Effects on free radicals and inhibition of alpha-amylase of Cardamine battagliae (Cruciferae), an apoendemic Calabrian (southern Italy) plant

The present study showed for the first time the biological properties of different fractions from Cardamine battagliae Cesca & Peruzzi, an apoendemic Calabrian (southern Italy) plant that belongs to the Cruciferae family. The antioxidant activities of the different fractions of C. battagliae were carried out using two different in vitro assays (beta-carotene bleaching test and lipid peroxidation of liposomes assay) while radical scavenging activity was carried out using DPPH test. AcOEt fraction showed the highest activity on DPPH inhibition (IC50 of 0.162 mg mL(-1)) while dichloromethane fraction showed the highest activity on beta-carotene bleaching (IC(50) of 0.004 mg mL(-1)). The assay for alpha-amylase inhibition showed that n-hexane fraction showed the highest activity with an IC50 of 0.055 mg mL(-1).     

Antioxidant and cytotoxic activities of methanolic extract and fractions from Senecio gibbosus subsp. gibbosus (GUSS) DC

The aim of this study was to evaluate the in vitro antioxidant and cytotoxic activities of the methanolic extract and fractions of Senecio gibbosus subsp. gibbosus aerial parts. The antioxidant activity was assessed by means of two different tests: (1) bleaching of the stable 2,2-diphenyl-1-picrylhydrazil (DPPH) radical; and (2) lipid peroxidation of liposomes which were prepared from bovine brain extract. In both tests used methanolic extract and AcOEt fraction showed a significant antioxidant effect. The cytotoxic activity of the methanolic extract and fractions was carried out using the SRB assay. The methanolic extract demonstrated a good cytotoxic activity against human breast cancer cell line (MCF-7) and human prostate cancer cell line (LNCaP). Dichloromethane and AcOEt fractions showed the greatest cytotoxic activity, particularly on LNCaP cell line.     

番茄红素对镉诱导睾丸损伤大鼠抗氧化酶活性及生殖激素水平的影响

目的观察番茄红素对镉诱导睾丸损伤大鼠抗氧化酶活性及生殖激素水平的影响。方法将28只雄性SD大鼠随机分为4组,每组7只,分别为空白对照组、5 mg/L镉组、5 mg/L镉+10 mg/kg番茄红素组、5 mg/L镉+20 mg/kg番茄红素组,给药1周后处死,测定睾丸组织超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)活性及血清促黄体生成素(LH)、睾酮(T)水平。结果镉组大鼠体质量、睾丸质量、睾丸组织SOD、GSH-Px活性及血清T水平均显著低于NC组(P0.01),睾丸组织MDA含量和血清LH水平则显著高于后者(P0.01);番茄红素可缓解染镉大鼠体质量和睾丸质量的减轻,并回调抗氧化酶活性和生殖激素水平,且高剂量组效果更为显著。结论番茄红素对染镉大鼠的睾丸损伤具有剂量依赖性的改善作用,可能与清除氧自由基和抗脂质过氧化有关。     

Antioxidant activity assay based on the inhibition of oxidation and photobleaching of l-cysteine-capped CdTe quantum dots

Quantum dots (QDs) have recently been the focus of attention of many investigators for development of diagnostic tools in many research areas. In this work, we established a new QD-based assay to evaluate the antioxidant/polyphenolic activity. This assay is based on measurement of the inhibitory effect of the antioxidant/polyphenolic compounds on the UV-induced bleaching of CdTe QDs with l-cysteine capping. QDs exhibited excellent photostability without any UV exposure, while they bleached rapidly under UV irradiation. Generation of reactive oxygen species (ROS) under UV irradiation is probably the main cause of the photobleaching of QDs. By comparing the photostability of QDs in buffer solution in the absence and presence of sodium azide, as a known (1)O(2) quencher, the involvement of (1)O(2) in photobleaching of QDs was confirmed. The photobleaching effect induced by ROS could be reduced in the presence of antioxidant/polyphenolic compounds. We tested several antioxidant/polyphenolic compounds as well as known antioxidants such as trolox and 4 different types of tea. The results obtained by the QD-based assay revealed a very good correlation with the data acquired by Folin-Ciocalteu assay. Furthermore, a deeper understanding of the mechanism and the solution for photobleaching of QDs under UV irradiation might be very meaningful in promoting their clinical applications.     

Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching.     

Absolute rate constants for the quenching of reactive excited states by melanin and related 5,6-dihydroxyindole metabolites: implications for their antioxidant activity

The triplet-excited state of benzophenone and the singlet-excited state of 2,3-diazabicyclo[2.2.2]oct-2-ene (Fluorazophore-P) have been employed as kinetic probes to obtain information on the antioxidant activity of the skin and eye pigment melanin and its biogenetic precursors 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). The excited states were generated by the laser-flash photolysis technique and their reaction kinetics was examined by time-resolved transient absorption or fluorescence spectroscopy, respectively. The reaction between triplet benzophenone and DHI produced with unit efficiency the corresponding 6O-centered semiquinone radical, which was characterized by its characteristic transient absorption. The quenching rate constants for DHI (3.1-8.4 x 10(9) M-1 s-1) and DHICA (3.3-5.5 x 10(9) M-1 s-1) were near the diffusion-controlled limit, indicating excellent antioxidant properties. Kinetic solvent effects were observed. The reactivity of synthetic melanin, assessed through the quenching rate constant of Fluorazophore-P and normalized to the number of monomer units, was more than one order of magnitude lower (2.7 x 10(8) M-1 s-1) than that of its precursors. The trend of the quenching rate constants, i.e. DHI > DHICA approximately alpha-tocopherol > melanin, along with the preferential solubility of DHICA in aqueous environments, serves to account for several experimental results from biochemical studies on the inhibition of lipid peroxidation by these natural antioxidants.     

The influence of melanins on the photoperoxidation of lipids

The influence of synthetic Dopa-melanin, natural-A, AB-melanin and pheomelanin has been studied for the following processes: (1) microsomal and liposomal lipid peroxidation induced by illumination with UV- and visible light; (2) interaction of melanin with the superoxide anion; and (3) chemiluminescence intensity of phospholipids in the presence and absence of melanins. It has been shown that (a) melanins can function as a scavenger of the superoxide anion radical O2-. (pseudo-superoxide dismutase) and (b) melanins protect microsomes and liposomes against lipid peroxidation which is due to the absorption of light energy (filter effect). Our data show that in the presence of melanins lipid peroxidation is significantly lower in comparison with the phospholipids incubated in the absence of melanins (except pheomelanin). The level of photoperoxidation of lipids was studied by means of the chemiluminescence method and by measurement of the malondialdehyde product. The results obtained by both methods indicate that melanin can effectively influence the process of lipid peroxidation. Mechanisms involved in the physical (optical screening) and photochemical reactions are proposed.     

Transient products in the photoreduction of benzophenone derivatives in poly(ethylene-vinyl alcohol) film

The formation, stability, and reactivity with oxygen of the so-called light-absorbing transient (LAT) photoproducts formed on photoreduction of benzophenone and several benzophenone derivatives in poly(ethylene-vinyl alcohol) (EVOH) films were investigated. The maximum total yield of LAT photoproducts on photoreduction of benzophenone was estimated to be approximately 50%, which was found to comprise around 75% of the para-LAT isomer with the remainder being attributed to the ortho-LAT isomer. The concentrations of these LAT isomers were found to decay over a period of weeks at room temperature in the absence of oxygen, with the decay of the para-LAT isomer being substantially slower than the ortho-LAT isomer. Furthermore, the decay rate of the para-LAT isomer was found to increase markedly in the presence of oxygen. Mechanisms for the decay of the LAT isomers that are consistent with available data are postulated. The presence of alkyl, alkoxy, or aryloxy moieties on the phenyl rings of benzophenone appears to have little effect on the efficiency of formation, stability, and reactivity with oxygen of the LAT photoproducts in EVOH films, for the benzophenone derivatives studied in this work.     

Ruta chalepensis L. (Rutaceae) leaf extract: chemical composition,antioxidant and hypoglicaemic activities

Ruta chalepensis L. (Rutaceae) leaf extract was investigated for its chemical profile and antioxidant and hypoglycaemic properties. The antioxidant effects were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene bleaching, and metal chelating activity assays. The carbohydrate-hydrolysing enzymes inhibition assay was used to test the hypoglycaemic potential. R. chalepensis showed a high content of hesperidin and rutin with values of 591.9 and 266.7 mg/g dry extract, respectively. The extract exhibited a promising protection of lipid peroxidation (IC₅₀ value of 16.9 μg/mL) and inhibited both α-amylase and α-glucosidase enzymes in a concentration-dependent manner. The highest activity was found against α-amylase (IC₅₀ value of 69.0 μg/mL). The obtained results support the use of R. chalepensis leaves as healthy food ingredients.     

UV-B-induced formation of reactive oxygen species and oxidative damage of the cyanobacterium Anabaena sp.: protective effects of ascorbic acid and N-acetyl-L-cysteine

Reactive oxygen species (ROS) are involved in the oxidative damage of the cyanobacterium Anabaena sp. caused by UV-B (280-315 nm) radiation. UV-B-induced overproduction of ROS as well as the oxidative stress was detected in vivo by using the ROS-sensitive probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). Thiobarbituric acid reactive substances (TBARS) and fluorometric analysis of DNA unwinding (FADU) methods were adapted to measure lipid peroxidation and DNA strand breaks in Anabaena sp. Moderate UV-B radiation causes an increase of ROS production, enhanced lipid peroxidation and DNA strand breaks, yielding a significantly decreased survival. In contrast, the supplementation of UV-A in our work only showed a significant increase in total ROS levels and DNA strand breaks while no significant effect on lipid peroxidation, chlorophyll bleaching or survival was observed. The presence of ascorbic acid and N-acetyl-L-cysteine (NAC) reversed the oxidative stress and protected the organisms from chlorophyll bleaching and the damage of photosynthetic apparatus induced by UV-B significantly, resulting in a considerably higher survival rate. Ascorbic acid also exhibited a significant protective effect on lipid peroxidation and DNA strand breaks while NAC did not show a substantial effect. These results suggest that ascorbic acid exhibited significantly higher protective efficiency with respect to DNA strand breaks and survival than NAC while NAC appears to be especially effective in defending the photosynthetic apparatus from oxidative damage.     

Solubilization of fullerene C60 in micellar solutions of different solubilizers

Fullerene (C₆₀), the third carbon allotrope, is a classical engineered material with the potential application in biomedicine. However, extremely high hydrophobicity of fullerene hampers its direct biomedical evaluation and application. In this work, we investigated the solubilization of fullerene using 9 different solubility enhancers: Tween 20, Tween 60, Tween 80, Triton X-100, PVP, polyoxyethylene (10) lauryl ether, n-dodecyl trimethylammonium chloride, myristyl trimethylammonium bromide and sodium dodecyl sulphate and evaluated its antioxidant activity in biorelevant media. The presence of C₆₀ entrapped in surfactant micelles was confirmed by UV/VIS spectrometry. The efficacy of each modifier was evaluated by chemometric analysis using experimental data for investigating the relationship between solubilization and particle size distribution. Hierarchical clustering and principal component analysis was applied and showed that non-ionic surfactants provide better solubilization efficacy (>85%). A correlation was established (r = 0.975) between the degree of solubilization and the surfactant structure. This correlation may be used for prediction of C₆₀ solubilization with non-tested solubility modifiers. Since the main potential biomedical applications of fullerene are based on its free radical quenching ability, we tested the antioxidant potential of fullerene micellar solutions. Lipid peroxidation tests showed that the micellar solutions of fullerene with Triton and polyoxyethylene lauryl ether kept high radical scavenging activity, comparable to that of aqueous suspension of fullerene and BHT. The results of this work provide a platform for further solubilization and testing of pristine fullerene and its hydrophobic derivatives in a biological benign environment.     

Antioxidant activity of propofol and related monomeric and dimeric compounds

This study was carried out to investigate the antioxidant activity of propofol (2,6-diisopropylphenol) and its related compounds, butylated hydroxyanisole (BHA), 2,6-dimethylphenol, 2,6-di-t-butylphenol, and their dimeric compounds. The degree of antioxidant activity was evaluated based on the degree of peroxidation induced with Fe-ascorbic acid in egg phosphatidylcholine through the determination of thiobarbituric acid-reactive substances (TBARS) formed during peroxidation. Their antioxidant activities were in the order of dipropofol>di(2,6-di-t-butylphenol)>diBHA>di(2,6-dimethylphenol). Dipropofol, a dimeric compound of propofol, showed the highest antioxidant activities. Dimeric compounds had higher activities than monomeric compounds, and the 1,1-diphenyl-p-picryhydrazyl-trapping ability of dimeric compounds was also greater than those of monomeric compounds (4-10-fold). These results suggest that dimeric phenols may increase their antioxidant activities along with increments in the conjugation system and play a inhibitory role in the propagation of free radical chain reactions.     

UV-induced changes in antioxidant capacities of selected carotenoids toward lecithin in aqueous solution

Antioxidant action of four selected carotenoids (two carotenes, β-carotene and lycopene, and two xanthophylls, lutein and neoxanthin) on UV-induced lecithin lipid peroxidation in aqueous solution has been studied by thiobarbituric acid (TBA) test. TBA test is based on absorbance measurements of complex formed between malondialdehyde, secondary product of lipid peroxidation and thiobarbituric acid, at 532 nm. The antioxidant capacities of investigated carotenoids appeared to be strongly affected by UV-action. High energy input of the involved UV-photons plays major governing role, though a certain impact of the carotenoid structures cannot be neglected. The results suggest a minor remained contribution of selected carotenoids to prevention of lecithin peroxidation in the studied system as a result of UV-irradiation.     

A novel isopimarane diterpenoid with acetylcholinesterase inhibitory activity from Nepeta sorgerae, an endemic species to the Nemrut Mountain

From the dichloromethane extract of Nepeta sorgerae, the isolation and structure elucidation are now reported of a new isopimarane diterpenoid, named sorgerolone, and two known triterpenoids, oleanolic acid and ursolic acid. Antioxidant activity of the extracts and the isolated terpenoids was determined by the DPPH free radical scavenging and lipid peroxidation inhibition (beta-carotene bleaching) methods. Anticholinesterase activity of the extracts and isolates was investigated by Ellman's method against AChE and BChE enzymes. Although the antioxidant activity results were low, the AChE enzyme inhibition of the extracts and terpenoids was very promising.     

RESPONSE OF THE WILD-TYPE and HIGH LIGHT-TOLERANT MUTANT OF Anacystis nidulans AGAINST PHOTOOXIDATIVE DAMAGE: DIFFERENTIAL MECHANISM OF HIGH LIGHT TOLERANCE

Abstract— A high light-tolerant mutant of Anacystis was able to tolerate about three-fold higher light energy irradiance (30 W m^-2) than the wild type (10 W m^-2). The loss of sulfhydryl content and rate of lipid peroxidation in the wild-type cells is lower than in the mutant cells at high light irradiance. This phenomenon in the wild type is probably due to high light-induced severe photoinhibitory conditions resulting in a decreased rate of O₂ evolution. Results on the bleaching of the N, N '-dimethyl- p -nitrosoaniline at high light irradiance show a higher rate of bleaching in the wild-type than in the mutant cells. Further, results on the rate of N, N '-dimethyl- p -nitrosoani)ine bleaching in the presence of radical scavengers like sodium azide, histidine and sodium formate (10 m M , each) suggest that singlet oxygen is the predominant oxygen species produced in both the wild-type and mutant cells under high light. However, a similar quenching effect of formate in the mutant cells is indicative of increased formation of hydroxyl radicals. This observation is further corroborated by higher rate of lipid peroxidation. In addition to this, the superoxide dismutase activity is higher in the mutant (1.2 unit) than in the wild type. Taken together, these results suggest that the cells of the high light-tolerant mutant have an efficient intracellular mechanism to transform the free oxygen radicals.     

Excitation of chemiluminescence in the reaction of benzophenone-O-oxide with diphenyldiazomethane. Quantum-induced decomposition of diphenyldiazomethane

The excitation yield (⌽⁺) of triplet benzophenone in the chemiluminescence reaction of thermal decomposition of diphenyldiazomethane (Ph₂CN₂) was measured. Triplet benzophenone was produced by the reaction of benzophenone-O-oxide with Ph₂CN₂ in a MeCN solution. The ⌽⁺ value is equal to 0.05 and temperature-independent. Analysis of the dependences of the observed rate constant of chemiluminescence decay on the concentration of Ph₂CN₂ both in the presence and absence of a luminescence activator suggests the quantum-induced decomposition of diazomethane in the reaction with triplet benzophenone. The rate constant of the reaction of triplet benzophenone with Ph₂CN₂ was estimated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1097–1101, June, 1999.     

Pothomorphe umbellata extract prevents alpha-tocopherol depletion after UV-irradiation

In this work we evaluated the influence of topical application of P. umbellata root extract gel, containing 0.1% of 4-nerolidylcathecol, on the antioxidant network in UV-induced oxidative damage in hairless mouse skin. The UV-irradiation had no influence on ascorbic acid levels or on the antioxidant enzyme (superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase) activities, but topical P. umbellata treatment protected alpha-tocopherol from being depleted after UV-irradiation. alpha-Tocopherol concentration decreased significantly (approximately 40%, P < 0.01) in the irradiated control groups, whereas in the P. umbellata-treated group, alpha-tocopherol was totally preserved (approximately 100%, P > 0.05). These data demonstrate that P. umbellata may be successfully used as a topical photoprotective agent.     

Antioxidant activity of olive phenols: mechanistic investigation and characterization of oxidation products by mass spectrometry

In this work, the antioxidant activity of olive phenols is first characterized by their stoichiometries n(tot)(number of radicals trapped per antioxidant molecule) and their rate constants for the first H-atom abstraction k(1) by the stable radical DPPH. It appears that oleuropein, hydroxytyrosol and caffeic acid have the largest k(1) values, whereas dihydrocaffeic acid, an intestinal metabolite of caffeic acid, is the best antioxidant in terms of n(tot). For phenols with a catechol moiety n(tot) is higher than two, implying an antioxidant effect of their primarily formed oxidation products. A HPLC-MS analysis of the main products formed in the AAPH-induced oxidation of olive phenols reveals the presence of dimers and trimers. With hydroxytyrosol and dihydrocaffeic acid, oligomerization can take place with the addition of water molecules.The antioxidant activity of olive phenols is then evaluated by their ability to inhibit the AAPH-induced peroxidation of linoleic acid in SDS micelles. It is shown that olive phenols and quercetin act as retardants rather than chain breakers like alpha-tocopherol. From a detailed mechanistic investigation, it appears that the inhibition of lipid peroxidation by olive phenols can be satisfactorily interpreted by assuming that they essentially reduce the AAPH-derived initiating radicals. Overall, olive phenols prove to be efficient scavengers of hydrophilic peroxyl radicals with a long lasting antioxidant effect owing to the residual activity of some of their oxidation products.     

Photopolymerization of Acrylonitrile: Benzophenone-Isopropanol System as Initiator

Abstract

Irradiation of benzophenone in the presence of a suitable hydrogen donor like alcohol leads to benzpinacol and the ketone as sole products. This reaction proceeds through ketyl radical intermediates. This photoredox system may be used for photopolymerization. Photopolymerization of acrylonitrile using isopropanol and benzophenone combination as initiator has been studied. The formation of the polymer is directly proportional to irradiation time, [acrylonitrile] and [isopropanol]. The rate of polymerization increases with an increase in concentration of benzophenone to an optimum and a further increase in benzophenone concentration decreases the polymerization rate. A suitable mechanism is suggested.     

Antioxidant activity and chemical composition of essential oil from Atriplex undulata

The essential oil from aerial parts (stems and leaves) of Atriplex undulata (Moq) D. Dietr. (Chenopodiaceae) has been studied for its in vitro antioxidant activity. The chemical composition of the oil obtained by hydrodistillation was determined by GC and GC-MS. The major constituents were p-acetanisole (28.1%), beta-damascenone (9.3%), beta-ionone (5.1%), viridiflorene (4.7%) and 3-oxo-alpha-ionol (2.2%). The antioxidant activity of the oil was determined by two methods: Crocin bleaching inhibition (Krel = 0.72 +/- 0.15) and scavenging of the DPPH radical (IC50 = 36.2 +/- 1.6 microg/mL). The presence of active compounds like p-acetanisole, carvone, vanillin, 4-vinylguaiacol, guaiacol, terpinen-4-ol and alpha-terpineol could explain the antioxidant activity observed for this oil.