Md. Wasim Aktar asked:


1. Introduction

In the aerobic environment, the most dangerous by product are the species of reactive oxygen. The role of antioxidants is to detoxify reactive oxygen intermediates (ROI) in the body. Over the past several years, nutritional antioxidants have attracted considerable interest in the popular press as potential treatment for a wide variety of disease states, including cancer and other causes e.g. cancer, chronic inflammatory diseases and aging (Delany L. 1993).

Naturally occurring inhibitors of oxidation in food generally originate from plant-based materials. The active components, namely phenolics and polyphenolics, including tocopherols, are secondary plant metabolites and are first derived from phenylalanine and in certain cases and in some plants from tyrosine. The resultant phenylpropanoids may then undergo further transformation to yield benzoic acid derivatives as well as flavonoids, isoflavons, and other complex polyphenols. Thus, natural food phenolics are present as a complex mixture of compounds that provide a cocktail of many active components present in the free, esterified, glycosylated and bound forms (Shahidi and Naczk, 1995). The potency of preparations is therefore dictated by their chemical structures and governed by the hydrophilic-lipophilic balance (HLB) of the participating molecules in a concentration- and system-dependent manner. Thus, the mode of action of natural antioxidants may involve multiple mechanisms, depending on the source material and possible presence of synergists and antagonists.

In order to use any antioxidant preparation in food, it must be safe, easy to incorporate, effective at low concentrations, with no undesirable odour, flavour or colour, heat stable, nonvolatile and with good carry through properties and cost-effective. In addition, presence and possible effects of antagonists must be carefully considered, as an antioxidant may become a prooxidant in the presence of certain other molecules. As an example, chlorophylls may overwhelm the antioxidant effect of phenolics due to photosensitized oxidation and transition metal ions such as those of iron and copper may render conditions that favour oxidation. Synergism among different phenolic antioxidants and between phenolics and non-phenolics should be considered in all application areas.

Definition

Free radicals are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules. Once formed these highly reactive radicals can start a chain reaction. Their chief danger comes from the damage they can do when they react with important cellular components such as DNA, or the cell membrane. Cells may function poorly or die if this occurs. To prevent free radical the body has a defence system of antioxidants.

An antioxidant is a substance that when present in low concentrations relative to the oxidizable substrate significantly delays or reduces oxidation of the substrate (Halliwell, 1995).

Antioxidants get their name because they combat oxidation. They are substances that protect other chemicals of the body from damaging oxidation reactions by reacting with free radicals and other reactive oxygen species within the body, hence hindering the process of oxidation. During this reaction the antioxidant sacrifices itself by becoming oxidized. However, antioxidant supply is not unlimited as one antioxidant molecule can only react with a single free radical. Therefore, there is a constant need to replenish antioxidant resources, whether endogenously or through supplementation.

2. Review of Literature

Qin Yan Zhu et. al.(2001) studied antioxidant property of oolong tree. Inhibitory effect on FeCl2/ H2O2 – induced damage and the inhibitory effect on erythrocyte hemolysis of an oolonge tea extract (OTE) were evaluated. The OTE was found to have strong antioxidant activity in all model system. When OTE was separated into fractions according to molecular weight it was found that fraction with higher amount of phenolic compound (with low molecular weight) have strong antioxidative activity.

Yi Fang Chu and Xianzona Wu (2002) reported that increased consumption of fruits and vegetables containing high levels of phytochemicals have been recommended to prevent chronic diseases related to oxidative stress in human body. 10 common vegetables were selected. The study showed that Red peeper had highest total antioxidant activity followed by Broccoli, Carrot, Spinach, Cabbage, Onion, Potato etc.

Jie Sun and Yi Fang (2002) reported that consumption of fruit & vegetable associated with reduced risk to Chronic disease due to present of antioxidant. According to them vitamin C is the major antioxidant in fruit.

Jeong- Chae Lee (2002) assessed an ethanol extract of stem of opuntia to determine the mechanism of its antioxidant activities. The ethanol extract exhibited a concentration dependent inhibition of linoleic acid oxidation.

Keni Chi Ya na Gimoto et. al. (2002) investigated the antioxidant activity of column chromatographic fractions obtained from brewed coffee to find antioxidant and to assess benefits of coffee drinking. Coffee contain many antioxidant and consumption of antioxidant rich brewed coffee may inhibit disease caused by oxidative damage.

Anaberta Cardadose et.al. (2003) showed that fraction extracted with ethyl acetate have antioxidant activity with potent free radical scavenging activity.

Joon Hee Lee et. al. (2003) reported that Muscadine Grapes and its winary bi product have antioxidant capacity.

Kizhiyedathu et. al. (2003) reported that extract obtained from sesame cake and oil have free radical scavenging capacity i.e. antioxidant property.

K.S. Shivashankara and Seiichiro Isobe (2004) reported that if greenhouse- grown tree ripe ( TR) and mature green ( MG) mangoes (cv. Irwin) were exposed to high electric field treatment before 20 and 30 days of storage at 5O C. MG fruits were allowed to ripen at room temperature after low- temperature storage and antioxidant capacity were estimated before and after the storage period. Antioxidant capacity of fruits remained unchanged up to 20 days of storage period and decreased thereafter. Antioxidant capacity of fruits was significantly correlated only to ascorbic acids.

Joseph O. Kuti et.al. (2004) reported that total phenolics and antioxidant capacity were higher in raw that in cooked leaf extracts. Cooking reduced antioxidant activity. The results of their study indicate that tree spinach leaves are a rich source of natural antioxidants.

Mahinda Wella singh and Kirk Parkin (2004) studied a broad range of antioxidant activities in crude extract of beet root tissues. Betalain pigment have been shown to posses various antioxidant function.

3. Classification of antioxidants

Table 1. Classification of antioxidants based on their roles

Enzymes Antioxidant Role Remarks

Superoxide dismutase (SOD)

Mitochondrial

Cytoplasmic

Extracellular Dismutates O2• to H2O2

Contains Manganese (Mn.SOD)

Contains Copper & Zinc (CuZnSOD)

Contains Copper (CuSOD)

Catalase Dismutates H2O2 to H2O Tetrameric hemoprotein present in peroxisomes

Glutathione peroxidase (GSH.Px) Removes H2O2 and lipid peroxides Selenoproteins (contains Se2+)

Primarily in the cytosol also mitochondria

Uses GSH

Vitamins Alpha tocopherol Breaks lipid peroxidation

Lipid peroxide and O2• and •OH scavenger Fat soluble vitamin

Beta carotene Scavenges •OH, O2•and peroxy radicals

Prevents oxidation of vitamin A

Binds to transition metals

Fat soluble vitamin

Ascorbic acid Directly scavenges O2•, •OH, and H2O2

Neutralizes oxidants from stimulated neutrophils

Contributes to regeneration of vitamin E

Water soluble vitamin

Table 2.Classification Of antioxidants based on their sources

Source Material Example Antioxidant

Vegetable Oils

Soybean oil Tocopherols

Tropical Oils

Palm oil Tocotrienols

Plant Oils

Palm oil Carotenoids

Herbs and Spices

Rosemary and Sage Complex phenolics

Cereals

Wheat and buckwheat Flavenoids

Legumes

Soybean Isoflavones

Oil Seeds Canola and Mustard Phenolic acids & Phenylpropanoids

Teas Green Tea Catechins and Polyphenols

Fruit skin and seeds Grape seed and skin Polyphenols and Tannins

4. Antioxidant chemistry of some vitamins

4.1 Alpha tocopherol (vitamin E)

Vitamin E -2D structure - C26H44O2

4.1.1 Nomenclature

It is the major lipid soluble antioxidant found in cells. The name originated in the early 1920s when vegetable oil was discovered to restore fertility in rats. This unknown substance was designated vitamin E by Sure in 1924.The term tocopherol was first used by Evans. Because this compound permitted an animal to have offspring, he named it tocopherol from the Greek word tokos, meaning childbirth, and added the verb phero, meaning to bring forth. To indicate the alcohol nature of the molecule, ol was added to the ending.

Vitamin E is a generic term that includes all entities that exhibit the biological activity of natural vitamin E, d-alpha-tocopherol. In nature, eight substances have been found to have vitamin E activity: d-alpha-, d-beta-, d-gamma- and d-delta-tocopherol (which differ in methylation site and side-chain saturation (Kellof et al. 1996); and d-alpha-, d-beta-, d-gamma- and d-delta-tocotrienol. Also, the acetate and succinate derivatives of the natural tocopherols have vitamin E activity, as do synthetic tocopherols and their acetate and succinate derivatives.

Of all these, d-alpha-tocopherol has the highest biopotency, and its activity is the standard against which all the others must be compared. It is the predominant isomer in plasma.

4.1.2 Source and Nature

Vitamin E is an essential nutrient that functions as an antioxidant in the human body. It is essential, by definition, because the body cannot manufacture its own vitamin E and thus it must be provided by foods and supplements.

Tocopherols are present in oils, nuts, seeds, wheat germ and grains. Absorption is believed to be associated with intestinal fat absorption. Approximately 40% of the ingested tocopherol is absorbed. Most tocopherols enter the blood via lymph where they are associated with chylomicrons. Vitamin E was shown to be stored in adipose tissue. Phospholipids of the mitochondria & endoplasmic reticulum & plasma membranes possess affinities for alpha tocopherol & the vitamin tends to concentrate in these sites.

4.1.3 Mechanisms of Action

Vitamin E is more appropriately described as an antioxidant than a vitamin. This is because, unlike most vitamins, it does not act as a co-factor for enzymatic reactions.

Also, deficiency of vitamin E does not produce a disease with rapidly developing symptoms such as scurvy or beriberi. Overt symptoms due to vitamin E deficiency occur only in cases involving fat mal absorption syndromes, premature infants and patients on total parenteral nutrition. The effects of inadequate vitamin E intake usually develop over a long time, typically decades, and have been linked to chronic diseases such as cancer and atherosclerosis.

Hence, its main function is to prevent the peroxidation of membrane phospholipids, and avoids cell membrane damage through its antioxidant action. The lipophilic character of tocopherol enables it to locate in the interior of the cell membrane bilayers (Halliway and Getteridge, 1992; Borg, 1993). Tocopherol-OH can transfer a hydrogen atom with a single electron to a free radical, thus removing the radical before it can interact with cell membrane proteins or generate lipid peroxidation. When tocopherol-OH combines with the free radical, it becomes tocopherol-O•, itself a radical. When ascorbic acid is available, tocopherol-O• plus ascorbate (with its available hydrogen) yields semidehydroascorbate (a weak radical) plus tocopherol-OH (Halliway and Gutteridge, 1992). By this process, an aggressive ROI(Reactive Oxygen Intermediate) is eliminated and a weak ROI (dehydroascorbate) is formed, and tocopherol-OH is regenerated. Despite this complex defence system, there are no known endogenous enzymatic antioxidant systems for the hydroxyl radical.

Vitamin E also stimulates the immune response. Some studies have shown lower incidence of infections when vitamin E levels are high, and vitamin E may inhibit cancer initiation through enhanced immunocompetence.

Vitamin E also has a direct chemical function. It inhibits the conversion of nitrites in smoked, pickled and cured foods to nitrosamines in the stomach. Nitrosamines are strong tumour promoters.

Alpha-tocopherol has been shown to be capable of reducing ferric iron to ferrous iron (i.e. to act as a pro-oxidant). Moreover, the ability of alpha-tocopherol to act as a pro-oxidant (reducing agent) or antioxidant depends on whether all of the alpha-tocopherol becomes consumed in the conversion from ferric to ferrous iron or whether, following this interaction, residual alpha-tocopherol is available to scavenge the resultant ROI (Yamamoto and Nike, 1988).

4.1.4 Possible therapeutic effects

 Vitamin E decreases the incidence of ischaemic heart disease (Gey et al. 1991).

 Decreases the incidence of cataract (Packer, 1991; 1992).

 Decreases the incidence of osteoarthritis (Blankenhorn, 1986).

 Decreases the incidence of rheumatoid arthritis (Kheir El-dein et al. 1992).

4.2 Ascorbic acid (vitamin C)

Vitamin C -2D structure C6H8O6

4.2.1 Source and Nature

Ascorbic acid (vitamin C) is a water-soluble, antioxidant present in citrus fruits, potatoes, tomatoes and green leafy vegetables.

Humans are unable to synthesize l-ascorbic acid from d-glucose due to absence of the enzyme L-gulacolactone oxidase (Ensimnger et al.1995). Hence, humans must therefore obtain ascorbic acid from dietary sources.

4.2.2 Mechanism of Action

The chemopreventive action of vitamin C is attributed to two of its functions. It is a water-soluble chain breaking antioxidant (Ishwarial et at 1991). As an antioxidant, it scavenges free radicals and reactive oxygen molecules, which are produced during metabolic pathways of detoxification. It also prevents formation of carcinogens from precursor compounds (Block and Menkes, 1988). The structure of ascorbic acid is reminiscent of glucose, from which it is derived in the majority of mammals.

One important property is its ability to act as a reducing agent (electron donor). Ascorbic acid is a reducing agent with a hydrogen potential of +O.08V, making it capable of reducing such compounds as a molecular oxygen, nitrate and cytochromes a and c. Donation of one electron by ascorbate gives the semi-dehydroascorbate radical (DHA). Ascorbate reacts rapidly with O2•⁻and even more rapidly with •OH to give DHA. DHA, itself can act as a source of vitamin C.

Ascorbic acid + 2O2• + 2H ® H2O2 + DHA

It has also been shown that ascorbate is more potent than a-tocopherol in inhibiting the oxidation of LDL (Low Density Lipoprotein) in a cell free system (Jialal et at 1990). Co-incubation of LDL with ascorbate during similar oxidative condition inhibited LDL oxidation and resulted in preservation of the endogenous antioxidant in the LDL particle (Ishwarial et at, 1991). The concentration of ascorbate used to inhibit LDL oxidation (40-60 mm) is well within the normal plasma range (23-85 pm).

Vitamin C also contributes to the regeneration of membrane bound oxidized vitamin E. It will react with the a -tocopheroxyl radical, resulting in the generation of tocopherol in this process itself being oxidized to dehydroascorbic acid (Ward & Peters 1995). Vitamin C supplementation in animals leads to increased plasma and tissue levels of vitamin E.

In vitro studies suggest that the antioxidant properties of ascorbic acid may not increase linearly as ascorbic acid concentrations rise (Frei et al. 1989). Moreover, ascorbic acid alone can act as a “pro-oxidant” or reducing agent to react with copper or iron salts. Ferric iron (Fe3+) formed by the reaction, Fe2+ + H2O2 ® HO + •OH + Fe3+, is converted by ascorbic acid to ferrous (Fe2+) ion. Ferrous iron is therefore recycled to promote the conversion of more H2O2 to •OH (Halliway et al. 1992).

4.3 Beta Carotene

2-D Structure of Beta Carotene

4.3.1 Source and Nature

Carotenoids are pigmented micronutrients present in fruits and vegetables.

Carotenoids are precursors of vitamin A and have antioxidant effects. While over 600 carotenoids have been found in the food supply, the most common forms are alpha-carotene, beta-carotene, lycopene, crocetin, canthaxanthin, and fucoxanthin. Beta-carotene is the most widely studied. It is composed of two molecules of vitamin A (retinol) joined together. Dietary beta-carotene is converted to retinol at the level of the intestinal mucosa.

4.3.2 Mechanisms of Action

The antioxidant function of beta-carotene is due to its ability to quench singlet oxygen, scavenge free radicals and protect the cell membrane lipids from the harmful effects of oxidative degradation (Krinsky and Deneke, 1982; Santamaria et al. 1991). The quenching involves a physical reaction in which the energy of the excited oxygen is transferred to the carotenoid, forming an excited state molecule (Krinsky, 1993). Quenching of singlet oxygen is the basis for beta-carotene’s well known therapeutic efficacy in erythropoietic protoporphyria (a photosensitivity disorder) (Matthews-Roth, 1993). The ability of beta-carotene and other carotenoids to quench excited oxygen, however, is limited, because the carotenoid itself can be oxidized during the process (autoxidation). Burton and Ingold (Burton and Ingold, 1984) and others have shown that beta-carotene autoxidation in vitro is dose-dependent and dependent upon oxygen concentrations. At higher concentrations, it may function as a pro-oxidant and can activate proteases.

In addition to singlet oxygen, carotenoids are also thought to quench other oxygen free radicals. It is also suggested that beta carotene might react directly with the peroxyl radical at low oxygen tensions; this may provide some synergism to vitamin E which reacts with peroxyl radicals at higher oxygen tensions (Cotgreave et al. 1988).

Carotenoids also have been reported to have a number of other biologic actions, including immuno-enhancement; inhibition of mutagenesis and transformation; and regression of premalignant lesions

5. Antioxidant chemistry of some enzymes

This includes superoxide dismutase, catalase, and peroxidases.

5.1 Superoxide dismutase (SOD)

5.1.1 Source and Nature

SOD is an endogenously produced intracellular enzyme present in essentially every cell in the body.Cellular SOD is actually represented by a group of metalloenzymes with various prosthetic groups.The prevalent enzyme is cupro-zinc (CuZn) SOD, which is a stable dimeric protein (32,000 D). SOD appears in three forms: (1) Cu-Zn SOD in the cytoplasm with two subunits, and (2) Mn-SOD in the mitochondrion (Mayes, 1993; Warner, 1994). A third extracellular SOD recently has been described contains Copper (CuSOD).

2O2• + 2H + SOD ® H2O2 + O2

5.1.2 Mechanism of action

SOD is considered fundamental in the process of eliminating ROI by reducing (adding an electron to) superoxide to form H2O2. Catalase and the selenium-dependent glutathione peroxidase are responsible for reducing H2O2 to H2O.

The respective enzymes that interact with superoxide and H2O2 are tightly regulated through a feedback system. Excessive superoxide inhibits glutathione peroxidase and catalase to modulate the equation from H2O2 to H2O (see Fig.5). Likewise, increased H2O2 slowly inactivates CuZn-SOD. Meanwhile, catalases and glutathione peroxidase, by reducing H2O2, conserve SOD; and SOD, by reducing superoxide, conserves catalases and glutathione peroxidase. Through this feedback system, steady low levels of SOD, glutathione peroxidase, and catalase, as well as superoxide and H2O2 are maintained, which keeps the entire system in a fully functioning state (Fridovich, 1993).

SOD also exhibits antioxidant activity by reducing O2•⁻ that would otherwise lead to the reduction of Fe3+ to Fe2+ and thereby promote •OH formation. When the catalase activity is insufficient to metabolize the H2O2 produced SOD will increase the tissue oxidant activity. Hence, it was found that the antioxidant enzymes function as a tightly balanced system, any disruption of this system would lead to promotion of oxidation .

5.2 The catalase enzyme

This enzyme is a protein enzyme present in most aerobic cells in animal tissues. Catalase is present in all body organs being especially concentrated in the liver & erythrocytes. The brain, heart, skeletal muscle contains only low amounts.

Catalase and glutathione peroxidase seek out hydrogen peroxide and convert it to water and diatomic oxygen. An increase in the production of SOD without a subsequent elevation of catalase or glutathione peroxidase leads to the accumulation of hydrogen peroxide, which gets converted into the hydroxyl radical. Indeed research in the pathogenesis of Down’s syndrome has revealed that the existence of trisomy 21 leads to the overproduction of SOD, the gene for which is located also on chromosome 21. This finding is intriguing in that it reveals the possibility of a genetic link to the increased activity of free radicals. (Krinsky, 1992)

2 H2O2 ® 2 H2O + O2

5.3 Glutathione peroxidase enzyme

The glutathione redox cycle is a central mechanism for reduction of intracellular hydroperoxides.

5.3.1 Source and Nature

It is a tetrameric protein 85,000-D. it has 4 atoms of selenium (Se) bound as seleno-cysteine moieties that confers the catalytic activity. One of the essential requirements is glutathione as a cosubstrate.

Glutathione peroxidase reduces H2O2 to H2O by oxidizing glutathione (GSH) (Equation A). Rereduction of the oxidized form of glutathione (GSSG) is then catalysed by glutathione reductase (Equation B). These enzymes also require trace metal cofactors for maximal efficiency, including selenium for glutathione peroxidase; copper, zinc, or manganese for SOD; and iron for catalase (Halliwell, 1995).

H2O2 + 2 GSH ® GSSG + 2 H2O (equation A)

GSSG + NADPH + H+ ® 2 GSH + NADP+ (equation B)

6. Mode of action of antioxidants

There are four routes:

1.Chain breaking reactions, e.g. alpha-tocopherol which acts in lipid phase to trap “ROD” radical.

2.Reducing the concentration of reactive oxygen species e.g. glutathione.

3.Scavenging initiating radicals e.g. superoxide dismutase which acts in aqueous phase to trap superoxide free radicals.

4.Chelating the transition metal catalysts: A group of compounds serves an antioxidant function by sequestration of transition metals that are well-established pro-oxidants. In this way, transferrin, lactoferrin, and ferritin function to keep iron induced oxidant stress in check and ceruloplasmin and albumin as copper sequestrants.

7. Antioxidant System in our body

The body has developed several endogenous antioxidant systems to deal with the production of ROI. These systems can be divided into enzymatic and nonenzymatic groups.

The enzymatic antioxidants include superoxide dismutase (SOD), which catalyses the conversion of O2•⁻ to H2O2 and H2O; catalase, which then converts H2O2 to H2O and O2; and glutathione peroxidase, which reduces H2O2 to H2O.

The nonenzymatic antioxidants include the lipid-soluble vitamins, vitamin E and vitamin A or provitamin A (beta-carotene), and the water-soluble vitamin C and GSH. Vitamin E has been described as the major chain-breaking antioxidant in humans (Packer, 1992). Because of its lipid solubility, vitamin E is located within cell membranes, where it interrupts lipid peroxidation and may play a role in modulating intracellular signalling pathways that rely on ROI (Kagan et al. 1990; Azzi et al. 1993). Vitamin E can also directly quench ROI, including O2•, •OH, and (Algayer et al. 1992) O2.

8. Commercial Sources of Natural Antioxidants

The most common natural antioxidant preparations in the market are mixed tocopherols, which are by-products of vegetable oil refining. In addition, spices or their oleoresins and extracts, such as those of rosemary and sage, green tea extracts, other plant-based mixtures, such as those of mustard and certain unsaponifiables of edible oils, and, of course, carotenoids are also important (Table 2) ( Ho et al., 1994; Shahidi, 1997).

9. Efficacy of anti oxidants in different systems

The chemical composition and structures of active extract components are important factors governing the efficacy of natural antioxidants in different foods. Thus, phenolic compounds with ortho- and para- dihydroxylation or a hydroxy and a methoxy group are more effective than simple phenolics. In addition, phenylpropanoids with extended conjugation are more effective than benzoic acid derivatives. Furthermore, hydrophilicity and lipophilicity of the active components is dictated by the appropriateness of antioxidants in systems. In general, more hydrophilic antioxidants are better in stabilizing bulk oil than oil-in-water emulsions while the activity of lipophilic antioxidants follows the opposite trend. There are also many other factors that must be taken into account when considering and selecting antioxidants and extracts for food application. Specifically, attention should be paid to the photosensitizing effect of chlorophylls in natural extracts. In addition, the level of incorporation of antioxidants in foods should be optimized and the use of chelating agents considered, when and where appropriate. Many antioxidants behave prooxidatively at high concentrations or when present together with ions of transition metals; such effects are also important when considering the in-vivo activity of antioxidants ( Shahidi and Ho, 2000). Some chelators, such as polyphosphates, in addition to metal sequestration, may also exert other beneficial effects such as to improve the cooking yield and juiciness of meat and poultry products or keeping quality of fresh seafoods. The role of natural antioxidants in foods is expected to rise over the years to come.

10. Summary

Antioxidant are molecules that can safely interact with the free radicals and terminate the chain reactions before the vital molecules are damaged.Although there are several enzyme system and vitamins that scavenges free radicals the principle antioxidant in the body are Vitamin E, Vitamin C,beta carotene, catalase enzyme, super oxide dismutase enzyme,glutathion peroxidase enzyme etc.Vitamin E ,a lipid soluble antioxidant prevent peroxidation of phospholipid.Vitamin C is a water soluble chain breaking antioxidant. Beta carotene protect cell membrane lipid from harmful effect of antioxidant damage.Catalase ,glutathion peroxidase ,super oxide dismutase etc. enzyme systems also prevent our body oxidative damage by free radicals.

11. Conclusion

Antioxidant plays an important role to prevent cancer,and other disease.They also have role in slowing ageing process and preventing heart disease.So antioxidant are very much necessary for our body .But our body can’t manufacture these chemicals ,so they must be supplied through diet.Although there is a little doubt that antioxidant are necessary component for good health , no one knows if supplements should be taken or not and if so how much is optimum.Though antioxidant supplement were thought to be harmless but as we are becoming more aware of this chemicals we come to know that antioxidant may be harmful for our body in some cases.In normal concentration vitamin C and beta carotene are antioxidant but at higher concentration they are pro oxidant and thus harmful .Also very little is known about the long term consequences of megadoses of antioxidant .the body’s finely tuned mechanism are carefully balanced to withstand a variety of insults.Taking chemicals without understanding of all their effect may disrupt this balance. So we should follow the following recommendations.

1. It will be helpful for us to follow a balanced training program that emphasizes regular exercise and to eat 5 servings of fruit or vegetables per day. This will ensure that we are developing our inherent antioxidant systems and that our diet is providing the necessary components.

2. Weekend warriors should strongly consider a more balanced approach to exercise. Failing that, consider supplementation.

3. For extremely demanding races (such as an ultra distance event ), or when adapting to high altitude, it will be helpful to take a vitamin E supplement @ 100 to 200 IU per day for several weeks up to and following the race.

4. We should look for upcoming FDA recommendations, but we should be wary of advertising and media hype.

5. We should not over supplement.

12. Future Scope of Research

Antioxidant are necessary for our health but we do not know the exact dose and the way how to supplement it. So further research are required to know more about antioxidant. There are so many flora and fauna in our environment which may contain antioxidant chemicals. So there is a huge scope to conduct research work in this interesting topic to know

1) How much antioxidant supplementation is required.

2) Natural sources of different antioxidant.

3) To discover antioxidant property of different chemicals.

4) To know whether they have any other pharmacological and toxicological effect.

IC asked:


The following good habits are actually shared by most dermatologists as their best advices for a clear complexion.

Good Habit #1: Avoid Too Much Cosmeceuticals

Numerous experts have said that with more and more beauty potions with alpha-hydroxy acids (AHAs), antioxidants, salicylic acids, and retinoids in them, blending a cleanser from one line with a scrub or daytime moisturizer from another, then a night cream from yet another can lead to over-exfoliation as well as irritation. This can no doubt add up to a real dilemma, especially for those women who have olive and darker complexions. This is also possible for women who are more prone to discoloration when their skin is irritated.

So, to play it really safe, it is important that you only stick with one line of products. But, only use the line of products which are formulated to work together. It is often said that if for instance you use any prescription products like the famous Renova, the advice of your dermatologist is highly needed. Ask your specialist regarding on how to mix prescription treatments with the over the counter cosmeceutical products. Just don’t overdo beauty products.

Good Habit #2: Consider a Healthy Exercise

Exercise is great for a beautiful skin. So, considering at least twenty to thirty minutes of any aerobic exercise is worth trying. It will give you a glow, as it is often said. One of the supports for this is the fact that exercise boosts blood flow. It is this increased blood flow which will bring more nutrients to the skin. However, it is important to be aware that the accumulation of sebum or oil through perspiration can result in sweatband acne, folliculitis, as well as spiky heat. But, don’t worry; there is a simple solution for this – shower as soon as possible after shaking your booty.

Good Habit #3: Intimate with the Phone? Don’t Be!

Always note that constant rubbing on the mouthpiece may lead to rashes around the chin and mouth. This is what many people have believed, including dermatologists. So, it is important that when talking to somebody on the phone, hold the phone away from those mentioned areas when talking. Also, clean the phone often with a mild soapy solution or perhaps rubbing alcohol.

Good Habit #4: Examine Your Birthday Suit for Spots

When it comes to skin care, any sudden or suspicious-looking mole, bump or other growth on the skin is a reason to see a dermatologist. Nevertheless, as skin cancer rates skyrocketed, having a full body check up by a professional is very crucial. This is especially true for those us living in the baby-oil-and-iodine, pre-sunscreen generation.

Also, it is said that those who belong in a high risk group, meaning having a personal or family history of skin cancer, a lot of moles, fair skin, or light eyes or hair, should consult a specialist for a regular check up. The regular examination should start in their teens and probably no later than age 35. However, even if you do not belong in a high risk group, it is still recommended that between the ages of 20 and 40, people must have a cancer-related check up. The check up must include skin exam and must be considered every three to four years. Once you hit your 40s, start undergoing a cancer-related examination with skin exam every year. Aside from that, it is advisable that you do monthly self-exams in order for you to keep an eye out for changes and growths.

Good Habit #5: Eat Healthy Foods

Healthy foods refer to those that help your skin and body fight against the bad forces outside and inside. You must consider antioxidants such as vitamin A, C and E as they are highly potent for sun damage and fight certain cancers, including skin cancer. This is actually the reason that makes antioxidants essential to your health. Along with this, a well balanced diet is highly recommended. This means making yourself comfortable with a diet filled with at least five servings a day of fruits and vegetables, plus a multivitamin that meets the RDA standards.

Cdmohatta asked:


Anti-aging and skin care products added with AHA are flooding the market. Alpha hydroxy acids are supposed to smoothen fine lines and surface wrinkles, improve skin texture and tone, unblock and cleanse pores. They also improve oily skin or acne, and improve skin condition in general. AHA or Alpha Hydroxy Acids are not new to skin care. Legends of Cleopatras milk baths are well known in beauty and skin care. Polynesians used sugarcane and fruit juices to soften their skin. The factor common to the properties of these natural products is this group of natural substances found in sugarcane, fruits, milk, molasses, etc., called AHA.

What are AHA molecules?

To find out if a cosmetic contains an AHA, look on the list of ingredients. AHA ingredients may be listed as:

Glycolic acid, lactic acid, malic acid, citric acid, glycolic acid + ammonium glycolate, alpha-hydroxyethanoic acid + ammonium alpha-hydroxyethanoate, alpha-hydroxyoctanoic acid, alpha-hydroxycaprylic acid, hydroxycaprylic acid, mixed fruit acid, tri-alpha hydroxy fruit acids, triple fruit acid, sugar cane extract, alpha hydroxy and botanical complex, L-alpha hydroxy acid glycomer in cross linked fatty acids alpha nutrium (three AHAs).

How AHA works?

To find out how AHA works for skin care, let us see how the skin grows old, and how to keep it younger. Cells in the outer layers of skin are bound together by inter-cellular fluid. As one ages, this glue-like substance binds the skin cells tighter and denser. Dead skin layers build up and unlike young skin, natural exfoliation becomes difficult. This group of natural acids has the ability to loosen this inter-cellular fluid, and allows the top layer of dead skin to slough off easily. Thus AHA products cause exfoliation, or shedding of the surface skin. The extent of exfoliation depends on the type and concentration of the AHA, its pH (acidity), and other ingredients in the product. Most skin care cosmetics sold to consumers contain AHA at levels up to 10 percent.

Side effects of AHA

The side effects from AHA containing products can include burns, itching, pain, and possibly scarring. The degree of acidity (the pH) of the product also can affect irritation. Some experts advise that people should purchase products with AHA concentrations of 10% or less and a pH of 3.5 or higher (the higher the pH, the lower the acidity). If any adverse effects occur, the use should be stopped immediately. In any case, people are advised to avoid sunlight or use proper protection when using them.

The best way to use AHA products would be to try the product for some time and see the difference in skin. Avoid sunlight exposure while using AHA products and watch for any side effects. Consulting your dermatologist before using these products would be a still better course of action, and the best would be to take Cleopatras recipe for Milk bath, and remain younger.

This article is only for informative purposes. This article is not intended to be a medical advise and it is not a substitute for professional medical advice. Please consult your doctor for your medical concerns. Please follow any tip given in this article only after consulting your doctor. The author is not liable for any outcome or damage resulting from information obtained from this article.

zoebeans asked:


Why does amino groups get acylated with acetic anhydride but not the hydroxy group? Thank you!
Sorry forgot to say this is in paracetamol. Why does the hydroxy gruop get acylated in aspirin but not paracetamol?

Kurt Huff asked:


Power for your vehicles can be helped by hydrogen. It will double your MPG (miles per gallon), which in essence is getting you half price gas costs. Hydrogen has been the power source of the sun for eons. When volcanoes flare it is from hydrogen gas. The space shuttle is launched using hydrogen. Hydrogen, the most prevalent element in the universe, can now be used in your vehicles.

HOW IT WORKS:

A water molecule is made up of two hydrogen atoms with one oxygen atom. Electrolysis, the applying of electricity to water, breaks the molecular bonds thus changing H2O (water) to H O H (a gas known as Hydroxy or Browns Gas). This happens in a fuel cell, also called a hybrid energy unit. Browns gas vapor is manufactured on demand, by an electrolyzer. It is then directed into the air intake of your engine. When mixed with the air/gasoline or air/diesel, hydroxy gas acts as a catalyst enhancing the combustion process which improves the engines power output.

THE BENEFICIAL EFFECTS:

SAVES YOU MONEY:

You get much better fuel use. You will save hundreds to thousands of dollars annually on each vehicles fuel costs (for about a penny a day to operate)!

Engines run cleaner and last longer with fewer carbon deposits. This means less down time and lower maintenance expenses.

You get less pollution. Emissions testing is easier to pass.

IMPROVES YOUR VEHICLES PERFORMANCE:

Increases power for greater acceleration. Also stronger towing and faster uphill climbs. Calmer, quieter and much smoother engine operation from an improved combustion cycle.

HELPS EARTH:

Reduces reliance on fossil fuels. Lowers operating temperature of the engine, reducing global warming. This helpful process actually adds more oxygen into the air we breathe.

Using water as fuel has these great benefits, but it is not always cheap. A professional hybrid conversion could cost over $2,000. Self installed kits are up to $500.

Happily, several low cost conversion-kit guides have shown up recently. These show how to convert your car to an efficient hybrid yourself with little or no technical knowledge, and inexpensive materials. A group of analysts from All CB Reviews checked out these new guides.

THE CONCLUSIONS:

Eleven water fuel hybrid kits were reviewed, but only one met all criteria:

* Fuel Savings - at least 50% savings of fuel

* Fast and Easy Setup - in only a few hours, even for newbies

* Lowest Price Set Up - under $50!

And their recommendation is . . . Run Your Car On Water, see http://www.runyourcarwithwater.com/?hop=yeshua4u

With the proven increase of gas mileage, this product can pay for itself in less than a week. This kit works with gas or diesel cars, vans, trucks, boats, RVs and SUVs.

The first runner up was http://water4gas.com/2books.htm?hop=yeshua4u Water4Gas has an extensive amount of information about free energy. It also has an extremely useful section for big rig semi tractor trailer truckers.

And the second runner up was http://www.fueltrips.com/?hop=yeshua4u

Fuel trips has an extra section on fuel saving tips. It also has a good section on how to make your own bio diesel.

These kits positively do work! They have 60 day money back guarantees and they will save you lots of money.

Mark Henry asked:


Active Life: 4-6 hours

Drug Class: Anabolic/Androgenic Steroid (Oral)

Average Dose: Men 50-150 mg/day……Women 50-75 mg/day

Acne: Rare

Water Retention: No

High Blood Pressure: Rare

Liver Toxic: Very low and only in very high dosages

Aromatization: None

DHT Conversion: No

Decrease HPTA function: Low

Comments: Moderately Anabolic/Low Androgenic

Primobolan is an almost pure anabolic with an extremely low androgenic component. The ratio of the anabolic to the androgenic effect is indeed very favorable but, since the overall anabolic effect is only moderately strong, Primobolan tablets have only a limited effect in building up muscle mass and strength. With Primobolan neither fast weight gains nor explosive strength gains occur. Primobolan is therefore mostly taken over a prolonged period since it gives only a slow but also a high-quality muscle gain which mostly remains after use of the compound is discontinued.

An effective daily dose observed in athletes is in the range of 50- 150 mg so that the 25 mg tablets are preferred to the 5 mg tablets. As for the recommended dose, the athlete obtains interesting information from the German package insert by Schering AG for their compound Primobolan S: “Unless otherwise prescribed the following guidelines apply: The dosage should be I - 1,5 mg per pound of body weight/day, that is 4-6 tablets for 100 pound of bodyweight.” A bodybuilder weighing 100 kg should therefore take 200-300 mg daily which would corre-spond to a dosage of eight to twelve 25 mg tablets per day. We believe that this dosage is too high; however, this example shows that a fairly large dosage of the oral acetate form is necessary. The reason is that the Primobolan acetate tablets are not I 7-alpha alky-lated and, during the first pass in the liver, a large part of the substance is destroyed and thus deactivated leaving only a much smaller quantity of the substance to get into the blood.

If Primobolan is the only steroid that is taken, then with respect to strength and muscle buildup, it will usually lead to success in women and steroid novices. This, however, changes greatly when Primobolan is combined with steroids that are moderately too highly androgenic but which themselves do not aromatize or retain water. In such an environment the anabolic effect of Primobolan can develop to its optimum. Masteron, Parabolan, Equipoise, and Winstrol, are par-ticularly suitable. The effect can be optimized by the additional in-take of Oxandrolone. Steroid novices and the less advanced achieve a good strength and muscle gain by taking 50- 100 mg Primobolan S/day and 150 mg Winstrol Depot/week, without retaining water. Even competing athletes report good quality gains with continu-ously “harder” muscles when taking 150 mg Primobolan S/day and 50 mg Winstrol Depot every two days, as well as 76 mg of Parabolan every two days.

The main uses of the Primobolan tablets, however, are in the preparation for a competition and in use by women. Since the acetate form does not aromatize into estrogens and does not cause water retention, the use of Primobolan during competitions is widespread. Acetate tablets are special in that they actively help burn fat. The Primobolan acetate tablets, however, must never be taken as the only steroid during a diet since, due to its extremely low androgenic effect, significant losses in muscle and strength can occur and there is a risk of overtraining. The above mentioned common steroid combinations are extremely effective when combined with a suitable diet during the preparation for a competition. Due to the fact that the acetate tablets burn fat but, at the same time, that in large part they are already deactivated in the liver, it would be most efficient to apply the compound locally, bringing the substance directly into the blood through the skin in the areas with undesired fat deposits. At first this seems a little adventurous, but it is possible with the DMSO compound. Dimethyl sulfoxide (DMSO) is one of few substances which are fully absorbed through the skin and distributed through the body It is included in many ointments and gels which are used to treat sport injuries, contusions, swellings, and effusions in order to transport the casing substance through the skin. ln addi-tion, DMSO makes the skin permeable to other substances.

Finely grind up one 25 mg Primobolan tablet with the grip of a knife on your kitchen board, mix it with half a teaspoon of DMSO gel and then apply a thin layer to your skin. It is important that you only apply it; do not rub it in. One or two applications is usu-ally enough. Another way to avoid the liver and consequent destruction of the substance is to grind up the Primobolan tablets in a mortar and consume them together with heated vitamin E oil. The Primobolan/vitamin E mixture reaches the blood similar to Andriol that is the absorption occurs through the lymph system and the solution does not reach the liver through the portal vessel. Since the Primobolan tablets are not I 7-alpha alkylated but have a I 7-beta hydroxy group they are almost non-toxic to the liver. in a high dosage, however, they can influence the liver values resulting in higher biliburin, GPT, GOT, and alkaline phosphatase. Primobolan generally does not cause any significant side effects since it does not aromatize, does not cause water retention, is not I 7-alpha alkylated, and is only slightly androgenic. Blood pressure, liver values, cholesterol level, HDL and LDL values usually remain unaffected, making Primobolan well-liked by health-conscious older athletes. Primo is often an “entry drug” for novice users and, due to its rare side effects, encourages many steroid users to switch to “harder” stuff such as Dianabol, Anadrol 50, and testosterone. Since Primobolan is a precursor of dihydrotestosterone it can accelerate hair loss if such a predisposition exists.

The availability of Primobolan Acetate tablets on the black market is quite poor both in Europe and the U.S. The price for one 25 mg tablet on the black market is about $2.

Trade Names:

Primobolan (o.c.) 5 mg tab.; Schering G, A, B

Primobolan 5 mg tab.; Schering Mexico, Costa Rica, Dom. Rep., Ecuador, E

Primobolan S 25 mg tab.; Schering G, NL; Leiras FI; Berlimed South Africa

Primobolan (o.c.) 50 mg tab.; Schering FR

Kurt Huff asked:


Power for your vehicles can be helped by hydrogen. It will double your MPG (miles per gallon), which in essence is getting you half price gas costs. Hydrogen has been the power source of the sun for eons. When volcanoes flare it is from hydrogen gas. The space shuttle is launched using hydrogen. Hydrogen, the most prevalent element in the universe, can now be used in your vehicles.

HOW IT WORKS:

A water molecule is made up of two hydrogen atoms with one oxygen atom. Electrolysis, the applying of electricity to water, breaks the molecular bonds thus changing H2O (water) to H O H (a gas known as Hydroxy or Browns Gas). This happens in a fuel cell, also called a hybrid energy unit. Browns gas vapor is manufactured on demand, by an electrolyzer. It is then directed into the air intake of your engine. When mixed with the air/gasoline or air/diesel, hydroxy gas acts as a catalyst enhancing the combustion process which improves the engines power output.

THE BENEFICIAL EFFECTS:

SAVES YOU MONEY:

You get much better fuel use. You will save hundreds to thousands of dollars annually on each vehicles fuel costs (for about a penny a day to operate)!

Engines run cleaner and last longer with fewer carbon deposits. This means less down time and lower maintenance expenses.

You get less pollution. Emissions testing is easier to pass.

IMPROVES YOUR VEHICLES PERFORMANCE:

Increases power for greater acceleration. Also stronger towing and faster uphill climbs. Calmer, quieter and much smoother engine operation from an improved combustion cycle.

HELPS EARTH:

Reduces reliance on fossil fuels. Lowers operating temperature of the engine, reducing global warming. This helpful process actually adds more oxygen into the air we breathe.

Using water as fuel has these great benefits, but it is not always cheap. A professional hybrid conversion could cost over $2,000. Self installed kits are up to $500.

Happily, several low cost conversion-kit guides have shown up recently. These show how to convert your car to an efficient hybrid yourself with little or no technical knowledge, and inexpensive materials. A group of analysts from All CB Reviews checked out these new guides.

THE CONCLUSIONS:

Eleven water fuel hybrid kits were reviewed, but only one met all criteria:

* Fuel Savings - at least 50% savings of fuel

* Fast and Easy Setup - in only a few hours, even for newbies

* Lowest Price Set Up - under $50!

And their recommendation is . . . Run Your Car On Water, see http://www.runyourcarwithwater.com/?hop=yeshua4u

With the proven increase of gas mileage, this product can pay for itself in less than a week. This kit works with gas or diesel cars, vans, trucks, boats, RVs and SUVs.

The first runner up was http://water4gas.com/2books.htm?hop=yeshua4u Water4Gas has an extensive amount of information about free energy. It also has an extremely useful section for big rig semi tractor trailer truckers.

And the second runner up was http://www.fueltrips.com/?hop=yeshua4u

Fuel trips has an extra section on fuel saving tips. It also has a good section on how to make your own bio diesel.

These kits positively do work! They have 60 day money back guarantees and they will save you lots of money.

Dr. Randy Wysong asked:


FATTY ACIDS

Fatty acids are long-chain “carboxylic” acids, that is, hydrocarbon (alkyl) chains containing the terminal -COOH chemical group. (Fig. 2)

[ Fatty Acid Structure Image ]

http://www.wysong.net/articles/lipid/figures/figure2.jpg

Fatty acids contain from 4 to 22 carbon atoms. They can be saturated, having no double bonds in the carbon chain, mono-unsaturated with one double bond in the chain, or polyunsaturated with several double bonds in the fatty acid.

In nature, triglycerides occur linked (esterified) to glycerol and hence are called glycerides. If solid they are called fats, if liquid they are called oils. One fatty acid combined (esterified) with glycerol is a monoglyceride, two combined is a diglyceride, and three attached to the glycerol backbone (the most possible) is a triglyceride.

Saturated fat (e.g. palmitic and stearic) exclusively fit in the 1 and 3 positions whereas unsaturated fatty acids can distribute randomly among the three positions on the glycerol backbone. A common configuration is thus a saturated fat in positions 1 and 3 and an unsaturated fatty acid in position 2. (Fig. 3)

[ Structure of a Triglyceride Image ]

http://www.wysong.net/articles/lipid/figures//figure3.jpg

Fatty acids containing fewer than 16 carbon atoms, and saturated fatty acids, are largely oxidized to provide energy. Those containing 16 to 22 carbon atoms can also be oxidized for energy, but in addition can be incorporated into cell membranes, regulate metabolism after conversion to eicosanoids (prostaglandins, thromboxanes, leukotrienes, lipoxins, and various other hydroxy analogs discussed later) changed to other fatty acids, or stored in fat (adipose) tissues.

NOMENCLATURE

Abbreviated notations simplify fatty acid nomenclature. In the case of linoleic acid (abbreviated LA; notation 18:2w6). The 18 means the molecule has 18 carbon atoms, the 2 means that there are two double bonds in the molecule and the w6 means the first double bond begins with the sixth carbon atom counting from the methyl (CH3), omega (w) end of the carbon chain. (In many publications omega is designated as a small case “n” instead of” w.”) The other end of the chain, the carboxylic acid end, is termed the delta (?) end. (Fig. 4)

[ Linoleic and Linolenic Acid Structure and Nomenclature Image ]

http://www.wysong.net/articles/lipid/figures/figure4.jpg

The double bonds in the nutritionally important fatty acids are separated by methylene groups (CH2). Hence, the second double bond in LA must begin with the ninth carbon atom. Common fatty acids are detailed in Figure 5.

[Nomenclature and Structure of Common Fatty Acids Image ]

http://www.wysong.net/articles/lipid/figures/figure5.jpg

PHOSPHOLIPIDS

Fatty acids with 16 and l8-carbon chains can participate in the manufacture of phospholipids which are the main structural components of cell membranes. Phospholipids are similar to triglycerides in that fatty acid molecules are attached to a glycerol molecule, a three carbon alcohol (or, less commonly, sphingosine, a more complex amino alcohol). In triglycerides, all three esterifiable positions on a glycerol molecule are occupied by a fatty acid. In a phospholipids, only two are so occupied and the third is esterified to phosphoric acid which may have in turn other compounds attached to it such as choline, serine, glycerol, inositol or ethanolamine. Lecithin, the best known phospholipids, has choline attached to the phosphate and is thus termed phosphatidylcholine. If phosphoric acid alone is attached, the compound is called a phosphotidate. Many molecular variations are also possible by mixing various fatty acids on the glycerol backbone. (Fig. 6)

[Structure of Phospholipids Image ]

http://www.wysong.net/articles/lipid/figures/figure6.jpg

ISOMERS

Figure 7 demonstrates the biochemically important cis- and trans- forms of fatty acids. Notice in the cis- form the hydrogen atoms on the carbons adjacent to the double bond are on the same side of the molecule.

The repulsive forces between these “crowded” hydrogen atoms cause unsaturated fatty acids to assume particular non-linear shapes which play an important role in lipid membrane configuration, fluidity, and in biochemical reactions involving enzymes.

[ Isomers Image ]

http://www.wysong.net/articles/lipid/figures/figure7.jpg

[ Fatty Acid Configurations Image ]

http://www.wysong.net/articles/lipid/figures/figure8.jpg

In the trans- form of fatty acids, the hydrogen atoms are on opposite sides of the molecule and their repulsive forces cancel each other, and thus the molecule is not bent. Although the trans- form is more stable, its chemical properties and biological functions are altered. (Figs. 7 and

BIOLOGICAL MEMBRANES

A biological (plasma) membrane surrounds all cells within tissue as well as the organelles lying within the cytoplasm. To help visualize size, if we were the size of bacteria, a cell would be the size of a large auditorium. (In true size, one billion cells fit in one cubic inch.) This cell “auditorium” is housed by a skin only two molecules thick. The various drawings of biochemicals depicted in these pages would therefore be as they would appear from our size as a bacteria, or as a bacteria sized person would see them through a magnifying glass.

The membrane is not a static sac, but rather a complex of chemicals with gates and pumps to control chemical and ionic balances, receptors for stimuli and signal generators. It is made up primarily of phospholipids, protein, glycolipids and cholesterol, all of which of course come directly from food or are synthesized in situ by components of food after they have been broken down by digestion.

Membrane lipids are amphipathic in that they contain both a hydrophilic polar end and a hydrophobic non-polar end. Phospholipids orient themselves into a bilayer sheet in membranes with the hydrophilic ends pointed to the outside and the hydrophobic hydrocarbon tails pointing to the inside. These properties make salts of fatty acids an important functional component of soaps since their fat soluble hydrophobic ends attract “fatty dirt” and their water soluble hydrophilic ends can attract “watery dirt.”

The neck of a fatty acid is located next to the delta carboxyl end and is stiff. The tail portion next to the omega end, if containing cis- double bonds, is highly active, oscillating at a million vibrations per second. (Figs. 8 and 9)

[ Membrane Image ]

http://www.wysong.net/articles/lipid/figures/figure8a.jpg

[Triglyceride Fluidity ]

http://www.wysong.net/articles/lipid/figures/figure9.jpg

Lipids, and some proteins within membranes, are also in constant lateral motion. In a bacterium, a single phospholipid will travel from one end to the other in one second. Thus membranes are in effect two-dimensional solutions of an array of oriented molecules.

Although membranes are considered lipid bilayers, almost 50% of the membrane is composed of protein which serves many functional roles. The sugar residues of glycolipids (sphingosine + fatty acid + sugar, such as sphingomyelin) and glycoproteins (sugars attached to membrane proteins) are found protruding on the outer surface of membranes. Cholesterol, as well as the length of fatty acid tails and their degree of saturation, affects membrane fluidity. Cholesterol sandwiched between membrane fatty acids prevents their crystallization. (Fig. 10)

[ Bilipid Cell Membrane Image ]

http://www.wysong.net/articles/lipid/figures/figure10.jpg

The specific spatial configuration and electronegative discontinuity of essential fatty acids pennit linkage with sulfhydral protein groups in membranes to form pi electron quantum mechanical membrane potentials that affect the transport of oxygen into tissues. Also, it is on the lipid membranes of mitochondria that cellular respiration occurs and energy is packaged for use throughout the body. Thus dietary fatty acids, which ultimately build all membranes, affect the burning of nutrient fuels — the most fundamental of life’s energetic properties.

Classic artistic renderings of biological membranes are overly simplistic and create an impression of static barriers. Similarly a photograph of a rocket ship streaking toward space says nothing about its actual movement, speed or the hubbub of activity occurring inside of it.

The real biological membrane, containing millions of fatty acid tails vibrating at millions of times per second, with deletions and substitutions in constant progress and biochemical doors opening and closing selectively permitting the passage of food and waste, is a dynamic, an action more than a structure and literally beyond comprehension. It can be described with words, like infinity can be, but not rationally fully grasped.

When one considers that fatty acids comprise the membrane structure of all cells and their enclosed organelles, the breadth of their importance begins to emerge. Membrane fatty acids are indeed the gatekeepers of life.

The dynamic and complex: aspects of fatty acid chemistry help us to understand nutrition at a more meaningful level. Percent fat on a food label is valueless in determining the healthiness of a product. Are the fats saturated or unsaturated? If unsaturated, what are the ratios of omega 9’s to 6’s to 3’s? Have the fats been hydrogenated? If so, what are the levels of potentially toxic trans-isomers? Are the lipids oxidized or complexed with other nutrients such as protein? Does the product contain the nutrients which were associated with the lipid in its natural context, such as antioxidants, certain vitamins, and minerals? What is the stability when subject to time, heat, light and air?

References available within book text, click the following link to view this article on wysong.net:

http://www.wysong.net/articles/lipid/02_article_lipid_chapter_two_lipid_biochemistry.shtml

For further reading, or for more information about, Dr Wysong and the Wysong Corporation please visit www.wysong.net or write to wysong@wysong.net. For resources on healthier foods for people including snacks, and breakfast cereals please visit www.cerealwysong.com.

Tonnie asked:


a) carboxyl
b) carbonyl
c) hydroxy
d) amide