Hydroxyl Radical Scavenging Effect Research Articles

Antioxidative potential of folate producing probiotic Lactobacillus helveticus CD6.

Folate producing Lactobacillus sp. CD6 isolated from fermented milk showed 98% similarity with Lactobacillus helveticus based on 16S rRNA gene sequence analysis. It was found to produce a folic acid derivative 5-methyl tetrahydrofolate (5-MeTHF). The intracellular cell-free extract of strain demonstrated antioxidative activity with the inhibition rate of ascorbate autoxidation in the range of 27.5% ± 3.7%. It showed highest metal ion chelation ability for Fe(2+) (0.26 ± 0.06ppm) as compared to Cu(2+). The DPPH (α,α-Diphenyl-β-Picrylhydrazyl) radical scavenging activity for intact cells were found to be 24.7% ± 10.9% proved its antioxidative potential. Furthermore, it demonstrated 14.89% inhibition of epinephrine autoxidation, 20.9 ± 1.8μg cysteine equivalent reducing activity and 20.8% ± 0.9% hydroxyl radical scavenging effect. The strain was evaluated for probiotic properties as per WHO and FAO guidelines. It showed 90.61% survival at highly acidic condition (pH2.0), 90.66% viability in presence of synthetic gastric juice and 68% survivability at 0.5% bile concentration for 24h. It was susceptible to many antibiotics which reduces the prospect to offer resistance determinants to other organisms if administered in the form of probiotic preparations. It showed in vitro mucus binding and antimicrobial activity against enteric pathogens like Salmonella typhimurium (NCIM 2501), Streptococcus pyogenes (NCIM 2608), and Staphylococcus aureus (NCIM 5021) and moreover it showed non- hemolytic activity on sheep blood agar.

Potential of edaravone for neuroprotection in neurologic diseases that do not involve cerebral infarction

Edaravone was originally developed as a potent free radical scavenger and has been widely used to treat cerebral infarction in Japan since 2001. Several free radical scavengers have been developed and some of them have progressed to clinical trials for the treatment of cerebral infarction. One such scavenger, edaravone, has been approved by the regulatory authority in Japan for the treatment of patients with cerebral infarction. Of particular interest is the ability of edaravone to diffuse into the central nervous system in various neurologic diseases. Aside from its hydroxyl radical scavenging effect, edaravone has been found to have beneficial effects on inflammation, matrix metalloproteinases, nitric oxide production and apoptotic cell death. Concordantly, edaravone has been found to have neuroprotective effects in a number of animal models of disease, including stroke, spinal cord injury, traumatic brain injury, neurodegenerative diseases and brain tumors. The proven safety of edaravone following 9 years of use as a free radical scavenger suggests that it may have potential for development into an effective treatment of multiple neurologic conditions in humans.

Role of ascorbate in lung cellular toxicity mediated by light-exposed parenteral nutrition solution

Neonatal lung injury has been induced experimentally by infusion of multivitamin-containing light-exposed parenteral nutrition (PN) solutions. The objective was to explore the role of ascorbate in toxic effects of light-exposed PN on primary cultured foetal rat lung epithelial cells. Hydroperoxides were measured in 3% amino acid solutions at baseline, immediately after addition of either multivitamins or ascorbate alone (400 μg/mL) and again after a 24-h period of exposure to (or protection from) ambient light. Cellular toxicity was assessed by [C14]adenine release. Multivitamins or ascorbate alone increased hydroperoxides in PN, which was attenuated by light protection. Light-exposed PN containing multivitamins was more toxic to cells than baseline or light-protected PN. Exposure to ascorbate at concentrations both lower (< 5 μg/mL) and higher (> 1000 μg/mL) than normally contained in PN-induced oxidant-mediated cell death, as indicated by protective effects of hydroperoxide and hydroxyl radical scavengers. This study concludes that ascorbate generates toxic amounts of peroxide in PN solutions. The types and physiological importance of hydroperoxides induced by pro-oxidant effects of ascorbate require further evaluation in vivo.

Sodium salicylate is a novel catalytic inhibitor of human DNA topoisomerase II alpha

We have previously reported that pretreatment of human lymphoblastoid cells with the hydroxyl radical scavenger, N-acetyl cysteine, attenuates doxorubicin-induced DNA damage signalling through the ATM protein kinase. We sought to extend these studies to examine the effects of other hydroxyl radical scavengers in human breast cancer cells. Using MCF-7 cells, we observed that doxorubicin treatment triggered autophosphorylation of ATM on serine 1981 and the ATM-dependent activation of its downstream effectors p53, Chk2, and SMC1. Furthermore, we demonstrate that this effect was attenuated by pretreatment of cells with the hydroxyl radical scavengers sodium benzoate, sodium salicylate and, to a lesser extent, N-acetyl cysteine, but not Trolox™. Intriguingly, these effects were independent of doxorubicin's ability to redox cycle, were observed with multiple classes of topoisomerase II poisons, but did not represent a general damage-attenuating response. In addition, the observed effects were independent of the ability of sodium salicylate to inhibit cyclooxygenase-2 or NFκB. We demonstrate that sodium salicylate prevented doxorubicin-induced DNA double-strand break generation, which was attributable to inhibition of doxorubicin-stabilized topoisomerase IIα-DNA cleavable complex formation in vivo. Using topoisomerase IIα-DNA cleavage and decatenation assays, we determined that sodium salicylate is a catalytic inhibitor of topoisomerase IIα. Consistent with the observed inhibition of double-strand break formation, pretreatment of cells with sodium salicylate attenuated doxorubicin and etoposide cytotoxicity. These results demonstrate a novel mechanism of action for sodium salicylate and suggest that further study on the mechanism of topoisomerase II inhibition and the effects of related therapeutics on doxorubicin and etoposide cytotoxicity are warranted.

Antioxidant and metal chelating potential of the solvent fractions of Gelidiella acerosa, the red algae inhabiting South Indian coastal area

In vitro, antioxidant potential and metal chelating activity of various solvent fractions of Gelidiella acerosa were evaluated by different antioxidant assays like ferric reducing antioxidative power (FRAP) assay and scavenging activities for hydrogen peroxide, hydroxyl radical and nitric oxide. Among all the fractions, benzene showed the highest DPPH • radical, nitric oxide and hydrogen peroxide scavenging activity when compared to standard BHT with IC 50 values of 306.50 ± 3.04, 328.79 ± 14.25 and 275.43 ± 72.99 μg/ml respectively. Total antioxidative capacity and reducing power was found to be significantly higher in the dichloromethane fraction. Highest ferrous ion chelating activity was observed in ethyl acetate and benzene fractions. Dimethylsulfoxide fraction exerted the highest hydroxyl radical scavenging effect. Moreover, benzene and dichloromethane fraction showed the highest total polyphenolic content of 18.86 ± 0.27 and 17.69 ± 0.353 μg/mg of dry extract respectively. Preliminary cytotoxic studies suggest that benzene and dichloromethane fraction has no cytotoxic effect, hence, can be used as effective antioxidant for treating ROS mediated diseases.

Synthesis, crystal structures, DNA-binding properties, cytotoxic and antioxidation activities of several new ternary copper(II) complexes of N, N′-( p-xylylene)di-alanine acid and 1,10-phenanthroline

Three novel ternary copper(II) complexes, [Cu 2(phen) 2( l-PDIAla)(H 2O) 2](ClO 4) 2·2.5H 2O ( 1), [Cu 4(phen) 6( d, l-PDIAla)(H 2O) 2](ClO 4) 6·3H 2O ( 2) and [Cu 2(phen) 2( d, l-PDIAla)(H 2O)](ClO 4) 2·0.5H 2O ( 3) (phen = 1,10-phenanthroline, H 2PDIAla = N, N’-( p-xylylene)di-alanine acid) have been synthesized and structurally characterized by single-crystal X-ray crystallography and other structural analysis. Spectrometric titrations, ethidium bromide displacement experiments, CD (circular dichroism) spectral analysis and viscosity measurements indicate that the three compounds, especially the complex 3, strongly bind to calf-thymus DNA (CT-DNA). The intrinsic binding constants of the ternary copper(II) complexes with CT-DNA are 0.89 × 10 5, 1.14 × 10 5 and 1.72 × 10 5 M −1, for 1, 2 and 3, respectively. Comparative cytotoxic activities of the copper(II) complexes are also determined by acid phosphatase assay. The results show that the ternary copper(II) complexes have significant cytotoxic activity against the HeLa (Cervical cancer), HepG2 (hepatocarcinoma), HL-60 cells (myeloid leukemia), A-549 cells (pulmonary carcinoma) and L02 (liver cells). Investigations of antioxidation properties show that all the copper(II) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals.

Antioxidation and DNA-binding properties of binuclear Er(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde and four aroylhydrazines

The Er(III) complexes are prepared from Er(NO(3))(3).6H(2)O and Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde with four aroylhydrazines, including benzoylhydrazine, 2-hydroxybenzoylhydrazine, 4-hydroxybenzoylhydrazine and isonicotinylhydrazine, respectively. X-ray crystal and other structural analyses indicate that Er(III) and every ligand can form a binuclear Er(III) complex with nine-coordination and 1: 1 metal-to-ligand stoichiometry at the Er(III) centre. All the Er(III) complexes can bind to calf thymus DNA through intercalation with the binding constants at the order of magnitude 10(6) M(-1), and they may be used as potential anticancer drugs. All the Er(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals; however, complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals and complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals.

Synthesis, crystal structure, antioxidation and DNA-binding properties of the Ln complexes with 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldhyde-(benzoyl)hydrazone

Two lanthanide complexes (Ln = La, Pr) with a PMFP Schiff-base, 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldhyde-(benzoyl)hydrazone (H 2L) were synthesized and characterized. The crystal structure of the La complex was determined by single-crystal X-ray diffraction, the coordination polyhedron is a tricapped trigonal prism configuration with the nine-coordinate atoms composed of three nitrogens and six oxygens from three ligands. The complex crystallized in the monoclinic lattice with a space group P2/ c. Electronic absorption titration spectra, fluorescence titration spectra, EtBr competitive experiment, viscosity measurement and CD spectra indicate that all the complexes can strongly bind calf thymus DNA, presumably via groove binding and intercalation mechanism. Furthermore, investigations of antioxidation properties show that all the complexes have some scavenging effects for hydroxyl radicals.

Crystal structures, antioxidation and DNA binding properties of Dy(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde and four aroylhydrazines

X-ray crystal and other structural analyses indicate that Dy(III) and every ligand can form a binuclear Dy(III) complex with nine-coordination and 1:1 metal-to-ligand stoichiometry at the Dy(III) center. All the ligands and Dy(III) complexes can bind to Calf thymus DNA through intercalations with the binding constants at the order of magnitude 10 5–10 7 M −1, but Dy(III) complexes present stronger affinities to DNA than ligands. All the ligands and Dy(III) complexes can be used as potential anticancer drugs. All the ligands and Dy(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals but complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals and complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals.

Sonochemical destruction of nonylphenol: Effects of pH and hydroxyl radical scavengers

Nonylphenols are water-stable endocrine disrupting compounds that inhibit the growth of sewage bacteria in biological processes. The study describes the decomposition of 4-n-nonylphenol (NP) in water by 20 kHz ultrasound with emphasis on the impacts of pH, concentration and OH scavengers. It was found that the rate of degradation was accelerated by alkalinization, but more so by the addition of hydroxide alkalinity than carbonate. The addition of low doses of CO 3 2− and t-butyl alcohol as strong scavengers of OH was also found to accelerate the decomposition of NP. The observation was attributed to the generation of reactive CO 3 2− and CH 3 via pyrolysis of the additives in the cavity bubbles. The results also revealed that NP did not compete with OH scavenging agents when their relative concentration was low. In case of high frequency sonication (861 kHz) the competition was slightly effective (slowed down degradation) at an identical dose of t-butyl alcohol. The difference was attributed to shorter bubble life time at high frequencies leading to less violent/less energetic bubble collapse and lower yield of CH 3 .

Crystal structures, antioxidation and DNA binding properties of Eu(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxyaldehyde and three aroylhydrazines

Eu(III) and every newly synthesized ligand can form a binuclear Eu(III) complex with a 1:1 metal to ligand stoichiometry and nine-coordinate at Eu(III) center. Every ligand acts as a dibasic tetradentate ligand, binding to Eu(III) through the phenolate oxygen atom, nitrogen atom of quinolinato unit, the C=N group (methylene) and (-)O-C=N- group (enolized and deprotonated from O=C-NH- group) of the aroylhydrazine side chain. One DMF (N,N-dimethylformamide) molecule is binding orthogonally to the ligand-plane from one side to the metal ion, while another DMF and a nitrate anion (bidentate) are binding from the other. Dimerization of the monomeric unit occurs through the phenolate oxygen atoms leading to a central planar four-membered (EuO)(2) ring. On the other hand, all the ligands and Eu(III) complexes may be used as potential anticancer drugs, binding to Calf thymus DNA through intercalations at the order of magnitude 10(5)-10(7) M(-1). All the ligands and Eu(III) complexes are strong scavengers of hydroxyl radicals and superoxide radicals, but Eu(III) complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals than others, and Eu(III) complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals than others.

Synthesis, crystal structure, antioxidation and DNA binding properties of binuclear Ho(III) complexes of Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxyaldehyde and four aroylhydrazines

X-ray crystal and other structural analyses indicate that Ho(III) and every newly synthesized ligand can form a binuclear Ho(III) complex with a 1:1 metal-to-ligand stoichiometry by nine-coordination at the Ho(III) center. Every ligand acts as a dibasic tetradentate ligand, binding to Ho(III) through the phenolate oxygen atom, nitrogen atom of quinolinato unit and the C N group, −O–C N– group (enolized and deprotonated from O C–NH– group) of the aroylhydrazine side chain. One DMF molecule is binding orthogonally to the ligand-plane from one side to the metal ion, while another DMF and nitrate (bidentate) are binding from the other. Dimerization of this monomeric unit occurs through the phenolate oxygen atoms leading to a central planar four-membered (HoO) 2 ring. Investigations of DNA binding properties show that all the ligands and Ho(III) complexes can bind to Calf thymus DNA through intercalations with the binding constants at the order of magnitude 10 5–10 6 M −1, but Ho(III) complexes present stronger affinities to DNA than ligands. All the ligands and Ho(III) complexes may be used as potential anticancer drugs. Investigations of antioxidation properties show that all the ligands and Ho(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals but Ho(III) complexes show stronger scavenging effects for hydroxyl radicals than ligands.

Antioxidant and Antimicrobial Properties of Aqueous Extract from Dictyophora indusiata

The antioxidant and antimicrobial properties of hot water extract (WE) obtained from Dictyophora indusiata were investigated. The free radical scavenging ability of WE on DPPHwas 97.35% at 2 mg/ml concentration. The reduc- ing power of WE was moderate (1.22 at 2 mg/ml). Similarly, the WE displayed average scavenging effect on hydroxyl radical (52.28% at 2 mg/ml) and superoxide anion scavenging effect (48.64% at 2 mg/ml). However, the WE exhibited a very weak ferrous ion chelating effect of 18.56% at 2mg/ml concentration. Antimicrobial assay revealed that WE from D. indusiata can inhibit both bacteria and fungi used as indicators for antimicrobial effect at concentration of 200 mg/ml. The results suggest that WE possess good antioxidant and antimicrobial properties.

Crystal structures, antioxidation and DNA binding properties of Yb(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carbaldehyde and four aroylhydrazines

X-ray crystal and other structural analyses indicate that Yb(III) and all four newly synthesized ligands can form a binuclear Yb(III) complex with a 1:1 metal to ligand stoichiometry by octacoordination at the Yb(III) center. Investigations of DNA binding properties show that all the ligands and Yb(III) complexes can bind to Calf thymus DNA through intercalations with the binding constants at the order of magnitude 10(5)-10(7) M(-1), but Yb(III) complexes present stronger affinities to DNA than ligands. All the ligands and Yb(III) complexes may be used as potential anticancer drugs. Investigations of antioxidation properties show that all the ligands and Yb(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals but Yb(III) complexes show stronger scavenging effects for hydroxyl radicals than ligands.

Enhancing the electrochemical oxidation of acid-yellow 36 azo dye using boron-doped diamond electrodes by addition of ferrous ion

This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe 2+ (1 mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe 2+ concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe 2+ excess in the system.

Anti-photoaging activity and inhibition of matrix metalloproteinase (MMP) by marine red alga, Corallina pilulifera methanol extract

Matrix metalloproteinases (MMPs), a key component in photoaging of the skin due to exposure to ultraviolet A, appear to be increased by UV-irradiation-associated generation of reactive oxygen species (ROS). In this study, the alga Corallina pilulifera methanol (CPM) extract has been shown to exert a potent antioxidant activity and protective effect on UVA-induced oxidative stress of human dermal fibroblast (HDF) cell. Antioxidant evaluated by various antioxidant assays. These include reducing power, total antioxidant, DPPH radical scavenging, hydroxyl radical scavenging and protective effect on DNA damage caused by hydroxyl radicals generated. Further, the ROS level was detected using a fluorescence probe, 2′,7′-dichlorofluorescein diacetate (DCFH-DA), which could be converted to highly fluorescent dichlorofluorescein (DCF) with the presence of intracellular ROS on HT-1080 cells. Those various antioxidant activities were compared to standard antioxidants such as α-tocopherol. In addition, the in vitro activities of MMP-2 and MMP-9 in HDF cell were inhibited by C. pilulifera methanol extract dose dependently by using gelatin zymography method. The results obtained in the present study suggested that the C. pilulifera methanol extract may be a potential source of natural anti-photoaging.

Comparative study on composition and antioxidant properties of mint and black tea extract

SummaryThe antioxidant properties of plants could be correlated with oxidative stress defence in different human diseases. The present study was undertaken to evaluate and compare the antioxidant potential and the phytochemical composition in the aqueous extracts of mint leaves, black tea and black tea enriched with mint extract. All the three preparations exhibited free radical‐scavenging potential for nitric oxide (NO) radical, superoxide anion radical and hydroxyl radical, and the values were lesser than those of the antioxidants which acted as standards. In comparison, the mint extract exhibited higher free radical and NO scavenging effect. Hydroxyl radical and superoxide scavenging effects were more pronounced in tea with the mint extract, while the reducing power was exhibited more significantly by the black tea extract. The phytochemical compounds were identified and the total phenols and flavonoids were quantified and compared between these extracts.

A statistical experiment design approach for advanced oxidation of Direct Red azo-dye by photo-Fenton treatment

Advanced oxidation of an azo-dye, Direct Red 28 (DR 28) by photo-Fenton treatment was investigated in batch experiments using Box–Behnken statistical experiment design and the response surface analysis. Dyestuff (DR 28), H 2O 2 and Fe(II) concentrations were selected as independent variables in Box–Behnken design while color and total organic carbon (TOC) removal (mineralization) were considered as the response functions. Color removal increased with increasing H 2O 2 and Fe(II) concentrations up to a certain level. High concentrations of H 2O 2 and Fe(II) adversely affected the color and TOC removals due to hydroxyl radical scavenging effects of high oxidant and catalyst concentrations. Both H 2O 2 and Fe(II) concentration had profound effects on decolorization. Percent color removal was higher than TOC removal indicating formation of colorless organic intermediates. Complete color removal was achieved within 5 min while complete mineralization took nearly 15 min. The optimal reagent doses varied depending on the initial dyestuff dose. For the highest dyestuff concentration tested, the optimal H 2O 2/Fe(II)/dyestuff ratio resulting in the maximum color removal (100%) was predicted to be 715/71/250 (mg L −1), while this ratio was 1550/96.5/250 for maximum mineralization (97.5%).

Chemical Constituents, Antioxidative and Antimicrobial Activities of Essential Oil and Oleoresin of Tailed Pepper (Piper Cubeba L)

The antimicrobial and antioxidant potentials of hydrodistilled essential oil and oleoresin (obtained using acetone as a solvent) of tailed pepper were carried out by different techniques. The results obtained from antioxidant activity measurements of essential oil and oleoresin against mustard oil were measured for duration of 28 days in terms of peroxide, thiobarbituric acid, total carbonyl and p-anisidine values. The results obtained from butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) was similar to both the oleoresin and essential oil. In addition, the inhibitory action in linoleic acid system was studied by monitoring accumulation of peroxide concentration. The radical scavenging capacity of both essential oil and oleoresin on 2, 2'-diphenyl-1-picrylhydrazyl (DPPH) radical were (71.2%) and (69.77%) respectively at 25 µL/mL. It was relatively lower in comparison with synthetic antioxidants (BHA-96.41%; BHT- 95.91%). The results obtained from reducing power, chelating effect and hydroxyl radical scavenging effect was also supported the antioxidant of essential oil and oleoresin. The tailed pepper essential oil and oleoresin showed 100% mycelial zone inhibition against Penicillium viridicatum at 3000 and 2000 ppm respectively in the poison food method. It is interesting to note that the essential oil revealed 100% clear zone inhibition against Aspergillus flavus at all tested concentrations. The chemical characterization of tailed pepper essential oil by GC and GC-MS resulted in the identification of 44 components accounting for 97.8% of the oil.

Expression of the phycoerythrin gene of Gracilaria lemaneiformis (Rhodophyta) in E. coli and evaluation of the bioactivity of recombinant PE

Phycoerythrin (PE) is one of the most important proteins involved in light capturing during photosynthesis in red algae. Its potential biological activities had gained wide concerns. In the present study, tumor cytotoxic and hydroxyl radical assay were preformed to detect the bioactivity of recombinant PE. Recombinant plasmids pGEX-PE and pBGL were transformed into E. coli BL21 to make two recombinant strains BEX (pGEX-PE) and BGL (pBGL). PE expressing in BEX (pGEX-PE) was validated by SDS-PAGE and Western blotting analysis. SDS-PAGE analysis indicated that the PE-GST fusion protein was mostly inclusion bodies. Specific expression of PE was confirmed by Western blotting analysis. The recombinant E. coli BEX (pGEX-PE) cells were collected and sonicated. The supernatants were reserved for the tumor cytotoxic experiments. The result of tumor cytotoxic assay indicated that the supernatants containing PE had the activity of inhibiting the growth of Hela cells and with the increase of protein concentration, the inhibiting rate increased from 37.31% to 63.26%, which showed significant difference from the control. Hydroxyl radical scavenging effect was tested with supernatants of BEX (pGEX-PE) and BGL (pBGL) cell lysates treated with sonication and heating. For the sonication samples, the scavenging rates of the supernatants of BEX (pGEX-PE) and BGL (pBGL) cell lysates were significantly higher than the negative control BL21(pGEX-4T) (P<0.02), and the scavenging rates increased slowly following the increase of the protein content. For the heating samples, except for the 0.2 mg mL−1 BGL (pBGL) products, the scavenging effects of the supernatants of BEX (pGEX-PE) and BGL (pBGL) cell lysates were stronger than that of negative control BL21(pGEX-4T). However, the effect intensity was not positively correlated with the increase of the protein concentration. Though a partially decreased hydroxyl radical scavenging activity was led by heating, the biological activity was still retained and conspicuous. This research showed that phycoerythrin protein expressing in E. coli has the potential medical and sanitarian value.