Developing Study On HPLC Fingerprint Of The Water Extracts Of Herba Pogostemonis

Herba Pogostemonis is a Chinese drug used most commonly in China. In Traditional Chinese Medicine, this herba is considered as having follow indications:to eliminate dampness from the middle jiao, to regulate the middle jiao, to eliminate summer-heat and expel the affection of exogenous summer-heat and dampness.In the course of evaluating the quality of this traditional herb, we found that the water extracts have more distinctive bioactivities;but most of the constituents were unknown, especially the water-soluble compounds.However, further research results showed that, the water extract of Herba Pogostemonis have the more notable bioactivities then patchouli oil. So, further study of the water-soluble components of Herba Pogostemonis is imperative, so as to clarify its efficacy material basis, to establish a scientific quality standards for the treatment guarantee the safety and effectiveness. In the unknown condition of effective constituents of Herba Pogostemonis, the application of HPLC chromatographic fingerprint technology will be very useful to control the quality of Herba Pogostemonis. On the basis of the previous research work, this paper , HPLC chromatographic fingerprints of the different polarity extracts of the water extract of Herba Pogostemonis from different regions, different harvest time, different storage time and different medicinal parts were compared. The standard HPLC fingerprints used to reflect the overall compositions, to evaluate the quality of Herba Pogostemonis and to provide the basis for the identification of it were established.Three different polar solvents , chloroform, acetoacetate and n-butanol,were selected to extract differant polarity compounds of the water extraction of Herba Pogostemonis, the chromatographic conditions for each extract part were tested, and the fingerprints of different polarity extracts of Herba Pogostemonis were established. the absorption peak of pogostone in the chloroform part was identified , and the absorption peaks of vanillic acid, protocatechuic acid and apignein-7-0-β-D-glucoside were also identified in acetoacetate part. The method is accurate and reproducible, and the analytical samples are stabile in 48 hrs.The differences of the HPLC fingerprint of Herba Pogostemonis from various places of production, from different harvest time and storage period ,from different medicinal parts were compared. The results showed that the chromatographic similarity of Herba Pogostemonis cultivated in tow regions of Gaoyao and Shipai,when the latter was used as the standard, is more than 0.9,but the chromatographic similarity of Herba Pogostemonis cultivated in another tow regions of Wuchuan and Wanning were different. Their similarity of the different polarity parts is obvious different as follows: 0.854 and 0.829 in the extraction of chloroform, 0.820 and 0.948 in the extraction of acetoacetate, 0.943 and 0.925 in the extraction of n-butanol , the difference of higher polarity parts is small. The HPLC fingerprints of Herba Pogostemonis collected from different harvest time and different storage period were compared, the results showed that the difference of the HPLC fingerprint obtained from different harvest period were less except the contents of compounds and thier similarity of different polarity extracts is more than 0.9, but storage time has a greater influence on components of water extract of Herba Pogostemonis, especially the components of high polarity, for example, HPLC fingerprints of Herba Pogostemonis collected from Gaoyao county in December of 1997 than in December of 2007 were similar of parts in chloroform, but were obvious different in the extracts of acetoacetate and n-butanol ,their similarity were respectively 0.921, 0.422, 0.088, which showed that similarity increased with the degree of polarity. The HPLC fingerprints of water extracts of the different medicinal parts were compared, the results showed that the fingerprints of three polarity extracts of leaves than with stems is more abundant in components and contents. The above research results could be used for the identification of the crude drug and the evaluation of its quality.