Biological activity of carbonic nano-structures—comparison via enzymatic bioassay
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The aim of the work is to compare the biological activity of carbonic nano-structures of natural and artificial origination, namely, humic substances (HS) and fullerenols.
Materials and methods
The representative of the fullerenol group, С60Оy(OH)x where у + x = 20–22, was chosen. Enzyme-based luminescent bioassay was applied to evaluate toxicity and antioxidant properties of HS and fullerenol (F); chemiluminescent luminol method was used to study a content of reactive oxygen species (ROS) in the solutions. Toxicity of the bioactive compounds was evaluated using effective concentrations ЕС50; detoxification coefficients DOxT were applied to study and compare antioxidant activity of the compounds. Antioxidant activity and ranges of active concentrations of the bioactive compounds were determined in model solutions of organic and inorganic oxidizers—1,4-benzoquinone and potassium ferricianide.
Results and discussion
Values of ЕС50 revealed higher toxicity of HS than F (0.005 and 0.108 g L−1, respectively); detoxifying concentrations of F were found to be lower. Antioxidant ability of HS was demonstrated to be time-dependent; the 50-min preliminary incubation in oxidizer solutions was suggested as optimal for the detoxification procedure. On the contrary, F’ antioxidant effect demonstrated independency on time. Antioxidant effect of HS did not depend on amphiphilic characteristics of the media (values of DOxT were 1.3 in the solutions of organic and inorganic oxidizers), while this of F was found to depend: it was maximal (DOxT = 2.0) in solutions of organic oxidizer, 1,4-benzoquinone.
Both HS and F demonstrated toxicity and low-concentration antioxidant ability; however, quantitative characteristics of their effects were different. The differences were explained with HS polyfunctionality, higher ability to decrease ROS content, non-rigidity, and diffusion restrictions in their solutions. Antioxidant effect of the bioactive compounds was presumably attributed to catalytic redox activity of their π-fragments. The paper demonstrates a high potential of luminescent enzymatic bioassay to study biological activity of nano-structures of natural and artificial origination.
KeywordsAntioxidant activity Bioactive compounds Fullerenol Humic substances Toxicity Reactive oxygen species
Fullerenol С60Оy(OH)x, where у + x = 20–22
Nicotinamide adenine dinucleotide disodium salt reduced
Reactive oxygen species
This work was supported by the state budget allocated to the fundamental research at the Russian Academy of Sciences, project 0356-2017-0017; PRAN-32, Program: “Nanostructures: physics, chemistry, biology, technological basis.” Study of ROS involvement to antioxidant activity of humic substances was supported by the Russian Science Foundation, grant 16-14-10115.
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