Myricetin phenolic compounds

Finally, we tested the actions of other phenolic compounds derived from various sources including fruits, vegetables, and plants. Among those tested, piceatannol, a natural resveratrol analog, was the most potent, followed by morin and myricetin. In contrast, quercetin and kaempferol were ineffective. Moreover, phenolic acids— namely, tannic and gallic acids—were the only ones that were neuroprotective in our model, as summarized in Table 6.1. 

Honey contains an extensive diversity of phenolic compounds as secondary constituents, notably flavonoids and phenolic acids (Arraez-Roman et al., 2006 Baltrusaityte et al., 2007 Estevinho et al., 2008). The flavonoid content reaches about 6000 mg/kg, consisting mainly of flavanones and flavones (Anklam, 1998). The main flavonoids are myricetin, tricetin, quercetin, hesperidin, luteolin, kaempferol, pinocembrin, chrysin, pinobanksin,... 

In products with complex combinations of various types of flavonoids and other phenolic compounds, effort has been made to ascribe the antioxidant activity of the product to different classes of polyphenols. Frankel et al. (1995) studied 20 selected California wines and related the antioxidant activity to the polyphenolic components of the wines, rather than to resveratrol. Antioxidant activity was measured by the ability of the wines to inhibit copper-catalyzed oxidation of human LDL. The correlation coefficient between antioxidant activity and total phenolic components of the wines was r = 0.94. Individual phenolic compounds (gallic acid, catechin, myricetin, quercetin, caffeic acid, rutin, epicatechin, cyanidin, malvidin-3-glucoside) contributed to the antioxidant activity. The correlation coefficient for the compounds ranged from r = 0.92 to r = 0.38 in descending order. 

It is well known that in reversed phase the retention time of phenolic compounds is higher for substances that are less polar (myricetin, quercetin, kaempferol), while polar molecules as gallic acid, protocatechuic acid, epigallocatechin are eluted faster [43], Alternative high-strength silica (HSS) T3 columns have also been investigated. 

Figure 7.10 Separation of a standard mixture of 13 phenolic compounds by automated multiple development by use of a 20-step universal gradient composed of acetonitrile, methylene chloride, and hexane. The drying time was 4 min, and the gas phase for conditioning the plate between runs was prepared from 10% aqueous formic acid. The phenols were (1) rutin, (2) kaempf-erol-3-rutinoside, (3) quercetin-3-arabinoside, (4) quercetin-3-galactoside, (5) chlorogenic acid, (6) myricetin, (7) caffeic acid, (8) quercetin, (9) apigenin, (10) ferulic acid, (11) acacetin, (12) flavon, (13) coumarin. [Reprinted from Lodi et al. (1991) with permission of Alfred Huethig Verlag GmbH.]...

Phenolic substances in red wine were shown to inhibit LDL oxidation in vitro [95]. In previous studies, red wine-derived phenolic acids [115,116], resveratrol [117], flavonols (quercetin, myricetin) [68,118,119], catechins [66,120], and the grape extract itself [121,122] have been shown to possess antioxidant properties. The finding that ethanol and wine stripped of phenols did not affect LDL oxidation further confirmed that the active antioxidant components in red wine are phenolic compounds [123]. Red wine fractionation revealed major antioxidative potency to monomeric catechins, procyanidins, monomeric anthocyanidins, and phenolic acids [123]. The flavonol quercetin and the flavonol catechin were both tested for antioxidative and antiatherogenic effects in the atherosclerotic E° mice [111]. E° mice at the age of 4 weeks were supplemented for up to 6 weeks in their drinking water with placebo (1.1% alcohol) or with catechin or quercetin (50 pg/day/mouse). The atherosclerotic lesion area was smaller by 39% or by 46%, respectively, in the treated mice than in E° mice that were treated with placebo (Fig. 4A-E). 

A great number of phenolic compounds, including yellow flavonoids, anthocyanins, the ellagic, gallic and p-coumaric acids, as well as quercetin, myricetin, and kaempferol derivatives have been identified in the cashew apple (Michodjehoun-Mestres etal. 2009 Hoffinann-Ribani et al. 2009 Brito et al. 2007 Moura et al. 2001), while condensed tannins and anacardic and ascorbic acids have been identified in cashew juice and cajuina. It is also known that cashew apple skins are 15-20 times richer in total phenolic compounds than their flesh (Michodjehoun-Mestres et al. 2009). In addition, lutein, zeinoxanthin, cis- and tra s -P-cryptoxanthin, a-carotene and p-carotene cis and trans) were identified as the major carotenoids present in three different varieties of ripe cashew apple (elongated yellow, elongated red, and rounded red) (Assunfao a/. 2003). 

Rice and Pancholy studied the effects on nitrification of seven phenolic compounds (caffeic acid, chlorogenic acid, ferulic acid, isochlorogenic acid, isoquercitrin, myricetin and quercetin). They found with soil suspensions that Nitro somonas was much more susceptible to inhibition than Nitrobacter, and reported that the nitrification of ammonium by Nitro somonas was completely inhibited by ferulic acid at the extremely low concentration of 10 nil. Kov ever, since their procedure was based on a colorimetric test for the presence of nitrite, the possibility appears to exist that the result may have been due to the loss of nitrite rather than to inhibition of its formation. The other phenolic compounds tested v ere reported to cause inhibition of nitrification by Nitrosomonas at concentrations greater than 1 pM. 

Myricetin is a phenolic compound isolated from the aerial part of Abel-... 

Effects of Allelochemlcals on ATPases. Several flavonoid compounds inhibit ATPase activity that is associated with mineral absorption. Phloretin and quercetin (100 pM) inhibited the plasma membrane ATPase Isolated from oat roots (33). The naphthoquinone juglone was inhibitory also. However, neither ferulic acid nor salicylic acid inhibited the ATPase. Additional research has shown that even at 10 mM salicylic acid inhibits ATPase activity only 10-15% (49). This lack of activity by salicylic acid was substantiated with the plasma membrane ATPase Isolated from Neurospora crassa (50) however, the flavonols fisetln, morin, myricetin, quercetin, and rutin were inhibitory to the Neurospora ATPase. Flavonoids inhibited the transport ATPases of several animal systems also (51-53). Thus, it appears that flavonoids but not phenolic acids might affect mineral transport by inhibiting ATPase enzymes. 

Flavonoids are not always essential signal molecules in mycorrhizal symbioses, however various other phenolic acids can elicit similar effects. " Compounds that actively promote the growth of AMF (i.e., kaempferol, quercetin, and myricetin) " are also required for pollen germination and growth of the germ tube. " " Thus, these compounds may have some general effect on cell elongation.It has been concluded that flavonoids stimulate, but are not essential for mycorrhiza formation. 

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