Phloridzin

It is known that the naturally occurring dihydrochalcone glycosides phloridzin (75) and glycyphillin (76), which are 2-yl glycosides, possess little or no sweetness, whereas phyllodulcin (77), which is not a glycoside, has the same taste properties as the dihydrochalcones it is 400 times sweeter than sucrose. ... 

French researchers provided an alternative to the tartrazine synthetic colorant (E 102), valorizing a phloridzine oxidation product (POP) generated as a by-product of the cider industry. Phloridzine is a polyphenol specific to apples and shows good antioxidant capacity. When apples are pressed to yield juice, phloridzine, oxygen, and polyphenoloxidase enzyme combine to form POP. This brilliant yellow natural colorant with nuances dependent on pH level can be incorporated easily into water-based foods such as beverages (juices, syrups) and confectionery creams because it is stable during production processes. Details about the specific formulations of these colorants are presented in Section 5.1. 

Chalcones and dihydrochalcones have been reported in a restricted number of foods (Robards and others 1999 Tomas-Barbcran and Clifford 2000). Chalconaringenin occurs in tomato skin, but the acid extraction conditions of the usual polyphenol analyses convert the chalcone to the corresponding flavanone (naringenin) in the tomato. The most common dihydrochalcones found in foods are phloretin glucoside (phloridzin) and phloretin xylogalactoside, which are characteristic of apples (see Table 2.2) and derived products such as apple juice, cider, and pomace (Robards and others 1999 Tomas-Barbcran and Clifford 2000). 

Fig. 2.56. HPLC chromatogram of (a) Golden peel and (b) Golden pulp extracts at 280 nm. Peaks 1 = procyanidin B3 2 = procyanidin Bl 3 = ( + )-catechin 4 = procyanin B2 5 = chlorogenic acid 6 = ( — )-epicatechin 7 = caffeic acid 8 = phloretin derivative 9 = phloridzin 10 = rutin 11, 12 and 13 = flavonol glucosides. Reprinted with permission from A. Escarpa et al. [160].

RP-HPLC methods have been frequently applied for the investigation of various chemical, biochemical and biophysical processes in in vitro model systems. Thus, the separation of new compounds achieved by enzymatic oxidation of phloridzin was carried out by semi-preparative RP-HPLC. Phloridzin was incubated with a polyphenol oxidase prepared from apple pulp for 6h at 30°C under air agitation. After incubation the suspension was filtered, stabilized by NaF and injected into the RP-HPLC column using diluted acetic acid-ACN gradient. The new compounds were isolated and identified by NMR and MA techniques. The proposed mechanism of the formation of new phloridzin derivatives 3 and 4 is shown in Fig. 2.159. The results illustrate that RP-HPLC can be successfully used for the study of enzymatic processes in model systems [331],... 

C. Le Guerneve, P. Sanoner, J.-F. Drilleau and S. Guyot, New compounds obtained by enzymatic oxidation of phloridzin. Tetrahedron Lett. 45 (2004) 6673-6677. 

Specific activation or inhibition Transport of glucose can be increased or decreased by specihc compounds insulin increases the transport whereas phloridzin, a plant glycoside, inhibits glucose transport by muscle. Insulin increases glucokinase activity in liver, whereas a plant sugar, mannoheptulose, inhibits glucokinase activity. Hexokinase is inhibited by its product, glucose 6-phosphate. 

The human data available are still comparatively limited. Most human studies show a considerable interindividual variation. Occasionally, a much greater variation is suggested, as, for example, the detection of phloridzin in the plasma of only one out of six volunteers, and the detection of curcumin sulfate in the feces of only one volunteer out of 15. The limited nature of the data available make it difficult to generalize with regard to either efficacy or safety. 

Blum, A.L., Haemerli, U.P., and Lorenz-Meyer, H., Is phloridzin or its aglycon the inhibitor of intestinal glucose transport A study in normal and lactase-deficient men, Eur. J. Clin. Invest., 5, 285, 1975. 

Phloridzin, a toxic glycoside from the bark of the pear tree, blocks the normal reabsorption of glucose from the kidney tubule, thus causing blood glucose to be almost completely excreted in the urine. In an experiment, rats fed phloridzin... 

The phenolics ( + )catechin and (— )epicatechin are common flavanols in several fruits (128). Apples and pears contain other phenolic compounds such as quinic, shikimic, chlorogenic, and caffeic acids (39). Durkee and Poapst (162) reported that the two major phenolic constituents of core tissues and seeds of McIntosh apples were chlorogenic acid and phloridzin. After hydrolysis of extracts from core tissues, the identified phenolics were phloretin, caffeic acid, p-coumaric acid, phloretic acid, and trace amounts of ferulic acid. Studies have shown that apple leucoanthocyanins yield catechin, epicatechin, cyanidin, and pelargonidin after hydrolysis (163, 164). Van Buren et al. (164) also reported that a purified leucoanthocyanin from apples was either a dimer or oligomer containing ( —) epicatechin, and 5,7,3, 4 -flavin-3,4-diol. 

The embryonic and newborn animals, however, do not spill glucose into the urine, and bladder samples taken following glucose injection indicate that the sugar is completely reabsorbed. Segal et al (85) report that a rudimentary transport system is present in the newborn, as indicated by a decrease in accumulation in the presence of phloridzin. Thus, it seems possible that some more primitive mechanism for glucose reabsorption may operate in the embryonic kidney. 

Diedrich has also measured by indirect means the content of the phloridzin-sensitive transport site in dog kidney and obtained a figure of 0.68 fimole per 100 grams of tissue (113). Dog kidney mutarotase has not yet been purified, but the content in those species where the turnover number is known (58) is calculated to be about 0.5 /xmole per 100 grams of cortex, in fair agreement with Diedrich s estimate for the transport site. 

It was also found as a result of this work that mutarotase appears to have two binding sites for phloridzin, one for the aglycone portion and one for the sugar. The lesser inhibition by phloridzin is thought to reflect reversal of the inhibition produced by the aglycone portion of the... 

Phloridzin, quercetin-3-gaiactoside glucoside, quercetin-3-rhamnoside... 

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