Evaluation of Food Intake Biomarkers for Red Bell Peppers in Human Urine Based on HPLC-MS/MS Analysis

SCOPE

The validation of dietary biomarkers is essential for the use in objective and quantitative assessment of the human dietary intake. In this study, the urinary excretion of previously identified potential biomarkers after intake of red bell peppers is analyzed.

METHODS AND RESULTS

The urine samples obtained after a two-phase dietary intervention study in which 14 volunteers participated are quantitatively analyzed by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) after an extensive validation. In the first phase, the volunteers abstain completely from bell peppers and paprika products (control group) and in the second phase, the volunteers consume a defined amount of fresh red bell peppers (case group). After analysis, all potential biomarkers show high dispersions of their concentration, indicating interindividual differences. The glucuronidated apocarotenoid (compound 1), which probably resulted from the main carotenoids of red Capsicum fruits, shows a rapid urinary excretion. The other glucuronidated metabolites (compounds 2-8), described as potential derivatives of capsianosides from Capsicum, show a slightly delayed but longer urinary excretion.

CONCLUSIONS

A correlation between an intake of red bell pepper and the urinary excretion of recently described potential biomarkers is observed. Due to large interindividual differences, it is reasonable to assume that at least the qualitative detection of the consumption of bell peppers and possibly all Capsicum fruits is feasible.

Fast and High-Efficiency Synthesis of Capsanthin in Pepper by Transient Expression of Geminivirus

The color of the chili fruit is an important factor that determines the quality of the chili, as red chilies are more popular among consumers. The accumulation of capsanthin is the main cause of reddening of the chili fruit. Capsanthin is an important metabolite in carotenoid metabolism, and its production level is closely linked to the expression of the genes for capsanthin/capsorubin synthase (CCS) and carotenoid hydroxylase (CrtZ). We reported for the first time that the synthesis of capsanthin in chili was enhanced by using a geminivirus (Bean Yellow Dwarf Virus). By expressing heterologous β-carotenoid hydroxylase (CrtZ) and β-carotenoid ketolase (CrtW) using codon optimization, the transcription level of the CCS gene and endogenous CrtZ was directly increased. This leads to the accumulation of a huge amount of capsanthin in a very short period of time. Our results provide a platform for the rapid enhancement of endogenous CCS activity and capsanthin production using geminivirus in plants.

Biological Importance, Pharmacological Activities, and Nutraceutical Potential of Capsanthin: A Review of Capsicum Plant Capsaicinoids

BACKGROUND

Carotenoids are natural hydrocarbons that play an important role in photomorphogenesis, photosynthesis, photoprotection, development, and defense mechanism of plants. Carotenoids have good anti-oxidants and provitamin A contents with their additional colorant nature, which are indispensable to plants and human diets. Capsicum species are well known for their culinary uses worldwide; they are not only cultivated as vegetables but used in numerous medicinal preparations as well due to their medicinal aspects. This article aims to collect data on the beneficial aspects of capsaicinoids with a major emphasis on capsanthin.

METHODS

In order to instigate the biological potential and therapeutic benefit of capsanthin in medicine, in the present work, scientific research data on capsanthin were collected from different literature sources and analyzed. The biological potential of Capsicum annuum in medicine was also investigated through literature data analysis of different scientific research work. Scientific data on capsanthin were collected from Google, Google Scholar, PubMed, Science Direct, and Scopus using the term capsanthin and capsicum in the present work. Detailed pharmacological activities of capsanthin were presented and discussed in the present work through scientific data analysis of research work. Analytical techniques for the separation, isolation, and identification of capsanthin were taken into consideration in this work.

RESULTS

Scientific data analysis revealed the biological importance and therapeutic benefit of capsanthin and capsicum in medicine. Capsicum annuum is a member of the Solanaceae family, which is one of the most cultivated spices worldwide. Capsaicinoids are one of the main classes of phytochemicals found in chili peppers, i.e., Capsicum annuum, and are mainly responsible for the pungent and spicy flavor of chili peppers. Capsanthin is a crystalline red color pigment found as the main component of Capsicum annuum fruits during ripening. Capsanthin is also found in Lilium, Aesculus, Berberis, and Asparagus officinalis. Chemically, capsanthin contains a cyclopentane ring, 11 conjugated double bonds, and a conjugated keto group. Capsanthin is a powerful antioxidant, exhibits anti-tumor activities, attenuates obesity-induced inflammation, and raises plasma HDL cholesterol levels. Scientific studies have proven the pharmacological benefits of capsanthin in medicine as it is helpful in pain relief, cardioprotection, weight loss, and body temperature regulation. Moreover, it also has anti-inflammatory, anticancer, antioxidant, and antimicrobial activities. In the literature database, numerous extraction and isolation techniques have been documented for capsanthin. In addition, the analytical techniques and other bioanalytical tools for the isolation and identification of capsanthin were also discussed in the present article.

CONCLUSION

Medicinal importance and pharmacological activities of capsanthin were reviewed and discussed in this paper. This review aimed to highlight the literature on capsanthin in drug discoveries with their analytical development.

Speculation of Sphingolipids in Capsanthin by Ultra-Performance Liquid Chromatography Coupled with Electrospray Ionization-Quadrupole-Time-of-Flight Mass Spectrometry

Sphingolipids are constituents of cellular membranes and play important roles in cells. As nutraceutical compounds in foods, sphingolipids have been proven to be critical for human health. Therefore, the sphingolipids content of capsanthin was established based on ultra-performance liquid chromatography coupled with electrospray ionization-quadrupole-time-of-flight mass spectrometry. A total number of 40 sphingolipids were successfully identified, including 20 Glucosylceramides and 20 Ceramides. The predominant GlcCers contain 4-hydroxy-8-sphingenine t18:1 (8) with different structures of α-OH fatty acids. For the Cers, the main long-chain bases are 4-hydroxy-8-sphingenine t18:1 (8) and 4-hydroxysphingenine (t18:0) with different structures of α-OH or α, β-di (OH) fatty acids.

The Identification and Quantitative Analysis of Unusual Keto-Carotenoids in Ripe Fruits of Maclura tricuspidate and Its Potential as a Valuable Source of Cryptocapsin

Ripe fruits of Maclura tricuspidata (MT) are used as food material and a natural colorant in Korea. Although MT fruits have a deep red color due to carotenoid-like pigments, their chemical nature has not been explored in detail so far. The present study aimed at elucidating the chemical structures and composition of carotenoids in MT fruits and changes at different maturity stages. Two carotenoids from saponified MT fruit extract were isolated using repeated silica gel column chromatography. Based on interpretations of spectroscopic data, these compounds were determined as keto-carotenoids, i.e., capsanthin (3,3'-dihydroxy-β,κ-caroten-6'-one) and cryptocapsin (3'-hydroxy-β,κ-caroten-6'-one), and the contents of individual carotenoids were quantified with HPLC based on calibration curves obtained from authentic standards. The contents of capsanthin and cryptocapsin in the sample of saponified MT fruits were 57.65 ± 1.97 µg/g and 171.66 ± 4.85 μg/g as dry weight base (dw). The majority of these keto-carotenoids in the MT fruits were present in esterified forms with lauric, myristic or palmitic acid rather than in their free forms. The results also showed that esterification of these compounds occurred starting from early stage (yellow-brownish stage) of maturation. Considering the high cryptocapsin content, MT fruits can be applied as a potentially valuable source of cryptocapsin for food and medicinal application as well as a source of provitamin A.

Esterification of Lutein from Japanese Knotweed Waste Gives a Range of Lutein Diester Products with Unique Chemical Stability

A valorization strategy for an aggravating type of plant waste is put to the test herein. It envisions the use of Japanese knotweed green leaves as a sustainable source of free lutein, from which bioactive diesters could be prepared as potential value-added products with improved properties. To this end, 13 structurally distinct model lutein diesters were synthesized and the relationships between their structure and stability were systematically determined. The forced degradation data show that the stability of a particular lutein diester may depend to a large extent on the type of exposure (elevated temperature, light, oxidant, or acidic environment) and, more importantly, not every esterification attempt necessarily leads to an enhancement of lutein's chemical stability. However, three branched and bulky products-lutein di(2,2-dimethylpropanoate), lutein di(2-methylpropanoate), and lutein di(3-methylbutanoate)-proved to be particularly relevant, as they consistently exhibited 1.5-21-fold higher stability compared to free lutein, regardless of the stress conditions used. Finally, we show that the Japanese knotweed plant matrix had a significant negative or positive effect on pigment degradation kinetics that could not be easily predicted. Thus, the proposed valorization strategy is quite feasible, but the esterification approach should be tailored to the intended use of a lutein diester.

Identification of Potential Urinary Biomarkers for Bell Pepper Intake by HPLC-HRMS-Based Metabolomics and Structure Elucidation by NMR

Dietary biomarkers show great promise for objectively assessing the food intake in humans. In this study, potential urinary biomarkers for red bell pepper intake were identified based on a dietary intervention study and a comprehensive metabolomics approach. Spot urine samples from 14 volunteers were collected in the two phases of the study (control phase: abstaining from any bell pepper/paprika products; case phase: consumption of a defined amount of fresh red bell pepper and abstaining from any further bell pepper/paprika products) and analyzed by high-performance liquid chromatography high-resolution mass spectrometry (HPLC-HRMS). Comparison of the obtained metabolomics data using statistical analysis revealed that the respective urine metabolomes differ significantly, which was attributable to the bell pepper intake. Some of the most discriminating metabolites were selected and isolated from human urine for unequivocal structure elucidation by nuclear magnetic resonance (NMR) spectroscopy. Herein, seven novel glucuronidated metabolites most likely derived from capsanthin and capsianosides were identified, implying their potential application as dietary biomarkers for the entire Capsicum genus.

Capsanthin, a Plant-Derived Xanthophyll: a Review of Pharmacology and Delivery Strategies

Capsanthin, a brightly orange-red-coloured pigment responsible for the peculiar red colour of paprika fruits (Capsicum annuum), belongs to xanthophylls, a class of oxygen-containing carotenoids. The characteristic chemical structure of capsanthin containing a keto group in conjunction with a long chain of 11 conjugated dienes is responsible for its strong radical scavenging and singlet oxygen quenching ability. Chemopreventive, antitumour, skin photo-protective, anti-inflammatory, and antidiabetic activities demonstrated by capsanthin are a consequence of its potent antioxidant action. Anti-obesity, anti-adipogenic, and antihyperlipidaemic activities are some of the more important features of capsanthin. With natural origin, bright red colour, and array of health benefits, capsanthin has a potential to be translated into a commercial cosmeceutical, nutraceutical, and/or pharmaceutical. However, the very low aqueous solubility of capsanthin is responsible for its highly variable and poor oral bioavailability. Moreover, its susceptibility to degradation due to heat, light, oxygen, and moisture poses challenges in the development of stable formulations for this otherwise meritorious compound. The current review presents various pharmacological activities of capsanthin and their underlying mechanisms. The review further discusses hitherto explored formulation strategies to improve solubility and stability of capsanthin. Graphical abstract.

Protective Role of Dietary Capsanthin in a Mouse Model of Nonalcoholic Fatty Liver Disease

Capsanthin is the main carotenoid compound in red paprika (Capsicum annuum L.). However, little is known about the beneficial effects of capsanthin in nonalcoholic fatty liver disease (NAFLD). In this study, the hepatoprotective activity of capsanthin was investigated in a mouse model of NAFLD. Apolipoprotein-E knockout mice were fed with normal diet, Western-type diet (WD, NAFLD model), WD with capsanthin (0.5 mg/kg of body weight/day, CAP), WD with capsanthin-rich extract (25 mg/kg of body weight/day; CRE), or WD with red paprika powder (25 mg/kg of body weight/day, RPP) for 12 weeks. The carotenoid content in CRE or RPP was analyzed using ultraperformance liquid chromatography. The capsanthin concentration in CRE was 2067 mg/100 g of dry weight, which was 63% of total carotenoids. The oral administration of CRE or capsanthin significantly reduced the WD-induced increase in body weight and lipid accumulation in the liver (vs. the RPP group). In addition, CRE or capsanthin significantly inhibited the WD-induced increase in cholesterol and low-density lipoprotein levels. Furthermore, CRE or capsanthin showed reduced levels of plasma alanine and aspartate aminotransferase (ALT and AST, respectively), suggesting a steatohepatitis protective effect. Capsanthin regulated mRNA levels of peroxisome proliferator-activated receptor alpha (Pparα), carnitine palmitoyltransferase 1A (Cpt1a), acyl-CoA oxidase 1 (Acox1), and sterol regulatory element binding protein-1c (Srebp1c), which are associated with hepatic fatty acid metabolism. Overall, our results suggest that the capsanthin of red paprika plays a protective role against hepatic steatosis/steatohepatitis in NAFLD.

Extraction of capsanthin from Capsicum annum L fruits and its effect on carbomer-induced intraocular pressure in Albino Wistar rats

The present study was aimed to explore the antiglaucoma activity of capsanthin enriched fraction (CEF) of Capsicum annum L fruits against carbomer-induced experimental glaucoma in Albino Wistar rats. CEF was orally administered to carbomer-induced glaucomatous rats, and pilocarpine 2% eye drops were used as a standard drug. Intraocular pressure (IOP) levels were determined after oral administration of a low, medium, and a high dose of CEF (20, 40, and 80 mg/kg bwt) in glaucomatous rats. In rats with elevated IOP in both eyes, oral administration of CEF resulted in a significant reduction in IOP (p < .05) even at a low dose of 20 mg/Kg body weight. There were no treatment-related changes in histopathology, hematology, and clinical chemistry parameters. Thus, CEF when administered orally in IOP-bearing rats successfully reduced IOP without any adverse effects. PRACTICAL APPLICATIONS: Capsanthin enriched fraction can be used to prevent permanent vision loss due to age-related macular diseases and high intraocular pressure. The intraocular pressure reduction action of capsanthin can be useful in the treatment of glaucoma. The medication available to treat glaucoma are topical drugs, and for the first time, we proved the oral supplementation of capsanthin from a food source can reduce the intraocular pressure in rats.

Capsanthin Production in Escherichia coli by Overexpression of Capsanthin/Capsorubin Synthase from Capsicum annuum

Capsanthin, a characteristic red carotenoid found in the fruits of red pepper (Capsicum annuum), is widely consumed as a food and a functional coloring additive. An enzyme catalyzing capsanthin synthesis was identified as capsanthin/capsorubin synthase (CCS) in the 1990s, but no microbial production of capsanthin has been reported. We report here the first successful attempt to biosynthesize capsanthin in Escherichia coli by carotenoid-pathway engineering. Our initial attempt to coexpress eight enzyme genes required for capsanthin biosynthesis did not detect the desired product. The dual activity of CCS as a lycopene β-cyclase as well as a capsanthin/capsorubin synthase likely complicated the task. We demonstrated that a particularly high expression level of the CCS gene and the minimization of byproducts by regulating the seven upstream carotenogenic genes were crucial for capsanthin formation in E. coli. Our results provide a platform for further study of CCS activity and capsanthin production in microorganisms.

Capsanthin induces G1/S phase arrest, erlotinib-sensitivity and inhibits tumor progression by suppressing EZH2-mediated epigenetically silencing of p21 in triple-negative breast cancer cells

Capsanthin is a naturally occurring red pepper carotenoid with possible antitumor activity, but its antitumor mechanisms have yet to be delineated. We tested the anti-proliferative activity of capsanthin with human triple-negative breast cancer (TNBC) and found that cell proliferation was inhibited after 24, 48 and 72 h of treatment. We also investigated the cellular and molecular mechanisms of the antitumor efficacy of capsanthin on TNBC cells and found that capsanthin delayed cell-cycle progression at the G1/S stage, that cyclin A expression was suppressed, and that p21 expression was upregulated. Capsanthin also inhibited the EZH2 expression and EZH2 could binding to the p21 promoter in TNBC cells. We further discovered that capsanthin has synthetic effects when combined with erlotinib (Tarceva). In the animal experiment, we found that the capsanthin-induced inhibition of TNBC cell proliferation decreased the incidence of the initiation and growth of TNBC cell–derived tumors in mice. Our study reveals that capsanthin exerted antitumor effects through delaying cell-cycle progression, induces erlotinib-sensitivity and inhibits tumor progression by inhibiting EZH2/p21 axis, and capsanthin is a potential drug candidate for development of a safe and effective therapy against TNBCs, especially for TNBCs that have developed resistance to targeting therapy.

Effects of paprika carotenoid supplementation on bone turnover in postmenopausal women: a randomized, double-blind, placebo-controlled, parallel-group comparison study

Background

Paprika (Capsicum annuum L.) is a good source of carotenoids, including capsanthin, β-carotene, β-cryptoxanthin, and zeaxanthin. Several epidemiological studies have shown a beneficial association of intake of these carotenoids or their blood concentration with bone mineral density (BMD) and fracture risk. However, little information is available regarding the effect of intake of these carotenoids on bone metabolism in postmenopausal women.

Objective

The objective of the present study was to investigate the effects of paprika carotenoid extract (PCE) on bone turnover in healthy, postmenopausal women.

Design

We conducted a randomized, double-blind, placebo-controlled, parallel-group comparison study. One hundred participants were randomly assigned to PCE or placebo groups. Each group was given a 20 mg PCE (equivalent to 1.4 mg of carotenoids) a day or a placebo for 24 weeks. We measured bone resorption markers (tartrate-resistant acid phosphatase 5b [TRACP-5b] and serum type I collagen cross-linked N-telopeptide [sNTX]) at 12 and 24 weeks and bone formation markers (bone alkaline phosphatase and osteocalcin) at 24 weeks.

Results

The percentage decrease of TRACP-5b at 24 weeks was significantly higher for PCE than the placebo. There were no significant differences in sNTX or bone formation markers, although PCE decreased each marker compared with the placebo.

Conclusion

Our findings suggest that PCE supplementation suppresses bone resorption and contributes to maintaining bone quality in postmenopausal women.

Safety and efficacy of saponified paprika extract, containing capsanthin as main carotenoid source, for poultry for fattening and laying (except turkeys)

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of saponified paprika extract, containing capsanthin as main carotenoid source, for poultry for fattening and laying (except turkeys). The saponified paprika (Capsicum annuum) extract contains various carotenoids at a concentration of 25-90 g/kg of which capsanthin being the major one with quantity specified as > 35% of total carotenoids (TC). The maximum recommended use level of 40 mg TC/kg feed is safe for chickens for fattening and laying hens. The margin of safety is at least 6. This conclusion is extrapolated to minor poultry species for fattening and laying. The saponified paprika extract is not genotoxic. Based on the no observed effect level (NOEL) of the 90-day study in rat and the exposure estimates, the Panel considered that there would be an adequate margin of exposure (between 700 and 2000) to conclude that the level of exposure to residues of the saponified paprika (C. annuum) extract (capsanthin not less than 35% of TCs) in animal tissues and products does not raise concern for the safety for the consumer. The saponified paprika extract is a viscous paste and as such users will not be exposed by inhalation. The applicant recognises that the extract may be irritant to skin and eyes. The FEEDAP Panel cannot conclude on the potential of any preparation to be toxic by inhalation, skin/eye irritant or skin sensitiser since no data were submitted. The use of saponified paprika extract in poultry feed raised no concern for the environment. Saponified paprika extract has the potential to pigment broiler skin and egg yolk. This conclusion is extrapolated to minor poultry species for fattening and laying.

Detection of quantitative trait loci for capsanthin content in pepper (Capsicum annuum L.) at different fruit ripening stages

Capsanthin, the main carotenoid of red pepper fruits, is beneficial for human health. To breed pepper (Capsicum annuum L.) with high capsanthin content by marker-assisted selection, we constructed a linkage map of doubled-haploid (DH) lines derived from a cross of two pure lines of C. annuum ('S3586' × 'Kyoto-Manganji No. 2'). The map, designated as the SM-DH map, consisted of 15 linkage groups and the total map distance was 1403.8 cM. Mapping of quantitative trait loci (QTLs) for capsanthin content detected one QTL on linkage group (LG) 13 at 90 days after flowering (DAF) and one on LG 15 at 45 DAF; they were designated Cst13.1 and Cst15.1, respectively. Cst13.1 explained 17.0% of phenotypic variance and Cst15.1 explained 16.1%. We grouped DH lines according to the genotypes of markers adjacent to Cst13.1 and Cst15.1 on both sides. The DH lines with the alleles of both QTLs derived from 'S3586' showed higher capsanthin content at 45 and 90 DAF than the other lines. This is the first identification of QTLs for capsanthin content in any plant species. The data obtained here will be useful in marker-assisted selection for pepper breeding for high capsanthin content.

Dose rates of electron beam and gamma ray irradiation affect microbial decontamination and quality changes in dried red pepper (Capsicum annuum L.) powder

BACKGROUND

Due to differences in radiation sources (electron beam from electron accelerator, gamma ray from ⁶⁰ Co radionuclide) and energy delivery time (dose rate, kGy/time), the effects on foods are expected to be different with regard to chemical quality change and microbial decontamination. To better understand this impact, effects of variable dose rates of electron beam (EB, kGy s^-1 ) and gamma rays (GR, kGy h^-1 ) on microbial reduction, capsanthin content, and color parameters of red pepper (Capsicum annuum L.) powders (RPP) were determined. RPP samples were irradiated with 3 kGy absorbed dose, at variable dose rates of 1 and 5 kGy s^-1 of EB (10 MeV/10 kW), and 1.8 and 9 kGy h^-1 of GR (⁶⁰ Co).

RESULTS

Aerobic plate counts (APC) as well as yeast and mold counts of non-irradiated samples were 7.12 log CFU g^-1 and 6.62 log CFU g^-1 , respectively. EB and GR reduced these by 2-3 log CFU g^-1 . A lower dose rate (1 kGy s^-1 ) of EB was more effective for microbial reduction than a higher dose rate (5 kGy s^-1 ). In contrast, a higher dose rate (9 kGy h^-1 ) of GR efficiently decreased APC compared to a lower dose rate (1.8 kGy h^-1 ). Higher EB and GR dose rates significantly decreased the capsanthin content and Hunter's red color (a* value).

CONCLUSION

Low EB (kGy s^-1 ) and high GR (kGy h^-1 ) dose rates are recommended for microbiological safety of RPP with negligible changes in color attributes visible to the human eye, in contrast to the measured values. Thus the study demonstrates that the influence of absorbed dose is dependent on the applied dose rates. © 2018 Society of Chemical Industry.

Safety Evaluation and Plasma Carotenoid Accumulation in Healthy Adult Subjects after 12 Weeks of Paprika Oleoresin Supplementation

Paprika oleoresin is obtained by solvent extraction from Capsicum annuum L. fruits and contains multiple carotenoids, such as capsanthin, β-carotene, zeaxanthin, and β-cryptoxanthin, which are considered protective against various diseases. Herein, we investigated the effect of paprika oleoresin supplementation on plasma carotenoid accumulation and evaluated the safety of the oleoresin. We used a double-blinded, placebo-controlled comparative clinical study design and tested the effects of varying doses in healthy adult subjects. In total, 33 subjects were randomly divided into three groups to take capsules containing 0, 20, or 100 mg of paprika oleoresin daily for 12 consecutive weeks. Plasma carotenoid concentrations were measured at 0, 4, 8, and 12 weeks, and the safety of paprika oleoresin capsules was investigated using analyses of blood biochemistry, hematology, and urine contents. In these experiments, β-cryptoxanthin and zeaxanthin dose-dependently accumulated in plasma within the dose range of the study over 12 consecutive weeks of paprika oleoresin supplementation. Moreover, β-cryptoxanthin accumulated to higher levels than the other paprika oleoresin carotenoids. In contrast, capsanthin was not detected in plasma before or during the 12-week treatment period. Finally, no adverse events were associated with intake of paprika oleoresin (20 and 100 mg/day) in safety evaluations. Paprika oleoresin is a suitable source of carotenoids, especially β-cryptoxanthin.

Reaction of Paprika Carotenoids, Capsanthin and Capsorubin, with Reactive Oxygen Species

The reaction of paprika carotenoids, capsanthin and capsorubin, with reactive oxygen species (ROS), such as superoxide anion radical (·O2(-)), hydroxyl radical (·OH), and singlet oxygen ((1)O2), was analyzed by LC/PDA ESI-MS and ESR spectrometry. Capsanthin formed both the 5,6-epoxide and 5,8-epoxide by reaction with ·O2(-) and ·OH. Furthermore, capsanthin also formed 5,6- and 5,8-endoperoxide on reaction with (1)O2. The same results were obtained in the case of capsanthin diacetate. On the other hand, capsorubin showed higher stability against these ROS. Capsorubin formed 7,8-epoxide on reaction with ·O2(-) and ·OH and 7,8-endoperoxide on reaction with (1)O2.

Deposition Form and Bioaccessibility of Keto-carotenoids from Mamey Sapote (Pouteria sapota), Red Bell Pepper (Capsicum annuum), and Sockeye Salmon (Oncorhynchus nerka) Filet

The ultrastructure and carotenoid-bearing structures of mamey sapote (Pouteria sapota) chromoplasts were elucidated using light and transmission electron microscopy and compared to carotenoid deposition forms in red bell pepper (Capsicum annuum) and sockeye salmon (Oncorhynchus nerka). Globular-tubular chromoplasts of sapote contained numerous lipid globules and tubules embodying unique provitamin A keto-carotenoids in a lipid-dissolved and presumably liquid-crystalline form, respectively. Bioaccessibility of sapotexanthin and cryptocapsin was compared to that of structurally related keto-carotenoids from red bell pepper and salmon. Capsanthin from bell pepper was the most bioaccessible pigment, followed by sapotexanthin and cryptocapsin esters from mamey sapote. In contrast, astaxanthin from salmon was the least bioaccessible keto-carotenoid. Thermal treatment and fat addition consistently enhanced bioaccessibility, except for astaxanthin from naturally lipid-rich salmon, which remained unaffected. Although the provitamin A keto-carotenoids from sapote were highly bioaccessible, their qualitative and quantitative in vivo bioavailability and their conversion to vitamin A remains to be confirmed.

Cloning and characterization of the CarbcL gene related to chlorophyll in pepper (Capsicum annuum L.) under fruit shade stress

Light is an important environmental factor for fruit development and ripening in pepper plant. Fruit bagging is a significant agrotechnology practiced for the illumination regulation of fruits; some previous researches have shown that fruit bagging could improve the appearance and external quality of fruits and cause them to mature early. However, it would decrease the intrinsic qualities of fruits; especially, fruit bagging could decrease the content of capsanthin in peppers. On the basis of these details, fruit bagging was used as the method of fruit shade stress in this study to explore the characteristics and molecular mechanisms of pepper fruit's color change under shade stress. By using cDNA-AFLP under fruit shading, a fragment related to fruit color was obtained. Next, the full-length coding sequence of the gene was cloned from the pepper fruits. Homologous gene alignment confirmed that the gene has high homology with the rbcL gene, named CarbcL. The function of the CarbcL gene was identified through virus-induced gene silencing (VIGS); it was found that the fruit color changed completely from green to red except for some residue of green fleck when CarbcL gene was silenced, and the green color of fruits had not fully faded in the control group and the empty vector group. The combine determination of chlorophyll content showed that CarbcL was involved in the metabolic control of chlorophyll in pepper fruits; subsequently, HPLC was used to determine the content of capsanthin in pepper fruit which the CarbcL gene was silencing, and it was also found that the content of capsanthin decreased appreciably. These results further confirmed that CarbcL gene was involved in the adjustment of chlorophyll and capsanthin.

Effects of silencing key genes in the capsanthin biosynthetic pathway on fruit color of detached pepper fruits

BACKGROUND

There are many varieties of carotenoids in pepper fruits. Capsanthin is a red carotenoid that gives mature pepper fruits their red color. The red color in pepper fruits is regulated mainly by the genes capsanthin/capsorubin synthase(Ccs), phytoene synthase(Psy), lycopene-β-cyclase(Lcyb) and β-carotene hydroxylase(Crtz). There has been very limited research work related to the development and change in the red color during fruit formation and when a certain gene or several genes are deleted. In this paper, we constructed viral vectors, using the tobacco rattle virus (TRV), to carry the target gene to infect detached pepper fruits, and observed the fruits' color change. We used real-time quantitative PCR to analyze the gene silencing efficiency. At the same time, HPLC was used to determine the content of capsanthin and carotenoids that are associated with capsanthin synthesis when key genes in the pepper fruits were silenced.

RESULTS

These genes (Ccs, Psy, Lcyb and Crtz) were individually silenced through virus induced gene silencing (VIGS) technology, and pepper fruits from red fruit cultivars showed an orange or yellow color. When several genes were silenced simultaneously, the fruit also did not show the normal red color. Gene expression analysis by real-time quantitative PCR showed 70-80% efficiency of target gene silencing when using the VIGS method. HPLC analysis showed that the contents of carotenoids associated with capsanthin synthesis (e.g. β-carotene, β-cryptoxanthin or zeaxanthin) were decreased in varying degrees when silencing a gene or several genes together, however, the content of capsanthin reduced significantly. The synthesis of capsanthin was influenced either directly or indirectly when any key gene was silenced. The influence of the target genes on color changes in pepper fruits was confirmed via the targeted silencing of them.

CONCLUSIONS

VIGS was a good method to study the molecular mechanism of pepper fruit color formation. By using virus induced gene silencing technology, capsanthin synthesis genes in pepper fruits were silenced individually or simultaneously, and pepper fruit color changes were observed. This provides a platform to further explore the molecular mechanism of pepper fruit color formation.

Cloning and functional characterization of a gene for capsanthin-capsorubin synthase from tiger lily (Lilium lancifolium Thunb. 'Splendens')

The orange color of tiger lily (Lolium lancifolium 'Splendens') flowers is due, primarily, to the accumulation of two κ-xanthophylls, capsanthin and capsorubin. An enzyme, known as capsanthin-capsorubin synthase (CCS), catalyzes the conversion of antheraxanthin and violaxanthin into capsanthin and capsorubin, respectively. We cloned the gene for capsanthin-capsorubin synthase (Llccs) from flower tepals of L. lancifolium by the rapid amplification of cDNA ends (RACE) with a heterologous non-degenerate primer that was based on the sequence of a gene for lycopene β-cyclase (lcyB). The full-length cDNA of Llccs was 1,785 bp long and contained an open reading frame of 1,425 bp that encoded a polypeptide of 474 amino acids with a predicted N-terminal plastid-targeting sequence. Analysis by reverse transcription-PCR (RT-PCR) revealed that expression of Llccs was spatially and temporally regulated, with expression in flower buds and flowers of L. lancifolium but not in vegetative tissues. Stable overexpression of the Llccs gene in callus tissue of Iris germanica, which accumulates several xanthophylls including violaxanthin, the precursor of capsorubin, resulted in transgenic callus whose color had changed from its normal yellow to red-orange. This novel red-orange coloration was due to the accumulation of two non-native κ-xanthophylls, capsanthin and capsorubin, as confirmed by HPLC and ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis with authentic standards. Cloning of the Llccs gene should advance our understanding of the molecular and genetic mechanisms of the biosynthesis of κ-carotenoids in general and in the genus Lilium in particular, and will facilitate transgenic alterations of the colors of flowers and fruits of many plant species.

Carotenoid accumulation in orange-pigmented Capsicum annuum fruit, regulated at multiple levels

The pericarp of Capsicum fruit is a rich dietary source of carotenoids. Accumulation of these compounds may be controlled, in part, by gene transcription of biosynthetic enzymes. The carotenoid composition in a number of orange-coloured C. annuum cultivars was determined using HPLC and compared with transcript abundances for four carotenogenic enzymes, Psy, LcyB, CrtZ-2, and Ccs determined by qRT-PCR. There were unique carotenoid profiles as well as distinct patterns of transcription of carotenogenic enzymes within the seven orange-coloured cultivars. In one cultivar, 'Fogo', carrying the mutant ccs-3 allele, transcripts were detected for this gene, but no CCS protein accumulated. The premature stop termination in ccs-3 prevented expression of the biosynthetic activity to synthesize the capsanthin and capsorubin forms of carotenoids. In two other orange-coloured cultivars, 'Orange Grande' and 'Oriole', both with wild-type versions of all four carotenogenic enzymes, no transcripts for Ccs were detected and no red pigments accumulated. Finally, in a third case, the orange-coloured cultivar, Canary, transcripts for all four of the wild-type carotenogenic enzymes were readily detected yet no CCS protein appeared to accumulate and no red carotenoids were synthesized. In the past, mutations in Psy and Ccs have been identified as the loci controlling colour in the fruit. Now there is evidence that a non-structural gene may control colour development in Capsicum.

Variability of Carotenoid Biosynthesis in Orange Colored Capsicum spp

Pepper, Capsicum spp., is a worldwide crop valued for heat, nutrition, and rich pigment content. Carotenoids, the largest group of plant pigments, function as antioxidants and as vitamin A precursors. The most abundant carotenoids in ripe pepper fruits are β-carotene, capsanthin, and capsorubin. In this study, the carotenoid composition of orange fruited Capsicum lines was defined along with the allelic variability of the biosynthetic enzymes. The carotenoid chemical profiles present in seven orange pepper varieties were determined using a novel UPLC method. The orange appearance of the fruit was due either to the accumulation of β-carotene, or in two cases, due to only the accumulation of red and yellow carotenoids. Four carotenoid biosynthetic genes, Psy, Lcyb, CrtZ-2, and Ccs were cloned and sequenced from these cultivars. This data tested the hypothesis that different alleles for specific carotenoid biosynthetic enzymes are associated with specific carotenoid profiles in orange peppers. While the coding regions within Psy and CrtZ-2 did not change in any of the lines, the genomic sequence contained introns not previously reported. Lcyb and Ccs contained no introns but did exhibit polymorphisms resulting in amino acid changes; a new Ccs variant was found. When selectively breeding for high provitamin A levels, phenotypic recurrent selection based on fruit color is not sufficient, carotenoid chemical composition should also be conducted. Based on these results, specific alleles are candidate molecular markers for selection of orange pepper lines with high β-carotene and therefore high pro-vitamin A levels.