemia-reperfusion injury in rats

OBJECTIVES

Paraplegia is deterioration in motor or sensory function of the lower limbs that can occur after modification of a thoracoabdominal aortic aneurysm. The purpose of this survey was to determine the protective action of lutein on spinal cord ischemia-reperfusion (I-R) damage.

MATERIALS AND METHODS

Thirty-five male rats were distributed into five groups: intact, sham, dimethyl sulfoxide (I-R+DMSO), low dose lutein (I-R+0.2 mg/kg lutein), and high dose lutein (I-R + 0.4 mg/kg lutein). Thirty minutes before surgery, a single dose lutein or DMSO was administered to rats of experimental groups. Next, the abdominal aorta was clamped exactly under the left renal artery and proximal to the abdominal aortic bifurcation for 60 min. All animals were evaluated by neurological function and histological and biochemical examinations at 72 hr after I-R.

RESULTS

The mean motor deficit index (MDI) scores in lutein groups were lower compared with the DMSO group (P<0.001). Plasma level of malondialdehyde in lutein groups decreased compared with the DMSO group (P<0.05). Plasma level of total antioxidative capacity was increased in the high lutein group compared with low dose lutein and sham groups (P<0.05). Mean number of normal motor neurons in lutein groups was greater compared with the DMSO group (P<0.001). There was a significant negative correlation between MDI scores and the number of normal neurons (r= -0.764, P<0.001).

CONCLUSION

Findings of the present study demonstrate that lutein may support spinal cord neurons from I-R damage.

Increasing protective activity of genistein by loading into transfersomes: A new potential adjuvant in the oxidative stress-related neurodegenerative diseases?

BACKGROUND

Genistein is a soy-derived isoflavone and phytoestrogen with antioxidant and neuroprotective activity. Genistein has intrinsically low oral bioavailability that affects its dose-response activities.

PURPOSE

Nanotechnologies were used to obtain the delivery of genistein to the brain: lipid-based nanovesicles, transfersomes, loaded with the phytoestrogen were developed as potential therapeutic or preventive strategy against neurodegenerative diseases by intranasal administration.

METHODS

Phosphatidylcholine from soybean and different edge activators were used to prepare transfersomes. The effect of selected nanovesicles on the oxidative damage was studied in PC12 cell line.

RESULTS

Suitable nanovesicles as carrier of genistein were obtained; their composition affects deformability, drug permeation behavior and cytotoxicity. In particular, the formulation containing Span 80, GEN-TF2, showed efficiency of internalization into the cell and it was able to attenuate ROS formation and to reduce the amount of apoptotic cells generated by H₂O₂ treatment compared to genistein.

CONCLUSION

GEN-TF2 was able to reduce the oxidative damage suggesting a possible antioxidant role of this drug delivery system. These obtained data confer to GEN-TF2 a potential antioxidant activity and then it could be used as adjuvant therapy in oxidative stress-related neurodegenerative diseases.

Genipin protects against H2O2-induced oxidative damage in retinal pigment epithelial cells by promoting Nrf2 signaling

Oxidative stress serves a vital function in the pathogenesis of age-related macular degeneration (AMD); genipin (GP) possesses antioxidative properties. The present study aimed to investigate the effects of GP on retinal pigment epithelial (RPE) cells induced by H₂O₂ and the underlying mechanism. ARPE-19 cells were subjected to H₂O₂ treatment to induce oxidative damage. Cell viability was determined via an MTT assay. Reactive oxygen species (ROS) levels and cell apoptosis were detected by flow cytometry. Nuclear factor-erythroid 2-related factor-2 (Nrf2) signaling-associated and the expression of apoptosis-associated factors were measured using reverse transcription-quantitative polymerase chain reaction assay and western blotting. The results revealed that 200 µM H₂O₂ and 30 µM GP were determined to be the optimal concentrations for subsequent experimentation. GP reversed the inhibitory effects of H₂O₂ by promoting cell viability, attenuating ROS accumulation and cell apoptosis, and increased the expression of Nrf2, heme oxygenase-1 (HO-1) and NAD(P)H: Quinine oxidoreductase 1 (NQO1); Nrf2 silencing inhibited HO-1 and NQO1 expression. In addition, Nrf2 silencing enhanced the effects of H₂O₂ by promoting ROS production and cell apoptosis. Compared with H₂O₂, Nrf2 silencing further decreased the expression levels of B-cell lymphoma-2 (Bcl-2), but increased that of Bcl-2-associated X protein and cleaved-caspase-3. The results of the present study revealed that Nrf2 silencing attenuated the protective effects of GP on H₂O₂-induced injury in ARPE-19 cells by promoting apoptosis and oxidation. Collectively, GP attenuated oxidative damage induced by H₂O₂ in ARPE-19 cells. Furthermore, the molecular mechanism may be associated with the Nrf2 signaling pathway. The findings of the present study nay provide insight into a potential therapeutic agent for the treatment of AMD.

Protection of Kaempferol on Oxidative Stress-Induced Retinal Pigment Epithelial Cell Damage

The protection of retinal pigment epithelium (RPE) injury plays an important role in the prevention of or in delaying the pathological progress of retinal degeneration diseases, like age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa. Oxidative stress has been identified as a major inducer of RPE injury, which eventually could lead to a loss of vision. Kaempferol is a natural flavonoid widely distributed in many edible plants, fruits, and traditional medicines and has been reported to have antioxidant, anti-inflammatory, anticancer, and antimicrobial activities. The present study demonstrates that the total antioxidant capacity of kaempferol is approximately two times stronger than that of lutein which is also a natural antioxidant that is widely used in the prevention or treatment of AMD. Our data indicates that kaempferol protects human RPE cells (ARPE-19) from hydrogen peroxide- (H₂O₂-) induced oxidative cell damage and apoptosis through the signaling pathways involving Bax/Bcl-2 and caspase-3 molecules proofed by real-time PCR and Western blot results. Kaempferol also inhibits the upregulated vascular endothelial growth factor (VEGF) mRNA expression levels induced by H₂O₂ in ARPE-19 cells and affects the oxidation and antioxidant imbalanced system in ARPE-19 cells treated by H₂O₂ through the regulations of both the activities of reactive oxygen species (ROS) and superoxide dismutase (SOD). Furthermore, our in vivo experimental results show that in sodium iodate-induced retinal degeneration rat model, kaempferol could protect sodium iodate-induced pathological changes of retina tissue and retinal cells apoptosis as well as the upregulated VEGF protein expression in RPE cells. In summary, these novel findings demonstrate that kaempferol could protect oxidative stressed-human RPE cell damage through its antioxidant activity and antiapoptosis function, suggesting that kaempferol has a potential role in the prevention and therapeutic treatment of AMD or other retinal diseases mediated by oxidative stress.

Effects of the Macular Carotenoid Lutein in Human Retinal Pigment Epithelial Cells

Retinal pigment epithelial (RPE) cells are central to retinal health and homoeostasis. Oxidative stress-induced damage to the RPE occurs as part of the pathogenesis of age-related macular degeneration and neovascular retinopathies (e.g., retinopathy of prematurity, diabetic retinopathy). The xanthophyll carotenoids, lutein and zeaxanthin, are selectively taken up by the RPE, preferentially accumulated in the human macula, and transferred to photoreceptors. These macular xanthophylls protect the macula (and the broader retina) via their antioxidant and photo-protective activities. This study was designed to investigate effects of various carotenoids (β-carotene, lycopene, and lutein) on RPE cells subjected to either hypoxia or oxidative stress, in order to determine if there is effect specificity for macular pigment carotenoids. Using human RPE-derived ARPE-19 cells as an in vitro model, we exposed RPE cells to various concentrations of the specific carotenoids, followed by either graded hypoxia or oxidative stress using tert-butyl hydroperoxide (tBHP). The results indicate that lutein and lycopene, but not β-carotene, inhibit cell growth in undifferentiated ARPE-19 cells. Moreover, cell viability was decreased under hypoxic conditions. Pre-incubation of ARPE-19 cells with lutein or lycopene protected against tBHP-induced cell loss and cell co-exposure of lutein or lycopene with tBHP essentially neutralized tBHP-dependent cell death at tBHP concentrations up to 500 μM. Our findings indicate that lutein and lycopene inhibit the growth of human RPE cells and protect the RPE against oxidative stress-induced cell loss. These findings contribute to the understanding of the protective mechanisms attributable to retinal xanthophylls in eye health and retinopathies.