| Gamboge, a dry gum resin, is derived from the plants of Garcinia morallla Desr and Garcinia hanburyi Hook. F. Gamboge was used as laxative as well as a hemostatic.The plants are distributed cultivated in the tropics, mainly in India, Thailand, and in China’s provinces of Guangdong, Fujian, Hainan and other regions.This paper, first of all, reviewed the raw gamboge of resources distribution, processing method, chemical constituents and pharmacological activities.Secondly, the chemical composition of gamboge was studied, and then GA and GNA were selected from its chemical compositions as the reference substance.Thirdly, the stability of the GA and GNA was studied.The last but not the least, the preparation process of the GA and GNA was studied, which can provide reference for preparation.Using silica gel, reverse phase silica gel, Sephadex LH-20, preparation of HPLC and semi-preparation of HPLC as the method of isolation,12compounds were isolated from methanol extract of gamboge, which the chemical structures of9compounds from the12compounds was identified by the spectral methods and literature reports.They are respectively:gambogic acid (1),(2R)-gambogic acid (2),(2S)-gambogic acid (3), gambogenic acid (4), a-morellic acid (5),β-morellic acid (6),(2R)-isogambogic acid (7), Methyl-9-dihydromorellate (8), gaudichaudic acid (9).On the basic of consulting literature, combining the specificity, toxicology, bioactivity, content and stability, the gambogenic acid and gambogic acid were finally choosed as the chemical reference substance of the gamboge.According to the method of the Chinese Pharmacopeia (2010, Edition), gambogenic acid and gambogic acid were studied on the test of high temperature, high humidity, illumination test, accelerated test, long-term stability test in different environment. The results are as following. Under the condition of40℃placed10days, the purity of the GA and GNA is less than98%; under the condition of the humidity92.5%for10days, the changes of their purity are very little, but their moisture absorption are more than5%of theirself weight; when they were placed under the condition of humidity of75%for10days, their weight did not change.But the purity of neo-gambogic acid is below98%and the change of purity of the gambogic acid is not obvious.Under the condition of oxidation they were unstable;however they were very stable under the condition of light. After the accelerated test for the gambogenic acid and gambogic acid were carried out for3months, the results showed that they were very stable under the condition of (6+ 2)℃;however they changed under the condition of (25+2)℃. According to their long-term test for3months, the changes of both ware very little. Therefore, the gambogenic acid and gambogic acid should at the condition of low temperature, avoiding light, and airtight conditions, especially for the gambogenic acid,because in the process of experiment, it was found that the gambogic acid ware more stable than the gambogenic acid.Using the extraction yield of gambogenic acid and gambogic acid as the index, the method of ultrasonic extraction, diacolation method and the reflux method were studied.The results showed that the extraction yield of reflux extraction was higher than the other two methods;therefore the refluxing extraction was selected as the best method to extract GNA and GA from gamboge.In this condition,the extraction yield of GNA is more than10%and the extraction yield of GA is more than30%. Then the orthogonal test was used to optimize the purification of GNA and GA by semi-preparative HPLC,finally the optimal condition was confirmed as followed, which is acetonitrile-0.1%acetic acid aqueous solution (80%:20%) as mobile phase, flowing rate of2.5mL/min, sample volume of0.3mL, sample concentration is0.075g/mL, detection wavelength of310nm. |
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