Ectoine, a compatible solute and osmolyte, is known to be an effective
protectant of biomolecules and whole cells against heating, freezing and
extreme salinity. Protection of cells (human keratinocytes) by ectoine against
ultraviolet radiation has also been reported by various authors, although the
underlying mechanism is not yet understood. We present the first electron
irradiation of DNA in a fully aqueous environment in the presence of ectoine
and at high salt concentrations. The results demonstrate effective protection
of DNA by ectoine against the induction of single-strand breaks by ionizing
radiation. The effect is explained by an increase in low-energy electron
scattering at the enhanced free- vibrational density of states of water due to
ectoine, as well as the use of ectoine as an hydroxyl-radical scavenger. This
was demonstrated by Raman spectroscopy and electron paramagnetic resonance
(EPR)
