Rhamnose rates

The separation was carried out on a TSKgel Amide-80 column 4.6 mm i.d. and 25 cm long with a mobile phase consisting of a 80% acetonitrile 20% water mixture. The flow rate was 1 ml/min and the column was operated at an elevated temperature of 80°C. The saccharides shown were 1/ rhamnose, 2/ fucose, 3/ xylose, 4/ fructose, 5/ mannose, 6/ glucose, 7/ sucrose and 8/ maltose. The analysis was completed in less than 20 minutes. These types of separations including other biomonomers, dimers and polymers are frequently carried out employing refractive index detection. 

The data in Table VIII are presented in the order of the conformational stability observed for methyl glycosidation (see Table I on p. 99 and Table II on p. 105). In each of the three cases where data for both anomers are available, the trans-1,2 anomer is the more stable, and a lower rate-constant is observed. This is the same pattern as that observed in Table II. However the order of conformational stability given earlier is not observed here. The arabinofuranosides show the maximum stability, and the D-galactofuranosides and L-fucofuranosides, having similar conformations, show a similar stability, However, the furanosides of D-lyxose, n-mannose, and i>rhamnose show an unexpectedly high stability which is almost as great as those of the furanosides of the first-mentioned sugars. These data lead to the conclusion that the conformational stability for transition complexes... 

Fig. 4.—Rates of Consumption13 of Lead Tetraacetate by Some Aldoses (1) D-Mannose, (2) i.-Rhamnose, (3) D-Altrose, (4) D-Allose, (5) D-Galactose, and (6) D-Glucose (Temp. 0°).

Rooney et al (45) reported that the rate of carbonyl formation varied with the molecular structure of sugar. Xylose was most reactive as it produced the greatest quantity of carbonyls, followed by glucose, then maltose. In the presence of these sugars isoleucine was more reactive than phenylalanine. In a study on the Strecker degradation of valine-carbonyl, diacetyl showed the greatest reactivity followed by sorbose> arabinose>xylose>fructose>glucose>sucrose>rhamnose, Self(46). 

Figure 9. DCI mass spectrum of jujubogenin-glucose-rhamnose. Conditions ammonia ionizing gas at 0.25 torr filament heating rate 50 deg./sec 0.3 sec/scan. Inset figure reconstructed ion chromatogram of jujubogenin-glucose-rhamnose. Reproduced with permission from Ref. 29. Copyright 1981, Academic Press, Inc.

Fig. 3-25. Gradient elution of different sugar alcohols and saccharides. - Separator column Ion Pac AS6A eluent (A) water, (B) 0.05 mol/L NaOH + 0.0015 mol/L acetic acid gradient 7% B isocratically for 15 min, then to 100% B in 10 min flow rate 0.8 mL/min detection pulsed ampero-metry on a Au working electrode (post-column addition of NaOH) injection volume 50 pL solute concentrations 15 ppm inositol (1), 40 ppm sorbitol (2), 25 ppm fucose (3), deoxyribose (4), 20 ppm deoxyglucose (5), 25 ppm arabinose (6), rhamnose (7), galactose (8), glucose (9), xylose (10), mannose (11), fructose (12), melibiose (13), isomaltose (14), gentiobiose (15), cellobiose (16), 50 ppm turanose (17), and maltose (18).

Fig. 3-105. Separation of various sugar alcohols and saccharides. - Separator column CarboPac PA-1 eluent 0.15 mol/L NaOH flow rate 1 mL/min detection pulsed amperometry at a Au working electrode injection volume 50 pL solute concentrations 10 ppm xylitol, 5 ppm sorbitol, 20 ppm each of rhamnose, arabinose, glucose, fructose, and lactose, 100 ppm sucrose and raffmose, 50 ppm maltose.

Hawthorn extracts purportedly dilate coronary blood vessels, decrease blood pressure, increase myocardial contractility, and lower serum cholesterol (Anonymous, 1999). Benefits have been demonstrated in heart failure patients (Iwamoto et al., 1981). In patients with Stage II New York Heart Association (NYHA) heart failure, doses of 160-900 mg/d of the aqueous-alcoholic extract for up to 56 d showed an increase in exercise tolerance, decrease in rate/pressure product, and increased ejection fraction (Blumenthal, 1998). The active principles are thought to be flavonoids, including hyperoside, vitexin, vitexin-rhamnose, rutin, and oligomeric procyanidins (dehydrocatechins catechins and/or epicatechins) (Tyler, 1993 Blumenthal, 1997 Blumenthal, 1998 Bigus, 1998). 

Monosaccharides. M. are linear polyhydroxyalde-hydes (aldoses) or polyhydroxyketones (ketoses). Most important among M. are the pentoses (CjHiqO,) and hexoses (C6H,20 ). Important aldopentoses include, e.g., D- ribose, D- xylose, and L- arabinose. Important aldohexoses include D- glucose, D- man-nose, and D- galactose the major ketohexoses are D- fructose and sorbose. The 6- deoxy sugars L- fu-cose and L- L-rhamnose are also widely distributed hexoses. M. with more carbon atoms (heptoses 7 carbon atoms, octoses, etc.) or less carbon atoms (trioses 3 carbon atoms) do not occur in the free form in organisms but do play a role in carbohydrate metabolism as phosphate esters tetroses (4 carbon atoms) erythrose, threose are relatively rate. 

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