Lutein Isomers: Preparation, Separation, Structure Elucidation, and Occurrence in 20 Medicinal Plants.

Lutein and its cis-isomers occur in a lot of plants, including a variety of flowers. In this study, lutein isomers were produced via iodine-catalyzed isomerization, and four cis-isomers (9Z-, 9'Z-, 13Z-, and 13Z') were isolated by means of column chromatography and semipreparative HPLC. The structures of the 9'Z- and 13'Z-isomers were elucidated via NMR measurements. These compounds were used as standards for the HPLC-DAD-MS determination of the carotenoid composition of the flowers of 20 plant species, in which lutein and its geometrical isomers are the main components. The flowers showed great variation in their cis- and trans-lutein content, and also in the presence or absence of other carotenoids, such as violaxanthin, neoxanthin, ß-cryptoxanthin, and ß-carotene. Some of the investigated flowers were found to be rich sources of lutein without zeaxanthin.

Effects of acute alcohol consumption on neuronal activity and cerebral vasomotor response.

INTRODUCTION: In the majority of European countries, driving after drinking small-moderate amount of alcohol is legal. Motivated by our previous studies on cerebral hemodynamics, we aimed to study whether a small-moderate blood alcohol content (BAC), at which driving is legal in some countries (0.8 g/L), influences the neuronal activity, neurovascular coupling, and cerebral vasoreactivity. METHODS: Analyses of pattern-reversal visual evoked potential (VEP) and transcranial Doppler (TCD) examinations were performed in thirty young healthy adults before and 30 min after alcohol consumption. Cerebral vasoreactivity was evaluated by breath holding test in both middle cerebral arteries. By using a visual cortex stimulation paradigm, visually evoked flow velocity response during reading was measured in both posterior cerebral arteries (PCA). RESULTS: The BAC was 0.82 g/L and 0.94 g/L 30 and 60 min after drinking alcohol, respectively. Latency of the VEP P100 wave increased after alcohol consumption. Resting absolute flow velocity values increased, whereas pulsatility indices in the PCA decreased after alcohol ingestion, indicating vasodilation of cerebral microvessels. Breath holding index and the visually evoked maximum relative flow velocity increase in the PCA and steepness of rise of the flow velocity curve were smaller after than before alcohol consumption. CONCLUSION: BAC close to a legal value at which driving is allowed in some European countries inhibited the neuronal activity and resulted in dilation of cerebral arterioles. Cerebral vasodilation may explain the decrease of cerebral vasoreactivity and might contribute to the disturbance of visually evoked flow response after alcohol consumption.

Synthesis, Pharmacokinetic Characterization and Antioxidant Capacity of Carotenoid Succinates and Their Melatonin Conjugates.

Carotenoid succinates were synthesized from hydroxy carotenoids and were coupled to a commercially available derivative of melatonin via amide bond for producing more powerful anti-oxidants and yet new hybrid lipophilic bifunctional molecules with additional therapeutic effects. The coupling reactions produced conjugates in acceptable to good yields. Succinylation increased the water solubility of the carotenoids, while the conjugation with melatonin resulted in more lipophilic derivatives. The conjugates showed self-assembly in aqueous medium and yielded relatively stable colloidal solutions in phosphate-buffered saline. Antioxidant behavior was measured with ABTS and the FRAP methods for the carotenoids, the carotenoid succinates, and the conjugates with melatonin. A strong dependence on the quality of the solvent was observed. TEAC values of the new derivatives in phosphate-buffered saline were found to be comparable to or higher than those of parent carotenoids, however, synergism was observed only in FRAP assays.

Isolation and identification of sapotexanthin 5,6-epoxide and 5,8-epoxide from red mamey (Pouteria sapota).

Two new carotenoids, sapotexanthin 5,6-epoxide and sapotexanthin 5,8-epoxide, have been isolated from the ripe fruits of red mamey (Pouteria sapota). Sapotexanthin 5,6-epoxide was also prepared by partial synthesis via epoxidation of sapotexanthin, and the (5R,6S) and (5S,6R) stereoisomers were identified by high-performance liquid chromatography-electronic circular dichroism (HPLC-ECD) analysis. Spectroscopic data of the natural and semisynthetic derivatives obtained by acid-catalyzed rearrangement of cryptocapsin 5,8-epoxide stereoisomers were compared for structural elucidation.

Study on the Synthesis, Antioxidant Properties, and Self-Assembly of Carotenoid-Flavonoid Conjugates.

Flavonoids and carotenoids possess beneficial physiological effects, such as high antioxidant capacity, anticarcinogenic, immunomodulatory, and anti-inflammatory properties, as well as protective effects against UV light. The covalent coupling of hydrophobic carotenoids with hydrophilic flavonoids, such as daidzein and chrysin, was achieved, resulting in new amphipathic structures. 7-Azidohexyl ethers of daidzein and chrysin were prepared in five steps, and their azide-alkyne [4 + 2] cycloaddition with pentynoates of 8'-apo-ß-carotenol, zeaxanthin, and capsanthin afforded carotenoid-flavonoid conjugates. The trolox-equivalent antioxidant capacity against ABTS•+ radical cation and self-assembly of the final products were examined. The 1:1 flavonoid-carotenoid hybrids generally showed higher antioxidant activity than their parent flavonoids but lower than that of the corresponding carotenoids. The diflavonoid hybrids of zeaxanthin and capsanthin, however, were found to exhibit a synergistic enhancement in antioxidant capacities. ECD (electronic circular dichroism) and UV-vis analysis of zeaxanthin-flavonoid conjugates revealed that they form different optically active J-aggregates in acetone/water and tetrahydrofuran/water mixtures depending on the solvent ratio and type of the applied aprotic polar solvent, while the capsanthin derivatives showed no self-assembly. The zeaxanthin bis-triazole conjugates with daidzein and with chrysin, differing only in the position of a phenolic hydroxyl group, showed significantly different aggregation profile upon the addition of water.

[Relevance of animal models in the development of compounds targeting multidrug resistant cancer]. / Állatmodellek szerepe a multidrogrezisztens tumorokat célzó kemoterápia fejlesztésében.

Anticancer compounds are typically identified in in vitro screens. Unfortunately, the in vitro drug sensitivity of cell lines does not reflect treatment efficiency in animal models, and neither show acceptable correlation to clinical results. While cell lines and laboratory animals can be readily "cured", the treatment of malignancies remains hampered by the multidrug resistance (MDR) of tumors. Genetically engineered mouse models (GEMMs) giving rise to spontaneous tumors offer a new possibility to characterize the evolution of drug resistance mechanisms and to target multidrug resistant cancer.

Changes in the Carotenoids of Zamia dressleri Leaves during Development.

It has been observed that the leaves of some Zamia species undergo a kind of "reverse ripening"; that is, they change from their original brown color to green during development. We assumed that this strange color change was due to the change in carotenoid composition, so we followed the changes for several weeks. The detailed carotenoid composition and content at different stages of development of the leaves was determined with HPLC-DAD focusing on the changes in red and yellow carotenoids. The total and relative amounts of red and yellow carotenoids were determined simultaneously from one measurement from a saponified and/or unsaponified extract. At the beginning of development, the concentration of red carotenoids was higher than that of the yellow ones; it decreased drastically until 22 days and continued to decrease slowly until they completely disappeared. The concentration of yellow carotenoids decreased at the beginning as well, but after 22 days it started to increase. The amount of red carotenoids started to decrease when the leaflet stopped growing. Lutein is the main component in old leaflets, which is not a red carotenoid precursor. Red carotenoids can always be found in their esterified form in the leaves. These findings support the hypothesis that red and yellow carotenoid accumulation are independent and probably have different functions in the leaflet. The strange color change was explained based on the compartmentalization of red and yellow carotenoids and on the changing activity of the enzyme capsanthin-capsorubin synthase responsible for the synthesis of red carotenoids capsorubin and capsanthin.

Carotenoid Composition of Telekia speciosa.

The carotenoid composition of the flower of Telekia speciosa was investigated for the first time by HPLC-DAD-MS. In addition to the main carotenoid lutein and its geometrical isomers, 5,6-epoxy-carotenoids, namely violaxanthin, lutein 5,6-epoxide and antheraxanthin, were detected in larger amounts. In addition, ß-carotene 5,6-epoxide and ß-carotene 5,6,5',6'-diepoxide were found, which occurs very rarely in plants. For unambigous identification, ß-carotene 5,6-epoxide and ß-carotene 5,6,5',6'-diepoxide were prepared semisynthetically, and they were characterized by 1H and 13C NMR and HPLC-CD methods.

N-(4-Substituted-benzoyl)-N'-(ß-d-glucopyranosyl)ureas as inhibitors of glycogen phosphorylase: Synthesis and evaluation by kinetic, crystallographic, and molecular modelling methods.

N-(4-Substituted-benzoyl)-N'-(ß-d-glucopyranosyl) ureas (substituents: Me, Ph, Cl, OH, OMe, NO(2), NH(2), COOH, and COOMe) were synthesised by ZnCl(2) catalysed acylation of O-peracetylated ß-d-glucopyranosyl urea as well as in reactions of O-peracetylated or O-unprotected glucopyranosylamines and acyl-isocyanates. O-deprotections were carried out by base or acid catalysed transesterifications where necessary. Kinetic studies revealed that most of these compounds were low micromolar inhibitors of rabbit muscle glycogen phosphorylase b (RMGPb). The best inhibitor was the 4-methylbenzoyl compound (K(i)=2.3µM). Crystallographic analyses of complexes of several of the compounds with RMGPb showed that the analogues exploited, together with water molecules, the available space at the ß-pocket subsite and induced a more extended shift of the 280s loop compared to RMGPb in complex with the unsubstituted benzoyl urea. The results suggest the key role of the water molecules in ligand binding and structure-based ligand design. Molecular docking study of selected inhibitors was done to show the ability of the binding affinity prediction. The binding affinity of the highest scored docked poses was calculated and correlated with experimentally measured K(i) values. Results show that correlation is high with the R-squared (R(2)) coefficient over 0.9.

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.

Sapotexanthin, an A-provitamin carotenoid from red mamey (Pouteria sapota).

From the ripe fruits of red mamey (Pouteria sapota) sapotexanthin, a new carotenoid, was identified as (all-E,5'R)-ß,κ-caroten-6'-one.

Natural Apocarotenoids and Their Synthetic Glycopeptide Conjugates Inhibit SARS-CoV-2 Replication.

The protracted global COVID-19 pandemic urges the development of new drugs against the causative agent SARS-CoV-2. The clinically used glycopeptide antibiotic, teicoplanin, emerged as a potential antiviral, and its efficacy was improved with lipophilic modifications. This prompted us to prepare new lipophilic apocarotenoid conjugates of teicoplanin, its pseudoaglycone and the related ristocetin aglycone. Their antiviral effect was tested against SARS-CoV-2 in Vero E6 cells, using a cell viability assay and quantitative PCR of the viral RNA, confirming their micromolar inhibitory activity against viral replication. Interestingly, two of the parent apocarotenoids, bixin and ß-apo-8'carotenoic acid, exerted remarkable anti-SARS-CoV-2 activity. Mechanistic studies involved cathepsin L and B, as well as the main protease 3CLPro, and the results were rationalized by computational studies. Glycopeptide conjugates show dual inhibitory action, while apocarotenoids have mostly cathepsin B and L affinity. Since teicoplanin is a marketed antibiotic and the natural bixin is an approved, cheap and widely used red colorant food additive, these readily available compounds and their conjugates as potential antivirals are worthy of further exploration.

Glucose-based spiro-heterocycles as potent inhibitors of glycogen phosphorylase.

Glucopyranosylidene-spiro-1,4,2-oxathiazoles were prepared in high yields by NBS-mediated spiro-cyclization of the corresponding glucosyl-hydroximothioates. In an effort to synthesize analogous glucopyranosylidene-spiro-1,2,4-oxadiazolines, with a nitrogen atom instead of the sulphur, attempted cyclizations resulted in aromatization of the heterocycle with opening of the pyranosyl ring. Enzymatic measurements showed that some of the glucose-based inhibitors were active in the micromolar range. The 2-naphthyl-substituted 1,4,2-oxathiazole displayed the best inhibition against RMGPb (K(i)=160 nM), among glucose-based inhibitors known to date.

Isolation and purification of acid-labile carotenoid 5,6-epoxides on modified silica gels.

INTRODUCTION: The acid-labile carotenoid 5,6-epoxides occur in all green plants and in most fruits, but their isolation or purification is complicated and expensive because they decompose on normal silica gels. Alkaline stationary phases in open column chromatography (OCC) have low capacities, which makes them unsuitable for preparative scale. OBJECTIVE: To find a simple high-capacity stationary phase for OCC that does not induce transformations of acid-labile compounds. METHODOLOGY: Commercially available silica gel was treated with aqueous sodium bicarbonate solution to neutralise its slightly acidic character, and was then washed and dried. The effect of the treated gel (named silica-9) on violaxanthin was studied. The modified gel was also applied to the OCC of different complex natural extracts (maple leaves and fruits of yellow paprika). Carotenoids were examined by HPLC-PAD both before and after chromatography on the modified gel. RESULTS: Violaxanthin decomposed rapidly on normal silica gels but not on the modified gel. Chromatography of plant extracts showed that the modified gel had a similar capacity to the untreated gel but did not effect epoxy-carotenoids, which could be separated or enriched readily on a large scale. CONCLUSION: The modified gel does not induce any transformation or decomposition of epoxy-carotenoids but still exhibits a high capacity, suggesting that it can be used in preparative organic chemistry as an additional and convenient tool in the OCC for the separation of other acid-labile compounds.

Novel design principle validated: glucopyranosylidene-spiro-oxathiazole as new nanomolar inhibitor of glycogen phosphorylase, potential antidiabetic agent.

2-Naphthyl-substituted glucopyranosylidene-spiro-oxathiazole prepared following a novel design principle was found to be the best known glucose analogue inhibitor of rabbit muscle glycogen phosphorylase b (K(i) 160 nM).

The Janus face of precarity - Securitisation of Roma mobility in the UK.

Technological developments and the free movement of people within the EU have enabled Member States to implement new geopolitical control measures to increase migration control and social sorting of undesired migrant groups. As part of a securitisation process, these measures are often expanded upon and justified in terms of economic threat that aims to restrain 'opportunist Central East European migrants', who are associated with welfare dependence and cheap labour. Although unemployed Roma migrants are exposed to social exclusion due to the stigma of 'benefit shoppers', this paper explores how current neoliberal labour market structures facilitate new securitisation processes and fuel the precarity of Roma, even if they are employed in the host country. Based on a multi-sited ethnography completed in The United Kingdom, it will be illustrated how communitarianism of Member States stratifies the moral values of migrants' labour in a manner that defines the preconditions of social inclusion of newcomers in host societies. In short, this paper argues that even for migrants who are not welfare dependent and who are self-sustaining, their social inclusion is defined by engagement in the sort of labour that is culturally acknowledged by the host society.

Pegylated liposomal formulation of doxorubicin overcomes drug resistance in a genetically engineered mouse model of breast cancer.

Success of cancer treatment is often hampered by the emergence of multidrug resistance (MDR) mediated by P-glycoprotein (ABCB1/Pgp). Doxorubicin (DOX) is recognized by Pgp and therefore it can induce therapy resistance in breast cancer patients. In this study our aim was to evaluate the susceptibility of the pegylated liposomal formulation of doxorubicin (PLD/Doxil®/Caelyx®) to MDR. We show that cells selected to be resistant to DOX are cross-resistant to PLD and PLD is also ineffective in an allograft model of doxorubicin-resistant mouse B-cell leukemia. In contrast, PLD was far more efficient than DOX as reflected by a significant increase of both relapse-free and overall survival of Brca1-/-;p53-/- mammary tumor bearing mice. Increased survival could be explained by the delayed onset of drug resistance. Consistent with the higher Pgp levels needed to confer resistance, PLD administration was able to overcome doxorubicin insensitivity of the mouse mammary tumors. Our results indicate that the favorable pharmacokinetics achieved with PLD can effectively overcome Pgp-mediated resistance, suggesting that PLD therapy could be a promising strategy for the treatment of therapy-resistant breast cancer patients.

Carotenoid Composition of the Fruit of Red Mamey (Pouteria sapota).

The detailed carotenoid analysis of red mamey (Pouteria sapota) was achieved by HPLC-DAD-MS, chemical tests, and cochromatography with authentic samples. Altogether 47 components were detected and 34 identified from the total extract or after fractionation with column chromatography. The main carotenoids were cryptocapsin, sapotexanthin, and capsanthin 5,6-epoxide. Some further minor components containing the κ-end group with or without a hydroxy group and their 5,6-epoxy precursors were identified. Some comments are made about the biosynthesis of κ-carotenoids in red mamey.

Triple jejuno-jejunal intussusception due to metastatic renal cell carcinoma.

We report on a 61-year-old man who was referred to the accident and emergency department with recurrent episodes of vomiting and diffuse abdominal pain for 1 week prior to admission. The patient also reported frequent constipation and intermittent melaena. He had undergone tumour nephrectomy for metastatic renal clear cell carcinoma 3 years before and had received sequential vascular endothelial growth factor receptor and mammalian target of rapamycin-targeted therapies. The abdominal computed tomography scan showed small bowel obstruction due to triple intussusception of the proximal jejunum and several large intra-luminal tumour masses. Intra-operative findings were five intramural masses 15 cm distal to the ligament of Treitz over a total length of 50 cm. A primary en bloc resection with an end-to-end anastomosis was carried out. The postoperative course was uneventful.

Synthesis of carotenoid-cysteine conjugates.

Isozeaxanthin under acidic conditions forms an allylic cation which reacts readily with thiol nucleophiles. With N-acetylcysteine as a nucleophile the products obtained are carotenoid-cysteine conjugates in which the amino acid moiety is attached to the carotenoid via sulphur in position 4. The water solubility of the products can be increased by deprotection of the amino group. The antioxidant activity of the products were examined on human liver cells under conditions of hydrogen-peroxide induced oxidative stress.