Lactucaxanthin Regulates the Cascade of Retinal Oxidative Stress, Endoplasmic Reticulum Stress and Inflammatory Signaling in Diabetic Rats.

PURPOSE: The purpose of this study is to investigate the protective mechanism of lactucaxanthin against retinal angiogenesis in diabetic retinopathy. METHODS: Streptozotocin-induced diabetic rats were orally gavaged with either lactucaxanthin or lutein (n=12/group) for 8 weeks. Serum and retina collected from euthanized rats were subjected to assess oxidative stress, ER stress and inflammatory response. RESULTS: Lactucaxanthin administration was found to lower oxidative stress markers (protein carbonylation and lipid peroxidation) by augmenting antioxidant activity expression and ameliorated VEGF-A levels in diabetic group. Likewise, it suppressed the expression of ER stress (ATF4, ATF6, and XBP1), and inflammatory (TNF-α, IL-6, NF-κB, and ICAM-1) markers in diabetic retina. In addition, lactucaxanthin improved glucose tolerance and lipid profile under diabetic condition and suppressed the crosstalk between OS, ER stress, and inflammation. CONCLUSION: Lactucaxanthin could be used as a promising therapeutic bioactive for treating DR condition, and retinal angiogenesis. EXPERT OPINION: Limitation of the study includes the sample size and the duration of treatment. Despite these limitations, this study has revealed the potential of lactucaxanthin in treating eye related diabetic complications. To validate the results obtained from this study, clinical study must be performed to understand the relative benefit of lactucaxanthin in DR treatment.

Lutein ameliorates high-fat diet-induced obesity, fatty liver, and glucose intolerance in C57BL/6J mice.

Obesity is a multi-factorial metabolic syndrome that increases the risk of cardiovascular diseases, diabetes, and cancer. We recently demonstrated the antiadipogenic efficacy of lutein using a 3 T3-L1 cell culture model. This study aimed to examine the antiobesity efficacy of lutein on high-fat (60% kcal fat) diet-induced C57BL/6J obese mice model. Lutein (300 and 500 µM), Orlistat (30 mg/kg body weight - positive control), and its combination (orlistat, 15 mg/kg body weight+lutein, 300 µM) were administered in high-fat diet (HFD)-fed mice every other day for 24 weeks. The effect on serum and hepatic lipid parameters was estimated using biochemical assay kits. The adipose tissue expression of adipocyte differentiation markers at gene and protein levels was analyzed by RT-PCR and western blotting, respectively. The results showed that lutein administration and drug significantly reduced epididymal and abdominal adipose tissue weights. Further, lutein reduced the serum cholesterol and LDL-C concentration compared to the HFD group. The HFD-induced elevation in the hepatic triglycerides and cholesterol levels were significantly blocked by lutein and its combination with the drug. Similarly, lutein and its drug combination efficiently lowered the HFD-mediated elevated blood glucose levels. Lutein downregulated the expression of CEBP-α, PPAR-γ, and FAS in the epididymal adipose tissue. Thus, supplementation of lutein may control diet-induced obesity and associated complications in the human population.

Effective inhibition of adipogenesis-mediated inflammation by a macular carotenoid, lutein in vitro.

An absolute interlinks between inflammation and obesity with scarce investigations on the role of lutein in inflammation-induced obesity motivated us to explore the protective mechanism of lutein on adipogenesis-mediated inflammation in vitro by culturing RAW264.7 macrophages in adipocyte conditioned medium. The RAW264 macrophage cells were cultured with adipocyte-conditioned media, and the potency of lutein on the expression of adipocyte inflammation-associated protein markers (IL-1ß, MCP-1, TNF-α, IL-6, NF-κB, and IKKα/ß) were analyzed by western blotting. The data revealed that lutein effectively reduces the protein levels of major inflammatory markers such as NF-κB, IL-1ß, MCP-1, and TNF-α in differentiated adipocytes. Interestingly, lutein hampered inflammation in the RAW264 cells that were cultured in adipocyte-conditioned media by lowering the protein expression of IL-1ß, MCP-1, and TNF-α. The blockage of inflammation by lutein in both differentiated adipocytes, and adipogenesis-induced macrophages is associated with suppression of IKK α/ß phosphorylation. These data suggest that lutein potentially alters adipocyte differentiation-mediated inflammation by regulating the NF-κB signaling pathway. Thus, lutein could be utilized as a potent nutraceutical agent in the management of obesity and associated inflammation. PRACTICAL APPLICATIONS: Lutein isolated from a dietary source exhibited an inhibitory effect in adipogenesis-induced inflammations. The findings of this study authenticate the diversified prospective of lutein in regulating obesity and other inflammation-related diseases. Thus, it is understood that continuous intake of lutein-rich food or dietary intervention of lutein may reduce the risk of developing obesity.

Inhibitory efficacy of lutein on adipogenesis is associated with blockage of early phase regulators of adipocyte differentiation.

A comprehensive molecular mechanistic role of lutein on adipogenesis is not well understood. The present study focused to evaluate the effect of lutein at the early and late phase of adipocyte differentiation in vitro using a 3T3-L1 cell model. The effect of purified carotenoid on the viability of normal and differentiated 3T3-L1 cells was analyzed by WST-1 assay. Oil Red O and Nile red staining were employed to observe lipid droplets in mature adipocytes. The effect of lutein on gene and protein expression of major transcription factors and adipogenic markers was analyzed by RT-PCR and western blotting, respectively. The role of lutein on mitotic clonal expansion was analyzed by flow cytometry. The results showed a significant reduction (p < 0.05) in the accumulation of lipid droplets in lutein-treated (5 µM) cells. Inhibition in lipid accumulation was associated with down-regulated expression of CEBP-α and PPAR-γ at gene and protein levels. Subsequently, lutein repressed gene expression of FAS, FABP4, and SCD1 in mature adipocytes. Interestingly, it blocks the protein expression of CEBP-α and PPAR-γ in the initial stages of adipocyte differentiation. This early-stage inhibition of adipocyte differentiation is linked with repressed phosphorylation AKT and ERK. Further, upregulated cyclin D and down-regulated CDK4 and CDK2 in lutein treated adipocytes enumerate its role in delaying the cell cycle progression at the G0/G1 phase. Our results emphasize that adipogenesis inhibitory efficacy of lutein is potentiated by halting early phase regulators of adipocyte differentiation, which strengthens the competency of lutein besides its inevitable presence in the human body.

A critical review on anti-angiogenic property of phytochemicals.

Angiogenesis, a process involved in neovascularization, has been found to be associated with several metabolic diseases like cancer, retinopathy etc. Thus, currently, the focus on anti-angiogenic therapy for treatment and prevention of diseases has gained significant attention. Currently available Food and Drug Administration (FDA) approved drugs are targeting either vascular endothelial growth factor or it's receptor, but in the long term, these approaches were shown to cause several side effects and the chances of developing resistance to these drugs is also high. Therefore, identification of safe and cost-effective anti-angiogenic molecules is highly imperative. Over the past decades, dietary based natural compounds have been studied for their anti-angiogenic potential which provided avenues in improving the angiogenesis based therapy. In this review, major emphasis is given to the molecular mechanism behind anti-angiogenic effect of natural compounds from dietary sources.

Enhanced phosphorylation of AMPK by lutein and oxidised lutein that lead to mitochondrial biogenesis in hyperglycemic HepG2 cells.

The stimulation of adenosine monophosphate-activated protein kinase (AMPK) is a prime target to decrease the hyperglycemic condition, hence it is a lutein (L) and oxidised lutein (OXL) is a target molecule for the treatment of type II diabetes. In the current study, a plausible interaction of L and OXL with AMPK was investigated by molecular docking. In addition, the effect of L and OXL for the activation of AMPK that triggers the downstream regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), TFAM expression, mitochondrial DNA (mtDNA), mitochondrial biogenesis and superoxide dismutase 2 (SOD2) in high glucose treated HepG2 cells were investigated by quantitative polymerase chain reaction and Western blot analysis. Molecular docking reveals higher binding affinity of L (ΔG = -6.3 kcal/mol) and OXL (ΔG = -15.5 kcal/mol) with AMPK, compared with metformin (ΔG = -5.0 kcal/mol). The phosphorylation of AMPK increased by 1.3- and 1.5-fold with L and OXL treatment, respectively, in high glucose induced HepG2 cells. The activation of PGC-1α is significant (P < 0.05) in OXL group than L. Similarly, TFAM expression is increased with L and OXL compared with the high glucose group. Further increase in SOD2 and mtDNA, confirms the efficacy of L and OXL in restoring the mitochondrial biogenesis in high glucose induced cells through AMPK, PGC-1α, and TFAM.

Fatty acids modulate the efficacy of lutein in cataract prevention: Assessment of oxidative and inflammatory parameters in rats.

BACKGROUND: Effects of lutein (L) and fatty acids [linoleic acid (LA), eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA) and oleic acid (OA)] on oxidative stress and inflammation in cataract were assessed. METHODS: Cataract was induced in male Wistar rat pups (11 days old) by giving a single dose of sodium selenite (25 µM/kg body weight) by IP. Lutein (1.3 µmol/kg body weight) was given one day before and five days after selenite injection as a micelle with 7.5 mM LA, or 7.5 mM EPA + DHA or 7.5 mM OA. Serum and lens oxidative stress and inflammatory parameters having a bearing cataract were assessed. RESULTS: Serum and lens nitric oxide, MDA and protein carbonyls were significantly (p < 0.05) increased in cataract compared to control and experimental groups. Catalase, SOD, glutathione peroxidase and glutathione transferase activity and glutathione level in serum and lens of cataract group were significantly (p < 0.05) decreased. Serum eicosanoids (PGE2, LTB4, and LTC4) and cytokines (CRP, TNF-α, IL1-ß, and MCP-1) were significantly (p < 0.05) increased in cataract. The activity of cPLA2 and Cox-2 in cataract lens was higher (p < 0.05) compared to other groups. EP-1, NOS-2 and NF-kB expression were higher (p < 0.05) in cataract. The ratio of water insoluble to water soluble protein was increased in cataract lens. Group administered with L + EPA + DHA exhibited highest cataract prevention compared to L + LA and L + OA. Pups given lutein with EPA + DHA had the highest amount of lutein in the lens. CONCLUSIONS: The anti-cataract activity of lutein was influenced by fatty acids and found to be highest with EPA + DHA compared to LA or OA.

Lutein derived fragments exhibit higher antioxidant and anti-inflammatory properties than lutein in lipopolysaccharide induced inflammation in rats.

In the present study, we appraise the anti-inflammatory efficacy of lutein oxidative degradation derivatives mediated through UV-irradiation over lutein in counteracting the inflammation induced by lipopolysaccharide (LPS) in rats (n = 5 per group). UV-irradiated lutein fragments were identified as anhydrolutein (B, C40H54O), 2,6,6-trimethylcyclohexa-1,4-dienylium (M1, C9H13), (2E,4E,6E,8E)-9-(4-hydroxy-2,6,6-trimethylcyclohex-1-1en-1-yl)-3,7-dimethylnona-2,4,6,8-tetraen-1-ylium (M2, C20H29O), 4-[(1E,3E,5E,7E)-3,7,-dimethyldeca-1,3,5,7-tetraen-1-yl]-3,5,5-methylcyclohex-3-en-1-ol (M3, C21H30O) and zeaxanthin (M4, C40H56O) and its isomers as 13'-Z zeaxanthin, 13'-Z lutein, all-trans zeaxanthin, and 9-Z lutein. Induction of inflammation by LPS significantly increased the production of nitrites (3.3 fold in the serum and 2.6 fold in the liver), prostaglandin E2 (26 fold in the serum), and pro-inflammatory cytokines like tumor necrosis factor-α (6.6 fold in the serum), and interleukin-6 (4.8 fold in the serum). Oxidative derivatives of lutein, especially M1, M2 and M3, ameliorated acute inflammation in rats by inhibiting the production of nitrites, malondialdehyde (MDA), PGE2, TNF-α, and IL-6 cytokines more efficiently than lutein in rats. The anti-inflammatory mechanism of derivatives might be related to the decrease of inflammatory cytokines and the increase of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione S transferase, glutathione reductase), which would result in the reduction of iNOS, COX-2 and MDA and subsequently inflammatory responses.

Risk Factors for Nuclear and Cortical Cataracts: A Hospital Based Study.

PURPOSE: To evaluate risk factors associated with nuclear and cortical cataracts among a hospital based sample of subjects in Southern India. METHODS: In this hospital-based study, 3,549 subjects including 2,090 male and 1,459 female individuals aged 45 years and over were randomly screened for nuclear and cortical cataracts. Lens opacity was graded and classified after pupil dilation using the lens opacities classification system (LOCS) III at the slit lamp. Furthermore, participants were interviewed for lifestyle variables and dietary intake of carotenoids using a structured food frequency questionnaire. RESULTS: Demographic risk factors for cataracts included older age and lower socioeconomic status. Nuclear cataracts were associated with diabetes (OR = 6.34; 95% CI: 2.34-8.92%), tobacco chewing (moderate, OR = 3.04; heavy, OR = 4.62), cigarette smoking (moderate, OR = 1.58; heavy, OR = 1.87) and hypertension (OR = 1.56; 95% CI: 1.25-2.78%). Cortical cataracts were associated with diabetes (OR = 15.03; 95% CI: 7.72-29.2%), tobacco chewing (moderate, OR = 2.16; heavy, OR = 2.32) and cigarette smoking (moderate, OR = 2.20; heavy, OR = 2.97). Higher dietary intake of lutein/zeaxanthin (L/Z) and ß-carotene was associated (P < 0.001) with a lower risk of nuclear and cortical cataracts. CONCLUSION: Higher dietary intake of carotenoids is associated with a lower risk of cataracts. Nuclear and cortical cataracts are associated with various risk factors such as diabetes, hypertension, cigarette smoking and tobacco, similar to studies conducted in other Asian and European populations, irrespective of ethnic origin.

Dietary and lifestyle risk factors associated with age-related macular degeneration: a hospital based study.

AIM: To establish the frequency, associations and risk factors for age-related macular degeneration (AMD) in hospital population of South India. MATERIALS AND METHODS: In this cross-sectional hospital based study, 3549 subjects (2090 men and 1459 women) above 45 years of age were screened randomly for AMD. Participants underwent ocular evaluation and were interviewed for lifestyle variables and dietary intake of carotenoids by structured food frequency questionnaire. AMD was defined according to the international classifications and grading system. RESULTS: Either form of AMD was detected in 77 (2.2%) participants. Of which, early and late AMD was present in 63 (1.8%) and 14 (0.4%) subjects, respectively. Binary logistic analysis showed that the incidence of AMD was significantly higher with increasing age (Odds ratio [OR] 1.17; 95% CI 1.13-1.22) and diabetes (OR 3.97; 95% CI 2.11-7.46). However, AMD was significant among heavy cigarette smokers (OR 5.58; 95% CI 0.88-7.51) and alcoholics (OR 4.85; 95% CI 2.45-12.22). Dietary lutein/zeaxanthin (L/Z) and ß-carotene intake were associated (P < 0.001) with the reduction in risk for AMD, with an OR of 0.38 and 0.65, respectively. CONCLUSIONS: Higher dietary intake of carotenoids, especially L/Z, was associated with lower risk for AMD. Risk of AMD is higher with increasing age and was prevalent among subjects with diabetes. Cessation of smoking and alcohol may reduce the risk of AMD in this population.

Fucoxanthin restrains oxidative stress induced by retinol deficiency through modulation of Na(+)K(+)-ATPase [corrected] and antioxidant enzyme activities in rats.

BACKGROUND: Retinol deficiency is a major public health problem world wide, affecting children and women, in particular. It causes a variety of disorders in the body affecting various cellular functions. AIM OF THE STUDY: To study the effect of fucoxanthin (FUCO), a non-provitamin-A carotenoid in comparison with retinol (ROH) on changes in antioxidant molecules, lipid peroxidation and membrane bound enzymes in tissue and microsomes, induced by ROH deficiency in rats. METHODS: After induction of ROH deficiency by feeding a diet devoid of ROH for 8 weeks, rats were divided into two groups (n = 20/group) and administered orally a dose of either FUCO (0.83 micromol) or ROH (0.87 micromol). A group of ROH deficient rats (n = 5) and rats (n = 5) fed with ROH sufficient diet was considered as baseline and control groups respectively. Over a period of 8 h, activity of catalase (CAT), glutathione transferase (GST), level of lipid peroxidation (LPx), fatty acids in plasma, liver and liver microsomes and activity of Na(+)K(+)-ATPase in liver microsomes were evaluated. RESULTS: ROH restriction increased LPx (P < 0.05) in liver (~19%) and plasma (~34%) while the activities of CAT (90 +/- 1%) and GST (17 +/- 4%) decreased compared to control. Significant elevation (91%) was observed for Na(+)K(+)-ATPase activity in liver microsomes of ROH deficient when compared to control group and levels were lowered on administration of ROH (37-69%) and FUCO (51-57%), towards control over a period of 8 h. ROH and FUCO suppressed (P < 0.05) the LPx level (%) in plasma (34-62, 7-85), liver homogenate (9-71, 24-72) and liver microsomes (83-92, 61-87), while the activities of CAT in plasma (89-97%, 91-95%) and liver microsomes (84-93%, 85-93%) and GST in liver homogenate (43-53%, 44-51%) and liver microsomes (36-52%, 22-51%) were increased (P < 0.05) compared to ROH deficient group. CONCLUSIONS: Results show that FUCO, a non-provitamin-A carotenoid protects cell membrane by modulating Na(+)K(+)-ATPase (51-57% lowering) and the activities of CAT and GST at the tissue and microsomal level which are affected by ROH deficiency. This may be due to its antioxidant nature. These in turn reduce LPx caused by ROH deficiency.