n-Octyl (Thio)glycosides as Potential Cryoprotectants: Glass Transition Behaviour, Membrane Permeability, and Ice Recrystallization Inhibition Studies

Abstract

A series of eight n-octyl (thio)glycosides (1a, b-4a, b) with D-glucose or D-galactose-configured head groups and varying anomeric configuration were synthesized and evaluated for glass transition behaviour, membrane permeability, and ice recrystallization inhibition (IRI) activity. Of these, n-octyl b-D-glucopyranoside (2b) exhibited a high glass transition temperatures (T g ), both as a neat sample and 20 wt-% aqueous solution. Membrane permeability studies of this compound revealed cellular uptake to concentrations relevant to the inhibition of intracellular ice formation, thus presenting a promising lead candidate for further biophysical and cryopreservation studies. Compounds were also evaluated as ice recrystallization inhibitors; however, no detectable activity was observed for the newly tested compounds.

The need for novel cryoprotectants and cryopreservation protocols: Insights into the importance of biophysical investigation and cell permeability

“…In a recent study, n-octyl (thio)glycoside derivatives showed promising glass transition behaviour, and some could penetrate human monocytes (THP-1 cells [145]) without causing lysis. [97] These results provide useful insight for further modification and fine-tuning of analogue molecules to maximise permeability and glass transition behaviour.…”

“…While non-penetrating CPAs are important to cryopreservation and can greatly improve outcomes when used as an additive, penetrating CPAs offer the greatest potential for freezing new cell types, or even tissues and organs, because they inhibit intracellular ice formation. [19,49,97] Based on the above discussion, the ideal penetrating CPA will promote vitrification, inhibit ice recrystallization and reduce membrane/protein damage without being in itself too toxic. Therefore, many investigations into new CPAs begin with a few simple experiments to test: a) Does the solute penetrate the cell?…”

“…The thermal properties of solutions containing the potential CPA can be measured routinely using methods such as differential scanning calorimetry (DSC). [20,97,108,109] As these are widely known, they are not discussed further here.…”

“…Inhibition of ice recrystallization is measured by splat cooling assays where the mean size of ice crystals during thawing is measured. [12,33,97,110] An effective recrystallization inhibitor will result in observably smaller crystals.…”

RACI Awards 2017–19

“…The membrane permeability revealed cellular uptake relevant to the inhibition of intracellular ice formation, thereby presenting a promising lead for further biophysical and cryopreservation studies. [11] Angie Jarrad was awarded the Graham Johnston Best Thesis Award 2018 for her PhD dissertation at The University of Queensland. Currently an Alexander von Humboldt Fellow at the Helmholtz Centre for Infection Research in Germany, she contributes a Focus article on ATPfirefly bioluminescence-based detection of ATP.…”