- Reassociation of all-trans-3,4-dihydroanhydrorhodovibrin with lh1 subunits isolated from rhodospirillum rubrum: Selective binding of all-trans isomer from mixture of cis- and trans-Isomers
-
The reassociation of carotenoids with the photosynthetic light-harvesting 1 (LH1) pigmentprotein complex has proven to be a powerful technique to investigate the function of carotenoids. We have recently investigated the reassociation of the carotenoids, spirilloxanthin (number of conjugated C=C bonds (n) = 13), anhydrorhodovibrin (n = 12), rhodopin (n = 11), and spheroidene (n = 10)) with carotenoid-depleted LH1 subunits isolated from Rhodospirillum rubrum. In the case of the rhodopin complex, small anomalies were observed in the absorption maximum of the Qy band of bacteriochlorophyll a (BChl a Qy) and the singletsinglet energy-transter efficiency of 1carotenoid 1BChl a within the LH1carotenoid complex. The reason for these anomalies could probably be ascribed to the rhodopin hydroxy group. To investigate this further, reassociation experiments of the LH1 complex with hydroxy-protected rhodopin, all-trans-3,4-dihydroanhydrorhodovibrin (1), were conducted. We observed a normal absorption maximum (883 nm) of the BChl a Qy band in the LH11 complex. The energy-transter efficiency of 1carotenoid (11)1BChl a was found to be 53%, giving a good correlation with the other carotenoids. Furthermore, we found a preferential complexation of alltrans- 1 to carotenoid-depleted LH1 from a 1:1 mixture of all-trans-1 and cis-1 (cis-1 consists of a 1:1 mixture of 5-cis-5- trans-1 and 5-trans-5-cis-1).
- Yamamoto, Mai,Horibe, Tomoko,Nishisaka, Yoshiaki,Suzuki, Shuichi,Kozaki, Masatoshi,Fujii, Ritsuko,Doe, Matsumi,Nango, Mamoru,Okada, Keiji,Hashimoto, Hidek
-
-
Read Online
- METHOD FOR SYNTHESISING VITAMIN A
-
A method for preparing dehydro-cyclofarnesal from dehydro-farnesal by cyclization in the presence of an acid may include the dehydro-farnesal being obtained from the farnesal by dehydrogenation and may further includes the cyclization being carried out in the presence of an acid selected from Lewis acids, Bronstedt acids, and zeolites. The synthesis of vitamin A using this method further includes the conversion of dehydro-cyclofarnesal into vitamin A.
- -
-
-
- Method for preparing vitamin A and vitamin A ester
-
The invention provides a novel method for preparing vitamin A and vitamin A ester by taking farnesol as a raw material. The method comprises the following steps: carrying out oxidation reaction on farnesol and oxygen under the action of a catalyst and a cocatalyst to generate farnesal; carrying out dehydrogenation reaction on farnesal to generate dehydrofarnesal; carrying out cyclization reactionon the dehydrofarnesal under the catalysis of acid to generate a cyclized intermediate; carrying out a reaction on the cyclized intermediate with chloroisopentenol to generate vitamin A; carrying outan esterification reaction on vitamin A to generate vitamin A ester. The method avoids the defects of an existing process, and the process line is economical and effective.
- -
-
Paragraph 0061; 0063; 0067; 0069; 0073; 0075
(2020/04/17)
-
- Synthesis of apo-13- and apo-15-lycopenoids, cleavage products of lycopene that are retinoic acid antagonists
-
Consumption of the tomato carotenoid, lycopene, has been associated with favorable health benefits. Some of lycopene's biological activity may be due to metabolites resulting from cleavage of the lycopene molecule. Because of their structural similarity to the retinoic acid receptor (RAR) antagonist, β-apo-13-carotenone, the "first half" putative oxidative cleavage products of the symmetrical lycopene have been synthesized. All transformations proceed in moderate to good yield and some with high stereochemical integrity allowing ready access to these otherwise difficult to obtain terpenoids. In particular, the methods described allow ready access to the trans isomers of citral (geranial) and pseudoionone, important flavor and fragrance compounds that are not readily available isomerically pure and are building blocks for many of the longer apolycopenoids. In addition, all of the apo-11, apo-13, and apo-15 lycopenals/lycopenones/lycopenoic acids have been prepared. These compounds have been evaluated for their effect on RAR-induced genes in cultured hepatoma cells and, much like β-apo-13-carotenone, the comparable apo-13-lycopenone and the apo-15-lycopenal behave as RAR antagonists. Furthermore, molecular modeling studies demonstrate that the apo-13-lycopenone efficiently docked into the ligand binding site of RARα. Finally, isothermal titration calorimetry studies reveal that apo-13-lycopenone acts as an antagonist of RAR by inhibiting coactivator recruitment to the receptor.
- Narayanasamy, Sureshbabu,Sun, Jian,Pavlovicz, Ryan E.,Eroglu, Abdulkerim,Rush, Cassandra E.,Sunkel, Benjamin D.,Li, Chenglong,Harrison, Earl H.,Curley, Robert W.
-
p. 1021 - 1029
(2017/05/17)
-
- Base-induced decarboxylation of polyunsaturated α-cyano acids derived from malonic acid: Synthesis of sesquiterpene nitriles and aldehydes with β-, φ-, and ψ-end groups
-
Catalytic base-induced decarboxylation of polyunsaturated α-cyano-β-methyl acids derived from malonic acid led to the corresponding nitriles 3 (Schemes 2 and 3), 6 (Scheme 5), and 9 (Scheme 6). This decarboxylation occurred with previous deconjugation of
- Dufossé, Laurent,Cartier, Dominique,Valla, Benoist,Fouillaud, Mireille,Labia, Roger,Valla, Alain
-
p. 259 - 265
(2013/03/28)
-
- Antioxidant activity of (all-E)-lycopene and synthetic apo-lycopenoids in a chemical model of oxidative stress in the gastro-intestinal tract
-
Lycopene, the main pigment of tomato, is known to have protective effects on health. Its metabolites could also be involved in these effects. Potentially bioactive lycopene metabolites namely apo-10′-lycopenol, apo-10′-lycopenal, apo-14′-lycopenol, apo-14′-lycopenal, and apo-11-lycopenoids with alcohol, carboxylic acid, aldehyde and ethyl ester terminal groups were obtained by organic synthesis as (all-E) stereoisomers using HWE condensation reactions. The ability of (all-E)-lycopene and the synthesized apo-lycopenoids to inhibit lipid peroxidation was tested in a chemical model of postprandial oxidative stress in the gastric compartment. Oxidative stress was generated by metmyoglobin, the main form of dietary iron (from red meat), which is able to catalyse the peroxidation of linoleic acid under mildly acidic conditions. In this model, apo-6′-lycopenal and apo-8′-lycopenal were better inhibitors of lipid peroxidation than (all-E)-lycopene itself. For the apo-lycopenoids, a long unsaturated chain and a terminal carboxylic acid group both favour the antioxidant activity. The short-chain apo-lycopenoic acid, apo-14′-lycopenoic acid, was shown to behave like a hydrophilic antioxidant, i.e. by reducing hypervalent iron forms of metmyoglobin. Thus, besides the polyene chain length, the terminal group of the apo-lycopenoids is expected to deeply influence the lipophilic/hydrophilic balance of the molecule (and consequently its distribution between the aqueous and lipid phases) and its affinity for the heme cavity. It can thus be concluded that the polyene chain length and terminal group are two important parameters modulating the mechanism by which apo-lycopenoids express their antioxidant activity. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Goupy, Pascale,Reynaud, Eric,Dangles, Olivier,Caris-Veyrat, Catherine
-
experimental part
p. 575 - 587
(2012/05/04)
-
- New syntheses of retinal and its acyclic analog γ-retinal by an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation. A formal route to lycopene and β-carotene
-
Since the C15 β-end-group aldehyde 10 ((β-ionylidene) acetaldehyde), an excellent intermediate in the syntheses of retinoids, can be synthesized in many ways from β-ionone, and since the corresponding acyclic C15 ψ-end-group aldehyde 5 can easily be synthesized from citral (1) (Scheme 3), we applied the C15 + C5 route to the syntheses of γ-retinal ((all-E)-8) (Scheme 3) and retinal ((all-E)-13) (Scheme 4), and therefore, by coupling (2 x C20 → C 40), to the preparation of lycopene (14) and β-carotene (15) (Scheme 5). Our new syntheses of retinal ((all-E)-13) and γ-retinal ((all-E)-8 use an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation.
- Valla, Alain,Valla, Benoist,Le Guillou, Regis,Cartier, Dominique,Dufosse, Laurent,Labia, Roger
-
p. 512 - 520
(2008/02/07)
-
- Cleavage Products of Lycopene Produced by in Vitro Oxidations: Characterization and Mechanisms of Formation
-
The aim of this study was to produce in vitro oxidation products of lycopene, which could be possible in vivo metabolites. An oxidation of lycopene with potassium permanganate gave a range of lycopene degradation compounds resulting from the oxidative cleavage of one or two carbon-carbon double bonds. Eleven apo-lycopenals/ones and six apo-carotendials were obtained and tentatively characterized by HPLC-DAD-MS. Apo-11-lycopenal and apo-8,6′-carotendial were isolated and characterized by 1H NMR for the first time. Lycopene was submitted to an oxidation by atmospheric oxygen catalyzed by a metalloporphyrin, a model system of the active center of cytochrome P450 enzymes. (Z)-Isomers, monoxides, and cleavage compounds of (E)-lycopene were formed. We propose a mechanism of oxidation of lycopene by this system.
- Caris-Veyrat, Catherine,Schmid, Antje,Carail, Michel,Boehm, Volker
-
p. 7318 - 7325
(2007/10/03)
-
- Prenylation reaction performed with catalytically generated potassium prenal dienolate
-
A new prenylation method based on the reaction of catalytically generated potassium dienolate of prenal with α,β-unsaturated aldehydes is described. The reaction is highly regioselective, via a γ-1,2-addition, and provides an efficient route to retinal.
- Cahard, Dominique,Duhamel, Lucette,Lecomte, Sandrine,Poirier, Jean-Marie
-
p. 1399 - 1401
(2007/10/03)
-
- Palladium-catalysed vinylation of tertiary allylic alcohols: A new protocol for the synthesis of isoprenoid aldehydes.
-
Heck vinylation of tertiary allylic alcohols with iodo-acetal Ic, followed by an acid catalysed acetal hydrolysis-dehydration reaction, furnished isoprenoid aldehydes regioselectively in high yields.
- Bienayme,Yezeguelian
-
p. 3389 - 3396
(2007/10/02)
-
- Polyunsaturated aldehydes by direct polyvinylogation of carbonyl compounds using functionalized phosphonates.
-
Carbonyl compounds are converted into polyethylenic aldehydes in a one pot reaction with the anions of phosphonates 1. followed by a mild acidic hydrolysis.
- Duhamel, Lucette,Guillemont, Jerome,Gallic, Yann Le,Ple, Gerard,Poirier, Jean-Marie,et al.
-
p. 3129 - 3132
(2007/10/02)
-