Ligustrum Lucidum In The Split Ring Iridoid Glycosides

Fructus Ligustri lucidi (Chinese name Nvzhenzi) is from the dried fruits of Ligustrum lucidum Ait., family Oleaceae, which is a kind of traditional Chinese medicine, sweet or bitter in flavor, cold in nature. It was firstly recorded in the earliest Chinese pharmaceutical monograph Shen Nong's Herbal (about AD200) and ranked in the first grade. It has the effect of nourishing liver and invigorating the kidney, and promoting the eyesight and blackening the hair. Use for dizziness and tinnitus, soreness and weakness of waist and knee, manifestations of blurred vision and weakness of eyesight, premature whitening of hair.In many related reports, liposoluble triterpenoid was considered as the predominant ingredient in Fructus Ligustri lucidi. Oleanolic acid, regarded as the most important active substance has been investigated deeply and systematically in both its chemistry and pharmacological research. Meanwhile many quantitative analysis methods for it have been set up. However according to Chinese traditional custom, Fructus Ligustri lucidi should be boiled with water before drug regimen. Consequently the water-soluble portion of Fructus Ligustri lucidi could not be ignored.After 20 century the world research indicate that besides the low-polar constituent oleanolic acid, Fructus Ligustri lucidi also contains many water-solubility components, such as high-contents iridoid glucosides. Iridoid glucosides have many biological functions like protect liver and gallbladder, anti-hepatic fibrosis, antibiosis and dephlogisticate, subdue blood-fat, cut down blood-sugar, degrade viscosity, reinforce immunological regulation, etc. We need to give more attention to the iridoid glucosides, which could also reflect the internal quality of Fructus Ligustri lucidi.Here, we study the extraction and separation of the constituents in FructusLigustri lucidi. By using solvent extraction, column chromatography on silica gel ,especially preparative HPLC, we got five chemical compounds, and the structures ofthem were authenticated by means of spectroscopy (UV, IR, ¹³C NMR, ¹H NMR). They are oleanolic acid, ursolic acid, nuezhenoside, G13 and D-glucose. Two of them were secoiridoid glucosides (nuezhenoside and G13).In order to get further messages of the secoiridoid glucosides in Fructus Ligustri lucidi, we determined two of them (nuezhenoside and G13) in samples from different places and acquisition times by HPLC using double wavelength and gradient elution. From the experiment we found that nuezhenoside and G13 were the two major secoiridoid glucosides in the water-soluble portion of Fructus Ligustri lucidi. And the results of content determination (nuezhenoside and G13) of samples from different places varied greatly. For example, the highest contents for nuezhenoside and G13 were 1.089 and 0.478%, while the lowest contents were 0.026 and 0.013%, respectively. This might be caused by different species sources and different preparation methods, etc. The tendency of the content variation in the fruits was coincident with in the leaves. This experiment led up to the fact that from the beginning to the middle of November the content of nuezhenoside and G13 reached the maximum.Meanwhile, By studying the migration behavior of the above two secoiridoid glucosides on capillary zone electrophoresis (CZE). Subsequently a quick, accurate capillary electrophoresis method for quantitative analysis of nuezhenoside and G13 was developed. In our experiment, we found that the power of hydrogen, concentration of borax and the separation voltage were three main factors. The power of hydrogen influences the migratory behavior of different materials greatly. Higher concentration of borax can get better resolution. But it probably led up to the fact that retention time will be prolonged and the peak shape will be critically influenced. Sometimes higher separation voltage is the same.Here we also have done some preliminary researches about the antioxidant and antibacterial activities of nuezhenoside and G13. The results revealed that these ingredients showed significant antioxidant activities. A positive correlation existed between total content and antioxidant activity. G13 had shown higher antioxidant activity than nuezhenoside. It implied that the structure of secoiridoid glucoside was positive to antioxidant activity. Otherwise, the results could promote the deep research of the antioxidant mechanism in Fructus Ligustri Lucidi.So, we regarded nuezhenoside and G13 as the typical water-soluble ingredients in Fructus Ligustri Lucidi and establish the quality control system. All the works are prepared for the revision of Chinese Pharmacopeia in 2010.