An epoxide-furanoid rearrangement of spinach neoxanthin occurs in the gastrointestinal tract of mice and in vitro: formation and cytostatic activity of neochrome stereoisomers

A Novel Phytocolorant, Neoxanthin, as a Potent Chemopreventive: Current Progress and Future Prospects

Cancer is a general term for a group of similar diseases. It is a combined process that results from an accumulation of abnormalities at different biological levels, which involves changes at both genetic and biochemical levels in the cells. Several modifiable risk factors for each type of cancer include heredity, age, and institutional screening guidelines, including colonoscopy, mammograms, prostate-specific antigen testing, etc., which an individual cannot modify. Although a wide range of resources is available for cancer drugs and developmental studies, the cases are supposed to increase by about 70% in the next two decades due to environmental factors commonly driven by the way of living. The drugs used in cancer prevention are not entirely safe, have potential side effects and are generally unsuitable owing to substantial monetary costs. Interventions during the initiation and progression of cancer can prevent, diminish, or stop the transformation of healthy cells on the way to malignancy. Diet modifications are one of the most promising lifestyle changes that can decrease the threat of cancer development by nearly 40%. Neoxanthin is a xanthophyll pigment found in many microalgae and macroalgae, having significant anti-cancer, antioxidant and chemo-preventive activity. In this review, we have focused on the anti-cancer activity of neoxanthin on different cell lines and its cancer-preventive activity concerning obesity and oxidative stress. In addition to this, the preclinical studies and future perspectives are also discussed in this review.

Neoxanthin is undetectable in human blood after ingestion of fresh young spinach leaf

In a previous study, we demonstrated that the carotenoid neoxanthin was contained in young leafy vegetables including spinach and showed a fat accumulation inhibitory effect in vitro. To evaluate the bioavailability of neoxanthin, a raw young spinach leaf (100 g day-1 for 4 weeks) intake test was performed on 14 participants (36.5 ± 8.0 years; male:female ratio = 9:5). Neoxanthin, neochrome, β-carotene, and lutein concentration in the spinach and blood of participants (before and after the test) was measured using high performance liquid chromatography. Neither neoxanthin nor neochrome was detected in the blood samples, whereas β-carotene and lutein concentration significantly increased (1.4- and 1.9-fold, respectively) during testing. Neoxanthin bioavailability in humans is low; thus, it is unlikely to have a fat accumulation inhibitory effect in vivo, contrary to the result in vitro. Ingesting the leafy vegetables raw can help maintain high neoxanthin levels, but it is not beneficial for neoxanthin bioavailability.

Neoxanthin in young vegetable leaves prevents fat accumulation in differentiated adipocytes

The present study aimed to investigate the effect of young leaves on fat accumulation in differentiated 3T3-L1 adipocytes. A potent preventive effect on fat accumulation was observed in fractions of young leaves of spinach, beet, and arugula extracted with a low-polarity solvent (hexane:acetone:ethanol:toluene = 10:6:7:6). This effect was seemingly associated with the leaf carotenoid content, including lutein, β-carotene, and neoxanthin. Among these, only neoxanthin, with the characteristic structure of 5,6-monoepoxide and an allenic bond, significantly prevented fat accumulation in a dose-dependent manner. The preventive effect and carotenoid content, including neoxanthin, of these young leaves did not differ from those of the corresponding adult leaves. Therefore, our study demonstrated that young vegetable leaves, such as spinach, beet, and arugula leaves, contained neoxanthin, which prevented fat accumulation in adipocytes in vitro. In the future, the effectiveness of such young leaves and neoxanthin should be investigated in vivo.

Bioaccessibility of microalgae-based carotenoids and their association with the lipid matrix

The composition of microalgae can contribute to nutritious and functional diets. Among the functional compounds, carotenoids are in focus since positive effects on human health have been established, which are in turn related to their bioaccessibility. In addition to essential nutrients, our hypothesis was that microalgae biomasses could be used as sources of bioaccessible carotenoids. Thus, this study determined for the first time the bioaccessibility of carotenoids from biomass of Scenedesmus bijuga and Chlorella sorokiniana and their possible relationship with the lipid composition of the matrix. The samples were submitted to in vitro digestion protocol, and carotenoids were determined by HPLC-PDA-MS/MS. Individual bioaccessibility of carotenoids was ≥ 3.25%. In general, compounds in their cis conformation were more bioaccessible than trans; and total carotenes more than total xanthophylls. Twelve compounds were bioaccessible from the biomass of S. bijuga, and eight in C. sorokiniana. In S. bijuga, the bioaccessibility of total carotenoids was 7.30%, and the major bioaccessible carotenoids were 9-cis-β-carotene (43.78%), 9-cis-zeaxanthin (42.30%) followed by 9-cis-lutein (26.73%); while in C. sorokiniana, the total bioaccessibility was 8.03%, and 9-cis-β-carotene (26.18%), all-trans-β-carotene (13.56%), followed by 13-cis-lutein (10.71%) were the major compounds. Overall, the total content of lipids does not influence the bioaccessibility of total carotenoids. Still, the lipid composition, including structural characteristics such as degree of saturation and chain length of the fatty acid, impacts the promotion of individual bioaccessibility of carotenes and xanthophylls of microalgae. Finally, the results of this study can assist the development of microalgae-based functional food ingredients and products.

Mangifera indica Extracts as Novel PKM2 Inhibitors for Treatment of Triple Negative Breast Cancer

Pyruvate kinase (PK), a key enzyme that determines glycolytic activity, has been known to support the metabolic phenotype of tumor cells, and specific pyruvate kinase isoform M2 (PKM2) has been reported to fulfill divergent biosynthetic and energetic requirements of cancerous cells. PKM2 is overexpressed in several cancer types and is an emerging drug target for cancer during recent years. Therefore, this study was carried out to identify PKM2 inhibitors from natural products for cancer treatment. Based on the objectives of this study, firstly, plant extract library was established. In order to purify protein for the establishment of enzymatic assay system, pET-28a-HmPKM2 plasmid was transformed to E. coli BL21 (DE3) cells for protein expression and purification. After the validation of enzymatic assay system, plant extract library was screened for the identification of inhibitors of PKM2 protein. Out of 51 plant extracts screened, four extracts Mangifera indica (leaf, seed, and bark) and Bombex ceiba bark extracts were found to be inhibitors of PKM2. In the current study, M. indica (leaf, seed, and bark) extracts were further evaluated dose dependently against PKM2. These extracts showed different degrees of concentration-dependent inhibition against PKM2 at 90-360 μg/ml concentrations. We have also investigated the anticancer potential of these extracts against MDA-MB231 cells and generated dose-response curves for the evaluation of IC50 values. M. indica (bark and seed) extracts significantly halted the growth of MDA-MB231 cells with IC50 values of 108 μg/ml and 33 μg/ml, respectively. Literature-based phytochemical analysis of M. indica was carried out, and M. indica-derived 94 compounds were docked against three binding sites of PKM2 for the identification of PKM2 inhibitors. The results of in silico based screening have unveiled various PKM2 modulators; however, further studies are recommended to validate their PKM2 inhibitory potential via in vitro biochemical assay. The results of this study provide novel findings for possible mechanism of action of M. indica (bark and seed) extracts against TNBC via PKM2 inhibition suggesting that M. indica might be of therapeutic interest for the treatment of TNBC.

From carotenoid intake to carotenoid blood and tissue concentrations - implications for dietary intake recommendations

There is uncertainty regarding carotenoid intake recommendations, because positive and negative health effects have been found or are correlated with carotenoid intake and tissue levels (including blood, adipose tissue, and the macula), depending on the type of study (epidemiological vs intervention), the dose (physiological vs supraphysiological) and the matrix (foods vs supplements, isolated or used in combination). All these factors, combined with interindividual response variations (eg, depending on age, sex, disease state, genetic makeup), make the relationship between carotenoid intake and their blood/tissue concentrations often unclear and highly variable. Although blood total carotenoid concentrations <1000 nmol/L have been related to increased chronic disease risk, no dietary reference intakes (DRIs) exist. Although high total plasma/serum carotenoid concentrations of up to 7500 nmol/L are achievable after supplementation, a plateauing effect for higher doses and prolonged intake is apparent. In this review and position paper, the current knowledge on carotenoids in serum/plasma and tissues and their relationship to dietary intake and health status is summarized with the aim of proposing suggestions for a "normal," safe, and desirable range of concentrations that presumably are beneficial for health. Existing recommendations are likewise evaluated and practical dietary suggestions are included.

Assessment of carotenoid concentrations in red peppers (Capsicum annuum) under domestic refrigeration for three weeks as determined by HPLC-DAD

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Nine carotenoids, including phytoene and phytofluene, quantified in red pepper.

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Carotenoid concentrations did not vary significatively after 21 days under refrigeration.

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The most abundant carotenoids in Lamuyo-peppers were capsanthin, β-carotene, lutein and zeaxanthin.

Red peppers (Capsicum annuum) are rich in carotenoids and are widely grown and consumed all over the world. Today’s consumption patterns are characterized by periodical purchases of food and longer food storage periods, including raw fruits and vegetables, which could have a negative effect on healthy components. This study aims to investigate the individual carotenoid content in Lamuyo-variety red peppers in cool storage (7 °C) for three weeks. Carotenoid concentrations expressed in µg/100g of the edible portion were; lutein (1203), zeaxanthin (853), α-carotene (272), β-carotene (2167), β-cryptoxanthin (525), violaxanthin (770), capsanthin (9667), phytoene (348) and phytofluene (143). Carotenoid concentrations did not significantly vary after 21 days under household refrigeration conditions and thus the nutritional supply of provitamin A carotenoids and of carotenoids with eye health benefits such as lutein and zeaxanthin, as well as others with potential health benefits in humans such as capsanthin, violaxathin, phytoene and phytofluene.

Impact of Different Pasteurization Techniques and Subsequent Ultrasonication on the In Vitro Bioaccessibility of Carotenoids in Valencia Orange (Citrus sinensis (L.) Osbeck) Juice

The effects of traditional pasteurization (low pasteurization, conventional pasteurization, hot filling) and alternative pasteurization (pulsed electric fields, high pressure processing), followed by ultrasonication on the carotenoid content, carotenoid profile, and on the in vitro carotenoid bioaccessibility of orange juice were investigated. There was no significant difference in the total carotenoid content between the untreated juice (879.74 µg/100 g juice) and all pasteurized juices. Significantly lower contents of violaxanthin esters were found in the high thermally-treated juices (conventional pasteurization, hot filling) compared to the untreated juice, owing to heat-induced epoxy-furanoid rearrangement. The additional ultrasonication had almost no effects on the carotenoid content and profile of the orange juices. However, the in vitro solubilization and the micellarization efficiency were strongly increased by ultrasound, the latter by approximately 85.3-159.5%. Therefore, among the applied processing techniques, ultrasonication might be a promising technology to enhance the in vitro bioaccessibility of carotenoids and, thus, the nutritional value of orange juice.

Use of spinach powder as functional ingredient in the manufacture of UF-Soft cheese

Spinach fine powder is a good source of protein, fiber, antioxidant, and minerals, making it a suitable ingredient to be used in the formulation of foods with high nutritional or biological values. In the current study, spinach nano-powder (0.50, 1.00, 1.50, and 2%) was used in the manufacturing of ultra-filtered soft chesses (UF-soft chesses). The quality of the cheeses was assessed by measuring their chemical compositions, colors, sensory, and antioxidant properties. Dynamic light scattering (DLS) showed that particles of spinach powder followed a normal distribution pattern with an average diameter of about 328 nm. By increasing the addition of spinach nano-powder with retentate its content of fiber, minerals, total phenolic content, and antioxidant activity was improved. Moreover, the total solid, protein and acidity contents increased significantly with the increased percentage of added spinach nano-powder reaching maximum values after four weeks of cold storage. Cheese containing 0.5% and 1% spinach powder demonstrated higher values for sensory parameters than other treatments. UF-cheese prepared in this work represents a novel functional dairy product that can potentially provide the human body with better nutrients.

Gene Expression Profiling Analysis Reveals Putative Phytochemotherapeutic Target for Castration-Resistant Prostate Cancer

Prostate cancer is the leading cause of cancer death among men globally, with castration development resistant contributing significantly to treatment failure and death. By analyzing the differentially expressed genes between castration-induced regression nadir and castration-resistant regrowth of the prostate, we identified soluble guanylate cyclase 1 subunit alpha as biologically significant to driving castration-resistant prostate cancer. A virtual screening of the modeled protein against 242 experimentally-validated anti-prostate cancer phytochemicals revealed potential drug inhibitors. Although, the identified four non-synonymous somatic point mutations of the human soluble guanylate cyclase 1 gene could alter its form and ligand binding ability, our analysis identified compounds that could effectively inhibit the mutants together with wild-type. Of the identified phytochemicals, (8′R)-neochrome and (8′S)-neochrome derived from the Spinach (Spinacia oleracea) showed the highest binding energies against the wild and mutant proteins. Our results identified the neochromes and other phytochemicals as leads in pharmacotherapy and as nutraceuticals in management and prevention of castration-resistance prostate cancers.

Biomarkers of carotenoid bioavailability

The use of biomarkers constitutes an essential tool to assess the bioavailability of carotenoids in humans. The present article aims to review several methodological, host-related and modulating factors relevant on assessing and interpreting carotenoid bioavailability. Markers for carotenoid bioavailability can be broadly divided into direct, biochemical or "analytical" markers and indirect, physiological or "functional" indicators. Analytical markers usually refer to biochemical indicators of intake and/or status (short and long term exposure) while functional measures may be interpreted in terms of cumulative exposure, biological effect (bioactivity) or modification of risk factors. Both types of markers display advantages and limitations but, in general, a relationship exists among the type of marker, the biological specimen needed and the time required for a change. Humans may absorb a wide range of carotenes and xanthophylls and many of them may be found in serum and tissues. However, under physiological conditions, the several classes of dietary carotenoids may behave unequally leading to a different systemic profile and, moreover, they can be selectively accumulated at target tissues. In addition, some carotenoids may be chemically and enzymatically modified generating different oxidative metabolites and apocarotenoids. Quantitatively, the biological response upon carotenoid intervention (assessed by analytical and functional markers) is highly variable but the use of large doses and long-term protocols may lead to saturation effects and the loss of linearity in the response. Also, despite carotenoid exposition is considered to be safe, markers of overexposure include clinical signs (i.e. carotenodermia, corneal rings and retinopathy) and biochemical indicators (hypercarotenemia, xanthophyll esters). Overall, both host-related and methodological factors may influence analytical and functional markers to assess carotenoid bioavailability although the different subclasses of carotenoids may not be equally affected.

Generic characterization of apolar metabolites in red chili peppers (Capsicum frutescens L.) by orbitrap mass spectrometry

The aim of the present study was to develop a generic analytical method for the identification and quantitation of apolar plant metabolites in biomass using liquid chromatography-photodiode array-accurate mass mass spectrometry (LC-PDA-amMS). During this study, a single generic sample preparation protocol was applied to extract apolar plant metabolites. Compound identification was performed using a single generic screening method for apolar compounds without the need for dedicated fractionation. Such a generic approach renders vast amounts of information and is virtually limited by only the solubility and detector response of the metabolites of interest. Method validation confirmed that this approach is applicable for quantitative purposes. Furthermore, an identification-quantitation strategy based on amMS and molar extinction coefficients was used for carotenoids, eliminating the need for reference standards for each carotenoid. To challenge the validated method, chili peppers (Capsicum frutescens L.) were analyzed to unravel their complex phytochemical composition (carotenoids, glycolipids, glycerolipids, capsaicinoids, lipid-soluble vitamins).

Determination of fucoxanthin isomers in microalgae (Isochrysis sp.) by high-performance liquid chromatography coupled with diode-array detector multistage mass spectrometry coupled with positive electrospray ionization

RATIONALE

Due to their health benefits, there is growing interest in the production and use of carotenoids from natural sources, e.g. microalgae. To date, only Haematococcus pluvialis and Dunaliella, that accumulate, respectively, astaxanthin and β-carotene in large quantities, are grown commercially. However, interest is also being focused on other xanthophylls, such as (all-E)-fucoxanthin characterized by anti-obesity and anti-carcinogenic effects. In this regard, rigorous chemical and analytical techniques following preparative isolation of components are needed to unequivocally identify individual carotenoids in microalgae.

METHODS

The carotenoid profile of Isochrysis sp. biomass, produced in closed photobioreactors, was determined by reversed-phase C30 (RP-30) high-performance liquid chromatography coupled with diode-array detector mass spectrometry using positive electrospray ionization (HPLC/DAD-MS/ESI(+) ) analysis. Additionally, multistage mass spectrometry (MS(n) ) analyses, together with fine structures of the UV-vis spectra, were used to differentiate structural and geometrical isomers.

RESULTS

This technique allowed the simultaneous determination of geometrical, isomers of fucoxanthin (all-E-fucoxanthin, 13Z-, 13'Z- and 9'Z-fucoxanthin), diatoxanthin and 5,8-epoxydiadinoxanthin diasteroisomers (R/S). The analyzed extracts contained fucoxanthin isomers as the major carotenoids and, in particular, (all-E)-fucoxanthin was the main geometrical isomer (~85%) found at a concentration of 17 mg/g of the lyophilized biomass.

CONCLUSIONS

Considering the high content of fucoxanthin in Isochrysis sp. biomass, the microalga could be proposed as a source of this compound for nutraceutical and pharmaceutical applications.

Carotenoid content of wild edible young shoots traditionally consumed in Spain (Asparagus acutifolius L., Humulus lupulus L., Bryonia dioica Jacq. and Tamus communis L.)

BACKGROUND

Wild vegetables have traditionally been consumed as part of the Mediterranean diet, being valuable sources of nutrients and bioactive compounds. The objective of this work was to analyse the carotenoid content of the edible young shoots of four species (Asparagus acutifolius L., Humulus lupulus L., Bryonia dioica Jacq. and Tamus communis L.) as part of a wider study on the characterisation of the nutritional composition of wild edible plants commonly consumed in Spain. Samples were gathered from two locations in Central Spain for two consecutive years.

RESULTS

Lutein, β-carotene, neoxanthin and violaxanthin were quantified by high-performance liquid chromatography with a photodiode array detector. Median concentration ranges (μg g(-1) edible wet weight) were: β-carotene, 3.39-6.69, lutein, 5.44–19.13;neoxanthin, 5.17-17.37; and violaxanthin, 2.08-8.93. The highest carotenoid content was that of B. dioica (59.01 μg g(-1)) and the lowest was found in A. acutifolius (17.58 μg g(-1)) [corrected].

CONCLUSION

Our results show that these wild young shoots are richer sources of carotenoids than many of the commercially available leafy vegetables.

Effect of the interaction of heat-processing style and fat type on the micellarization of lipid-soluble pigments from green and red pungent peppers (Capsicum annuum)

The high diversity of carotenoids and chlorophylls in foods contrasts with the reduced number of pigments that typically are investigated in micellarization studies. In this study, pepper samples (raw and heat-treated) contained 68 individual pigments, but only 38 of them were micellarized after in vitro digestion. The micellarization of pigments was majorly determined by the interaction effect of processing style (food matrix effect) and fat type (saturated and unsaturated). The highest micellarization was observed with raw peppers. Unsaturated fat increased the micellarization of carotenoid esters, while the impact of fat on the micellarization of free carotenoids seemed to be dependent on pigment structure. The micellarization efficiency was diminished as the esterification level of carotenoids increased. The type of fatty acid moiety and the polarity of the carotenoids modulated their micellarization. Chlorophylls were transformed into pheophytins by heat-processing and digestion, with the pheophytins being stable under gastrointestinal conditions. Micellarization of pheophytins was improved by fat.

Divalent minerals decrease micellarization and uptake of carotenoids and digestion products into Caco-2 cells

Carotenoids are lipophilic, dietary antioxidants with the potential to prevent chronic and age-related diseases. Prior to their availability for physiological functions, carotenoids require micellarization and intestinal uptake, both constituting marginally understood processes. Based on an in vitro digestion model coupled to Caco-2 cells, we assessed the effect of dietary abundant divalent ions on spinach-derived carotenoid micellarization and cellular uptake: Ca and Mg ranging from 7.5 to 25 mmol/L in the digesta and Zn and Fe ranging from 3.8 to 12.5 mmol/L. Both micellarization and uptake were significantly inhibited by minerals in a concentration-dependent manner, with stronger effects for Fe and Zn compared to Ca and Mg. Compared to controls (no mineral addition), fractional micellarization and uptake were decreased to the greatest extent (to 22.5 and 5.0%, respectively; P < 0.001) by 12.5 mmol/L Fe. Effects of Mg were of the least magnitude; at 25 mmol/L, only uptake was decreased significantly to 69.2% of the control value (P < 0.001). Total cellular carotenoid uptake from test meals decreased similarly compared to micellarization; however, decreased β-carotene micellarization was counterbalanced by improved fractional cellular uptakes from the micelles for all ions. Compared to controls, fractional β-carotene uptake from the micelles was greater in samples digested in the presence of Fe, Ca, and Zn, by up to 5-10 times at the highest concentrations of each ion (P < 0.001). Like for the above carotenoids, a high cellular uptake of the epoxycarotenoid conversion products neochrome (from neoxanthin) and luteoxanthin+auroxanthin (from violaxanthin) was also observed. The present results indicate that divalent ions may inhibit carotenoid micellarization and uptake.

Absorption and metabolism of xanthophylls

Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field.

Absorption and metabolism of dietary carotenoids

A number of carotenoids with diverse structures are present in foods and have beneficial effects on human health due to their common antioxidant activity and their respective biological activities. The major carotenoids found in human tissues, however, are limited to several including such as β-carotene, lycopene, and lutein. We have little knowledge of whether carotenoids are selectively absorbed in intestine and metabolized discriminately in the body. Moreover, the metabolic transformation of carotenoids in mammals other than vitamin A formation has not been fully elucidated. Here, the intestinal absorption and oxidative metabolism of dietary carotenoids are reviewed with a focus on dietary xanthophylls.

Simultaneous HPLC-DAD-MS (ESI+) determination of structural and geometrical isomers of carotenoids in mature grapes

Carotenoids are uniquely functional polyene pigments ubiquitous in nature; aside from being responsible for the color of a wide variety of vegetables, interest is being focused on food carotenoids due to their likely health benefits. From analytical point of view, it is important to unequivocally identify individual carotenoid compounds in many food stuffs. Therefore, isolation of standards from natural sources must be encouraged for accurate identifications. Like many fruits, mature grape berries contain numerous carotenoid compounds, mostly found in the skin at levels two to three times higher than in the pulp. Carotenoid compounds in a typical wine grape variety (Negroamaro) grown in Apulian region were investigated by reversed-phase C(30) (RP-30) HPLC-DAD-MS (ESI(+)) analysis. As a consequence of an unusual ionization process of carotenoids, their mass spectra registered in the positive ion mode comprised both protonated molecules and molecular ion radicals with little fragmentation. Additionally, selective collision-induced dissociation (CID) experiments, together with fine structures of the UV-vis spectra, were used to differentiate structural and geometrical isomers. This technique allowed the simultaneous determination of regio- and cis-isomers of lutein (zeaxanthin, 9Z and 9'Z-lutein) and a cis-isomer of β-carotene (9Z- β-carotene), 5,6-epoxy xanthophylls (violaxanthin, (9'Z)-neoxanthin, lutein-5,6-epoxide) and 5,8-epoxy xanthophylls diasteroisomers (neochrome, auroxanthin, luteoxanthin, flavoxanthin, chrysanthemaxanthin).

Antiproliferative effects of carotenoids extracted from Chlorella ellipsoidea and Chlorella vulgaris on human colon cancer cells

The antiproliferative activity of carotenoids separated from marine Chlorella ellipsoidea and freshwater Chlorella vulgaris has been evaluated. HPLC analysis revealed that the main carotenoid from C. ellipsoidea was composed of violaxanthin with two minor xanthophylls, antheraxanthin and zeaxanthin, whereas the carotenoid from C. vulgaris was almost completely composed of lutein. In an MTT assay, both semipurified extracts of C. ellipsoidea and C. vulgaris inhibited HCT116 cell growth in a dose-dependent manner, yielding IC(50) values of 40.73 +/- 3.71 and 40.31 +/- 4.43 microg/mL, respectively. In addition, treatment with both chlorella extracts enhanced the fluorescence intensity of the early apoptotic cell population in HCT116 cells. C. ellipsoidea extract produced an apoptosis-inducing effect almost 2.5 times stronger than that of the C. vulgaris extract. These results indicate that bioactive xanthophylls of C. ellipsoidea might be useful functional ingredients in the prevention of human cancers.

Possible degradation/biotransformation of lutein in vitro and in vivo: isolation and structural elucidation of lutein metabolites by HPLC and LC-MS (atmospheric pressure chemical ionization)

Metabolites of lutein are highly concentrated in the human macula and are known to provide protection against age-related macular degeneration. The aim of this investigation was to characterize the in vitro oxidation products of lutein obtained through photo-oxidation and to compare them with biologically transformed dietary lutein in intestine, plasma, liver, and eyes of rats. In vivo studies involved feeding rats a diet devoid of lutein for 2 weeks to induce deficiency. Rats were divided into two equal groups (n=6/group) and received either micellar lutein by gavage for 10 days or diet supplemented with fenugreek leaves as a lutein source for 4 weeks. Lutein metabolites/oxidation products obtained from in vivo and in vitro studies were characterized by HPLC and LC-MS (APCI) techniques to elucidate their structure. The characteristic fragmented ions resulting from photo-oxidation of lutein were identified as 523 (M(+)+H(+)-3CH(3)), 476 (M(+)+H(+)-6CH(3)), and 551 (M(+)+H(+)-H(2)O). In the eyes, the fragmented molecules resulting from lutein were 13-Z lutein, 13'-Z lutein, 13-Z zeaxanthin, all-E zeaxanthin, 9-Z lutein, 9'-Z lutein, and 3'-oxolutein. Epoxycarotenoids were identified in liver and plasma, whereas anhydrolutein was identified in intestine. This study emphasizes the essentiality of dietary lutein to maintain its status in the retina.

Low bioavailability of dietary epoxyxanthophylls in humans

Epoxyxanthophylls (epoxide-containing xanthophylls), a group of carotenoids, are ubiquitously distributed in edible plants. Among them, neoxanthin in green leafy vegetables and fucoxanthin in brown algae have been reported to exhibit an antiproliferative effect on several human cancer cells in vitro. However, there is little information about the intestinal absorption and metabolic fate of dietary epoxyxanthophylls in humans. To estimate the intestinal absorption of neoxanthin and fucoxanthin in humans, we evaluated the plasma epoxyxanthophyll concentrations before and after 1-week dietary interventions with spinach (Spinacia oleracea) and wakame (Undaria pinnatifida). The epoxyxanthophylls and their metabolites in the plasma extracts were determined by HPLC after partial purification and concentration with solid-phase extraction cartridges. Even after 1 week of spinach intake (3.0 mg neoxanthin/d), the plasma concentrations of neoxanthin and its metabolites (neochrome stereoisomers) remained very low (about 1 nmol/l), whereas those of beta-carotene and lutein were markedly increased. Similarly, the plasma concentration of fucoxanthinol, a gastrointestinal metabolite of fucoxanthin, was < 1 nmol/l after 1 week of wakame intake (6.1 mg fucoxanthin/d). These results indicated that the plasma response to dietary epoxyxanthophylls was very low in humans even after 1-week intake of epoxyxanthophyll-rich diets.

Carotenoids in white- and red-fleshed loquat fruits

Fruits of 23 loquat ( Eriobotrya japonica Lindl.) cultivars, of which 11 were white-fleshed and 12 red-fleshed, were analyzed for color, carotenoid content, and vitamin A values. Color differences between two loquat groups were observed in the peel as well as in the flesh. beta-Carotene and lutein were the major carotenoids in the peel, which accounted for about 60% of the total colored carotenoids in both red- and white-fleshed cultivars. beta-Cryptoxanthin and, in some red-fleshed cultivars, beta-carotene were the most abundant carotenoids in the flesh, and in total, they accounted for over half of the colored carotenoids. Neoxanthin, violaxanthin, luteoxanthin, 9- cis-violaxanthin, phytoene, phytofluene, and zeta-carotene were also identified, while zeaxanthin, alpha-carotene, and lycopene were undetectable. Xanthophylls were highly esterified. On average, 1.3- and 10.8-fold higher levels of colored carotenoids were observed in the peel and flesh tissue of red-fleshed cultivars, respectively. The percentage of beta-carotene among colored carotenoids was higher in both the peel and the flesh of red-fleshed cultivars. Correlations between the levels of total colored carotenoids and the color indices were analyzed. The a* and the ratio of a*/ b* were positively correlated with the total content of colored carotenoids, while L*, b*, and H degrees correlated negatively. Vitamin A values, as retinol equivalents (RE), of loquat flesh were 0.49 and 8.77 microg/g DW (8.46 and 136.41 microg/100 g FW) on average for white- and red-fleshed cultivars, respectively. The RE values for the red-fleshed fruits were higher than fruits such as mango, red watermelon, papaya, and orange as reported in the literature, suggesting that loquat is an excellent source of provitamin A.

A highly polar xanthophyll of 9'-cis-neoxanthin induces apoptosis in HCT116 human colon cancer cells through mitochondrial dysfunction

Highly polar xanthophylls of 9'-cis-neoxanthin (neoxanthin) and fucoxanthin, which have the characteristic structure of an epoxy group and an allenic bond, were previously found to induce apoptosis in human prostate cancer cells. In the present study, we found apoptosis induction by neoxanthin in HCT116 human colon cancer cells and examined the induction mechanism. The cells exposed to 20 microM neoxanthin clearly showed chromatin condensation, DNA fragmentation, and an increase in hypodiploid cells. Neoxanthin treatment increased the activities of caspase-3, -8 and -9, and the protein levels of their active subunits, except in the case of caspase-8. The treatment also caused the loss of mitochondrial transmembrane potential at an early stage and subsequently the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to cytosol. The exposure of neoxanthin directly to mitochondria isolated from the cells enhanced the release of cytochrome c and AIF in a dose-dependent manner. Approximately 50% of the neoxanthin taken up into the HCT116 cells accumulated in the mitochondrial fraction. These results suggest that the accumulation of neoxanthin in mitochondria causes the loss of mitochondrial transmembrane potential and thereafter releases cytochrome c and AIF, leading to the execution of apoptosis.

Carotenoid profile modification during refrigerated storage in untreated and pasteurized orange juice and orange juice treated with high-intensity pulsed electric fields

A comparative study was made of the evolution and modification of various carotenoids and vitamin A in untreated orange juice, pasteurized orange juice (90 degrees C, 20 s), and orange juice processed with high-intensity pulsed electric fields (HIPEF) (30 kV/cm, 100 micros), during 7 weeks of storage at 2 and 10 degrees C. The concentration of total carotenoids in the untreated juice decreased by 12.6% when the juice was pasteurized, whereas the decrease was only 6.7% when the juice was treated with HIPEF. Vitamin A was greatest in the untreated orange juice, followed by orange juice treated with HIPEF (decrease of 7.52%) and, last, pasteurized orange juice (decrease of 15.62%). The decrease in the concentrations of total carotenoids and vitamin A during storage in refrigeration was greater in the untreated orange juice and the pasteurized juice than in the juice treated with HIPEF. During storage at 10 degrees C, auroxanthin formed in the untreated juice and in the juice treated with HIPEF. This carotenoid is a degradation product of violaxanthin. The concentration of antheraxanthin decreased during storage, and it was converted into mutatoxanthin, except in the untreated and pasteurized orange juices stored at 2 degrees C.

Differences in the carotenoid content of ordinary citrus and lycopene-accumulating mutants

High-performance liquid chromatography, coupled with photodiode array detection, was used to analyze the carotenoid composition of peel and juice vesicle tissues of ordinary and lycopene-accumulating mutants (referred to as red mutants in this article) of orange, pummelo, and grapefruit. Thirty-six major carotenoids, including some cis-trans isomers, were separated on a C30 reversed phase column, and 23 of them were identified on the basis of retention times and spectral characteristics with authentic standards. Carotenoid profiles varied with tissue types, citrus species, and mutations. beta-Citraurin occurred in the peel of oranges but not in juice vesicles, whereas the reverse was found for violaxanthin, 9-cis-violaxanthin, and luteoxanthin. The diversity of carotenoids in peel and juice vesicle tissues and the fact that there was over 250 times higher content of total carotenoids in peels of Yuhuan pummelo than juice vesicles suggested that the biosynthesis of carotenoids in these two tissues was independent and exchange of carotenoids between the tissues was not likely. Lutein was observed in peels of pummelos and grapefruits and juice vesicles of ordinary pummelo but not in orange tissues. Accumulation of lycopene and beta-carotene was observed in red mutant citrus, except for the peel of Cara Cara red orange. Additionally, phytoene accumulated in all tissues except for the peel of Chuzhou Early Red pummelo. No obvious change in the total content of xanthophylls was observed in the Cara Cara red orange. Ordinary grapefruit (Marsh) tissues and pummelo (Yuhuan) juice vesicles were almost devoid of carotenoids, and in red mutants, the content of total carotenoids increased dramatically up to 790-fold. The different changes in carotenoid content and profiles in mutant(s) of different citrus species suggest that the underlying mechanisms for the mutations might be different.

Effect of high-intensity pulsed electric fields processing and conventional heat treatment on orange-carrot juice carotenoids

Liquid chromatography (LC) was the method of choice for quantification of carotenoids (including geometrical isomers) to evaluate the effects of high-intensity pulsed electric field (HIPEF), a nonthermal preservation method, with different parameters (electric field intensities and treatment times), on an orange-carrot juice mixture (80:20, v/v). In parallel, a conventional heat treatment (98 degrees C, 21 s) was applied to the juice. HIPEF processing generally caused a significant increase in the concentrations of the carotenoids identified as treatment time increased. HIPEF treatment at 25 and 30 kV/cm provided a vitamin A concentration higher than that found in the pasteurized juice.