The impact of selected xanthophylls on oil hydrolysis by pancreatic lipase: in silico and in vitro studies.

Lipase inhibition is one of the directions to control obesity. In vitro assays have confirmed the inhibitory effect of selected xanthophylls, including astaxanthin, fucoxanthinol, fucoxanthin, and neoxanthin. Similarly, an in-silico study also demonstrated the successful inhibition of pancreatic lipase by astaxanthin. Unfortunately, the efficacy of these protocols in the emulsion state typical of lipid digestion remains untested. To address this issue, the current study employed the pH-stat test, which mimics lipid digestion in the gastrointestinal tract, to evaluate native and prepared sea buckthorn and rapeseed oils with varying xanthophyll contents from 0 to 1400 mg/kg oil. Furthermore, a molecular docking of zeaxanthin and violaxanthin (commonly found in plant-based foods), astaxanthin (widely distributed in foods of marine origin) and orlistat (approved as a drug) was performed. The in-silico studies revealed comparable inhibitory potential of all tested xanthophylls (variation from - 8.0 to - 9.3 kcal/mol), surpassing that of orlistat (- 6.5 kcal/mol). Nonetheless, when tested in an emulsified state, the results of pH-stat digestion failed to establish the inhibitory effect of xanthophylls in the digested oils. In fact, lipolysis of native xanthophyll-rich sea buckthorn oil was approximately 22% higher than that of the xanthophyll-low preparation. The key insight derived from this study is that the amphiphilic properties of xanthophylls during the digestion of xanthophyll-rich lipids/meals facilitate emulsion formation, which leads to enhanced fat lipolysis.

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 ß 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.

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

Dietary trans-palmitoleic acid (trans 16:1n-7, tPOA), a biomarker for high-fat dairy product intake, has been associated with a lower risk of type 2 diabetes mellitus (T2DM) in some cross-sectional and prospective epidemiological studies. Here, we investigated the insulin secretion-promoting activity of tPOA and compared them with the effects evoked by the cis-POA isomer (cPOA), an endogenous lipokine biosynthesized in the liver and adipose tissue, and found in some natural food sources. The debate about the positive and negative relationships of those two POA isomers with metabolic risk factors and the underlying mechanisms is still going on. Therefore, we examined the potency of both POA isomers to potentiate insulin secretion in murine and human pancreatic ß cell lines. We also investigated whether POA isomers activate G protein-coupled receptors proposed as potential targets for T2DM treatment. We show that tPOA and cPOA augment glucose-stimulated insulin secretion (GSIS) to a similar extent; however, their insulin secretagogue activity is associated with different signaling pathways. We also performed ligand docking and molecular dynamics simulations to predict the preferred orientation of POA isomers and the strength of association between those two fatty acids and GPR40, GPR55, GPR119, and GPR120 receptors. Overall, this study provides insight into the bioactivity of tPOA and cPOA toward selected GPCR functions, indicating them as targets responsible for the insulin secretagogue action of POA isomers. It reveals that both tPOA and cPOA may promote insulin secretion and subsequently regulate glucose homeostasis.