Heterosides

Heterosides are built by glycosyltransferases (C 6). In most cases nucleoside diphosphates act as glycosyl donors. However, in some instances other energy- 

Cinnamic acid derivatives (o-coumarinic acid-j -D-glucoside, D 22.2.2) 

Formation of heterosides increases the water solubility of most aglycons and frequently is a prerequisite for accumulation or release of secondary products (El). 

Glycosylation and glycosidases. In The Biochemistry of Plants, Vol. 7, Secondary Plant Products (E. E. Conn, ed.), pp. 725-753. Academic Press, New York 1981 Loewus, F. A., Tanner, W. (eds.) Plant Carbohydrates I, Intracellular Carbohydrates (Encyclopedia of Plant Physiology, New Series, Vol. 13 A), Springer, Berlin-Heidelberg-New York 1982 

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Secoiridoids are complex phenols produced from the secondary metabolism of terpenes as precursors of several indole alkaloids (Soler-Rivas and others 2000). They are characterized by the presence of elenolic acid, in its glucosidic or aglyconic form, in their molecular structure. Oleuropein, the best-known secoiridoid, is a heterosidic ester of elenolic acid and 3,4- dihydroxyphenylethanol containing a molecule of glucose, the hydrolysis of which yields elenolic acid and hydroxytyrosol (Soler-Rivas and others 2000). 

Glucosidase, prepared from sweet or bitter almonds, acts both on ordinary /3-D-glucosides (heterosides) (I) and on disaccharides (holosides),... 

Enzymic hydrolysis (25-40°C) at the heterosidic bond of the chromogenic substrates was followed either continuously (via formation of 2 -chloro,4 -nitrophenol) at pH 5.5 (O.D. 405 nm) or discontinuously (4-methylumbel-liferone fluorescence at pH 10, emission at A > 435, excitation at A366 nm). Reaction rates were calculated from the linear increase of O.D. (em = 9000 M-1cm-1) or fluorescence (standardization with 4-methylumbelliferone) versus time. Alternatively, an HPLC method was used to follow the formation of chromophoric reaction products, phenols and glycosides (1). Concentrations were calculated from peak heights after appropriate standardization. 

A word of caution is appropriate, however. This was because unspecific cleavage at the heterosidic bond of these substrates was sometimes noticed, and the specificity was therefore not always exactly reflected. 

Cassia occidentalis L. C. torosa Cav. Wang Jiang Nan (Coffee senna, sicklepod) (seed, root) Anthraquinones, torosachrysone, n-methylmorpholine, apigenin, galactomannan, cassiollin, xanthorin, dianthronic heteroside, helminthosporin.4-33 496 Mild purgative, lower blood pressure, antioxidative, antiasthmatic, antitoxic, antimalarial, antibacterial, anthraquinones and hepatoprotective activities. 

Diace tyl-atractylodiol Diadzin-4,7-diglucoside Dially disulfide Diallyl sulfide Dianthrone glucoside Dianthronic heteroside Dianthus saponin Dibilone... 

Scutellarein heteroside Thymus amurensis, T. disjunctus, T. kitagawianus, T. komarovii, T. przewalskii, T. quinquecostatus... 

There are five anthocyanidins in the grape delphinidin 1, petunidin 2, malvidin 3, cyanidin 4, and peonidin 5. These aglycones exist in different heterosidic forms or as anthocyanins 3-monoglucosides, 3,5-diglucosides, and acylated heterosides, whose structures, in the case of malvidin, are represented by formulas 6, 7, and 8. In the acylated anthocyanins, one molecule of cinnamic acid, more generally p-coumaric acid, is esterified with the —OH group in the sixth position of a glucose molecule (12). 

Also, the phenolic compounds in olives have a strong influence on the flavor of the oil and seem to be responsible for the high oxidation resistance of olive oil. The phenolic content in the flesh of olive fruits ranges between 1% and 3%, w/w, (66) oleuropein, vanillic, caffeic, p-coumaric acid, rutin, luteolin-7-glucoside, heterosidic ester of caffeic acid, and hydroxytyrosol (verbascoside) have been identified in olive fruits. 

Applying periodic acid oxidation to reducing di- and oligo-saccharides having (1 — 4) linkages, J. E. Courtois observed the overoxidation phenomenon, which was further extended by study of the oxidation of malonic, malic, and citric acids. Two heteroside structures, amygdaloside and vician-oside, were also studied with this reagent. 

Franz G (1982) Glycosylation of heterosides (glycosides). In Loewus FA, Tanner W (eds) Encyclopedia of plant physiology New Series Volume 13A Carbohydrates I Intracellular Carbohydrates. Springer, Berlin Heidelberg New York, p 384... 

Scheidegger, J J. and Cherbuliez, E., Hederacoside A, a heteroside extracted from English ivy, Helv. Chim. Acta, 38, 547, 1955 Chem. Abs., 50, 1685g, 1956. 

Experiments should be performed using pH buffers going from 2 to 10. Add to a test tube 0.5 ml of 1 mM heteroside, 1 ml of buffer, and 2 ml of enzyme. Then, mix with the vortex and allow to incubate for 3 min. Finally, add 3 ml of Na2CC>3. 

In a test tube, mix 0.5 ml of 1 mM heteroside and 1 ml of pH 7 buffer. Then, keep the test tube for 5 min at the temperature of the experiment. Then, add 0.5 ml of the enzyme solution without removing the test tube from its position, mix the whole solution slowly, and allow the hydrolysis to continue for 5 min. Then, add 3 ml of Na2C03. A blank tube is prepared by adding Na2CC>3 before the enzyme. Read the OD at 405 nm at room temperature, and then plot it as a function of temperature. 

Plotting 1/v vs. [I] at the two heteroside concentrations yields the graphs of Figure 4.10. As we can see from the high values of 1/v, the reaction rate was expressed here in PNP concentration per minute. 

Darriet, P., Boidron, J. N. Dubourdieu, D. (1988). L hydrolyse des heterosides terpeniques du Muscat a petits grains par les enzymes periplasmatiques de Saccharomyces cerevisiae. Conn. Vigne Vin, 22, 89-195. 

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