Investigation On Bioactive Substances Of Three Plants And One Fungus

Natural product chemistry method, mainly consisting of automated FlashMaster chromatography and HPLC-DAD-ESI-MS systems, has been applied to the generation and analysis of a ’drug-like’ natural product library---Flash fractions for drug discovery and chemical biology research. Three plants (Gentiana dahurica Fisch., Arctostaphylos pajaroensis and Capparis spinosa L.) together with the edible fungus Xylaria nigripes (K1.) Sacc., have been phytochemically investigated. A total of sixty-five naturally occurring compounds were obtained by using column chromatography (CC) over silica gel, MCI gel, Sephadex LH-20, and semi-preparative HPLC. Forty-six different compounds were characterized as fifteen triterpenoids, five iridoid glycosides, six alkaloids, five sesquiterpenoids, four steroids, four flavonoids and isoflavonoids, two glycosides, one coumarin, one furfural, two organic acids and one phenylpropanoid. Among them, three were new, and another thirty-nine were isolated for the first time from the corresponding plant. Their structures were identified on the basis of extensive spectroscopic methods (especially LR-/HR-ESIMS,1H,13C-NMR and 2D NMR), chemical transformations and single-crystal X-ray diffraction analysis. Biological tests revealed that some compounds exhibited moderate cytotoxicity, and several pentacyclic triterpenoids were further found to be the anti-cancer effective substance of G. dahurica and A. pajaroensis. The technique of high performance liquid chromatography-electrospray ionization time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) has been developed for the rapid determination of complex components in the above selected crude materials.The main research topics in the dissertation are outlined as follows:(1) Generation and analysis of natural product library---Flash fractionsNatural product chemistry methods (mainly include automated FlashMaster chromatography and HPLC-DAD-ESI-MS) were utilized to generation and analysis of natural product library (Flash fractions) from herb medicines. Up to now, the natural product libraries consist of 2226 Flash fractions from 106 biologically selected herb medicines.(2) Studies on chemical constituents and bioactivities of three plant materialsSixteen compounds including seven pentacyclic triterpenoids (2.1,2.4-2.9), five iridoid glycosides (2.2,2.3,2.10-2.12) and four other compounds (2.13-2.16) were isolated from G. dahurica Fisch. Among them, three (2.1-2.3) were new, while nine compounds (2.4-2.12) were reported from this plant for the first time. Most compounds were tested for their cytotoxic effects, and compounds 2.6-2.9 were found to show moderate cytotoxicity against MCF-7 human breast cancer cells, SK-Hepl hepatocarcinoma cells, and U20S osteosarcoma. In addition, corosolic acid (2.7) could effectively block Store-Operated Calcium Entry (SOCE).A. pajaroensis has never been phytochemically and pharmacologically investigated. In this study, twelve compounds (3.1-3.12) were isolated from the organic extract and MeOH extract of A. pajaroensis. The isolated compounds were tested against the human hepatocarcinoma SNU739 cancer cell line, the human neuroblastoma SHSY-5Y cell line, the human gastric carcinoma NUGC-3 cancer cell line and the human breast MCF-7 cancer cell line. Only compounds 3.2 and 3.4 were found to show moderate cytotoxicities.The fruits of C. spinosa L. have been studied. One alkaloid (4.1), five sesquiterpenoids (4.2-4.6) and four other compounds (4.7-4.10) were isolated. Compounds 4.2-4.5 were obtained from this plant for the first time.(3) Investigation on chemical constituents and anti-depression effect of X. nigripesEleven known compounds (5.1-5.11) were obtained and determined from X. nigripes (K1.) Sacc. The structures included spiro-alkaloids, steroids and isoflavonoids. Some crude fractions and purified compounds could enhance the expression leve of the brain derived neurophic factor (BDNF).(4) Analysis of compounds in crude extracts using HPLC-DAD- ESI-MS techniqueThe HPLC-DAD-ESI-MS method was developed for the analysis of complex components of G. dahurica, A. pajaroensis and C. spinosa. The main components were primarily identified by comparison of the tR values, UV spectra and mass spectra with reported literature data.