Protection against radiation clastogenecity in mouse bone marrow by Phyllanthus niruri

The effects of aqueous (PnAq) and alcoholic (PnA1 extract (50-250 mg/kg) of P. niruri on in vivo gamma radiation induced chromosome aberration and in vitro antioxidant activity (50-500 microg/ml) were studied. The antioxidant activity was studied by measuring inhibition of hydroxyl radicals generated by the fenton reaction along with pro-oxidant and iron chelating ability. PnA1 showed highly significant in vitro free radical scavenging ability when compared to DMSO above 250 microg/ml concentration. PnAq showed significant pro-oxidant activity while PnA1 was devoid of it at the tested concentrations. Exposure to gamma radiation (4 Gy) caused 29.10 % increase in the frequency of chromosomal aberrations. Administration of PnA1 (250 mg/kg) showed highly significant decrease in chromosomal aberrations compared to radiation treated group. Radioprotective potential of alcoholic extract was found to be more effective than the aqueous extract. Qualitative phytochemical investigation of PnAq and PnA1 revealed the presence of sugars, flavonoids, alkaloid, lignans, polyphenols, tannins, coumarins and saponins. Higher radioprotective effect of the alcoholic extract may be attributed to rich presence of antioxidant polyphenolic compounds.     

Antimicrobial activity and mechanism of action of Nu-3, a protonated modified nucleotide

For centuries, plants have been used in traditional medicines and there has been recent interest in the chemopreventive properties of compounds derived from plants. In the present study, we investigated the antibutyrylcholinestrasic (anti-BuChE) and antioxidant (against some free radicals) activities of extracts from Rhus pentaphyllum. Aqueous extracts were prepared from powdered R. pentaphyllum roots, leaves and seeds and characterized for the presence of tannins, flavonoids and coumarins. Seeds aqueous extract contained the highest quantities of both flavonoids and tannins (21.12% and 17.45% respectively). In the same way, seeds extracts displayed remarkable inhibition against BuChE over 95%, at 100 μg/ml and with IC₅₀ 0.74 μg/ml. In addition, compared to leaves and roots extracts, seeds aqueous extract revealed relatively strong antiradical activity towards the ABTS ^.+ (IC₅₀ = 0.25 μg/ml) and DPPH (IC₅₀ = 2.71 μg/ml) free radicals and decreased significantly the reactive oxygen species such O₂ ^.- (IC₅₀ = 2.9 μg/ml) formation evaluated by the non-enzymatic generating O₂ ^.- system (Nitroblue tetrazolium/riboflavine). These data suggest that the anti-BuChE activities mechanism of these extracts occurs through a free radical scavenging capacities. The present study indicates that extracts of Rhus pentaphyllum leaves, seeds and roots are a significant source of compounds, such as tannins, flavonoids and coumarins, with anti-BuChE and antioxidant activities, and thus may be useful for chemoprevention.     

Bioactivity-guided fractionation of Coronopus didymus: A free radical scavenging perspective

The whole plant aqueous extract of Coronopus didymus Linn. was fractionated on the basis of polarity and resulting fractions were evaluated for free radical scavenging ability. The most non-polar fraction (CDF1) was found to be more active than other fractions in scavenging DPPH, ABTS(-), nitric oxide and hydroxyl radicals in steady-state conditions. Stop-flow spectrometric studies showed 58.13% inhibition of 100 microM DPPH at a concentration of 150 microg/ml of CDF1 in 1000 s and 32.31% scavenging of 960 microM ABTS(-) at a concentration of 300 microg/ml of CDF1 in 100 s. The reaction of CDF1 with hydroxyl radicals produced by pulse radiolysis showed a transient spectrum with absorption peaks at 320, 390 and 400 nm, indicating the presence of flavonoids/related components. Competition kinetics with potassium thiocyanate against scavenging of hydroxyl radicals showed a reactivity of 0.1326 against thiocyanate. CDF1 also protected against Fenton reagent-induced calf thymus DNA damage at a concentration of 400 mg/ml indicating it to be the most potent fraction.     

Protection of coumarins against linoleic acid hydroperoxide-induced cytotoxicity

Coumarins comprise a group of natural phenolic compounds found in a variety of plant sources. Protective effects of coumarins against cytotoxicity induced by linoleic acid hydroperoxide were examined in cultured human umbilical vein endothelial cells. When the cells were incubated in medium supplemented with linoleic acid hydroperoxide and coumarins, esculetin (6,7-dihydroxycoumarin) and 4-methylesculetin protected cells from injury by linoleic acid hydroperoxide. Fraxetin and caffeic acid showed weak, but significant, protection. Esculin as well as esculetin and 4-methylesculetin were effective for protecting cells against linoleic acid hydroperoxide-induced cytotoxicity in the case of pretreatment for 24 h, however fraxetin and caffeic acid showed no protection. Since esculetin was detected after 24 h treatment with esculin, a sugar moiety in the esculin molecule appears to be hydrolyzed during pretreatment. Coumarins such as umbelliferone containing only one hydroxyl group showed no protective effect in pretreatment or concurrent treatment. Esculetin and 4-methylesculetin provided synergistic protection against cytotoxicity induced by linoleic acid hydroperoxide with alpha-tocopherol. Furthermore, the radical-scavenging ability of coumarins was examined in electron spin resonance spectrometry. Esucletin, 4-methylesculetin, fraxetin, and caffeic acid showed the quenching effect on the 1,1-diphenyl-2-picrylhydrazyl radical. These results indicate that the presence of an ortho catechol moiety in the coumarin molecules plays an important role in the protective activities against linoleic acid hydroperoixde-induced cytotoxicity.     

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.     

Novel antiviral characteristics of nanosized copper(I) iodide particles showing inactivation activity against 2009 pandemic H1N1 influenza virus

We investigated the antiviral activity of nanosized copper(I) iodide (CuI) particles having an average size of 160 nm. CuI particles showed aqueous stability and generated hydroxyl radicals, which were probably derived from monovalent copper (Cu(+)). We confirmed that CuI particles showed antiviral activity against an influenza A virus of swine origin (pandemic [H1N1] 2009) by plaque titration assay. The virus titer decreased in a dose-dependent manner upon incubation with CuI particles, with the 50% effective concentration being approximately 17 μg/ml after exposure for 60 min. SDS-PAGE analysis confirmed the inactivation of the virus due to the degradation of viral proteins such as hemagglutinin and neuraminidase by CuI. Electron spin resonance (ESR) spectroscopy revealed that CuI generates hydroxyl radicals in aqueous solution, and radical production was found to be blocked by the radical scavenger N-acetylcysteine. Taken together, these findings indicate that CuI particles exert antiviral activity by generating hydroxyl radicals. Thus, CuI may be a useful material for protecting against viral attacks and may be suitable for applications such as filters, face masks, protective clothing, and kitchen cloths.     

Site-activity relationship of nitroxide radical's antioxidative effect

A relatively new strategy in preventing oxidative damage employs cyclic nitroxides. These stable radicals have been widely used as biophysical probes, spin labels, and are currently tested as contrast agents for nuclear magnetic resonance imaging. Nitroxides were found to protect cells, organs, and whole animals against diverse oxidative insults. The present study concentrated on comparing the antioxidative activity of nitroxides against oxidative damage, initiated either in the lipid or aqueous phase, to egg phosphatidylcholine acyl chains (13.4% polyunsaturated fatty acids) in small unilamellar vesicles. We determined the lipophilicity and liposome-membrane/aqueous-medium partition coefficient for several nitroxides and compared their specific protective effects. The aim was to study the relation between nitroxides' concentration, location in the lipid bilayer, and their protection against oxidative damage. Both 6-membered- and 5-membered-ring nitroxides were studied for: (i) partitioning between the lipid bilayer and the aqueous phase (nitroxides were quantified using EPR spectroscopy); (ii) the intrabilayer distribution, using three different fluorescent probes of known location of their fluorophors in the lipid bilayer; and (iii) the specific antioxidative effect (protection per concentration) against radicals formed in a liposomal dispersion. The radicals were generated using the thermolabile, radical-generating compounds 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) in the aqueous phase, and 2,2'-azobis (2,4-dimethyl-valeronitrile) (AMVN) in the lipid phase. The results show that nitroxides react, in a concentration-dependent manner, with deleterious species at their formation sites, both in the aqueous and the lipid phase, and that their specific protective effects for the lipophilic target, the lipid bilayer, are similar for both the lipophilic and the hydrophilic nitroxides.     

Inhibition of radiation-induced lipid peroxidation by tetrahydrocurcumin: possible mechanisms by pulse radiolysis

The antioxidant property of tetrahydrocurcumin (THC), a reduced derivative of curcumin, was examined by its ability to inhibit radiation-induced lipid peroxidation in rat liver microsomes and compared with curcumin. The lipid peroxidation caused by irradiation of N2O-purged and aerated buffered aqueous solutions was found to be inhibited by THC in a dose- and concentration-dependent manner. In order to understand the actual reaction mechanisms involved in the inhibition process, pulse radiolysis investigation of THC with radiolytically produced radicals like hydroxyl, model peroxyl radicals, and azide radicals were done and the transients were detected by kinetic spectrophotometry. The reaction of THC with hydroxyl and azide radicals gave rise to transient absorption in the region 200-400 nm with two peaks at 310 nm and 390 nm. From the spectral properties and kinetics of these radicals, a suitable mechanism is discussed to explain the antioxidant actions of THC.     

Ability of melanins to protect against the radiolysis of thymine and thymidine

Individuals with black skin rarely get skin cancer, and melanomas, tumors arising from pigmented cells, are generally resistant to radiation therapy. The role of melanin in these two phenomena has not been defined, but oxygen-radical species have been implicated in both effects. These studies were undertaken to determine the ability of various melanins to compete for ionizing radiation-produced radicals which destroy nucleic acid bases. The ability of Sigma eumelanin (S-eumelanin) to protect against the radiolysis of thymidine in buffered solutions was compared to the protective ability of seven amino acids, including melanin precursors; bovine serum albumin, as a model protein; ficoll, as a model polysaccharide; and DNA. Both proteins and polysaccharides are known to scavenge hydroxyl radicals in cells. The concentration of thymidine after exposure to gamma radiation was determined by High Performance Liquid Chromatography (HPLC) analysis after removal of insoluble melanin by acid precipitation. S-eumelanin was more effective at competing with thymidine for free radicals than bovine serum albumin, Ficoll, or DNA, but less effective than certain of the small molecules. Several of the above compounds were also examined for ability to protect against thymine radiolysis. In addition, melanins from other sources were compared to S-eumelanin. Of these, enzymatically synthesized phaeomelanin was the most effective. The results indicate that melanins can compete for base- and nucleoside-damaging free radicals more effectively than other cellular macromolecules. Of the small molecules, the phenolic compounds had the greatest scavenging ability. In vivo, melanins are found in melanosomes bound to protein. Therefore, the relevance of these findings to the photo- and radiobiology of melanins in vivo has yet to be determined.     

Antiradical activity of complex copper compounds (II) on coumarin ligand base]

The antioxidant capacity of copper chelates with coumarins has been studied by the method of iron-induced chemiluminescence. All substrates studied were potent antioxidants, comparable to butylated hydroxytoluene. The mechanism of the antioxidant action of these copper-coumarin chelates was similar to that of Cu-Mn-superoxide dismutase, with a coumarin part of the complex being involved as a free radicals trap.     

Synthesis and antifungal activity of coumarins and angular furanocoumarins.

Angelicin, a naturally occurring furanocoumarin, that showed antifungal activity, was considered as a lead structure for a group of synthetic coumarins. Antifungal activities of the synthesized coumarins and angelicin derivatives were reported against Candida albicans, Cryptococcus neoformans, Saccharomyces cerevisiae and Aspergillus niger. Human cell line cytotoxicity of several coumarins was evaluated against KB cells. Angelicin and several potent antifungals showed to be non-toxic in this assay.     

Free radical damage to proteins: the influence of the relative localization of radical generation, antioxidants, and target proteins

Free radicals were generated at known rates in the aqueous phase (by means of 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) and in a membranous (lipid) phase (by means of 2,2'-azobis (2,4-dimethylvaleronitrile [AMVN]). A soluble protein (bovine serum albumin: BSA), and membranes of lysed mitochondria containing radioactively labeled monoamine oxidase (MAO), were exposed to the resultant radical fluxes. Antioxidants were added to the system, either in the aqueous phase (Trolox) or in a liposomal membrane phase (alpha-tocopherol). Protein damage was assessed as tryptophan oxidation and conformational changes in tryptophan fluorescence of the soluble protein, BSA, and as fragmentation of both BSA and monoamine oxidase. Radicals generated in the aqueous phase, by AAPH, were effective in damaging BSA and MAO. Radicals generated within the liposome membrane phase (by AMVN) were less effective against BSA than those deriving from AAPH. Liposomal AMVN radicals could damage MAO, present in a separate membranous phase, though again, less effectively than could AAPH-derived radicals. BSA could be protected by Trolox, the aqueous soluble antioxidant, but hardly by tocopherol itself. Damage to MAO was limited by Trolox, and also by the hydrophobic antioxidant, tocopherol. Damaging reactions due to radicals generated in a membrane phase were significantly accelerated when the membrane was peroxidizable (soybean phosphatidylcholine) rather than nonperoxidizable (saturated dimyristoyl phosphatidylcholine). Thus lipid radicals also played some role in protein damage in these systems. BSA was attacked similarly in the presence or absence of liposomes by AAPH. Correspondingly, BSA could inhibit the peroxidation of liposomes induced by AAPH and less efficiently that induced by AMVN.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protective effect of Hemidesmus indicus R.Br. root extract against cisplatin-induced cytogenetic damage in mouse bone marrow cells

The aqueous extract of Hemidesmus indicus roots was investigated for its in vivo antigenotoxic effect against cisplatin-induced cytogenetic damage. Swiss albino mice were administered with various doses of the extract either singly (50, 100 and 200 mg/kg body weight) or as split doses (10, 20 and 40 mg/kg bw/day) for five consecutive days by oral gavage. As endpoints, chromosome aberrations, micronuclei in polychromatic erythrocytes, mitotic index and PCE/NCE ratio were estimated. The extract protected the bone marrow cells from cisplatin-induced genotoxicity in an inverse dose-dependent manner. However, the extract was cytotoxic at all doses. But, under split dose regime it conferred a higher level of genoprotection and was not cytotoxic at the lower two doses. The presence of saponins, tannins, phenols, terpenoids, flavonoids and coumarins in the crude extract could explain these effects.     

蛹虫草MF27高抗氧化活性提取物筛选及保肝作用研究

本研究对一株优质蛹虫草菌株MF27不同提取物进行体外抗氧化活性比较,筛选得到高抗氧化活性提取物,并进一步探究该提取物对CCl₄诱导的小鼠肝损伤的修复作用。以DPPH自由基和羟自由基的清除率为抗氧化评价指标,从菌丝体发酵液、菌丝体水提物/醇提物、以及子实体水提物/醇提物中筛选菌株MF27的高抗氧化活性提取物;以CCl₄致小鼠急性肝损伤为模型,通过检测血清生化指标、肝功指标的变化,来评价该高活性提取物的体内抗氧化保肝效果。体外抗氧化实验结果表明,MF27的不同提取物均具有较好的体外抗氧化活性,但对清除DPPH和OH自由基能力最好的提取物是子实体水提物,其对DPPH自由基的半数有效浓度（EC₅₀）为0.096mg/mL,对羟自由基的半数有效浓度（EC₅₀）为0.196mg/mL,当在1mg/mL 时对DPPH自由基的清除率为94.94%,对羟自由基的清除率为70.17%;体内抗氧化保肝结果显示,给药组（子实体水提物）相比模型组而言,小鼠血清中ALT、AST以及肝脏中MDA水平极显著降低（P<0.01）、SOD水平极显著升高（P<0.01）,表明子实体水提物能有效改善氧化性肝损伤,同时与阳性对照（联苯双酯）对比,给药组在肝脏指数上表现出相当的作用（P>0.05）。本研究表明菌株MF27的最有效抗氧化活性提取物是子实体水提物,它对体内氧化性肝损伤有一定的修复能力,揭示MF27子实体水提物具有成为抗氧化性肝损伤功能产品的潜力。     

Computer-assisted, high-performance liquid chromatography with mass spectrometric detection for the analysis of coumarins in Peucedanum palustre and Angelica archangelica

A reversed-phase HPLC method with atmospheric pressure chemical ionisation MS detection has been developed for the separation and identification of coumarins in plants of Peucedanum palustre L. (Moench) and Angelica archangelica (L.) var. archangelica. The Turbo Method Development program was utilised to optimise the mobile phase with two organic solvents (acetonitrile and methanol) and two aqueous solutions (1.0% formic acid and 10 mM ammonium acetate). Optimisation of the solvent gradients for the method was performed with the aid of the DryLab program. Analyses were carried out using a Phenomenex Prodigy RP C18 column. Fifty-two peaks (14 of which were associated with coumarins) were separated in 30 min from extracts of P. palustre, and 48 peaks (15 associated with coumarins) from extracts of A. archangelica. A total of 21 different coumarin-type compounds were identified in the aerial and the underground parts of the title plants. Isopimpinellin and pimpinellin were found for the first time in P. palustre and were identified by comparison of retention times and MS data obtained following the analysis of pure standards. This is the first report of the coumarin composition of the umbels of P. palustre.     

Ultrasound-assisted aqueous extraction of total flavonoids and hydroxytyrosol from olive leaves optimized by response surface methodology

Abstract

Olive leaves were often extracted with methanol or ethanol at different proportions. In this study, ultrasound-assisted aqueous extraction was adopted for olive leaf extraction. The yields of total flavonoids (TF) and hydroxytyrosol (HT) were optimized by central composite experimental design. Two second-order polynomial equations were established to quantify the relationship between the responses and the processing parameters. Under the optimal condition of extracting at 60?°C for 60?min with the solvent-to-material ratio of 40, TF and HT amounted to 57.31?±?0.35 and 1.80?±?0.02?mg/g dry leaves (DL), respectively. The scavenging rate of all extracts against α, α-diphenyl-β-picrylhydrazyl (DPPH) and hydroxyl free radicals was screened. The integrated scores, representing both active ingredients and antioxidant capacity of the extracts, were calculated by principle component analysis (PCA). The optimal extract gained the highest score in PCA. In addition, compared to the extracts from 80% methanol to 44% ethanol, the ultrasound-assisted aqueous extract was richer in TF, HT, and polyphenols, while it also presented stronger ferric reducing antioxidant power (FRAP), but poorer strength to quench hydroxyl radicals. The study indicated that the aqueous extract of olive leaves may present broad potential opportunities in health-care sector.     

Comparison of the radical trapping ability of PBN, S-PPBN and NXY-059

The nitrones alpha-phenyl-N-tert-butyl nitrone (PBN), sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) and disodium 2,4-disulfophenyl-N-tert-butyl nitrone (NXY-059) are neuroprotective in a variety of rodent models. The objective of the current studies was to compare the ability of PBN, S-PBN, and NXY-059 to form radical adducts and to prevent salicylate oxidation in an aqueous system. For the electron spin resonance (ESR) studies, hydroxyl radicals were generated with ultraviolet (UV) light and hydrogen peroxide. Secondary radicals were then produced by the addition of methanol, ethanol, isopropanol, dimethylsulfoxide, tetrahydrofuran or 1,4-dioxane. In addition, competition spin trapping studies were performed using PBN-alpha-(13) C and either S-PBN or NXY-059. In the salicylate studies, PBN, S-PBN and NXY-059 were compared to a variety of other antioxidants and reference compounds (cysteine, glutathione, ascorbate, uric acid, Tempo, Trolox, and Tirilizad) for their ability to prevent 2,3- and 2,5-dihydroxybenzoic acid formation induced by hydroxyl radical generating systems. All 3 nitrones trapped carbon- and oxygen-centered radicals to produce ESR-detectable radical adducts. Each nitrone also prevented salicylate oxidation, with PBN being the most effective. The ability of these 3 nitrones to prevent salicylate oxidation resembled that of most of the other compounds tested.     

Reactions of arylamine and aminophenol derivatives, and riboflavin with organic radicals

Based on product yield data on radiolysis of hexane, ethanol and 3 M aqueous ethylene glycol solutions, the ability of a number of arylamine, aminophenol and quinonimine derivatives to affect processes involving peroxyl, alkyl or alpha-hydroxyalkyl radicals was assessed. It has been shown that the introduction of a hydroxyl group into aromatic amine structure enhances its antioxidant performance and makes it significantly more reactive with respect to carbon-centered organic radicals. Replacement of the hydrogen atom of a hydroxyl group by a methyl group decreases the anti-radical activity of aminophenols drastically. Compounds containing (or capable of forming) a quinonimine moiety interact with alkyl or alpha-hydroxyalkyl radicals most effectively, suppressing recombination and fragmentation reactions of the latter. In the sequence: aromatic amines--aminophenols--quinonimines, a trend towards enhancement of the ability of the compounds studied to react with carbon-centered radicals was noted. Also, this study presents for the first time evidence of riboflavin reactivity with respect to organic radicals.     

ESR and optical absorption evidence for free radical involvement in the photosensitizing action of furocoumarin derivatives and for their singlet oxygen production.

Frozen aqueous solutions of thymine and its derivatives were irradiated with visible light (lambda greater than 320 nm) in the presence of various furocoumarins. ESR analysis revealed the induction of hydrogen adduct free radicals at C-6 position of thymine, only with those furocoumarin derivatives which show a skin-photosensitizing ability. It has been shown, moreover, that the photocycloaddition of psoralen to thymine, which is responsible for the biological effects of this dye, is inhibited when the induction of free radicals in thymine moiety has been prevented by electron scavengers. It is suggested that the free radicals observed could be involved in the biological photosensitization. The mechanism of free radical generation and singlet oxygen production by furoccoumarins were also investigated.     

Reactions of Arylamine and Aminophenol Derivatives,and Riboflavin with Organic Radicals

Based on product yield data on radiolysis of hexane, ethanol and 3 M aqueous ethylene glycol solutions, the ability of a number of arylamine, aminophenol and quinonimine derivatives to affect processes involving peroxyl, alkyl or α-hydroxyalkyl radicals was assessed. It has been shown that the introduction of a hydroxyl group into aromatic amine structure enhances its antioxidant performance and makes it significantly more reactive with respect to carbon-centered organic radicals. Replacement of the hydrogen atom of a hydroxyl group by a methyl group decreases the anti-radical activity of aminophenols drastically. Compounds containing (or capable of forming) a quinonimine moiety interact with alkyl or α-hydroxyalkyl radicals most effectively, suppressing recombination and fragmentation reactions of the latter. In the sequence: aromatic amines--aminophenols--quinonimines, a trend towards enhancement of the ability of the compounds studied to react with carbon-centered radicals was noted. Also, this study presents for the first time evidence of riboflavin reactivity with respect to organic radicals.