A Solvent-free Approach to Glycosyl Amides: Towards the Synthesis of α-N-Galactosyl Ceramides.

A new, simple and efficient method for the synthesis of both α- and ß-glycosyl amides using solvent-free conditions is described. This method involves the coupling of glycosyl amines with the p-nitrophenol esters of lipids as a key step.

A Humanized Mouse Model Coupled with Computational Analysis Identifies Potent Glycolipid Agonist of Invariant NKT Cells.

Invariant natural killer T (iNKT) cells play an important role in many innate and adaptive immune responses, with potential applications in cancer immunotherapy. The glycolipid KRN7000, an α-galactosylceramide, potently activates iNKT cells but has shown limited anticancer effects in human clinical trials conducted so far. In spite of almost three decades of structure-activity relationship studies, no alternative glycolipid has yet emerged as a superior clinical candidate. One reason for the slow progress in this area is that standard mouse models do not accurately reflect the specific ligand recognition by human iNKT cells and their requirements for activation. Here we evaluated a series of KRN7000 analogues using a recently developed humanized mouse model that expresses a human αTCR chain sequence and human CD1d. In this process, a more stimulatory, previously reported but largely overlooked glycolipid was identified, and its activity was probed and rationalized via molecular simulations.

Truncated Itraconazole Analogues Exhibiting Potent Anti-Hedgehog Activity and Improved Drug-like Properties.

We conducted a structure-activity relationship study to explore simplified analogues of the itraconazole (ITZ) scaffold for their ability to inhibit the hedgehog (Hh) signaling pathway. These analogues were based on exploring the effects of chemical modifications to the linker and triazolone/side chain region of ITZ. Analogue 11 was identified as the most potent compound in our first generation, with an IC50 value of 81 nM in a murine Hh-dependent basal cell carcinoma. Metabolic identification studies led us to identify truncated piperazine (26) as the major metabolite in human liver microsomes (HLMs) and an improved Hh pathway inhibitor (IC50 = 22 nM). This work verifies that continued truncation of the ITZ scaffold is a practical method to maintain potent anti-Hh activity while also reducing the molecular weight for the ITZ scaffold and achieving improved pharmacokinetic properties.

Dual Modifications of α-Galactosylceramide Synergize to Promote Activation of Human Invariant Natural Killer T Cells and Stimulate Anti-tumor Immunity.

Glycosylceramides that activate CD1d-restricted invariant natural killer T (iNKT) cells have potential therapeutic applications for augmenting immune responses against cancer and infections. Previous studies using mouse models identified sphinganine variants of α-galactosylceramide as promising iNKT cell activators that stimulate cytokine responses with a strongly proinflammatory bias. However, the activities of sphinganine variants in mice have generally not translated well to studies of human iNKT cell responses. Here, we show that strongly proinflammatory and anti-tumor iNKT cell responses were achieved in mice by a variant of α-galactosylceramide that combines a sphinganine base with a hydrocinnamoyl ester on C6″ of the sugar. Importantly, the activities observed with this variant were largely preserved for human iNKT cell responses. Structural and in silico modeling studies provided a mechanistic basis for these findings and suggested basic principles for capturing useful properties of sphinganine analogs of synthetic iNKT cell activators in the design of immunotherapeutic agents.

Development of new P-chiral P,π-dihydrobenzooxaphosphole hybrid ligands for asymmetric catalysis.

A new family of P-chiral P,π-hybrid ligands was prepared from the dihydrobenzooxaphosphole core. These new ligands were demonstrated to be both sterically and electronically tunable at the substituents on the phosphorus atom and the π-system of the ligand. Application of these new ligands to the catalytic asymmetric addition of boronic acids to imine electrophiles was shown to proceed with high levels of enantioinduction.