Zur Bildung isomerer Trihydroxy-octadecensäuren bei der enzymatischen Oxydation von Linolsäure durch Gerstenmehl

Incubation of linoleic acid with barley flour at pH 6.8 leads to the formation of three isomeric trihydroxy octadecenoic acids, namely: 9,12,13-trihydroxy-10-trans-octadecenoic acid, 9,10,13-trihydroxy-11-trans-octadecenoic acid and 9,10,11-trihydroxy-12-trans-octadecenoic acid. The acids were isolated by column chromatography using silicic acid and boric acid impregnated silicic acid and their structures were ascertained by means of IR, NMR and mass spectroscopy.

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Mit 4 Abbildungen     

Novel octulosonic acid derivatives in the composite Smallanthus sonchifolius

Two novel octulosonic acid derivatives with a 6,8-dioxabicyclo[3.2.1]octane skeleton that are major water-soluble phenolic compounds were found in the roots of Smallanthus sonchifolius. The structures of these compounds were determined to be (1R,2S,3S,4R,5S,7R)-4-hydroxy-7-hydroxymethyl-3-[3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyloxy]-6,8-dioxabicyclo[3.2.1]octan-5-carboxylic acid (4-O-caffeoyl-2,7-anhydro-d-glycero-β-d-galacto-oct-2-ulopyranosonic acid) and (1R,2S,3R,4R,5S,7R)-2,4-dihydroxy-7-hydroxymethyl-2,3-bis[3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyloxy]-6,8-dioxabicyclo[3.2.1]octan-5-carboxylic acid (4,5-di-O-caffeoyl-2,7-anhydro-d-glycero-β-d-galacto-oct-2-ulopyranosonic acid) by MS, NMR and CD spectral analyses.     

Synthetic access to arsenic-containing phosphatidylcholines

We wish to disclose the first synthesis of 1-O-hexadecanoyl-2-O-((15-(dimethylarsinoyl)pentadecanoyl)oxy)-sn-glycero-3-phosphocholine, which belongs to the group of arsenic-containing phosphatidylcholines (AsPCs), recently discovered in herring caviar. The synthesized product will serve as a model compound to study biological and toxicological properties of arsenolipids in food.     

Tritordeum as an Innovative Alternative to Wheat: A Comparative Digestion Study on Bread

Tritordeum results from the crossbreeding of a wild barley (Hordeum chilense) species with durum wheat (Triticum turgidum spp. turgidum). This hexaploid crop exhibits agronomic and rheological characteristics like soft wheat, resulting in an innovative raw material to produce baked goods. We applied a gel-based proteomic approach on refined flours to evaluate protein expression differences among two widespread tritordeum cultivars (Aucan and Bulel) taking as the reference semolina and flour derived from a durum and a soft wheat cvs, respectively. The products of in vitro digestion of model breads were analyzed to compare bio-accessibility of nutrients and mapping tritordeum bread resistant peptides. Significant differences among the protein profiles of the four flours were highlighted by electrophoresis. The amino acid bio-accessibility and the reducing sugars of tritordeum and wheat breads were comparable. Tritordeum cvs had about 15% higher alpha-amino nitrogen released at the end of the duodenal simulated digestion than soft wheat (p < 0.05). Bulel tritordeum flour, bread and digested bread had about 55% less R5-epitopes compared to the soft wheat. Differences in protein expression found between the two tritordeum cvs reflected in diverse digestion products and allergenic and celiacogenic potential of the duodenal peptides. Proteomic studies of a larger number of tritordeum cvs may be successful in selecting those with good agronomical performances and nutritional advantages.     

Studies on the Michael addition of naphthoquinones to sugar nitro olefins: first synthesis of polyhydroxylated hexahydro-11H-benzo[a]carbazole-5,6-diones and hexahydro-11bH-benzo[b]carbazole-6,11-diones

A strategy for the synthesis of the novel (6bR,7R,8S,9S,10S,10aR)-8-(benzyloxy)-7,9,10-trihydroxy-6b,7,8,9,10,10a-hexahydro-11H-benzo[a]carbazole-5,6-dione is reported. The key steps were the Michael addition of 2-hydroxy-1,4-naphthoquinone to 1-nitrocyclohexene or 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-α-d-xylo-hex-5-enefuranose and the diastereoselective intramolecular Henry reaction of 3-O-benzyl-5,6-dideoxy-5-C-(3′-hydroxy-1′,4′-naphthoquinon-2′-yl)-1,2-O-isopropylidene-6-nitro-α-d-glucofuranose to give the key (1S,2S,3S,4R,5R,6R)-3-(benzyloxy)-1,2,4-trihydroxy-5-(3′-hydroxy-1′,4′-naphthoquinon-2′-yl)-6-nitrocyclohexane. When 2-hydroxy-1,4-naphthoquinone was replaced by (1,4-dimethoxynaphthalen-2-yl)lithium, the novel (1R,2S,3S,4R,4aS,11bS)-2-(benzyloxy)-1,3,4-trihydroxy-1,2,3,4,4a,5-hexahydro-11bH-benzo[b]carbazole-6,11-dione was obtained.     

New Alk(en)ylhydroxycyclohexanes with Tyrosinase Inhibition Potential from Harpephyllum caffrum Bernh. Gum Exudate

This work presents the first report on the phytochemical investigation of Harpephyllum caffrum Bernh. gum exudate. A known cardanol, 3-heptadec-12′-Z-enyl phenol (1) and three new alk(en)ylhydroxycyclohexanes, namely, (1R,3R)-1,3-dihydroxy-3-[heptadec-12′(Z)-enyl]cyclohexane (2) (1S,2S,3S,4S,5R)-1,2,3,4,5-pentahydroxy-5-[octadec-13′(Z)-enyl]cyclohexane (3) and (1R,2S,4R)-1,2,4-trihydroxy-4-[heptadec-12′(Z)-enyl]cyclohexane (4) were isolated from the gum. The structures of the compounds were determined by extensive 1D and 2D NMR spectroscopy and HR-ESI-MS data. The ethanolic extract of the gum was found to be the most potent tyrosinase inhibitor with IC₅₀ of 11.32 µg/mL while compounds 2 and 3, with IC₅₀ values of 24.90 and 26.99 µg/mL, respectively, were found to be potential anti-tyrosinase candidates from the gum. Gum exudate may be a potential source for non-destructive harvesting of selective pharmacologically active compounds from plants. The results also provide evidence that H. caffrum gum may find application in cosmetics as a potential anti-tyrosinase agent.     

Stereoselective synthesis of (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone

A stereoselective synthesis of the pentaketide lactone (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone has been achieved.     

Effect of the Addition of Dried Dandelion Roots (Taraxacum officinale F. H. Wigg.) on Wheat Dough and Bread Properties

Dried and crushed dandelion roots (Taraxacum officinale F. H. Wigg.) (TO) were used as a formulation additive (at the amount of 0, 1, 3, 4, 5, and 6 g 100 g⁻¹ flour) to wheat bread. The farinographic properties of the dough and the physical and chemical properties of the bread were evaluated. It was found that the addition of dried flour caused a significant decrease in water absorption by the flour (1% and higher TO level), an increase in the development time (from 2% to 5% TO addition) and dough stability (3% and 4% TO level), and an increase in dough softening (4% and higher TO level). As the substitution of TO for wheat flour increased, there was a gradual decrease in loaf volume, an increase in specific weight and crumb hardness, and a darkening of the crumb color. The total polyphenol content increased linearly with the percentage increase of dried root additions TO from 0.290 to 0.394 mg GAE g⁻¹ d.m_., which translated into an increase in the antioxidant activity of the bread. It was found that dried crushed roots of Taraxacum officinale can be a recipe additive for wheat bread; however, due to their specific smell and bitter aftertaste, the level of this additive should not exceed 3 g 100 g⁻¹ flour.     

Effect of Coconut and Chestnut Flour Supplementations on Texture,Nutritional and Sensory Properties of Baked Wheat Based Bread

Wheat bread, produced by the single-phase method, is a common food consumed all over the world. Due to changes in lifestyle and nutritional trends, alternative raw materials are sought to increase the nutritional value and improve the taste of daily consumed products. Additionally, customers seek a wide variety of foods, especially when it comes to basic foods. Nuts, such as coconuts or chestnuts, might provide an attractive flavour with benefits to the nutritional quality. In this study, the effect of substituting wheat flour with coconut or chestnut flour (flour contribution level: 5, 10, 15, 30, 50% w/w), was evaluated in terms of the breads specific volume, texture, colour, nutritional composition, and dietary fibre fraction contents. Moreover, a sensory evaluation was conducted to assess potential consumer acceptance. Based on the consumer’s perception, the overall acceptance of bread with 15% w/w of coconut and chestnut flour was in privilege compared to the control sample. As a result, taking all of the tested parameters into account, the breads with 5, 10, and 15% supplementation of chestnut or coconut flour were still of good quality compared to the wheat bread and their fibre content was significantly higher.     

Synthesis of (−)‐Pinellic Acid and Its (9R,12S,13S)‐Diastereoisomer

The total synthesis of (?)‐pinellic acid with (9S,12S,13S)‐configuration and its (9R,12S,13S)‐diastereoisomer was achieved in high overall yields from a common intermediate derived from (+)‐L ‐diethyl tartrate.     

Enantiospecific synthesis of the sugar amino acid (2S,5S)-5-(aminomethyl)-tetrahydrofuran-2-carboxylic acid

An enantiospecific synthesis of the tetrahydrofuran amino acid (2S,5S)-5-(aminomethyl)-tetrahydrofuran-2-carboxylic acid 1 is reported. The sugar enone 2-(S)-octyl 6-O-acetyl-3,4-dideoxy-α-d-glycero-hex-3-enopyranosid-2-ulose 2a, derived from galactose, was employed as a chiral precursor. The enone 2a was converted by chemical manipulation of the functional groups into the 6-azido-2-O-tosyl-3,4,6-trideoxy-d-erythro-hexono-1,5-lactone 9 as key intermediate. Methanolysis of 9 induced the opening of the lactone and the attack of the hydroxyl group at C-5 to C-2 with the displacement of the tosylate. This reaction led to the formation of the tetrahydrofuran ring of methyl (2S,5S)-5-(azidomethyl)-tetrahydrofuran-2-carboxylate 10, which was readily converted into 1. The overall yield of the sequence was 35%, and all the intermediates and the final product have been fully characterized. In addition, the preferential conformations in solution of lactone 9 and target molecule 1 have been established.     

19-nor-11-Oxooleanan-12-ene and 18,19-seco-19-oxours-11,13(18)-diene triterpenes from Diospyros decandra bark

Four new triterpenes, 2α,3β-dihydroxy-19-nor-11-oxo-20-dimethylurs-12-en-24,28-dioic acid (equivalent to 2α,3β-dihydroxy-19-nor-11-oxoolean-12-en-24,28-dioic acid), 2α,3β-dihydroxy-18,19-seco-19-oxours-11,13(18)-dien-24,28-dioic acid, 2α,3β,19α-trihydroxy-11-oxours-12-en-24,28-dioic acid and 2α,3β,19α-trihydroxy-28-1′-β-d-[glucopyranosyl-(1″→6′)-glucopyranosyl]-urs-12-en-24,28-dioic acid were isolated from the methanol extract of the bark of Diospyros decandra as their acetate-methyl ester derivatives. The first two compounds represent the biosynthetic transformation products of 2α,3β,19-trihydroxyurs-24,28-dioic acid via oxidative rearrangement of ring E.     

4,4′-Dihydroxy-3,3′,5,5′-tetramethoxyazodioxybenzene: an unexpected dimer formed during hydroxylamine extractions of wheat flour

Neutral hydroxylamine extracts of wheat contained a product that was colourless at pH<5 (λ_max 340 nm) and yellow at pH>9 (λ_max 400 nm). ESI-MS showed a major ion m/z 184.0 and a possible parent ion m/z 367.2 (MH⁺) suggesting that the product resulted from the reaction of 2,6-dimethoxy-p-quinone with hydroxylamine. However, mass spectral and other spectroscopic data indicated that the compound was neither of the 2,6-dimethoxy-p-quinone oximes. A product with identical absorbance, mass spectrum, electrophoretic mobility and HPLC retention time as the pigment from hydroxylamine extracts of flour was observed amongst the reaction products of hydroxylamine and 1,4-dihydroxy-2,6-dimethoxybenzene. The structure of this product was identified by NMR, 2D NMR and IR as 4,4′-dihydroxy-3,3′,5,5′-tetramethoxyazodioxybenzene.     

Ancient Wheat and Quinoa Flours as Ingredients for Pasta Dough—Evaluation of Thermal and Rheological Properties

The aim of this study was to investigate thermal and rheological properties of selected ancient grain flours and to evaluate rheological properties of mixtures thereof represented by pasta dough and dry pasta. Flours from spelt, einkorn, and emmer ancient wheat varieties were combined with quinoa flour. All these flour sources are considered healthy grains of high bioactive component content. Research results were compared to durum wheat flour or spelt wheat flour systems. Differential scanning calorimeter (DSC) and a rapid visco analyzer (RVA) were used to investigate the phase transition behavior of the flours and pasting characteristics of the flours and dried pasta. Angular frequency sweep experiments and creep and recovery tests of the pasta dough were performed. The main components modifying the pasta dough structure were starch and water. Moreover, the proportion of the individual flours influenced the rheological properties of the dough. The durum wheat dough was characterized by the lowest values of the K′ and K″ parameters of the power law models (24,861 Pa·sⁿ′ and 10,687 Pa·sⁿ″, respectively) and the highest values of the instantaneous (J₀) and retardation (J₁) compliances (0.453 × 10⁻⁴ Pa and 0.644 × 10⁻⁴ Pa, respectively). Replacing the spelt wheat flour with the other ancient wheat flours and quinoa flour increased the proportion of elastic properties and decreased values of the J₀ and J₁ of the pasta dough. Presence of the quinoa flour increased pasting temperature (from 81.4 up to 83.3 °C) and significantly influenced pasting viscosities of the spelt wheat pasta samples. This study indicates a potential for using mixtures of spelt, einkorn, and emmer wheat flours with quinoa flour in the production of innovative pasta dough and pasta products.     

Total synthesis, elucidation of absolute stereochemistry, and adjuvant activity of trihydroxy fatty acids

Pinellic acid from the tuber of Pinellia ternate, an active herbal component of the traditional Japanese herbal (Kampo) medicine Sho-seiryu-to, is a C18 trihydroxy fatty acid whose absolute stereochemistry has now been determined. All stereoisomers of pinellic acid were synthesized via regioselective asymmetric dihydroxylation, regioselective inversion, and stereoselective reduction in order to determine their absolute stereochemistries and adjuvant activities. Among this series of isomers, the (9S,12S,13S)-compound, which is a natural product, exhibited the most potent adjuvant activity. Spectral data for all of the stereoisomers of the 1,2-allylic diols were compared and related to their stereochemistries.     

Masked constrained cysteines: diastereoselective and enantioselective synthesis of 1-amino-2-mercaptocyclopropanecarboxylic acid derivatives

A diastereoselective and enantioselective synthesis of (Z)-1-benzoylamino-2-tritylsulfanylcyclopropanecarboxylic acid derivatives 8a,b and 9a,b was achieved starting from (−)- or (+)-menthyl 2-benzoylamino-3-tritylsulfanylacrylates 3a,b. Compounds 3 were reacted with diazomethane giving the corresponding pyrazolines 4a,b and 5a,b. These compounds, on melting, were transformed, under steric control, into the cyclopropaneamino acid derivatives (R,R)-8a,b and (S,S)-9a,b. The synthesis of a large class of chiral 2-S-alkyl-1-aminocyclopropanecarboxylic acid derivatives is possible after removing the trityl protecting group and subsequent alkylation reactions.     

Stereoselective total synthesis of the (Z)-isomer of a novel phytotoxic nonenolide from Phomopsis sp. HCCB03520 and its C-6 epimer

The (Z)-isomer of a phytotoxic nonenolide, (6S,7R,9R)-6,7-dihydroxy-9-propylnon-4-eno-9-lactone isolated from Phomopsis sp. HCCB03520 and its C-6 epimer have been synthesized through a common route starting from butyraldehyde. The synthesis involves enantioselective Maruoka allylation, Sharpless asymmetric epoxidation and intramolecular ring closing metathesis as the important steps.     

The first asymmetric synthesis of all four isomers of cis- and trans-3,4-dihydroxy-3,4-dihydromollugin

Asymmetric synthesis of all the four stereoisomers of cis-3,4-dihydroxy-3,4-dihydromollugins 4 and 6 and trans-3,4-dihydroxy-3,4-dihydromollugins 5 and 7 was achieved. The O-methoxymethyl mollugin derivatives were dihydroxylated to (−)- and (+)-cis-3,4-dihydroxy-3,4-dihydromollugin derivatives using both AD-mix-α and AD-mix-β. Deprotection of the MOM-ethers of cis-dihydroxy compounds resulted in the targeted stereoisomers (−)-(3R,4R)-cis-3,4-dihydroxy-3,4-dihydromollugin 4, (−)-(3R,4S)-trans-3,4-dihydroxy-3,4-dihydromollugin 5, (+)-(3S,4S)-cis-3,4-dihydroxy-3,4-dihydromollugin 6 and (+)-(3S,4R)-trans-3,4-dihydroxy-3,4-dihydromollugin 7. These routes were paved with difficulties, for example, incompatibility of the substrates with AD-mixes, the unexpected formation of trans-dihydroxy compounds and failures in deprotection protocols.     

Synthesis of kairomones and their analogs from 2-acylcyclohexane-1,3-diones with an unsaturated acyl side chain

Natural 2-[(9Z)-1-oxooctadec-9-en-1-yl]-, 2-[(9Z,12Z)-1-oxooctadeca-9,12-dien-1-yl]-, and 2-[(9Z,12Z,15Z)-1-oxooctadeca-9,12,15-trien-1-yl]cyclohexane-1,3-diones (components of flour moth Ephestia kuehniella kairomones) and some their analogs were synthesized from cyclohexane-1,3-diones and long-chain unsaturated carboxylic acid chlorides.     

New lignans from <Emphasis Type="Italic">Syringa reticulata</Emphasis> var. <Emphasis Type="Italic">mandshurica</Emphasis>

In the search for platelet-activating-factor (PAF) antagonists, two new lignan compounds were isolated from the leaves of Syringa reticulata Hara var. mandshurica. Their structures were elucidated as (7R,8S, 8'S)-3,4,3',4'-dimethylenedioxy-8,9-dihydroxy-8.8', 7-O-9'-lignan (mandshuricol A) and (7R,8S,8'S)-3',4'methylenedioxy-4-methoxy-3,8,9-trihydroxy-8.8', 7-O-9'-lignan (mandshuricol B), Mandshuricol A and B showed antagonistic activity on PAF in the [³H] PAF receptor binding assay with IC₅₀ values of 4.8 × 10^–5 M and 3.5 × 10^–5 M, respectively.