Deoxyribose Degradation Research Articles

Comparison of effects of some cyclic chalcone analogues on selected mitochondrial functions.

In earlier studies, cytotoxity of chalcones (1) and cyclic chalcone analogues E-2-arylidene-tetralones (2) and -benzosuberones (3) towards various murine and human tumour cells has been tested. Preliminary biochemical investigations showed the compounds to inhibit protein and DNA syntheses. It was also found that the compounds affect the cellular thiol status of the treated cells. In order to gain new insights into the cytotoxic mechanism of the compounds effects of some previously investigated 2 and 3 derivatives on isolated rat liver mitochondria was investigated. It was found that the most cytotoxic compounds 2c and 3b significantly decreased the GSH level of the mitochondria. Incubation of the investigated chalcones with reduced GSH under cell-free conditions indicated spontaneous conjugation (non-redox) reaction at pH 7.4 and pH 9.0. Investigation of antioxidant capacity of the compounds by monitoring time course of the Fenton-reaction initiated in vitro degradation of 2-deoxyribose showed the compounds to display hydroxyl radical scavenger activity. Investigation of respiratory control ratio of 2c and 3b showed the compounds to display an inhibitory effect on respiration, compound 2b, however, displayed rather an uncoupling effect. The experiments provide further details of cytotoxic effects of the synthetic chalcones displaying dual - cytotoxic and cytoprotective - effects.

Antioxidant activity of herb extracts from five medicinal plants from Lamiaceae, subfamily Lamioideae

Five medicinal plants from the subfamily Lamioideae of the Lamiaceae were tested for antioxidant activity and screened for polyphenols content. Aerial parts of Ballota nigra, Lamium maculatum, Leonurus cardiaca, Marrubium vulgare, and Galeopsis tetrahit were extracted with methanol (MeOH) and subsequently partitioned by liquid-liquid extraction between petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EA) and n-butanol (BuOH). All 25 extracts and subfractions were assayed for •DPPH and HO• scavenging and phosphomolybdenum reduction. Total polyphenols and free hydroxycinnamic acids were determined by spectrophotometric assays. Predictably, all species possess remarkable antioxidant capacity, but the relative differences between species and fractions depended on the method of testing. The LLE method allows the partitioning of most active polyphenols into the polar solvents. The BuOH fraction of L. cardiaca had a lowest EC50for •DPPH scavenging - 4.45 µg/ml. The maximum inhibition of deoxyribose degradation of was demonstrated for B. nigra EA and BuOH fractions (79.32 ± 1.62% and 82.04 ± 2.28%, respectively). B. nigra EA, and L. cardiacaBuOH fractions had also the highest reducing capacity of 318.6 ± 14.7 mg/g and 271.4 ± 2.4 mg/g ascorbic acid equivalents. The studied plants can provide efficient antioxidant protection by complementary mechanisms, such as free radical scavenging and metal ions reduction. However, only polar fractions from L. cardiaca and B. nigra are the most potent. Key words: Lamioideae, antioxidant, polyphenols, deoxyribose, Ballota nigra,Galeopsis tetrahit, Lamium maculatum, Leonururs cardiaca, Marrubium vulgare.

Butane-2,3-dionethiosemicarbazone: An oxime with antioxidant properties

Oximes are compounds generally used to reverse the acetylcholinesterase (AChE) inhibition caused by organophosphates (OPs). The aim of this study was to examine the capacity of the butane-2,3-dionethiosemicarbazone oxime to scavenge different forms of reactive species (RS) in vitro, as well as counteract their formation. The potential antioxidant and toxic activity of the oxime was assayed both in vitro and ex vivo. The obtained results indicate a significant hydrogen peroxide (H 2O 2), nitric oxide (NO) and 1,1-diphenyl-2-picrylhydrazyl (DPPH ) radical scavenging activity at 0.275, 0.5 and 5 μM of oxime, respectively ( p ≤ 0.05). The oxime exhibited a powerful inhibitory effect on dihydroxybenzoate formation (25 μM) ( p ≤ 0.05) and also decreased deoxyribose degradation induced by Fe 2+ and via Fenton reaction (0.44 and 0.66 mM, respectively) ( p ≤ 0.05). The oxime showed a significant inhibitory effect on σ-phenantroline reaction with Fe 2+ (0.4 mM) suggesting a possible interaction between the oxime and iron. A significant decrease in the basal and pro-oxidant-induced lipid peroxidation in brain, liver, and kidney of mice was observed both in vitro and ex vivo ( p ≤ 0.05). In addition, in our ex vivo experiments the oxime did not depict any significant changes in thiol levels of liver, kidney and brain as well as did not modify the δ-aminolevulinate dehydratase (δ-ALA-D) activity in these tissues. Taken together our results indicate an in vitro and ex vivo antioxidant activity of the oxime possibly due to its scavenging activity toward different RS and a significant iron interaction.

Anti-free radical activities of kaempferol isolated from Acacia nilotica (L.) Willd. Ex. Del.

In the present study the polyphenolic compound has been isolated from methanol extract of Acacia nilotica Willd. Ex. Del. which has been identified as kaempferol (AN-5) by NMR and mass spectroscopy. The antioxidant potential of the AN-5 was demonstrated in several in vitro assays: measuring the proton radical scavenging activity (DPPH scavenging assay), hydroxyl radical scavenging activity (deoxyribose degradation assay), metal chelating activity, reducing power and inhibition of lipid peroxidation. It was found that the effect of the compound AN-5 was strongly dose dependent up to the concentrations 1-50 microg/ml in DPPH assay and 1-100 microg/ml in deoxyribose degradation assay but did not show further change above the highest concentrations.

Essential Oil Composition, Antibacterial and Antioxidant Activities of <i>Mentha aquatica</i> Growing in Ethiopia

The in vitro antibacterial and antioxidant activities of the essential oil of Mentha aquatica L. (Lamiaceae) growing in Ethiopia were studied. The chemical composition of the oil was also investigated by using capillary gas chromatography-mass spectrometry. A total of 34 compounds representing 99.4% of the oil have been identified. Menthofuran (70.5%) was characterized as the main component with limonene and pmenthone constituting 9.42 and 7.20% of the oil, respectively. In general, the oil showed a remarkable activity against the Gram-positive bacteria tested of which Staphylococcus aureus 29737, S. aureus ML267, Sarcina luteus 9341 and Bacilus pumilus 8241 strains were the most susceptible. The minimum inhibitory concentration (MIC) values of the oil against these organisms were found to be less than 5 μg/ml. The antioxidant activity of the oil was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays and was found to possess good radical scavenging activity with IC50 values of 11.2 and 3.74 μl/ml, respectively. Keywords: antibacterial, antioxidant, Mentha aquatica, essential oil, capillary gas chromatography-mass spectrometryEthiopian Pharmaceutical Journal Vol. 26 (1) 2008: pp. 9-16

A study on antioxidant, free radical scavenging, anti-inflammatory and hepatoprotective actions of Aegiceras corniculatum (stem) extracts

Aim of the study The present study was conducted to evaluate the antioxidant, anti-inflammatory and hepatoprotective potential of Aegiceras corniculatum Linn. Blanco (Aegicerataceae). Methods and results The n-hexane, ethyl acetate and methanol extracts, derived from Aegiceras corniculatum stems, scavenged superoxide anions (O 2 −) and hydroxyl radicals ( OH) in nitro blue tetrazolium reduction and deoxyribose degradation assays, respectively. All the extracts inhibited the process of lipid peroxidation at its initiation step. Additionally, in rat liver microsomes n-hexane and ethyl acetate extracts also caused termination of radical chain reaction supporting their scavenging action towards lipid peroxy radicals (LOO ). Moreover, increased production of O 2 − in human neutrophils, stimulated by phorbol-12-myristate-13-acetate (PMA) and/or opsonized zymosan were also suppressed (IC 50 ∼3–20 μg/mL). Thereby, revealing the ability of plant extracts to antagonize the oxidative stress via interference with NADPH oxidase metabolic pathway. These in vitro results coincide with the reduction in the glucose oxidase-induced paw edema in mice in the presence of ethyl acetate and methanol extracts (10, 50, and 100 mg/kg, i.p.). Plant extracts (250, 500 and 1000 mg/kg, p.o.) also significantly protected the carbon tetrachloride (CCl4)-induced oxidative tissue injury in rat liver. This was reflected by a ∼60% decline in the levels of serum aminotransferase enzymes. Conclusion Aegiceras corniculatum extracts found to possess pronounced antioxidant effect that may be at least in part related to its anti-inflammatory and hepatoprotective activities. This study provides a scientific basis for the ethnomedical claims that Aegiceras corniculatum is effective against inflammation and liver injury.

Antioxidant activity of an aminothiazole compound: Possible mechanisms

Oceans are among the richest natural sources of many bioactive compounds. Several of these compounds have shown pharmacological activities for many diseases. Dendrodoine (5-[(3- N-dimethylamino)-1,2,4-thiadiazolyl]-3-indanyl methanone) is an alkaloid extracted from the marine tunicate Dendrodoa grossularia. Aminothiazoles have a wide range of biological activities including anti-tumor and antioxidant properties. The aim of our study was to examine the antioxidant ability of an aminothiazole derivative, dendrodoine analogue (DA) [(4-amino-5-benzoyl-2-(4-methoxy phenylamino) thiazole] which has been chemically synthesized and is similar to dendrodoine. In all the biochemical assays used in our study, corresponding to different levels of protection, DA showed concentration dependent antioxidant ability. DA (3.07 μM) showed an ability to inhibit 2,2′-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical formation to the extent of 0.17 μM of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). The ferric complex reducing ability of 3.07 μM DA was equivalent to 110 μM Trolox. 3.07 μM DA gave 84% protection against deoxyribose degradation, a measure of hydroxyl radical scavenging. DA also has an ability to scavenge NO radical, 3.07 μM DA effecting 20% scavenging. Concentration dependent inhibition of lipid peroxidation and protein oxidation induced by 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) and ascorbate-Fe 2+ was observed with low concentrations of DA (1.5–3.07 μM). Mechanistic studies using pulse radiolysis revealed that DA scavenges peroxyl radicals with a bimolecular rate constant of 3 × 10 8 M −1 s −1. Moreover, the initially formed nitrogen-centered radical gets transformed into sulfur-centered radical before furnishing any final product. Our results indicated that DA can be a free radical scavenger and potential antioxidant for future application.

Antioxidant activity of the phenol rich fractions of leaves of Chukrasia tabularis A. Juss.

The present study was designed to explore the antioxidant potential of chloroform, ethyl acetate, n-butanol and water fractions of 80% methanol extract of leaves Chukrasia tabularis by 2,2′-diphenyl-1-picrylhydrazyl (DPPH), deoxyribose degradation (non-site specific and site specific), reducing power and DNA nicking assays. The different fractions showed significant activities in all the free radical scavenging tests and these findings have also shown direct relationship between antioxidant activity and phenolic content. Among the fractions, ethyl acetate fraction exhibited highest inhibition of 93.14%, 89.99%, 87.04% in DPPH, non-site specific and site specific deoxyribose degradation assays, respectively and 91.20% reduction of ferricyanide to give Prussian blue coloured complex in reducing power assay at maximum concentration tested. This preliminary study indicates the antioxidant activity of the leaves of Chukrasia tabularis, and moreover the results showed correlation with the amount of phenolic content present in different fractions.

Antioxidant Activities of Three Rubus Species Growing in Ethiopia

In Ethiopian traditional medical practices some species of the genus Rubus (Rosaceae) are used for the treatment of diabetes mellitus, one of the disease conditions in which free radicals and oxidative stress have been implicated. In the present study extracts prepared from three members of the genus, namely Rubus apetalus Poir, R. niveus Thunb and R. steudneri Schweinf were investigated for their in vitro radical scavenging activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays. The 80% methanol extract, and acetone and methanol soxhlet fractions of the three plants tested showed antioxidant activity in a concentration-dependent manner. The 80% methanolic extract of R. steudneri showed the strongest activity in the DPPH radical scavenging assay (IC50 = 6.5 mg/ml). In the deoxyribose degradation assay the 80% methanol, acetone and methanol extracts of R. niveus displayed potent activity with IC50 values of 0.64, 0.6 and 0.61 μg/ml, respectively. Ascorbic acid (vitamin C) was used as a positive control in the DPPH assay (IC50 = 4.5 μg/ml) and butylhydroxytoluene, in the deoxyribose degradation assay (IC50 = 4.76 μg/ml). The results of the present study suggest that the antioxidant activity of the studied plants may contribute to their purported uses as antidiabetic agents. The work further indicated that the antioxidant active principles of the plants reside in the polar fraction of the extracts. Keywords: Rubus spp., Rosaceae, radical scavenging activity, DPPH assay, deoxyribose degradation assayEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 103-110

<i>In Vitro</i> Radical Scavenging Activity of the Leaf and Bark Extracts of <i>Senna singueana</i> (Del). Lock

The leaves and bark of Senna singueana (Del). Lock (family: Fabaceae) are traditionally used in some parts of Ethiopia, for the treatment of a form of skin cancer locally called ‘Minshiro Nekersa\'. Total extracts and solvent fractions obtained from the leaves and bark; and fractions obtained from solid-phase extraction and TLC of the leaf extract were prepared and tested for their radical scavenging activity using DPPH (1,1- diphenyl-2-picrylhydrazyl) and deoxyribose degradation inhibition assays. The results revealed that all the samples tested possess strong DPPH radical scavenging activity and moderate deoxyribose degradation inhibitory effect. The IC50 values of the total extracts and solvent fractions ranged from 6.16 to 200.10 μg/ml in DPPH assay and 262.77 μg/ml to 1457.63 μg/ml in deoxyribose degradation inhibition assay. The TLC separated bands showed IC50 values ranging from 8.89 to 53.83 μg/ml, and 72.17 to 849.18 μg/ml, respectively, in the two assays. The positive control standard compounds ascorbic acid (for the DPPH assay) and butylhydroxytoluene (for the deoxyribose degradation inhibition assay) showed IC50 values of 4.46 and 4.76 μg/ml, respectively. As free radicals are known to be involved in carcinogenesis, radical scavengers can short-cut free radical mediated critical steps that lead into carcinogenesis. It was thus proposed that the observed radical scavenging activity of S. singueana may contribute partly to the possible scientific basis for the traditional anticancer use of the plant. Keywords: Senna singueana, Fabaceae, radical scavenging activity, DPPH assay, deoxyribose degradation inhibition assayEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 77-84

Essential Oil Composition, Antibacterial and Antioxidant Activities of Four <i>Mentha</i> Species Growing in Ethiopia

The essential oils obtained by hydrodistillation from the leaves of Mentha arvensis L., M. longifolia L., M. piperita L., and M. spicata L., were analyzed by gas chromatography (GC-FID) and gas chromatography/ mass spectrometry (GC/MS). In addition, the antibacterial activities of the oils were evaluated against 20 bacterial strains and their radical scavenging potentials were determined in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays. Oxygenated monoterpenes were found to be major constituents of all the oils. The essential oil of M. spicata exhibited a significant wide spectrum antibacterial activity against all test strains including multiresistant strains of Pseudomonas aeruginosa and Escherichia coli. The essential oil of M. piperita displayed powerful in vitro radical scavenging activities in both DPPH and deoxyribose degradation assays, with IC50 values of 5.96 μl/ml and 0.57 μl/ml, respectively. The other essential oils also produced concentraion dependant radical scavenging activities with IC50 values ranging between 5.96 and 37.01 μl/ml, and 0.57 and 3.88 μl/ml, in DPPH and deoxyribose degradation assays, respectively. The present study revealed that all the essential oils have the potential to be used as naturally occurring antibacterial and antioxidant agents. Keywords: essential oils, Mentha spp, capillary gas chromatography-mass spectrometry, radical scavenging activity, antibacterial activityEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 91-102

Antioxidant Activities of Ethanol Extracts of Hypericum triquetrifolium. and Hypericum scabroides.

The antioxidative potential of ethanol extracts of Hypericum triquetrifolium. Turra (Hypericaceae) and Hypericum scabroides. Robson & Poulter (Hypericaceae) were investigated for the first time using 1,1-diphenyl-2-picrylhydrazyl (DPPH), metal chelating, reducing power, hydroxyl radical, total antioxidant activity, and lipid peroxidation inhibition assays. Both extracts tested were found to be highly active in the DPPH radical scavenging assay. The IC50 values of H. triquetrifolium. (HT) and H. scabroides. (HS) in the DPPH radical scavenging assay were 39.0 and 33.8 μ g/mL, respectively. The amounts of total phenolic compounds were also determined, and total phenolic content of 1 mg H. triquetrifolium. and H. scabroides. ethanol extracts were equivalent to 267 and 333 μ g gallic acid. Metal chelating ability was found to be low compared with EDTA. Both ethanol extracts of Hypericum. species exhibited a high reducing power, suggesting that extracts had strong electron-donating capacity. The degradation of deoxyribose by hydroxyl radicals was shown to be inhibited by Hypericum. extracts, acting mainly by scavenging hydroxyl radicals rather than as chelators of iron ions. Total antioxidant activity of ethanol extracts of HT and HS were tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of both extracts were found to be comparable with vitamin E. Moreover, both extracts showed notable capacity to suppress Fe2 +-induced lipid peroxidation in rat brain homogenate. The results obtained in the current study indicate that ethanol extracts of HS and HT are a potential source of natural antioxidants.

Toluene and P-Xylene Mixture Exerts Antagonistic Effect on Lipid Peroxidation in vitro

Previous research on a group of workers occupationally exposed to styrene, ethylene glycol, toluene, p-xylene and their mixture showed elevated levels of the main products of lipid peroxidation: malondialdehyde and 4-hydroxynonenal (MDA+,4-HNE) in plasma [1]. Moreover, an earlier in vitro study indicated a synergistic interaction between styrene and ethylene glycol on lipid peroxidation [2]. Therefore, it seemed interesting to investigate the effect of combined exposure to toluene and p-xylene on lipid peroxidation and define the type of the interaction. An in vitro model of human placenta mitochondria was used in the study. The concentration of TBARS (thiobarbituric active reagent species) was measured by spectrophotometry, and of hydroxyl radical (.OH) by assessment of deoxyribose degradation. It was investigated whether the administration of coenzyme Q10 (CoQ10) could have a protective function (if given before solvent exposure) or a reparatory function (if given after exposure) in solvent-induced oxidative stress. Exposure to p-xylene at concentrations ranging from 5.3 to 265 microg/ml produced an increase in TBARS concentration. The results showed that p-xylene had a stronger influence on lipid peroxidation than toluene. The mixture of toluene and p-xylene induced an antagonistic effect on lipid peroxidation, measured as TBARS concentration. The mechanism connected with .OH generation was found to play an important role in the oxidative damage to lipids resulting from p-xylene exposure. Administration of coenzyme Q10 at the doses of 3.0 and 12.0 microg/ml successfully decreased the TBARS level that was elevated after solvent exposure. In contrast to the synergistic effect that the mixture of styrene and ethylene glycol had on lipid peroxidation (previous study), an antagonism between toluene and p-xylene could be observed. The coenzyme Q10 can be considered a protective agent against lipid peroxidation.

In VitroAntioxidant and Free Radical Scavenging Activity ofCyperus rotundus

Cyperus rotundus (Family Cyperaceae) is used both as a functional food and as a drug. In this study, the antioxidative potential of a hydroalcoholic extract of C. rotundus (CRE) was evaluated by various antioxidant assays, including antioxidant capacity by the phosphomolybdenum method, total antioxidant activity in linoleic acid emulsion systems, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, hydroxyl radicals, and nitric oxide (NO) scavenging. We further evaluated the reducing potential of the extract as well as Fe(2+)/ascorbate-induced lipid peroxidation in rat liver homogenate. These various antioxidant activities were compared to standard antioxidants such as butylated hydroxytoluene, tocopherol, L-ascorbic acid, and catechin. Total phenolic and flavonoid content of CRE was also determined by a colorimetric method. The extract exhibited high reduction capability and powerful free radical scavenging, especially against DPPH and superoxide anions as well as a moderate effect on NO. CRE also showed inhibited lipid peroxidation in rat liver homogenate induced by Fe(2+)/ascorbate and prevented deoxyribose degradation in both non-site-specific and site-specific assays showing the hydroxyl radical scavenging and metal chelating activity of the hydroalcoholic extract. Moreover, the peroxidation inhibiting activity of CRE was demonstrated in the linoleic acid emulsion system. These results clearly established the antioxidative potency of C. rotundus, which may account for some of the medical claims attributed to this plant.

The Role of Iron Chelation Activity of Wheat Grass Juice in Blood Transfusion Requirement of Intermediate Thalassaemia.

Background: Previously it was thought that the chlorophyll of wheat grass (Triticum astevum) may be the substitute of haemoglobin of RBC having resemblance of similar structure. A group of Austrelian scientists tried to prove that wheat grass juice increases the foetal haemoglobin level 3–5 folds in intermediate thalassaemia patients. A pilot study with wheat grass juice in major thalassaemia patients were done by Dr. Marwa et al in IPGMR, Chandigarh, India. But there is no satisfactory explanation behind the reduced blood transfusion requirements after consumption of wheat grass juice for a long period. The aim of our study was to see the effect of wheat grass juice in blood transfusion requirement in intermediate thalassaemia patients and also do the biochemical analysis of the wheat grass juice.Material & Methods: During period from January 2003 to December 2006 we selected 200 intermediate thalassaemia patients (E-thalassaemia, E-Beta & Sickle thal) in the paediatric oncology department of Netaji Subhash Chandra Bose Cancer Research Institute. The age range of the patients was 1 year to 35 years (median age 18 years). The different types of thalasssaemia were E-Beta Thalassaemia 80% (160 patients), E-Thalassaemia 15% (30 patients) and Sickle Thalassaemia 5% (10 patients). When the wheat grasses were 5–7 days old, the fresh leaves including steams were made fresh juice and had given 30ml of juice daily to all our 200 patients for continuous 6 months. Wheat grass juice was analysed by column chromatography and found to be rich in oxalic acid and malic acid which might have some role in dietary absorption of iron from intestine. Beside that the wheat grass juice was found to contain a unique iron chelating property which was performed by deoxyribose degradation assay. We compared aqueous soluble extract of 5–7th day plant and our dose dependant study showed a significant iron chelating activity of crude extract in comparison to known standard iron chelator desferroxamine (DFO). The active compounds of crude extract of wheat grass may chelate catalytic iron in iron overload disorders when taking systematic dose.Result: The mean levels of haemoglobin before starting wheat grass juice were 6.2gm%. After 6months of wheat grass therapy the mean value for haemoglobin was 7.8gm% (pvalue <. 005). Twenty four patients (12%) require blood transfusion (haemoglobin < 6gm%). The performance status was improved from 60% to 80% (Karnofsky) after wheat grass treatment. The ferritin level of all patients before the study was found to be decreased significantly after wheat grass juice consumption. The mean interval between transfusion were found increased. Being a natural potent iron chelator and H2O2 quencher, it prevents the hydroxyl radical production by Fenton reaction in the RBC. Thus it may prevent the breakdown of plasma membrane of RBC and haemoglobin level becomes stable for a prolonged period.Conclusion: We may conclude that wheat grass juice is an effective alternative of blood transfusion. It's use in intermediate thalassaemia patients should be encouraged.

Antioxidant and Anti-hyperglycemic Activity of Polysaccharide Isolated from Dendrobium chrysotoxum Lindl

Although polysaccharide is believed to play an important role in the medicinal effect of Dendrobium chrysotoxum Lindl (DCL), its role as an antioxidant and in anti-hyperglycemic induction was not reported. In this study, polysaccharide with molecular weight of approximately 150 kDa, herein named DCLP, was isolated from the stem of DCL, and its antioxidative, hypoglycemic and immune stimulating effects were evaluated using various in vitro and in vivo assay systems. DCLP inhibited hydroxyl radicals (*OH)-mediated deoxyribose degradation by scavenging hydroxyl radicals directly as well as by chelating iron ions. DCLP also showed dose-dependent scavenging activity on superoxide anions (O2*) and offered significant protection (p < 0.001) against glucose oxidasemediated cytotoxicity in Jurkat cells. DCLP had immune stimulating effects, as evidenced by the DCLP-mediated increases in the level of DNA synthesis, viability, and cytokine secretion in mouse lymphocytes. Moreover, oral administration of DCLP produced a significant reduction in blood glucose level in alloxan-induced diabetic mice. These findings suggest that DCLP has a potential utility in treating patients who require enhanced antioxidation, immune function and/or hypoglycemic activity.

Application of crocin bleaching and deoxyribose degradation tests to assess antioxidant capacity of capsaicinoids and some selected flavonoids

Application of crocin bleaching and deoxyribose degradation tests to assess antioxidant capacity of capsaicinoids and some selected flavonoids

In vitro scavenging activity for reactive oxygen species by N‐substituted indole‐2‐carboxylic acid esters

The hydroxyl radical (HO*)- and superoxide anion radical (O* (2))-scavenging activity, as well as the singlet oxygen ((1)O(2))-quenching property of N-substituted indole-2-carboxylic acid esters (INDs) were investigated by deoxyribose degradation assay, a chemiluminescence method and the electron spin resonance (ESR) spin-trapping technique. This novel group of compounds was developed as a search for cyclooxygenase-2 (COX-2)-selective enzyme inhibitors. The results obtained demonstrated that of the 16 compounds examined, five inhibited light emission from the superoxide anion radical (O* (2))-DMSO system by at least 60% at a concentration of 1 mmol/L, nine prevented the degradation of deoxyribose induced by the Fenton reaction system (range 3-78%) or scavenged hydroxyl radicals (HO*) directly (range 8-93%) and 14 showed the (1)O(2)-quenching effect (range 10-74%). These results indicate that majority of the indole esters tested possess the ability to scavenge O(-) (2) and HO radicals and to quench (1)O(2) directly, and consequently may be considered effective antioxidative agents.

Synthesis and Study ofl-Dopa−Glutathione Codrugs as New Anti-Parkinson Agents with Free Radical Scavenging Properties

A series of novel molecular combinations (1-4), in which L-dopa (LD) is linked covalently via an amide bond with glutathione (GSH), were synthesized and evaluated as potential anti-Parkinson agents with antioxidant properties. These conjugates were characterized by evaluating solubility, chemical and enzymatic stabilities, and apparent partition coefficient (log P). Derivatives 2 and 4 were tested for their radical scavenging activities, by use of a test involving the Fe(II)/H2O2-induced degradation of deoxyribose. In this study, the antioxidant efficacy of codrugs 1 and 3 was also assessed through the evaluation of plasmatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Furthermore, the central nervous effects and rat striatal concentration of LD and dopamine (DA) have been evaluated after oral administration of codrugs 1 and 3. Tested compounds prolonged the plasma LD levels and were able to induce sustained delivery of DA in rat striatum with respect to an equimolar dose of LD. The results suggest that compounds 1 and 3 could represent useful new anti-Parkinson agents devoid of the pro-oxidant effects associated with LD therapy and potentially able to restore the GSH depletion evidenced in the substantia nigra pars compacta (SNpc) of PD patients.

Evaluation of the Antioxidant Properties of Litchi Fruit Phenolics in Relation to Pericarp Browning Prevention

Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH*) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit.