Deoxyribose Degradation Research Articles

Radioprotective properties of apple polyphenols: An in vitro study

Present study was undertaken to evaluate the radioprotective ability of total polyphenols extracted from edible portion (epicarp and mesocarp) of apple. Prior administration of apple polyphenols to murine thymocytes significantly countered radiation induced DNA damage (evaluated by alkaline halo assay) and cell death (trypan blue exclusion method) in a dose dependent manner maximally at a concentration of 2 and 0.2 mg/ml respectively. Apple polyphenols in a dose dependent fashion inhibited both radiation or Fenton reaction mediated 2-deoxyribose (2-DR) degradation indicating its ability to scavenge hydroxyl radicals and this activity was found to be unaltered in presence of simulated gastric juice. Similarly apple polyphenols in a dose dependent fashion scavenged DPPH radicals (maximum 69% at 1 mg/ml), superoxide anions (maximum 88% at 2 mg/ml), reduced Fe(3 +) to Fe(2 +) (maximum at 1 mg/ml) and inhibited Fenton reaction mediated lipid peroxidation (maximum 66% at 1.5 mg/ml) further establishing its antioxidative properties. Studies carried out with plasmid DNA revealed the ability of apple polyphenols to inhibit radiation induced single as well as double strand breaks. The results clearly indicate that apple polyphenols have significant potential to protect cellular system from radiation induced damage and ability to scavenge free radicals might be playing an important role in its radioprotective manifestation.

Bioactive 1,4-dihydroisonicotinic acid derivatives prevent oxidative damage of liver cells

1,4-Dihydroisonicotinic acid derivatives (1,4-DHINA) are compounds closely related to derivatives of 1,4-dihydropyridine, a well-known calcium channel antagonists. 1,4-DHINA we used were derived from a well-known antioxidant Diludin. Although some compounds have neuromodulatory or antimutagenic properties, their activity mechanisms are not well known. This study was performed to obtain data on antioxidant and bioprotective activities of: 2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydroisonicotinic acid (Ia); sodium 2-(2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine-4-carboxamido)glutamate (Ib) and sodium 2-(2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine-4-carboxamido)ethane-sulphate (Ic). 1,4-DHINA's activities were studied in comparison to Trolox by: N, N-Diphenyl- N′-picrylhydrazyl (DPPH ), deoxyribose degradation, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical scavenging and antioxidative capacity assays; copper-induced lipid peroxidation of cultured rat liver cells (malondialdehyde determination by high performance liquid chromatography and 4-hydroxynonenal-protein conjugates by dot-blot); 3H-thymidine incorporation and trypan blue assay for liver cells growth and viability. In all assays used Ia was the most potent antioxidant. Ia was also a potent antioxidant at non-toxic concentrations for liver cell cultures. It completely abolished, while Ic only slightly decreased copper-induced lipid peroxidation of liver cells. Thus, antioxidant capacities are important activity principle of Ia, which was even superior to Trolox in the cell cultures used, while activity principles of Ic and Ib remain yet to be determined.

Antioxidant activity of Gymnema inodorum Decne. (Pak chiang daa) and its effect on DNA damage in TK6 human lymphoblastoid cells

Gymnema inodorum Decne. (Pak chiang daa, GI) is one of Thai herbs that have been popularly consumed and used as herbal remedy in the northern Thailand. It has been shown that GI contains high amount of phenolic compounds as well as beta-carotene, vitamin E and C. This study was conducted to determine the antioxidant activity of GI and whether it protects cells against DNA damage. Edible parts of GI were prepared as fresh juice (GIJ) and dried forms, which were extracted further with either water (GIW) or 50% ethanol (GIE). The antioxidant activity of all extracts was determined by 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, deoxyribose degradation assay, and hemolysis assay. The effect of the GI extracts on DNA damage was examined by the comet assay in TK6 human lymphoblastoid cells. The results showed that GIJ had the highest antioxidant activity compared with GIW and GIE (IC50 values were 0.25 ± 0.02, 0.40 ± 0.02, and 0.33 ± 0.04 mg/mL (DPPH assay); 0.15 ± 0.07, 0.29 ± 0.03, and 0.27 ± 0.05 mg/mL (deoxyribose assay); 0.15 ± 0.23, 0.24 ± 0.37, and 0.29 ± 0.21 mg/mL (hemolysis assay), respectively). The highest inhibitory effect on DNA damage was found in GIJ compared with GIW and GIE (78.02%, 40.38% and 50.54%, respectively). This study suggests that the fresh preparation of GI can be used as an effective antioxidant.

All-trans retinoic acid induces free radical generation and modulate antioxidant enzyme activities in rat sertoli cells

In this work we investigated the effects of retinoic acid (RA) in Sertoli cells. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with RA for 24 h. RA at high doses (1-10 microM) increased TBARS levels and induced a decrease in cell viability. At low doses (0.1-100 nM) RA did not increase TBARS level. RA also did not increase cell death at these doses. In order to investigate changes in antioxidant defenses we measured the CAT, SOD and GPx activities in Sertoli cells treated with RA. Compared to control, RA increased around 200% SOD activity in all doses tested (0.1-100 nM); GPx activity was increased 407.49, 208.98 and 243.88% (0.1, 1 and 10 nM, respectively); CAT activity was increased 127% with RA 1 nM. To clarify if RA induces ROS production per se, we performed experiments in vitro using 2-deoxyribose as specific substrate of oxidative degradation by *OH radical as well as TRAP assay. RA at 10 microM increased 2-deoxyribose degradation, suggesting that some of the RA-induced effects are mediated via *OH formation. Furthermore, the total reactive antioxidant potential (TRAP) of the RA was determined. At low concentrations RA has induced no redox activity. Conversely, higher concentration of RA (1-10 microM) increased chemiluminescence. The chemiluminescence produced was directly proportional to radical generation. We provide, for the first time, evidence for a free radical generation by RA. Our results demonstrated that RA plays an important role in Sertoli cells and these effects appear to be mediated by ROS.

Mangifera indica L. extract (Vimang®) inhibits 2‐deoxyribose damage induced by Fe (III) plus ascorbate

Vimang is an aqueous extract of selected species of Mangifera indica L, used in Cuba as a nutritional antioxidant supplement. Many in vitro and in vivo models of oxidative stress have been used to elucidate the antioxidant mechanisms of this extract. To further characterize the mechanism of Vimang action, its effect on the degradation of 2-deoxyribose induced by Fe (III)-EDTA plus ascorbate or plus hypoxanthine/xanthine oxidase was studied. Vimang was shown to be a potent inhibitor of 2-deoxyribose degradation mediated by Fe (III)-EDTA plus ascorbate or superoxide (O2-). The results revealed that Vimang, at concentrations higher than 50 microM mangiferin equivalent, was equally effective in preventing degradation of both 15 mM and 1.5 mM 2-deoxyribose. At a fixed Fe (III) concentration, increasing the concentration of ligands (either EDTA or citrate) caused a significant reduction in the protective effects of Vimang. When ascorbate was replaced by O2- (formed by hypoxanthine and xanthine oxidase) the protective efficiency of Vimang was also inversely related to EDTA concentration. The results strongly indicate that Vimang does not block 2-deoxyribose degradation by simply trapping *OH radicals. Rather, Vimang seems to act as an antioxidant by complexing iron ions, rendering them inactive or poorly active in the Fenton reaction.

L-Dopa− and Dopamine−(R)-α-Lipoic Acid Conjugates as Multifunctional Codrugs with Antioxidant Properties

A series of multifunctional codrugs (1-4), obtained by joining L-Dopa (LD) and dopamine (DA) with (R)-alpha-lipoic acid (LA), was synthesized and evaluated as potential codrugs with antioxidant and iron-chelating properties. These multifunctional molecules were synthesized to overcome the pro-oxidant effect associated with LD therapy. The physicochemical properties, together with the chemical and enzymatic stabilities of synthesized compounds, were evaluated in order to determine both their stability in aqueous medium and their sensitivity in undergoing enzymatic cleavage by rat and human plasma to regenerate the original drugs. The new compounds were tested for their radical scavenging activities, using a test involving the Fe (II)-H2O2-induced degradation of deoxyribose, and to evaluate peripheral markers of oxidative stress such as plasmatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the plasma. Furthermore, we showed the central effects of compounds 1 and 2 on spontaneous locomotor activity of rats in comparison with LD-treated animals. From the results obtained, compounds 1-4 appeared stable at a pH of 1.3 and in 7.4 buffered solution; in 80% human plasma they were turned into DA and LD. Codrugs 1-4 possess good lipophilicity (log P > 2 for all tested compounds). Compounds 1 and 2 seem to protect partially against the oxidative stress deriving from auto-oxidation and MAO-mediated metabolism of DA. This evidence, together with the "in vivo" dopaminergic activity and a sustained release of the parent drug in human plasma, allowed us to point out the potential advantages of using 1 and 2 rather than LD in treating pathologies such as Parkinson's disease, characterized by an evident decrease of DA concentration in the brain.

Characterization of the phenolic constituents in Mauritian endemic plants as determinants of their antioxidant activities in vitro

The phenolic constituents of Mauritian endemic plants from the Rubiaceae and Myrtaceae family were assessed and correlated with their potential antioxidant activities in vitro. The antioxidant activities of the plant extracts ranged from 0.27 to 1.49mmol Trolox equivalent/g FW and from 0.20 to 1.39mmol Fe(II) equivalent/g FW in the TEAC and FAP assays, respectively, with Syzygium commersonii showing the highest activity in these two systems. Eugenia orbiculata and all the Syzygium species were effective scavengers of hypochlorous acid while Monimiastrum acutisepalum was the most potent inhibitor of deoxyribose degradation. The plant extracts inhibited microsomal lipid peroxidation with low IC(50)s ranging from 0.02 to 1.75mgFW/mL when reaction was initiated with Fe(3+)/ascorbate and from 0.093 to 1.55mgFW/mL in the AAPH-dependent lipid peroxidation. The potential prooxidant nature of the plant extracts was compared with ascorbate (250microM) using copper-phenanthroline assay. The plant extracts at concentrations up to 5gFW/L were not prooxidant. However, Myonima nitens, Syzygium commersonii, Syzygium glomeratum and Syzygium mauritianum at concentrations of 10gFW/L had potency approaching 50% of the prooxidant activity of ascorbic acid in vitro, suggesting relative safeties. The total phenolics influenced the antioxidant activities in the TEAC, FRAP and HOCl scavenging assays whereas a negative correlation was observed with the deoxyribose assay. The high levels of polyphenolic compounds and the significant antioxidant activities of these Rubiaceae and Myrtaceae plant family make them suitable candidates as prophylactic agent.

Antioxidant properties of different fractions of Vitex negundo Linn.

Vitex negundo Linn. (VN), belonging to family Verbenaceae, is an aromatic shrub distributed throughout India. In the ayurvedic system of medicine it is used as a drug of choice to manage pain, inflammation and other related diseases. It contains many polyphenolic compounds, terpenoids, glycosidic iridoids and alkaloids. Since polyphenolic compounds have high antioxidant potential, the antioxidant potency of V. negundo was investigated by employing various established in vitro systems, such as 2,2′-azino-bis 3-ethyl benzothiazoline-6-sulfuric acid (ABTS ∗+)/Lipid Peroxides (LPO)/Superoxide/Hydroxyl radical scavenging and iron ion chelation. Total antioxidant capacity was determined by the assay based on the preformed radical monocation ABTS ∗+. Lipid peroxidation was assessed in terms of thiobarbituric acid reactive substances by using egg yolk homogenates as lipid rich media. Superoxide radical scavenging assay was based on the riboflavin-light-Nitro blue tetrazolium (NBT) system. Hydroxyl radical trapping potential was determined by evaluating hydroxyl radical induced deoxyribose degradation using the thiobarbituric acid method. In order to assess the metal chelation properties, hydroxyl radical induced deoxyribose degradation was evaluated in the absence of Ethylenediamine tetra acetic acid (EDTA). All the polar fractions significantly showed trapping of free radicals, and thereby inhibition of lipid peroxidation, and also chelated the iron ion. Interestingly, the hexane fraction did not show any activity against superoxides radicals and it had minimum trapping potential for other free radical (FR) species also. Thus, it may be concluded that the polar fractions of VN possess potent antioxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation. Therefore its reported anti-inflammatory properties, could be through the down regulation of the free radical mediated pathway of inflammation.

Anti‐oxidant and pro‐oxidant behaviour of bucillamine

Bucillamine (BUC) is used clinically for the treatment of rheumatoid arthritis. Some of the pharmacological action of BUC has been reported as being dependent on the production of reactive oxygen species (ROS). In this paper the reactivity of BUC with superoxide anion radical (O(2) (*-)) generated from potassium superoxide/18-crown-6 ether dissolved in DMSO, hydroxyl radical (HO(*)) produced in the Cu(2+)-H(2)O(2) reaction, peroxyl radical (ROO(*)) from 2,2'-azobis (2-amidino-propane) dichloride decomposition, and singlet oxygen ((1)O(2)) from a mixture of alkaline aqueous H(2)O(2) and acetonitrile, have been investigated. Chemiluminescence, fluorescence, electron paramagnetic resonance (EPR) spin-trapping techniques and the deoxyribose and oxygen radical absorbance capacity towards ROO(*) (ORAC(ROO)) assays were used to elucidate the anti- and pro-oxidative behaviours of BUC towards ROS. The results indicated that BUC efficiently inhibited chemiluminescence from the O(2) (*-)-generating system at relatively high concentrations (0.5-2 mmol/L); however, at lower concentrations (<0.5 mmol/L) the drug enhanced light emission. The behaviour of BUC was correlated with a capacity to decrease the chemiluminescence signal from the Cu(2+)-H(2)O(2) system; scavenging HO(*) was effective only at high concentrations (1-2 mmol/L) of the drug. Bucillamine also prevented deoxyribose degradation induced by HO(*) in a dose-dependent manner, reaching maximal inhibition (24.5%) at a relative high concentration (1.54 mmol/L). Moreover, BUC reacts with ROO(*); the relative ORAC(ROO) was found to be 0.34 micromol/L Trolox equivalents/micromol sample. The drug showed quenching of (1)O(2)-dependent 2,2,6,6-tetramethylpiperidine-N-oxide radical formation from 2,2,6,6-tetramethyl-piperidine (e.g. 90% inhibition was found at 1 mmol/L concentration). The results showed that BUC may directly scavenge ROS or inhibit reactions generating them. However, the drug may have pro-oxidant activity under some reaction conditions.

Dual mechanism of mangiferin protection against iron-induced damage to 2-deoxyribose and ascorbate oxidation

We studied mangiferin effects on the degradation of 2-deoxyribose induced by Fe(III)–EDTA/citrate plus ascorbate, in relation to ascorbate oxidation (measured at 265 nm). Results revealed that mangiferin was equally effective in preventing degradation of both 15 and 1.5 mM 2-deoxyribose. At a fixed Fe(III) concentration, increasing the concentration of ligands (either EDTA or citrate) caused a significant reduction in the protective effects of mangiferin. Interestingly, mangiferin strongly stimulated Fe(III)–EDTA ascorbate oxidation, but inhibited it when citrate was used as iron co-chelator. Mangiferin stimulated O 2 consumption due to Fe(II) (formed by Fe(III) ascorbate reduction) autoxidation when the metal ligand was EDTA, but inhibited it when citrate was used. These results suggest that mangiferin removes iron from citrate, but not from EDTA, forming an iron–mangiferin complex that cannot induce ascorbate oxidation effectively, thus inhibiting iron-mediated oxyradical formation. Taken together, these results indicate that mangiferin works mainly by a mechanism different from the classical hydroxyl radical scavengers, keeping iron in its ferric form, by complexing Fe(III), or stimulating Fe(II) autoxidation.

Activity of Oligoresveratrols from Stem Bark of Hopea mengarawan (Dipterocarpaceae) as Hydroxyl Radical Scavenger

Four oligoresveratrols ranging from dimer to tetramer, isolated from stem bark of Hopea mengarawan (Dipterocarpaceae) plants were tested for their activity as hydroxyl radical scavenger. The activity of these compounds was evaluated against the 2-deoxyribose degradation induced by the hydroxyl radical generated via a Fenton-type reaction. Result showed that balanocarpol, heimiol A, vaticanol G, and vaticanol B had IC 50 3.83; 15.44; 2.01; and 4.71 uM, respectively. These results suggest that oligoresveratrols from stem bark of H. mengarawan maybe useful as potential sources of natural antioxidants. Key words: Oligoresveratrol, Hopea mengarawan

Antioxidative properties of bee pollen in selected plant species

Phenolic constituents (total phenols, phenylpropanoids, flavonols and anthocyanins) and antioxidant ability were determined in bee pollen of 12 plant species. Antioxidant ability was measured as total antioxidant activity, radical-scavenging activity and activity against free hydroxyl radical. Great variability of phenolic contents was observed in the pollen of investigated species. Total antioxidant activity differed considerably (0.8–86.4% inhibition of lipid peroxidation), however, in most of the examined pollens, it was high and corresponded with the phenylpropanoid level. Great differences in the radical-scavenging activity (8.6–91.5% of DPPH neutralization) and in the hydroxyl radical-scavenging activity (10.5–98% inhibition of deoxyribose degradation) were observed and were not correlated with the content of phenolic compounds. In most of the investigated plant species, antioxidative capacity of bee pollen was very high.

Antioxidant and Pro-oxidant Activities of Aqueous Extracts and Crude Polyphenolic Fractions of Rooibos (Aspalathus linearis)

Unfermented rooibos tea is known to contain higher levels of total polyphenols and flavonoids than its fermented counterpart, making it the obvious choice for the preparation of flavonoid-enriched fractions. Evaluation of aqueous extracts and crude polyphenolic fractions of unfermented and fermented rooibos showed anti- and/or pro-oxidant activities, using a linoleic acid-Tween-buffer emulsion for lipid peroxidation and the deoxyribose degradation assay, based on a Fenton reaction model system containing FeCl3-EDTA and H2O2 for the generation of hydroxyl radicals. Except for the ethyl acetate fraction, with the highest total polyphenol (TP) content and offering the least protection presumably due to pro-oxidant activity, the inhibition of lipid peroxidation by the samples correlated moderately with their TP content in a linear relationship (r = 0.896, P < 0.01). Using the deoxyribose degradation assay, the pro-oxidant activity of the aqueous extracts and their crude polymeric fractions (0.1 mg/mL in the reaction mixture) was linear with respect to their dihydrochalcone (aspalathin and nothofagin) (r = 0.977, P = 0.023) and flavonoid (r = 0.971, P = 0.029) content. Pro-oxidant activity was demonstrated for pure aspalathin. Using the same assay, but with ascorbate added to regenerate Fe3+ to Fe2+, the aqueous extract and crude polymeric fraction of fermented rooibos displayed hydroxyl radical scavenging activity. Fermentation (i.e., oxidation) of rooibos decreased the pro-oxidant activity of aqueous extracts, which was contributed to a decrease in their dihydrochalcone content. The in vitro pro-oxidant activity displayed by flavonoid-enriched fractions of rooibos demonstrates that one must be aware of the potential adverse biological properties of potent antioxidant extracts utilized as dietary supplements.

Scavenging of reactive oxygen species by some nonsteroidal anti‐inflammatory drugs and fenofibrate

Ketoprofen and tolmetin are widely used nonsteroidal anti-inflammatory drugs, whereas fenofibrate belongs to a family of hypolipidemic drugs used in the prevention of cardiovascular diseases. The aim of this study was to assess effect of these drugs on reactions generating reactive oxygen species (ROS). The following generators of ROS were used: 18-crown-6/KO(2) dissolved in DMSO as a source of superoxide radical (O(.-)(2), the Fenton-like reaction (Cu/H(2)O(2)) for hydroxyl radical (HO(.)), 2,2'-azobis (2-amidino-propane) dichloride (AAPH) as peroxyl radical (ROO(.)) generator, and a mixture of alkaline aqueous H(2)O(2) and acetonitrile for singlet oxygen ((1)O(2)). Measurements were done using chemiluminescence, fluorescence, and spin-trapping with 2,2,6,6-tetramethylpiperidine combined with electron spin resonance spectroscopy (ESR), and a deoxyribose assay based on the spectrophotometry. The results obtained demonstrated that all tested drugs were active against O(.-)(2). There was a clear ranking of drug inhibition effects on chemiluminescence from the O(.-)(2) system: ketoprofen > tolmetin > fenofibrate. The examined compounds inhibited the HO(.)-dependent deoxyribose degradation and scavenged the ROO(.) concentration dependently with an order of potencies similar to that of the superoxide radical system. Hence, these results indicate that the studied drugs show broad ROS scavenging property and, as a consequence, might decrease tissue damage due to the ROS and thus to contribute to anti-inflammatory therapy.

3-O-β-ᴅ-Galactopyranoside of Quercetin as an Active Principle from High Altitude Podophyllum hexandrum and Evaluation of its Radioprotective Properties

The aqueous-ethanolic extract (AEE) of high altitude Podophyllum hexandrum has earlier been reported to render a radioprotective effect against lethal gamma radiation in in vitro model. AEE has also been reported to possess metal chelating and DNA protecting properties. The present study was undertaken to isolate and characterize the bioactive principle present in AEE and investigate its role in radiation protection. A novel molecule was found to be present in AEE and was assigned as 3-O-beta-D-galactoside of quercetin by acid hydrolysis, LC-MS, LC-APCI-MS/MS and 13C NMR spectra. Various biological activities were investigated at in vitro level. The antioxidant potential of AEE in lipid and aqueous phase was determined against numerous stresses. AEE was found to be significantly (p < 0.05) protective, i.e., against Fe2+ and Cu2+-induced linoleic acid degradation, respectively. Radiation-induced lipid oxidation studies revealed that AEE maximally works at a [lignan]/0.25 kGy ratio 400 (ratio of concentration of AEE divided by the radiation dose, i.e., 0.25 kGy) and no drug-induced lipid oxidation at all concentrations tested was found. In a time-dependent study, total antioxidant activity was maximally exhibited at 1 mg/ml. The site-specific and non-site-specific deoxyribose degradation assay exhibited a dose-dependant hydroxyl scavenging potential of AEE (0.05-500 microg/ml). The anti-lipid peroxidation ability of AEE against radiation (0.25 kGy)-induced lipid peroxidation was higher in case of neural tissue homogenate as compared to kidney homogenate [activity ratio: 0.039 (brain) < 0.24 (kidney)]. The protein protection study using bovine serum albumin was also done for two time intervals (2 h and 4 h) and significant (p < 0.05) protection was observed at 500 microg/ml (> 97%). This study implies that 3-O-beta-D-galactoside present in AEE renders radioprotection by protecting lipids, proteins in renal and neural model system against supra-lethal (0.25 kGy) gamma radiation.

Phenolics as potential antioxidant therapeutic agents: Mechanism and actions

Accumulating chemical, biochemical, clinical and epidemiological evidence supports the chemoprotective effects of phenolic antioxidants against oxidative stress-mediated disorders. The pharmacological actions of phenolic antioxidants stem mainly from their free radical scavenging and metal chelating properties as well as their effects on cell signaling pathways and on gene expression. The antioxidant capacities of phenolic compounds that are widely distributed in plant-based diets were assessed by the Trolox equivalent antioxidant capacity (TEAC), the ferric reducing antioxidant power (FRAP), the hypochlorite scavenging capacity, the deoxyribose method and the copper-phenanthroline-dependent DNA oxidation assays. Based on the TEAC, FRAP and hypochlorite scavenging data, the observed activity order was: procyanidin dimer > flavanol > flavonol > hydroxycinnamic acids > simple phenolic acids. Among the flavonol aglycones, the antioxidant propensities decrease in the order quercetin, myricetin and kaempferol. Gallic acid and rosmarinic acid were the most potent antioxidants among the simple phenolic and hydroxycinnamic acids, respectively. Ferulic acid displayed the highest inhibitory activity against deoxyribose degradation but no structure–activity relationship could be established for the activities of the phenolic compounds in the deoxyribose assay. The efficacies of the phenolic compounds differ depending on the mechanism of antioxidant action in the respective assay used, with procyanidin dimers and flavan-3-ols showing very potent activities in most of the systems tested. Compared to the physiologically active (glutathione, α-tocopherol, ergothioneine) and synthetic (Trolox, BHA, BHT) antioxidants, these compounds exhibited much higher efficacy. Plant-derived phenolics represents good sources of natural antioxidants, however, further investigation on the molecular mechanism of action of these phytochemicals is crucial to the evaluation of their potential as prophylactic agents.

Anti-oxidant activity of spermine and spermidine re-evaluated with oxidizing systems involving iron and copper ions

This study was designed to investigate the direction of redox reactions of spermine and spermidine in the presence of iron and copper. The redox activity of spermine and spermidine was assessed using a variety of methods, including their ability to: (1) reduce Fe 3+ to Fe 2+ ions; (2) protect deoxyribose from oxidation by Fe 2+–ethylene diaminetetraacetic acid, Fe 3+–ethylene diaminetetraacetic acid systems with and without H 2O 2; (3) protect DNA from damage caused by Cu 2+–H 2O 2, and Fe 2+–H 2O 2 with and without ascorbic acid; (4) inhibit H 2O 2-peroxidase-induced luminol dependent chemiluminescence; (5) scavenge diphenyl-picryl-hydrazyl radical. Spermine and spermidine at concentration 1 mM reduced 1.8 ± 0.3 and 2.5 ± 0.1 nmol of Fe 3+ ions during 20 min incubation. Both polyamines enhanced deoxyribose oxidation. The highest enhancement of 7.6-fold in deoxyribose degradation was found for combination of spermine with Fe 3+–ethylene diaminetetraacetic acid. An 10 mM spermine and spermidine decreased CuSO 4–H 2O 2–ascorbic acid- and FeSO 4–H 2O 2–ascorbic-induced DNA damage by 73 ± 6, 69 ± 4% and 90 ± 5, 53 ± 4%, respectively. They did not protect DNA from CuSO 4–H 2O 2 and FeSO 4–H 2O 2. Spermine apparently increased the CuSO 4–H 2O 2-dependent injury to DNA. Polyamines attenuated H 2O 2-peroxidase-induced luminol dependent chemiluminescence. Total light emission from specimens containing 10 mM spermine or spermidine was attenuated by 85.3 ± 1.5 and 87 ± 3.6%. During 20 min incubation 1 mM spermine or spermidine decomposed 8.1 ± 1.4 and 9.2 ± 1.8% of diphenyl-picryl-hydrazyl radical. These results demonstrate that polyamines of well known anti-oxidant properties may act as pro-oxidants and enhance oxidative damage to DNA components in the presence of free iron ions and H 2O 2.

Antioxidant potential of aerial part of Asclepias curassavica. Linn (Family-Asclepiadaceae)

Asclepias curassavica. Linn, an erect, simple (or) much branched perennial herb with a somewhat woody base, belonging to the family Asclepiadaceae. It has been reported to have multiple pharmacological effect of anti-inflammatory, cardiotonic, anticancer, anthelmintic and to treat piles and gonorrhoea. It is to be expected that several activities might be related to a possible antioxidant action from this plant. The hydro alcoholic extract of Asclepias curassavica was tested in vitro for its antioxidant activities, such as DPPH radical, nitric oxide radical, superoxide anion radical, lipid peroxidation assay, hydroxyl radical, reducing power, and total phenol content. The extract exhibited scavenging potential with <TEX>$IC_{50}$</TEX> value of <TEX>$8.7\;{\mu}g/ml,\;198.4\;{\mu}g/ml\;and\;21.7\;{\mu}g/ml$</TEX> for DPPH, nitric oxide and superoxide anion radicals. The values were found to higher than those of Vitamin-C, rutin, and curcumin, as standards. The extract showed 50% protection at the dose of <TEX>$134.2\;{\mu}g/ml\;and\;41.4\;{\mu}g/ml$</TEX> in lipid peroxidation as well as deoxyribose degradation, those values more to that of standard, vitamin E <TEX>$(IC50\;values,\;119.2\;{\mu}g/ml\;and\;32.5\;{\mu}g/ml,\;respectively)$</TEX>. The reducing power of the extract depends on the concentration and amount of extract. Since a significant amount of polyphenol could be detected by the equivalent to <TEX>$0.0495\;{\mu}g$</TEX> of pyrocatechol from 1 mg of extract. It can be concluded that hydro alcoholic extract of aerial part of Asclepias curassavica could be considered as potent antioxidant, which makes it suitable for the prevention of human disease.

Antioxidant Properties of Myrtilli Folium , Phaseoli Fructus Sine Seminibus and Drug Mixture Extracts

In vitro investigations for the antioxidant and free radical scavenging activity of Myrtilli folium-, Phaseoli fructus sine seminibus- and a drug mixture (Equiseti herba, Myrtilli folium, Phaseoli fructus sine seminibus, Urticae folium) extracts showed antioxidant (LPO inhibitory and chain-breaking antioxidant) activity and free radical (superoxide anion and hydroxyl radical) scavenging effect. The extracts inhibited lipid peroxidation induced enzymatically by adding NADPH and non-enzymatically by adding Fe2+ in brain microsomes and in brain homogenates, respectively. The extracts reduced the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), which showed chain-breaking antioxidant activity. The extracts scavenged superoxide radicals (O2-·) by inhibiting the reduction of nitro blue tetrazolium evoked by phenazine methosulphate. In addition, the extracts inhibited Fenton-reagent (Fe2+ and H2O2) induced deoxyribose degradation, therefore, it was concluded that the extracts have hydroxyl radical (OH·) scavenging property.

Antioxidant activity in Australian native sarsaparilla ( Smilax glyciphylla)

A hot water extract of the Australian native sarsaparilla Smilax glyciphylla Sm. (Smilaceae) inhibited peroxidation of phosphatidylcholine liposomes initiated by Fe 2+/ascorbate (IC 50, 10 μg/mL) and AAPH (IC 50, 33 μg/mL) in vitro. It also inhibited deoxyribose degradation and quenched chemically generated superoxide anion (IC 50, 50 μg/mL). Reactivity towards ABTS (2,2′-azinobis(3-ethylbenzothiazoline 6-sulphonate) radical cation was equivalent to 48.4 mM TROLOX, the water soluble α-tocopherol analogue. Smilax glyciphylla is a rich source of the dihydrochalcone glycyphyllin. Given the reported level of activity it is unlikely that glycyphyllin would provide direct antioxidant protection in tissues affected by oxidative stress. However, consuming Smilax glyciphylla as a tea may be sufficient to reduce oxidative damage in the gastrointestinal tract. It is also possible that glycyphyllin is metabolised and adsorbed as phloretin, a compound with known anticancer properties. These findings indicate that further studies of the chemopreventative properties of Smilax glyciphylla is warranted.