Hydrophilic Carotenoids Research Articles

Transcriptome-wide Characterization of Novel WRKY Family Genes Engaged in Crocin Biosynthesis in Crocus sativus

Crocins comprise a family of hydrophilic carotenoids with pharmacological properties that are produced in significant quantities in stigma of Crocus sativus. Although the biosynthesis pathway of crocins has been sufficiently elucidated, there is a paucity of information regarding how transcription factors (TFs) regulate crocin biosynthesis in various stigma developmental stages. WRKY TFs play a role in modulating carotenoid/apocarotenoid metabolism. To provide an overview of the WRKY family in Crocus sativus (CsWRKY) and characterize candidate CsWRKY TFs involved in the biosynthesis of crocins, CsWRKY genes were identified from RNA-sequenced stigma at different developmental stages. A phylogenetic analysis was performed to characterize their evolutionary interrelatedness. A coexpression analysis of CsWRKY genes and crocin biosynthesis-related genes was performed. A quantitative real-time polymerase chain reaction was used to corroborate the expression level of CsWRKY TFs in various tissue and at different developmental stages. A total of 34 CsWRKY TFs were identified from the stigma of C. sativus. The CsWRKY TFs, together with their orthologs from Arabidopsis, were clustered into group I, II, or III following phylogenetic analysis. A correlation analysis revealed that the expressions of the TFs CsWRKY1, CsWRKY2, CsWRKY8, CsWRKY10, CsWRKY15, and CsWRKY28 were strongly related to the expression of crocin biosynthesis-related genes CsBCH, CsCCD2L, CsALDH, and CsUGT. CsWRKY2, CsWRKY15, and CsWRKY28 exhibited identical motifs and were stratified into group IId. Transcript levels of candidate CsWRKY genes were higher in stigma than in other tissues and were proportional to the crocin content.

Characterization of Carotenoids Content and Composition of Saffron from Different Localities

The most essential carotenoids for humans are found in plants that are normally yellow, orange, and red coloured pigments. They are typically and mostly lipophilic in nature, but some unique plant species may yield water-soluble carotenoids. Saffron or Crocus sativus contains hydrophilic carotenoids named crocin. Thus, this paper will describe the extraction and characterization of hydrophilic and lipophilic carotenoids (colour properties) obtained from saffrons of different geographical origins. They are specifically the Iranian, Turkish, and Kashmiri saffron respectively. Maceration techniques have been employed to extract the targeted compounds, whereas the characterization of the compounds has been analysed using HPLC. The extraction and characterization of carotenoids in saffron from different geographical origins found that the amount of crocin content was substantially higher in Iranian saffron, which was 11414.67 ± 516.34 µg/g DW followed by Turkish and Kashmiri saffron. Lipohilic carotenoids (i.e. crocetin, β-carotene, and zeaxanthin) were detectable in Iranian and Turkish saffron but absent in Kashmiri saffron. Similarly, the highest amount of crocetin content was found in Iranian saffron at 1054.73 ± 50.31 µg/g DW, while the highest amount of β-carotene and zeaxanthin was found in Turkish saffron at 512.92 ± 79.98 µg/g DW and 252.04 ± 60.34 µg/g DW, respectively. There was a marked difference in carotenoid composition sourced from different localities. Various environmental factors like climatic conditions, agricultural practices, stigma separation, and storing and drying processes may play an important role to explain such difference.

Antidementia effects, metabolic profiles and pharmacokinetics of GJ-4, a crocin-rich botanical candidate from Gardeniae fructus.

Crocins, a series of hydrophilic carotenoids that are either mono- or di-glycosyl polyene esters of crocetin extracted from dried saffron stigma or fruits of gardenia, are attracting much attention due to their wide range of pharmacological effects. In our previous study, GJ-4, a mixture of crocin analogues, was obtained and derived from gardenia fruits. Mainly 18 crocin analogues were identified from GJ-4 and found to exhibit neuroprotective effects in in vitro and in vivo models. In this present study, we continue to investigate the therapeutic effects of GJ-4 on learning and memory impairments in a 2VO-induced VaD model, and the potential mechanism. In addition, the metabolic profiles and pharmacokinetic properties of GJ-4 were determined using liquid chromatography-electrospray ionization-mass spectrometry after single and multiple oral doses. All these findings presented here will serve as a solid basis to develop GJ-4 as a new therapeutic agent for dementia.

Hydrophilic Carotenoids: Recent Progress

Carotenoids are substantially hydrophobic antioxidants. Hydrophobicity is this context is rather a disadvantage, because their utilization in medicine as antioxidants or in food chemistry as colorants would require some water dispersibility for their effective uptake or use in many other ways. In the past 15 years several attempts were made to synthetize partially hydrophilic carotenoids. This review compiles the recently synthetized hydrophilic carotenoid derivatives.

Hydrophilic Carotenoids: Surface Properties and Aggregation Behavior of the Potassium Salt of the Highly Unsaturated Diacid Norbixin

AbstractThe oft‐claimed ‘good’ water solubility of the food color norbixin (3) could not be confirmed. In contrast, the potassium salt 5 of norbixin formed suitable dispersions. The surface and aggregation properties of salt 5 were investigated and compared with other naturally occurring and synthetic hydrophilic carotenoids (Table).

Hydrophilic carotenoids: facile syntheses of carotenoid oxime hydrochlorides as long-chain, highly unsaturated cationic (bola)amphiphiles

Stable cationic carotenoid aggregates — predominantly of the J-type — develop when the hydrochlorides of carotenoid aldoximes and ketoximes are exposed to water. The oxime hydrochlorides are obtained by simple syntheses from commercially available food color carotenoids. Bluish-purple, unstable transient compounds were observed during hydrochlorination performed at liquid nitrogen temperature.

Facile method for spectroscopic examination of radical ions of hydrophilic carotenoids

Hydrophilic carotenoids, unusual members of an intrinsically hydrophobic family, and their radical ions are important reactants. An all-optical method for generating singly charged radical ions of a hydrophilic carotenoid (Car) is described. It relies on photolyzing an aqueous mixture of Car and a photoionizable auxiliary solute (A), and making conditions conducive to the capture, by Car, of the hydrated electron (e(aq)(-)) or the positive hole in A(*)(+) or both. When A is Trolox (TOH), only e(aq)(-) can be captured, since TOH (*)(+) deprotonates too rapidly to be a hole donor; when A is Trolox methyl ether (TOMe), both Car(*)(-) and Car(*)(+) are formed, since TOMe (+) lives long enough to transfer its positive hole to Car; formation of Car(*)(-) is prevented under aerobic conditions.

Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids

The antioxidant activities-expressed as the electron-donating properties-of five hydrophilic carotenoids (carotenoid surfactants) and three related hydrophobic carotenoids were investigated by flash photolysis. The electron-transfer rates of the carotenoids to the triplet state of the sensitizer 2-nitronaphthalene and the energy transfer rates of triplet 2-nitronaphthalene to the carotenoids were determined. The results demonstrate that the electron-donating effects of the hydrophilic and hydrophobic carotenoids were comparable when evaluated in acetonitrile. In the presence of water, however, electron transfer (i.e., antioxidant efficiency) was enhanced by a factor of four for the hydrophilic carotenoids. The increased hydrophilicity of carotenoids, therefore, could expand their antioxidant properties, thus facilitating their use as aqueous-phase radical scavengers. At the same time, it was shown that supramolecular assembly ("aggregation") of the amphiphilic carotenoids prevented electron transfer, thus deactivating the antioxidant function. Modulation of the biophysical properties of carotenoids through synthetic modification is capable of increasing the biological and medical utility of this natural class of predominantly hydrophobic antioxidant compound.

Hydrophilic carotenoids: surface properties and aggregation of an astaxanthin-lysine conjugate, a rigid, long-chain, highly unsaturated and highly water-soluble tetracationic bolaamphiphile

The surface and aggregation properties of a synthetic, highly water-soluble carotenoid, the tetracationic astaxanthin-lysine conjugate (Asly), have been examined through measurements of surface tension, optical absorption and dynamic light scattering. The following parameters were determined: critical aggregation concentration c M, surface concentration Γ, molecular area a m, free energy of adsorption and aggregation ( Δ G ad ° and Δ G M ° , respectively), and the aggregate size r H. The compound forms true monomolecular solutions in water below c M; aggregates emerge only at rather high concentrations (≥2.18 mM).

Retrometabolic Syntheses of Astaxanthin (3,3-dihydroxy-β,β-carotene-4,4-dione) Conjugates: A Novel Approach to Oral and Parenteral Cardioprotection

Disodium disuccinate astaxanthin has potent cardioprotective effects in animals, with demonstrated preclinical efficacy in the rat, rabbit, and canine models of experimental infarction. It has been effective in subchronic and acute dosing regimens after parenteral administration, and recently published data in rats demonstrate that oral cardioprotection is also readily achieved. Myocardial salvage in the canine can reach 100% with a 4-day subchronic dosing regimen; single-dose I.V. cardioprotection, when given 2 hours before experimental coronary occlusion, is on average two-thirds of that achieved with the subchronic regimen in dogs. In conscious animals, no effects on hemodynamic parameters have been observed. Recently, the beneficial properties of this prototypical astaxanthin conjugate have been extended to include second- and third-generation compounds with improved pharmacokinetic and/or potency profiles. The primary mechanism of cardioprotection appears to be antioxidant activity: potent direct scavenging of the lynchpin radical in ischemia-reperfusion injury, superoxide anion, has been documented in appropriate model systems. In addition, modulation of serum complement activity, reduction of the levels of deposition of C-reactive protein (CRP) and the membrane attack complex (MAC) in infarcted tissue, and reduction in oxidative stress markers from the arachidonic acid and linoleic acid pathways also suggest a significant anti-inflammatory component to the mechanism of cardioprotection. Favorable plasma protein binding has been demonstrated in vitro for several astaxanthin conjugates; this binding capacity overcomes the supramolecular assembly of the compounds that occurs in aqueous solution, which in itself improves the stability and shelf-life of aqueous formulations. Astaxanthin readily populates cardiac tissue after metabolic hydrolysis of both oral and parenteral administration of the astaxanthin ester derivates, providing a reservoir of cardioprotective agent with a significant half-life due to favorable ADME in mammals. Due to the well-documented safety profile of astaxanthin in humans, disodium disuccinate astaxanthin may well find clinical utility in cardiovascular applications in humans following successful completion of preclinical and clinical pharmacology and toxicology studies in animals and humans, respectively.

Sll0254 (CrtL diox ) Is a Bifunctional Lycopene Cyclase/Dioxygenase in Cyanobacteria Producing Myxoxanthophyll

Upon depletion of Sll0254 in Synechocystis sp. strain PCC 6803, cyclized carotenoids were replaced by linear, relatively hydrophilic carotenoids, and the amount of the two photosystems decreased greatly. Full segregants of the sll0254 deletion in Synechocystis were not obtained, implying that this gene is essential for survival, most likely to allow normal cell division. The N-terminal half of Sll0254 has limited similarity to the family of lycopene cyclases, has an additional dehydrogenase motif near the N terminus, and is followed by a Rieske 2Fe-2S center sequence signature. To test whether Sll0254 serves as a lycopene cyclase in Synechocystis, the corresponding gene was expressed in Escherichia coli strains that can produce lycopene or neurosporene. In the presence of Sll0254 these linear carotenoids were converted into cyclized, relatively hydrophilic pigments, with masses consistent with the introduction of two hydroxyl groups and with spectra indicative of only small changes in the number of conjugated double bonds. This suggests that Sll0254 catalyzes formation of oxygenated, cyclized carotenoids. We interpret the appearance of the hydroxyl groups in the carotenoids to be due to dioxygenase activity involving the Rieske 2Fe-2S center and the additional dehydrogenase domain. This dioxygenase activity is required in the myxoxanthophyll biosynthesis pathway, after or concomitant with cyclization on the other end of the molecule. We interpret Sll0254 to be a dual-function enzyme with both lycopene cyclase and dioxygenase activity and have named it CrtL(diox).

Hydrophilic Carotenoids: Surface Properties and Aggregation of Crocin as a Biosurfactant

The surface and aggregation properties of the naturally occurring carotenoid crocin (1), examined through measurements of surface tension and UV/VIS absorption, have been used to determine the following parameters: critical aggregate concentration, surface-saturation concentration, molecular area, free energy of adsorption and micellation, adsorption-micellar energy relationship, equilibrium constants, and aggregate size. On structural grounds and based on the determined molecular area at the interface, the digentiobiosyl ester of the conjugated, highly unsaturated carotenoid diacid crocetin C20 : 7 should be classified as a bolaamphiphile. Crocin forms true monomolecular solutions in H2O; only at rather high concentrations aggregation occurs.

Hydrophilic carotenoids: surface properties and aqueous aggregation of a rigid, long-chain, highly unsaturated dianionic bolaamphiphile with a carotenoid spacer

The water dispersibility of astaxanthin was greatly enhanced by converting it to a disodium disuccinate salt. This carotenoid salt behaved as a bolaamphiphile in water; dynamic light scattering (DLS) revealed the formation of stable aggregates with an average hydrodynamic radius close to 1 μm. Larger aggregates were observed in solutions of increased osmolarity. Absorption spectra demonstrated that the aggregates could withstand the addition of 20% acetonitrile before disintegrating to monomers. The physicochemical properties of this astaxanthin derivative in solution were comprehensively studied by measuring surface tension, critical aggregate concentration, surface concentration, molecule area, free energy of adsorption and micellation, adsorption–aggregate energy relationship, and equilibrium constants, and then compared with similar compounds reported previously in the literature.

Hydrophilic carotenoids: surface properties and aggregation behavior of a highly unsaturated carotenoid lysophospholipid

The water dispersibility of a hydrophobic carotenoid has been greatly enhanced by using it as the acyl part in the synthesis of a highly unsaturated lysophospholipid. Dynamic light scattering has revealed the formation of stable aggregates with an average hydrodynamic radius of a few nanometers, and absorption spectra show that the aggregates can withstand the addition of ethanol or acetonitrile until the volume fraction of water falls below 70 and 62%, respectively. The properties of the carotenoid phospholipids have been characterized by determining surface tension, critical micelle concentration, surface concentration, molecular area, free energy of adsorption and micellation, adsorption–micellar energy relationship, and equilibrium constants.

A direct study of the cohesion of lecithin bilayers: The effect of hopanoids and α,ω-dihydroxycarotenoids

The swelling of phospholipid unilamellar vesicles under an osmotic shock can be followed by stopped-flow transmittance measurements, which make it possible to evaluate “directly” the mechanical properties of the membrane. The double-layer membrane is reinforced by rigid “pegs” (cholesterol, hopanoids), or rigid “rivets” (distally hydrophilic carotenoids).