Peroxide-induced conformational transitions of peanut storage protein (arachin)

Several effects of peroxides on protein have been described in the literature. Some of the effects have been ascribed to alterations in protein conformation but this has never been examined directly. This paper described responses of peanut storage globulin (arachin) to rancid oil and hydrogen peroxide as measured by electrophoretic mobility, antigenicity and circular dichroism of the globulin. Rancid oil and 3% hydrogen peroxide had little effect on these properties but 30% hydrogen peroxide increased the mobility, abolished the antigenicity and reduced the ordered structural modes of the protein. The results indicated that changes in protein conformation do not occur after contact with organoleptically rancid oil or dilute peroxides but do occur with concentrated peroxides.     

Superoxide-dependent lipid peroxidation. Problems with the use of catalase as a specific probe for fenton-derived hydroxyl radicals

Hydroxyl radicals (OH.) can initiate lipid oxidation by hydrogen abstraction. Transition metals however, particularly iron and copper, stimulate lipid oxidation by reacting with lipid peroxides to form new radical species. The haem-iron protein catalase can react non-specifically with lipid peroxides in this way resulting in loss of their conjugated diene structures. When a superoxide-generating system is used to stimulate lipid autoxidation, catalase can conceivably inhibit the reaction in two ways (A) by decomposing lipid peroxides as they are formed (B) through the removal of hydrogen peroxide preventing OH. radical formation. Results presented here suggest that the latter interpretation, although commonly presented, cannot be automatically assumed.     

The reaction of horseradish peroxidase with hydroperoxides derived from Triton X-100

All of the commercially available Triton X-100 examined gave Compound I upon reaction with horseradish peroxidase, followed by its gradual transition into Compound II. Titration of horseradish peroxidase with Triton X-100 to form Compound I indicated that 1% (v/v) aqueous solutions of the detergent contained 0.4 to 3.2 microM equivalent peroxide but iodometric titration revealed 1.1 to 5.0 microM peroxide, suggesting the occurrence of different types of peroxides, reactive and unreactive with the peroxidase. The rate constant for Compound I formation was 1.5 X 10(7) M-1 S-1 at pH 7.4 at 25 degrees C, and for conversion into Compound II apparent first-order rate constants were 5.2 X 10(-3) to 1.7 X 10(-2) S-1. These results indicate that the Triton peroxides are as highly reactive as hydrogen peroxide. The amount of Triton peroxides increased as aqueous solutions of the detergent were allowed to stand, but the peroxides were destroyed by treatment with sodium borohydride. Although freshly prepared aqueous solutions of sodium cholate, sodium dodecyl sulfate, Tween 20 (polyoxyethylene sorbitan monolaurate), and Emasol 1130 (an equivalent of Tween 20) did not contain any detectable amount of peroxide, aged solutions of sodium dodecyl sulfate and Emasol 1130 contained peroxides. These observations suggest the need for appropriate precautions when biologically active substances vulnerable to attack by peroxides are incubated with Triton X-100 either for their solubilization from biomembranes or for other processing.     

活性氧对苏云金芽孢杆菌伴孢晶体的损伤作用

用SDSPAGE电泳分析和生物测定方法研究了过氧化氢(H2O2)和羟自由基(·OH)对苏云金芽孢杆菌(Bacillus thuringiensis)伴孢晶体的损伤作用。结果表明,这两种活性氧对伴孢晶体均有一定程度的损伤作用,这种损伤作用与活性氧的浓度成正相关,并且·OH对伴孢晶体的损伤作用明显强于H2O2。     

The effectiveness of a lipid peroxide in oxidizing protein and non-protein thiols

1. Thiol oxidation by a lipid peroxide or hydrogen peroxide was as efficient in denatured non-haem proteins as in small thiols. Both peroxides were relatively ineffective in oxidizing haemoprotein thiols, especially at low pH. Increased amounts of haematin decreased greatly the efficiency of GSH oxidation by peroxides especially at low pH. 2. Other than the haematin ring, the thiol group was found to be probably the group in proteins most sensitive to modification by peroxides. 3. At low concentrations, the fatty acid moiety of a lipid peroxide appeared to impede thiol oxidation in proteins, probably by hydrophobic bonding to the protein, rather than to stimulate thiol oxidation by denaturing the protein and thereby increasing the exposure and reactivity of the thiol group. 4. The relative rates of thiol oxidation by peroxides in the different thiols were: haemoprotein thiols>small thiols>other protein thiols. In all cases, thiol oxidation was much more rapid by the lipid peroxide than by hydrogen peroxide.     

Limited utilization of exogenous arachidonic acid by the prostaglandin cyclooxygenase in gastric mucosa: the role of protein binding, glutathione peroxidase, and hydrogen peroxides.

We investigated the utilization of exogenous 14C-labelled arachidonic acid by the cyclooxygenase system of the gastric mucosa and its alteration by cytosolic factors, protein binding, glutathione peroxidase (GSH-Px), and hydrogen peroxides. Total prostaglandin (PG) synthesis from gastric microsomes was reduced in a dose- dependent manner to 12% and 68% of controls by increasing amounts of the 105,000g supernatant or albumin (8mg protein/ml), respectively (p less than 0.01). The inhibitory cytosolic factor was heat labile, protease sensitive, and was retained by a 300,000 Dalton ultrafiltration membrane. Thus, it was likely a protein. Other possible inhibitory mechanisms like protease- or heme-induced destabilization of the cyclooxygenase, haptoglobin-mediated inhibition, or self-inactivation by endogenous substrate were excluded. N-ethylmaleimide (NEM), an agent that alkylates sulfhydryl-groups thereby inhibiting GSH-Px, abolished the inhibitory effect of cytosol in a dose-dependent fashion. In contrast to their inhibition of prostaglandin synthesis, the binding of arachidonic acid by albumin or cytosolic proteins accounted to 75% and 19% under comparable conditions, respectively, however, cytosolic fatty acid binding was unaffected by NEM. Thus, it was concluded that the inhibitory effect of cytosol, in contrast to albumin, was mediated by a sulfhydryl-depending process, probably a GSH-Px. This conclusion was supported by a qualitatively comparable inhibition by a purified GSH-Px from bovine erythrocytes. The inhibitory action of cytosolic proteins was reduced significantly by increasing concentrations or repeated application of arachidonic acid; therefore, cytosolic GSH-Px was likely to affect substrate utilization by the microsomal PGH synthase through reduction of activating substrate peroxides. Similarly, the in vitro formation of cyclooxygenase products by mucosal homogenate or gastric microsomes in the absence of cytosol was limited at substrate concentrations below 80 microM, despite sufficient nonesterified arachidonic acid remaining in the incubate. This limitation was mediated only partially by self-inactivation of the prostaglandin cyclooxygenase. Neither N-ethylmaleimide nor repeated application of hydrogen peroxides increased substrate utilization by isolated microsomes, excluding contamination by GSH-Px or simply a lack of hydrogen peroxides as possible mechanisms for the limited utilization. From these results, a special role of substrate-linked lipid peroxides in the activation of mucosal prostaglandin synthesis is proposed. The reduction of these peroxides by glutathione dependent or independent peroxidases, e.g. the PGH synthase-linked hydroperoxidase activity itself, could explain the reduced utilization of nonesterified arachidonic acid by the gastric mucosa.     

Reactive oxygen forms and luminescence of intact microspore cells

The participation of reactive oxygen species (ROS) in luminescence (chemiluminescence and autofluorescence induced by ultraviolet light of 360-380 nm) was analyzed. Microspores, the pollen (male gametophyte) of Hippeastrum hybridum, Philadelphus grandiflorus, and Betula verrucosa and vegetative microspores of the spore-breeding plant Equisetum arvense served as models. It was found that the addition of the chemiluminescent probe lucigenin, which luminesces in the presence of superoxide anionradicals, leads to intensive chemiluminescence of microspores. No emission was observed in the absence of lucigenin and in the presence of the dye luminol as a chemiluminescent probe. The emission decreased significantly if superoxide dismutase, an enzyme of the superoxide anionradical dismutation during which this radical disappeared, was added before the dye addition. The autofluorescence intensity of microspores decreased in the presence of both superoxide dismutase and peroxidase, an enzyme destroying hydrogen peroxide and organic peroxides. The most significant effect was noted after the addition of peroxidase, which indicates a greater contribution of peroxides to this type of emission. The fumigation with ozone, which increases the amount of ROS on the cell surface, enhanced the intensity of the chemiluminescence of microspores with lucigenin, but decreased the intensity of the autofluorescence of microspores. Exogenous peroxides (hydrogen peroxide and tert-butylhydroperoxide) stimulated the autofluorescence of pollen and vegetative spores in a concentration-dependent manner. It was shown that the formation of ROS contributes to the luminescence of plant microspores, which reflects their functional state.     

A nonenzymatic method for determination of hydrogen peroxide and organic peroxides

Reduction of hydrogen peroxide and organic peroxides (t-butyl hydroperoxide and linoleic acid hydroperoxide) was achieved with homovanillic acid as hydrogen donor in the presence of the triethylenetetramine-Fe3+ complex. By the catalytic action of this complex, homovanillic acid is oxidized to its fluorescent dimer. Based on this reaction a fluorometric method for the measurement of the hydroperoxides mentioned above is described. The method can be extended to the determination of substrate-enzyme systems that produce hydrogen peroxide, e.g., glucose-glucose oxidase. The method allows the determination of substances such as hydrogen peroxide and t-butyl hydroperoxide with an accuracy and precision of less than 3%. Glucose can be determined with similar precision and an accuracy of 4.7%.     

Limited utilization of exogenous arachidonic acid by the prostaglandin cyclooxygenase in gastric mucosa: The role of protein binding, glutathione peroxidase, and hydrogen peroxides

We investigated the utilization of exogenous ¹⁴C-labelled arachidonic acid by the cyclooxygenase system of the gastric mucosa and its alteration by cytosolic factors, protein binding, glutathione peroxidase (GSH-Px), and hydrogen peroxides.Total prostaglandin (PG) synthesis from gastric microsomes was reduced in a dose- dependent manner to 12% and 68% of controls by increasing amounts of the 105,000g supernatant or albumin (8mg protein/ml), respectively (p<0.01). The inhibitory cytosolic factor was heat labile, protease sensitive, and was retained by a 300,000 Dalton ultrafiltration membrane. Thus, it was likely a protein. Other possible inhibitory mechanisms like protease- or heme-induced destabilization of the cyclooxygenase, haptoglobin-mediated inhibition, or self-inactivation by endogenous substrate were excluded.N-ethylmaleimide (NEM), an agent that alkylates sulfhydryl-groups thereby inhibiting GSH-Px, abolished the inhibitory effect of cytosol in a dose-dependent fashion. In contrast to their inhibition of prostaglandin synthesis, the binding of arachidonic acid by albumin or cytosolic proteins accounted to 75% and 19% under comparable conditions, respectively, however, cytosolic fatty acid binding was unaffected by NEM. Thus, it was concluded that the inhibitory effect of cytosol, in contrast to albumin, was mediated by a sulfhydryl-depending process, probably a GSH-Px. This conclusion was supported by a qualitatively comparable inhibition by a purified GSH-Px from bovine erythrocytes.The inhibitory action of cytosolic proteins was reduced significantly by increasing concentrations or repeated application of arachidonic acid; therefore, cytosolic GSH-Px was likely to affect substrate utilization by the microsomal PGH synthase through reduction of activating substrate peroxides.Similarly, the in vitro formation of cyclooxygenase products by mucosal homogenate or gastric microsomes in the absence of cytosol was limited at substrate concentrations below 80μM, despite sufficient nonesterified arachidonic acid remaining in the incubate. This limitation was mediated only partially by self-inactivation of the prostaglandin cyclooxygenase. Neither N-ethylmaleimide nor repeated application of hydrogen peroxides increased substrate utilization by isolated microsomes, excluding contamination by GSH-Px or simply a lack of hydrogen peroxides as possible mechanisms for the limited utilization. From these results, a special role of substrate-linked lipid peroxides in the activation of mucosal prostaglandin synthesis is proposed. The reduction of these peroxides by glutathione dependent or independent peroxidases, e.g. the PGH synthase-linked hydroperoxidase activity itself, could explain the reduced utilization of nonesterified arachidonic acid by the gastric mucosa.     

Involvement of polyamines in evening primrose extract-induced apoptosis in Ehrlich ascites tumor cells

Summary. We previously demonstrated that evening primrose extract (EPE) induced apoptosis and inhibited the DNA synthesis in Ehrlich ascites tumor cells (EATC) and suggested that EPE-induced inhibition of the growth of EATC are via at least two pathway differentially modulated by reactive oxygen species, notably intracellular peroxides. These are (a) the EPE-induced apoptosis pathway which is dependent on increases in hydrogen peroxide and (b) the EPE-induced inhibition of cell proliferation which is hydrogen peroxide independent. In this study, EPE brought about a significant decrease in intracellular polyamine levels. Furthermore, the addition of polyamines reversed the EPE-induced decrease in cell viability and suppressed the EPE-induced increase in intracellular hydrogen peroxides. However, the addition of polyamines did not reverse EPE-induced decrease in DNA synthesis and phosphorylation of Rb protein, and EPE-induced translocation of AIF. These results suggest the involvement of polyamines in the EPE-induced apoptosis pathway which is dependent on increase in hydrogen peroxide.     

Formation of lipid peroxides in isolated rat liver microsomes by singlet molecular oxygen.

Rat liver microsomes were incubated in neutral aqueous solution of potassium peroxychromate, a system which generates singlet molecular oxygen. Such incubation resulted both in a rapid decline in NADPH-cytochrome c reductase activity, and in an increase in formation of lipid peroxides. These reactions were not inhibited by either superoxide dismutase (SOD) or mannitol, nor were they entirely duplicated by incubating microsomes with hydrogen peroxide. However, a high concentration of 1,4-diazabicyclo-[2,2,2]octane (DABCO), a known scavenger of singlet oxygen, prevented both decline in reductase activity and formation of lipid peroxides. These results suggest that the observed effects are, in fact, attributable to singlet oxygen, and not to hydrogen peroxide, superoxide radical, or hydroxyl radical.     

Ibuprofen protects low density lipoproteins against oxidative modification

Oxidative modification of LDL by vascular cells has been proposed as the mechanism by which LDL become atherogenic. The effect of ibuprofen on LDL modification by copper ions, monocytes and endothelial cells was studied by measuring lipid peroxidation products. Ibuprofen inhibited LDL oxidation in a dose-dependent manner over a concentration range of 0.1 to 2.0 mM. Ibuprofen (2 mM, 100 microg/ml LDL) reduced the amount of lipid peroxides formed during 2 and 6 h incubation in the presence of copper ions by 52 and 28%, respectively. Weak free radical scavenging activity of ibuprofen was observed in the DPPH test. The protective effect of ibuprofen was more marked when oxidation was induced by monocytes or endothelial cells. Ibuprofen (1 mM, 100 microg/ml LDL) reduced the amount of lipid peroxides generated in LDL during monocyte-mediated oxidation by 40%. HUVEC-mediated oxidation of LDL in the absence and presence of Cu2+ was reduced by 32 and 39%, respectively. More lipid peroxides appeared when endothelial cells were stimulated by IL-1beta or TNFalpha and the inhibitory effect of ibuprofen in this case was more pronounced. Ibuprofen (1 mM, 100 microg/ml LDL) reduced the amount of lipid peroxides formed during incubation of LDL with IL-1beta-stimulated HUVEC by 43%. The figures in the absence and presence of Cu2+ for HUVEC stimulated with TNFalpha were 56 and 59%, respectively. To assess the possibility that ibuprofen acts by lowering the production rate of reactive oxygen species, the intracellular concentration of H2O2 was measured. Ibuprofen (1 mM) reduced intracellular production of hydrogen peroxide in PMA-stimulated mononuclear cells by 69%. When HUVEC were stimulated by IL-1beta or TNFalpha the reduction was 62% and 66%, respectively.     

Scavenging of Active Oxygen Species by Glycated Proteins

Scavenging of active oxygen species by glycated proteins was investigated. Glycated proteins were prepared from bovine serum albumin (BSA), insulin, and lysozyme incubated with glucose. Glycated BSA at concentration of 0.5% scavenged 34% of hydroxyl radicals by ESR experiments using DMPO as a spin-trapping reagent. The ability to scavenge hydroxyl radicals by glycated BSA was higher than that by BSA. Hydrogen peroxides also were largely scavenged with an increase in the concentration of glycated proteins. However, the ability to scavenge superoxides by glycated BSA was lower than that by BSA because glycated proteins produced superoxides. Experiments using model compounds such as Amadori compound and caproyl pyrraline suggested that the scavenging ability of glycated proteins against hydroxyl radicals depends on Maillard reaction products in the advanced stage, while the ability against hydrogen peroxides is dependent upon Maillard reaction products in the early stage and brown pigments.     

Antioxidant effects of fructosyl arginine, a Maillard reaction product in aged garlic extract

The amino-carbonyl (Maillard) reaction of amino acids with sugars is a nonenzymatic browning reaction that takes place during the processing, cooking, and storage of foods. Maillard reaction products (MRPs) have been shown to possess interesting chemical and biological properties including antimutagenic and antioxidant activity. In this study, we determined the antioxidant effects of fructosyl arginine (Fru-Arg), a MRP in aged garlic extract. Low density lipoprotein (LDL) was incubated with Cu(2+) at 37 degrees C and 5% CO(2) for 24 hours, which resulted in an increase of thiobarbituric acid reactive substances (TBARS) indicating lipid peroxidation. Coincubation of Cu(2+) with Fru-Arg and LDL resulted in a significant inhibition of TBARS formation. Pulmonary artery endothelial cells (PAEC) were exposed to 0.1 mg/mL oxidized LDL (Ox-LDL) at 37 degrees C and 5% CO(2) for 24 hours. Lactate dehydrogenase (LDH) release, as an index of cell membrane damage, and TBARS were measured. Ox-LDL caused an increase of LDH release and TBARS formation. Pretreatment of PAEC with Fru-Arg inhibited these changes. Murine macrophages were incubated with Ox-LDL, and the release of peroxides was measured using a fluorometric assay. Ox-LDL caused an increased release of peroxides. Coincubation of macrophages with Fru-Arg and Ox-LDL inhibited the release of peroxides dose-dependently. In a cell free system, Fru-Arg was shown to scavenge hydrogen peroxide. These data suggest that Fru-Arg is a potent antioxidant, and thus may be useful for the prevention of atherosclerosis and other disorders associated with oxidative stress.     

Elaboration of cellular DNA breaks by hydroperoxides.

Cellular damage produced by ionizing radiation and peroxides, hydrogen peroxide (HOOH) and the organic peroxides tert-butyl (tBuOOH) or cumene hydroperoxide (CuOOH) were compared. DNA breaks, toxicity, malondialdehyde production, and the rate of peroxide disappearance were measured in a human adenocarcinoma cell line (A549). The alkaline and neutral filter elution assays were used to quantitate the kinetics of single and double strand break formation and repair (SSB and DSB), respectively. Peroxides, at 0.01-1.0 mM, produce multiphasic dose response curves for both toxicity and DNA SSBs. Radiation, 1-6 Gy, produced a shouldered survival curve, and both DNA SSB and DSBs produced in cells x-rayed on ice were nearly linear with dose. The peroxides produced more SSBs than radiation at equitoxic doses. X-ray induced DNA single strand breaks were rejoined rapidly by cells at 37 degrees C with approximately 80% of initial damage repaired in 20 min. Peroxide induced SSBs were maximal after 15 min at 37 degrees C. Rejoining proceeded thereafter, but at a rate less than for x-ray induced strand breaks. Significant DNA DSBs could not be achieved by peroxides even at concentrations 50-fold higher than required to produce SSBs. HOOH treatment of DNA on filters following cell lysis and proteolysis produced SSBs. CuOOH and tBuOOH produced no SSBs in lysed cell DNA. None of the peroxides produced DSBs when incubated with lysed cell DNA. Malondialdehyde was released from cells incubated with organic hydroperoxides, but not HOOH, nor up to 40 Gy of x-rays. HOOH was metabolized three times faster than the organic peroxides. The overall results demonstrate the necessity for a metabolically active cell environment to elaborate maximal DNA strand breaks and cell death at hydroperoxide concentrations of 10(-4) or greater, but prevent strand breaks and stimulate cell growth at 10(-5) M.     

Ferrous ion oxidation in the presence of xylenol orange for detection of lipid hydroperoxide in low density lipoprotein.

A simple and sensitive method for the direct measurement of lipid peroxides in lipoprotein and liposomes is described. The method is based on the principle of the rapid peroxide-mediated oxidation of Fe2+ to Fe3+ under acidic conditions. The latter, in the presence of xylenol orange, forms a Fe(3+)-xylenol orange complex which can be measured spectrophotometrically at 560 nm. Calibration with standard peroxides, such as hydrogen peroxide, linoleic hydroperoxide, t-butyl hydroperoxide, and cumene hydroperoxide gives a mean apparent extinction coefficient of 4.52 x 10(4) M-1 cm-1 consistent with a chain length of approximately 3 for ferrous ion oxidation by hydroperoxides. Endoperoxides are less reactive or unreactive in the assay. The assay has been validated in the study of lipid peroxidation of low density lipoprotein and phosphatidyl choline liposomes. By pretreatment with enzymes known to metabolize peroxides, we have shown that the assay measures lipid hydroperoxides specifically. Other methods for measuring peroxidation, such as the assessment of conjugated diene, thiobarbituric acid reactive substances and an iodometric assay have been compared with the ferrous oxidation-xylenol orange assay.     

Dual method for the determination of peroxidase activity and total peroxides-iodide leads to a significant increase of peroxidase activity in human sera

Peroxidases are very important enzymes, e.g., as preventive antioxidants by removing noxious peroxides from the blood. For this reason we evaluated a colorimetric method which detects the activity of endogenous peroxidases by their reaction with hydrogen peroxide, using tetramethylbenzidine as the chromogenic substrate. This assay design can be easily reversed by change of the variable compound to measure also total peroxides in plasma or serum. An increased total antioxidant status was reported previously by the addition of iodide to human serum. In this study iodide activated the endogenous peroxidases significantly in comparison to control sera and isomolar NaCl as well as horseradish peroxidase. Corresponding to the increased peroxidase activity a concomitant decrease of total peroxides occurred in the same samples. This exchangeable assay design is a beneficial opportunity to screen total peroxide levels as well as peroxidase activity in human sera without time-consuming preparations. The method proved to be simple and is favorable due to its specificity, reproducibility, and low costs. Moreover, we were able to find an explanation for the increased total antioxidant status in the presence of iodide, which is presumably an indirect protective effect via an enhanced activity of enzymatic antioxidants, thereby reducing endogenous peroxides.     

Intermediate Tyrosyl Radical and Amyloid Structure in Peroxide-Activated Cytoglobin

We characterized the peroxidase mechanism of recombinant rat brain cytoglobin (Cygb) challenged by hydrogen peroxide, tert-butylhydroperoxide and by cumene hydroperoxide. The peroxidase mechanism of Cygb is similar to that of myoglobin. Cygb challenged by hydrogen peroxide is converted to a Fe⁴⁺ oxoferryl π cation, which is converted to Fe⁴⁺ oxoferryl and tyrosyl radical detected by direct continuous wave-electron paramagnetic resonance and by 3,5-dibromo-4-nitrosobenzene sulfonate spin trapping. When organic peroxides are used as substrates at initial reaction times, and given an excess of peroxide present, the EPR signals of the corresponding peroxyl radicals precede those of the direct tyrosyl radical. This result is consistent with the use of peroxide as a reducing agent for the recycling of Cygb high-valence species. Furthermore, we found that the Cygb oxidation by peroxides leads to the formation of amyloid fibrils. This result suggests that Cygb possibly participates in the development of degenerative diseases; our findings also support the possible biological role of Cygb related to peroxidase activity.     

Serum vitamins E, A and lipid peroxidation levels in Kurichias, an Indian tribal population.

Serum vitamins E, A, lipid peroxides, prevalence of dislipidemia, hypertension, obesity and smoking habits were assessed in a volunteer sample of 310 (175 males + 135 females) Kurichias, a tribal population of Kerala, India, who are enjoying longevity relatively free from age associated chronic problems. The mean serum levels of vitamins E and A were higher and lipid peroxides were lower with comparable ages of Indian and Western studies. The prevalence (age standardized to the world population of Segi 95% CI) was obesity 2.87 (1.22-4.53), central obesity 3.71 (2.27-5.15), hypertension 2.70 (1.92-3.48), hypercholesterolemia 0.71 (0.66-0.76), hypertriglyceridemia 2.60 (1.18-4.02) and low high density lipoprotein cholesterol 1.24 (1.07-1.42). Significant negative correlation was observed between vitamins and lipid peroxides. Serum cholesterol and triglycerides showed significant positive correlation with antioxidant vitamins and lipid peroxides. Blood pressure found positive correlation with lipid peroxides and no correlation with vitamins except systolic blood pressure having negative relation with vitamin A. Age showed negative correlation with vitamins and positive correlation with lipid peroxides, whereas lipid peroxides showed positive correlation with obesity only. In multivariate regression analysis serum cholesterol and old age groups were significant predictors of serum antioxidant vitamins and lipid peroxides. The higher levels of antioxidant vitamins, lower levels of lipid peroxides as well as low prevalence of CHD risk factors in Kurichias when compared to other populations suggest that antioxidants or increased intake of foods rich in antioxidants play a key role in their health and longevity.