The effect of naringin, a grapefruit flavonone was studied on bleomycin-induced genomic damage and alteration in the survival of cultured V79 cells. Exposure of V79 cells to bleomycin induced a concentration dependent elevation in the frequency of binucleate cells bearing micronuclei (MNBNC) and a maximum number of MNBNCs were observed in the cells treated with 50 microg ml(-1) bleomycin, the highest concentration evaluated. This genotoxic effect of bleomycin was reflected in the cell survival, where a concentration dependent decline was observed in the cells treated with different concentrations of bleomycin. Treatment of cells with 1 mm naringin before exposure to different concentrations of bleomycin arrested the bleomycin-induced decline in the cell survival accompanied by a significant reduction in the frequency of micronuclei when compared with bleomycin treatment alone. The cell survival and micronuclei induction were found to be inversely correlated. The repair kinetics of DNA damage induced by bleomycin was evaluated by exposing the cells to 10 microg ml(-1) bleomycin using single cell gel electrophoresis. Treatment of V79 cells with bleomycin resulted in a continuous increase in DNA damage up to 6 h post-bleomycin treatment as evident by migration of more DNA into the tails (% tail DNA) of the comets and a subsequent increase in olive tail moment (OTM), an index of DNA damage. Treatment of V79 cells with 1 mm naringin reduced bleomycin-induced DNA damage and accelerated DNA repair as indicated by a reduction in % tail DNA and OTM with increasing assessment time. A maximum reduction in the DNA damage was observed at 6 h post-bleomycin treatment, where it was 5 times lower than bleomycin alone. Our study, which was conducted on the basis of antioxidant, free radical scavenging and metal chelating properties of naringin demonstrates that naringin reduced the genotoxic effects of bleomycin and consequently increased the cell survival and therefore may act as a chemoprotective agent in clinical situations.
this paper reports a novel eutectoid nano-lamellar (fcc + L1 2 )/(Bcc + B2) microstructure that has been discovered in a relatively simple Al 0.3 cofeni high entropy alloy (HeA) or complex concentrated alloy (CCA). This novel eutectoid nano-lamellar microstructure presumably results from the complex interplay between Al-mediated lattice distortion (due to its larger atomic radius) in a face-centered cubic (FCC) CoFeNi solid solution, and a chemical ordering tendency leading to precipitation of ordered phases such as L1 2 and B2. This eutectoid microstructure is a result of solid-state decomposition of the FCC matrix and therefore distinct from the commonly reported eutectic microstructure in HEAs which results from solidification. This novel nano-lamellar microstructure exhibits a tensile yield strength of 1074 MPa with a reasonable ductility of 8%. The same alloy can be tuned to form a more damagetolerant fcc + B2 microstructure, retaining high tensile yield stress (~900 MPa) with appreciable tensile ductility (>20%), via annealing at 700 °C. Such tunability of microstructures with dramatically different mechanical properties can be effectively engineered in the same CCA, by exploiting the complex interplay between ordering tendencies and lattice distortion.High entropy alloys (HEAs), also referred to as complex concentrated alloys (CCAs) or multi-principal element alloys (MPEAs), offer the ability to design novel microstructures that have not been possible with conventional alloys. In recent times, there has been a rapid increase in papers reporting such novel microstructures with excellent mechanical properties 1-7 . However, there are still many unanswered questions related to the influence of composition and processing on the phase stability, transformation pathways, and microstructural evolution in these complex alloys. In an effort to understand solid solution strengthening in HEAs, the room temperature and high temperature tensile properties of solutionized ternary and quaternary subsets of CoCrFeNiMn (Cantor alloy), CoCrFeNi, CoFeNi, CoCrNi etc. were studied by Wu et al. 8 . They reported that yield strength may not be necessarily a simple function of number of elements but it is a complex relation. Among the systems investigated, CoCrNi had the highest yield strengths overall, at tested temperatures. Since then, numerous investigations have been carried out on this alloy to understand its mechanical behavior 9,10 . Their work also shows that FCC single phase solid solutions in HEAs perform better than conventional FCC single phase alloys and thus strengthening the single phase HEAs with precipitation is anticipated to produce alloys with excellent mechanical properties.Addition of Al to 3d transition element-based face-centered cubic (FCC) high entropy alloys (HEAs), typically containing the elements Co, Cr, Fe, and Ni, results in substantial changes in their microstructure and mechanical properties. This is due to the tendency of Al to effectively introduce an ordering tendency within the FCC matrix, f...
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