Yablonskaya O.I.1, Ryndina T.S.2, Voeikov V.L.1, Khokhlov A.N.2
Hydrated fullerene (HyFn) is the molecule of C60-fullerene (C60) encased in a stable shell of water molecules, providing hydrophilic properties to this complex and its solubility in aqueous solutions. HyFn, as well as chemically modified fullerenes and fullerenes solubilized in water in other ways, is known to have a broad spectrum of biological activities both in vivo and in vitro with no signs of toxicity. HyFn and various chemically modified fullerenes in aqueous environment exhibit a peculiar chemical activity - on the one hand, they can be regarded as strong antioxidants, on the other hand - as electron donors for oxygen, i.e. prooxidants. Given that C60 is not very active chemically and that in HyFn it is surrounded by a water shell, it could be assumed that the entire pattern of HyFn activity is due to unique properties of the water shell formed around C60. There are also some evidences of influence of HyFn at ultra-low concentrations on biochemical processes and free-radical reactions occurring in vitro. Previously, we have shown the effect of HyFn at ultra-low concentrations on redox processes in human whole blood as well as in aqueous bicarbonate solutions. In the present study we investigated effect of HyFn aqueous solution on the growth and "stationary phase aging" (accumulation of "age" changes in cultured cells during cell proliferation slowing down within a single passage and subsequent "aging" in the stationary phase of growth) of transformed B11-dii FAF28 Chinese hamster cells. The final calculated concentration of HyFn in the growth medium after serial dilutions of its original solution was equivalent to 10-19 M. It is paradoxical, but, in contrast to the known data about absence of HyFn cytotoxicity at higher concentrations, in our experiments it inhibited cell proliferation and accelerated the process of "stationary phase aging" of the cell culture. Moreover, addition of HyFn aqueous solution at this calculated concentration to the cells that had already reached the stationary phase of growth caused a rapid (within no more than 24 h) death of a significant part of the cell population. Perhaps, the observed features of HyFn at ultra-low concentration are determined by some special properties of the water surrounding C60, namely, its ability to serve as an electron donor and acceptor regulating redox processes in aqueous systems, especially those in which oxygen is involved. At the moment we cannot to rule out the possibility that HyFn at ultra-low concentrations affect transformed cells only. Therefore in our further studies we plan to carry out the similar experiments on normal fibroblasts possessing limited mitotic potential. Probably, the anti-aging effect of fullerenes revealed by other researchers in experimental animals is related to their antitumor and antibacterial activities.