Ralf G. Berger

Carbohydrate esters of cinnamic acid from fruits of Physalis peruviana, Psidium guajava and Vaccinium vitis-idaea

Abstract 1-O-trans- Cinnamoyl-β- d -glucopyranosyl-(1→6)-β- d -glucopyranose was isolated from fruits of Physalis peruviana and 1-O-trans- cinnamoyl-α- l -arabinofuranosyl-(1→6)-β- d -glucopyranose was obtained from fruits of Psidium guajava . Fruits of Vaccinium vitis-idaea and P. guajava were found to be rich sources of 1-O-trans- cinnamoyl-β- d -glucopyranose .

The flavour of cape gooseberry (Physalis peruviana L.)

ZusammenfassungDie flüchtigen Inhaltsstoffe der Kapstachelbeere (Physalis peruviana L.) sind nach Flüssig/Flüssig-Extraktion und Kieselgelfraktionierung der Aromakonzentrate mittels hochauflösender Gaschromatographie und Kopplung Gaschromatographie-Massenspektrometrie charakterisiert worden. Durch gaschromatographische Sniffing-Analyse von sukzessive verdünnten Aromaextrakten sind 2-Methylbuttersäuremethylester, 2,5-Dimethyl-4-hydroxy-3(2H)-furanon und dessen Methoxyderivat, 4- und 5-Octanolid sowie β-Jonon and β-Damascenon als sensorische Schlüsselsubstanzen erkannt worden. Die nichtflüchtige Aromafraktion enthält Glucose, Fructose, Saccharose, Citronensäure und kleinere Mengen an organischen, aliphatischen und benzoiden Säuren. Bei den gebunden vorliegenden flüchtigen Komponenten dominieren Benzylalkohol, 2-Methylpropanol und 2-Methylbutanol. Die Frucht enthält, wie verschiedene Befunde indirekt belegen, größere Mengen an aktivierten Acylresten.SummaryThe volatile constituents of cape gooseberry (Physalis peruviana L.) were characterized using liquid/liquid extraction and fractionation of the flavour concentrates on silica gel, followed by high resolution gas chromatography and coupled gas chromatography — mass spectrometry. Sniffing gas chromatography of serially diluted flavour extracts showed methyl 2-methylbutyrate, 2,5-dimethyl-4-hydroxy-(2H)-furanone and its 4-methoxy derivative, 4- and 5-octanolide, β-ionone, and β-damascenone to be impact components. The non-volatile flavour fraction contained glucose, fructose, sucrose, citric acid, and smaller amounts of organic aliphatic and benzoic acids. The bound forms of volatiles were dominated by benzyl alcohol, 2-methylpropanol, and 2-methyl-butanol. The presence of significant amounts of activated acyl moieties in the fruit was indirectly concluded from various data.

Über die Biogenese von Aromastoffen bei Pflanzen und Früchten

SummaryAn increase in the ratio of surface to volume in strawberries and bananas using macerating enzymes does not result in an increase of the metabolic activities involved in aroma biosynthesis. Feeding strawberry segments with shortchain fatty acids as precursors under specific conditions causes a continuous increase of various fruit-typical aroma compounds and lasts for more than 36 h. In macerates of strawberries, upon addition of the above precursors, the biosynthesis of methyl esters of various unbranched fatty acids (C12–C18) is the most important GC-detectable change. The same maceration method applied to banana pulp yields macerates with an ester content which remains constant for some hours. A number of facts show that the enzymic commination of the fruit tissues is followed by a wound induced reorganisation of metabolic path-ways, with the principal capability to form carboxylic esters remaining for more than four days.ZusammenfassungEine Vergrößerung des Verhältnisses von Oberfläche zu Volumen durch Macerationsenzyme bei Erdbeer- und Bananenfrüchten führt nicht zu einem Anstieg der für die Aromabiosynthese verantwortlichen metabolischen Aktivitäten. Werden Erdbeersegmente unter spezifischen Bedingungen mit exogenen kurzkettigen Fettsäuren versorgt, tritt ein kontinuierlicher Konzentrationsanstieg bei verschiedenen fruchttypischen Aromakomponenten auf, der mehr als 36 Std andauert. Bei Erdbeermaceraten ist die Biosynthese der Methylester verschiedener geradkettiger Fettsäuren (C12–C18) die wichtigste gaschromatographisch nachweisbare Veränderung nach Zugabe der genannten Precursoren. Bei Bananenpulpe führt dieselbe Macerationsmethode zu Homogenaten, deren Estergehalte einige Std konstant bleiben. Ein Teil der Befunde spricht dafür, daß der enzymatischen Zerkleinerung der Fruchtgewebe eine wundinduzierte Reorganisation des Stoffwechsels folgt, wobei die prinzipielle Fähigkeit zur Carboxylesterbildung mehr als vier Tage erhalten bleibt.

Formation of 8,15-dihydroxy eicosatetraenoic acidvia 15- and 12-lipoxygenases in fish gill

Metabolites of arachidonic acid are important regulators of biological function in a variety of mammalian tissues. We have demonstrated similar lipoxygenase enzyme activities in fish gills and mammalian lungs suggesting that their metabolites may have matching functions. Fish gills were investigated for their ability to generate dioxygenated metabolites of polyunsaturated fatty acids. Fatty acids, including arachidonic acid, were incubated with crude tissue homogenates and polar metabolites were extracted, derivatized and analyzed by high performance liquid chromatography, gas chromatography and mass spectrometry. The major dihydroxy metabolite of arachidonic acid was characterized as 8(LR), 15(LS)-dihydroxyeicosatetraenoic acid. This product was formed by the sequential action of the 15- and 12-lipoxygenases in the tissue. The formation of the dihydroxyeicosatetraenoic acid by crude tissue homogenates was significantly enhanced by the addition of 1 mM reduced glutathione. The metabolism of other polyunsaturated fatty acids, including eicosapentaenoic acid and docosahexaenoic acid, to dihydroxy acids was consistent with their relative ability to serve as substrates for the initial 15-lipoxygenase reaction.

Catabolism of geraniol by cell suspension cultures of Citrus limon

The addition of geraniol to cell suspension cultures of Citrus limon resulted in the rapid formation of nerol, citronellol, geranic acid and citronellic acid. Concurrently, a transient accumulation of bound forms of branched chain fatty acids, and, with a few hours delay, of regular chain C2 to C12 fatty acids was elicited. A concerted action of combined alpha/beta-oxidation enzymes on the terpenic acids, followed by an enlarged acetyl CoA pool is suggested. Terpene catabolism in plants and in vitro plant cells is discussed.

Elicitation of volatile compounds in photomixotrophic cell culture of Petroselinum crispum

Photomixotrophic cells of Petroselinum crispum accumulated >500 mg chlorophyll per kg wet weight and grew well in a broad range of phytoeffector conditions. Autoclaved fungal cells were lethal for photoheterotrophic cells, but induced in photomixotrophic cells the formation of volatile n-alkanes, phthalides, coumarins, and elemicine. Most of the compounds elicited reached a concentration maximum between 20 and 30 h after addition of the mycelium, whereas the group of n-alkanes increased steadily during the 90 h monitored. Maximum concentrations were: 12 mg of graveolone, 1 mg of bergapten, 0.5 mg of sedanenolide, and 0.5 mg of n-tetradecane per 1 nutrient medium. A dose/effect relationship was found; 10 to 25 g of fungal wet weight per 1 culture medium resulted in maximum accumulation of volatiles. The formation of volatiles by photomixotrophic in vitro cells is discussed as an integral part of plant responses to ecological stress.

C6-aldehyde formation from linolenic acid in fruit cells cultured in vitro

Heterotrophic plant cells of three apple cultivars, two pear cultivars, strawberry, and tomato were cultured in vitro. Cell homogenates in the presence of linolenic acid formed n-hexanal, (Z)-3-hexenal, (E)-2-hexenal, and, in one apple cultivar, (Z)-3-hexenol and its acetate. Homogenates of photomixotropic apple cv. Goldparmäne cells contained eight times more (E)-2-hexenal than homogenates of non-green cells.

Variation of chlorophyll and essential oils in photomixotrophic cell cultures of Coleonema album (Thunb.)

Summary Callus cultures of Coleonema album were grown under different light regimes and in the presence of different concentrations of phytoeffectors and gelling agents. Both an increased photonic fluence and photoperiod stimulated the accumulation of chlorophyll (max 450 mg per kg wet weight) and of volatile monoterpenes. The application of different light sources showed that chlorophyll and terpene biosynthesis (max 130 mg per kg wet weight) were stably correlated during 11 subcultivations. Phytoeffector concentrations modulated some of the light effects: Formation of chlorophyll and aliphatic esters occurred in a broad range of phytoeffector conditions, while volatile terpenes were restricted to a narrow window. Increased concentrations of agar or gellan gum (≤ 12 g × L −1 decreased growth and increased concentrations of chlorophyll and volatiles. Photomixotrophic cells are discussed as an in vitro system to study the control of oligoisoprenoid formation in higher plants.

The peroxisomal dienoyl-CoA reductase pathway in pineapple fruit

Abstract Unsaturated acyl moieties were degraded by pineapple fruit tissue by the 2,4-dienoyl-CoA reductase pathway. 2 H-labelled sorbate was converted to 2 H-(3 E )-hexenoate and 2 H-butanoate by a peroxosomal fraction, but not by a mitochondrial one. The alternative pathway could represent a homeostatic reaction of the senescent tissue finally resulting in the genesis of volatile flavour components.

Isozymes in nutrient medium of suspension cultured apple cells (Malus sylvestris Mill.)

The time course of the activities of esterase, α-galactosidase, and β-glucosidase in cell sap and nutrient medium in in vitro cultured apple cells (Malus sylvestris Mill.) was studied. The corresponding isozyme patterns and the intracellular and extracellular isozyme patterns of acid phosphatase and polyphenol oxidase were compared using isozyme visualization methods adapted to ultra-thin-layer isoelectric focusing. Neither quantitative (total activity) nor qualitative (isozyme pattern) data were congruent for cell saps and nutrient media. Malate dehydrogenase, malic enzyme, and glutamate dehydrogenase occurred in cell sap only. The extracellular activities probably originate to a great part from a programmed release by intact cells. Nutrient media of plant cell cultures constitute a rich source of active plant isozymes.