Claire Sauvée

Highly Efficient, Water‐Soluble Polarizing Agents for Dynamic Nuclear Polarization at High Frequency

Well polarized: Two new polarizing agents PyPol and AMUPol soluble in glycerol/water mixtures are used for dynamic nuclear polarization (DNP) NMR spectroscopy. The enhancement factors (e) are about 3.5 to 4 times larger than for the established agent TOTAPOL at 263 and 395 GHz. For AMUPol, the temperature dependence of e allows DNP experiments to be performed at temperatures significantly higher than for typical high-field DNP NMR experiments.

Solid-Phase Polarization Matrixes for Dynamic Nuclear Polarization from Homogeneously Distributed Radicals in Mesostructured Hybrid Silica Materials

Mesoporous hybrid silica-organic materials containing homogeneously distributed stable mono- or dinitroxide radicals covalently bound to the silica surface were developed as polarization matrixes for solid-state dynamic nuclear polarization (DNP) NMR experiments. For TEMPO-containing materials impregnated with water or 1,1,2,2-tetrachloroethane, enhancement factors of up to 36 were obtained at ∼100 K and 9.4 T without the need for a glass-forming additive. We show that the homogeneous radical distribution and the subtle balance between the concentration of radical in the material and the fraction of radicals at a sufficient inter-radical distance to promote the cross-effect are the main determinants for the DNP enhancements we obtain. The material, as well as an analogue containing the poorly soluble biradical bTUrea, is used as a polarizing matrix for DNP NMR experiments of solutions containing alanine and pyruvic acid. The analyte is separated from the polarization matrix by simple filtration.

Biomolecular DNP‐Supported NMR Spectroscopy using Site‐Directed Spin Labeling

Dynamic nuclear polarization (DNP) has been shown to greatly enhance spectroscopic sensitivity, creating novel opportunities for NMR studies on complex and large molecular assemblies in life and material sciences. In such applications, however, site-specificity and spectroscopic resolution become critical factors that are usually difficult to control by current DNP-based approaches. We have examined in detail the effect of directly attaching mono- or biradicals to induce local paramagnetic relaxation effects and, at the same time, to produce sizable DNP enhancements. Using a membrane-embedded ion channel as an example, we varied the degree of paramagnetic labeling and the location of the DNP probes. Our results show that the creation of local spin clusters can generate sizable DNP enhancements while preserving the intrinsic benefits of paramagnetic relaxation enhancement (PRE)-based NMR approaches. DNP using chemical labeling may hence provide an attractive route to introduce molecular specificity into DNP studies in life science applications and beyond.

The A-CD analogue of 16 beta,17 alpha-estriol is a potent and highly selective estrogen receptor beta agonist

Selective estrogen receptor beta (ER beta) agonists display neuroprotective properties in animal models and hold promise in the treatment of neurodegenerative diseases. In our quest to design, synthesize and evaluate potent and safe ER beta agonists, we focused on making an analogue of 16 beta,17 alpha-estriol (16,17-epiestriol), a potent and one of the most ER beta selective endogenous estrogens reported. Herein we disclose the synthesis and in vitro evaluation of an analogue based on the recently introduced A-CD scaffold. A 14-step synthesis based on the Hajos-Parrish ketone resulted in the discovery of (1S,2S,3aS,5S,7aS)-5-(4-hydroxyphenyl)-7a-methyloctahydro-1H-indene-1,2-diol (15). This A-CD analogue of 16 beta, 17 alpha-estriol is a highly selective (500-fold) ER beta full agonist over ER alpha with a pEC(50) of 7.7 at ER beta. Molecular modelling suggests that 15 turns around in the ligand-binding domain compared to estriol, thus the 7a-methyl occupies the alpha-face, which might explain the high selectivity. (Less)