Triglycerides, which widely exist in nature, are usually stored in animals and plants in a non hydrated form. They are one of the main forms for animals and human bodies to obtain and store energy, and also the main component of fat in food[1]。The chemical structure of triglycerides is formed by esterification of one molecule of glycerol and three molecules of fatty acids[2]。Vegetable triglycerides are mostly liquid oils, while animal triglycerides are mostly solid fats.Solid and liquid triglycerides are collectively referred to as fats and oils.The physical and chemical properties of triglycerides vary according to the types and chain lengths of fatty acids contained, which directly affects their applications in food industry, biomedicine and other chemical fields.
In organisms, the synthesis and decomposition of triglycerides is the key link of energy metabolism[3]。They not only serve as energy storage and supply materials, but also participate in the construction of cell structure and the regulation of the properties of biological membranes.In the medical field, the level of triglycerides is one of the important indicators to measure human health.High or low levels of triglycerides in the blood may indicate some health problems.In the field of chemical industry, triglyceride is also an important raw material for the synthesis of other chemicals.For example, through hydrolysis or transesterification, triglycerides can be converted into glycerol and fatty acids, both of which are indispensable chemical raw materials in many industrial processes.In addition, triglycerides can also generate fatty alcohol through catalytic hydrogenation, which is widely used in the production of detergents, cosmetics and other daily chemical products.
English name:Trilaurin，1,2,3-Propanetriyl tridodecanoate，1,2,3-Propanetriol tridodecanoate，Glyceryl tridodecanoate[5]
Clinical significance
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The determination of serum triglycerides is a routine item of blood lipid analysis. There are two main sources of triglycerides in plasma:
① Exogeneity: The fat taken from food is absorbed in the intestinal tract by the intestinal mucosa under the action of bile acid and lipase, and triglycerides are synthesized in the epithelial cells of intestinal mucosa.
② Endogenous: The triglycerides synthesized by the body are mainly in the liver, followed by adipose tissue.The main function of triglycerides is to supply and store energy, and also to fix and protect internal organs.
1. Increase: triglyceride is a risk factor for cardiovascular disease[6-7]。Serum triglyceride levels are affected by age, sex and diet.The increase of serum triglyceride can be seen in familial hypertriglyceridemia, which is secondary to some diseases such as diabetes, hypothyroidism, nephrotic syndrome and pancreatitis, atherosclerosis, glycogen storage disease, etc.
2. Decrease: It is found in hyperthyroidism, adrenal cortex dysfunction, severe liver dysfunction, chronic obstructive pulmonary disease, cerebral infarction, malnutrition, congenital α - β lipoproteinemia, etc.
Reference range of normal value:
Normal reference value of serum triglyceride: 0.45~1.69 mmol/L.According to the classification criteria of the 2016 Guidelines for the Prevention and Treatment of Dyslipidemia in Chinese Adults, an appropriate level of fasting (fasting for 12 hours) triglyceride is below 1.70 mmol/L;1.70-2.25 mmol/L means the edge rises; ≥2.26mmol/L is increased[8]。
matters needing attention
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1. The serum triglyceride level is affected by living habits, diet, age, etc., and fluctuates greatly within and between individuals.
2. Try to eat as little as possible lipid containing food 2-3 days before blood collection, and take blood 12 hours on an empty stomach to eliminate and reduce the impact of diet.
prevention and cure
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For patients with hypertriglyceridemia due to definite causes, adjustment and treatment should be carried out according to the causes.Improve your lifestyle first, not oral medication first.Generally, after a period of diet control and increased exercise, the triglyceride index of most patients can fall to the normal level.Those with serious increase of triglyceride (≥ 5.65 mmol/L) should first take drug prevention and treatment.
Lifestyle changes include the following:
① Control your weight.The weight of overweight or obese patients will be reduced by 5% - 10%, which can reduce the triglyceride level by about 20%;
② Eat reasonably.By controlling total dietary calories, controlling total carbohydrate (including rice and flour) and fat intake, and increasing the total intake of vegetables and high-quality protein, the level of triglycerides can be reduced by 20% - 50%;
③ Limit alcohol consumption.Alcoholism is a common cause of elevated triglycerides, and those with severe elevated triglycerides should give up drinking immediately;
④ Exercise moderately.Those with elevated triglycerides should take at least 30 minutes of moderate intensity aerobic exercise every day, at least 5 times a week, including fast walking, cycling, climbing stairs and other forms of exercise. Those who are overweight or obese should further increase the amount of exercise;
⑤ Quit smoking.Smoking can not only increase the level of triglycerides, but also aggravate the harm of serum hypertriglyceridemia to the body. Patients with hypertriglyceridemia should quit smoking[9]。
testing
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Detection of triglycerides and their metabolism is of great significance for understanding the mechanism of metabolic diseases.Traditional methods for detecting lipid metabolism, such as staining, colorimetry, fluorescence and mass spectrometry, have been applied, but each method has its limitations[1]。
dyeing
Various cheap dyes can be used to evaluate the lipid level in tissue or cell culture samples (such as Oil Red O, BODIPY ® dyes[10-11])。The staining results can be observed under a microscope and the progress of fat decomposition or fat generation can be inferred.The method of staining cannot distinguish triglycerides from other neutral lipids.
Colorimetry and fluorescence detection based on microplate
Use mixed enzymes to convert triglycerides or glycerol into detectable colorimetric or fluorescent signals[14]。For example, Sun Cuiping and others[12]Use agar glycoprotein electrophoresis to separate lipoproteins and combine with triglyceride (Tg) enzyme reagent to color, scan out the proportion of Tg in various lipoproteins, and multiply the total Tg concentration in serum to calculate the Tg content in each lipoproteins component.These detection methods can be used for quantitative metabolism and are compatible with various types of samples.
Mass Spectrometry
Spectrometric methods can provide a complete picture of the "lipid group" - all lipid species present in a biological sample.These experiments have produced a large number of quantitative data sets that can be used to describe the process of lipid metabolism.For example, L é v ê que, etc[13]Three categories of triglycerides were separated by non-aqueous reverse phase liquid chromatography, and then were cationic with Ag+. The information of main chain of triglycerides can be identified through mass spectrometry.
At present, there are commercial triglyceride detection kits, so people can know their blood ester content at any time.The principle used is the decomposition of triglycerides by lipoprotein esterase, and then color development through chemical reaction.
