Antioxidant Potential of Aqueous Dispersions of Fullerenes C60, C70, and Gd@C82.

Ivan V Mikheev,Elena V Proskurnina,Mikhail A Proskurnin,Madina M Sozarukova,Dmitry Yu Izmailov,Ivan E Kareev

doi:10.3390/ijms22115838

Abstract

The antioxidant potential (capacity and activity) of aqueous fullerene dispersions (AFD) of non-functionalized C60, C70, and Gd@C82 endofullerene (in micromolar concentration range) was estimated based on chemiluminescence measurements of the model of luminol and generation of organic radicals by 2,2′-azobis(2-amidinopropane) dihydrochloride (ABAP). The antioxidant capacity was estimated by the TRAP method, from the concentration of half-suppression, and from the suppression area in the initial period. All three approaches agree and show that the antioxidant capacity of AFDs increased in the order Gd@C82 < C70 < C60. Mathematical modeling of the long-term kinetics data was used for antioxidant activity estimation. The effect of C60 and C70 is found to be quenching of the excited product of luminol with ABAP-generated radical and not an actual antioxidant effect; quenching constants differ insignificantly. Apart from quenching with a similar constant, the AFD of Gd@C82 exhibits actual antioxidant action. The antioxidant activity in Gd@C82 is 300-fold higher than quenching constants.

Highlights

Water-soluble fullerene species are promising for various medical applications, and they have been proposed as vital components for humans and environmental systems [1]
The trapping potential (TRAP) index is calculated from the latent period (Figure 1), while the total antioxidant reactivity (TAR) index is obtained from the rapid dinetchreeasstaetiionnlaurymlienveelsctyepniccealaffotrer“wadeadki”n(gorthreelaatnivteiolyxisdloawn)t.anTthioexaidnatniotsx. iSdtraincttlyacstpievaikty-nahrayslbeveeelnfodreatlelrtmhrieneed using tfhuellecroemneps u(it.e.r, tshime aunltaiotixoindaonfttwhaescchoenmsuimluemd,inFeigsuceren2ceb,dk,ifn).etics
We evaluated the properties of fullerenes as quenchers for the azobis(2-amidinopropane) dihydrochloride (ABAP)–luminol system (Figures S1 and S2, Supplementary Materials)

Summary

Introduction

Water-soluble fullerene species are promising for various medical applications, and they have been proposed as vital components for humans and environmental systems [1]. Fullerenes and, in particular, their water-soluble derivatives, are considered radical scavenging agents [2], possess antioxidant activity [3], acquire remarkable antimicrobial properties [4], cytotoxicity [5], DNA cleavage, and lipid peroxidation mediated by reactive oxygen species (ROS) [6]. Some antioxidants covalently bound to fullerenes increase antioxidant activity insignificantly. Grafting their cage with small-molecule antioxidant moieties such as synthetic phenols (2,6-di-tert-butyl-4-methylphenol) broadens their antioxidant potential conveying peroxyl radical-trapping activity up to 30 times [16]. A C60 derivative with covalently bonded analog of α-tocopherol with hydroxychromanyl moiety is an effective antioxidant acting in model lipid matrices: saturated stearic acid and unsaturated linolenic acid during the non-isothermal oxidation tested by differential scanning calorimetry [18]

Methods

Results

Discussion

Conclusion