What Are Glycolipids?

Glycolipids are lipid compounds that are widely present in various organisms. Glycolipids in nature can be divided into two major groups according to the types of alcohol groups in their components: glyceroglycolipids and sphingoglycolipids. Glycosylated glycerolipids are called glyceroglycolipids and are found in the nervous tissues, plants and microorganisms of animals. They are the main glycolipids in plants, and they are also the membrane of some bacteria, especially Gram-positive bacteria. Common ingredients ^[1] .

Glycolipid refers to a lipid compound containing a glycosyl ligand. It is a class of amphiphilic molecules and is widely present in living organisms.

Glycolipids can be divided into 4 types according to the lipid part:

(1) Including

For the separation and purification of glycolipid compounds, macroporous adsorption resin method, high-performance thin-layer chromatography and column chromatography are commonly used at home and abroad.

Glycol lipid macroporous adsorption resin method

The macroporous adsorption resin method is mainly used for the coarse separation of samples. The obtained product is a glycolipid mixture, and it is difficult to obtain a single compound. For example, Cao Dongxu et al. ^[3] used carp minced fish as a glycolipid material, separated 90% ethanol extract with HP-20 macroporous adsorption resin, and eluted with 90% ethanol and chloroform to obtain 90% ethanol. The eluate was separated with HP-20 macroporous adsorption resin, followed by elution with 70% ethanol and 95% ethanol. The 95% ethanol eluate was collected and concentrated to obtain a glycolipid concentrate.

Glycolipid high performance thin layer chromatography

Murakami et al. Used fresh leaves of Thai herbal lime as raw materials, extracted the obtained ethyl acetate, and performed dextran gel C-100 column chromatography. The eluent was an acetone / toluene solution with successively increased acetone concentrations. 60-80% acetone eluate. Then, the eluate was subjected to reversed-phase silica gel column chromatography, and methanol / water (9: 1, v /, r), methanol / acetonitrile / water (16: 4: 5, v / v ) were sequentially used as eluents Agent to obtain a mixture containing glyceroglycolipids DLGG and LPGG, and further subjected to high-performance thin layer chromatography to prepare a silica gel plate for separation, to obtain glyceroglycolipid monomers DLGG and LPGG. High-performance thin-layer chromatography usually requires a large number of repeated extractions to obtain a single component of glycolipids, and the amount of extraction is small, which is difficult to meet the further research of glycolipid structure identification and biological activity.

Glycolipid chromatography

In recent years, column chromatography is a widely used separation method for glycolipid separation. For example, Chia-Chung Hou and others used folk showa as raw material, extracted the ethyl acetate phase, and used chloroform. Methanol was used as eluent. Fraction 8 was obtained by forward silica gel column chromatography. Fraction 8 was taken and C18 reversed phase silica gel column chromatography was performed again. 95% methanol was used as eluent to obtain glycerol glycolipid rich in linolenic acid. ingredient.

Although column chromatography can process a large number of samples, it has the disadvantages of serious irreversible adsorption, low separation efficiency, long time consumption, and large solvent consumption.

Because the differences between the same class of glycolipids are only reflected in the differences in the composition of acyl fatty acids, the properties of molecular chargeability and molecular polarity are very similar, it is difficult to separate a single glycolipid from a large number of mixed glycolipids using existing methods. Therefore, it is not possible to buy a completely single natural standard glycolipid from the chemical market. Major chemical companies and companies that specialize in providing lipid standards can only provide TLC-level mixed glycolipid standards. Only by studying the content structure of each component in the mixed glycolipid clearly can we make the related research (such as biological activity) more in-depth. Therefore, it is necessary to find a new method with low energy consumption, high separation efficiency, and large-scale extraction of a single component of glycolipids in order to meet the needs of neurobiology research and clinical application research.

Countercurrent chromatography is a liquid-liquid chromatography technology developed in the past thirty years ^[4] . One of its advantages is that it does not use solid adsorption materials, which can avoid the disadvantages of irreversible adsorption and sample degradation in other chromatography techniques; the other advantage is that it can completely recover the sample. As a kind of separation technology in the laboratory, counter-current chromatography has shown unparalleled advantages of high-performance liquid chromatography, such as low sample purity requirements, large injection volume, and simple operation.