• Journal of Preventive Medicine and Public Health
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• v.34 no.1
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• pp.41-46
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• 2001

Objectives : To investigate the effects of particulate matter (PM), a marker of environmental pollution derived from combustion sources, on lung epithelial cells (A549) and macrophage (RAW 264.7). Methods : The production of reactive radicals from lung cells, the lipid peroxidation of cell membrane, and the cytotoxicity of PM were measured using an in vitro model. The results were compared with a control group. Results : The presence of PM significantly increased the production of reactive oxygen species and reactive nitrogen species with time and in a dose dependent pattern and also increased the malondialdehyde concentration in lung epithelial cells. The cytotoxicity of PM was increased with increasing concentration of PM. Conclusions : It has been suggested that urban particulate matter causes an inflammatory reaction in lung tissue through the production of hydroxyl radicals, nitric oxides and numerous cytokines. The causal chemical determinant responsible for these biologic effects are not well understood, but the bioavailable metal in PM seems to determine the tonicity of inhaled PM.

• Environmental Engineering Research
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• v.10 no.3
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• pp.138-143
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• 2005

Laboratory batch experiments were conducted to evaluate the Fenton degradation rates of phenanthrene. Fenton reactions for the degradation of phenanthrene were carried out with aqueous and slurry phase, to investigate the effects of sorption of phenanthrene onto solid phase. Various types of surfactants and electrolyte solutions were used to evaluate the effects on the phenanthrene degradation rates by Fenton's reaction. A maximum 90% removal of phenanthrene was achieved in aqueous phase with 0.9% of $H_2O_2$ and 300 mg/L of $Fe^{2+}$ at pH 3. In aqueous phase reaction, inhibitory effects of synthetic surfactants on the removal of phenanthrene were observed, implying that surfactant molecules acted as strong scavenger of hydroxyl radicals. However, use of $carboxymethyl-{\beta}-cyclodextrin$ (CMCD), natural surfactant, showed a slight enhancement in the degradation of phenanthrene. It was considered that reactive radicals formed at ternary complex were located in close proximity to phenanthrene partitioned into CMCD cavities. It was also show that Fenton degradation of phenanthrene were greatly enhanced by addition of NaCl, indicating that potent radical ion ($OCI^-$) played an important role in the phenanthrene degradation, although chloride ion might be acted as scavenger of radicals at low concentrations. Phenanthrene in slurry phase was resistant to Fenton degradation. It might be due to the fact that free radicals were mostly reacting with dissolved species rather than with sorbed phenanthrene. Even though synthetic surfactants were added to increase the phenanthrene concentration in dissolved phase, low degradation efficiency was obtained because of the scavenging of radicals by surfactants molecules. However, use of CMCD in slurry phase, showed a slight enhancement in the phenanthrene degradation. As an alternative, use of Fenton reaction with CMCD could be considered to increase the degradation rates of phenanthrene desorbed from solid phase.

• Korean Journal of Plant Resources
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• v.22 no.6
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• pp.489-497
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• 2009

In this study, we evaluated and compared the protective effects of two major constituents, baicalein and baicalin, against oxidative DNA and cell damages caused by hydroxyl radical. Antioxidant properties were evaluated using DPPH and hydroxyl radicals scavenging assays and $Fe^{2+}$ chelating assay. ${\varphi}X$ 174 RFI plasmid DNA and intracellular DNA migration assay were used to evaluate the protective effect against oxidative DNA damage. Also, MTT and lipid peroxidation assays were used to evaluate their protective effects against oxidative cell damage. Both baicalein and baicalin prevented intracellular DNA and cells from oxidative damage caused by hydroxyl radical via antioxidant activities. Baicalein demonstrated a stronger antioxidant activity in scavenging DPPH radicals and chelating $Fe^{2+}$ while baicalin scavenged hydroxyl radicals more efficiently. The differences in the level of baicalein and baicalin pose a different pathological pathway for each. The antioxidant activity of baicalin was due to its ability to scavenge hydroxyl radical whilst baicalein was a stronger $Fe^{2+}$ chelator. Further investigation to compare the molecular mechanisms of antitumor activities of baicalein and baicalin is vital to anticancer research.

• Natural Product Sciences
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• v.7 no.3
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• pp.72-75
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• 2001

The antioxidant activity of roasted defatted perilla (Perilla frutescens) seed was determined by measuring its radical scavenging effect on 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals, inhibitory activity on total reactive oxygen species generation in kidney homogenates using 2',7'-dichlorodihydro-fluorescein diacetate, and scavenging effect on authentic peroxynitrites. The methanolic extract of roasted defatted perilla seed showed strong scavenging activity in both DPPH and peroxynitrite radicals, and thus fractionated with several solvents. The antioxidant activity potential of the individual fraction was in the order of ethyl acetate>n-butanol>dichloromethane>water>n-hexane fraction. The ethyl acetate soluble fraction exhibiting strong antioxidant activity was further purified by repeated silica gel and Sephadex LH-20 column chromatography. Luteolin was isolated as one of the active principles from the ethyl acetate fraction, together with the inactive chrysoeriol and apigenin.

• Journal of Photoscience
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• v.9 no.2
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• pp.382-384
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• 2002

When illuminated with strong visible light, the reaction center Dl protein of photo system II is photodamage and degraded. Reactive oxygen species and endogenous cationic radicals generated by photochemical reactions are the cause of the damage to the Dl protein. Recently we found that the photodamaged Dl protein cross-links with the surrounding polypeptides such as D2 and CP43 in photosystem II. As the cross-linking reaction is dependent on the presence of oxygen, reactive oxygen species are suggested to be involved. Among the reactive oxygen species examined, ？ OH was most effective in the formation of the cross-linked products. These results indicate that the cross-linking is mostly due to ？ OH generated at photosystem II. The cross-linking site of the Dl protein is not known. As several tyrosine residues exist at the D­E loop of the Dl protein, there is a possibility that di-Tyr is formed between the D­E loop of the Dl protein and surrounding polypeptides during the strong illumination. Therefore, we examined the formation of di-Tyr using the monoclonal antibody against di-Tyr under excess illumination of the photosystem II membranes. The results obtained here suggest that no di-Tyr is formed during the excess illumination of photosystem II.

• Polymer(Korea)
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• v.30 no.5
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• pp.437-444
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• 2006

Reactive hydroxypropyl methylcellulose phthalate (reactive HPMCP) was synthesized by using a stepwise urethane reaction with isophorone diisocyanate (IPDI) and 2-hydroxyethyl moth acrylate (HEMA). Molecular weight, acid number, and critical micelle concentration (CMC) of the synthesized reactive HPMCP and pristine HPMCP were measured and used as a polymeric surfactant in the emulsion polymerizations of styrene. In the preparation of HPMCP-hybrid poly styrene nanoparticles, 6, 9, 12, 18, and 24 wt% of HPMCPs were introduced, and the maximum rate of polymerization ($R_{p,max}$), the average number of radicals per particle (n), particle size distribution were investigated. In addition, core - shell morphology of the nanoparticles were observed by using TEM and their thermal stabilities were measured by using TGA. Reactive HPMCP showed higher $R_{p,max}$, smaller particle size, larger values of n and gel contents as compared with pristine HPMCP, due to the vinyl groups from HEMA, which can be reacted with styrene oligomers, in the reactive HPMCP.

• Advances in Traditional Medicine
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• v.8 no.3
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• pp.266-278
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• 2008

Erythrina stricta, a deciduous tree widely used traditionally in indigenous system of medicine for various ailments such as rheumatism, fever, leprosy, epilepsy etc. The leaves of Erythrina stricta was extracted with ethanol (70%) and used for the evaluation of various in vitro antioxidant assays which includes H - donor activity, nitric oxide scavenging, superoxide anion scavenging, reducing ability, hydroxyl radical, hydrogen peroxide scavenging, total phenolic content, total flavonoid content, total antioxidant activity by thiocyanate and phosphomolybdenum method, metal chelating, $\beta$-carotene bleaching, total peroxy radical assays. The pro-oxidant activity was measured using bleomycin-dependent DNA damage. Ex vivo models like lipid peroxidation and erythrocyte haemolysis were also used to study the antioxidant property of the extract. The various antioxidant activities were compared with suitable standard antioxidants such as ascorbic acid, butylated hydroxyl toluene, $\alpha$-tocopherol, curcumin, quercetin and Trolox. The generation of free radicals viz. $O_2^{{\cdot}-}$, $OH^{\cdot}$, $H_2O_2$, $NO^{\cdot}$ and peroxyl radicals were effectively scavenged by the ethanolic extract of Erythrina stricta. In all the methods, the extract offered strong antioxidant activity in a concentration dependent manner. The total phenolic content, flavonoid content and total antioxidant activity in Erythrina stricta were determined as microgram (g) pyrocatechol, quercetin and $\alpha$-tocopherol equivalent/mg respectively. The extract did not exhibit any prooxidant activity when compared with ascorbic acid. The results obtained in the present study clearly indicates that Erythrina stricta scavenges free radicals and reduces lipid peroxidation, ameliorating the damage imposed by oxidative stress in different disease conditions and serve as a potential source of natural antioxidant.

• Elastomers and Composites
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• v.40 no.1
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• pp.53-58
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• 2005

Carbon tetrachloride is very reactive chain transfer agent due to the resonance stability of the trichlorocarbon radicals after breaking of C-Cl bond. Effect of benzylic radical comparing to trichlorocarbon radicals in the chain tranrfer reactions was investigated. From the structural point of view, cumyl chloride is a good candidate because it has the C-Cl bond with benzylic radicals after displacement of C-Ci bond. The reactivity of free radical polymerization of styrene in the presence of cumyl chloride was compared with that of carbon tetrachloride by calculating chain transfer constants. Results show that the cumyl chloride acts as a stronger chain transfer agent than carbon tetrachloride. The calculated chain transfer constant of cumyl chloride shows higher value (0.0463) than that of carbon tetrachloride (0.0011) in the styrene polymerization. High reactivity of cumyl chloride comparing to that of carbon tetrachloride is probably due to the higher resonance stability or benzylic radical than that or trichlorocarbon radicals after breaking of C-Cl bond. Monte Carlo simulation method is applied for characterizing the validity of kinetic constants according to the ratio of chain transfer agent to monomer.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.214.2-215
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• 2003

Reactive oxygen species play an important role in aging. carcinogenesis, and certain neurological disorders of human beings in addition to the host-defensive mechanism of inflammatory response. Murine macrophages Raw264.7 released superoxide anions via NADPH oxidase complex and nitric oxide (NO) via iNOS synthase when the cells were stimulated with unopsonized zymosan binding to complement receptor. (omitted)

• Natural Product Sciences
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• v.9 no.4
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• pp.223-225
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• 2003

Ocimum sanctum, the Indian holy basil has significant abilities to scavenge highly reactive free radicals. Shade dried leaf powder of plant has extracted with water and alcohol, fractionated with different solvents. Both extracts and their fractions were found to be good scavengers of Superoxide and hydrogen peroxide. Free radical scavenging action of these compared with ascorbic acid, a known antioxidant.