Trans-palmitoleic acid, a dairy fat biomarker, stimulates insulin secretion and activates G protein-coupled receptors with a different mechanism from the cis isomer

Absorption, metabolism, and bioconversion of trans-palmitoleic acid in C57BL/6J mice: Implications for lipid metabolism

TRANS: palmitoleic acid (TPA), a naturally occurring trans fatty acid found in ruminant-derived products such as dairy products, has been associated with various potential health benefits. However, its digestion, absorption, tissue distribution, and metabolic properties following oral administration remain insufficiently understood. Here, we conducted pharmacokinetic analyses in C57BL/6J mice to evaluate the absorption, tissue distribution, and metabolism of TPA following oral administration. Our data showed that the plasma concentration of TPA peaked at 9.1 µg·mL-1 at 15 min postadministration, with a terminal elimination half-life of 201.1 min. Moreover, TPA was efficiently distributed to the heart, lung, liver, kidney, brain, and adipose tissue, reaching peak concentrations within 30 to 60 min. These results indicate that TPA is rapidly digested, absorbed, and distributed across multiple tissues in mice and exhibits slow metabolic clearance and an extended residence time in vivo. Within 0 to 480 min following oral administration, TPA underwent bioconversion to trans-vaccenic acid (TVA) and cis-9, trans-11 conjugated linoleic acid (9c11t-CLA), both of which are recognized for their extensive health benefits. The bioconversion rates were 71.57% to 72.44% for TVA and 44.05% to 53.23% for 9c11t-CLA. Furthermore, TPA significantly reduced triglyceride and total cholesterol levels in hepatocytes with steatosis. Notably, inhibiting the bioconversion of TPA to TVA and 9c11t-CLA did not impair its ability to reduce lipid accumulation in hepatocytes, suggesting that the beneficial effects of TPA on lipid metabolism are independent of its bioconversion to TVA and 9c11t-CLA. This study provides a reference for dairy fat intake and establishes a foundation for further exploration of the physiological effects of TPA.

Differentiation of Cis/trans-geometrical isomers in long-chain unsaturated fatty acids based on ion mobility and theoretical calculations

In recent years, fatty acids containing conjugated CCs have attracted extensive research attention due to their biological activities against human diseases. However, their differentiation is challenging. This study developed a comprehensive analytical solution to accurately differentiate cis/trans-fatty acid isomers using ion mobility mass spectrometry (IM-MS) and theoretical calculations. Cis/trans-fatty acids were mobility-differentiated via simple complexation with 1,5,9-triazacyclododecane (9C3N) or 1,4,8,11-tetraazacyclotetradecane (10C4N) and metal ions, obtaining baseline separation with a peak-to-peak resolution of 0.35-0.92. Moreover, the conformation of the complexes was optimized theoretically, revealing different binding modes between the cis/trans-fatty acid-9C3N/10C4N-metal ion systems, yielding in-depth structural data on the complexes and elucidating the principles of mobility separation. Furthermore, the proposed method was assessed in terms of quantification, accuracy, and precision repeatability. Finally, the method was applied to analyze oil samples. Given its simplicity, speed, and lack of chemical derivatization or chromatographic separation, this technique has potential applications in food analysis.

Lysophosphatidylcholines Enriched with cis and trans Palmitoleic Acid Regulate Insulin Secretion via GPR119 Receptor

Among lipids, lysophosphatidylcholines (LPCs) with various fatty acyl chains have been identified as potential agonists of G protein-coupled receptors (GPCRs). Recently, targeting GPCRs has been switched to diabetes and obesity. Concomitantly, our last findings indicate the insulin secretagogue properties of cis and trans palmitoleic acid (16:1, n-7) resulting from GPCR activation, however, associated with different signaling pathways. We here report the synthesis of LPCs bearing two geometrical isomers of palmitoleic acids and investigation of their impact on human pancreatic β cells viability, insulin secretion, and activation of four GPCRs previously demonstrated to be targeted by free fatty acids and LPCs. Moreover, molecular modeling was exploited to investigate the probable binding sites of tested ligands and calculate their affinity toward GPR40, GPR55, GPR119, and GPR120 receptors.