Total Synthesis of Cardiolipins Containing Chiral Cyclopropane Fatty Acids.

Cardiolipin (CL) is a phospholipid located in both the eukaryotic mitochondrial inner membrane and the bacterial cell membrane. Some bacterial CLs are known to contain cyclopropane moieties in their acyl chains. Although the CLs are thought to be involved in the innate immune response, there have been few attempts at chemical synthesis of the CLs, and detailed studies of their biological activities are scarce. Thus, we have developed a synthetic route to CLs containing chiral cyclopropane moieties.

Simple Gd3+-Neu5NAc complexation results in NMR chemical shift asymmetries of structurally equivalent complex-type N-glycan branches.

In the present Communication, we propose a quite simple but previously overlooked approach for conveniently analyzing, assigning, and extracting sialic acid-containing N-glycan structures using high-resolution NMR spectroscopy without pre-installing metal chelators. Paramagnetic metals, such as Gd3+, appear to bind to the carboxyl groups of N-acetylneuraminic acid when introduced at room temperature, leading to the measurement of nonequivalent proton and carbon NMR spectral signals among otherwise "identical" glycan branched structures.

A Reduction-Based Sensor for Acrolein Conjugates with the Inexpensive Nitrobenzene as an Alternative to Monoclonal Antibody.

Acrolein, a highly toxic α, ß-unsaturated aldehyde, has been a longstanding key biomarker associated with a range of disorders related to oxidative stresses. One of the most promising methods for detecting acrolein involves the use of antibodies that can recognize the acrolein-lysine conjugate, 3-formyl-3, 4-dehydropiperidines (FDP), within oxidatively stressed cells and tissues from various disease states. We have uncovered here that FDP could reduce nitroarenes in high yields at 100 °C in the presence of excess CaCl2 as a Lewis acid promoter. This unique transformation allowed for the development of a de novo method for detecting levels of FDPs generated from proteins in urine or blood serum samples. Thus we successfully converted a non-fluorescent and inexpensive 4-nitrophthalonitrile probe to the corresponding fluorescent aniline, thereby constituting the concept of fluorescent switching. Its sensitivity level (0.84 nmol/mL) is more than that of ELISA assays (3.13 nmol/mL) and is already equally reliable and reproducible at this early stage of development. More importantly, this method is cost effective and simple to operate, requiring only mixing of samples with a kit solution. Our method thus possesses potential as a future alternative to the more costly and operatively encumbered conventional antibody-based methods.

Imino [4+4] cycloaddition products as exclusive and biologically relevant acrolein-amine conjugates are intermediates of 3-formyl-3,4-dehydropiperidine (FDP), an acrolein biomarker.

We demonstrated synthetically that the eight-membered heterocycles 2,6,9-triazabicyclo[3.3.1]nonanes and 1,5-diazacyclooctanes are the initial and exclusive products of the reaction, through an imino [4+4] cycloaddition, of biologically relevant amines with acrolein. The stabilities of the aminoacetals within the eight-membered heterocycles determined whether the product was subsequently transformed gradually into the 3-formyl-3,4-dehydropiperidine (FDP), which is widely used as an oxidative stress marker. The reactivity profiles discovered in this study suggested that some of the imino [4+4] cycloaddition products are reactive intermediates of FDP and contribute to the mechanisms underlying the oxidative stress response to acrolein.