A synthon for C-20 trideuterated eicosanoids: Preparation of [2H3]-arachidonic acid

Amidative Cyclization of Alkynyl Esters to Access Pyrazin-1(2H)-ones: Application to the Synthesis of Peramine and Dibromophakellin

Herein, we report an efficient 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed tandem intermolecular amidation and regioselective intramolecular 6-exo-dig cyclization of alkynyl esters to efficiently access pyrazine-1(2H)-one scaffolds. This organo-catalyzed [5 + 1] annulation features a broad substrate scope concerning both annulating partners. Total syntheses of peramine and formal syntheses of dibromophakellin natural products were achieved to show the application potential of the method.

Arachidonic acid: Physiological roles and potential health benefits - A review

It is time to shift the arachidonic acid (ARA) paradigm from a harm-generating molecule to its status of polyunsaturated fatty acid essential for normal health. ARA is an integral constituent of biological cell membrane, conferring it with fluidity and flexibility, so necessary for the function of all cells, especially in nervous system, skeletal muscle, and immune system. Arachidonic acid is obtained from food or by desaturation and chain elongation of the plant-rich essential fatty acid, linoleic acid. Free ARA modulates the function of ion channels, several receptors and enzymes, via activation as well as inhibition. That explains its fundamental role in the proper function of the brain and muscles and its protective potential against Schistosoma mansoni and S. haematobium infection and tumor initiation, development, and metastasis. Arachidonic acid in cell membranes undergoes reacylation/deacylation cycles, which keep the concentration of free ARA in cells at a very low level and limit ARA availability to oxidation. Metabolites derived from ARA oxidation do not initiate but contribute to inflammation and most importantly lead to the generation of mediators responsible for resolving inflammation and wound healing. Endocannabinoids are oxidation-independent ARA derivatives, critically important for brain reward signaling, motivational processes, emotion, stress responses, pain, and energy balance. Free ARA and metabolites promote and modulate type 2 immune responses, which are critically important in resistance to parasites and allergens insult, directly via action on eosinophils, basophils, and mast cells and indirectly by binding to specific receptors on innate lymphoid cells. In conclusion, the present review advocates the innumerable ARA roles and considerable importance for normal health.

Direct resolution of epoxyeicosatrienoic acid enantiomers by chiral-phase high-performance liquid chromatography

A chromatographic method was developed to separate enantiomers of four regioisomeric epoxyeicosatrienoic acids (EETs), which are cytochrome P-450 monooxygenase products of arachidonic acid. Enantiomers of individual epoxyeicosatrienoic acids were separated by chiral-phase HPLC using Chiralcel OD columns. In contrast to the pre-derivatization of EETs, the method is simple and convenient. It can be readily used in analytical studies and in preparative applications. The method can also be applied to the separation of methyl ester derivatives of epoxyeicosatrienoic acid enantiomers.

Preparation of omega trideuterated sulfidopeptide leukotrienes: analysis by FAB/MS

C-20 Trideuterated leukotriene A4 methyl ester was prepared by Wittig condensation of a deuterated C9-phosphonium salt with a C11-epoxydienal. It was then treated separately with glutathione, cysteinylglycine and cysteine. The resulting esters were saponified to give C-20 trideuterated leukotrienes C4, D4 and E4 respectively. Fast atom bombardment mass spectrometry showed that the synthetic compounds contained from 0.5 to 1.0% protium impurity. Introduction of deuterium at C-20 ensures that it is stable to a wide variety of reagents and reaction conditions. The deuterated leukotrienes will serve as internal standards for the quantitative analysis by mass spectrometry of endogenous sulfidopeptide leukotrienes present in biological fluids.