René Dolmazon

Conformational analysis of isolated docosahexaenoic acid (22:6 n-3) and its 14 (S) and 11 (S) hydroxy derivatives by force field calculations

Abstract Docosahexaenoic acid (DHA) and two of its lipoxygenase end-products, the 11- and 14-hydroxy derivatives, of biological relevance were studied for their privileged conformations using molecular mechanics. As an isolated molecule, DHA adopted helical conformations. However, a more extended helical conformation would fit better with the hydrophobic interactions expected with DHA esterified within glycerophospholipids. The most stable conformations of the hydroxy derivatives of DHA appeared as coiled ones where an intramolecular hydrogen bond occurs between the carboxylic and the hydroxy groups. Among the latter conformations, one for each hydroxy derivative would fit better with the requirement of the largest distance between the hydrophobic and hydrophilic centers within the molecule for being inserted in membrane phospholipids where the hydroxy derivatives are likely to be located in their unesterified form. As thromboxane A2 (TXA2) antagonist, DHA and its hydroxy derivatives were compared with minimized conformations of TXA2 and one of its potent antagonist recently described, (R)-(+)-TCV-144. Interestingly, the 14-hydroxy derivative of DHA, previously reported as the most potent TXA2 antagonist among the DHA derivatives, exhibited stable conformations quite similar to those of TXA2 and (R)-(+)-TCV-144.

Diterpenoids from Kyllinga erecta

Abstract 16-Hydroxy-manoyloxide, a new derivative of manoyloxide, ambreinolide and norambreinolide have been isolated from the ethyl acetate extract of Kyllinga erecta rhizomes.

Two step synthesis of 1,3-acetylated, -butyroylated and -caproylated triglycerides from a microorganism oil rich in Docosahexaenoic Acid (DHA)

Abstract 1,3-acetylated, -butyroylated and -caproylated triglycerides were prepared in two steps by hemisynthesis from microorganism triglycerides rich in DHA. The triglycerides were first enzymatically transesterified into 2-monoacyl-glycerols which were then acylated with saturated short acid derivatives without significant migration of the β-long chain fatty acyl groups to the α position.

An epi-13-manoyloxide diterpenoid from Kyllinga erecta

16-Hydroxy-13-epi-manoyloxide, a new derivative of 13-epi-manoyloxide, has been isolated from the ethyl acetate extract of Kyllinga erecta rhizomes.

A new diterpenoid from Kyllinga erecta S

The structure of a diterpenoid isolated from the methylene chloride extract of Kyllinga erecta rhizomes has been elucidated as 11α-hydroxy-13-epi-manoyloxide by spectral analysis (1H, 13C and MS). Deoxygenation of this compound gave the well known 13-epi-manoyloxide. Copyright