BACKGROUND: Glycerolysis, with its advantages of readily available raw materials, simple operation, and mild reaction conditions, is a primary method for producing diacylglycerol (DAG). However, enzymatic glycerolysis faces challenges such as high enzyme costs, low reuse efficiency, and poor stability. The study aims to develop a cost-effective immobilized enzyme by covalently binding lipase to pre-activated carriers through the selection of suitable lipases, carriers, and activating agents. The optimization is intended to improve the glycerolysis reaction for efficient DAG production.
RESULTS: Lipase CN-TL (from Thermomyces lanuginosus) was selected through glycerolysis reaction and molecular docking to catalyze the glycerolysis reaction. Optimizing the immobilization method by covalently binding CN-TL to poly(ethylene glycol) diglycidyl ether (PEGDGE)-preactivated resin LX-201A resulted in the preparation of the immobilized enzyme TL-PEGDGE-LX. The immobilized enzyme retained over 90% of its initial activity after five consecutive reactions, demonstrating excellent reusability. The DAG content in the product remained at 84.8% of its initial level, further highlighting the enzyme\'s potential for reusability and its promising applications in the food and oil industries.
CONCLUSIONS: The immobilized lipase TL-PEGDGE-LX, created by covalently immobilizing lipase CN-TL on PEGDGE-preactivated carriers, demonstrated broad applicability and excellent reusability. This approach offers an economical and convenient immobilization strategy for the enzymatic glycerolysis production of DAG. © 2024 Society of Chemical Industry.

Diacylglycerol (DAG) is generally considered one of the precursors of 3-chloropropanol esters (3-MCPDE) and glycidyl esters (GEs). This study aimed to evaluate static heating and stir-frying properties of peanut oil (PO) and PO based 58% and 82% DAG oils (PDAG-58 and PDAG-82). Observations revealed that, phytonutrient levels notably diminished during static heating, with PDAG exhibiting reduced oxidative stability, but maintaining a stability profile similar to PO over a short period. During stir-frying, 3-MCPDE content initially increased and then decreased whereas the opposite was observed for GEs. Furthermore, as temperature, and NaCl concentration increased, there was a corresponding increase in the levels of 3-MCPDE and GEs, although remained within safe limits. When used in suitable concentrations, these findings underscore the potential of DAG, as a nutritionally rich and oxidatively stable alternative to conventional cooking oils, promoting the use of DAG edible oil in heat-cooked food systems.

Pickering foams have great potential for applications in aerated foods, but their foaming ability and physical stability are still far from satisfactory. Herein, solid lipid particles (SLNs) were fabricated by using diacylglycerol of varying acyl chain lengths with modification by a protein. The SLNs showed different crystal polymorphisms and air-water interfacial activity. C14-DAG SLN with a contact angle ∼ 79° formed aqueous foam with supreme stability and high plasticity. Whey protein isolate and sodium caseinate (0.1 wt %) considerably enhanced the foamability and interfacial activity of SLNs and promoted the packing of particles at the bubble surface. However, high protein concentration caused foam destruction due to the competitive adsorption effect. β-sheet increased in protein after adsorption and changed the polymorphism and thermodynamic properties of SLN. The foam collapsing behaviors varied in the presence of protein. The results gave insights into fabricating ultrastable aqueous foams by using high-melting DAG particles. The obtained foams demonstrated good temperature sensitivity and plasticity, which showed promising application prospects in the food and cosmetic fields.

Phosphatidate (PA) phosphatase, which catalyzes the Mg2+-dependent dephosphorylation of PA to produce diacylglycerol, provides a direct precursor for the synthesis of the storage lipid triacylglycerol and the membrane phospholipids phosphatidylcholine and phosphatidylethanolamine. The enzyme controlling the key phospholipid PA also plays a crucial role in diverse aspects of lipid metabolism and cell physiology. PA phosphatase is a peripheral membrane enzyme that is composed of multiple domains/regions required for its catalytic function and subcellular localization. In this review, we discuss the domains/regions of PA phosphatase from the yeast Saccharomyces cerevisiae with reference to the homologous enzyme from mammalian cells.

Drosophila phototransduction in light-sensitive microvilli involves a metabotropic signaling cascade. Photoisomerized rhodopsin couples to G-protein, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate (PIP2) into inositol trisphosphate, diacylglycerol (DAG) and a proton. DAG is converted into phosphatidic acid by DAG-kinase and metabolized to L-linoleoyl glycerol (2-LG) by DAG-lipase. This complex enzyme cascade ultimately opens the light-dependent transient receptor potential channels, TRP and TRPL. PIP2, DAG, H+ and 2-LG are possible channel activators, either individually or combined, but their direct participation in channel-gating remains unresolved. Molecular interaction with the channels, modification of the channels\' lipid moiety and mechanical force on the channels by changes in the membrane structure derived from light-dependent changes in lipid composition are possible gating agents. In this regard, mechanical activation was suggested, based on a rapid light-dependent contraction of the photoreceptors mediated by the phototransduction cascade. Here, we further examined this possibility by applying force to inside-out patches from the microvilli membrane by changing the pressure in the pipette or pulling the membrane with a magnet through superparamagnetic nanospheres. The channels were opened by mechanical force, while mutant lacking both channels was insensitive to mechanical stimulation. Atomic Force Microscopy showed that the stiffness of an artificial phospholipid bilayer was increased by arachidonic acid and diacylglycerol whereas elaidic acid was ineffective, mirroring their relative effects in channel activity previously observed electrophysiologically. Together, the results are consistent with the notion that light-induced changes in lipid composition alter the membrane structure, generating mechanical force on the channels leading to channel opening.

In Saccharomyces cerevisiae, Pah1 phosphatidate (PA) phosphatase, which catalyzes the Mg2+-dependent dephosphorylation of PA to produce diacylglycerol, plays a key role in utilizing PA for the synthesis of the neutral lipid triacylglycerol and thereby controlling the PA-derived membrane phospholipids. The enzyme function is controlled by its subcellular location as regulated by phosphorylation and dephosphorylation. Pah1 is initially inactivated in the cytosol through phosphorylation by multiple protein kinases and then activated via its recruitment and dephosphorylation by the protein phosphatase Nem1-Spo7 at the nuclear/endoplasmic reticulum membrane where the PA phosphatase reaction occurs. Many of the protein kinases that phosphorylate Pah1 have yet to be characterized with the identification of the target residues. Here, we established Pah1 as a bona fide substrate of septin-associated Hsl1, a protein kinase involved in mitotic morphogenesis checkpoint signaling. The Hsl1 activity on Pah1 was dependent on reaction time and the amounts of protein kinase, Pah1, and ATP. The Hsl1 phosphorylation of Pah1 occurred on Ser-748 and Ser-773, and the phosphorylated protein exhibited a 5-fold reduction in PA phosphatase catalytic efficiency. Analysis of cells expressing the S748A and S773A mutant forms of Pah1 indicated that Hsl1-mediated phosphorylation of Pah1 promotes membrane phospholipid synthesis at the expense of triacylglycerol, and ensures the dependence of Pah1 function on the Nem1-Spo7 protein phosphatase. This work advances the understanding of how Hsl1 facilitates membrane phospholipid synthesis through the phosphorylation-mediated regulation of Pah1.

To investigate the effects of rapeseed diacylglycerol oil (RDG) intake on lipid accumulation and metabolism in C57BL/6J mice, obese mice were fed a high-fat diet in which 45% of the total energy content came from RDG (RDGM group) or rapeseed triacylglycerol oil (RTGM group). This diet intervention was conducted for 12 weeks following the establishment of the obese mouse model. By the end of the experiment, the serum glucose levels of the mice in the RTGM and RDGM groups were 13.0 ± 1.3 mmol/L and 9.7 ± 1.5 mmol/L, respectively. Meanwhile, the serum triglyceride level in the RDGM group was 26.3% lower than that in the RTGM group. The weight-loss effect in the RDGM group was accompanied by a significant decrease in the white adipose tissue (WAT) index. The RDG intervention did not significantly change the antioxidant and anti-inflammatory properties of the rapeseed oil in vivo. The RDG diet improved the liver lipid metabolism abnormalities induced by a high-fat diet, leading to decreased liver damage index values (AST and ALT). Additionally, compared to that in the RTGM group, the expression of the adipogenic genes PPAR-γ and DGAT decreased in both the liver and intestine by 21.7% and 16.7% and by 38.7% and 47.2%, respectively, in the RDGM group. Further, most lipolytic genes in BAT showed no significant change after the RDG intervention. This implies that RDG regulates lipid metabolism by altering the expression of adipogenic genes in the liver, intestine, and adipose tissue, thereby reducing the accumulation of WAT. Furthermore, the RDG diet enhanced gut flora diversity, increasing the relative levels of unclassified Muribaculaceae and decreasing the levels of Dubosiella and Faecalibaculum in the mouse gut, potentially accelerating lipid metabolism. Thus, a three-month RDG diet intervention in obese mice exhibited benefits in regulating the somatotype, serum obesity-related indices, gut flora structure, and lipid metabolism in the adipose tissue, liver, and intestine.

With impaired retinal ganglion cell (RGC) function and eventual RGC death, there is a heightened risk of experiencing glaucoma-induced blindness or other optic neuropathies. Poor RGC efficiency leads to limited transmission of visual signals between the retina and the brain by RGC axons. Increased focus on studying lipid messengers found in neurons such as endocannabinoids (eCBs) has importance due to their potential axonal pathway regenerative properties. 2-Arachidonoylglycerol (2-AG), a common eCB, is synthesized from an sn-1 hydrolysis reaction between diacylglycerol (DAG) and diacylglycerol lipase (DAGL). Examination of DAG production allows for future downstream analysis in relation to DAGL functionality. Here, we describe protocol guidelines for extracting RGCs from mouse retinas and subsequent mass spectrometry analysis of the DAG content present within the RGCs.

Elevated skeletal muscle diacylglycerols (DAGs) and ceramides can impair insulin signaling, and acylcarnitines (acylCNs) reflect impaired mitochondrial fatty acid oxidation, thus, the intramuscular lipid profile is indicative of insulin resistance. Acute (i.e., postprandial) hyperinsulinemia has been shown to elevate lipid concentrations in healthy muscle and is an independent risk factor for type 2 diabetes (T2D). However, it is unclear how the relationship between acute hyperinsulinemia and the muscle lipidome interacts across metabolic phenotypes, thus contributing to or exacerbating insulin resistance. We therefore investigated the impact of acute hyperinsulinemia on the skeletal muscle lipid profile to help characterize the physiological basis in which hyperinsulinemia elevates T2D risk. In a cross-sectional comparison, endurance athletes (n = 12), sedentary lean adults (n = 12), and individuals with obesity (n = 13) and T2D (n = 7) underwent a hyperinsulinemic-euglycemic clamp with muscle biopsies. Although there were no significant differences in total 1,2-DAG fluctuations, there was a 2% decrease in athletes versus a 53% increase in T2D during acute hyperinsulinemia (P = 0.087). Moreover, C18 1,2-DAG species increased during the clamp with T2D only, which negatively correlated with insulin sensitivity (P < 0.050). Basal muscle C18:0 total ceramides were elevated with T2D (P = 0.029), but not altered by clamp. Acylcarnitines were universally lowered during hyperinsulinemia, with more robust reductions of 80% in athletes compared with only 46% with T2D (albeit not statistically significant, main effect of group, P = 0.624). Similar fluctuations with acute hyperinsulinemia increasing 1,2 DAGs in insulin-resistant phenotypes and universally lowering acylcarnitines were observed in male mice. In conclusion, acute hyperinsulinemia elevates muscle 1,2-DAG levels with insulin-resistant phenotypes. This suggests a possible dysregulation of intramuscular lipid metabolism in the fed state in individuals with low insulin sensitivity, which may exacerbate insulin resistance.NEW & NOTEWORTHY Postprandial hyperinsulinemia is a risk factor for type 2 diabetes and may increase muscle lipids. However, it is unclear how the relationship between acute hyperinsulinemia and the muscle lipidome interacts across metabolic phenotypes, thus contributing to insulin resistance. We observed that acute hyperinsulinemia elevates muscle 1,2-DAGs in insulin-resistant phenotypes, whereas ceramides were unaltered. Insulin-mediated acylcarnitine reductions are also hindered with high-fat feeding. The postprandial period may exacerbate insulin resistance in metabolically unhealthy phenotypes.

This research develops diacylglycerol (DAG) based Pickering emulsions with enhanced oxidative stability stabilized by self-assembled quercetin/DAG/β-cyclodextrin (β-CD) complexes (QDCCs) using a one-step agitation method. Influence of DAG content (5%, 15%, 40%, and 80%, w/w) on the self-assembly behavior, interfacial properties, and emulsifying ability of complex particles was investigated. SEM, XRD and ATR-FTIR studies confirmed the formation of ternary composite particles. QDCCs in 80% DAG oil had the highest quercetin encapsulation efficiency (6.09 ± 0.01%), highest DPPH radical scavenging rate and ferric reducing antioxidant property (FRAP). β-CD and quercetin adsorption rates in emulsion with 80% DAG oil were 88.4 ± 2.53% and 98.34 ± 0.15%, respectively. Pickering emulsions with 80% DAG had the smallest droplet size (8.90 ± 1.87 μm) and excellent oxidation stability. This research develops a novel approach to regulate the physicochemical stability of DAG-based emulsions by anchoring natural antioxidants at the oil-water interface through a one-pot self-assembly method.