X-Message-Number: 28265
Date: Thu, 27 Jul 2006 14:20:03 -0700 (PDT)
From: Doug Skrecky <>
Subject: why is cryotoxicity so low for diethylsulfoxide?

[After a landmark study in 2004, nothing further has been published on the
remarkable ability of diethylsulfoxide (DESO) to form vitrifiable
solutions with little short term toxicity. The very high cost of this
solvent, in comparison to dimethylsulfoxide (DMSO) might account for

Discussion of diethylsulfoxide.

Biopolymers. 2006 May;82(1):1-5.
Effect of diethylsulfoxide on the thermal denaturation of DNA.
  DNA thermal denaturation has been investigated in aqueous solutions of
diethylsulfoxide (DESO) by means of UV-vis and densimetry methods. It is
suggested that, on the one hand, the structural change of entire
solutions and, on the other hand, a direct interaction of DESO with DNA
are responsible for the observed peculiar behavior. The results obtained
were compared with those of dimethylsulfoxide (DMSO), also known from

Cryobiology. 2004 Aug;49(1):1-9.
Glass-forming property of the system diethyl sulphoxide/water and its
cryoprotective action on Escherichia coli survival.
  In this work the thermal properties of diethyl sulphoxide (Et2SO), as
well as its cryoprotective ability are studied and related to other
well-known cryoprotectant substances, like dimethyl sulphoxide
(Me2SO). We have investigated the thermal properties of Et2SO/water
systems using Differential Scanning Calorimetry at a very low
heating/cooling rate (2 degrees C/min). Liquid/solid or
glassy/crystalline transitions have been observed only for the solutions
with content of Et2SO ranging from 5 up to 40% w/w and/or greater than
85%. In the 45-75% w/w Et2SO range we have found a noticeable
glass-forming tendency and a great stability of the amorphous state to
the reheating. In samples with Et2SO content ranging from 80 to 85%, we
observed a great stability of the glass forming by cooling, but a lesser
stability to the subsequent reheating. The glass-forming tendency of
these solutions is discussed in terms of existing competitive interactions
between molecules of Et2SO, on the one hand, and Et2SO and water
molecules, on the other hand. The results are well explainable on the
basis of the model structure of water/Et2SO solutions, deduced by Raman
and infrared studies [J. Mol. Struct. 665 (2003) 285-292]. The
cryoprotective ability of Et2SO on Escherichia coli survival has been
also investigated, and a comparison among Et2SO and other widely used
cryoprotectants, like Me2SO and glycerol has been done. Survival of
E. coli, determined after freezing-thawing process, was maximal at 45% w/w
Et2SO (more than 85% viability). It should be noted that at the same
concentration the survival is only about 35% in the presence of Me2SO and
not more than 15% in the presence of glycerol. These features are well
consisted with the glass-forming properties of Et2SO.

Lett Appl Microbiol. 2002;34(6):417-21.
Effect of diethylsulphoxide on growth, survival and ion exchange of
Escherichia coli.
  AIMS: To study the effect of diethylsulphoxide (DESO) on Escherichia
coli growth, survival and ionic exchange in comparison with
dimethylsulphoxide (DMSO). METHODS AND RESULTS: Bacterial survival was
estimated by counting colony-forming units and by the most probable
number (five-tube) technique; the K+ and H+ transport and H(2) formation
were determined electrochemically. Diethylsulphoxide at concentrations
between 0.01 and 0.5% (w/v) stimulated and above 5% decreased the
anaerobic growth rate and survival. 2H+ : K+ exchange and H(2) formation
were lost at 5% DESO. At 0.05% DESO the kinetic characteristics of H+ : K+
exchange and H(2) formation were typical for Delta micro
(H(+)) -dependent TrkA uncoupled with F(0)F(1) under
respiration. CONCLUSIONS: Diethylsulphoxide at low concentrations serves
as an electron acceptor for an anaerobic respiratory chain stimulating
bacterial growth and survival through the modulation of H+ : K+ exchange
and H(2) formation activity. The effects of DESO were more pronounced
STUDY: Diethylsulphoxide determines essential biological and therapeutic
properties that make its application preferable.

Biofizika. 2002 Mar-Apr;47(2):315-7.
[Membrane potential before and after deep freezing of Escherichia coli in
the presence of dimethyl sulfoxide and diethyl sulfoxide]
  It was shown by the method of penetrating tetraphenylphosphonium
cations that low-temperature freezing (-196 degrees C) of Escherichia
coli leads to a sharp decrease (from 198 to 85 mV) in membrane
potential. Incubation of bacteria in a medium containing dimethyl
sulfoxide and diethyl sulfoxide as cryoprotectors results in a reduction
of the potential by 16 and 27 mV, respectively. It was also shown that
diethyl sulfoxide is more effective in maintaining the membrane potential
after freezing--thawing than dimethyl sulfoxide.

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=28265