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At least 451 records · Page 25Linked to original sources
PubMed1990

A distinct characteristic of the quiescent state of human dermal fibroblasts in contracted collagen gel as revealed by no response to epidermal growth factor alone, but a positive growth response to a combination of the growth factor and saikosaponin b1.

It is known that fibroblasts cultured in a reconstituted collagen gel contract the gel, resulting in a high density of collagen fibrils comparable to that in dermis. Our previous study indicated that human fibroblasts in the contracted collagen gel did not proliferate in the presence of 10% serum even though there was no apparent cell-cell contact. We interpreted this cell growth inhibition as being caused by a high level of cell-collagen fibril interactions or cell-matrix contact inhibition. In the present study, the effect of epidermal growth factor (EGF) on fibroblast proliferation in the contracted collagen gel was compared with that on cells in other quiescent states. Non-dividing cells at confluency on a plastic dish or on collagen gel responded to the added EGF and multiplied, while the cells in the contracted collagen gel did not show any growth response to EGF at concentrations up to 100 ng/ml. Binding assay of [125I]-EGF to the cells showed that the number of binding sites and the binding constant obtained from Scatchard analysis were essentially unchanged in the contracted collagen gel, indicating that EGF receptors were not masked by collagen fibrils but that the signal transduction after binding of EGF was blocked. The block in the signal transduction was suppressed by the addition of saikosaponin b1. These results suggested that the quiescent fibroblasts in the contracted collagen gel were in a distinct state from previously known quiescent states of cultured cells, namely quiescent states due to cell-cell contact inhibition at confluency or to deficiency of growth factors. The mechanism of the effect of saikosaponin b1, which has a potent saponin activity, is discussed.

Adult↗
PubMed2001

Effects of Quillaja saponins on growth, metabolism, egg production and muscle cholesterol in individually reared Nile tilapia (Oreochromis niloticus).

The effects of supplementation of a Quillaja saponin (QS) mixture in the diets of tilapia have been studied using a respirometer system that allowed feeding and continuous measurement of oxygen consumption of individual fish. Five fish each were given control diet (C group) and control diet supplemented with 150 mg kg(-1) (S150 group) or 300 mg kg(-1) (S300 group) QS. At the end of 14 weeks the weight gain of the S300 group was significantly higher than control (P<0.05) whereas that of the S150 group had an intermediate value. The S150 group had a higher growth rate (P=0.05) after the first 3 weeks of feeding with the experimental diets, compared to the other two groups. At the end of the experiment the S300 group had significantly higher (P<0.05) average values for energy retention, apparent lipid conversion, carcass fat, energy and significantly lower (P<0.05) average values for apparently unutilised energy and carcass ash content compared to the C group. The corresponding values of the S150 group were intermediate between the C and S300 groups. One out of two female fish in the S150 group and both female fish in the S300 group never produced eggs during the entire 14-week experimental period. Contrarily, all three female fish in the control group and one out of the two female fish in the S150 group regularly produced eggs, at a rate of approximately once in every 14 days. The muscle cholesterol level in the S300 group was significantly higher than that of the C group. Possible mechanisms of action of the dietary saponins are discussed.

Animals↗
PubMed2001

Altered immunomodulating and toxicological properties of degraded Quillaja saponaria Molina saponins.

Quillaja saponins are readily hydrolyzed under physiological conditions, yielding deacylated forms that are significantly less toxic than their precursors. Yet, deacylated saponins are unable to stimulate a strong primary immune response. Although deacylated saponins elicit a strong total IgG response, their capacity to stimulate a Thl type IgG isotype profile (i.e. high levels of IgG2a and IgG2b) has been significantly diminished. Instead, an IgG profile closer to that of a Th2 immune response is stimulated (i.e. high IgG1 levels). Deacylated saponins have also lost their capacity to elicit an effective T cell immunity, as shown by their stimulation of a marginal lymphoproliferative response and their inability to elicit the production of cytotoxic lymphocytes (CTL). Modification of the immune-modulating properties brought by the degradation of quillaja saponins during vaccine storage may change the intended immune response from a Th1 to a Th2 type. This alteration would have negligible effects on vaccines depending on Th2 immunity mediated by neutralizing antibodies. However, the performance of vaccines directed against intracellular pathogens as well as therapeutic cancer vaccines may be seriously affected by the loss of their capacity to stimulate both a Th1 immune response and the production of CTL.

Adjuvants, Immunologic↗
PubMed2006

Synthetic studies of complex immunostimulants from Quillaja saponaria: synthesis of the potent clinical immunoadjuvant QS-21Aapi.

QS-21 is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing vaccine therapy clinical trials involving QS-21 as a critical adjuvant component for immune response augmentation. QS-21 is a natural product immunostimulatory adjuvant, eliciting both T-cell- and antibody-mediated immune responses with microgram doses. Herein is reported the synthesis of QS-21A(api) in a highly modular strategy, applying novel glycosylation methodologies to a convergent construction of the potent saponin immunostimulant. The chemical synthesis of QS-21 offers unique opportunities to probe its mode of biological action through the preparation of otherwise unattainable nonnatural saponin analogues.

Adjuvants, Immunologic↗
PubMed2001

Regioselective enzymatic glycosylation of natural polyhydroxylated compounds: galactosylation and glucosylation of protopanaxatriol ginsenosides.

Ginsenoside Rg1 (1), the most representative Ginsenoside from Panax Ginseng C.A. Meyer belonging to the protopanaxatriol family, has been galactosylated by action of the beta-(1,4)-galactosyltransferase (GalT) from bovine colostrum, using UDP-galactose as an activated sugar donor. The enzyme showed the well-known specificity for the formation of a beta-linkage with the C-4 OH of the glucose acceptor, but it was not able to discriminate between the two glucose moieties of 1, giving a mixture of mono- and digalactosylated derivatives. Other natural Rg1-analogues such as F1, Rh1, Re, as well as the synthetic derivative 6'-O-acetyl-Rg1 have been also galactosylated, giving monolactosyl derivatives. GalT was also able to accept UDP-glucose as an activated sugar donor, giving rise to cellobiosyl derivatives of Rg1.

Carbohydrate Sequence↗
PubMed2001

Secondary metabolites from the roots of Astragalus zahlbruckneri.

Four new phenolic glycosides, beta-apiofuranosyl-(1-->2)-beta-glucopyranosides (1-4), along with the cycloartane triterpenes 20(R),25-epoxy-3beta,6alpha,16beta,24alpha-tetrahydroxycycloartane (5) and 20(R),24(S)-epoxy-3beta,6alpha,25-trihydroxycycloartan-16-one (6) were isolated from roots of Astragalus zahlbruckneri. The structure elucidation of all compounds was based on their (1)H and (13)C NMR spectral data including 1D-TOCSY, DQF-COSY, HSQC, and HMBC experiments.

Astragalus Plant↗
PubMed2005

Microbial transformation of 20(S)-protopanaxatriol by Mucor spinosus.

Microbial biotransformation of 20(S)-protopanaxatriol (1) by the fungus Mucor spinosus (AS 3.3450) yielded four new metabolites, the structures of which were determined to be 12-oxo-15alpha-hydroxyl-20(S)-protopanaxatriol (2), 27-hydroxyl-20(S)-protopanaxatriol (3), 12-oxo-26-hydroxyl-20(S)-protopanaxatriol (4), and 12-oxo-27-hydroxyl-20(S)-protopanaxatriol (5), respectively, on the basis of their chemical and spectroscopic data. All the new metabolites, as well as the substrate, had significant cytotoxic effects on HL-60 cells (human leukemia cells).

Antineoplastic Agents↗
PubMed1995

Anti-inflammatory activity of saikosaponins from Heteromorpha trifoliata.

By means of activity-directed chromatographic fractionation using the 12-O-tetradecanoylphorbol acetate (TPA)-induced edema test, two saikosaponins were isolated from the MeOH extract of Heteromorpha trifoliata leaves. They were identified as 16 beta, 23-dihydroxy-13,28-epoxyolean-11-en-3 beta-yl-[beta-D-glucopyranosyl (1-->2)]-[beta-D-glucopyranosyl (1-->3)]-beta-D-fucopyranoside [1] and 16 beta, 23,28-trihydroxy-11 alpha-methoxyolean-12-en-3 beta-yl-[beta-D-glucopyranosyl (1-->2)]-[beta-D-glucopyranosyl (1-->3) [beta-D-fucopyranoside [2]. Compound 1 showed activity in the TPA and ethylphenylpropiolate (EPP) mouse ear edema and the serotonin paw edema tests, whereas compound 2 was active only in the mouse ear edema model. Both substances had only a slight effect against a carrageenan paw edema model. The anti-inflammatory action of compound 1 was notably decreased by the mRNA and protein synthesis inhibitors actinomycin D and cycloheximide.

Animals↗
PubMed2003

Polyphosphoric acid trimethylsilyl ester promoted intramolecular acylation of an olefin by a carboxylic acid: convenient construction of C-18-functionalized delta14-hecogenin acetate.

[reaction: see text]. Polyphosphoric acid trimethylsilyl ester (PPSE)-promoted intramolecular Friedel-Crafts reactions on a nonaromatic carboxylic acid system have been investigated. Studies led to the synthesis of C-18 functionalized steroidal compounds 5 and 9a-d with strict retention of the spiroketals. Isomerization of spiroketal 9e was studied.

Acylation↗
PubMed2000

Effect of saikosaponin, a triterpene saponin, on apoptosis in lymphocytes: association with c-myc, p53, and bcl-2 mRNA.

1. The mechanisms involved in the apoptotic effect of saikosaponin-d, a triterpene saponin from Bupleurum falcatum L., were studied in human CEM lymphocytes and compared with those of dexamethasone (3 x 10(-7) M). 2. Saikosaponin-d (10(-8) to 10(-5) M) inhibited the serum-stimulated [(3)H]-thymidine incorporation in a concentration-dependent manner. Dexamethasone also inhibited serum-stimulated [(3)H]-thymidine incorporation. 3. Cell viability was unaffected by saikosaponin-d until 10(-5) - 10(-4) M. Dexamethasone significantly reduced the number of viable cells. 4. Following saikosaponin-d (10(-5) - 10(-4) M) treatment, flow cytometry analysis of propidium iodide-stained cells showed a significant increase in the percentage of cells in the apoptotic region. Dexamethasone also significantly increased the percentage of apoptotic cells. The supravital exposure to propidium iodide and annexin V labelling demonstrated that saikosaponin-d (10(-5) - 10(-4) M) induced apoptosis as well as necrosis. 5. The apoptotic effect of saikosaponin-d (3 x 10(-6) - 10(-4) M) was also demonstrated by TUNEL analysis and DNA laddering. The percentage of apoptotic cells induced by saikosaponin-d (3 x 10(-6) - 10(-5) M) was unaffected by the presence of Z-VAD-FMK, indicating that saikosaponin-d-induced apoptosis may not be mediated by caspase activity. However, the percentage of apoptotic cells induced by dexamethasone was significantly reduced by the presence of Z-VAD-FMK. 6. Levels of c-myc, p53, and bcl-2 mRNA were analysed by the reverse transcription-polymerase chain reaction. Levels of c-myc and p53 mRNA were significantly increased, while the level of bcl-2 mRNA was decreased, by saikosaponin-d (10(-5) M) treatment. Dexamethasone did not significantly change the expression of these genes. 7. It is suggested that the apoptotic effect of saikosaponin-d may be partly mediated by increases in c-myc and p53 mRNA levels accompanied by a decrease in bcl-2 mRNA level.

Amino Acid Chloromethyl Ketones↗
PubMed2004

Abeta(25-35)-induced memory impairment, axonal atrophy, and synaptic loss are ameliorated by M1, A metabolite of protopanaxadiol-type saponins.

We previously screened neurite outgrowth activities of several Ginseng drugs in human neuroblastoma, and demonstrated that protopanaxadiol (ppd)-type saponins were active constituents. Since ppd-type saponins are known to be completely metabolized to 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1) by intestinal bacteria when taken orally, M1 and ginsenoside Rb1, as a representative of ppd-type saponins, were examined for cognitive disorder. In a mouse model of Alzheimer's disease (AD) by Abeta(25-35) i.c.v. injection, impaired spatial memory was recovered by p.o. administration of ginsenoside Rb1 or M1. Although the expression levels of phosphorylated NF-H and synaptophysin were reduced in the cerebral cortex and the hippocampus of Abeta(25-35)-injected mice, their levels in ginsenoside Rb1- and M1-treated mice were almost completely recovered up to control levels. Potencies of the effects were not different between ginsenoside Rb1 and M1 when given orally, suggesting that most of the ginsenoside Rb1 may be metabolized to M1, and M1 is an active principal of ppd-type saponins for the memory improvement. In cultured rat cortical neurons, M1 showed extension activity of axons, but not dendrites. The axon-specific outgrowth was seen even when neuritic atrophy had already progressed in response to administration of Abeta(25-35) as well as in the normal condition. These results suggest that M1 has axonal extension activity in degenerated neurons, and improve memory disorder and synaptic loss induced by Abeta(25-35). M1 was shown to be effective in vitro and in vivo, indicating that Ginseng drugs containing ppd-type saponins may reactivate neuronal function in AD by p.o. administration.

Amyloid beta-Peptides↗
PubMed2006

Metabolite 1 of protopanaxadiol-type saponins, an axonal regenerative factor, stimulates teneurin-2 linked by PI3-kinase cascade.

We previously showed that 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1), a metabolite of protopanaxadiol-type ginseng saponins by intestinal bacteria had axonal extension activity in degenerated neurons, and improved memory disorder and synaptic loss induced by an active fragment of amyloid beta, Abeta(25-35). It is unknown how M1 shows these effects in neurons. To clarify the signal transduction mechanism of M1-induced axonal extension, phosphorylated proteins by M1 stimulation were identified because most cellular signal pathways are regulated by phosphorylation/dephosphorylation. The combination of immunoprecipitation and MALDI-TOF-MS revealed that teneurin-2 and mPar3 were specifically phosphorylated by M1 stimulation. Because mPar3 is known as an axonal specifying molecule and to be regulated by phosphatidylinositol 3-kinase (PI3-kinase), the involvement of teneurin-2 and PI3-kinase in the M1 signal was studied. In teneurin-2-deficient cortical neurons, M1-induced axonal extension and PI3-kinase activation were significantly inhibited. In addition, treatment with PI3-kinase inhibitor also reduced M1-induced axonal extension. These results suggest that M1 induces axonal outgrowth through the teneurin-2-PI3-kinase cascade.

Amyloid beta-Peptides↗
PubMed1997

Influence of Quillaja saponaria triterpenoid content on the immunomodulatory capacity of Epstein-Barr virus iscoms.

The immune responses to immunostimulating complexes (iscoms) containing recombinant Epstein-Barr virus (EBV) gp340 envelope protein was evaluated in BALB/c (H-2(d)) and CBA (H-2(k)) mice. Gp340-iscoms were used either with a low content of Quillaja triterpenoid adjuvant (L-iscoms) or supplemented with additional Quillaja adjuvant in the form of iscomatrix (S-iscoms). Class and subclass distribution of anti-gp340 antibodies, EBV-neutralizing antibodies, antigen-specific T cell proliferation and cytokine production were determined and these results compared to those obtained by immunization with non-adjuvated gp340. The H-2(d) and H-2(k) mice were characterized as low or high responders in respect to the level of specific anti-gp340 antibodies, secretion of IgG2a isotype, antigen-specific lymphoproliferative capacity, interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) production in the basic immunizations with gp340. While presentation of the antigen in iscom formulations with low levels of Quillaja triterpenoids induces a moderate enhancement of the immune responses in the low responder H-2(d) mice, supplementation with high levels of iscomatrix immunomodulator was required to enhance the immune responses in the high responder H-2(k) mice. In both mouse strains subcutaneous immunization with S-iscoms resulted in a significant increase of IgG1- and IgG2a-specific antibodies, as well as in strong antigen-specific proliferative response confirmed by the simultaneous cytokine production. The enhanced antigen-specific secretion of IL-2 and IFN-gamma together with the abrogation of IL-10 and the absence of IL-4 indicates that the responses were driven towards a Th1-type rather than Th2-type immune response. The S-iscom formulations minimized the differences in immune responses between the two mouse strains, but the capacity of immune sera to neutralize EBV transformation in vitro remained completely strain-dependent. These data indicate that immune responses generated by iscoms can be manipulated by altering the triterpenoid composition of the iscoms and that the levels of triterpenoids can determine whether or not a Th1-type response is made.

Adjuvants, Immunologic↗