Development of a new class of potential antiatherosclerosis agents: NO-donor antioxidants

A new class of NO-donor phenol derivatives is described. The products were obtained by joining appropriate phenols with either nitrooxy or 3-phenylsulfonylfuroxan-4-yloxy moieties. All the compounds proved to inhibit the ferrous salt/ascorbate induced lipidic peroxidation of membrane lipids of rat hepatocytes. They were also capable of dilating rat aorta strips precontracted with phenylephrine.     

Leaf senescence and activities of the antioxidant enzymes

Senescence is a genetically regulated process that involves decomposition of cellular structures and distribution of the products of this degradation to other plant parts. Reactions involving reactive oxygen species are the intrinsic features of these processes and their role in senescence is suggested. The malfunction of protection against destruction induced by reactive oxygen species could be the starting point of senescence. This article reviews biochemical changes during senescence in relation to reactive oxygen species and changes in antioxidant protection.     

New promising antioxidants based on 2,6-dimethylphenol

Three new sulfur-containing derivatives of 2,6-dimethylphenol were synthesized. Their antioxidative activity, mutagenicity, and genotoxicity were examined by bacterial tests and by calculating the dominant lethal mutations in murine embryonic cells. It was shown that all the compounds synthesized have a marked antioxidative effect and have no genotoxic and mutagenic properties. One of the antioxidants, 4-(3-dodecylthiopropyl)-2,6-dimethylphenol, increases the survival of cells of both the wild-type Escherichia coli strain and bacterial strains defective in the genes of repair enzymes and has a more distinct antioxidative effect than the classic antioxidants α-tocopherol and trolox, increasing the survival of cells devoid of repair enzymes.     

Oxidative stress and antioxidant content in Chlorella vulgaris after exposure to ultraviolet-B radiation

Growth of Chlorella vulgaris was measured in cultures irradiated with 0, 0.8, 2.0 and 4.4 kJ m² UV-B. Growth expressed as chlorophyll content, declined significantly with increased UV-B dose. Ultraviolet-B irradiated cultures in log phase of growth showed a 284% increase in oxygen radical generation and a 145% increase in lipid peroxidation compared with unirradiated cultures, whereas cultures in the stationary growth phase showed no significant changes in these parameters. The activities of superoxide dismutase and catalase increased by 40 and 500%, respectively, after exposure to a UV-B dose of 4.4 kJ m⁻². Contents of the lipophilic antioxidants α-tocopherol and β-carotene increased by 180 and 63 amol cell⁻¹ respectively, between log and stationary phases in unirradiated cultures; but in UV-B-irradiated cultures these increases were significantly depressed. Photoreducing capacities of chloroplasts were decreased following UV-B irradiation of both isolated chloroplasts and those isolated from irradiated algae. Cells exposed to UV-B exhibited increased size and starch accumulation. These results suggest that oxidative stress conditions related to UV-B exposure trigger an antioxidant response that includes an increase in the activity of the antioxidant enzymes (superoxide dismutase and catalase).     

Attenuation of cyclophosphamide induced toxicity by squalene in experimental rats

Cyclophosphamide (CP) is a widely used antineoplastic drug, which could cause toxicity of the normal cells due to its toxic metabolites. In this study, the protective role of squalene (SQ) towards the tissue defense system in the toxicity induced by CP (150 mg/kg b.w., twice, in 2 consecutive days) was studied in the experimental rats. The significant (P < 0.05) alterations in the levels of enzymic [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR)] and non-enzymic antioxidants [total reduced glutathione (GSH), Vitamin E (Vit.E), Vitamin C (Vit.C) and ceruloplasmin] of the heart, red blood cell (RBC) hemolysate and plasma were investigated in the CP toxicity. Alterations in the levels of thiobarbutric acid reactive substance (TBARS) in heart, RBC hemolysate and plasma were also observed as a measure of lipid peroxidation (LPO). These pathological alterations due to CP administration were attenuated by the oral treatment of SQ at a dose of 0.4 ml/day/rat. These observations demonstrate the protective role of SQ towards the tissue defense system of the rats in the CP induced toxicity.     

Relationship between lipids and aflatoxin biosynthesis

This paper describes the key role of lipids on fungal growth and of lipoperoxidation on the output of aflatoxin biosynthesis both in vitro and in vivo. In vitro BHA, BHT and cysteamine, depending their concentration, are capable of reducing or blocking aflatoxin output induced by lipoperoxides or halomethanes in cultures ofAspergillus flavus orA. parasiticus without affecting fungal growth. In vivo BHA and BHT significantly reduced aflatoxin production on wheat, maize and sunflower inoculated with aflatoxigenicAspergilli essentially by preventing fungal growth. In vivo the seeds surface lipids represent a very important carbon source for fungal growth.     

绿茶抗氧化剂成分抑制突变作用的初步研究

绿茶水溶性提取物及茶叶中抗氧化剂成份具有明显的抑制AFB_1及Bap诱导的鼠伤寒沙门氏菌回复突变作用。这种抗氧化剂成份还可以抑制AFB_1和Bap诱导的V79细胞基因正向突变,以及AFB_1诱导的V79细胞SCE和染色体畸变。本实验结果提示,绿茶中抗氧化剂成份可能对AFB_1及Bap的致癌性具有抑制作用。本文就茶叶抗氧化剂抑制突变的可能机制进行了初步讨论。     

Indications that paraoxonase-1 contributes to plasma high density lipoprotein levels in familial hypercholesterolemia

HDL-associated paraoxonase type 1 (PON1) can protect LDL and HDL against oxidative modification in vitro and therefore may protect against cardiovascular disease. We investigated the effects of PON1 levels, activity, and genetic variation on high density lipoprotein-cholesterol (HDL-C) levels, circulating oxidized LDL (OxLDL), subclinical inflammation [high-sensitive C-reactive protein (Hs-CRP)], and carotid atherosclerosis. PON1 genotypes (L55M, Q192R, -107C/T, -162A/G, -824G/A, and -907G/C) were determined in 302 patients with familial hypercholesterolemia. PON1 activity was monitored by the hydrolysis rate of paraoxon, diazoxon, and phenyl acetate. PON1 levels, OxLDL, and Hs-CRP were determined using an immunoassay. The genetic variants of PON1 that were associated with high levels and activity of the enzyme were associated with higher HDL-C levels (P values for trend: 0.008, 0.020, 0.042, and 0.037 for L55M, Q192R, -107C/T, and -907G/C, respectively). In addition to the PON1 genotype, there was also a positive correlation between PON1 levels and activity and HDL-C (PON1 levels: r = 0.37, P < 0.001; paraoxonase activity: r = 0.23, P = 0.01; diazoxonase activity: r = 0.29, P < 0.001; arylesterase activity: r = 0.19, P = 0.03). Our observations support the hypothesis that both PON1 levels and activity preserve HDL-C in plasma.     

<Emphasis Type="Italic">In vitro</Emphasis> propagation of <Emphasis Type="Italic">Acacia sinuata</Emphasis> (Lour.) Merr. from nodal segments of a 10-year-old tree

Summary An in vitro propagation protocol has been developed using nodal explants from a mature ‘elite’ tree of Acacia sinuata. Tissue browning was circumvented by soaking surface-disinfected explants in a solution of antioxidant (238 μM citric acid). Maximum shoot proliferation (75.2%) was achieved from nodal explants collected during the December to March season in Murashige and Skoog's (MS) medium supplemented with 8.9μM 6-benzyladenine (BA), 2.5μM thidiazuron (TDZ), and 135.7μM adenine sulfate (AS) at the end of the first transfer following initial culture (60 d after inoculation). Gibberellic acid (GA₃) at 1.8 μM promoted shoot elongation. The number of shoots was increased by (1) repeated subculturing of nodal explants on fresh medium with the same composition, and (2) using microcuttings from in vitro-regenerated shoots on MS medium containing 6.6 μM BA where each node produced four shoots. When transferred to half-strength MS medium augmented with 7.4 μM indolebutyric acid (IBA) in vitro-regenerated shoots produced prominent roots. Rooted plants were hardened and successfully established in soil. This protocol yielded an average of 100 plants per nodal explant over a period of 3 mo.     

Antioxidant actions of plant foods: Use of oxidative DNA damage as a tool for studying antioxidant efficacy

Plant-food-derived antioxidants and active principles such as flavonoids, hydroxycinnamates (ferulic acid, chlorogenic acids, vanillin etc.), β-carotene and other carotenoids, vitamin E, vitamin C, or rosemary, sage, tea and numerous extracts are increasingly proposed as important dietary antioxidant factors. In this endeavor, assays involving oxidative DNA damage for characterizing the potential antioxidant actions are suggested as in vitro screens of antioxidant efficacy. The critical question is the bioavailability of the plant-derived antioxidants.     

Selection of antioxidants against ovarian oxidative stress in mouse model

Oxidative stress (OS) plays an important role in the process of ovarian granulosa cell apoptosis and follicular atresia. The aim of this study was to select antioxidant against OS in ovary tissue. Firstly, we chose the six antioxidants and analyzed the reactive oxygen species (ROS) level in the ovary tissue. The results showed that proanthocyanidins, gallic acid, curcumin, and carotene decrease the ROS level compared with control group. We further demonstrated that both proanthocyanidins and gallic acid increase the antioxidant enzymes activity. Moreover, change in the ROS level was not observed in proanthocyanidins and gallic acid group of brain, liver, spleen, and kidney tissues. Finally, we found that proanthocyanidins and gallic acid inhibit pro‐apoptotic genes expression in granulosa cells. Taken together, proanthocyanidins and gallic acid may be the most acceptable and optimal antioxidants specifically against ovarian OS and also may be involved in the inhibition of granulosa cells apoptosis in mouse ovary.     

过氧亚硝基-鲁米诺化学发光体系的改进

建立了一个测定过氧亚硝基阴离子（ONOO^－）化学发光的改进体系,测试了某些抗氧化剂清除ONOO^－的作用,其体系的组成和启动发光的程序如下：向pH 10.5碳酸缓冲液配的0.01 mol/L浓度NaN₃溶液通O₃ 30 s,取其800 μl原位注入含有100 μl水配样品和100 μl的0.001 mol/L鲁米诺溶液中,启动化学发光（chemiluminescence, CL）,立即测定每6秒的脉冲数（CP6S）,连续测定10～30次.根据实际需要,选其某一次的CL强度作为评判指标,对比抗氧化剂的活性.该发光体系灵敏、简便、且较稳定,最低可检测限为8.74 μmol/L的ONOO^－量,线性范围为8.74～74.04 μmol/L.批内变异系数3.35%（n=10）,批间变异系数5.52%（n=10）.测得维生素C(Vit.C)、茶多酚（EGCG）、原花菁素、硫脲皆有抑制CL,即清除ONOO^－的作用.     

Hydroxy‐plastochromanol and plastoquinone‐C as singlet oxygen products during photo‐oxidative stress in Arabidopsis

In the present study, we have shown that hydroxy‐plastochromanol and plastoquinone‐C, the hydroxy derivatives of plastochromanol and plastoquinone‐9, respectively, are specifically formed from the parent compounds upon action of singlet oxygen and can be regarded as stable, specific, natural products of singlet oxygen action during photo‐oxidative stress in vivo. The presented data indicate that plastoquinone‐C formation dominates mainly during relatively short periods of high light stress where efficient production of singlet oxygen takes place, whereas hydroxy‐plastochromanol is rather formed under conditions of long‐term, less pronounced generation of singlet oxygen. An interesting observation was that hydroxy‐plastochromanol is formed even at very low light conditions (5–10 μmol photons m^?2 s^?1), indicating that singlet oxygen is generated not only during high light stress but also its formation by photosystem II is inseparably connected with the functioning of this photosystem even at the lowest light intensities.     

Control of Aspergillus growth and aflatoxin production using antioxidants at different conditions of water activity and pH

AIMS: The effect of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB) and propyl paraben (PP) (at concentrations of 1, 10 and 20 mmol l(-1)) on germination, growth and aflatoxin B1 production by Aspergillus section Flavi was evaluated. METHODS AND RESULTS: Studies on the percentage of spore germination, elongation rate, growth rate and aflatoxin B1 production were carried out in vitro in relation to water activity (aw) at 0.982, 0.937, 0.809 and 0.747 values. At 0.809 and 0.747aw values none of the isolates was able to germinate. Overall, PP and BHA were the antioxidants most effective at inhibiting germination of both species. In the presence of the lowest concentration of BHA and PP (1 mmol l(-1)) the conidial germination percentage ranged from 2 to 19% after 15 h of incubation at the highest water activity tested. BHA and PP at 10-20 mmol l(-1) completely inhibited conidial germination. The antioxidants more efficient in controlling Aspergillus elongation rate were PP, BHT and BHA. All strains were much more sensitive to all antioxidants tested on the percentage of spore germination and growth rate at 0.937aw. The antioxidants PP and BHA completely inhibited aflatoxin B1 production by all strains when added at 1 mmol l(-1). Decreased aflatoxin B1 levels in comparison with the control, were observed with BHT at 1, 10 and 20 mmol(-1) with the strain T20 at 0.982aw. In contrast, stimulation was observed with the antioxidant THB at 10 and 20 mmol l(-1) at 0.937aw with the strains T20 and T23. The effect of BHA and PP at 1 mmol l(-1) on lag phase and growth rate was maintained in the pH range between 6 and 8. At all pH values the inhibitory effect of BHA was higher than PP. No aflatoxin B1 was detected at all pH values. CONCLUSIONS: The data show that BHA and PP could be considered as effective fungitoxicants for A. flavus and A. parasiticus. SIGNIFICANCE AND IMPACT OF THE STUDY: The information obtained show promise for controlling growth and aflatoxin B1 in stored maize. Futher studies should be carried out to examine the potential for antioxidants, such as BHA and PP to effectively control both growth and aflatoxin production.     

Intracellular trafficking of vitamin E in hepatocytes: the role of tocopherol transfer protein

The term vitamin E denotes a family of tocopherols and tocotrienols, plant lipids that are essential for vertebrate fertility and health. The principal form of vitamin E found in humans, RRR-alpha-tocopherol (TOH), is thought to protect cells by virtue of its ability to quench free radicals, and functions as the main lipid-soluble antioxidant. Regulation of vitamin E homeostasis occurs in the liver, where TOH is selectively retained while other forms of vitamin E are degraded. Through the action of tocopherol transfer protein (TTP), TOH is then secreted from the liver into circulating lipoproteins that deliver the vitamin to target tissues. Presently, very little is known regarding the intracellular transport of vitamin E. We utilized biochemical, pharmacological, and microscopic approaches to study this process in cultured hepatocytes. We observe that tocopherol-HDL complexes are efficiently internalized through scavenger receptor class B type I. Once internalized, tocopherol arrives within approximately 30 min at intracellular vesicular organelles, where it co-localizes with TTP, and with a marker of the lysosomal compartment (LAMP1), before being transported to the plasma membrane in a TTP-dependent manner. We further show that intracellular processing of tocopherol involves a functional interaction between TTP and an ABC-type transporter.     

Peroxynitrite-Induced Apoptosis in Epithelial (T84) and Macrophage (RAW 264.7) Cell Lines: Effect of Legume-Derived Polyphenols (Phytolens)

Peroxynitrite (ONOO⁻) has been proposed as a mediator of gut inflammation and as an inducer of cell death by apoptosis. Phytolens (PHY), a water-soluble extract of polyphenolic antioxidants from nonsoy legumes (Biotics Research Corp, patent pending), was evaluated as a cytoprotective agent in human colonic (T84) and murine macrophage (RAW 264.7) cell lines. In the antioxidant testing, PHY showed a significant free radical scavenging ability against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and superoxide (O₂^•) radicals with an IC₅₀of 4.44 and 5.87 μg/ml against DPPH and O₂^•, respectively. Apoptosis (DNA fragmentation) was measured by an ELISA technique. Cells were exposed to oxidative stress by treating them with peroxynitrite (100–300 μM) for 4 h in the presence and absence of PHY. Peroxynitrite elicited a dose-dependent increase in DNA fragmentation in both cell lines compared to the control group receiving decomposed ONOO⁻. PHY (10, 30, or 50 μg/ml) significantly attenuated the degree of apoptosis in T84 cells induced by ONOO⁻(P< 0.05). PHY (10–100 μg/ml) did not directly affect T84 cell viability or induce apoptosis after 4 h or overnight exposure. RAW 264.7 cells exposed to PHY alone (>30 μg/ml) for 4 h displayed decreased cell viability (P< 0.05) and increased apoptosis (P< 0.05). Phytolens may have beneficial effects on inflammation by attenuating peroxynitrite-induced apoptosis. The sparing of epithelial cells while compromising the viability of macrophages suggests that PHY may be beneficial in autoimmune disorders.     

Oxidative stress and heart failure

Various abnormalities have been implicated in the transition of hypertrophy to heart failure but the exact mechanism is still unknown. Thus heart failure subsequent to hypertrophy remains a major clinical problem. Recently, oxidative stress has been suggested to play a critical role in the pathogenesis of heart failure. Here we describe antioxidant changes as well as their significance during hypertrophy and heart failure stages. Heart hypertrophy in rats and guinea pigs, in response to pressure over-load, is associated with an increase in antioxidant reserve and a decrease in oxidative stress. Hypertrophied rat hearts show increased tolerance for different oxidative stress conditions such as those imposed by free radicals, hypoxia-reoxygenation and ischemia-reperfusion. On the other hand, heart failure under acute as well as chronic conditions is associated with reduced antioxidant reserve and increased oxidative stress. The latter may have a causal role as suggested by the protection seen with antioxidant treatment in acute as well as in chronic heart failure. It is becoming increasingly apparent that, anytime the available antioxidant reserve in the cell becomes inadequate, myocardial dysfunction is imminent.     

Ceratophyllum demersum L. and Potamogeton alpinus Balb. from Iset’ River,Ural Region,Russia Differ in Adaptive Strategies to Heavy Metals Exposure – A Comparative Study

We examined the uptake of five heavy metals (Cu, Fe, Ni, Zn, and Mn) in Ceratophyllum demersum L. (hornwort) and Potamogeton alpinus Balb. (pondweed) from Iset’ river, Ural region, Russia. This study was conducted in a territory that is highly urbanized where the surface waters are contaminated by a wide spectrum of pollutants. The environmental situation in this territory drastically deteriorated due to anthropogenic activity. The water quality in most of the water bodies in the Ural region is rather poor. In a comparative study ofC. demersum and P. alpinus, differential accumulation pattern was noted for heavy metals (HMs). Higher amounts of HMs accumulated in C. demersum compared to P. alpinus. Also it was shown that in leaves of C. demersum there were high amount of total phosphorus, nitrogen, organics acids and ash; high activity of guaiacol peroxidase; high content of non-enzymatic antioxidants viz., flavonoids, ascorbate, glutathione and proline; high amount of thiols (soluble and membrane bound) compared to P. alpinus.     

Cellular lifespan and senescence: a complex balance between multiple cellular pathways

The study of cellular senescence and proliferative lifespan is becoming increasingly important because of the promises of autologous cell therapy, the need for model systems for tissue disease and the implication of senescent cell phenotypes in organismal disease states such as sarcopenia, diabetes and various cancers, among others. Here, we explain the concepts of proliferative cellular lifespan and cellular senescence, and we present factors that have been shown to mediate cellular lifespan positively or negatively. We review much recent literature and present potential molecular mechanisms by which lifespan mediation occurs, drawing from the fields of telomere biology, metabolism, NAD⁺ and sirtuin biology, growth factor signaling and oxygen and antioxidants. We conclude that cellular lifespan and senescence are complex concepts that are governed by multiple independent and interdependent pathways, and that greater understanding of these pathways, their interactions and their convergence upon specific cellular phenotypes may lead to viable therapies for tissue regeneration and treatment of age‐related pathologies, which are caused by or exacerbated by senescent cells in vivo.