芦笋皂苷的抗肿瘤作用研究进展

芦笋是一种常见蔬菜,富含多种营养物质,在多种疾病的预防和治疗中发挥良好的药理效应。芦笋中的甾体皂苷是其生物活性的主要表现物质,现已从芦笋中分离出的皂苷单体有19种。本文概述了它们的来源及结构,对其中已被报道的几种皂苷单体在肿瘤预防和治疗方面的作用、机理及研究进展加以综述,为进一步分离新的芦笋皂苷单体及其对肿瘤的预防和治疗提供参考。     

Molecular characterization and evaluation of plant litter-associated fungi from the spring ‘grazing corridor’ of a sheep herd vulnerable to alveld disease

This study sample and identify species of fungi on withered vegetation in the spring 'grazing corridor' from infields to Narthecium bogs for a sheep herd almost chronically vulnerable to phototoxic disease. Hepatogen photosensitizing disorders like alveld attack grazing sheep, especially lambs, in various parts of the world. It has been hypothesized that saponin metabolites in the monocotyledonous plant Narthecium ossifragum causes the disorder in Norway, however, this has not been verified. Thus, the search for other causal agents or saponin cofactors (the cofactor hypothesis) has been intensified, and endophytic poisonous fungi associated with dead N. ossifragum leaves and grasses are among the prime suspects. The fungal diversity was targeted by obtaining axenic cultures from surface-sterilized plant material, with subsequent DNA isolation, PCR, and sequencing of the ITS nrDNA region. The taxonomic affinities of the obtained sequences were thereafter explored by similarity searches against the public access sequence database EMBL/GenBank/DDBJ. Among the spectrum of identified taxa were representatives of Cladosporium, Fusarium, Penicillium, and Trichoderma, all of which are well known as potential producers of toxins. A possible involvement of these toxic species in the etiology of alveld is evaluated and discussed.     

Quality evaluation of Astragali Radix using a multivariate statistical approach

The quality of 43 Astragali Radix samples collected in China and Mongolia was evaluated using multivariate statistical analysis of data obtained from liquid chromatography-ion trap-time of flight (LC-IT-TOF) mass spectrometry. The samples were classified into four characteristic groups and most of the marker compounds were identified by elemental composition data and the results of MS/MS analysis. The approach provides useful information and gives an overview of the difference between crude drugs originating from different production environments and the genetic nature of the medicinal plants. In addition, the ease with which particular marker compounds could be identified and the effectiveness of the comparison by means of multivariate statistics, such as principal component analysis (PCA), indicates that this method could be utilized for the establishment of standardization and quality control procedures for crude drugs.     

Synthesis of a tetra- and a trisaccharide related to an anti-tumor saponin “Julibroside J<Subscript>28</Subscript>” from <Emphasis Type="Italic">Albizia julibrissin</Emphasis>

Simple and convergent synthesis of a tetra- and a trisaccharide portions of an antitumor compound Julibroside J₂₈, isolated from Albizia julibrissin, that showed significant in vitro antitumor activity against HeLa, Bel-7402 and PC-3M-1E8 cancer cell lines is reported. The tetrasaccharide has been synthesized as its p-methoxyphenyl glycoside starting from commercially available d-glucose, l-rhamnose and l-arabinose. The trisaccharide part has been synthesized from commercially available N-acetyl d-glucosamine, d-fucose and d-xylose using simple protecting group manipulations. Sulfuric acid immobilized on silica has been used successfully as a Brönsted acid catalyst for the crucial glycosylation steps.     

Synthesis of oleanolic acid saponins mimicking components of Chinese folk medicine Di Wu

3,28-Di-O-rhamnosylated oleanolic acid saponins, mimicking components of Chinese folk medicine Di Wu, have been designed and synthesized. One-pot glycosylation and ‘inverse procedure’ technologies have been applied thus significantly simplifying the preparation of desired saponins. The cytotoxic activity of compounds 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] ester (3), 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl- (1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] ester (4), 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[α-l-rhamnopyranosyl] ester (5), and 3-O-[α-l-rhamnopyranosyl]oleanolic acid 28-O-[6-O-(α-l-rhamnopyranosyl)hexyl] ester (6) was preliminarily evaluated against HL-60 human promyelocytic leukemia cells. The natural saponin 3 and designed saponin 4 exhibited comparable moderate cytotoxic activity under our testing conditions.     

Isolation of chromosaponin I-specific antibody by affinity chromatography

Chromosaponin I (CSI), a gamma-pyronyl-triterpenoid saponin isolated from pea and other leguminous plants, modulates several developmental processes of plant roots and activates the sugar taste receptor cells in blowflies. CSI is a unique saponin for its reducing power and biological activities in both plants and insects. In the present paper, we described the method of preparation for CSI-specific antibody using CSI-affinity and soyasaponin I-affinity columns. The antibody's-specific binding activity to CSI was confirmed by a bioassay using Arabidopsis roots and a ligand-molecule interaction analysis using BIAcore 3000. Because of the lability of CSI, the CSI-affinity column was made only by a moderate reaction condition in which CSI was coupled to EAH Sepharose 4B in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). The special control of the reaction temperature was essential to complete the coupling reaction; the reaction with EDC at 0 degrees C followed by a gradual increase in temperature.     

Probing cytoskeleton modulation by optical biosensors

This paper reported the use of resonant waveguide grating biosensors for studying the cytoskeleton structure in cells. This was achieved by measuring the changes in mass within the bottom portion of cells upon exposure to saponin in the absence and presence of cytoskeleton modulators. Treatment of Chinese hamster ovary cells with saponin led to a dose-dependent and dynamic mass changes. When a higher concentration of saponin (> 60 microg/ml) was used, a net loss in mass was observed. This is probably resulted from the diffusion of soluble intracellular materials away from the bottom portion of cells after pore formation in the cell plasma membranes by saponin. The pretreatment of cells with actin disruption agents, cytochalasin B and latrunculin A, led to significantly increased loss in cell mass induced by either 75 or 125 microg/ml saponin. These results suggested that optical biosensors provide an attractive means to study the cytoskeleton structure and screen modulators that affect the cytoskeleton structure.     

Synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue

The focus of this work was on the synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue. Therefore, 3-O-{[beta-D-glucopyranosyl-(1-->2)]-[alpha-L-arabinopyranosyl-(1-->3)]-alpha-L-arabinopyranosyl}ursolic acid-28-O-[beta-D-glucopyranosyl] ester 1 was concisely synthesized by two strategies in 22% and 41% overall yield, respectively, and another congener 3-O-{[beta-D-xylopyranosyl-(1-->2)]-[beta-D-glucopyranosyl-(1-->3)]-alpha-L-arabinopyranosyl}ursolic acid-28-O-[beta-D-glucopyranosyl] ester 2 was also efficiently prepared in 81% overall yield. The (1)H NMR and (13)C NMR signals of saponin 2 are all consistent with those reported for the natural product.