Mechanisms of Budwig diet
我发现了来自世界各地被诊断为晚期癌症(所有类型的癌症)的人们的推荐信，他们被送回家等死，现在过着健康、正常的生活。不仅Budwig博士一直在欧洲使用她的协议为治疗癌症,但她也对其他慢性疾病,如关节炎、心脏梗塞, 心律不齐,牛皮癣,湿疹(其他皮肤疾病),免疫缺陷综合症(多发性硬化和其他自身免疫性疾病),糖尿病,肺(呼吸道条件)、胃溃疡、肝癌、前列腺癌、中风,脑部肿瘤,脑(加强活动), 动脉硬化等慢性疾病。在传统医学失败的地方，Budwig博士的方案被证明是成功的。
由于Budwig博士提到了增强大脑功能，我相信不仅多发性硬化症，ALS“Lou Gehrig’s Disease”、帕金森症和阿尔茨海默氏症也会对她的方案产生重大影响。我还相信，该方案在疾病早期可能产生最大的影响，并且很可能完全逆转这些疾病。Budwig博士说:“一个瑞典人已经证明(没有大脑功能)完全可以在没有OMEGA-3不饱和脂肪的情况下发生。毫无疑问，大脑的每一项功能——从科学的角度来看——都需要OMEGA-3不饱和脂肪的简单激活作用。
Mechanisms of Budwig diet
Dr. Budwig was born in Germany in 1908. She passed away in 2003 at the age of 95. She has been referred to as a top European cancer research scientist, biochemist, blood specialist, German pharmacologist, and physicist. Dr. Budwig was a seven-time Nobel Prize nominee.
In Germany in 1952, she was the central government’s senior expert for fats and pharmaceutical drugs. She’s considered one of the world's leading authorities on fats and oils. Her research has shown the tremendous effects that commercially processed fats and oils have in destroying cell membranes and lowering the voltage in the cells of our bodies, which then result in chronic and terminal disease. What we have forgotten is that we are body electric.
he cells of our body fire electrically. They have a nucleus in the center of the cell which is positively charged, and the cell membrane, which is the outer lining of the cell, is negatively charged. We are all aware of how fats clog up our veins and arteries and are the leading cause of heart attacks, but we never looked beyond the end of our noses to see how these very dangerous fats and oils are affecting the overall health of our minds and bodies at the cellular level.
Dr. Budwig discovered that when unsaturated fats have been chemically treated, their unsaturated qualities are destroyed and the field of electrons removed. This commercial processing of fats destroys the field of electrons that the cell membranes (60-75 trillion cells) in our bodies must have to fire properly (i.e. function properly).
The fats' ability to associate with protein and thereby to achieve water solubility in the fluids of the living body is destroyed. As Dr. Budwig put it, “the battery is dead because the electrons in these fats and oils recharge it.” When the electrons are destroyed the fats are no longer active and cannot flow into the capillaries and through the fine capillary networks. This is when circulation problems arise.
Without the proper metabolism of fats in our bodies, every vital function and every organ is affected. This includes the generation of new life and new cells. Our bodies produce over 500 million new cells daily. Dr. Budwig points out that in growing new cells, there is a polarity between the electrically positive nucleus and the electrically negative cell membrane with its high unsaturated fatty acids. During cell division, the cell, and new daughter cell must contain enough electron-rich fatty acids in the cell's surface area to divide off completely from the old cell. When this process is interrupted the body begins to die. In essence, these commercially processed fats and oils are shutting down the electrical field of the cells allowing chronic and terminal diseases to take hold of our bodies.
A very good example would be tumors. Dr. Budwig noted that “The formation of tumors usually happens as follows. In those body areas which normally host many growth processes, such as in the skin and membranes, the glandular organs, for example, the liver and pancreas or the glands in the stomach and intestinal tract—it is here that the growth processes are brought to a stand still. Because the polarity is missing, due to the lack of electron rich highly unsaturated fat, the course of growth is disturbed—the surface-active fats are not present; the substance becomes inactive before the maturing and shedding process of the cells ever takes place, which results in the formation of tumors.”
She pointed out that this can be reversed by providing the simple foods, cottage cheese, and flax seed oil, which revises the stagnated growth processes. This naturally causes the tumor or tumors present to dissolve and the whole range of symptoms which indicate a “dead battery are cured.” Dr. Budwig did not believe in the use of growth-inhibiting treatments such as chemotherapy or radiation. She was quoted as saying “I flat declare that the usual hospital treatments today, in a case of tumorous growth, most certainly leads to worsening of the disease or a speedier death, and in healthy people, quickly causes cancer.”
Dr. Budwig discovered that when she combined flaxseed oil, with its powerful healing nature of essential electron rich unsaturated fats, and cottage cheese, which is rich in sulfur protein, the chemical reaction produced makes the oil water soluble and easily absorbed into the cell membrane.
I found testimonials of people from around the world who had been diagnosed with terminal cancer (all types of cancer), sent home to die and were now living healthy, normal lives. Not only had Dr. Budwig been using her protocol for treating cancer in Europe, but she also treated other chronic diseases such as arthritis, heart infarction, irregular heart beat, psoriasis, eczema (other skin diseases), immune deficiency syndromes (Multiple Sclerosis and other autoimmune diseases), diabetes, lungs (respiratory conditions), stomach ulcers, liver, prostate, strokes, brain tumors, brain (strengthens activity), arteriosclerosis and other chronic diseases. Dr. Budwig’s protocol proved successful where orthodox traditional medicine was failing.
Since Dr. Budwig mentioned the strengthening of the brain, I believe not only Multiple Sclerosis, but also ALS “Lou Gehrig’s Disease”, Parkinson’s disease, and Alzheimer’s disease could also be significantly impacted with her protocol. I also believe that this protocol could have the greatest impact early into the disease, and could very possibly reverse these diseases entirely. Dr. Budwig states, “A Swede has proved that (no brain function) can take place at all without three-fold unsaturated fats. Without any doubt, every function of the brain—and this has been scientifically proven–needs the very easy activation effect of three-fold unsaturated fats.
“The same applies to nerve functions and for regeneration within the muscle after strenuous muscle activity, in the so-called oxidative recovery phase during sleep. This process requires the highly unsaturated, particularly electron-rich fatty acids in flax seed oil. So, when I wish to help a very sick patient, I must first give the most optimal oil I have. My opinion is flax seed oil.”
– Dr. Budwig
Dr. Budwig pointed out in her book that she often took very sick cancer patients from the hospital and had very good results with her protocol, much of the time. I would assume some patients she worked with were too badly damaged by the chemotherapy and radiation treatments. She pointed out that in some of these patients she would start their therapy with an enema of 500 CCs of an oil mixture and “that their subjective awareness of well-being increased immediately.”
She pointed out that many patients could not urinate, produce bowel movements, or when coughing were unable to bring up the mucous, but once the protocol was initiated this started reactivation of the vital functions and the patients immediately began feeling better. The Budwig diet appears to allow cancer cells to start breathing again.
Here are a couple of testimonials I found quite interesting and thought I would share with you. These testimonials were found in Cliff Beckwith’s website:
Dr. Budwig states “What we need in Europe today, in Germany as well as in Switzerland, America, and France, what we really need are electron rich highly unsaturated fats. The moment two unsaturated double links occur together in a fatty acid chain, the effects are multiplied and in the highly unsaturated fats, the so-called “linoleic” acids, there is generated a field of electrons, a veritable electrical charge which can be quickly conducted off into the body, thus causing a recharging of the living substance — especially of the brain and nerves. It is exactly those highly unsaturated fatty acids which play a decisive role in the respiratory functioning of the body. Without these fatty acids, the enzymes in the breath can not function and we asphyxiate, even when given extra oxygen, as for examples in hospitals. The lack of these highly unsaturated fatty acids paralyzes many vital functions. Primarily, it cuts off the air we breath. We can not survive without air and food and we cannot survive without these fatty acids — that was proven long ago.”
Dr. Budwig, in her book, brought up other areas of interest and how electron-rich fats affect other vital functions of the body. I will mention them, but will not go into any detail, as one may purchase her books to learn much more than presented in this paper. The lack of electron rich unsaturated fats affect; respiratory enzyme function — It is basically proven that highly unsaturated fatty acids are the undiscovered decisive factor in achieving the desired effect of cellular respiratory stimulation:
All glands of the body
Brain Function- Including mental and spiritual
Scholastic performance of children
Function of the Heart — Proper firing of the heart
Moral and behavior problems
Human sexual relationships
Formation of tumors
Ingestion of wrong fats — Humans will eat six times their normal amount of food
Dr. Budwig, in her book, also brought up the relationship between the Fats Syndrome, Electrons, Photons, and Solar Energy provided by the Sun.
She pointed out that the sun is an inexhaustible source of energy and an element of life that affects the vital functions of the body. This, in part, is due to the photons in sunlight which are the purest form of energy, the purest wave, and in continual movement. Dr. Budwig states, “electrons are already a constituent of matter, even though they are also in continual movement and that electrons love photons, attracting each other due to their magnetic fields. There is nothing else on earth with a higher concentration of photons of the sun’s energy than man. This concentration of the sun’s energy — very much an iso-energetic point for humans, with their eminently suitable wavelengths — is improved when we eat food which has electrons which in turn attract the electromagnetic waves of sunbeams, of photons.
“A high amount of these electrons which are on the wavelength of the sun’s energy, are to be found, for example, in seed oils. Scientifically, these oils are even known as electron–rich essential highly unsaturated fats. But, when people began to treat fats to make them keep longer, no-one stopped to consider the consequences of this, for the existence and higher development of the human race. These vitally important amounts of electrons, with their continual movement and the wonderful reaction of light, were destroyed.”
Dr. Budwig found when she treated patients and had them lie in the sun she noticed they started feeling much better and became rejuvenated. She referred to the sun as having a stimulating effect on the secretions of the liver, gall bladder, pancreas, bladder and salivary glands. Dr. Budwig also stated “Matter always has its own vibration, and so, of course, does the living body. The absorption of energy must correspond to one’s own wavelength.” It appears apparently that sunlight is absolutely essential for the stimulation effect of the vital functions of the mind and body, contributing to the factors which allow the body to heal itself.
Dr. Budwig mentioned that doctors tell patients and cancer patients to avoid the sun as they can’t tolerate it and that is correct. She says once these patients start on her oil-protein nutritional advice for two or three days which means they have been getting sufficient amounts of essential fats, they can then tolerate the sun very well. She said the patients then tell her how much better they feel as their vitality and vigor is re-stimulated.
The last of the points mentioned by Dr. Budwig, and maybe the most important, is the electrons in our food serve as the resonance system for the sun’s energy and are truly the element of life. Man acts as an antenna for the sun. The interplay between the photons in the sunbeams and the electrons in the seed oils and our foods governs all the vital functions of the body.
This has to be one of the greatest discoveries ever made as this combination promotes healing in the body of chronic and terminal diseases. In her book, Dr. Budwig states “Various highly trained and educated individuals are dismayed and irritated by the fact that serious medical conditions can be cured by cottage cheese and flaxseed oil.”
The mixing of the oil and cottage cheese allows for the chemical reaction to take place between the sulfur protein in the cottage cheese and the oil, which makes the oil water soluble for easy absorption into your cells.
The Budwig Protocol
The mixing ratio is two tablespoons of cottage cheese to one tablespoon of oil. Mix only the amount you are consuming at one time so it is mixed fresh each and every time. One example would be to mix (4) tablespoons of cottage cheese to (2) tablespoons of flax oil, consumed twice daily or more depending on the severity of the health condition one is attempting to address. One should probably start slowly with the oil, maybe just once a day and work their way up letting the body adjust to the protocol. The oil and the cottage cheese must be thoroughly mixed at a low speed, using an Immersion Blender, blending until a creamy texture with no standing oil is achieved.
The mixture should then be immediately consumed.
Do not add anything to the mixture until after it is mixed.
We have always recommended using the immersion [stick or wand like] mixer for the flaxseed oil and cottage cheese. Here is a link to an immersion mixer.
One may want to consider sprinkling a tablespoon or two of freshly ground flaxseed over the top of the freshly mixed flax oil and cottage cheese mixture. Mix this in by hand. This supercharges the protocol. Do not buy pre-ground flax seed as the flax seed goes rancid 15 minutes after grinding. Brown or golden whole flaxseed is available at the health food stores and either will work. You may grind up the fresh flax seed with a small coffee grinder. Store the seeds in the refrigerator and grind fresh each time.
You may also stir in with a spoon 2-3 tablespoons of organic low-fat milk for a creamier mixture. This can be mixed in by hand after the initial blending. The mixture can be flavored differently every day by adding nuts, preferably organic such as pecans, almonds or walnuts (not peanuts), banana, organic cocoa, organic shredded coconut, pineapple (fresh), blueberries, raspberries, cinnamon, or (freshly) squeezed fruit juice. It’s usually best to place the fresh fruit on top of the completed mixture and enjoy as its own meal. Try your best to obtain organic fruit when possible. Many times this can be found frozen when not in season.
Dr. Budwig pointed out that people who are suffering from chronic or terminal disease should work themselves up to consuming 4 – 8 Tbs of the oil daily. Usually, the higher limits 6-8 Tbsp were for people with cancer. She stated people with liver or pancreatic cancer etc, may have to work up very slowly with the oil and possibly only start with 1 teaspoon at a time giving their body time to adjust. Dr. Budwig pointed out that cancer patients once starting the protocol and getting it under control must continue with a maintenance dose to prevent reoccurrence. A maintenance dose is considered (1) Tbsp of the oil per 100 pounds of body weight. The Budwig Diet takes time to work and in the event of cancer, tumors, etc may take 3-6 months to see results. Many other health issues may respond much faster.
Also here is a very good YouTube video which actually shows how to make the flax oil and cottage cheese mixture correctly. When starting the protocol you would not want to make such a large amount at first, as shown in the video.
If you are lactose intolerant you may want to try the following. Since commercial milk is pasteurized, beneficial bacteria and enzymes in the milk and dairy products are destroyed. This has led to a number of people having difficulty in tolerating quark or cottage cheese.
Dairy is an important component in Dr. Budwig's Oil-Protein Diet. Because good substitutes are hard to find, it is worthwhile for those who are lactose intolerant to try different ways of tolerating dairy.
Some possibilities (in no particular order):
Use raw milk and raw milk products if you can get them.
Use goat's milk instead of cow's milk products.
Take the enzyme Lactase with quark or cottage cheese.
The Budwig Diet - Flaxseed Oil and Cottage Cheese - Cancer Tutor https://www.cancertutor.com/budwig/
. 1995 Jan;
Zinc deficiency and activities of lipogenic and glycolytic enzymes in liver of rats fed coconut oil or linseed oil
1Institut für Ernährungsphysiologie der Technischen Universität München, Freising, Germany.
In previous studies, zinc-deficient rats force-fed a diet with coconut oil as the major dietary fat developed a fatty liver, whereas zinc-deficient rats force-fed a diet with linseed oil did not. The present study was conducted to elucidate the reason for this phenomenon. In a bifactorial experiment, rats were fed zinc-adequate or zinc-deficient diets containing either a mixture of coconut oil (70 g/kg) and safflower oil (10 g/kg) ("coconut oil diet") or linseed oil (80 g/kg) ("linseed oil diet") as a source of dietary fat, and activities of lipogenic and glycolytic enzymes in liver were determined. In order to ensure adequate food intake, all the rats were force-fed. Zinc-deficient rats on the coconut oil diet developed a fatty liver, characterized by elevated levels of triglycerides with saturated and monounsaturated fatty acids. These rats also had markedly elevated activities of the lipogenic enzymes acetyl-CoA carboxylase, fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and citrate cleavage enzyme, whereas activities of malic enzyme and glycolytic enzymes were not different compared with zinc-adequate rats on the coconut oil diet. In contrast, rats receiving the linseed oil diet had similar triglyceride concentrations regardless of zinc status, and activities of lipogenic enzymes and glycolytic enzymes were not different between the two groups. Zinc-deficient rats fed either type of dietary fat exhibited statistically significant correlations between activities of FAS, G6PDH, 6PGDH and concentrations of saturated and monounsaturated fatty acids in liver.(ABSTRACT TRUNCATED AT 250 WORDS)
在先前的研究中，缺锌的老鼠强迫进食以椰子油为主要饮食脂肪的饮食，从而形成脂肪肝，而缺锌的老鼠强迫进食以亚麻籽油为饮食的脂肪肝。进行本研究以阐明这种现象的原因。在一项双因素实验中，给大鼠饲喂锌含量充足或锌缺乏的日粮，其中含有椰子油（70克/千克）和红花油（10克/千克）（“椰子油饮食”）或亚麻子油（80 g / kg）（“亚麻籽油饮食”）作为饮食脂肪的来源，并确定了肝脏中脂肪形成和糖酵解酶的活性。为了确保足够的食物摄入，所有大鼠都被强制喂养。椰子油饮食中缺锌的老鼠发育了脂肪肝，其特征是甘油三酸酯与饱和和单不饱和脂肪酸含量升高。这些大鼠的脂肪生成酶乙酰辅酶A羧化酶，脂肪酸合酶（FAS），葡萄糖6磷酸脱氢酶（G6PDH），6-磷酸葡萄糖酸脱氢酶（6PGDH）和柠檬酸裂解酶的活性也显着升高，而苹果酸的活性椰子油饮食中与锌充足的大鼠相比，酶和糖酵解酶没有差异。相比之下，接受亚麻籽油饮食的大鼠无论锌的状态如何，甘油三酯的浓度都相似，两组之间的脂肪酶和糖酵解酶活性没有差异。饲喂两种膳食脂肪的缺锌大鼠在肝中FAS，G6PDH，6PGDH的活性与肝脏中饱和和单不饱和脂肪酸的浓度之间显示出统计学显着的相关性（摘要截断为250个字） Zinc deficiency and activities of lipogenic and glycolytic enzymes in liver of rats fed coconut oil or linseed oil - PubMed
Low temperature oxidation of linseed oil: a review
Juita, Bogdan Z Dlugogorski, Eric M Kennedy & John C Mackie
Fire Science Reviews volume 1, Article number: 3 (2012) Cite this article
This review analyses and summarises the previous investigations on the oxidation of linseed oil and the self-heating of cotton and other materials impregnated with the oil. It discusses the composition and chemical structure of linseed oil, including its drying properties. The review describes several experimental methods used to test the propensity of the oil to induce spontaneous heating and ignition of lignocellulosic materials soaked with the oil. It covers the thermal ignition of the lignocellulosic substrates impregnated with the oil and it critically evaluates the analytical methods applied to investigate the oxidation reactions of linseed oil.
Initiation of radical chains by singlet oxygen (1Δg), and their propagation underpin the mechanism of oxidation of linseed oil, leading to the self-heating and formation of volatile organic species and higher molecular weight compounds. The review also discusses the role of metal complexes of cobalt, iron and manganese in catalysing the oxidative drying of linseed oil, summarising some kinetic parameters such as the rate constants of the peroxidation reactions.
With respect to fire safety, the classical theory of self-ignition does not account for radical and catalytic reactions and appears to offer limited insights into the autoignition of lignocellulosic materials soaked with linseed oil. New theoretical and numerical treatments of oxidation of such materials need to be developed. The self-ignition induced by linseed oil is predicated on the presence of both a metal catalyst and a lignocellulosic substrate, and the absence of any prior thermal treatment of the oil, which destroys both peroxy radicals and singlet O2 sensitisers. An overview of peroxyl chemistry included in the article will be useful to those working in areas of fire science, paint drying, indoor air quality, biofuels and lipid oxidation.
The drying rate of linseed oil is too slow for convenient applications, necessitating the addition of metallic salts (drying agents) to accelerate the drying process (Mallégol et al.2000). Unfortunately, in the presence of lignocellulosic fuels, such as cotton fibres, these agents may induce the fuel’s self-heating and autoignition. This dangerous side effect of the oil has been known to fire investigators for almost 200 years (Abraham1996). Several cases of fire have been reported; in particular those induced by improperly disposed rags soaked with linseed oil. Typical ignition scenarios involve waste baskets filled with disposed cotton rags used to clean paint brushes.
Linseed oil has the capacity to form a continuous film with good optical and mechanical properties after being spread out in a thin layer (Lazzari & Chiantore1999). It will cure in air without using a catalyst, although slowly (Marshall1986). The double bonds of the unsaturated acids in the oil react with oxygen in air and with one another to form a polymeric network (Lazzari & Chiantore1999; Stava et al.2007) that determines the drying power of such oils (Lazzari & Chiantore1999), resulting in the liquid layer evolving to a solid film (Roberfroid & Calderon1995; Marshall1986). Thus, this hardening process arises as a result of the autoxidation followed by cross-linking polymerisation (Lazzari & Chiantore1999; Fjällström et al.2002; Tanase et al.2004). The formation of cross linked structures essentially consists of the intermolecular coupling of radicals originated by decomposition of the relatively unstable peroxide groups (Lazzari & Chiantore1999). The drying reaction of linseed oil continues for many years even when the oil film seems to completely dry in a few days (Lazzari & Chiantore1999). However, the presence of glycerides as plasticisers can moderate the hardening process (Lazzari & Chiantore1999). The oil can gain up to 40% of its original weight during oxidation in the drying process with some weight loss due to the decomposition and disappearance of volatile compounds during oxidation reaction (Fjällström et al.2002).
Metals, light, heat and enzymes accelerate the oxidation of unsaturated acids in the oil, while antioxidants inhibit oxidation. Oxidation of fatty acids occurs through autoxidation or photo-oxidation. The rate of autoxidation depends on the presence of pro-oxidants (i.e., oxidising agents), antioxidants, temperature and the dissolved oxygen (Belhaj et al.2010). Oleic acid, as a monounsaturated acid, can be oxidised only at elevated temperatures, while polyunsaturated acids such as linolenic and linoleic acids undergo rapid oxidation even at room temperature (Kumarathasan et al.1992). Allyl hydroperoxides, chemical moieties containing both allyl (−CH = CH–CH2–) and hydroperoxide (−OOH) groups as in –CH = CH–CH(OOH)–, constitute the primary oxidation products. The double bonds remain but may have changed position and/or configuration from their original form during the oxidation reaction, with the formation of hydroperoxides. The schematic diagram in Figure 2 illustrates further changes affecting the hydroperoxides (Gunstone1996).
Kinetics and reaction mechanisms of oil oxidation
Reaction pathways involved in oxidation
Mechanism of radical chain reactions
The essential processes in the oxidation, involving radical chain reactions, consist of primary initiation, where radicals are formed from the parent molecules, propagation, which conserves the number of radicals, termination that removes the radicals, branching, which multiplies the number of radicals and secondary initiation that forms new radicals from a stable intermediate product (Pilling1997). The rate of oxidation is mostly influenced by the rates of branching and termination.
Antunes et al. (Antunes et al.1996) reported that the primary initiation agents in the basic scheme of lipid peroxidation consist of hydroxyl, perhydroxyl and α-tocopheroxyl radicals. Reactions (7) to (9) describe the abstraction reactions by those radicals. Hydroxyl radical reacts nonselectively with organic compounds (Antunes et al.1996), while the less reactive peroxyl radical abstracts hydrogen selectively at the bis-allylic methylene bridge (Bors et al.1987). Pentadienyl radical, produced by this hydrogen abstraction, has an unpaired electron distributed over five carbon atoms (Bors et al.1987; Gardner1989).
Since the addition of ground state O2 (i.e., triplet oxygen) to biomolecules is spin forbidden, the direct reaction proceeds very slowly with the rate constant of less than 10-5 M-1 s-1 (Miller et al.1990). Thus the critical step in the oxidation of biomolecules, in the presence of atmospheric oxygen, corresponds to the formation of the initial radicals.
The initiation reaction of the oil oxidation can proceed through the formation of singlet oxygen by photosensitised oxidation (Choe & Min2006). Singlet oxygen could be generated from triplet oxygen in chlorophyll photosensitisation, inducing the formation of 2-pentyl furan, trans-2-heptenal and 1-octen-3-ol in linoleic acid samples (Lee & Min2010). Chlorophyll, commonly found in vegetable oils, serves as a photosensitiser. Photosensitisers absorb light energy very rapidly and convert the singlet state to excited triplet state sensitisers. The reaction of these excited sensitisers with triplet oxygen produces singlet oxygen (Choe & Min2006; Min & Boff2002; Rawls & Santen1970). The reactions involving singlet oxygen are probably responsible for initiating the self-heating of linseed oil. While autoxidation incorporates the formation of alkyl radicals, photosensitised oxidation involves the reaction between singlet oxygen and double bonds without the formation of these alkyl radicals to generate hydroperoxides at the double bonds (Choe & Min2006).
Reactions with singlet oxygen exhibit low activation energies, 0 to 25 kJ mol-1, allowing facile oxidation of biomolecules (Lee & Min2010). Different hydroperoxides arise from reactions involving singlet and triplet oxidation. The former generates C9, C10, C,12 and C13 hydroperoxides and the later, known as autoxidation, forms C9 and C13 hydroperoxides (Lee & Min2010).
Propagation reactions proceed through four dominant pathways: atom transfer, electron transfer, addition and scission reactions. Abstraction of hydrogen represents the common reaction of atom transfer in the propagation step (Roberfroid & Calderon1995), for example the abstraction of hydrogen from fatty acid chain by peroxyl radical (Halliwell & Gutteridge2008). The combination of molecular oxygen with an electron to form superoxide characterises the second type of propagation via electron transfer (Roberfroid & Calderon1995). In this reaction, an electron transfers from a transition metal ion to a peroxide compound. The third pathway operates in the lipid peroxidation and involves the addition of oxygen to the alkyl radical (Roberfroid & Calderon1995). This reversible reaction of oxygen with an initial carbon centred radical to form a peroxyl radical constitutes the most important pathway (Antunes et al.1996). It is controlled by oxygen migration with the apparent activation energy of 24 kJ mol-1 in unsaturated lipids (Zhu & Sevilla1989). Kinetically, it is a very fast pathway, hence the concentration of peroxyl radicals is much higher than alkyl radicals (Hanson et al.2004; Kubow1992). The last of the four dominant propagation pathways involves the transformation of peroxyl radicals into allylic and pentadienyl radicals (Zhu & Sevilla1989).
Peroxyl radicals can abstract hydrogen to form hydroperoxides. Hydrogen abstraction by radicals is least favourable from alkanes, more favourable from a monoallylic position in alkenes and most favourable from a double allylic position, as a consequence of decreasing C-H bond dissociation energies (Oyman et al.2005a). In addition to the hydrogen abstraction from substrate, peroxyl radicals also play an important role in the abstraction of the weakly bonded α hydrogen atom of the hydroperoxide product (Figure 16) as described in reactions (11) and (12). The decomposition of R-αH •OOH (αH refers to the weakly bonded α hydrogen) to Q = O (Q denotes R-αH) and •OH releases around 126 kJ mol-1. The hydroxyl radical rapidly abstracts a hydrogen atom from substrate and this reaction is also exothermic (Hermans et al.2007).
Position of weakly bonded α-hydrogen atom in hydroperoxide compound.
Full size image
Moreover, peroxyl radical could undergo cyclisation reactions by the intramolecular arrangement through four and five membered rings. Quantum chemical calculations identified low energy pathways for the decomposition of cyclic peroxides into aldehydes and ketonic species (Juita et al.2011e).
An alkoxyl radical forms as the result of the decomposition of lipid hydroperoxide by transition metals such as Fe2+. These radicals can abstract hydrogen from unsaturated fatty acid or add to double bonds to form carbon centred radicals (Antunes et al.1996). Heteroatom-centred radicals display higher ratios of hydrogen abstraction to addition than carbon-centred radicals. For instance, an alkoxyl radical prefers to abstract hydrogen over addition due to the difference in exothermicity between the two reactions of 30 kJ mol-1 (Moad & Solomon1995).
The termination reactions proceed through the radical-radical recombination or cross linking reaction. The reaction between two peroxyl radicals predominates over reaction between carbon-centred radicals and between a carbon-centred radical and a peroxyl radical (Antunes et al.1996). Recombination of the carbon-centred radicals has an apparent activation energy of 40 kJ mol-1 (Zhu & Sevilla1989). The rate constant for the termination reaction depends on the chain lengths of the two radicals and it is affected by the diffusion mechanisms (Moad & Solomon1995). The primary radicals involved in the polymerisation reaction are hydroxyl and alkoxyl radicals (Allen & Patrick1974). Cobalt(II) complexes, as the chain transfer agents, can catalyse the polymerisation reaction through the combination of metal with carbon-centred radicals (Moad & Solomon1995).
The addition of oxygen to a free radical and the termination step by crosslinking involve exothermic processes, while decomposition of hydroperoxides constitutes an endothermic process. The addition of dryers and metal alkoxides can decrease the onset temperature of the reaction exotherm. This affects the extent of curing, as measured by the indentation hardness of the drying films (Tuman et al.1996).
In the autoxidation reaction of cyclohexane (CyH), which has similarity with that of linseed oil, the major chain initiation reaction is the homolytic dissociation of CyOOH into CyO• and •OH radicals, while the major termination step is the reaction of two peroxyl radicals into CyOH, Q = O and O2. The hydrogen abstraction reaction by peroxyl radical represents the rate determining step in the chain propagation reaction. The addition of oxygen to the cyclohexane radical is diffusion controlled under sufficient oxygen pressure (Hermans et al.2006).
Isomerisation reactions and hydroperoxides as important intermediates
Thermal decomposition of peroxides proceeds mostly through the homolytic fission of the O-O bond (Swern1972), as a consequence of the low dissociation energy of this bond. Cobaltous ion assists the decomposition of hydroperoxide into alkoxyl radical (Yamada et al.1984). The rate of hydroperoxide decomposition increases at elevated pH (Rolewski et al.2009). Hydroperoxides formed during oxidation of lipid represent stable intermediates, therefore, their detection indicates the initial lipid oxidation (Rolewski et al.2009). The amount of monohydroperoxides decreases with increasing temperature due to the faster degradation of monohydroperoxides (Haslbeck et al.1983). Linseed oil produces hydroperoxide at abundances one order of magnitude higher than linoleic acid due to a large modal content of linolenic acid in linseed oil (Rolewski et al.2009).
Table 7 illustrates different hydroperoxide species that form from oxidation of methyl esters of oleic, linoleic and linolenic acids. For each methyl ester, the product species differ by the position of double bonds and the location of OOH attachment. Oxidation of linoleic esters produces almost exclusively 9- and 13-hydroperoxides, which are categorised as outer hydroperoxides. Inner hydroperoxides such as 10- and 12-hydroperoxides arise in minor amounts, possibly as a consequence of other reaction pathways, leading to formation of cyclic peroxides (i.e., endoperoxides) and resulting in smaller amounts of inner hydroperoxides, as illustrated in the following scheme (Gunstone1996; Roberfroid & Calderon1995; Halliwell & Gutteridge2008) Scheme 4.
Formation of cyclic peroxides from inner hydroperoxides.
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Table 7 Major hydroperoxides emitted during autoxidation of methyl oleate, linoleate and linolenate (Gunstone 1996 )
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This cyclic peroxide forms when a peroxyl radical attacks another double bond in the same compound (Halliwell & Gutteridge2008).
Oxygen concentration influences the mechanism of peroxidation. For instance, self reaction of carbon centred radicals is more likely to occur at a very low concentration of oxygen (Halliwell & Gutteridge2008). As a consequence of this sensitivity, many complex mixtures of compounds can be produced from the decomposition of lipid peroxides, involving epoxides, saturated and unsaturated aldehydes, ketones and hydrocarbons (Halliwell & Gutteridge2008).
There are literature reports on the mechanistic differences between the oxidation of conjugated and non-conjugated fatty acids. The H abstraction rate of non-conjugated fatty acid is faster than that of the conjugated acids. This is because of resonance stabilisation of conjugated double bonds and also the presence of trans double bonds (Muizebelt et al.2000). For example, conjugated ethyl linoleate is estimated to be 12–17 kJ mol-1 more stable than non-conjugated ethyl linoleate (Muizebelt et al.2000). For comparison, radicals arising from H abstraction from non-conjugated fatty acids are stabilised by resonance. This results in lower abundance of peroxide species present in oils containing conjugated fatty acids (Oyman et al.2005a). Polymerisation reactions can occur by direct addition of free radicals to the conjugated double bonds and by radical recombination (Oyman et al.2005a). Conjugated fatty acids tend to favour radical addition to double bonds, whereas non-conjugated species prefer to enter into radical recombination reactions (Muizebelt et al.2000).
A cis, non-conjugated diene structure changes to a cis,trans conjugated hydroperoxide during autoxidation of methyl linoleate or methyl linolenate (Hendriks et al.1979). A similar transformation also takes place during hydrogenation of unsaturated lipids. As for the autoxidation reactions, the ratio of cis to trans as the result of the partial hydrogenation of oil depends on the initial oil composition, catalyst and temperature (De Oliveira Vigier et al.2009).
The isomerisation reaction of hydroperoxides during oxidation of linseed oil is similar to the mechanism that occurs in isoprene oxidation. Peeters et al. studied the addition of hydroxyl radical to isoprene and found the major adducts to be 1-OH (about 60%) and 4-OH (around 30%). Trans isoprene is the more stable and dominant structure which releases 159 kJ mol-1 of energy upon OH addition to form around 50% trans- and 50% cis-1-OH. The reaction entails the formation of an allyl resonance configuration permitting addition at two positions. These activated adducts can undergo cis-trans isomerisation with the barriers of only 59–63 kJ mol-1. The addition of oxygen to the OH-isoprene occurs rapidly at two addition sites, as illustrated in the third row of Figure 17. The substitution at a β site enables the internal rotation of the –CH = CH2 group, forming both cis and trans OH-isoprene radicals. Addition to the α sites induces the formation of E- and Z-substituted alkenes. β-OH-peroxyl radicals undergo the 1,5-H shift of the OH-hydrogen to form a β-HOO-alkoxyl radical, which displays a very low barrier to further decomposition. Additionally, the Z-1-OH-4-OO• can isomerise via 1,6-H-shift of the weakly bonded α-OH hydrogen to the peroxyl radical site by overcoming a barrier of 75 kJ mol-1 (Peeters et al.2009; Stavrakou et al.2010).
Low temperature oxidation of linseed oil: a review | Fire Science Reviews | Full Text