Phosphatidate phosphatase (PAP) catalyzes the penultimate step in the synthesis of triacylglycerol and regulates the synthesis of membrane phospholipids. There is much interest in this enzyme because it controls the cellular levels of its substrate, phosphatidate (PA), and product, DAG; defects in the metabolism of these lipid intermediates are the basis for lipid-based diseases such as obesity, lipodystrophy, and inflammation. The measurement of PAP activity is required for studies aimed at understanding its mechanisms of action, how it is regulated, and for screening its activators and/or inhibitors. Enzyme activity is determined through the use of radioactive and nonradioactive assays that measure the product, DAG, or Pi However, sensitivity and ease of use are variable across these methods. This review summarizes approaches to synthesize radioactive PA, to analyze radioactive and nonradioactive products, DAG and Pi, and discusses the advantages and disadvantages of each PAP assay.

Protein kinase C (PKC) and Protein kinase D (PKD) isoforms can sense diacylglycerol (DAG) generated in the different cellular compartments in various physiological processes. DAG accumulates in multiple organs of the obese subjects, which leads to the disruption of metabolic homeostasis and the development of diabetes as well as associated diseases. Multiple studies proved that aberrant activation of PKCs and PKDs contributes to the development of metabolic diseases. DAG-sensing PKC and PKD isoforms play a crucial role in the regulation of metabolic homeostasis and therefore might serve as targets for the treatment of metabolic disorders such as obesity and diabetes.

The majority of the epidemiological evidence over the past few decades has linked high intake of fats, especially saturated fats, to increased risk of diabetes and cardiovascular disease. However, findings of some recent studies (e.g., the PURE study) have contested this association. High saturated fat diets (HFD) have been widely used in rodent research to study the mechanism of insulin resistance and metabolic syndrome. Two separate but somewhat overlapping models-the diacylglycerol (DAG) model and the ceramide model-have emerged to explain the development of insulin resistance. Studies have shown that lipid deposition in tissues such as muscle and liver inhibit insulin signaling via the toxic molecules DAG and ceramide. DAGs activate protein kinase C that inhibit insulin-PI3K-Akt signaling by phosphorylating serine residues on insulin receptor substrate (IRS). Ceramides are sphingolipids with variable acyl group chain length and activate protein phosphatase 2A that dephosphorylates Akt to block insulin signaling. In adipose tissue, obesity leads to infiltration of macrophages that secrete pro-inflammatory cytokines that inhibit insulin signaling by phosphorylating serine residues of IRS proteins. For cardiovascular disease, studies in humans in the 1950s and 1960s linked high saturated fat intake with atherosclerosis and coronary artery disease. More recently, trials involving Mediterranean diet (e.g., PREDIMED study) have indicated that healthy monounsaturated fats are more effective in preventing cardiovascular mortality and coronary artery disease than are low-fat, low-cholesterol diets. Antioxidant and anti-inflammatory effects of Mediterranean diets are potential mediators of these benefits.

Diacylglycerol (DAG) is a world leading anti-obesity functional cooking oil synthesized via structural modification of conventional fats and oils. DAG exits in three stereoisomers namely sn-1,2-DAG, sn-1,3-DAG, and sn-2,3-DAG. DAG particularly sn-1,3-DAG demonstrated to have the potential in suppressing body fat accumulation and lowering postprandial serum triacylglycerol, cholesterol and glucose level. DAG also showed to improve bone health. This is attributed to DAG structure itself that caused it to absorb and digest via different metabolic pathway than conventional fats and oils. With its purported health benefits, many studies attempt to enzymatically or chemically synthesis DAG through various routes. DAG has also received wide attention as low calorie fat substitute and has been incorporated into various food matrixes. Despite being claimed as healthy cooking oil the safety of DAG still remained uncertain. DAG was banned from sale as it was found to contain probable carcinogen glycidol fatty acid esters. The article aims to provide a comprehensive and latest review of DAG emphasizing on its structure and properties, safety and regulation, process developments, metabolism and beneficial health attributes as well as its applications in the food industry.

Mango kernel fat (MKF) has been reported to have high functional and nutritional potential. However, its application in food industry has not been fully explored or developed. In this review, the chemical compositions, physical properties and potential health benefits of MKF are described. MKF is a unique fat consisting of 28.9-65.0% of 1,3-distearoyl-2-oleoyl-glycerol with excellent oxidative stability index (58.8-85.2 h at 110 °C), making the fat and its fractions suitable for use as high-value added food ingredients such as cocoa butter alternatives, trans-free shortenings, and a source of natural antioxidants (e.g., sterol, tocopherol and squalene). Unfortunately, the long period of dehydration of mango kernels at hot temperature results in the hydrolysis of triacylglycerols. The high levels of hydrolysates (mainly free fatty acids and diacylglycerols) limit the application of MKF in manufacturing these food ingredients. It is suggested that the physico-chemical and functional properties of MKF could be further improved through moderated refining (e.g., degumming and physical deacidification), fractionation, and interesterification.

Diacylglycerol kinase (DGK) is an enzyme that converts diacylglycerol to phosphatidic acid. To date, 10 isoforms of DGKs (α, β, γ, δ, ε, ζ, η, θ, ι, and κ) have been identified in mammals, and these DGKs show characteristic expression patterns and roles. The expression levels of DGKs are comparatively higher in the central nervous system than in other organs and may play several important roles in regulating higher brain functions. Currently, many studies have been performed to reveal the roles of DGKs by knocking down or overexpression of DGKs in vitro. Additionally, knockout or overexpression mice of several DGKs have been generated, and phenotypes of these mice have been studied. In this review, we discuss the roles of DGKs in the central nervous system based on recent findings in genetic models.

Food oils are primarily composed of triacylglycerols (TAG), but they may also contain a variety of other minor constituents that influence their physical and chemical properties, including diacylglycerols (DAG), monoacylglycerols (MAG), free fatty acids (FFA), phospholipids (PLs), water, and minerals. This article reviews recent research on the impact of these minor components on lipid oxidation in bulk oils and oil-in-water emulsions. In particular, it highlights the origin of these minor components, the influence of oil refining on the type and concentration of minor components present, and potential physicochemical mechanisms by which these minor components impact lipid oxidation in bulk oils and emulsions. This knowledge is crucial for designing food, pharmaceutical, personal care, and other products with improved stability to lipid oxidation.

Diacylglycerol oil is an edible oil with taste and usability characteristics comparable to naturally occurring oils. The objective of this review is to examine literature on diacylglycerol oil to assess its safety-in-use. Feeding rats with unheated or heated diacylglycerol oil at levels up to 5.5% in diet for 90 days did not cause any toxic effects. In chronic studies, dietary administration of diacylglycerol oil (up to 5.3%) to rats for 2 years or at 9.5% to Beagle dogs for 1 year had no adverse effects. Genotoxicity studies of unheated and heated diacylglycerol oil did not reveal any genotoxic effects. Carcinogenicity studies in rodents demonstrate that diacylglycerol oil is non-carcinogenic. In a two-generation reproductive and developmental toxicity study, gavage administration of diacylglycerol oil at dose levels of 5.0 ml/kg body weight/day did not reveal any adverse effects. In several human clinical investigations, administration of diacylglycerol oil at levels up to 0.5 g/kg body weight/day for up to 1 year did not cause adverse effects. Collectively, there is sufficient qualitative and quantitative scientific evidence available from animal and human studies suggesting that intake of diacylglycerol oil is safe for human consumption when used in a manner similar to other edible oils.

The detailed analysis of lipids, especially phospholipids, has become progressively important, since these molecules represent intercellular messenger molecules and are involved in a number of diseases. Therefore, the analysis of the lipid pattern of blood, for example, may also be useful as a diagnostic tool. Unfortunately, suitable methods of phospholipid analysis are often time-consuming and tedious, since most of them include a variety of separation and derivatization steps. Methods allowing lipid analysis in a single step would be highly useful. The aim of this review is to show that high resolution 31P NMR spectroscopy is a convenient and precise analytical tool for the phospholipid analysis of extracts from biological samples (tissues and body fluids). The first part of this review discusses the physiological relevance of individual kinds of phospholipids and related, established analytical techniques for their investigation. The second part contains an overview on the requirements for 31P NMR to improve spectral resolution and sensitivity, its capabilities and its limitations. In the third part, we discuss the application of 31P NMR to the most important phospholipid classes, as well as different tissue and body fluid extracts. The article concludes with a brief look at future developments and potential applications of this technique.

Among tumoral resistances, multidrug resistance (MDR) is characterized as cross-resistance to a variety of structurally and functionally unrelated drugs such as vinca alkaloids, colchicine, and anthracyclines. Decreased drug cellular influx and increased cellular ability for drug extrusion are the main mechanisms involved in MDR. Two plasma membrane proteins, p-glycoprotein (p-gp) and the multidrug resistance-associated protein (MRP), act as ATP-dependent cellular efflux. Furthermore, protein kinase C (PKC) is also central to MDR. The present study reviews the role of cholesterol and other lipids in the reduction of drug influx and drug binding to cellular membranes. The study also examines the effect of lipid composition on p-gp activity. Concerning the role of PKC in MDR, two phospholipases involved in diacylglycerol (DG) production increase in MDR cells. These are phosphatidylinositol-4, 5-bisphosphate-specific phospholipase C and phosphatidylethanolamine-specific phospholipase D. A positive feedback mechanism for DG production which includes these phospholipases, a phosphatidylcholine-specific phospholipase C and a phosphatidylcholine-specific phospholipase A2 has also been suggested. The hypothesis of exocytic involvement in MDR is reviewed, and some lipid changes found in MDR cells are interpreted according to those fusogenic properties normally involved in exocytic transport. Also, the possible role of lipid mediators, such as phosphatidic acid and platelet-activating factor, is examined.