Synthesis And Properties Of Functional Triterpenoid Molecules

Triterpenoids, which mainly comes from natural medicinal plants, is used for thetreatment of anti-inflammation, anti-virus, anti-tumor, anti-bacteria and anti-fungal.Due to its characteristic stereostructures, biological activities and biocompatibility, todesign and synthesize new functional molecules with triterpenoid chiral skeleton issignificant in the potential drug delivery, molecular/ion recognition and medicalmaterials and so on. In this dissertation, we focused on the design and synthesis of aseries of novel functional triterpenoids molecules. Their structures were identified bymeans of spectroscopic methods and the preliminary bioactivity was screened as wellas their gel abilities and molecule/ion recognition properties were studied. The majorwork is as follow:A series of ring-opened and heterocyclic derivatives of glycyrrhetinic acid andoleanolic acid were designed and synthesized. It showed that the number and thelocation of hydroxyl groups played an important role in inhibiting HepG-2cells,while the ring-opened compounds had almost no cytotoxic activity.2,3-dihydroxyimino oleanolic acid was found to form the strong organogel inchlorinated and aromatic solvents and it was confirmed that the driving force for thegel formation was intermolecular hydrogen bonds by variable temperature infrared,nuclear magnetic resonance and pH response experiment. Furthermore, chiralassembly was observed in the gel by circular dichroism. Fan-shaped C3moleculeswere designed and synthesized as well as urea-bridged biological conjugatemonomers and dimers containing glycyrrhetinic acid and oleanolic acid. The resultsindicated that fan-shaped C3molecules with three glycyrrhetinic acid units couldform weak gel in THF-Methanol mixed solvents, while most of the other compoundswere assembled into solid spheres.Triterpenoid-based molecular tweezers and cyclic dimers were synthesized using"click reaction", and molecular tweezers were found to selectively identify themercury ion by nuclear magnetic resonance and UV-visible spectrum. At the sametime, cyclic dimmers also could identify the fluoride selectively through C-H…F hydrogen bond interactions which involved the delocalization of proton in methylene.A novel glycyrrhetinic acid conjugate containing uracil and2,6-diaminopyridineunits was initially synthesized which could self-assemble into a cyclic dimer throughhydrogen bonds by nuclear magnetic resonance titration. It could recognize polarmolecule in aprotic solvents.