Studies Of Polyphenols From Vitaceous Plants

Polyphenol compounds have received considerable attention in the chemical and biological fields in many plants, owing to their structural complexity as well as their diverse bioactivities. The present dissertation described phytochemical investigation on two vitaceous plants, Parthenocissus.thomsonir and Vitis Labrusca L. This study focused on chemistry and activities of polyphenol compounds from vitaceous plants, including the following four subjects:1. Thirteen polyphenol compounds were isolated from these two vitaceous plants (Virginia Creeper and Xinjiang wine grape). The structures of the compounds were elucidated by spectroscopic analysis, including MS and NMR experiments. Counter-current chromatography in combination with step-wise elution mode was developed and applied to the preparative separation and purification of two antioxidative isomers of resveratrol dimer from the crude samples of Xinjiang wine grape in a one-step separation.2. A facile method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/(-)ESI-MSn) in the online has been established for the identification of ten isomers of resveratrol dimers and their analogs in Xinjiang wine grapes. Among them, three are tentatively identified as new compounds. MSn experiments on the [M-H]-ions provide abundant structural information, especially regarding the key product ions, m/z333and369(385in compound3), which can distinguish whether or not the compound identified is the key structure of the isomer of resveratrol dimer. And based on characteristic UV absorptio, three pairs of the trans-, cis-isomers could be identified by HPLC/DAD-UV spectra3. The ROS scavenging effects of Scirpusin A, a hydroxystilbene dimer from wine grapes in Xinjiang, were evaluated by the EPR spin-trapping technique. The results from our study indicated Scirpusin A is a selective1O2quencher, but not an effective OH or O2-scavenger. And it was found that singlet oxygen induced pBR322DNA strand breakage and its inhibition by Sirpusin-A were assessed by agarose gel electrophoresis analysis.4. Using MTT assay to detect thirteen polyphenol compounds from vitaceous plants against the growth of G.citri-aurantii in vitro, the results showed that pterostilbene exhibited much stronger inhibition. The results obtained by scanning electron microscopy and transmission electron microscopy showed that the morphology and inner structure of the G citri-aurantii treated with the pterostilbene changed obviously. Some of the cells were made abnormality or lysed. Obviously, the lipid membranes were destroyed, and then they can penetrate into the cells and destruct cell organelles and cytoskeleton. Experiment further clarify the molecular mechanism of action, we demonstrated the binding properties exerted by the pterostilbene on DNA and RNA of G.citri-aurantii fungal cells. Results showed that DNA and RNA of the G.citri-aurantii fungal cells were degraded by the pterostilbene. And then the metabolic process of fungi was destroyed and the fungi were killed. Moreover, five differentially expressed genes of apoptosis of fungi were studied by RT-PCR in the dissertation, the results indicated that pterostilbene exposure up-regulated the expression of genes involved in five genes (RLM1, RTG1, RTG3, MET3and GRP78), among which RLM1, RTG1were significantly up-regulated.