Radical-induced DNA Strand Scission Research Articles

Bioactive peptides from shrimp shell processing discards: Antioxidant and biological activities

Protein hydrolysates were prepared from shrimp discards, using various enzymes, which were subsequently analyzed for their antioxidant potential and biological activities. Raw shrimp shell discards hydrolysates (RSH) and isolated shrimp shell protein hydrolysates (SPH) exhibited radical scavenging activities (ABTS, DPPH and hydroxyl), reducing power and ferrous ion chelating ability. In addition, RSH and SPH inhibited beta-carotene bleaching in an oil-in-water emulsion, cupric ion induced LDL cholesterol peroxidation as well as peroxyl and hydroxyl radical induced DNA strand scission effectively. In-vitro determination of ACE inhibitory activity by RSH and SPH showed that these hydrolysates could be used in supplements, foods or in the purified form as potential pharmaceuticals for blood pressure control. Moreover, shrimp shell discard protein hydrolysate fractions with highest ACE inhibitory activity were further subjected to gel filtration, mass spectrometry and peptide sequencing. Three potential ACE inhibitory bioactive peptides were identified form shrimp shell discard for the first time.

Simultaneous quantification of ten constituents of Xanthoceras sorbifolia Bunge using UHPLC-MS methods and evaluation of their radical scavenging, DNA scission protective, and α-glucosidase inhibitory activities

The present study was designed to investigate the bioactive constituents of Xanthoceras sorbifolia in terms of amounts and their antioxidant, DNA scission protection, and α-glucosidase inhibitory activities. Simultaneous quantification of 10 X. sorbifolia constituents was carried out by a newly established ultra-high performance liquid chromatography-quadrupole mass spectrometry method (UHPLC-MS). The antioxidant activities were evaluated by measuring DPPH radical scavenging and DNA scission protective activities. The α-glucosidase inhibitory activities were investigated by using an assay with α-glucosidase from Bacillus Stearothermophilus and disaccharidases from mouse intestine. We found that the wood of X. sorbifolia was rich in phenolic compounds with the contents of catechin, epicatechin, myricetin, and dihydromyricetin being 0.12–0.19, 1.94–2.16, 0.77–0.91, and 6.76–7.89 mg·g−1, respectively. The four constituents strongly scavenged DPPH radicals (with EC50 being 4.2, 3.8 and 5.7 μg·mL−1, respectively) and remarkably protected peroxyl radical-induced DNA strand scission (92.10%, 94.66%, 75.44% and 89.95% of protection, respectively, at a concentration of 10 μmol·L−1). A dimeric flavan 3-ol, epigallocatechin-(4β→8, 2β→O-7)-epicatechin potently inhibited α-glucosidase with an IC50 value being as low as 1.2 μg·mL−1. The established UHPLC-MS method could serve as a quality control tool for X. sorbifolia. In conclusion, the high contents of antioxidant and α-glucosidase inhibitory constituents in X. sorbifolia support its use as complementation of other therapeutic agents for metabolic disorders, such as diabetes and hypertension.

Antioxidant Activity and Protective Effect Against Plasmid DNA Strand Scission of Leaf, Bark, and Heartwood Extracts from Acacia catechu

The antioxidant activity of methanol extract/fractions of leaf, bark, and heartwood of Acacia catechu was evaluated by various antioxidant assays, including free radical, superoxide and hydroxyl radical, reducing power, metal ion chelation, as well as hydroxyl radical induced DNA strand scission. The leaf, bark, and heartwood powder was extracted in methanol and the lyophilized methanol extract was fractionated with different solvents in the order of increasing polarity. The results indicate that ethyl acetate fraction of heartwood has the highest antioxidant capacities, presenting lower EC(50) values particularly in free radical scavenging activity, including DPPH radicals (4.76 ± 0.14 μg/mL), superoxide anions (26.21 ± 0.79 μg/mL), and hydroxyl radicals (33.69 ± 1.42 μg/mL), in direct assay systems. Reducing power was also highest in ethyl acetate fraction of heartwood (EC(50) of 79.05 ± 1.02 μg/mL). As for the chelating power on ferrous ions, leaf extract was more effective than bark and heartwood extracts. Furthermore, the ethyl acetate and acetone fractions of heartwood significantly protected pBR322 supercoiled plasmid DNA against strand scission induced by hydroxyl radicals in a Fenton's reaction mixture. The present investigation suggests that the three organs of A. catechu differ significantly in their antioxidant potential as seen in the DPPH radical scavenging assay, reducing power assay, metal ion chelating assay, superoxide radical scavenging assay and hydroxyl radical scavenging assay. Further, our results showed that crude methanol extract and ethyl acetate fraction of heartwood of A. catechu might have a good potential as a source for natural health products due to its antioxidant and DNA protective activities.

Free radical scavenging activity and antiproliferative potential of Polygonum cuspidatum root extracts

Polygonum cuspidatum is widely used as a medicinal herb in Asia. In this study, ethanol and ethyl acetate extracts of P. cuspidatum root were assayed for their 1,1-diphenyl-2-hydrazyl (DPPH) and hydroxyl free radical scavenging activities, total phenolics content, protective effect against DNA damage, and antiproliferative activity on human lung cancer cells. The ethanol and ethyl acetate (lipophilic phase) extracts of P. cuspidatum had significant scavenging effects on DPPH and hydroxyl radicals. Total phenolics content of ethanol and ethyl acetate (lipophilic phase) extracts of P. cuspidatum were 276.78 +/- 39.31 and 231.73 +/- 5.04 mg/ml, respectively; both extracts protected against hydroxyl radical-induced DNA strand scission. Furthermore, the extracts of P. cuspidatum induced apoptosis and inhibited cell growth in A549 and H1650 cell lines, suggesting that P. cuspidatum root extracts exhibit an antiproliferative effect on human lung cancer cells.

Synthesis and Characterization of Substituted Ethyl 2-(1-aminocyclobutyl)- 5-(benzoyloxy)-6-hydroxypyrimidine-4-carboxylate Derivatives as Antioxidant Agents

A series of novel ethyl 2-(1-aminocyclobutyl)-5-(benzoyloxy)-6-hydroxy-pyrimidine-4-carboxylate derivatives 8(a-i) were synthesized by nucleophilic substitution reaction of ethyl 2-(1-aminocyclobutyl)-5-(benzoyloxy)-6-hydroxypyrimidine- 4-carboxylate (7) with different substituted aliphatic/aromatic sulfonyl chlorides (R-SO2-Cl). All the synthesized compounds were characterized by IR, 1H NMR and LC/MS analysis. The synthesized compounds were evaluated for their antioxidant activity by diphenylpicrylhydrazyl (DPPH) assay and also by hydroxy radical induced DNA strand scission assay. Among the synthesized compounds 8c, 8f and 8i showed promising antioxidant activity. Keywords: Benzyl 1-cyanocyclobutylcarbamate, Pyrimidine, Hydroxy radical, DPPH Assay, Antioxidant

Antioxidant activity of Pyrrosia petiolosa

The ethanol extract of Pyrrosia petiolosa showed an antioxidant activity as determined by free radical scavenging, superoxide radical scavenging, lipid peroxidation, and hydroxyl radical-induced DNA strand scission assays.

Antioxidant activity of extract from Polygonum cuspidatum

Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oí Polygonum cuspidatum extract is 110 microg/ml in free radical scavenging assays, 3.2 microg/ml in superoxide radical scavenging assays, and 8 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 +/- 42.6 mg/g and 62.3 +/- 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects.

Antioxidant activity of extract from Polygonum aviculare L.

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation, and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum aviculare L. (Polygonaceae) has antioxidant activity is unknown. In this study, dried Polygonum aviculare L. was extracted by ethanol, and the extract was lyophilized. The antioxidant activities of extract powder were examined by free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays. The results show that the IC50 value of Polygonum aviculare L. extract is 50 microg/ml in free radical scavenging assays, 0.8 microg/ml in superoxide radical scavenging assays, and 15 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum aviculare L. extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 677.4 +/- 62.7 microg/g and 112.7 +/- 13 microg/g. The results indicate that Polygonum aviculare L. extract clearly has antioxidant effects.

Antioxidant activity and protective effect on DNA strand scission of Rooibos tea (Aspalathus linearis)

Rooibos tea (Aspalathus linearis) was extracted by refluxing with water and 75% ethanol as a solvent. Antioxidant activity and protective effect on DNA strand scission were investigated by using different antioxidant assay systems and DNA strand nicking assay, respectively. 75% Ethanol extract has higher content of total soluble phenolics and flavonoid than water extract. Antioxidant activities such as hydrogen donating capacity and scavenging activity of hydrogen peroxide were higher in 75% ethanol extract than in water extract except the rate constant with hydroxyl radical. Peroxyl radical induced DNA strand scission was prevented by both 75% ethanol and water extract and hydroxyl radical induced DNA strand scission was not. This result indicates that total soluble phenolics, specially flavonoid, of Rooibos tea are responsible for several kinds of antioxidant activities and preventive activity on peroxyl radical induced DNA strand scission.

Antioxidant activity of extracts from Acacia confusa bark and heartwood.

The antioxidant activity of extracts from bark and heartwood of Acacia confusa was evaluated by various antioxidant assays, including free radical and superoxide radical scavenging assays and lipid peroxidation assay as well as hydroxyl radical-induced DNA strand scission assay. In addition, an ex vivo antioxidant assay using a flow cytometric technique was also employed in this study. The results indicate that both bark and heartwood extracts clearly have strong antioxidant effects. Similar inhibitory activities for each test sample were found for both 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical generation and lipid peroxidation. As for the superoxide radical scavenging activity, the heartwood extract was more effective than the bark extract. Furthermore, the heartwood extract protected PhiX174 supercoiled DNA against strand scission induced by ultraviolet photolysis of H2O2, and it reduced the amounts of intracellular hydrogen peroxide, a reactive oxygen species, when it was co-incubated with human promyelocytic leukemia (HL-60) cells under oxidative stress.

Augmentation of bleomycin-induced DNA damage in intact cells

Bleomycin, an important cause of pulmonary fibrosis, is known to produce DNA damage. The mechanism for this damage in vitro is related to free radical production by a bleomycin and iron complex. To determine whether bleomycin causes damage to DNA in vivo by a similar mechanism, we used a viral minichromosome that is replicated in cultured cells. Bleomycin causes dose-dependent damage to intracellular DNA, and this damage is augmented by Fe2+ but not Fe3+. The augmentation of the bleomycin-induced DNA damage caused by Fe2+ is also dose dependent in that increasing DNA damage occurs with increasing amounts of Fe2+. These studies demonstrate that bleomycin causes damage to DNA in vivo and suggest that bleomycin must rely on Fe2+ to donate an electron for oxygen radical-induced DNA strand scission.