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Acetaldehyde and an apple a day
Explores the acetaldehyde scavenging potential of apple polyphenols
Date: 10/26/2012 3:32:50 PM ( 12 y ) ... viewed 24138 times Starting from acetaldehyde, we found that we could work forward to connect to a folklore (but not recommended) treatment for illness that has been used throughout history:
• See "Acetaldehyde + Urophagia" http://curezone.com/blogs/fm.asp?i=1998795
Can we start with a (highly recommended) folklore treatment and work our way back to acetaldehyde?
Why single out an apple from all of the other fruits and vegetables in our dietary rainbow?
Phloridzin and phloretin are flavonoids, a class of polyphenolic compounds that used to be referred to as vitamin P, occurring in many plants that form part of the human diet. Phloridzin and phloretin occur primarily in apples [1] with varying concentration depending on many factors such as the condition of cultivation, harvest and storage/processing of the apples [2].
Since these compounds have been shown to have the ability to scavenge reactive dicarbonyl species [3], a closer look at the polyphenolic ring of phloretin is warranted in relation to acetaldehyde.
Deprotonation and protonation of acetaldehyde can result in reactive ionic species. The deprotonation of acetaldehyde forming the enolate anion with a negative carbon atom has already been described in regards to the formation of crotonaldehyde from the condensation of two acetaldehyde molecules:
• See "Acetaldehyde + Enolate Ion" http://curezone.com/forums/fm.asp?i=1989003
If the electronegative oxygen atom of acetaldehyde captures a proton, then a carbocation containing a positive carbon atom can be formed:
The ability of acetaldehyde to form either an anion (-) or a cation (+) depending upon the pH of the surrounding milieu demonstrates why it is so highly reactive with other molecular configurations. This is both bad news and good news…
The bad news is that acetaldehyde can be rapidly damaging to essential body structures and enzymes with a wide diversity of disease processes the result. The good news is that many different kinds of molecular configurations can serve as acetaldehyde scavengers to prevent this kind of damage providing that the right substances are ingested so as to be available where and when the yeast is releasing this toxin. Given the connection between yeast-released acetaldehyde and disease processes, this explains why there are so many different "cure-alls" that appear to have beneficial effects for so many different conditions. Recognizing their common mode of action is an important step in giving individuals healing choices that maximize the benefits and minimize the risk. Although the ultimate goal is to reduce the actual production of acetaldehyde by the elimination of viable budding yeast cells, the stranglehold exerted by yeast-released acetaldehyde must first be broken so that other techniques aimed at yeast abatement may succeed.
The electrophilic carbocation is ideal for ethylidene bridge cross-linking condensation (water-releasing) reactions of nucleophilic configurations. Ethylidene bridge formation has been seen before in this series in the reaction between acetaldehyde and urea:
• See "Acetaldehyde + Urea" http://curezone.com/blogs/fm.asp?i=1998795
Phloroglucinol exists in an equilibrium state between its two tautomers:
where migration of a proton is accompanied by the switch of a double bond to a single one.
We have already seen that acetaldehyde finds quinones attractive for binding:
• See "Acetaldehyde + Quinones" http://curezone.com/blogs/fm.asp?i=1990595
The addition of a third hydroxyl/ketone electron-donating group in the meta configuration of phloroglucinol can generate electron-rich nucleophilic centers at the unsubstituted carbon sites [4]. This means that molecular structures containing polyphenolic rings similar to phloroglucinol are prime candidates for cross-linking reactions via the carbocation intermediate form of acetaldehyde:
Ethylidene-linked products usually undergo polycondensation; the initial products evolve with a high degree of polymerization that finally precipitate and give rise to dimers, trimers, and tetramers of polyphenols in different structural forms [5].
The rapid browning of some types of apples when cut is indicative of the oxidation and cross-linking of polyphenols and their corresponding o-quinones. By eating an apple a day snack, this propensity for rapid reaction is expressed in the proximity of the electrophilic nature of acetaldehyde and the effect is like a sponge mopping up the yeast-released toxin. The delivery mechanism for the acetaldehyde scavenger is as important a factor as the chemical structure of the reactive component(s). The fibrous nature of the apple meat provides a contact matrix with yeast cell membranes that will be persistently situated for a sufficient duration to engage acetaldehyde as it is emitted from the yeast cells. This is also an attribute of the viscous nature of sulfurated flax oil (Wondro) [6] where disulfide bonds rather than polyphenols/quinones provide the acetaldehyde binding loci. The substances are structurally and chemically distinct but similar beneficial effects result from the sequestration of acetaldehyde.
Ethanol, acetaldehyde, and acetic acid are so closely related in structure via oxidation/reduction reactions that the wine industry is quite familiar with the occurrence of all three of these substances in varying amounts in their products.
The acetaldehye cross-linking of polyphenols that occur in wine has been well-studied and documented [7]. Since the polyphenols that occur in wine and other foods are far more complex than the illustration of cross-linking shown above for phloroglucinol, the resulting structures are also more involved. For example, consider the structure of tannic acid found in tea and wine:
Regardless of the molecular complexity, once acetaldehyde has formed an ethylidene bridge in these polyphenols, it has lost its aldehyde reactivity and its potential for inappropriate disease-causing reactions with other molecules in the body has been neutralized.
If acetaldehyde emanating from yeast metabolism isn't scavenged, then the consequences can be dire indeed. DNA adducts or interstrand cross-links formed from reactive carbonyl species such as acetaldehyde, malondialdehyde, and crotonaldehyde can prohibit the transitory separation of complementary DNA strands and interfere with the replication and transcription processes of DNA, something that is fundamentally and critically essential to the health and well-being of each and every cell in the body.
In a study which tested several bioactive phenolic compounds for their potential to prevent interstrand cross-links in calf thymus DNA, it was found that phloretin (but not phloridzin) was effective in preventing DNA cross-links by quenching acetaldehyde providing that it reacted with the acetaldehyde before it had a chance to form an adduct with DNA [8]. Orally consumed phloridzin is nearly entirely converted into phloretin by hydrolytic enzymes in the small intestine [9].
This may provide a clue as to why apples stand out above other polyphenol-containing foods which have some beneficial effects but where the rings contain only two hydroxyl groups rather than three.
The same study also observed that epigallocatechin gallate (found in green tea) could prevent DNA cross-links even after the formation of acetaldehyde adducts with DNA strands. Note that both epigallocatechin gallate and phloretin have benzenetriol rings while quercetin and resveratrol have at most benzenediol rings.
In relation to wine-fault (spoilage) the taste of acetaldehyde is described as green apple-like, grassy, sour and metallic. The association with green apples is indicative of the fact that this fruit actually contains small amounts of acetaldehyde [10].
It is interesting that an aromatherapy technique for dealing with headaches is to cut a green apple in half and sniff it. The implications here are that acetaldehyde (emanating from yeast) may have something to do with the headache symptoms and that exposure to a vaporous dilution of this substance relieves the acetaldehyde aggravation of brain biochemistry. This is similar to the postulated motivational influence for alcohol cravings that increase the concentration of acetaldehyde in the liver:
• See "Acetaldehydism" http://curezone.com/forums/fm.asp?i=1985494
where the energetic (homeopathic) signal of acetaldehyde may result in a down-regulation of acetaldehyde production by Candida albicans throughout the body.
[1] Escarpa A et al., "High-performance liquid chromatography with diode-array detection for the determination of phenolic compounds in peel and pulp from different apple varieties.", J Chromatogr A. 1998 Oct 9;823(1-2):331-7.
http://www.ncbi.nlm.nih.gov/pubmed/9818410
[2] Spanos GA et al., "Influence of processing and storage on the phenolic composition of apple juice", J. Agric. Food Chem., 1990, 38 (7), pp 1572–1579
http://pubs.acs.org/doi/abs/10.1021/jf00097a031
[3] Shao X et al., "Apple polyphenols, phloretin and phloridzin: new trapping agents of reactive dicarbonyl species.", Chem Res Toxicol. 2008 Oct;21(10):2042-50.
http://www.ncbi.nlm.nih.gov/pubmed/18774823
[4] Zhu Q et al., "Natural Polyphenols as Direct Trapping Agents of Lipid Peroxidation-Derived Acrolein and 4-Hydroxy-trans-2-nonenal", Chem. Res. Toxicol., 2009, 22 (10), pp 1721–1727.
http://www.ncbi.nlm.nih.gov/pubmed/19743801
[5] Es-Safi NE et al., "Studies on the acetaldehyde-induced condensation of (-)-epicatechin and malvidin 3-O-glucoside in a model solution system.", J Agric Food Chem. 1999 May;47(5):2096-102.
http://www.ncbi.nlm.nih.gov/pubmed/10552502
[6] "Wondro -- Inside Out", 2012
http://www.scribd.com/doc/101099776
http://www.epubbud.com/book.php?g=7D42SJH6
[7] Saucier C et al., "First Evidence of Acetaldehyde-Flavanol Condensation Products in Red Wine", Am. J. Enol. Vitic 1997 vol. 48 no. 3 370-373
http://www.ajevonline.org/content/48/3/370.abstract
[8] To Tsz-kin James, "Protective effects of some bioactive phenolic compounds against DNA adduct formation and interstrand cross-links caused by reactive carbonyl species in chemical models.", University of Hong Kong, 2011.
http://dx.doi.org/10.5353/th_b4608455
[9] Crespy V et al., "Bioavailability of phloretin and phloridzin in rats.", J Nutr. 2001 Dec;131(12):3227-30.
http://www.ncbi.nlm.nih.gov/pubmed/11739871
[10] Power FB et al., "The Odorous Constituents Of Apples. Emanation Of Acetaldehyde From The Ripe Fruit.", J. Am. Chem. Soc., 1920, 42 (7), pp 1509–1526
http://pubs.acs.org/doi/abs/10.1021/ja01452a029
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