Esterified carotenoids as new food components in cyanobacteria.

Among the nutritional properties of microalgae, this study is focused in the presence of carotenoid esters in prokaryote microalgae, an event that has not been shown so far. Three carotenoid esters that accumulate in non-stressful culture conditions are identified in Aphanotece microscopica Nägeli and Phormidum autumnale Gomont, what may provide an extra value to the quality attributes of the carotenoid profile in cyanobacteria as functional foods. In addition, new data on the carotenoid characterization added quality criteria for the identification of the esterified metabolites, enabling the monitoring of these food components. Specifically, the metabolomic approach applied to the food composition analysis, has allowed to differentiate between the esters of zeinoxanthin and ß-cryptoxanthin, which were undifferentiated to date during the MS characterization of carotenoids in other food sources. We propose a new qualifier product ion specific for zeinoxanthin ester, which it is not present in the MS2 spectrum of ß-cryptoxanthin esters.

Transformation of naturally occurring (3R,3'R,6'R)-lutein and its fatty acid esters to (3 R)-ß-cryptoxanthin and (3R,6'R)-α-cryptoxanthin.

The objective of this study was to develop straightforward processes that could be applied to the large-scale production of ß-cryptoxanthin in an attempt to facilitate investigation of its biological activity. An oleoresin obtained from crude extracts of marigold flowers (Tagetes erecta) with approximately 24% total lutein fatty acid ester content was directly used as starting material for partial synthesis of (3 R)-ß-cryptoxanthin under mild reaction conditions at ambient temperature. Therefore, acid-catalyzed deoxygenation of lutein esters from marigold oleoresin followed by hydrogenation in the presence of catalytic amount of platinum (Pt) supported on alumina (5%) at ambient temperature gave a mixture of (3 R)-ß-cryptoxanthin fatty acid esters (major) and (3 R,6'R)-α-cryptoxanthin fatty acid esters (minor). Saponification and Z-to-E isomerization of the product followed by crystallization gave a mixture of (3 R)-ß-cryptoxanthin as the major product. Similarly, acid-catalyzed hydrogenation of unesterified (3 R,3'R,6'R)-lutein with Pt/alumina in ethyl acetate gave a mixture of (3 R,6'R)-α-cryptoxanthin acetate (minor) in a one-pot reaction. Alkaline hydrolysis and Z-to-E isomerization of the mixture followed by crystallization provided (3 R)-ß-cryptoxanthin.

Substrate Specificity of Purified Recombinant Chicken ß-Carotene 9',10'-Oxygenase (BCO2).

Provitamin A carotenoids are oxidatively cleaved by ß-carotene 15,15'-dioxygenase (BCO1) at the central 15-15' double bond to form retinal (vitamin A aldehyde). Another carotenoid oxygenase, ß-carotene 9',10'-oxygenase (BCO2) catalyzes the oxidative cleavage of carotenoids at the 9'-10' bond to yield an ionone and an apo-10'-carotenoid. Previously published substrate specificity studies of BCO2 were conducted using crude lysates from bacteria or insect cells expressing recombinant BCO2. Our attempts to obtain active recombinant human BCO2 expressed in Escherichia coli were unsuccessful. We have expressed recombinant chicken BCO2 in the strain E. coli BL21-Gold (DE3) and purified the enzyme by cobalt ion affinity chromatography. Like BCO1, purified recombinant chicken BCO2 catalyzes the oxidative cleavage of the provitamin A carotenoids ß-carotene, α-carotene, and ß-cryptoxanthin. Its catalytic activity with ß-carotene as substrate is at least 10-fold lower than that of BCO1. In further contrast to BCO1, purified recombinant chicken BCO2 also catalyzes the oxidative cleavage of 9-cis-ß-carotene and the non-provitamin A carotenoids zeaxanthin and lutein, and is inactive with all-trans-lycopene and ß-apocarotenoids. Apo-10'-carotenoids were detected as enzymatic products by HPLC, and the identities were confirmed by LC-MS. Small amounts of 3-hydroxy-ß-apo-8'-carotenal were also consistently detected in BCO2-ß-cryptoxanthin reaction mixtures. With the exception of this activity with ß-cryptoxanthin, BCO2 cleaves specifically at the 9'-10' bond to produce apo-10'-carotenoids. BCO2 has been shown to function in preventing the excessive accumulation of carotenoids, and its broad substrate specificity is consistent with this.

Isolation of ß-Cryptoxanthin-epoxides, Precursors of Cryptocapsin and 3'-Deoxycapsanthin, from Red Mamey (Pouteria sapota).

From an extract of red mamey (Pouteria sapota) ß-cryptoxanthin-5,6-epoxide, ß-cryptoxanthin-5',6'-epoxide, 3'-deoxycapsanthin, and cryptocapsin were isolated and characterized by UV-vis spectroscopy, electronic circular dichroism (ECD), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). Epoxidation of ß-cryptoxanthin delivered the ß-(5'R,6'S)- and (5'S,6'R)-cryptoxanthin-5',6'-epoxides, which were identified by HPLC-ECD analysis. These carotenoids among others are quite common in the fruits of Central America, and as they are natural provitamins A, they should play an important role in the diet of the mostly vitamin A deficient population of this region.

Effect of kumquat (Fortunella crassifolia) pericarp on natural killer cell activity in vitro and in vivo.

Natural killer (NK) cells play a key role in innate immune defense against infectious disease and cancer. A reduction of NK activity is likely to be associated with increased risk of these types of disease. In this study, we investigate the activation potential of kumquat pericarp acetone fraction (KP-AF) on NK cells. It is shown to significantly increase IFN-γ production and NK cytotoxic activity in human KHYG-1 NK cells. Moreover, oral administration of KP-AF significantly improves both suppressed plasma IFN-γ levels and NK cytotoxic activity per splenocyte in restraint-stressed mice. These results indicate that raw kumquat pericarp activates NK cells in vitro and in vivo. To identify the active constituents, we also examined IFN-γ production on KHYG-1 cells by the predicted active components. Only ß-cryptoxanthin increased IFN-γ production, suggesting that NK cell activation effects of KP-AF may be caused by carotenoids such as ß-cryptoxanthin.

A 3-hydroxy ß-end group in xanthophylls is preferentially oxidized to a 3-oxo ε-end group in mammals.

We previously found that mice fed lutein accumulated its oxidative metabolites (3'-hydroxy-ε,ε-caroten-3-one and ε,ε-carotene-3,3'-dione) as major carotenoids, suggesting that mammals can convert xanthophylls to keto-carotenoids by the oxidation of hydroxyl groups. Here we elucidated the metabolic activities of mouse liver for several xanthophylls. When lutein was incubated with liver postmitochondrial fraction in the presence of NAD(+), (3'R,6'R)-3'-hydroxy-ß,ε-caroten-3-one and (6RS,3'R,6'R)-3'-hydroxy-ε,ε-caroten-3-one were produced as major oxidation products. The former accumulated only at the early stage and was assumed to be an intermediate, followed by isomerization to the latter. The configuration at the C3' and C6' of the ε-end group in lutein was retained in the two oxidation products. These results indicate that the 3-hydroxy ß-end group in lutein was preferentially oxidized to a 3-oxo ε-end group via a 3-oxo ß-end group. Other xanthophylls such as ß-cryptoxanthin and zeaxanthin, which have a 3-hydroxy ß-end group, were also oxidized in the same manner as lutein. These keto-carotenoids, derived from dietary xanthophylls, were confirmed to be present in plasma of normal human subjects, and ß,ε-caroten-3'-one was significantly increased by the ingestion of ß-cryptoxanthin. Thus, humans as well as mice have oxidative activity to convert the 3-hydroxy ß-end group of xanthophylls to a 3-oxo ε-end group.

Light-induced oxidation and isomerization of all-trans-ß-cryptoxanthin in a model system.

The oxidation and isomerization of all-trans-ß-cryptoxanthin as affected by iodine-catalysed illumination and non-iodine-catalysed illumination were studied. Seven cis-isomers and two oxidation products were separated by HPLC method using a C30 column. The identification and structural elucidation of the compounds were determined by HPLC-DAD-APCI-MS. Five compounds were identified in details for the first time, namely, ß-ß-carotene-3-one, 5,6-epoxy-ß-ß-carotene-3-one, 13,15-di-cis-, 9,13-di-cis- and 9,9'-di-cis-ß-cryptoxanthin. Sum of 13- and 13'-cis-ß-cryptoxanthin was the major cis-isomer of ß-cryptoxanthin formed, accounting for 59.0% and 30.6%, respectively. The formation of di-cis isomers may prefer in the present of iodine. 13,15-di-cis-ß-cryptoxanthin was the major di-cis-isomer of the iodine-catalysed photo-isomerization.