Procyanidins concentrations

Another membrane property physically affected by flavonoids is the surface potential. Working with liposomes composed of PC and PS, we found that (—)-epicatechin and certain procyanidins (dimer to hexamer) decreased liposome surface potential. This effect relied on both, procyanidin concentration and number of monomeric units [Verstraeten et al., 2003]. On the other hand, when liposomes were composed exclusively of PC, it was found that (—)-epi-catechin dimers Al and B2, and the trimers A and C2 increased liposome surface potential in a concentration-dependent manner [Verstraeten et al.,... 

Different cocoa procyanidin extracts obtained from cocoa beans, cocoa nibs, cocoa liqnor, and cocoa powder were analyzed, and their concentrations of procyanidins ranged from 6 to 30 mg/g of lyophilized extract [28,29]. These cocoa sources corresponded to the Forastero variety from Ghana (West Africa). The cocoa extract from the nibs was the most abundant in procyanidins, followed by the extracts from bean and cocoa liquor, and the lower procyanidin concentration was observed in the extract from cocoa power [28]. 

The concentrations of the procyanidin metabolites generated in the plasma samples were in hundreds of nM after an acute intake of 0.5 mg/g hazelnut skin extract [40], ranged from 85 pM to low pM after an acute intake of 1 and 5 g/kg [31,33], or a long-term intake of 50 mg/kg [37] of a grape seed phenolic extract. Higher procyanidin concentrations were found when 5 g/kg of hazelnut skin extract was ingested, and these were from hundreds to thousands of pM [36]. These results are shown in Table 14.3. 

Proanthocyanidins (PAs), also known as condensed tannins, are oligomeric and polymeric flavan-3-ols. Procyanidins are the main PAs in foods however, prodelphinidins and propelargonidins have also been identified (Gu and others 2004). The main food sources of total PAs are cinnamon, 8084 mg/100 g FW, and sorghum, 3937 mg/100 g FW. Other important sources of PAs are beans, red wine, nuts, and chocolate, their content ranging between 180 and 300 mg/100 g FW. In fruits, berries and plums are the major sources, with 213.6 and 199.9 mg/100 g FW, respectively. Apples and grapes are intermediate sources of PAs (60 to 90 mg/100 g FW), and the content of PAs in other fruits is less than 40 mg/100 g FW. In the majority of vegetables PAs are not detected, but they can be found in small concentrations in Indian squash (14.8 mg/ 100 g FW) (Gu and others, 2004 US Department of Agriculture, 2004). 

Complete removal of procyanidin is not necessary to overcome anti-nutritional effects. Removal of most procyanidin or addition of sufficient protein will overcome anti-nutritional effects of procyanidins. Small concentrations of procyanidin can be easily overcome by adding protein. 

PROCYANIDINS ANALYTICAL CHARACTERISTICS AND CONCENTRATION IN SIX FRENCH WHITE WINES... 

A 12-fold increase in plasma epicatechin concentration from 22 to 257 nmol/L was reported by Rein et al [105] after consumption of 80 g semisweet (procyanidin rich) chocolate within 2 h after ingestion. The total antioxidant capacity of plasma increases of 31% within the same time, and plasma 2-thiobarbituric acid reactive substances decreased up to 40%. These data support that consumption of chocolate increases plasma epicatechin concentrations and decreases plasma baseline oxidation products. These results have been confirmed in another study by Wang et al [106]. 

Fractionate phenolic acids and flavonoids using Sephadex LH-20 column. For phenolic acids and flavonol glycosides, filter the fruit juice through 0.45-/nm (type HA) filter. For procyanidins apply juice onto the Sephadex LH-20 column, wash with 20% MeOH (30 ml), then elute with MeOH (15 ml), concentrate to dryness, redissolve in 2 ml H20, and filter through 0.45-/nm (type HA) filter. 

Figure 16.5 Influence of carbohydrate concentration on the formation of aggregates between BSA (6.1 x l(T3mM) and oligomeric procyanidins from grape seed (O.lOmM) (in 12% aqueous ethanol, 0.1 M acetate buffer, pH5.0). [78],...

Table 16.1 Aggregation inhibitor factor (FA ) of the interaction between BSA (5 x 10-3 mM) and procyanidins of different molecular weights (in 12% aqueous ethanol, 0.1 M acetate buffer, pH 5.0), at the concentrations indicated under [Fraction], chosen to obtain similar NTU values (around 12 NTU) [81].

Some recent evidences have shown that a basic PRP binds condensed tannins much more effectively than a-amylase. In Figure 16.10, it can be seen that the light-scattering intensity caused by aggregation increases with the concentration of procyanidins until a maximum after which the light scattered intensity remains constant even with a further increase in tannin concentration. 

Figure 16.10 Influence of the concentration of procyanidins (gallate tetramers and pentamers) on the aggregation with two salivary proteins (a) a-amylase (0.4pM) and (b) IB8c (0.5p/W) in 12% aqueous ethanol, 3.1 mM acetate buffer, pH 5.0 [104],...

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