Studies On The Mechanism Of Put In Later Of Uncaria Hook By HPLC Biomimetic Synthesis Of Monoterpenoid Indole Alkaloids

Part one: In the traditional Chinese medicine (TCM), the uncaria hook is one of the most useful herbs. In the compound prescription of the TCM, uncaria hook usually put in 15 minutes before the other herbs decocted ready. In order to investigate the mechanism of put in later of uncaria hook in compound prescription, two sample of uncaria hook were decocted for 15 and 60 minutes respectively, and the constituents were compared with high performance liquid chromatography. The results showed that three constituents were disappeared and two new constituents were created during the decoction.Part two: Ever since geniposide become available in large quantities in this laboratory, it has been exploited as the starting material instead of secologanin in enantiospecific alkaloid synthesis. In general, the approach has been "biomimetic", following the key steps according to the similar mechanism that occur in nature or which are thought to occur. It also could contribute to elucidation of some aspects of the biosynthesis of these alkaloids, as well as providing a means of obtaining large quantities for pharmocological purposes of those only isolated in minor amounts.The targets of this study are biomimetic synthesis of monoterpenoid indolopyridine alkaloids, a small group of alkaloids composed of trymptamine and substituted pyridine moieties, the latter being derived from a secologanin aglucone unit by insertion of nitrogen. In some cases the full C₁0 unit is present; in others it has been modified by removeal of the ester, vinyl, or other group. It is significant that most of the indolopyridines occur together with structurally related glycoalkaloids whose aglycones constitute obvious precursors for the pyridine units by condensation with ammonia, either endogenous or used in extraction procedures. Subsequent modification can then be rationalized in simple combinations of oxidation, addition of water, β-dicarbonyl or retro-aldol cleavages etc., all of which can occur spontaneously, and hence in many cases the alkaloids are artifacts. The attempt was also made to synthesize dihydrocadambine, an alkaloid isolated from uncaria hook.