Antioxidant activity and cytoprotective effect of kappa-carrageenan oligosaccharides and their different derivatives

Antioxidant activity of kappa-carrageenan oligosaccharides (OM) and their chemical modification derivatives was investigated employing various established in vitro systems, such as reducing power, iron ion chelation, and total antioxidant activity using beta-carotene-linoleic acid system. The oversulfated (SD), lowly (LAD), and highly acetylated derivatives (HAD) in reducing power assay, the phosphorylated derivative (PD) in metal chelating assay, and oversulfated and phosphorylated derivatives in total antioxidant activity assay exhibited antioxidant activity higher than that of carrageenan oligosaccharides. The results indicated that the chemical modification of carrageenan oligosaccharides can enhance their antioxidant activity in vitro. The protective effects of the carrageenan oligosaccharides and their chemically modified derivatives against H(2)O(2) and UVA (long-wave ultraviolet radiation) induced oxidative damage on rat thymic lymphocyte were investigated by measuring cell viability via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Thymic lymphocyte exposure to H(2)O(2) and UVA, a marked reduction in cell survival was observed, which was significantly prevented by carrageenan oligosaccharides and their derivatives (preincubated for 2h) at 66.7-2000 microg/mL. But both the carrageenan oligosaccharides and their different derivatives showed the similar protective effects on intracellular level. Taken together, these results suggest that carrageenan oligosaccharides and their derivatives show relevant antioxidant activity both in vitro and in a cell system.     

Synthesized oversulfated and acetylated derivatives of polysaccharide extracted from Enteromorpha linza and their potential antioxidant activity

Sulfated polysaccharide extracted from blue algae Enteromorpha linza is proved to possess excellent antioxidant activities. Two derivatives by means of oversulfated and acetylated coupling were synthesized and investigated their antioxidant activities including scavenging effect of superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals. And then the relationship between antioxidant activity and chemical characteristics was characterized. The results of chemical analysis and FT-IR showed that the modification of polysaccharide was successful. In addition, it was found that certain derivatives exhibited stronger antioxidant activity than raw material. They could serve as free-radical inhibitors or scavengers, acting possibly as primary antioxidants.     

In vitro antioxidant activities of acetylated, phosphorylated and benzoylated derivatives of porphyran extracted from Porphyra haitanensis

Porphyran extracted from red algae Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent antioxidant activities. In this study, we prepared the acetylated, phosphorylated and benzoylated derivatives of porphyran. And then the antioxidant activities of all the samples were investigated including scavenging effects of superoxide and hydroxyl radicals and reducing power. The results of chemical analysis and FT-IR spectrum showed the modifications of porphyran were successful. And in addition, we found that certain derivative exhibited stronger antioxidant activity than raw material. And the mechanism of the structure–function relationship of these derivatives needs to be attended to.     

Preparation of the different derivatives of the low-molecular-weight porphyran from Porphyra haitanensis and their antioxidant activities in vitro

Porphyran extracted from Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent antioxidant activities. In this study, we prepared one low-molecular-weight porphyran and its sulfated, acetylated, phosphorylated and benzoylated derivatives. Their antioxidant activities were investigated including scavenging effect of superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals. The results of chemical analysis and FT-IR spectrums showed the modification was successful. And in addition, we found that certain derivative exhibited stronger antioxidant activity than low-molecular-weight porphyran. The benzoylated derivative showed the most excellent antioxidant activity in three assays, so this derivative needs to be attended to.     

Enhanced immunostimulatory and antitumor activity of different derivatives of κ-carrageenan oligosaccharides from <Emphasis Type="Italic">Kappaphycus striatum</Emphasis>

Chemical modification of carbohydrates can lead to differences in their biological activities. We previously showed that κ-carrageenan oligosaccharides from Kappaphycus striatum have antitumor and immunomodulation effects on S180-bearing mice. In this study, we tested the hypothesis that different chemical modifications of carrageenan oligosaccharides enhance their activities. The mice inoculated with S180 cell suspension were treated p.o. with carrageenan oligosaccharides and their sulfated, acetylated, and phosphorylated derivatives (50, 100, and 200 μg g⁻¹) for 14 days. Transplantable tumor inhibition rate and macrophage phagocytosis, quantitative hemolysis of sheep red blood cells, lymphocyte proliferation, the activity of natural killer cells, production of interleukin-2, and tumor necrosis factor-α were also analyzed. As expected, treatment with different κ-carrageenan oligosaccharides derivatives resulted in an increase in tumor inhibition rate and macrophage phagocytosis and cellular immunity, especially on spleen lymphocyte proliferation. The sulfated derivative at the dose 200 μg g⁻¹ per day showed the highest antitumor activity with the 54.12% tumor weight inhibition and elicited an increase in nature killer cells activity up to 76.1% on S180-bearing mice, which were both significantly higher than the unmodified oligosaccharides. It suggested that chemical modification (especially sulfation) of carrageenan oligosaccharides can enhance their antitumor effect and boost their antitumor immunity.     

Synthesized phosphorylated and aminated derivatives of fucoidan and their potential antioxidant activity in vitro

Three sulfated polysaccharide derivatives (phosphorylated and aminated fucoidan) were synthesized, and their potential antioxidant activities were investigated employing various established in vitro systems. Two methods were used in phosphorylation fucoidan: polyphosphoric acid and POCl₃ method. Aminated fucoidan was prepared using the epichlorohydrin and ammonia water. All fucoidan derivatives possessed considerable antioxidant activity, and exhibited stronger antioxidant ability than fucoidan in certain tests. The phosphorylated fucoidan showed stronger hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. The mechanism on influence the antioxidant activity of samples of phosphate and amino group was indicated.     

Investigation of jumbo squid (Dosidicus gigas) skin gelatin peptides for their in vitro antioxidant effects

Peptides derived from tryptic hydrolysate of jumbo squid (Dosidicus gigas) skin gelatin were assessed for their antioxidant properties in different in vitro assay systems. The hydrolysate itself exhibited a strong lipid peroxidation inhibition and it was much higher than that of natural antioxidant, alpha-tocopherol. In addition, it could scavenge highly active free radicals in oxidative systems, in the order of hydroxyl and carbon-centered radicals. Two representative peptides with comparatively higher antioxidant potency were purified and characterized as Phe-Asp-Ser-Gly-Pro-Ala-Gly-Val-Leu (880.18 Da) and Asn-Gly-Pro-Leu-Gln-Ala-Gly-Gln-Pro-Gly-Glu-Arg (1241.59 Da). Furthermore, viability of radical-mediated oxidation-induced human lung fibroblasts was enhanced following the treatment of two peptides. However it did not exhibit substantial ion chelation, and we presumed that the observed radical scavenging potency of these peptides play a vital role for their strong antioxidant activity. Based on our results we suggest that hydrophobic amino acids present in peptide sequences contributed greatly for observed antioxidant activities.     

In vitro antioxidant activity of acetylated and benzoylated derivatives of polysaccharide extracted from Ulva pertusa (Chlorophyta)

The antioxidant activity of natural ulvan and its derivatives (acetylated and benzoylated ulvans) in vitro was determined, including scavenging activity against superoxide and hydroxyl radicals, reducing power, and chelating ability. Obvious differences in antioxidant activity between natural ulvan and its derivatives were observed, moreover, the antioxidant activity of acetylated and benzoylated ulvans was stronger than that of natural ulvan.     

Antiinflammatory and antioxidant evaluation of novel coumarin derivatives

Several coumarin derivatives have been reported to present multiple biological activities and especially antiinflammatory/antioxidant activities. Recently the synthesis and in vivo/in vitro anti-inflammatory/antioxidant activities of several new coumarin derivatives with a 7-azomethine linkage have been reported. In the present study these derivatives were further tested for their antioxidant ability. Some of them were found in vitro to inhibit lipid peroxidation and to strongly scavenge superoxide radicals. Compound 3 was found to potently inhibit cyclooxygenase-1 (COX-1) and the yeast-induced rat paw oedema. The most active compounds within the set were tested against adjuvant-induced arthritis. Compound 3 was found to significantly protect the rats from adjuvant-induced arthritis (when it is administered from the first day or when it is administered the fourteenth day, with the first symptoms of the disease). An attempt was made to delineate the possible mechanism of action of the studied compounds.     

Effect of acetylation on antioxidant and cytoprotective activity of polysaccharides isolated from pumpkin (Cucurbita pepo, lady godiva)

Acetylation of pumpkin (Cucurbita pepo, lady godiva variety) polysaccharide using acetic anhydride with pyridines as catalyst under different conditions was conducted to obtain different degrees of acetylation on a laboratory scale. Furthermore, antioxidant activities and cytoprotective effects of pumpkin polysaccharide and its acetylated derivatives were investigated employing various established in vitro systems. Results showed that addition of pyridine as catalyst could increase the degree of substitution, whereas volume of acetic anhydride had little effect. The acetylated polysaccharides in DPPH scavenging radical activity assay, superoxide anion radical activity assay and reducing power assay exhibited higher antioxidant activity than that of unmodified polysaccharide. H₂O₂-induced oxidative damages on rat thymic lymphocyte were also prevented by pumpkin polysaccharide and its acetylated derivatives and the derivatives presented higher protective effects. On the whole, acetylated polysaccharide showed relevant antioxidant activity both in vitro and in a cell system.     

Flavonoids from <Emphasis Type="Italic">Heliotropium subulatum</Emphasis> exudate and their evaluation for antioxidant,antineoplastic and cytotoxic activities II

The flavonoids are the largest group of phenolic compounds isolated from a wide range of higher plants. These compounds work as antimicrobials, anti-insect agents and protect plants from other types of biotic and abiotic stresses. Various researchers have suggested that flavonoids possessed antioxidant, antineoplastic and cytotoxic activities. The main objective of this study was to test dichloromethane fraction of resinous exudate of Heliotropium subulatum for their antioxidant, antineoplastic and cytotoxic activities, as well as to search new antioxidant and antineoplastic agents for pharmaceutical formulations. Five flavonoids were isolated from resinous exudate of this plant species and screened for their in vitro and in vivo antioxidant models (DPPH radical scavenging, reducing power, superoxide anion scavenging, metal chelating scavenging systems, catalase and lipid peroxidation), antineoplastic (Sarcoma 180), and cytotoxic (Chinese hamster V79 cells) activities. Tricetin demonstrated maximum antioxidant activity against both in vitro and in vivo experimental systems while galangin exhibited maximum inhibition (78.35%) at a dose of 10 µg/kg/day against Sarcoma 180. Similarly, it was found that galangin also showed highest activity (21.1 ± 0.15%) at a concentration of 70 µg/ml to Chinese hamster V79 cells. The observed results suggest that tricetin has a potential to scavenge free radicals in both in vitro and in vivo models while the galangin could be considered as antitumor and cytotoxic agent.     

Synthesized different derivatives of low molecular fucoidan extracted from Laminaria japonica and their potential antioxidant activity in vitro

Six low molecular fucoidan (DFPS) derivatives were synthesized successfully, and their potential antioxidant activities were investigated employing various established in vitro systems. All DFPS derivatives possessed considerable antioxidant activity, and had stronger antioxidant ability than DFPS in certain tests. The benzoylated DFPS (PHDF) showed strongest scavenging activity on superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, however, DFPS exhibited greatest reducing power. Available data suggested that substituted groups of DFPS played an important role on antioxidant activity, and the mechanism on influence the antioxidant activity of samples of substituted group was indicated.     

Chemical composition and antioxidant activities of different polysaccharides from the roots of Angelica dahurica

The total crude polysaccharides (CADPs), isolated from the roots of Angelica dahurica by H(2) O extraction, EtOH precipitation, and dialysis, and the four fractions ADP1, ADP2, ADP3, and ADP4, obtained by gel filtration of the CADPs, were analyzed to characterize their composition and evaluated for their antioxidant activity using different in vitro tests such as the malondialdehyde (MDA)-production, the ferrous ion (Fe(2+) )-chelating, and the HO(.) radical-scavenging assays. The predominant neutral monosaccharides in the four fractions were identified as arabinose, galactose, and glucose, while the composition and ratio of the monosaccharides were different between the fractions. The CADPs and its fractions were found to significantly inhibit lipid peroxidation, chelate Fe(2+) , and scavenge HO(.) radicals, indicating that these polysaccharides possessed antioxidant activity. Among the four fractions, ADP4 exhibited the strongest antioxidant activity, which was stronger than that of the control antioxidant vitamin E (Vit E). Taken together, the chemical composition of these polysaccharides might affect their antioxidant activity, and ADP4 could be explored as a source of potential novel natural antioxidants for food and pharmaceutical purposes.     

Dual antioxidant structures with potent anti-inflammatory,hypolipidemic and cytoprotective properties

Novel amide derivatives of trolox, 3,5-di-tert-butyl-4-hydroxybenzoic acid, (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid and cinnamic acid with cysteamine and l-cysteine ethyl ester were synthesised. In four cases, the disulfide derivatives were also isolated and tested. All compounds were examined for antioxidant activity, expressed as their ability to inhibit lipid peroxidation and to scavenge free radicals. They were found to demonstrate up to 17-fold better activity than that of the parent antioxidant acids. They could reduce acute inflammation up to 87%. The most active antioxidant compounds were further tested for their in vivo hypolipidemic effect, which ranged from 47% to 73%, and for their ability to protect the liver against oxidative toxicity caused by high paracetamol dose. The disulfide derivatives of 3,5-di-tert-butyl-4-hydroxybenzoic acid and cinnamic acid had no antioxidant activity and presented equal or lower anti-inflammatory effect than their thiol analogues, indicating that their molecular characteristics may not permit biological barrier penetration.     

不同取代度N-邻苯二甲酰壳聚糖抗氧化活性的研究

低聚壳聚糖与邻苯二甲酸酐酰化得到三种取代度不同的N-邻苯二甲酸酐酰低聚壳聚糖NPCOSA、NPCOSB和NPCOSC,取代度分别为0.330、.55和0.65。通过红外光谱对其结构进行表征。并考察了其抗氧化性能。结果表明:COS的抗氧化性能最强;随着取代度的增加,N-邻苯二甲酰低聚壳聚糖对超氧阴离子的清除能力逐渐升高;而对DPPH的清除能力以及还原能力呈逐渐下降趋势;对羟基自由基的清除顺序大小依次为NPCOSB>NPCOSA>NPCOSC,即NPCOSB清除羟基自由基的的能力最佳。     

New insights into the antioxidant activity of hydroxycinnamic and hydroxybenzoic systems: Spectroscopic,electrochemistry, and cellular studies

Abstract

A series hydroxycinnamic and gallic acids and their derivatives were studied with the aim of evaluating their in vitro antioxidant properties both in homogeneous and in cellular systems. It was concluded from the oxygen radical absorbance capacity-fluorescein (ORAC-FL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and cyclic voltammetry data that some compounds exhibit remarkable antioxidant properties. In general, in homogeneous media (DPPH assay), galloyl-based cinnamic and benzoic systems (compounds 7–11) were the most active, exhibiting the lowest oxidation potentials in both dimethyl sulfoxide (DMSO) and phosphate buffer. Yet, p-coumaric acid and its derivatives (compounds 1–3) disclosed the highest scavenging activity toward peroxyl radicals (ORAC-FL assay). Interesting structure–property– activity relationships between ORAC-FL, or DPPH radical, and redox potentials have been attained, showing that the latter parameter can be a valuable antioxidant measure. It was evidenced that redox potentials are related to the structural features of cinnamic and benzoic systems and that their activities are also dependent on the radical generated in the assay. Electron spin resonance data of the phenoxyl radicals generated both in DMSO and phosphate buffer support the assumption that radical stability is related to the type of phenolic system. Galloyl-based cinnamic and benzoic ester-type systems (compounds 9 and 11) were the most active and effective compounds in cell-based assays (51.13 ± 1.27% and 54.90 ± 3.65%, respectively). In cellular systems, hydroxycinnamic and hydroxybenzoic systems operate based on their intrinsic antioxidant outline and lipophilic properties, so the balance between these two properties is considered of the utmost importance to ensure their performance in the prevention or minimization of the effects due to free radical overproduction.     

Synthesis and antioxidant evaluation of novel silybin analogues

In this work, we evaluated the antioxidant properties of the eight novel silybin analogues for their capacity to scavenge free radicals including superoxide anion radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in vitro. Compound 7d demonstrated an excellent antioxidant effect in scavenging superoxide anion free radical with an IC50 value of 26.5 microM, while the IC50 of quercetin (the reference compound) was 38.1 microM. Compounds 7b, 7e, 7h showed certain scavenging activities for both types of free radicals.     

Hydroxycinnamates and their in vitro and in vivo antioxidant activities

Hydroxycinnamates are among the most widely distributed plant phenylpropanoids present in the free, conjugated-soluble and insoluble-bound forms. This review will focus on the occurrence, in vitro and in vivo antioxidant activities of ferulic, coumaric, caffeic and sinapic acids and their derivatives. Hydroxycinnamates are found in almost all food groups though they are abundant in cereals, legumes, oilseeds, fruits, vegetables and beverages and render antioxidant activity by scavenging hydroxyl radical, superoxide radical anion, several organic radicals, peroxyl radical, peroxinitrite and singlet oxygen, among others. Further, their antioxidant activity as chain breaking antioxidants and reducing agents is also notable. Ferulic acid and its derivatives such as ferulic acid ethyl ester, ferulic acid dehydrodimers, feruloyl glycosides and curcumin have demonstrated potent antioxidant activity in both in vitro and in vivo systems. Similarly, caffeic acid and some of its derivatives such as caffeic acid phenethyl ester, rosmarinic acid, and chlorogenic acid exhibit antioxidant activity. The highest antioxidant activity was observed for caffeic acid whereas p-coumaric acid had the least effect among major hydroxycinnamic acids. The importance of structural effects on the potency of antioxidant activity of hydroxycinnamates is discussed. While this review also shows the existence of substantial body of evidences for in vitro antioxidant activity of hydroxycinnamates, there is a clear gap for in vivo information, particularly for sinapic and p-coumaric acids and their derivatives. The role of grains, fruits, vegetables and red wine in disease risk reduction and health promotion could partly be attributed to their constituent hydroxycinnamates.     

Syntheses and evaluation of glucosyl aryl thiosemicarbazide and glucosyl thiosemicarbazone derivatives as antioxidant and anti-dyslipidemic agents

A series of N-per-O-acetyl-glucosyl arylthiosemicarbazide and thiosemicarbazone derivatives have been synthesized and evaluated for their in vivo anti-dyslipidemic and in vitro antioxidant activities. Among 16 compounds tested, 3 compounds showed potent anti-dyslipidemic activity and 6 compounds showed potent antioxidant and scavenger of oxygen free radicals activity.     

Antiinflammatory and antioxidant evaluation of novel coumarin derivatives

Several coumarin derivatives have been reported to present multiple biological activities and especially anti-inflammatory/antioxidant activities. Recently the synthesis and in vivo/in vitro anti-inflammatory /antioxidant activities of several new coumarin derivatives with a 7-azomethine linkage have been reported. In the present study these derivatives were further tested for their antioxidant ability. Some of them were found in vitro to inhibit lipid peroxidation and to strongly scavenge superoxide radicals. Compound 3 was found to potently inhibit cyclooxygenase-1 (COX-1) and the yeast-induced rat paw oedema. The most active compounds within the set were tested against adjuvant-induced arthritis. Compound 3 was found to significantly protect the rats from adjuvant-induced arthritis (when it is administered from the first day or when it is administered the fourteenth day, with the first symptoms of the disease). An attempt was made to delineate the possible mechanism of action of the studied compounds.