迷迭香提取物对自由基诱导蛋白质、油脂及DNA氧化的抑制作用

分别采用Cu2+/H2O2、2,2'-偶氮二异丁基脒二盐酸盐[2,2'-azobis(2-amidinopropane)hydrochloride,AAPH]诱导牛血清白蛋白(bovine serum albumin,BSA)氧化和羰基化;Fe2+、偶氮二异庚腈[2,2'-azobis(2,4-di-methyl-valeronitrile),AMVN]诱导亚油酸(linoleic acid,LA)氧化及AAPH诱导鲱鱼精DNA(herring sperm DNA,hsDNA)氧化损伤,研究迷迭香提取物对蛋白质、油脂以及DNA在自由基攻击下发生氧化损伤的抑制作用。结果表明:25μg/mL^500μg/mL的迷迭香提取物能显著抑制自由基诱导的BSA羰基化和LA氧化产物丙二醛(malondialdehyde,MDA)的生成(p<0.05);100μg/mL^500μg/mL的迷迭香提取物能有效降低AMVN诱导的LA共轭二烯产物的生成;25μg/mL^500μg/mL的迷迭香提取物能显著抑制AAPH诱导的hsDNA氧化产物的生成。结论:迷迭香提取物能够有效抑制自由基诱导的蛋白质、油脂及DNA的氧化,其抑制作用随添加浓度的升高而增强。     

枇杷叶科罗索酸抑制人低密度脂蛋白氧化修饰及保护血管内皮细胞氧化损伤作用

从枇杷叶中提取分离制备科罗索酸,采用体外Cu~(2+)诱导低密度脂蛋白(low density lipoprotein,LDL)氧化损伤的体外化学反应模型及2,2’-偶氮二(2-甲基丙基咪)二盐酸盐(2,2’-azobis-2-methyl-propanimidamide dihydrochloride,AAPH)诱导人主动脉内皮细胞(human aortic endothelial cells,HAECs)氧化损伤的细胞模型,考察枇杷叶科罗索酸对LDL氧化过程的抑制作用及对动脉血管内皮细胞氧化损伤的保护作用。体外实验结果表明,枇杷叶科罗索酸在体外10~100μmol/L剂量范围内能有效延长LDL氧化过程中的迟滞期,降低反应动力学曲线的曲线下面积以及降低脂质过氧化物的生成,表明科罗索酸在体外能有效抑制Cu~(2+)诱导的LDL氧化。细胞实验结果表明,在2~10μmol/L剂量范围内能有效降低AAPH所致HAECs的乳酸盐脱氢酶漏出量,维护细胞结构的完整性;提高受损细胞的超氧化物歧化酶、谷胱甘肽过氧化物酶活性,从而提升内皮细胞抵抗氧化应激的能力;降低细胞处于sub-G1/G0状态的比例,减少AAPH所致细胞的坏死或凋亡。表明枇杷叶科罗索酸能在细胞水平有效保护HAECs免受AAPH氧化应激损伤。     

Scavenging effects of lotus seed extracts on reactive nitrogen species

The inhibitory effect of lotus (Nelumbo nicifera) seed extracts extracted with water (LSWE), ethyl acetate (LSEAE) and hexane (LSHE) on reactive nitrogen species, induced by DNA damage in macrophage RAW 264.7 cells, was investigated. The results showed that all extracts could inhibit nitric oxide accumulation in LPS-activated RAW 264.7 cells. The extracts in the range of 0.01–0.2 mg/ml showed a dose-dependent inhibitory effect on the accumulation of nitric oxide upon decomposition of sodium nitroprusside (SNP). The potency of inhibitory activity was in the order: LSEAE > LSWE > LSHE. The results of the comet assay indicated that the three extracts could inhibit DNA damage in macrophage RAW 264.7 cells induced by SNP. In addition, the three samples, at 0.2 mg/ml, showed 63%, 59%, and 38% inhibition of DNA damage in macrophage RAW 264.7 cells induced by peroxynitrite, respectively. All extracts tested were found to be potent peroxynitrite scavengers, capable of preventing the nitration of tyrosine. The data obtained suggest that lotus seed extracts might act as chemopreventers through reduction of excess amounts of nitric oxide.     

菊苣酸对蛋白质氧化损伤的作用

目的：评价菊苣酸对自由基诱导蛋白质氧化损伤的影响。方法：采用Cu2＋/H2O2和2,2’-偶氮二（2-甲基丙 基咪）二盐酸盐（2,2’-azobis(2-methylpropionamidine)dihydrochloride,AAPH）两种不同的自由基诱导体系,分别 诱导牛血清白蛋白（bovine serum albumin,BSA）、小鼠肝脏蛋白和脑蛋白氧化损伤,研究菊苣酸对蛋白氧化损 伤的影响;通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和蛋白免疫印迹法检测蛋白氧化损伤程度。结果：菊苣酸在 100～1 000 μmol/L浓度范围内能够抑制Cu2＋/H2O2诱导的BSA氧化损伤;低浓度菊苣酸对Cu2＋/H2O2诱导的小鼠肝脏 蛋白和脑蛋白氧化损伤具有保护作用,但在高浓度时表现出促氧化作用;在AAPH诱导体系中,菊苣酸对3 种蛋白 模型均具有保护作用,且菊苣酸浓度越高保护效果越好。结论：在Cu2+/H2O2和AAPH两种诱导体系中,菊苣酸对蛋 白质氧化损伤表现出不同的作用效果。     

THE BENEFICIAL EFFECT OF THREE FLAVONOLS AGAINST OXIDATIVE DAMAGE

The ability of three related naturally occurring flavonols in inhibiting Hb oxidation and lipid peroxidation of human erythrocyte membranes was evaluated. The flavonols tested exhibited the following order of potency to inhibit tert‐butyl hydroperoxide‐induced Hb oxidation: quercetin > rutin > morin. The Hb oxidation was estimated by the extent of metHb and hemichrome formation induced by tert‐butyl hydroperoxide. Quercetin or rutin (0.5 mM) increased oxyHb levels about 33% and 10%, respectively. Morin (0.5 mM) was pro‐oxidant, decreasing the oxyHb about 7%. Despite the pro‐oxidant action on Hb oxidation, morin offered greater protection against lipid peroxidation than rutin, preventing the formation of TBA reactive substances by 33.1%, at 0.2 mM. However, quercetin (0.2 mM) provided approximately 50% protection against TBARS formation. The results show that the flavonoids tested are protective for Hb oxidation and lipid peroxidation on erythrocyte membrane subjected to oxidative stress. Quercetin in particular, may be useful in diminishing oxidative damage to red blood cells     

Protective effect against oxidation of human low-density lipoprotein and plasmid DNA strand scission of Tamarind seed coat extract in vitro

Methanolic extract from seed coat of Thai Tamarindus indica L. containing polyphenol; procyanidins, (−)-epicatechin was studied in vitro for protective effect against Cu²⁺-induced human low-density lipoprotein (hLDL) oxidation and oxidative damage of plasmid DNA induced by Fenton reactant. LDL oxidation was monitored by formation of conjugated dienes, fluorescent products, protein carbonylation and thiobarbituric acid reactive substances (TBARS). Supercoiled DNA strand scission was evaluated by gel electrophoresis. The extract inhibited formation of all four products of oxidized LDL in a dose-dependent manner over 25-1000 ng/ml extracts. Furthermore, 1 mg/ml extract also protected supercoiled DNA strand in plasmid pBR322 against scission induced by Fenton-mediated hydroxyl radical similar to that found with reference antioxidant, 0.5 μg/ml Trolox. Thus, seed coat extract from Thai Tamarind shows antioxidant effects against in vitro Cu²⁺-mediated LDL oxidation and hydroxyl radical-induced supercoiled DNA damage. These results suggest that seed coat extract from Thai Tamarind may be useful for preventing LDL oxidation and DNA damage.     

Peroxynitrite induced discoloration of muscle foods

The objective of this research was to characterize the ability of peroxynitrite to cause the discoloration of meat using an in vitro oxymyoglobin system, a soluble fraction of beef muscle and minced muscle. Kinetic studies of the bolus addition of peroxynitrite (250 μM) to solutions of oxymyoglobin in phosphate buffer showed that oxidation occurred over the first 10 min producing 180 μM metmyoglobin and then slowed to the oxidation rate of the control. Addition of peroxynitrite (100-750 μM) to the soluble fraction of Longissimus dorsi muscle resulted in partial to complete discoloration of samples with 500-750 μM peroxynitrite resulting in 90-100% conversion of oxymyoglobin to metmyoglobin after 90 min. In minced L. dorsi samples, kinetic studies indicate that addition of 250 μM peroxynitrite resulted in a longer period of metmyoglobin formation than the in vitro experiment, lasting 40 min and resulting in the formation of 280 μM metmyoglobin. Antioxidants (ascorbic acid, glutathione, α-tocopherol and Trolox) were ineffective in preventing peroxynitrite-induced discoloration of minced meat, however ascorbic acid was able to partially restore color loss as the incubation period continued. The results indicate that peroxynitrite may be involved in the discoloration of muscle foods.     

Peroxynitrite: a potential initiator of lipid oxidation in food

Peroxynitrite is formed from the nearly diffusion limited reaction between nitric oxide and superoxide. This reactive nitrogen species has received intense interest in the biomedical field as an initiator of potentially harmful oxidation reactions. Peroxynitrite can also be viewed as an important pro-oxidant that affects food quality. Since most biological tissues used for foods contain systems that produce both nitric oxide and superoxide, conditions that enhance or suppress the formation of these precursors will influence the formation of peroxynitrite. The complex oxidative chemistry of peroxynitrite involves direct reactions with cellular constituents such as antioxidants, production of reactive species capable of initiating lipid oxidation, and catalyst-dependent nitration reactions which may redirect the reactivity of peroxynitrite to favor protein oxidations. Thus, peroxynitrite reactions in food may be deleterious, leading to a decline of quality parameters such as flavor, color, and functional properties.     

Oxidative stability of milk influenced by fatty acids, antioxidants, and copper derived from feed

Differences in the oxidative stability of milk from cows fed grass-clover silage or hay were examined in relation to fatty acid composition and contents of antioxidants and copper in the milk. The oxidation processes were induced by exposing the milk to fluorescent light. Protein oxidation was measured as an accumulation of dityrosine, whereas lipid oxidation was measured as an accumulation of lipid hydroperoxides as the primary oxidation product, and as the secondary oxidation products, pentanal, hexanal, and heptanal. No differences were found in the protein oxidation of the 2 types of milk measured as accumulation of dityrosine, but there was an increased accumulation of lipid hydroperoxides and hexanal in milk from cows fed grass-clover silage, compared with milk from cows fed hay. The higher degree of lipid oxidation in milk from cows fed grass-clover silage could not be explained from the concentration of α-tocopherol, carotenoids, uric acid, and copper in the milk. However, it was thought to be highly influenced by the significantly higher concentration of linolenic acid present in milk from cows fed grass-clover silage. A larger part of α-tocopherol and β-carotene was transferred from the feed to the milk when cows were fed grass-clover silage than when cows were fed hay as roughage. The significantly higher concentration of polyunsaturated fatty acids in milk from cows fed grass-clover silage may be important for the better transfer of α-tocopherol from the feed to the milk. Other circumstances, as the different conditions in the rumen may also play a role, due to the different types of roughages and their digestibility, or be related to the mechanisms during milk production for the higher yielding cows fed grass-clover silage.     

蓝莓皮提取物及油脂凝胶化对水飞蓟油氧化稳定性的影响

本文预期通过添加蓝莓皮提取物和油脂凝胶化来提高水飞蓟油的氧化稳定性,基于过氧化值(POV)和硫代巴比妥酸反应物(TBA)等化学方法与电子鼻技术和核磁共振技术(_¹H NMR)相结合,监测水飞蓟油氧化稳定性、气味和脂肪酸、色泽等变化。结果表明,蓝莓皮提取物能够有效的抑制水飞蓟油的氧化且具有剂量依赖关系,0.06%的蓝莓皮提取物对水飞蓟油的氧化抑制作用最佳;蓝莓皮提取物会影响水飞蓟油的气味但不影响其色泽;蓝莓皮提取物对水飞蓟油凝胶的色泽和气味均无影响,但制备成水飞蓟油脂凝胶明显提高了水飞蓟油氧化稳定性。     

Mulberry Anthocyanin Extracts Inhibit LDL Oxidation and Macrophage-Derived Foam Cell Formation Induced by Oxidative LDL

ABSTRACT:  Low-density lipoprotein (LDL) oxidation plays a role in atherosclerosis; therefore the lower the formation of oxidative LDL (oxLDL), the lower the occurrence of coronary heart diseases (CHD). Mulberry, the fruit of Morus alba L., is used effectively in Chinese medicines for prevention of CHD. However, the mechanism of this action is unclear. Two extracts, MWEs (mulberry water extracts) and MACs (mulberry anthocyanin-rich extracts), which exhibit antioxidative and anti-atherosclerogensis abilities in vitro . Data showed that MWEs and MACs were able to inhibit ( P < 0.05) the relative electrophoretic mobility (REM), ApoB fragmentation, and thiobarbituric acid reaction substances (TBARS) formation in Cu²⁺-mediated oxidation LDL. MWEs and MACs also had the ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging for reducing the formation of free radicals mediated by copper ions. Furthermore, we observed that MWEs and MACs could decrease ( P < 0.05) macrophage death induced by oxLDL. In addition, the MWEs and MACs also could inhibit ( P < 0.05) the formation of foam cells. Both MWEs and MACs showed a great ability of scavenging radicals, inhibition of LDL oxidation, and decrease in atherogenic stimuli in macrophages, while the efficacy of MACs is 10-fold greater than that of MWEs. It also demonstrated that anthocyanin components in mulberry extracts were regarded as the prevention of atherosclerosis.     

Effect of pH and Food Ingredients on the Stability of Egg Yolk Phospholipids and the Metal-Chelator Antioxidant Activity of Phosvitin

Egg yolk phosvitin has been previously shown to inhibit metal-catalyzed phospholipid oxidation. In this study, a phospholipid emulsion system was used to study the effect of pH and food ingredients on the antioxidant activity of phosvitin and the oxidative stability of yolk phospholipid. Oxidation of phospholipids was carried out at five different pH levels (3.0, 5.0, 5.7, 6.1, and 7.8). NaCl and freeze-dried egg albumen were incorporated into the pH 6.1 emulsion. Lipid oxidation was measured by the thiobarbituric acid (TBA) assay. Phospholipids were stable at pH 6.1 and 7.8. However, phosvitin was unable to inhibit Cu²⁺ catalysis at pH 7.8. Neither NaCl nor albumen affected the stability of phospholipids or the activity of phosvitin in inhibiting Fe²⁺ catalysis at pH 6.1.     

Comparison of Oxidative Stability of Sesame (Sesamum Indicum), Soybean (Glycine Max) and Mahua (Mee) (Madhuca Longifolia) Oils Against Photo-Oxidation and Autoxidation

Lipid oxidation is one of the major causes of food spoilage. This study was conducted to evaluate and compare the oxidative stability of sesame (Sesamum indicum), soybean (Glycine max) and mahua (Madhuca longifolia) against photooxidation and autoxidation. Stability of oils against photo-oxidation and autoxidation was determined by exposing the oils to florescent light over 28 days and storing the oils at an elevated temperature (60 °C) for 28 days, respectively. The level of oxidation was determined by measuring peroxide value (PV), thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and conjugated trienes (CT). Sesame oil exhibited the strongest oxidative stability against both photo-oxidation and autoxidation while Mahua oil exhibited the least stability highest both photo-oxidation and autoxidation as measured by primary oxidative products. However, Mahua oil showed the strongest stability against both photo-oxidation and autoxidation as measured by secondary oxidative products. In conclusion, higher oxidative stability was shown by the Mahua oil than sesame and soybean oils for photooxidation and autoxidation.     

Influence of anionic dietary fibers (xanthan gum and pectin) on oxidative stability and lipid digestibility of wheat protein-stabilized fish oil-in-water emulsion

The influence of two anionic dietary fibers (xanthan gum and pectin) on the oxidative stability and lipid digestibility of fish oil emulsions stabilized by wheat protein (gliadin) was investigated. Lipid oxidation was determined by measuring lipid hydroperoxides and TBARS of the emulsions during storage, while protein oxidation was measured using fluorescence spectroscopy. Lipid and protein oxidation was faster at pH 3.5 than at pH 7, which may have been due to increased iron solubility under acidic conditions. Xanthan gum inhibited lipid and protein oxidation, which was attributed to its ability to bind iron ions. Conversely, pectin promoted oxidation, which was attributed to the presence of endogenous transition metals in the polysaccharide ingredient. In vitro digestion was carried out to evaluate the digestibility of oil droplets in emulsions with or without polysaccharides. Both xanthan gum and pectin significantly increased the rate of lipid digestion, which was attributed to their ability to inhibit droplet aggregation under gastrointestinal conditions. These results have important implications for designing emulsion-based functional foods with improved oxidative stability and lipid digestibility.     

Effect of the Lycium barbarum polysaccharides administration on blood lipid metabolism and oxidative stress of mice fed high-fat diet in vivo

Epidemiological and experimental studies have suggested that high dietary fat intake of mice is associated with many physically degenerative diseases. Since oxidative stress and abnormal lipid metabolism have been speculated to be critical mechanisms underlying degenerative diseases, we hypothesized that a high-fat (HF) diet might induce oxidative stress or lipid oxidation and subsequently contribute to the high risk of some diseases such as cardiovascular and cerebrovascular ones. To test this hypothesis, male kunming mice were placed on either a HF diet or a normal laboratory diet for 30 consecutive days. This investigation demonstrated that blood fat [low density lipoprotein (LDL), total cholesterol (TC), triacylglycerols (TAG), high density lipoprotein (HDL)], blood sugar (blood glucose and liver glycogen) and oxidative stress (activities of antioxidant enzymes and levels of non-enzymic antioxidants) of mice fed high-fat diet (group II) were significantly increased or decreased (P < 0.05, P < 0.01) when compared with the control group (I). The present study revealed that HF diet induced oxidative stress and provided novel evidence regarding the link between high dietary fat and increased risk of degenerative diseases. The administration of Lycium barbarum polysaccharides did not show any effect on the body weight of the experimental mice, but significantly decreased the levels of LDL, TC, TAG, blood glucose and thiobarbituric acid reactive substances (TBARS) or increased the activities of antioxidant enzymes (P < 0.05, P < 0.01) when compared with mice in HF group (II). These findings were further supported by significantly increased non-enzymic antioxidants levels (P < 0.05, P < 0.01), suggesting that L. barbarum polysaccharides showed a noticeable inhibition against lipid oxidation induced by free radicals caused by HF diet intake (groups III, IV, V) on the basis of their antioxidant activities.     

Salvianolic acid B inhibits low‐density lipoprotein oxidation and neointimal hyperplasia in endothelium‐denuded hypercholesterolaemic rabbits

BACKGROUND: Atherosclerosis and restenosis are inflammatory responses involving free radicals and lipid peroxidation and may be prevented/cured by antioxidant‐mediated lipid peroxidation inhibition. Salvianolic acid (Sal B), a water‐soluble antioxidant obtained from a Chinese medicinal herb, is believed to have multiple preventive and therapeutic effects against human vascular diseases. In this study the in vitro and in vivo inhibitory effects of Sal B on oxidative stress were determined. RESULTS: In human aortic endothelial cells (HAECs), Sal B reduced oxidative stress, inhibited low‐density lipoprotein (LDL) oxidation and reduced oxidised LDL‐induced cytotoxicity. Sal B inhibited Cu²⁺‐induced LDL oxidation in vitro (with a potency 16.3 times that of probucol) and attenuated HAEC‐mediated LDL oxidation as well as reactive oxygen species (ROS) production. In cholesterol‐fed New Zealand White rabbits (with probucol as positive control), Sal B intake reduced Cu²⁺‐induced LDL oxidation, lipid deposition in the thoracic aorta, intimal thickness of the aortic arch and thoracic aorta and neointimal formation in the abdominal aorta. CONCLUSION: The data obtained in this study suggest that Sal B protects HAECs from oxidative injury‐mediated cell death via inhibition of ROS production. The antioxidant activity of Sal B may help explain its efficacy in the treatment of vascular diseases. Copyright © 2010 Society of Chemical Industry     

EFFECT OF VARIOUS ANTIOXIDANTS ON THE OXIDATIVE STABILITY OF ACID AND ALKALI SOLUBILIZED MUSCLE PROTEIN ISOLATES

Protein isolates prepared from cod ( Gadus morhua ) myofibrillar proteins using acid or alkali solubilization are susceptible to oxidative rancidity. Oxidation could be delayed by the exogenous addition of antioxidants. The objective of this research was to compare the efficacy of antioxidants such as δ-tocopherol, butylated hydroxyanisole (BHA) and propyl gallate, to inhibit oxidation in acid- and alkali- solubilized cod protein isolates. Oxidation was catalyzed using cod hemolysate. Oxidation of lipids was monitored by the measurement of thiobarbituric acid reactive substances and painty odor. Results showed that protein isolates prepared using the acid process was significantly ( P <  0.05) more susceptible to lipid oxidation than alkali-solubilized protein isolates. Regardless of pH treatments, the efficacy of various antioxidants decreased in the order propyl gallate  >  BHA  >  δ-tocopherol.

PRACTICAL APPLICATIONS

Research has shown that seafood available for human consumption is rapidly getting depleted and that many fish species may become extinct in the next half-century or so. Acid and alkali solubilization methods are recent but well-known techniques used for preparing protein isolates from under-utilized aquatic species and the by-products of seafood industry. Although numerous researchers have studied the use of acid and alkali processes on several sources of seafood, almost no research has been done on the use of antioxidants to protect protein isolates from lipid oxidation. In our research, we have studied the effect of various antioxidants on the oxidative stability of acid- and alkali-solubilized fish myofibrillar proteins. The results from this work will enable the seafood industry to properly identify the process and the type of antioxidants required for making muscle food products with increased oxidative stability.     

Oxidatively modified LDL and atherosclerosis: An evolving plausible scenario

Much evidence has accumulated that implicates the oxidative modification of low‐density lipoprotein (LDL) in the early stages of atherogenesis. The antioxidant nutrients alpha‐tocopherol, ascorbic acid, and beta‐carotene have been shown to inhibit in vitro LDL oxidation. In addition, they have been shown to increase the resistance of LDL to oxidation when given to animals and humans. Because plasma levels of these nutrients can be increased by dietary supplementation with minimal side effects, they may show promise in the prevention of coronary artery disease.     

Antioxidant activity of some phenolic constituents from green pepper (Piper nigrum L.) and fresh nutmeg mace (Myristica fragrans)

Antioxidant potential of phenolic compounds from green pepper (Piper nigrum L.) and lignans from fresh mace (Myristica fragrans) were evaluated for their ability to scavenge 1,1′-diphenyl-2-picrylhydrazyl (DPPH) radical, inhibit lipid peroxidation and protect plasmid DNA damage upon exposure to gamma radiation. EC₅₀ values of the major phenolic compounds of green pepper namely, 3,4-dihydroxyphenyl ethanol glucoside, 3,4-dihydroxy-6-(N-ethylamino) benzamide and phenolic acid glycosides were found to be 0.076, 0.27 and 0.12 mg/ml, respectively, suggesting a high radical scavenging activity of these phenolics. These results were further confirmed with cyclic voltammetry. Acetone extract of nutmeg mace and its subsequent TLC isolated fractions constituted mainly of lignans as revealed by GC–MS analysis. The major compounds were tentatively identified from their mass spectral fragmentation pattern. DPPH radical scavenging capacity of the acetone extract as well as its fractions was comparatively lower than that of green pepper phenolics. In contrast, these fractions had a greater ability to inhibit lipid oxidation than phenolics from pepper as revealed by β-carotene–linoleic acid assay. A DNA protecting role of these compounds even at doses as high as 5 kGy further suggested the potential use of green pepper and fresh nutmeg mace and their extracts as a nutraceutical in preventing oxidative damage to cells.