Evaluation of Superoxide Scavenging Activities of Hamamelis Extract and Hamamelitannin

Hamamelitannin, which is a component of bark extract of hamamelis (Hamamelis virginior L.), was found to be a potent scavenger of superoxide anion radicals. Superoxide anion scavenging activity of the compound was evaluated by ESR-spin trap method using DMPO (5,5′-dimethyl-1-pyrroline-N-oxide) as a spin trapping agent. The IC₅₀ value (the concentration producing 50% inhibition of superoxide anion radicals) of hamamelitannin was found to be 1.38 ± 0.06 μM much lower than that of ascorbic acid (23.31 ± 2.23 μM). Supporting the superoxide scavenging activity of hamamelitannin, the compound showed both suppresive ability against depolymelization of hyaluronic acid and protective ability against cytotoxicity induced by superoxide anion radicals. Hamamelitannin increased the survival rate of fibroblast to 85.5 ± 3.3%, compared with that of control (27.2 ± 4.3%).     

Antioxidant activities of phlorotannins isolated from Japanese Laminariaceae

The antioxidant activities of brown algal phlorotannins were evaluated using the inhibition of phospholipid peroxidation in the liposome system, and by determining radical scavenging activities against the superoxide anion and 1,1-diphenyl-2-picrylhydrazyl (DPPH). Oligomers of phloroglucinol (1,3,5-trihydroxybenzene), eckol (a trimer), phlorofucofuroeckol A (a pentamer), dieckol and 8,8′-bieckol (hexamers), isolated from the Laminarian brown algae Eisenia bicyclis, Ecklonia cava and Ecklonia kurome, showed potent inhibition of phospholipid peroxidation at 1 μM in the liposome system. The phlorotannins had significant radical scavenging activities against the superoxide anion (50% effective concentration values: 6.5–8.4 μM) and DPPH (50% effective concentration values: 12–26 μM), and were more effective compared to ascorbic acid and α-tocopherol. For the purpose of using phlorotannins as functional food ingredients, the antioxidant activity of a complex of crude phlorotannins and soybean protein was examined. The complex had a pronounced DPPH-radical scavenging activity. These results suggest that phlorotannins are potent anti-inflammatory substances, and that the Laminariaceous brown algae, which are abundant in phlorotannins, may be useful as a new functional foodstuff or supplement with anti-inflammatory activity.     

Evaluation of Superoxide Scavenging Activities of Hamamelis Extract and Hamamelitannin

Hamamelitannin, which is a component of bark extract of hamamelis (Hamamelis virginior L.), was found to be a potent scavenger of superoxide anion radicals. Superoxide anion scavenging activity of the compound was evaluated by ESR-spin trap method using DMPO (5,5'-dimethyl-1-pyrroline-N-oxide) as a spin trapping agent. The IC₅₀ value (the concentration producing 50% inhibition of superoxide anion radicals) of hamamelitannin was found to be 1.38 ± 0.06 μM much lower than that of ascorbic acid (23.31 ± 2.23 μM). Supporting the superoxide scavenging activity of hamamelitannin, the compound showed both suppresive ability against depolymelization of hyaluronic acid and protective ability against cytotoxicity induced by superoxide anion radicals. Hamamelitannin increased the survival rate of fibroblast to 85.5 ± 3.3%, compared with that of control (27.2 ± 4.3%).     

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 μM, while the IC₅₀ of quercetin (the reference compound) was 38.1 μM. Compounds 7b, 7e, 7h showed certain scavenging activities for both types of free radicals.     

Cyathuscavins A, B, and C, new free radical scavengers with DNA protection activity from the Basidiomycete Cyathus stercoreus

Three new polyketides, cyathuscavins A (1), B (2), and C (3) were isolated from the mycelium culture of Cyathus stercoreus. The structures of the compounds were elucidated on the basis of NMR and mass spectroscopic data. Antioxidant activities of the compounds were evaluated by the scavenging ability against ABTS⁺, DPPH, and superoxide anion radicals. Cyathuscavins A–C showed significant antioxidant activity comparable to those of reference antioxidants, BHA and Trolox. Cyathuscavins A–C protected supercoiled plasmid DNA from Fe²⁺/H₂O₂-induced breakage.     

Antioxidant and antibacterial activities of lichen <Emphasis Type="Italic">Usnea ghattensis</Emphasis><Emphasis Type="Italic">in vitro</Emphasis>

Various solvent extracts of the lichen Usnea ghattensis showed good antioxidant activity. A methanol extract prevented lipid peroxidation by 87% followed by 65% in Trolox at 20 μg/ml. It also showed superoxide anion scavenging activity and free radical scavenging activity 56% and 73%, respectively. The known antioxidants butylated hydroxytoluene (BHT), butylated hydroxyanisol (BHA) and quercetin at similar concentrations showed superoxide anion scavenging activity of 68, 59 and 47% and free radical scavenging activity 83, 77 and 69%, respectively. In addition, these extracts were inhibitory against Bacillus licheniformis, Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus with MIC values of 5–10 μg/ml.Received after revisions 10 May 2005     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

Abstract

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO^?), superoxide anion (O₂^??), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC₅₀ = 2.3 ± 0.2 and 1.9 ± 0.1 μg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 ± 0.2 and 0.2 ± 0.1 μg/ml, respectively), and also showed a considerable antioxidant activity against O₂^??(87.3 ± 0.1 and 73.1 ± 0.4 μg/ml, respectively) and DPPH radicals (55.4 ± 0.3 and 38.3 ± 0.4 μg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl₄ significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl₄ in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

Superoxide dismutase and hydrogen peroxide formation in Campylobacter sputorum subspecies bubulus

Cell-free extracts of Campylobacter sputorum subspecies bubulus contained superoxide dismutase. The enzyme was located in the cytoplasmic fraction and insensitive to cyanide. After centrifuging a cell-free extract at 144000 x g for 1.5 h the total activity in the supernatant fraction was threefold higher than in the crude cell-free extract. The pellet fraction thus obtained was shown to have a lowering effect on superoxide dismutase activities from different sources in the assay method used here. C. sputorum responded to a raised oxygen tension in the culture by an increase in the superoxide dismutase activity. The ability to produce superoxide anion radicals (O₂ ^-·) during oxidation of formate and lactate was demonstrated. Furthermore C. sputorum was found to produce H₂O₂ while oxidizing formate. In experiments in which the reduction of cytochrome c by formate was followed, step-wise kinetics were observed. One of the steady states then obtained was attributed to the oxidizing action of H₂O₂, because it was abolished by the addition of catalase and lengthened by H₂O₂ added in addition to H₂O₂ formed as a product of formate oxidation. An overall reaction for formate oxidation by C. sputorum is discussed.Abbreviations O₂ ^-· superoxide anion radical - NBT p-nitro blue tetrazolium chloride - ABTS 2,2-azino-di-[3-ethylbenzthiazoline sulfonate (6)] - TL-medium tryptose-lactate medium     

Characterization of oxygen free radicals generated during vanadate-stimulated NADH oxidation

The oxidation of NADH and accompanying reduction of oxygen to H₂O₂ stimulated by polyvanadate was markedly inhibited by SOD and cytochrome c. The presence of decavanadate, the polymeric form, is necessary for obtaining the microsomal enzyme-catalyzed activity. The accompanying activity of reduction of cytochrome c was found to be SOD-insensitive and therefore does not represent superoxide formation. The reduction of cytochrome c by vanadyl sulfate was also SOD-insensitive. In the presence of H₂O₂ all the forms of vanadate were able to oxidize reduced cytochrome c, which was sensitive to mannitol, tris and also catalase, indicating H₂0₂-dependent generation of hydroxyl radicals. Using ESR and spin trapping technique only hydroxyl radicals, but not superoxide anion radicals, were detected during polyvanadate-dependent NADH oxidation.     

Superoxide dismutase–mimicking activities of dinuclear Cu(II) complexes with ligands containing a tetrathioether-tetraamino moiety

The superoxide scavenging activities of copper(II) complexes with the ligands, 6,6′-methylene-bis(5′-amino-3′,4′-benzo-2′-thiapentyl)-1,11-diamino-2,3:9,10-dibenzo-4,8-dithiaundecane (H₄L), and 6,6′-bis(5′-amino-3′,4′-benzo-2′-thiapentyl)-1,11-diamino-2,3:9,10-dibenzo-4,8-dithiaundecane (H₄L′), were investigated by xanthine–xanthine oxidase (X/XO) assays using nitroblue tetrazolium (NBT) as indicator molecule, and the results were compared with respect to the particular type of anion (ClO·4, Cl^·, NO·3) on the apical site of the copper(II) complexes. All of the complexes inhibited the reduction of NBT by superoxide radicals, with the [Cu₂(L′)](ClO₄)₂ complex exhibiting the highest scavenging activity against superoxide radicals among the complexes examined. The catalytic efficiency of the complexes for dismutation of superoxide radicals depends on the particular anion liganded to Cu(II) ion in the complexes, and the order of potency was observed to be ClO₄ > Cl > NO·3 in phosphate buffer at pH 7.40. The Cu(II)-H₄L′ complexes had the lowest IC₅₀ and catalytic rate constant values indicating that the distorted geometry of the Cu(II)-H₄L′ complexes influence their catalytic activities for dismutation of superoxide radicals more efficiently. The difference in the activities of the complexes toward superoxide radicals can also be attributed to the nature of the anions on the apical site of the copper(II) complexes and the superoxide dismutase-like activity. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 12: 53–59, 1998     

Superoxide radicals scavenging and xanthine oxidase inhibitory activity of magnesium lithospermate B from Salvia miltiorrhiza

In this study we investigated the superoxide radicals scavenging effect and xanthine oxidase inhibitory activity by magnesium lithospermate B, which was originally isolated from the roots of Salvia miltiorrhiza (also named Danshen or Dansham), an important herb in Oriental medicine. Superoxide radicals were generated both in β-NADH/PMS system and xanthine/ xanthine oxidase system. Magnesium lithospermate B significantly inhibited the reduction of NBT induced by superoxide radicals with an IC₅₀ of 29.8 μg/mL and 4.06 μg/mL respectively in the two systems. Further study suggested that magnesium lithospermate B can directly inhibit xanthine oxidase and exhibits competitive inhibition. Magnesium lithospermate B was also found to have the hypouricemic activity in vivo against potassium oxonate-induced hyperuricaemia in mice. After oral administration of magnesium lithospermate B at doses of 10, 20 and 30 mg/kg, there was a significant decrease in the serum urate level when compared to the hyperuricemia control. In addition, magnesium lithospermate B significantly protected HL-60 cells from superoxide radicals-induced apoptosis in the xanthine/ xanthine oxidase reactions. This study provided evidence that magnesium lithospermate B exhibits direct superoxide radicals scavenging and xanthine oxidase inhibitory activity.     

Antioxidant activity of mycosporine-like amino acids isolated from three red macroalgae and one marine lichen

Several standard in vitro assays were performed in order to determine the potential antioxidant capabilities of purified aqueous extracts of the mycosporine-like amino acids (MAAs), porphyra-334 plus shinorine (P-334 + SH), isolated from the red alga Porphyra rosengurttii, asterina-330 plus palythine (AS-330 + PNE), from the red alga Gelidium corneum, shinorine (SH), from the red alga Ahnfeltiopsis devoniensis, and mycosporine -glycine (M-Gly), isolated from the marine lichen Lichina pygmaea. The scavenging potential of hydrosoluble radicals (ABTS⁺ decolorization method), the antioxidant activity in lipid medium (β-carotene/ linoleate bleaching method) and the scavenging capacity of superoxide radicals (pyrogallol autooxidation assay) were evaluated. In terms of scavenging of hydrosoluble radicals, the antioxidant activity of all MAAs studied was dose-dependent and it increased with the alkalinity of the medium (pH 6 to 8.5). M-Gly presented the highest activity in all pH tested; at pH 8.5 its IC₅₀ was 8-fold that of L-ascorbic acid (L-ASC) followed by AS-330 + PNE while P-334 + SH and SH showed scarce activity of scavenging of hydrosoluble free radicals. AS-330 + PNE showed high activity for inhibition of β-carotene oxidation relative to vitamin E and superoxide radical scavenging whilst the activity of P-334 +SH and SH were moderate. According to these results, the potential of MAAs in photoprotection can be considered high due to a double function: (1) UV chemical screening with high efficiency for UVB and UVA regions of the solar spectrum, and (2) their antioxidant capacity.     

Studies on the antioxidant activities of some new chromone compounds

Recent reviews evidence that the naturally occurring compounds containing the chromone skeleton exhibit antiradical activities, providing protection against oxidative stress. The antioxidant activities of 13 new synthesized chromonyl‐2,4‐thiazolidinediones, chromonyl‐2,4‐imidazolidinediones and chromonyl‐2‐thioxoimidzolidine‐4‐ones were evaluated using in vitro antioxidant assays, including superoxide anion radical (), hydroxyl radical (), 2,2‐diphenyl‐1‐picryl‐hydrazyl free radical (DPPH^?) scavenging capacity and total antioxidant capacity ferric ion reducing activity. Superoxide anion radical was produced using potassium superoxide/18‐crown‐6‐ether dissolved in dimethylsulfoxide, and the Fenton‐like reaction (Fe(II) + H₂O₂) was a generator of hydroxyl radicals. Chemiluminescence, spectrophotometry, electron paramagnetic resonance (EPR) and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) as the spin trap were the measurement techniques. The results showed that the majority of the chromone derivatives tested showed a strong scavenging effect towards free radicals, similar to the chemiluminescence reaction with superoxide anion radical with a high activity, inhibition of the DMPO‐OOH radical EPR signal (24–58%), the DMPO‐OH radical EPR signal (4–75%) and DPPH radical EPR signal (6–100%) at 1 mmol/L. Several of the examined compounds exhibited the high reduction potentials. The results obtained show that the new synthesized chromone derivatives may directly scavenger reactive oxygen species and thus may play a protective role against oxidative damage. Copyright © 2014 John Wiley & Sons, Ltd.     

Evaluation of antioxidant activity of <Emphasis Type="Italic">Melothria maderaspatana in vitro</Emphasis>

In this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.     

4种珍稀食用菌水提物的抗氧化活性研究

用DPPH自由基清除法、羟基自由基清除法和超氧阴离子自由基清除法对4种珍稀食用菌灵芝、云芝、茶树菇、松茸的水提物进行抗氧化活性评价,为更好评价其抗氧化活性,以维生素C作为阳性对照。实验结果显示：4种食用菌水提物具有不同程度的抗氧化活性。云芝对DPPH自由基的清除能力最强,其IC₅₀值为1.46 mg/mL,维生素C清除DPPH自由基的IC₅₀为0.046 mg/mL;茶树菇对清除羟基自由基的清除能力最强,其IC₅₀值为1.41 mg/mL,云芝和松茸也有较强清除羟自由基能力,其IC₅₀值分别为1.56、1.57 mg/mL,三者的清除能力均明显优于阳性对照样品,维生素C清除羟自由基的IC₅₀为2.41 mg/mL;灵芝和云芝有较强清除超氧阴离子自由基能力,其IC₅₀值分别为124.48、138.28 mg/mL。     

Investigations on Antioxidant,Antiproliferative and COX‐2 Inhibitory Potential of Alkaloids from Anthocephalus cadamba (Roxb.) Miq. Leaves

In the present study, an ayurvedic medicinal plant, Anthocephalus cadamba (Roxb .) Miq . commonly known as ‘Kadamb’ was explored for its potential against oxidative stress and cancer. The fractions namely AC‐4 and ACALK (alkaloid rich fraction) were isolated from A. cadamba leaves by employing two different isolation methods and evaluated for their in vitro antioxidant and antiproliferative activity. The structure of the isolated AC‐4 was characterized tentatively as dihydrocadambine by using various spectroscopic techniques such as ESI‐QTOF‐MS, ¹H‐ and ¹³C‐NMR, DEPT, COSY, HMQC, and HMBC. Results of various antioxidant assays viz. 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ABTS cation radical, superoxide anion radical scavenging, and plasmid nicking assay demonstrated that both the fractions viz. AC‐4 and ACALK possess ability to scavenge DPPH, ABTS radicals and effectively protected plasmid pBR322 DNA from damage caused by hydroxyl radicals. Further, when both fractions were evaluated for their potential to suppress growth of HeLa and COLO 205 cells, only ACALK fraction showed antiproliferative effects. ACALK exhibited GI₅₀ of 205.98 and 99.54 μg/ml in HeLa and COLO 205 cell lines, respectively. Results of Hoechst staining in cervical carcinoma (HeLa) cells confirmed that ACALK induced cell death in HeLa cells via apoptotic mode. Both the fractions also inhibited COX‐2 enzyme activity.     

In vitro antioxidant and antibacterial properties of hydrolysed proteins of delimed tannery fleshings: comparison of acid hydrolysis and fermentation methods

Proteins in delimed tannery fleshings were fermentatively hydrolysed using Enterococcus faecium NCIM5335 and also hydrolysed using mild organic acids (formic acid and propionic acid). The liquor portion containing hydrolysed proteins was spray dried, in both the cases, to obtain a powder. The spray dried powder was evaluated for in vitro antioxidant activities with respect to scavenging different free radicals and antibacterial properties against nine different pathogens. Fermentation and acid hydrolysates scavenged 83 and 75.3% of 2,2-azino-bis-3-ethyl-benzthiazoline-6-sulphonic acid (ABTS) radicals, respectively, at a protein concentration of 0.25 mg. Further, fermentation hydrolysate showed higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of 59% as compared to 56% scavenging by acid hydrolysate at a protein concentration of 5 mg. Acid hydrolysate exhibited lesser (82.3%) peroxy radical scavenging compared to hydrolysate from fermentation (88.2%) at a protein concentration of 10 mg. However, acid hydrolysate exhibited higher (89.2%) superoxide anion scavenging while its fermentation counterpart showed lower activity (85.4%) at 2.5 mg hydrolysate protein. Well as superoxide anion scavenging properties. All the in vitro antioxidant properties exhibited dose dependency. Fermentation hydrolysate exhibited maximum antagonistic activity against Salmonella typhi FB231, from among host of pathogens evaluated. Both the hydrolysates have potential to be ingredients in animal feeds and can help reduce oxidative stress in the animals.     

Radical scavenging ability of some compounds isolated from Piper cubeba towards free radicals

The purpose of this study was to identify the antioxidant activity of 16 compounds isolated from Piper cubeba (CNCs) through the extent of their capacities to scavenge free radicals, hydroxyl radical (HO^?), superoxide anion radical () and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH^?), in different systems. Electron paramagnetic resonance (EPR) and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide, DMPO, as the spin trap, and chemiluminescence techniques were applied. Using the Fenton‐like reaction [Fe(II) + H₂O₂], CNCs were found to inhibit DMPO? OH radical formation ranging from 5 to 57% at 1.25 mmol L^?1 concentration. The examined CNCs also showed a high DPPH antiradical activity (ranging from 15 to 99% at 5 mmol L^?1 concentration). Furthermore, the results indicated that seven of the 16 tested compounds may catalyse the conversion of superoxide radicals generated in the potassium superoxide/18‐crown‐6 ether system, thus showing superoxide dismutase‐like activity. The data obtained suggest that radical scavenging properties of CNCs might have potential application in many plant medicines. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and antioxidant activity evaluations of melatonin-based analogue indole-hydrazide/hydrazone derivatives

Melatonin (MLT) is a hormone synthesized from the pineal gland. It is a direct scavenger of free radicals, which is related to its capability to defend cells from oxidative stress. Recently MLT-related compounds are under investigation to establish which exhibit the maximum activity with the lowest side effects. In this study 5-chloroindole hydrazide/hydrazone derivatives were synthesized from 5-chloroindole-3-carboxaldehyde and phenyl hydrazine derivatives. All the compounds characterized and in vitro antioxidant activity was investigated against MLT and BHT. Most of the compounds showed strong inhibitory effect on the superoxide radical scavenging assay at 1?mM concentration (79 to 95%). Almost all the tested compounds possessed strong scavenging activity against the DPPH radical scavenging activity with IC₅₀ values (2 to 60 µM). Lastly, compound 1j revealed stronger inhibitory activity against MLT in the LP inhibitory assay at 0.1mM concentration (51%) while the rest of the compounds showed moderate inhibition.     

Functional properties of dioscorin, a soluble viscous protein from Japanese yam (Dioscorea opposita thunb.) tuber mucilage Tororo

A soluble viscous protein was purified from yam (Dioscorea opposita Thunb.) tuber mucilage tororo by chromatographic steps, and its functional properties were estimated. The purified dioscorin having the molecular weight of about 200 kDa exhibited high scavenging activities against hydroxyl radicals (IC50 = 195.1 microg/ml) and superoxide anion radicals (IC50 = 92.7 microg/ml). Moreover, it showed extremely high angiotensin I-converting enzyme inhibitory activity (IC50 = 41.1 microg/ml). The results suggested that yam D. opposita tuber has a wide spectrum of strong antioxidative and antihypertensive activities and it could be utilized as a source of natural antioxidant.