Oxidation in the body

This synthesis was the first step toward industrial vitamin production, which began in 1936. The synthetic product was shown to have the same biological activity as the natural substance. It is reversibly oxidized in the body to dehydro-L-ascorbic acid (3) (L-// fi (9-2,3-hexodiulosonic acid y-lactone), a potent antiscorbutic agent with hiU vitamin activity. In 1937, Haworth and Szent-Gyn rgyi received the Nobel Prize for their work on vitamin C. 

Amino acids are the building blocks of proteins, which have long chainlike molecules. They are oxidized in the body to urea, carbon dioxide, and liquid water. Is this reaction a source of heat for the body Use the information in Appendix 2A to predict the standard enthalpy of reaction for the oxidation of the simplest amino acid, glycine (NH2CH2COOH), a solid, to solid urea (H2NCONH2), carbon dioxide gas, and liquid water ... 

We then sought an independent method of proving the /9-oxidation theory.1 This consisted in synthesizing w-fluoro compounds which contained the skeleton of the toxic members, but which could not undergo /9-oxidation in the body. If these new compounds had been toxic, the /9-oxidation theory would have had to be abandoned. Actually they were non-toxic compared with the parent acid , and so excellent support, of a kind hitherto not considered, was obtained. 

Liebig. Carbohydrate, fat and protein oxidized in the body to release defined amounts of energy. 

While the pH of blood must be maintained within strict limits, the pH of urine can vary. The sulfur in foods, such as eggs, is oxidized in the body and excreted in the urine. Does the presence of sulfide ions in urine tend to increase or decrease the pH Explain. 

Ethanol is produced as a more environmentally benign fuel. The systematic effect of ethyl alcohol differs from that of methyl alcohol. Ethyl alcohol is rapidly oxidized in the body to carbon dioxide and water, and in contrast to methyl alcohol no cumulative effect occurs. Ethanol is also a preferred alcohol in the transportation sector compared to methanol because it is derived from agricultural products and is renewable and biologically less objectionable in the enviromnent. 

Pure 100% ethyl alcohol is a colorless, volatile hquid with a pungent taste. One hundred-proof alcoholic drinks are about 50% ethanol. When consumed, ethanol is a depressant and may be habit-forming. It rapidly oxidizes in the body, but even small amounts cause dizziness, nausea, headaches, and loss of motor control. Proof was how whiskey salesmen of the Old West demonstrated that their product was potent. They would place some gunpowder in a tin dish and then pour on some of their whiskey. If a match would ignite the mixture, this was claimed to serve as 100% proof of the whiskeys quality. It just happens that 100-proof whiskey is about 50% ethanol. 

Generally, phthalates are metabolized and excreted quickly and do not accumulate in the body [23]. Ingested phthalate diesters are initially hydrolyzed in the intestine to their corresponding monoester, which is then absorbed [24], and could be further oxidized in the body. 

Carotene (Section 2-1) has vitamin A activity and apparently is oxidized in the body at the central double bond to give one mole of vitamin A. 

What are the metabolic products of ethanol oxidation in the body How does the rate of ethanol metabolism compare to that of methanol metabolism ... 

Dr. Martin Pall of Washington State University uncovered the neurological biochemical processes that underlie MCS, and demonstrated a link to processes that are also relevant to chronic fatigue syndrome. He described the increased permeability of the blood-brain barrier as a result of exposure to certain substances and as a result of increased peroxynitrite level. The more this barrier disintegrates, the more chemical substances are able to directly enter the brain and the more sensitive a person becomes. Increased levels of nitric oxide in the body in turn influence the enzymes responsible for breaking down chemical substances (P450 enzyme). He published an article about his model, tide Elevated Nitric Oxide/Per-oxynitrite Theory of Multiple Chemical Sensitivity Central Role of N-Methyl-d-Aspartate Receptors in the Sensitivity Mechanism, in Environmental Health Perspectives. It can be read online at www.ehponline.org/members/ 2003/5935/5935.html. 

Primary amines are oxidized in the body by monoamine oxidase (MAO). MAO converts the amine to an imine, which is hydrolyzed to yield an aldehyde and ammonia. One function of MAO is to regulate the levels of the neurotransmitters serotonin and norepinephrine. Monoamine oxidase inhibitors prevent the oxidation (and inactivation) of these neurotransmitters, thereby elevating mood. MAO inhibitors were the first antidepressants, but they are used sparingly now because of numerous side effects. 

Glucose is oxidized in the body to give energy. What are the waste... 

Respiratory measurements alone can be used to determine the amounts of carbohydrate and fat oxidized in the body over a given period. These amounts can be more accurately determirted by including data from urinary nitrogen measurements in the calculations. According to Frajm (19S3), the grams of carbohydrate (c) and fat y) oxidized per minute can be calculated from the formulas... 

Further studies on the metabolism of related compounds then revealed that the methyl group on these compounds was oxidized in the body to a hydroxymethyl group and that this was in fact the active compound. The methyl group on III was replaced with a hydroxymethyl group to give oxamniquine (Fig. 7.43) which was... 

Ethylene glycol, which is widely used as an antifreeze for automobile radiators, upon ingestion causes depression of the CNS, metabolic acidosis, and severe renal damage. Its oxidation in the body requires the action of alcohol dehydrogenase ... 

A small amount of elemental Hg vapor is excreted unchanged in exhaled air, sweat, saliva, feces, and urine (Cherian et al. 1978). Only small amounts of elemental Hg can be detected in the urine (Stopford et al. 1978) and exhaled air (Hursh et al. 1976). Excretion via sweat and saliva is usually minimal. The hair-life for whole-body Hg excretion was 58 days in humans (Hursh et al. 1976). Elemental Hg is also oxidized in the body to mercuric Hg, which is then excreted in the feces and urine. That is demonstrated by the observation that, after exposure to Hg... 

Virtually no food is in thermodynamic equilibrium. We all know that food is a source of energy and that, for example, one gram of carbohydrate yields on oxidation in the body about 17 kJ (about 4kcal). Assuming the elementary reaction to be... 

Much has been written concerning the value of aloohol ns a food. If it have any value ns such, it is os a producer of heat and force by its oxidation in the body experiments have failed to show at more tl a small percentage (16 per cent, in 24 hrs.) of medium doses of alcohol in-... 

Sucrose (C12H22O11, table sugar) is oxidized in the body by O2 via a complex set of reactions that ultimately produces C02(g) and H20(g) and releases 5.64X 10 kJ/mol sucrose. 

Gain of Electrons = Reduction. Compounds are oxidized in the body in essentially three ways (1) the transfer of electrons from the compound as a hydrogen atom or a hydride ion, (2) the direct addition of oxygen from O2, and (3) the direct donation of electrons (e.g., Fe Fe ) (see Chapter 5). Fuel oxidation involves the transfer of electrons as a hydrogen atom or a hydride ion and, thus, reduced compounds have more hydrogen relative to oxygen than the oxidized compounds. Consequently, aldehydes are more reduced than acids, and alcohols are more reduced than aldehydes. 

Estrogens induce tumors in animals, a fact that probably depends on the formation of catechol-type A rings. Arene oxides and/or semiquinones may then be formed, which react as cross-linkers in the same way as polycyclic hydrocarbons, such as benzopyrene, which is oxidized in the body to a diol-epoxide. Electroreduction of the corresponding ortho-quimm to the semiquinone radical, the same product that would be formed upon oxygen oxidation of the catechol, in the presence of adenine, does indeed produce a covalent adduct in 14% yield (Scheme 3.4.5)... 

On the other hand, if alcohol be oxidized in the body, we should expect, in the absence of violent muscular exercise, an increase in temperature, and the appearance in the excreta of some product of oxidation of alcohol aldehyde, acetic acid, carbon dioxid, or water, while the elimination of nitrogenous excreta, urea, etc., would remain unaltered or be diminished. While there is no doubt that excessive doses of alcohol produce a diminution of body temperature, the experimental evidence concerning the action in this direction of moderate doses is conflicting and incomplete. Of the products of oxidation, aldehyde has not been detected in the excreta, and acetic acid only in the intestinal canal. The elimination of carbonic acid, as such, does not seem to be increased, although positive information upon this point is-wanting. If acetic acid be produced, this would form an acetate, which in turn would be oxidized to a carbonate, and eliminated. 

Under normal conditions, and with food not too rich in starch and saccharine materials, the quantity of sugar eliminated as such is exceedingly small. It is oxidized in the body, and the ultimate products of such oxidation eliminated as COa and HjO. Whether or no intermediate products are formed, is still uncertain the ijrobability, however, is that there are. The oxidation of sugar is impeded in diabetes. 

Pure methyl alcohol is poisonous. It differs from ordinary grain alcohol in that it is not completely oxidized in the body to carbon dioxide and water, which are eliminated. It is converted largely into formic acid. In comparatively small doses it produces blindness. Repeated exposure to the vapor of the alcohol mixed with air produces the same result. 

---