Carotene Isomers Research Articles

Exploring the Bioactive Properties and Therapeutic Benefits of Pear Pomace.

The fruit juice industry generates a significant amount of waste, with a strong impact on the environment and the economy. Therefore, researchers have been focusing on the characterization of resources considered as food waste. This work provides information about the lipophilic and polar metabolites of pear pomace flours (PPFs) as a tool that can shed more light on the bioactive potential of this residue. Using UPLC-PDA, UPLC-FLR, and GC-MS, the study identified and quantified PPF's polar and non-polar metabolites. Essential, conditional, and non-essential amino acids were found, with asparagine being the most abundant. Isoprenoids, including lutein, zeaxanthin, and carotene isomers, ranged from 10.8 to 22.9 mg/100 g dw. Total flavonoids and phenolic compounds were 520.5-636.4 mg/100 g dw and 536.9-660.1 mg/100 g dw, respectively. Tocotrienols and tocopherols were identified, with concentrations of 173.1-347.0 mg/100 g dw and 468.7-913.4 mg/100 g dw. Fatty acids were the major non-polar compounds. All fractions significantly reduced matrix metalloproteinase-9 (MMP-9) activity. Although PPF had lower antioxidant potential (3-6 mmol Trolox/100 g dw), it inhibited AChE and BuChE by 23-30% compared to physostigmine salicylate. These findings suggest that pear pomace waste can be repurposed into functional products with valuable bioactive properties by re-introducing it in the food chain.

Tuning Single-Molecule Conductance by Controlled Electric Field-Induced trans-to-cis Isomerisation

External electric fields (EEFs) have proven to be very efficient in catalysing chemical reactions, even those inaccessible via wet-chemical synthesis. At the single-molecule level, oriented EEFs have been successfully used to promote in situ single-molecule reactions in the absence of chemical catalysts. Here, we elucidate the effect of an EEFs on the structure and conductance of a molecular junction. Employing scanning tunnelling microscopy break junction (STM-BJ) experiments, we form and electrically characterize single-molecule junctions of two tetramethyl carotene isomers. Two discrete conductance signatures show up more prominently at low and high applied voltages which are univocally ascribed to the trans and cis isomers of the carotenoid, respectively. The difference in conductance between both cis-/trans- isomers is in concordance with previous predictions considering π-quantum interference due to the presence of a single gauche defect in the trans isomer. Electronic structure calculations suggest that the electric field polarizes the molecule and mixes the excited states. The mixed states have a (spectroscopically) allowed transition and, therefore, can both promote the cis-isomerization of the molecule and participate in electron transport. Our work opens new routes for the in situ control of isomerisation reactions in single-molecule contacts.

Effect of oxygen on isomerization of β-carotene during thermal treatment

Abstract All- trans -β-carotene was isomerized by heating, and followed by degradation. The isomers produced with and without oxygen identified were 15-cis-, 13-cis-, and 9-cis-β-carotene. The presence of oxygen accelerated the isomerization of all- trans -β-carotene more rapidly in the initial heating period than that in absence of oxygen. After 30 min heating, more than 90% of all- trans -β-carotene and its isomers were destroyed with and without oxygen. The changing patterns of content and proportion of carotene isomers during heating were not different from each other regardless of the presence of oxygen.

Simultaneous analysis of carotenoids and tocopherols in botanical species using one step solid–liquid extraction followed by high performance liquid chromatography

Carotenoids and tocopherols from botanical species abundant in Atlantic mountain grasslands were simultaneously extracted using one-step solid–liquid phase. A single n-hexane/2-propanol extract containing both types of compounds was injected twice under two different sets of HPLC conditions to separate the tocopherols by normal-phase chromatography and carotenoids by reverse-phase mode. The method allowed reproducible quantification in plant samples of very low amounts of α-, β-, γ- and δ-tocopherols (LOD from 0.0379 to 0.0720μgg−1 DM) and over 15 different xanthophylls and carotene isomers. The simplified one-step extraction without saponification significantly increased the recovery of tocopherols and carotenoids, thereby enabling the determination of α-tocopherol acetate in plant samples. The two different sets of chromatographic analysis provided near baseline separation of individual compounds without interference from other lipid compounds extracted from plants, and a very sensitive and accurate detection of tocopherols and carotenoids. The detection of minor individual components in botanical species from grasslands is nowadays of high interest in searching for biomarkers for foods derived from grazing animals.

Effect of processing conditions on the content of cis/trans carotene isomers as provitamin A carotenoids in Korean sweet potato varieties

The present investigation intends to evaluate the changes in the content of cis/trans carotene isomers as provitamin A carotenoids by steaming and roasting processes in the roots of four Korean sweet potato varieties viz. Shinzami, Younwhangmi, Chuwhangmi and Jinhongmi using a liquid chromatography with diode array detection and the negative ion atmospheric pressure chemical ionization mass spectrometric (LC-DAD-APCI/MS) method and UV spectral pattern library created from several reference data. Except Shinzami, the content of all trans β-carotenes was found to slightly decreased or remained constant when steamed or roasted. The content of cis α-/β-carotenes was potentially increased about 2-fold or greater when raw or steamed and the content was slightly decreased while roasted. In Chuwhangmi, the content of 13-cis α-carotene and all trans α-carotenes were rapidly increased when steamed and slightly decreased when roasted. Chuwhangmi exhibited 27.2 mg/100 g DW content of all trans β-carotenes when roasted and thus, it was considered as a relatively superior cultivar.

Studies of Carotene Extraction from Sweet Potato Variety CYY95-26, Ipomoea batatas, L

The goal of this study was to extract β-carotene from CYY95-26 sweet potatoes. Acetone was used as the solvent to successfully extract β-carotene. To achieve better extraction results, acetone concentration was required to be higher than 75%. Two extraction parameters, including acetone concentration and extraction time, were evaluated with the response surface methodology. The process was optimized, and optimal extraction conditions were determined to be 91.1% of acetone and 19.6 min extraction. Acetone concentration was a significant factor of the β-carotene extraction. The multiple extraction improved the extraction performance. After the third extraction, 278.1 mg/kg of β-carotene was extracted. The major carotene of CYY95-26 sweet potatoes was all-trans-β-carotene. CYY95-26 also contained small amount of 9-cis-β-carotene and 13-cis-β-carotene which were carotene isomers.

Effect of Storage and Cooking on β-Carotene Isomers in Carrots (Daucus carota L. cv. ‘Stefano’)

Carrots are one of the highest dietary sources of beta-carotene and are naturally high in the (all-E)-beta-carotene isomer, which has higher bioavailability, provitamin A activity, and antioxidant capacity compared to Z (cis) isomers. The objectives of the present study were to investigate the effects of storage temperature, time, and cooking (boiling for 15 min) on the levels of carotene isomers in 'Stefano' carrots. Storing carrots at either 4 degrees C to simulate long-term storage or 20 degrees C to simulate marketing practices resulted in increases in (all-E)-beta-carotene of 20.3% after 3 days at 4 degrees C and 34.4% after 14 days at 20 degrees C, respectively. The levels of Z isomers in raw carrots were low with (13Z)-beta-carotene and (9Z)-beta-carotene accounting for less that 1.8% of the total beta-carotene present. Levels of (9Z)-beta-carotene decreased during storage at either temperature, whereas storage at 4 degrees C resulted in a 109% increase in (13Z)-beta-carotene after 56 days. Cooking significantly increased the levels of (13Z)-beta-carotene and (9Z)-beta-carotene and resulted in the production of (15Z)-beta-carotene, which was absent in raw carrots. Storage at 4 degrees C for 15 days or more prior to cooking reduced the susceptibility of (all-E)-beta-carotene to thermal isomerization during cooking, resulting in lower levels of all three Z-beta-carotene isomers being generated, while storage at 20 degrees C for up to 21 days resulted in significantly higher levels of (all-E)-beta-carotene before and after cooking but had no effect on Z-isomer production during cooking. Consequently, we conclude that, for the greatest health benefit, fresh carrots can be stored for up to 21 days at 20 degrees C or at 4 degrees C for up to 56 days without significant reduction in (all-E)-beta-carotene and should be consumed raw or boiled for less than 15 min to limit Z-beta-carotene isomer formation.

Theoretical study of the low-lying excited states of [formula omitted]-carotene isomers by a multireference configuration interaction method

The combined density functional theory and multireference configuration interaction method (DFT/MRCI) has been employed to explore the ground and low-lying electronically excited states of various β -carotene monocis and dicis isomers. Although the excitation energies are generally somewhat underestimated by DFT/MRCI, the experimental trends are well reproduced and allow an interpretation of the main bands of the UV–Vis spectra. The optically bright signal is correctly assigned to S 0 → S 2 , corresponding to the HOMO → LUMO transition, whereas the so-called cis-band originates mainly from the S 0 → S 4 transition and arises from HOMO−1 → LUMO and HOMO → LUMO+1 excitations. The calculations reveal a correlation between the oscillator strengths of these transitions and the C6–C6′ distance thus explaining the effect of the molecular configuration on the shape of the UV–Vis spectra.

A simplified method for the HPLC resolution of alpha-carotene and beta-carotene (trans and cis) isomers.

A new HPLC/DAD (Diode Array Detector) method is proposed for the identification of some carotene isomers. The operating conditions adopted permit the resolution of alpha-carotene, all-trans-beta-carotene, 9-cis-beta-carotene, 13-cis-beta-carotene and 15-cis-beta-carotene. Moreover, the chromatographic conditions reported are simplified in respect of those reported up to now. The method is applied to the determination of carotenoids in a dried Dunaliella salina extract, but it could be also applied to other organic matrices such as eggs.

Relative reactivity of vitamin A versus a mixture of β-carotene geometric isomers with electrochemically generated superoxide and hydroperoxyl radicals

The present study comprises a kinetic comparison of the reactivity of electrochemically generated superoxide, O 2 − , and hydroperoxyl, HO 2 , radicals toward a mixture of β -carotene geometric isomers versus all - trans -retinol (vitamin A). Rate constants were determined by computer simulation of experimental cyclic voltammetric data. It is reported that all - trans -retinol reacts more readily with both O 2 − and HO 2 than a mixture of geometric β -carotene isomers. Specifically, the latter is unreactive at ≤25 mM with O 2 − within the timescale of cyclic voltammetry, while it reacts with HO 2 at least an order of magnitude slower than all - trans -retinol. Our results indicate that all - trans -retinol is a better radical scavenger than a mixture of geometric β -carotene isomers and parallel the results of a recent epidemiological study which has shown that vitamin A may be a better anticarcinogenic agent than β -carotene.

Influence of salicylic acid on H2O2 production, oxidative stress, and H2O2-metabolizing enzymes. Salicylic acid-mediated oxidative damage requires H2O2.

We investigated how salicylic acid (SA) enhances H2O2 and the relative significance of SA-enhanced H2O2 in Arabidopsis thaliana. SA treatments enhanced H2O2 production, lipid peroxidation, and oxidative damage to proteins, and resulted in the formation of chlorophyll and carotene isomers. SA-enhanced H2O2 levels were related to increased activities of Cu,Zn-superoxide dismutase and were independent of changes in catalase and ascorbate peroxidase activities. Prolonging SA treatments inactivated catalase and ascorbate peroxidase and resulted in phytotoxic symptoms, suggesting that inactivation of H2O2-degrading enzymes serves as an indicator of hypersensitive cell death. Treatment of leaves with H2O2 alone failed to invoke SA-mediated events. Although leaves treated with H2O2 accumulated in vivo H2O2 by 2-fold compared with leaves treated with SA, the damage to membranes and proteins was significantly less, indicating that SA can cause greater damage than H2O2. However, pretreatment of leaves with dimethylthiourea, a trap for H2O2, reduced SA-induced lipid peroxidation, indicating that SA requires H2O2 to initiate oxidative damage. The relative significance of the interaction among SA, H2O2, and H2O2-metabolizing enzymes with oxidative damage and cell death is discussed.

Serum response of all-trans and 9-cis isomers of beta-carotene in humans.

Little work has been performed on the serum response of various carotene isomers. The present study was carried out to examine the serum response of all-trans and 9-cis isomers of beta-carotene (BC) using frequent blood sample collections at early time points. Serum responses of all-trans BC and a mixture of BC isomers containing 80% 9-cis BC were studied in 15 men by measuring the serum concentrations of BC at 1, 3, 5, 7, 9, 12, and 24 hours after a single large oral dose of all-trans BC or 9-cis BC. The serum response to an oral dose of all-trans BC (120 mg) significantly increased from baseline at 24 hr (p < 0.004). After an oral dose of a mixture of BC isomers (120 mg, 80% 9-cis BC), the peak concentration of 9-cis BC was significantly greater that baseline values (p < 0.016). Increases in serum all-trans BC levels, in part, may be due to greater intestinal absorption, whereas the inability to measure a significant increase in the concentration of 9-cis BC may indicate poor absorption, isomerization to all-trans BC, or a very rapid tissue uptake.

ESTUDOS SOBRE CAROTENÓIDES COM ATIVIDADE DE PROVITAMINA "A" EM CULTIVARES DE MANDIOCA (Manihot esculentaCRANTZ) EM ECOSSISTEMA DE TERRA FIRME DE MANAUS, AMAZONAS, BRASIL.

Foram conduzidos experimentos de competição entre cultivares de mandioca (Manihot esculentaCrantz) em ecossistema de terra firme (Manaus - Amazonas), com objetivo de obter melhores cultivares de mandioca com relação a produtividade e teor de caroteno pró-vitamínico A. Raízes de sete cultivares de mandioca amarela foram selecionadas para identificação e quantificação de carotenos com atividade de vitamina A, mediante o método descrito por Rodriguez. Observou-se, também, as perdas de pró-vitamina A pelo processamento e armazenamento de farinha. Constatou-se a presença de três isômeros do β - caroteno (o 13 - eis -β - caroteno, o β - caroteno todo trans e o 9 - eis -β - caroteno U). Quanto aos teores de vitamina A, expressos em equivalente de retinol, nas raízes variaram de 4,4 a 18,8. Com relação a perda de atividade da vitamina A pelo processamento variou de 25,0 a 40,0 %, enquanto que o armazenamento por 6 meses em sacos plásticos transparentes, à temperatura ambiente e à exposição de luz, resultou em degradação total de seus carotenóides. Os resultados permitem concluir que três cultivares (IM 232; IM 104 e BGM 021) apresentaram os maiores teores de pró-vitamina A.

HPLC Separation of Geometric Carotene Isomers Using a Calcium Hydroxide Stationary Phase

HPLC methodology employing a calcium hydroxide stationary phase selective for separations of phytofluene, ζ-carotene, γ-carotene, α-carotene, and β-carotene geometric isomer sets was developed. The retention behavior of certain members of these isomer sets and the resulting impact of modifier selection and concentration was demonstrated. Pertinent modifications for specific analytical situations are recommended. Individual purified carotenoids were isomerized by iodine catalysis. Resolution of phytofluene isomers was achieved using hexane, that of α-carotenes using 0.1% p-methylanisole in hexane, that of β-carotenes using 2.0% p-methylanisole in hexane, that of ζ-carotenes using 1.4% benzyl ether in hexane, and that of γ-carotenes using 2.45% benzyl ether in hexane. Retention characteristics on calcium hydroxide and electronic absorption spectra allowed assignment of geometric configurations to some of the resolved peaks. These methods may be used, with modifications where necessary, to analyze isomeric sets of carotenes and to isolate individual isomers.

Optimization of mobile phases for HPLC of cis-trans carotene isomers

Various methanol-based, binary and ternary solvent systems were compared with respect to resolution of cis isomers of α and β-carotene by reversed-phase HPLC. A ternary system: acetonitrile-methanol-methylene chloride (75∶15∶10), or a binary system: acetonitrilemethanol (90∶10 or 5∶95) provided the best separation of β-carotene and its four cis isomers, 9-cis, 13-cis, 15-cis and 13,15-di-cis-β-carotene. The elution order of 9-cis and 13-cis-β-carotene was dependent on the methanol concentration. Methanol-methylene chloride (99∶1) resolved α-carotene and its three cis isomers, 9-cis, 13-cis, and 15-cis-α-carotene. It also proved the best for simultaneous separation of cis isomers of α and β-carotene. Sample solvent can affect the separation efficiency of each isomer. The presence of cis isomers of α and β-carotene in fresh and cooked carrots was also determined.

Differential Reactivity of [beta]-Carotene Isomers from Dunaliella bardawil Toward Oxygen Radicals.

Dunaliella bardawil accumulates massive amounts of [beta]-carotene in two isoforms, a 9-cis and an all-trans stereoisomer, when grown under high irradiance, as a means to protect the cells against photoinhibition (A. Ben-Amotz, A. Shaish, M. Avron [1989] Plant Physiol 91: 1040-1043). The purpose of this work has been to find out if the mechanism of protection involves scavenging of reactive oxygen species. For this purpose high- and low-[beta]-carotene-containing cells were compared with respect to their sensitivity to several external oxidants [H2O2, methyl viologen, rose bengal, and 2,2[prime]-azobis(2-amidinopropane)HCl]. All oxidants induce a light-stimulated degradation of [beta]-carotene and of chlorophyll. The degradation of [beta]-carotene precedes that of chlorophyll, indicating that it is more reactive toward oxidants. The 9-cis [beta]-carotene is degraded faster than the all-trans stereoisomer when exposed to oxidants, both in intact cells and in isolated [beta]-carotene globules, indicating that it is a more effective scavenger of reactive oxygen species. Comparison of the sensitivity to different oxidants, between high- and low-[beta]-carotene-containing cells, reveals similar rates of chlorophyll and [beta]-carotene degradation in the two populations. Survival tests toward H2O2 and rose bengal show that high-[beta]-carotene cells have a similar sensitivity toward H2O2 but are more resistant toward rose bengal, a photoactivated generator of singlet oxygen, possibly due to masking of the latter by [beta]-carotene. These results suggest that the protection mechanism of massively accumulated [beta]-carotene in Dunaliella against photoinhibition is not due to scavenging of reactive oxygen species.

Comparison of Liquid Chromatographic Methods for Determination of Cis-Trans Isomers of β-Carotene

Abstract Four liquid chromatographic columns and various solvent systems were evaluated for their ability to resolve and quantitate cls-trans Isomers of β-carotene. The Vydac C18 201 TP and Ca(OH)2 columns were most effective in resolving alltrans-, 13-cls-, and 9-cls-β-carotenes. Additionally, the 15- c18 Isomer was separated using the method employing a Ca(OH)2 column. Peak Identification was based on absorption spectra (obtained from photodlode array data), retention times, and coelutlon in comparison to authentic standards. A quantitative analysis of vegetable extracts using both the Vydac and Ca(OH)2 columns showed comparable results. However, both procedures lacked complete resolution of 2 minor clsβ-carotenes, tentatively identified as dl-cis Isomers. High selectivity for carotene Isomers as well as fewer interferences were observed with the Ca(OH)2 procedure for analysis of plant tissue extracts and thus, It is preferred for determination of β-carotene cis-isomer content In these samples.

HPLC Separation of Cis‐Trans Carotene Isomers in Fresh and Processed Fruits and Vegetables

ABSTRACTResolution of cis‐trans alpha‐ and beta‐carotene isomers was achieved using a rapid (30 min) high‐performance liquid chromatography method employing a slurry‐packed calcium hydroxide column. The isomers found in fruit and vegetable products were identical to those formed through iodine catalyzed isomerization of carotene solutions. A survey of fresh and commercially processed fruit and vegetable products indicated that the greatest percentage of isomers was found in processed foods (20.1–54.0%). Of the fresh products surveyed, cis‐isomers were found in plums, nectarines and peaches, and no cis‐isomers were detected in sweet potatoes, carrots and tomatoes; however, all fresh green vegetables contained from 19.6–28.3% monocis‐isomers.

Detection of cis-trans carotene isomers by two-dimensional thin-layer and high-performance liquid chromatography

Detection of cis-trans carotene isomers by two-dimensional thin-layer and high-performance liquid chromatography

Studio sui pigmenti liposolubili diSternbergia luteaKer-Gawl durante alcune fasi del suo ciclo biologico

Abstract A study of Sternbergia lutea Ker-Gawl lipidsoluble pigments during some phases of its biological cycle. — In the present paper we have examined the pigments of Sternbergia lutea and their variations during some particular phases of its biological cycle in order to obtain useful information on their probable function in the plant. Therefore, we have analyzed the pigments of the leaves, floral scape, tepals and anthers. The results obtained show that Sternbergia lutea is characterized by the same pigment composition as that of the other higher plants. In addition to this, three further carotenoids have been observed (mainly in the tepals and anthers). Chromatographic and spectrophotometric properties of these new pigments indicate their relationship with carotene isomers that have already been examined. During the phases of vegetative cycle of Sternbergia lutea chlorophylls and carotenoids increase concomitantly with the growth of the plant. Carotenes reach a significant maximum value only in anthers. In the course of the necrosis (that obviously occurs in different stages for the various organs) is observed a higher decrease of chlorophylls (in the green tissues) and of the carotenes (in the anthers) while lutein and violaxanthin increase greatly (in the tepals).