Inhibiting ice recrystallization and optimization of cell viability after cryopreservation.

The ice recrystallization inhibition activity of various mono- and disaccharides has been correlated with their ability to cryopreserve human cell lines at various concentrations. Cell viabilities after cryopreservation were compared with control experiments where cells were cryopreserved with dimethylsulfoxide (DMSO). The most potent inhibitors of ice recrystallization were 220 mM solutions of disaccharides; however, the best cell viability was obtained when a 200 mM d-galactose solution was utilized. This solution was minimally cytotoxic at physiological temperature and effectively preserved cells during freeze-thaw. In fact, this carbohydrate was just as effective as a 5% DMSO solution. Further studies indicated that the cryoprotective benefit of d-galactose was a result of its internalization and its ability to mitigate osmotic stress, prevent intracellular ice formation and/or inhibit ice recrystallization. This study supports the hypothesis that the ability of a cryoprotectant to inhibit ice recrystallization is an important property to enhance cell viability post-freeze-thaw. This cryoprotective benefit is observed in three different human cell lines. Furthermore, we demonstrated that the ability of a potential cryoprotectant to inhibit ice recrystallation may be used as a predictor of its ability to preserve cells at subzero temperatures.

C-linked antifreeze glycoprotein (C-AFGP) analogues as novel cryoprotectants.

Significant cell damage occurs during cryopreservation resulting in a decreased number of viable and functional cells post-thawing. Recent studies have correlated the unsuccessful outcome of regenerative therapies with poor cell viability after cryopreservation. Cell damage from ice recrystallization during freeze-thawing is one cause of decreased viability after cryopreservation. We have assessed the ability of two C-AFGPs that are potent inhibitors of ice recrystallization to increase cell viability after cryopreservation. Our results indicate that a 1-1.5 mg/mL (0.5-0.8 mM) solution of C-AFGP 1 is an excellent alternative to a 2.5% DMSO solution for the cryopreservation of human embryonic liver cells.

Synthesis of C-linked triazole-containing AFGP analogues and their ability to inhibit ice recrystallization.

C-Linked antifreeze glycoprotein (C-AFGP) analogues have been shown to have potent ice recrystallization inhibition (IRI) activity. However, the lengthy synthesis of these compounds is not amenable to large-scale preparation for the many commercial, industrial, and medical applications that exist. This paper describes the synthesis of triazole-containing AFGPs using a convergent solid-phase synthesis (SPS) approach in which multiple carbohydrate derivatives are coupled to a resin-bound synthetic peptide in a single step. Modified "Click" conditions using dry DMF as solvent with catalytic Cu(II), sodium ascorbate, and microwave radiation afforded the synthesis of AFGP analogues 9-12 in 16-54% isolated yield. Compound 9 demonstrated no IRI activity, while compounds 10, 11, and 12 were moderate inhibitors of ice recrystallization. These results suggest that, while the triazole group is a structural mimetic of an amide bond, the amide bond in C-AFGP analogue 3 is an essential structural feature necessary for potent IRI activity.

Fluorescent dialdehyde ligand for the encapsulation of dinuclear luminescent lanthanide complexes.

Five dinuclear lanthanide complexes [Ln(III)(2)(hpd)(6)].solvent, Ln(III) = Eu(III) (1.2MeCN), Gd(III) (2.2MeCN), Tb(III) (3.MeCN.MeOH), Dy(III) (4.2MeCN), Ho(III) (5.2MeCN) and Hhpd (2-Hydroxyisophthaldehyde) were synthesised and structurally and magnetically characterised. X-Ray structural analysis shows all complexes are isostructural and crystallise in the triclinic P1 space group. The dinuclear complexes are composed of eight-coordinate lanthanide ions linked by two phenoxide bridges from two hpd(-) ligands. Complex 1 exhibits characteristic fluorescence in the visible region.

Triquinanes: a "one-pot" IMDA-tandem metathesis cascade strategy: ring-closing metathesis (RCM) dominates norbornene ROM!

A general route to linear triquinanes including a formal synthesis of (+/-)-Delta(9(12))-capnellene is described. This cascade strategy combines an intramolecular Diels-Alder reaction tandem metathesis protocol to generate the linear cis-anti-cis-tricyclo[6.3.0.0(2,6)]undecane skeleton directly. Significantly, the ring-closing-ring-opening-cross-metathesis (RCM-ROM-CM) sequence with our norbornene adducts is the only observed mechanism.