Alpha-tocopherol improves biochemical and dynamic parameters in cryopreserved boar semen

Cryopreservation is associated with the production of reactive oxygen species which lead to lipid peroxidation of sperm membranes. The objective was to determine an alpha-tocopherol concentration capable of improving the quality of cryopreserved porcine semen. Boar spermatozoa frozen with 200, 500 or 1000 microg/mL alpha-tocopherol were thawed and incubated at 37 degrees C for 4 h. Routine parameters of semen quality, susceptibility to lipid peroxidation 2-thiobarbituric acid (TBARS) and oxygen uptake were evaluated. Motility was higher (P<0.05) in samples treated with different concentrations of alpha-tocopherol up to 2 h of incubation. Viability and acrosome integrity significantly decreased during incubation (no significant differences between treatments). Two hundred micrograms per milliliter alpha-tocopherol protected spermatozoa against lipid peroxidation during incubation, but 1000 microg/mL failed to protect after 2 h of incubation. There was a negative association between TBARS and motility, suggesting that lipid peroxidation affected sperm motility. Both control and 200 microg/mL alpha-tocopherol samples preserved the capacity to generate oxidative energy up to 1 h of incubation. The addition of 200 microg/mL alpha-tocopherol in the semen extender could be useful to preserve boar spermatozoa against the oxidative stress generated by cryopreservation.     

Antioxidant and antiradical activities of L-carnitine

L-carnitine plays an important regulatory role in the mitochondrial transport of long-chain free fatty acids. In this study, the antioxidant activity of L-carnitine was investigated as in vitro. The antioxidant properties of the L-carnitine were evaluated by using different antioxidant assays such as 1, 1-diphenyl-2-picryl-hydrazyl free radical (DPPH.) scavenging, total antioxidant activity, reducing power, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. Total antioxidant activity was measured according to ferric thiocyanate method. alpha-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the concentrations of 15, 30 and 45 microg/mL, l-carnitine showed 94.6%, 95.4% and 97.1% inhibition on lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, 45 microg/mL of standard antioxidant such as alpha-tocopherol and trolox indicated an inhibition of 88.8% and 86.2% on peroxidation of linoleic acid emulsion, respectively. In addition, L-carnitine had an effective DPPH. scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, total reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to alpha-tocopherol and trolox as references antioxidants.     

Antioxidant activity of 50% aqueous--ethanol extract from Acantholippia deserticola

The antioxidant properties oí Acantholippia deserticola, a herb used in traditional northern Chilean medicine was studied using free radical-generating systems. The 50% aqueous-ethanol extract oí Acantholippia deserticola protected against non-enzymatic lipid peroxidation in microsomal membranes of rat, induced by an Fe++-ascorbate system and measured spectrophotometrically by the TBARS test, and had strong free radical scavenging capacities on stable ABTS and DPPH radicals. The results shows that the IC50 value of the 50% aqueous-ethanolic extract of A.deserticola is 18 +/- 0.5 microg/mL in DPPH radical-scavenging, 15 +/- 0.8 microg/mL in lipid peroxidation , Total Antioxidant Activity (TAA) is 0.95 mM of Trolox per mg/mL of extract. The total phenolics content of extract is 725 +/- 12 mg of gallic acid equivalent per g of dried extract. The results indicate that the 50% aqueous-ethanol extract of Acantholippia deserticola clearly has antioxidant properties.     

Relevance of apple polyphenols as antioxidants in human plasma: contrasting in vitro and in vivo effects

Apples are a major source of flavonoids in the Western diet, and flavonoid-rich foods may help protect against chronic diseases by antioxidant mechanisms. In the present study we investigated: (1) the antioxidant capacity of representative apple polyphenols and their contribution to the total antioxidant capacity of apple extracts; (2) the effects of adding apple extract to human plasma in vitro on oxidation of endogenous antioxidants and lipids; and (3) the effects of apple consumption by humans on ex vivo oxidation of plasma antioxidants and lipids. We found that the apple-contained flavonols and flavanols, quercetin, rutin, (-)-epicatechin, and (+)-catechin, had a higher antioxidant capacity than the dihydrochalcones, phloridzin and phloretin, and the hydroxycinnamate, chlorogenic acid. However, together these apple polyphenols contributed less than 20% to the total antioxidant capacity of aqueous apple extracts. When human plasma was exposed to a constant flux of aqueous peroxyl radicals, endogenous ascorbate (70.0 +/- 10.3 microM) was oxidized within 45 min of incubation, while endogenous urate (375 +/- 40 microM) and alpha-tocopherol (24.7 +/- 1.2 microM) were oxidized after ascorbate. Addition of 7.1 or 14.3 micrograms/ml total phenols of apple extract did not protect ascorbate from oxidation, but increased the half-life (t1/2) of urate from 136 +/- 15 to 192 +/- 16 and 208 +/- 23 min, respectively (p < 0.05 each), and t1/2 of alpha-tocopherol from 141 +/- 18 to 164 +/- 8 min (p = ns) and 188 +/- 8 min (p < 0.05). Lipid peroxidation started after ascorbate depletion, and addition of apple extract increased the lag time preceding detectable lipid peroxidation from 36.3 +/- 3.7 to 50.9 +/- 2.7 min (p < 0.05) and 70.4 +/- 4.2 min (p < 0.001). However, when six healthy volunteers ate five apples and plasma was obtained up to 4 h after apple consumption, no significant increases in the resistance to oxidation of endogenous urate, alpha-tocopherol, and lipids were found. Thus, despite the high antioxidant capacity of individual apple polyphenols and apple extracts and the significant antioxidant effects of apple extract added to human plasma in vitro, ingestion of large amounts of apples by humans does not appear to result in equivalent in vivo antioxidant effects of apple polyphenols.     

Phytoecdysteroids of Silene guntensis and their in vitro cytotoxic and antioxidant activity

Phytoecdysteroids from aerial parts of Silene guntensis B. Fedtsch were investigated and three phytoecdysteroids were isolated: 2,3-diacetate-22-benzoate-20-hydroxyecdysone (1), 2-deoxy-20-hydroxyecdysone (2), and 20-hydroxyecdysone (3). Their chemical structures were elucidated by DEPT, COSY, 1H and 13C NMR spectroscopy. The isolated compounds 1-3 and crude extracts were evaluated for their antiproliferative and antioxidant activities. They exhibited substantial inhibition of cell growth against human cervix adenocarcinoma (HeLa), hepatocellular carcinoma (HepG-2), and breast adenocarcinoma (MCF-7) cells. The chloroform extract showed potent cytotoxic effects [IC50 values (26.58 +/- 1.88) microg/mL, (20.99 +/- 1.64) microg/mL, and (18.89 +/- 2.36) microg/mL, respectively]. The new compound 1 was mildly cytotoxic compared to extracts [(127.97 +/- 11.34), (106.76 +/- 7.81), and (203.10 +/- 19.56) microg/mL, respectively]. Water and n-butanol extracts exhibited good antioxidant activities [IC50 values of (68.90 +/- 6.45) microg/mL and (69.12 +/- 5.85) microg/mL, respectively].     

Protein glycation inhibitory activities of Lawsonia inermis and its active principles

The protein glycation inhibitory activity of ethanolic extract of Lawsonia inermis (henna) plant tissues was evaluated in vitro using the model system of bovine serum albumin and glucose. Protein oxidation and glycation are posttranslational modifications that are implicated in the pathological development of many age-related disease processes. This study investigated the effects of Lawsonia inermis ethanolic extract and its components, on protein damage induced by a free radical generator in in vitro assay system. We found that alcoholic extract of Lawsonia inermis can effectively protect against protein damage and showed that its action is mainly due to Lawsone. In addition, the presence of gallic acid also plays an important role in the protective activity against protein oxidation and glycation. Two known compounds, namely, Lawsone and gallic acid previously isolated from this plant were subjected to glycation bioassay for the first time. It was found that the alcoholic extract, lawsone (1) and gallic acid (2) showed significant inhibition of Advanced Glycated End Products (AGEs) formation and exhibit 77.95%, 79.10% and 66.98% inhibition at a concentration of 1500 microg/mL, 1000 microg/mL and 1000 microM respectively. Lawsonia inermis, compounds 1 and 2 were found to be glycation inhibitors with IC(50) 82.06 +/- 0.13 microg/mL, 67.42 +/- 1.46 microM and 401.7 +/- 6. 23 microM respectively. This is the first report on the glycation activity of these compounds and alcoholic extract of Lawsonia inermis.     

Antioxidant activity of leaf extracts from Bauhinia monandra

Bauhinia monandra Kurz. is used in Brazil for the treatment of diabetes. Since this activity may be correlated with the presence of antioxidant compounds, leaf extracts of B. monandra were evaluated for their radical scavenging capacity (RSC). An ethanolic extract was taken up in aqueous methanol and partitioned with hexane, chloroform, ethyl acetate to yield three organic extracts together with remaining aqueous extract. The RSC was determined spectrophotometrically using 1,1-diphenylpicrylhydrazyl free radical (DPPH). The chloroform and ethyl acetate extracts were the most appropriate as sources of antioxidant compounds as shown by their inhibition concentration (IC50) and inhibition percentage (IP) values. The antioxidant activity of such extracts was attributed to the presence of three compounds of different polarities (flavonoids and steroids). The chloroform and ethyl acetate extracts exhibited an IC50 of approximately 2 mg/g DPPH and IP values in the range of 60-65%. The results indicate that the extracts of B. monandra have a very potent antioxidant activity, compared with the pure catechins used as positive controls and with other plant extracts.     

Antioxidant and radical scavenging properties of curcumin

Curcumin (diferuoyl methane) is a phenolic compound and a major component of Curcuma longa L. In the present paper, we determined the antioxidant activity of curcumin by employing various in vitro antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH*) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by the Fe(3+)-Fe(2+) transformation method, superoxide anion radical scavenging by the riboflavin/methionine/illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe(2+)) chelating activities. Curcumin inhibited 97.3% lipid peroxidation of linoleic acid emulsion at 15 microg/mL concentration (20 mM). On the other hand, butylated hydroxyanisole (BHA, 123 mM), butylated hydroxytoluene (BHT, 102 mM), alpha-tocopherol (51 mM) and trolox (90 mM) as standard antioxidants indicated inhibition of 95.4, 99.7, 84.6 and 95.6% on peroxidation of linoleic acid emulsion at 45 microg/mL concentration, respectively. In addition, curcumin had an effective DPPH* scavenging, ABTS*(+) scavenging, DMPD*(+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, BHA, BHT, alpha-tocopherol and trolox, were used as the reference antioxidant and radical scavenger compounds. According to the present study, curcumin can be used in the pharmacological and food industry because of these properties.     

Antioxidant activity of L-adrenaline: a structure-activity insight

L-adrenaline belongs to a group of the compounds known as catecholamines, which play an important role in the regulation of physiological process in living organisms. The antioxidant activity and antioxidant mechanism of L-adrenaline was clarified using various in vitro antioxidant assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), N,N-dimethyl-p-phenylenediamine (DMPD(+)), and superoxide anion radicals (O(2)(-)) scavenging activity, hydrogen peroxide (H(2)O(2)), total antioxidant activity, ferric ions (Fe(3+)) and cupric ions (Cu(2+)) reducing ability, ferrous ions (Fe(2+)) chelating activity. L-adrenaline inhibited 74.2% lipid peroxidation of a linoleic acid emulsion at 30 microg/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox displayed 83.3, 82.1, 68.1 and 81.3% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. BHA, BHT, alpha-tocopherol and trolox were used as reference antioxidants and radical scavenger compounds. Moreover, this study will bring an innovation for further studies related to antioxidant properties of L-adrenaline. According to present study, L-adrenaline had effective in vitro antioxidant and radical scavenging activity.     

In vitro antioxidant activity of silymarin

Silymarin, a known standardized extract obtained from seeds of Silybum marianum is widely used in treatment of several diseases of varying origin. In the present paper, we clarified the antioxidant activity of silymarin by employing various in vitro antioxidant assay such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH(.)) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by Fe3+ - Fe2+ transformation method and Cuprac assay, superoxide anion radical scavenging by riboflavin/methionine/illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe2+) chelating activities. Silymarin inhibited 82.7% lipid peroxidation of linoleic acid emulsion at 30 microg/mL concentration; butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox indicated inhibition of 83.3, 82.1, 68.1 and 81.3% on peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, silymarin had an effective DPPH(.) scavenging, ABTS(.)+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power by Fe3+-Fe2+ transformation, cupric ions (Cu2+) reducing ability by Cuprac method, and ferrous ions (Fe2+) chelating activities. Also, BHA, BHT, alpha-tocopherol and trolox, were used as the reference antioxidant and radical scavenger compounds. Moreover, this study, which clarifies antioxidant mechanism of silymarin, brings new information on the antioxidant properties of silymarin. According to the present study, silymarin had effective in vitro antioxidant and radical scavenging activity. It could be used in the pharmacological and food industry because of its antioxidant properties.     

Comparison of in vitro antioxidant and antiradical activities of L-tyrosine and L-Dopa

Summary. Phenolic compounds are interesting because of their antioxidant properties. In the present study, the antioxidant properties of L-tyrosine as a monophenolic and L-Dopa as a diphenolic amino acid were investigated by using different antioxidant assays: (i) 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH^•) scavenging; (ii) 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization assay; (iii) total antioxidant activity by ferric thiocyanate method; (iv) ferric ions (Fe³⁺) reducing power; (v) superoxide anion radical (O₂ ^•−) scavenging; (vi) hydrogen peroxide (H₂O₂) scavenging, and (vii) ferrous ions (Fe²⁺) chelating activities. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the same concentration (20 μg/mL), L-tyrosine and L-Dopa showed 30.6 and 67.9% inhibition of lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, BHA, BHT, α-tocopherol and trolox indicated inhibitions of 74.4, 71.2, 54.7 and 20.1% on the peroxidation of linoleic acid emulsion, respectively, at the above-mentioned concentration. In addition, L-tyrosine and L-Dopa had an effect on DPPH radical scavenging, ABTS radical scavenging, superoxide anion radical scavenging, H₂O₂ scavenging, total ferric ions reducing power and metal chelating on ferrous ions activities.     

Antioxidant and Prooxidant Effects of Ascorbic Acid, Dehydroascorbic Acid and Flavonoids on LDL Submitted to Different Degrees of Oxidation

Although a high intake of antioxidants may decrease the risk of developing cardiovascular diseases, under certain circunstances they may promote free radical generation and lipid peroxidation. The objectives of the present study were to determine the antioxidant effects of ascorbic acid (AA), dehydroascorbic acid (DHA) and flavonoids on LDL submitted to different degrees of oxidation. LDL was submitted to oxidation with CuCl₂ (2.4 μM). Before or at different times after the propagation of the oxidation process, 28 μM (5 μg/ml) of either AA or DHA or 5 μg/mL flavonoids extract were added. Alpha-tocopherol, conjugated dienes, thiobarbituric acid reacting substances (TBARS) and LDL electrophoretic mobility were determined as indices of LDL oxidation. The presence of any of the three antioxidants from the onset of the incubation delayed the oxidation process. However, the addition of both DHA and flavonoids to the oxidation process when it was already initiated and alpha-tocopherol consumed, accelerated the oxidation. In contrast, AA delayed the oxidation process even when added after alpha-tocopherol was consumed. Nevertheless, it also accelerated LDL oxidation when added during the propagation phase of the oxidation process. In conclusion: although AA, DHA and flavonoids delay LDL oxidation when added before the initiation of the process, they accelerate the process if added to minimally oxidized LDL.     

Total antioxidant performance: a validated fluorescence assay for the measurement of plasma oxidizability

The antioxidant capacity of human plasma was determined by following the oxidation kinetics of the lipid-soluble fluorescent marker BODIPY using 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (MeO-AMVN) as the lipophilic radical initiator. The results are expressed as a total antioxidant performance (TAP) value based on the inhibition of BODIPY oxidation, as determined by the appearance of green fluorescence, with respect to a control sample (phosphatidylcholine with or without delipidized human serum). The suitability of the assay was evaluated on the basis of its precision, reproducibility, and specificity. The intra- and interassay coefficients of variation both were less than 5%. The addition of a representative substrate of plasma peroxidation, phosphatidylcholine, up to 750mug/ml did not induce significant changes in the TAP value. Also, BODIPY photooxidation was not observed during the experimental time course (220min). The TAP values of 6 plasma samples from healthy donors were measured and correlated with the main plasma water- and lipid-soluble antioxidants (uric acid and ascorbic acid, alpha-tocopherol, and carotenoids) and lipid profiles. Significant correlations were found between TAP and uric acid (R=0.97, P<0.05) and cholesterol-adjusted alpha-tocopherol (R=0.93, P<0.01). The results confirm that the TAP assay is suitable to measure the antioxidant activity of plasma antioxidants localized in both the lipophilic and hydrophilic compartments.     

Antioxidant potentials and rosmarinic acid levels of the methanolic extracts of Salvia virgata (Jacq), Salvia staminea (Montbret & Aucher ex Bentham) and Salvia verbenaca (L.) from Turkey

This study was designed to examine the in vitro antioxidant activities and rosmarinic acid levels of the methanol extracts of Salvia virgata, Salvia staminea and Salvia verbenaca. The extracts were screened for their possible antioxidant activity by two complementary test systems, namely DPPH free radical scavenging and beta-carotene/linoleic acid systems. In the first case, the most active plant was S. verbenaca (14.30+/-1.42 microg mg(-1)), followed by S. virgata (65.70+/-2.12 microg mg(-1)). S. staminae exhibited the weakest antioxidant activity in this test system of which IC(50) value is 75.40+/-0.57 microg mg(-1). In beta-carotene/linoleic acid test system, S. verbenaca extract was superior to the other extracts studied (inhibition value is 77.03%+/-0.42). Antioxidant activities of BHT, ascorbic acid, curcumin and alpha-tocopherol were determined in parallel experiments. Activity of rosmarinic acid was also screened for better establishing the relationship between rosmarinic acid level and antioxidant activity for the plant extracts. According to the results obtained by spectrophotometric analysis and further supported by HPLC, S. verbenaca has the highest rosmarinic acid level with a value of 29.30+/-0.24 microg mg(-1). Our results showed that the rosmarinic acid and its derivatives are more likely to be responsible for most of the observed antioxidant activities of Salvia species.     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO*), superoxide anion (O2*-), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC50 = 2.3 +/- 0.2 and 1.9 +/- 0.1 microg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 +/- 0.2 and 0.2 +/- 0.1 microg/ml, respectively), and also showed a considerable antioxidant activity against O2*- (87.3 +/- 0.1 and 73.1 +/- 0.4 microg/ml, respectively) and DPPH radicals (55.4 +/- 0.3 and 38.3 +/- 0.4 microg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl4 significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl4 in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

Iron chelation and related properties of Podophyllum hexandrum, a possible role in radioprotection

Aqueous extract of Podophyllum species has been reported to render significant protection against radiation induced mortality, cytogenetic damage and cell death. In view of this, present study was undertaken to investigate its antioxidant properties. Chelation, oxidation and reduction of Fe2+ and Fe3+ were measured using chelating agents 2-2' bipiridyl and potassium thiocyanate respectively. Podophyllum extract, in a dose dependent manner, chelated Fe2+ more efficiently than Fe3+ and also modulated Fe2+/Fe3+ ratio. Homogenate of mouse liver was used to measure TBARS for estimating lipid peroxidation. Podophyllum extract also inhibited lipid peroxidation in a dose dependent manner and maximum inhibition (92%) was achieved at 1000 micrograms/ml concentration. These results demonstrates that Podophyllum exhibits antioxidant properties as seen through chelation and modulation of redox state of iron ions and these may primarily contribute towards its radioprotective manifestation.     

In vitro antiproliferative, apoptotic and antioxidant activities of punicalagin, ellagic acid and a total pomegranate tannin extract are enhanced in combination with other polyphenols as found in pomegranate juice

Pomegranate (Punica granatum L.) fruits are widely consumed as juice (PJ). The potent antioxidant and anti-atherosclerotic activities of PJ are attributed to its polyphenols including punicalagin, the major fruit ellagitannin, and ellagic acid (EA). Punicalagin is the major antioxidant polyphenol ingredient in PJ. Punicalagin, EA, a standardized total pomegranate tannin (TPT) extract and PJ were evaluated for in vitro antiproliferative, apoptotic and antioxidant activities. Punicalagin, EA and TPT were evaluated for antiproliferative activity at 12.5-100 microg/ml on human oral (KB, CAL27), colon (HT-29, HCT116, SW480, SW620) and prostate (RWPE-1, 22Rv1) tumor cells. Punicalagin, EA and TPT were evaluated at 100 microg/ml concentrations for apoptotic effects and at 10 microg/ml concentrations for antioxidant properties. However, to evaluate the synergistic and/or additive contributions from other PJ phytochemicals, PJ was tested at concentrations normalized to deliver equivalent amounts of punicalagin (w/w). Apoptotic effects were evaluated against the HT-29 and HCT116 colon cancer cell lines. Antioxidant effects were evaluated using inhibition of lipid peroxidation and Trolox equivalent antioxidant capacity (TEAC) assays. Pomegranate juice showed greatest antiproliferative activity against all cell lines by inhibiting proliferation from 30% to 100%. At 100 microg/ml, PJ, EA, punicalagin and TPT induced apoptosis in HT-29 colon cells. However, in the HCT116 colon cells, EA, punicalagin and TPT but not PJ induced apoptosis. The trend in antioxidant activity was PJ>TPT>punicalagin>EA. The superior bioactivity of PJ compared to its purified polyphenols illustrated the multifactorial effects and chemical synergy of the action of multiple compounds compared to single purified active ingredients.     

Dietary antioxidants as inhibitors of the heme-induced peroxidation of linoleic acid: mechanism of action and synergism

In this work, a quantitative kinetic model for investigating the heme-induced peroxidation of linoleic acid and its inhibition by two important dietary antioxidants, quercetin and alpha-tocopherol, is developed. The main conclusions of this work are: (1) The time dependence of the lipid hydroperoxide concentration is critically dependent on the rate constant for lipid hydroperoxide cleavage, initial fraction of lipid hydroperoxides among the pool of conjugated dienes, and rate of heme degradation. (2) The lipophilic antioxidant alpha-tocopherol acts as a chain-breaking antioxidant that quickly reduces 1-2 eq of lipid peroxyl radicals (inhibition of propagation), whereas the more hydrophilic antioxidant quercetin is only marginally chain-breaking but capable of reducing 4-5 eq of iron-oxo initiator (inhibition of initiation). (3) Based on comparisons between experimental peroxidation curves and simulated curves assuming additivity, it can be concluded that combinations of alpha-tocopherol and quercetin are generally synergistic. The kinetic analysis and HPLC titrations of the antioxidants both suggest that synergism mainly arises from a capacity of alpha-tocopherol to regenerate some quercetin oxidation products still endowed with a reducing activity.     

南瓜醇提物的体外抗氧化活性(英文)

采用化学体系模拟法体外测定南瓜醇提物((pumpkin ethanol extract,PEE)对1,1-二苯基-2-苦苯肼自由基(DPPH·)、超氧阴离子自由基(O2)和羟自由基(·OH)的清除能力,总还原力,对β-胡萝卜素/亚油酸自氧化体系的总抗氧化能力以及脂质过氧化的抑制能力.结果显示PEE对DPPH·、02-和·OH均有较强的清除能力,IC50值分别为18.8 mg/mL、29.0 ms/mL和44.9μg/mL,有显著的还原力和总抗氧化力,对脂质过氧化有一定的抑制作用.PEE的体外抗氧化活性均有良好的量效关系.上述结果为南瓜作为抗氧化的保健食品或功能食品开发利用提供了依据.     

Total phenolics concentration and antioxidant potential of extracts of medicinal plants of Pakistan

Thirty-seven plant organs, traditionally used as drugs, collected in Pakistan, were extracted with 70% acetone and analyzed for their total phenolics concentration and antioxidant potential. Seven extracts showed more than 85% inhibition of lipid peroxidation in vitro as compared with blank. Butylated hydroxytoluene (BHT) (IC50 = 233.6 microg/l +/- 28.3) was the strongest antioxidant in our test system. The IC50 results indicate that the extracts of Nymphaea lotus L. flowers, Acacia nilotica (Linn.) Delile beans, Terminalia belerica Roxb. fruits, and Terminalia chebula Retz. (fruits, brown) were stronger antioxidants than alpha-tocopherol, while Terminalia chebula Retz. (fruit coat), Terminalia chebula Retz. (fruits, black) and Ricinus communis L. leaves were weaker antioxidant extracts than alpha-tocopherol and BHT. Total phenolics concentration, expressed as gallic acid equivalents, showed close correlation with the antioxidant activity. High performance liquid chromatographic analysis with diode array detection at 280 nm, of the seven extracts indicated the presence of hydroxybenzoic acid derivatives, hydroxycinnamic acid derivatives, flavonol aglycones and their glycosides as main phenolics compounds. This information, based on quick screening methods, enables us to proceed towards more detailed chemical and pharmacological understanding of these plant materials.