Triterpenoid Aglycones Research Articles

Neuroprotection by saponins.

Saponins, an important group of bioactive plant natural products, are glycosides of triterpenoid or steroidal aglycones. Their diverse biological activities are ascribed to their different structures. Saponins have long been recognized as key ingredients in traditional Chinese medicine. Accumulated evidence suggests that saponins have significant neuroprotective effects on attenuation of central nervous system disorders, such as stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, our understanding of the mechanisms underlying the observed effects remains incomplete. Based on recently reported data from basic and clinical studies, this review highlights the proposed mechanisms of their neuroprotective function including antioxidant, modulation of neurotransmitters, anti-apoptosis, anti-inflammation, attenuating Ca(2+) influx, modulating neurotrophic factors, inhibiting tau phosphorylation, and regeneration of neural networks.

Platycosides from the Roots of Platycodon grandiflorum and Their Health Benefits.

The extracts and pure saponins from the roots of Platycodon grandiflorum (PG) are reported to have a wide range of health benefits. Platycosides (saponins) from the roots of PG are characterized by a structure containing a triterpenoid aglycone and two sugar chains. Saponins are of commercial significance, and their applications are increasing with increasing evidence of their health benefits. The biological effects of saponins include cytotoxic effects against cancer cells, neuroprotective activity, antiviral activity, and cholesterol lowering effects. Saponins with commercial value range from crude plant extracts, which can be used for their foaming properties, to high purity saponins such as platycodin D, which can be used for its health applications (e.g., as a vaccine adjuvant). This review reveals that platycosides have many health benefits and have the potential to be used as a remedy against many of the major health hazards (e.g., cancer, obesity, alzheimer’s) faced by populations around the world. Methods of platycoside purification and analysis are also covered in this review.

Isolation and Structural Determination of Triterpenoid Glycosides from the Aerial Parts of Alsike Clover (Trifolium hybridum L.)

Five azukisapogenol glycosides (1-5) have been isolated from the aerial parts of alsike clover (Trifolium hybridum L.), and their structures were elucidated by combined spectroscopic, spectrometric (1D and 2D NMR; HRESIMS, ESI-MS/MS), and chemical methods. Three of them are new compounds and were identified as 3-O-[-α-L-arabinopyranosyl(1→2)]-β-D-glucuronopyranosyl azukisapogenol (1), 3-O-[-β-D-glucuronopyranosyl(1→2)-β-D-glucuronopyranosyl]-29-O-β-D-glucopyranosyl azukisapogenol (2), and 3-O-[-α-L-arabinopyranosyl(1→2)-β-D-glucuronopyranosyl]-29-O-β-D-glucopyranosyl azukisapogenol (3). The remaining two (4, 5) are known compounds but have not been previously described as saponins constituents of the genus Trifolium . Also, azukisapogenol is reported here as a triterpenoid aglycone for the first time in this genus. Finally, the main chemotaxonomic features that may be recognized as specific of Trifolium species were discussed.

Identification of metabolic profiling of cell culture of licorice compared with its native one

Glycyrrhiza uralensis has long been used as a flavoring and sweetening agent in food products. In the last ten years, suspensions of Glycyrhiza cells have been successfully established. However, there is no report of full metabolic profiling research on these cells. To identify their composition we used HPLC-DAD coupled with ESI(+/-)-MS (n) to compare the constituents of cultured Glycyrhiza (CG) cells with those the native cells (NG). We identified 60 compounds including flavonoids, phenols, and triterpenoids. Among these compounds, 42 occurred both in NG and CG, nine were present in NG only and nine were present in CG alone. The number of the triterpenoid aglycones without glycones in CG was smaller than that in NG. The number of flavanone, isoflavone, isoflavan, and benzenoid compounds was also smaller in CG than that in NG, whereas the number of pterocarpans was much higher. Although differences existed between CG and NG, the extract of CG was similar to that of NG. With the development of cell suspension culture-based biotransformation, cell culture of Glycyrrhiza has the potential to be more profitable than field cultivation in some areas.

Characterization and quantification of the triterpenoids in different parts of Xanthoceras sorbifolia by HPLC–ESI-MS

Two new triterpenoid glycosides, sorbifoside A ( 2) and B ( 3), were isolated from the husks of Xanthoceras sorbifolia along with two known saponins ( 1, 5). Their structures were established on the basis of 1D and 2D NMR data. A simple and sensitive assay was developed for the simultaneous determination of 6 triterpenoids ( 1– 6, including two triterpenoid aglycones) in X. sorbifolia based on high performance liquid chromatography–mass spectrometry (HPLC–MS) coupled to an electrospray ionization (ESI) interface. The analytes were detected by positive ESI ionization mode and quantified by selected ion monitoring (SIM). All the linear regressions were acquired with r 2 > 0.998. The precisions were evaluated by intra- and inter-day tests, and the relative standard deviation (RSD) values were within the range of 2.0–2.8% and 1.7–2.9%, respectively. The recoveries for the quantified compounds were observed over the range of 95.3–104.7% with RSD values less than 4.6%. The method developed was successfully applied for simultaneous quantification of the six triterpenoids in X. sorbifolia, and our results showed that the contents of triterpenoids in different parts of X. sorbifolia varied significantly.

Cytotoxic Triterpenoid Saponins Acetylated with Monoterpenoid Acid from Albizia julibrissin

AbstractThree new triterpenoid saponins, named julibroside J16 (2), julibroside J17 (3), and julibroside J21 (4), each of which possesses an oleanane triterpenoid aglycone of acacic acid, two monoterpenoid acids, and nine sugar moieties, together with one known saponin, julibroside II (1), were isolated from the stem bark of Albizia julibrissin by chromatographic methods. Their structures were established by chemical and spectroscopic means. Saponins 1, 2, and 4 showed inhibitory activities against Bel 7402 human cancer cell line in vitro.

Cloning and Characterization of Oxidosqualene Cyclases from Kalanchoe daigremontiana: ENZYMES CATALYZING UP TO 10 REARRANGEMENT STEPS YIELDING FRIEDELIN AND OTHER TRITERPENOIDS

The first committed step in triterpenoid biosynthesis is the cyclization of oxidosqualene to polycyclic alcohols or ketones C(30)H(50)O. It is catalyzed by single oxidosqualene cyclase (OSC) enzymes that can carry out varying numbers of carbocation rearrangements and, thus, generate triterpenoids with diverse carbon skeletons. OSCs from diverse plant species have been cloned and characterized, the large majority of them catalyzing relatively few rearrangement steps. It was recently predicted that special OSCs must exist that can form friedelin, the pentacyclic triterpenoid whose formation involves the maximum possible number of rearrangement steps. The goal of the present study, therefore, was to clone a friedelin synthase from Kalanchoe daigremontiana, a plant species known to accumulate this triterpenoid in its leaf surface waxes. Five OSC cDNAs were isolated, encoding proteins with 761-779 amino acids and sharing between 57.4 and 94.3% nucleotide sequence identity. Heterologous expression in yeast and GC-MS analyses showed that one of the OSCs generated the steroid cycloartenol together with minor side products, whereas the other four enzymes produced mixtures of pentacyclic triterpenoids dominated by lupeol (93%), taraxerol (60%), glutinol (66%), and friedelin (71%), respectively. The cycloartenol synthase was found expressed in all leaf tissues, whereas the lupeol, taraxerol, glutinol, and friedelin synthases were expressed only in the epidermis layers lining the upper and lower surfaces of the leaf blade. It is concluded that the function of these enzymes is to form respective triterpenoid aglycones destined to coat the leaf exterior, probably as defense compounds against pathogens or herbivores.

Abstract 5624: Saponins from Gypsophila paniculata L significantly potentiate the immunospecific cytotoxic activity of anti-CD19 and CD38 saporin-based immunotoxins for a human lymphoma cell line

Abstract Saponins are a highly diverse group of glycosides of plant origin containing either a steroidal or triterpenoid aglycone to which one or more sugar chains are attached. They have been variously described as enhancing the cytotoxic activity of ribosome-inactivating proteins (RIPs) and ligand-directing conjugates constructed with these for eukaryotic cells. Saponins are thought to facilitate the entry of RIPs into the cytosol across the membranes of intracellular vesicular structures. This characteristic of saponins therefore makes them of interest as molecules that could be useful in improving the therapeutic index of immunotoxins (IT) in a clinical setting. In the current study we used a protein synthesis inhibition assay based on leucine incorporation together with cell proliferation studies in culture to demonstrate that saponins from Gypsophila paniculata L. potentiate the cytotoxicity of the anti-CD19 and CD38 saporin-based immunotoxins (BU12-SAPORIN and OKT10-SAPORIN, respectively) by several thousand-fold for the human lymphoma cell line Daudi. Various experiments revealed that the enhancing effect of saponins on immunotoxin activity did not appear to be dependent on extra cellular pH in the assay system we used. Kinetic studies further revealed that saponin at a predetermined optimal concentration of 2 μg/ml reduced the t10 (time taken to reduce protein synthesis to 10% of the level seen in control Daudi cells) for OKT10-SAPORIN at 0.1μg/ml from 50 hours without saponin to 12.5 hours with saponin. In blocking experiments using OKT10-SAPORIN IT at the IC50 concentration in combination with saponin together with a gross excess of native OKT10 antibody we established that the immunospecific cytotoxic activity of OKT10-SAPORIN was fully retained when leucine incorporation was used as the surrogate measure of cytotoxicity but only partially so when thymidine incorporation was used. This observation of a partial uncoupling of protein and DNA synthesis as a measure of cytotoxicity was further supported by cell proliferation experiments in culture which were undertaken in parallel. If saponins are to be of any clinical value as candidate molecules for improving the therapeutic index of immunotoxins it is imperative that the immunospecificity of IT activity is fully retained. Whilst this study clearly demonstrates that saponins from G. paniculata L. do indeed significantly potentiate IT activity it seems that this effect may only be partially immunospecific. Nevertheless, the dramatic improvements that saponins confer on IT activity argue in favor of in vivo experiments in transgenic animal models of human lymphoma combined with additional studies to explore other strategies that might be employed to improve the immunospecific effect achievable. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5624.

Genomic and coexpression analyses predict multiple genes involved in triterpene saponin biosynthesis in Medicago truncatula.

Saponins, an important group of bioactive plant natural products, are glycosides of triterpenoid or steroidal aglycones (sapogenins). Saponins possess many biological activities, including conferring potential health benefits for humans. However, most of the steps specific for the biosynthesis of triterpene saponins remain uncharacterized at the molecular level. Here, we use comprehensive gene expression clustering analysis to identify candidate genes involved in the elaboration, hydroxylation, and glycosylation of the triterpene skeleton in the model legume Medicago truncatula. Four candidate uridine diphosphate glycosyltransferases were expressed in Escherichia coli, one of which (UGT73F3) showed specificity for multiple sapogenins and was confirmed to glucosylate hederagenin at the C28 position. Genetic loss-of-function studies in M. truncatula confirmed the in vivo function of UGT73F3 in saponin biosynthesis. This report provides a basis for future studies to define genetically the roles of multiple cytochromes P450 and glycosyltransferases in triterpene saponin biosynthesis in Medicago.

Studies on protein characteristics and toxic constituents of Simarouba glauca oilseed meal

In order to exploit the protein rich (47.7g/100g) simarouba meal in food/feed, studies were conducted on its chemical composition with emphasis on protein characteristics and toxic constituents. Simarouba meal contained high calcium (143mg/100g) and sodium (79mg/100g). Saponins with triterpenoid aglycone (3.7g/100g), alkaloids (1.01g/100g), phenolics (0.95g/100g) and phytic acid (0.73g/100g) were the major toxic constituents identified in simarouba meal. TLC and HPLC results indicated that among different fractions of simarouba saponins, one dominant fraction accounted for about 28%. Proteins of simarouba recorded high in vitro digestibility (88%). SDS–PAGE revealed four major protein bands in molecular weight ranges of 20–24, 36–45 and 55–66kDa. Apart from, glutamic acid (23.43g/100g protein) and arginine (10.75g/100g protein), simarouba protein contained high essential amino acids like leucine (7.76g/100g protein), lysine (5.62g/100g protein) and valine (6.12g/100g protein). Among nutritional indices, simarouba meal recorded a good EAA Index (75.02), C-PER (1.90) and PDCAAS (1.0-Adult group).

Saponins as Tool for Improved Targeted Tumor Therapies

Saponins are plant glycosides that consist of a steroid, steroid alkaloid or triterpenoid aglycone and one or more sugar chains that are covalently linked by glycosidic binding to the aglycone. Glucose, galactose, glucuronic acid, xylose and rhamnose are commonly bound monosaccharides. Saponins are found in all organs of a variety of higher plants. Due to the great variability of their structures, diverse functions have been described for distinct saponins; including foaming and pore forming properties as well as selective removal of protozoa from the rumen. The most interesting properties are, however, favorable anti-tumorigenic effects. Several saponins inhibit tumor cell growth by cell cycle arrest and apoptosis with half maximal inhibitory concentrations of down to 0.2 microM. A drawback of saponins in tumor therapy is the non-targeted spreading throughout the whole body. Surprisingly, certain saponins were identified that drastically enhance the efficacy of targeted chimeric toxins bearing the ribosome-inactivating protein saporin as cell-killing moiety. It was demonstrated that this effect is substantially more pronounced on target cells than on non-target cells, thus not only preserving the target specificity of the chimeric toxin but also broadening the therapeutic window with simultaneous dose lowering. This review describes the role of saponins as drug in general, their use as single drug treatment in tumor therapy, their combination with conventional tumor treatment strategies and the synergistic effects with particular targeted tumor therapies that are based on recombinant proteins.

Protection Against Selenite Cataract in Rat Lens by Drevogenin D, a Triterpenoid Aglycone fromDregea volubilis

Dregea volubilis is a woody climbing plant commonly found in the hotter parts of India. The leaves are edible and used as a green vegetable, while the plant extract has been used traditionally to treat several diseases including eye ailments. Drevogenin D is a triterpenoid aglycone that has been isolated, purified, and characterized as an active component from the leaves of D. volubilis. In this study, drevogenin D was evaluated for antioxidant and potential anticataractogenic activity in an in vitro model. 1,1-Diphenyl-2-picrylhydrazyl radical and superoxide radical scavenging activities of drevogenin D were studied and found to exhibit a 50% inhibitory concentration of 43 microg/mL and 200.6 microg/mL, respectively. Normal rat lenses cultured in 0.1 mM sodium selenite-supplemented medium were used as the experimental model for this study. Selenite-induced models are excellent mimics of oxidative stress induced cataract. Treatment with drevogenin D at a concentration of 50 microg/mL medium was found to reverse the level of activity of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, elevate the level of reduced glutathione and protein sulfhydryl, and lower the level of lipid peroxidation as indicated by the concentration of thiobarbituric acid-reacting substances. These results indicate good antioxidant activity and potential anticataractogenic activity for drevogenin D against selenite-induced cataractous changes, which have been reported for the first time.

The antioxidant activities of natural sweeteners, mogrosides, from fruits of Siraitia grosvenori

To search for antioxidant agents from natural resources, in this paper the in vitro antioxidant activities of two natural sweeteners, mogroside V and 11-oxo-mogroside V isolated from the fruits of Siraitia grosvenori, were determined using chemiluminescence (CL). The results showed that these sweet glycosides, having cucurbitane triterpenoid aglycon, exhibited significant inhibitory effects on reactive oxygen species (, H2O2 and •OH) and DNA oxidative damage. 11-oxo-mogroside V showed a higher scavenging effect on (concentration at which 50% of chemiluminescence intensity is inhibited [EC50]=4.79 µg/ml) and H2O2 (EC50=16.52 µg/ml) than those of mogroside V. However, mogroside V was more effective in scavenging •OH, with EC50=48.44 µg/ml compared with that of 11-oxo-mogroside V (EC50=146.17 µg/ml). Further, 11-oxo-mogroside V exhibited a remarkable inhibitory effect on •OH-induced DNA damage with EC50=3.09 µg/ml.

The Saponin-Mediated Enhanced Uptake of Targeted Saporin-Based Drugs is Strongly Dependent on the Saponin Structure

Saponins are a group of plant glycosides consisting of a steroid or triterpenoid aglycone to which one or more sugar chains are attached. They exhibit cell membrane-permeabilizing properties and, thus, have been investigated for their therapeutic potential. Recently, at a non-permeabilizing concentration saponinum album from Gypsophila paniculata L. has been described to enhance the cytotoxicity of a chimeric toxin in a cell culture model. To elucidate whether this enhancing effect is also mediated by other saponins, we analyzed the ability of seven different saponins to enhance the cytotoxicity of a targeted chimeric toxin. The chimeric toxin is composed of saporin, a plant ribosome-inactivating toxin, a cleavable adapter, and human epidermal growth factor (EGF). Cytotoxicity on EGF receptor (EGFR)-bearing cells was analyzed both alone and after combined application of saponin and chimeric toxin. Only two of the tested saponins, quillajasaponin and saponinum album, enhanced cytotoxicity by more than 1,000-fold, whereas the enhancement factors of the other saponins were only approximately 10-fold. In contrast to saponinum album, quillajasaponin enhanced the cytotoxicity both on control cells lacking EGFR and on target cells, indicating that, in this case, the enhancement is not target cell receptor specific. This is also the case for some of the saponins with low enhancement factors. Saponinum album resulted in a more than 13,600-fold receptor-specific enhancement, decreasing the 50% inhibitory concentration (IC(50)) from 2.4 nM to 0.18 pM, which renders it the best option to promote saporin-3-based drug uptake while retaining specificity for the EGFR.

Philinopgenin A, B, and C, Three New Triterpenoid Aglycones from the Sea Cucumber Pentacta quadrangulasis

Three new triterpenoid aglycones named Philinopgenin A (1), B (2), and C (3) were isolated from the acid hydrolysate of the crude glycoside mixture prepared from the whole sea cucumber Pentacta quadrangulasis Lesson. The corresponding structures were determined as 16β-acetoxyholosta-8(9), 24(25)-diene-3β-ol (1), 20, 25-epoxy-lanosta-9(11)-ene-3β-ol 18(16)–lactone (2) and 16β-acetoxyholosta-9(11), 24(25)-diene-3β-ol (3), respectively, on the basis of spectral evidence.

Anticarcinogenic activity of natural sweeteners, cucurbitane glycosides, from Momordica grosvenori.

To search for cancer chemopreventive agents from natural resources, many phytochemicals and food additives have been screened. Consequently, two natural sweeteners, mogroside V and 11-oxo-mogroside V isolated from the fruits of Momordica grosvenori, exhibited strong inhibitory effect on the primary screening test indicated by the induction of Epstein-Barr virus early antigen (EBV-EA) by a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). These sweet glycosides, having cucurbitane triterpenoid aglycon, exhibited the significant inhibitory effects on the two-stage carcinogenesis test of mouse skin tumors induced by peroxynitrite (ONOO-) as an initiator and TPA as a promoter. Further, 11-oxo-mogroside V also exhibited the remarkable inhibitory effect on two-stage carcinogenesis test of mouse skin tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter.

Isolation and structure elucidation of four new triterpenoid estersaponins from fruits of Pittosporum tobiraait.

Four new triterpenoid estersaponins, tentatively designated as IIIA 2 ( 1 ), IIIA 3 ( 2 ), IIIB 2 ( 3 ), and IIIC 4 ( 4 ) have been isolated from fruits of Pittosporum tobira ait. and their structures elucidated by spectroscopic and chemical analyses. All the four compounds consist of an acylated pentacyclic triterpenoid aglycone which bears the same oligosaccharide portion. The crude saponin mixture (CIDI) was found to show significant in vitro and in vivo cytotoxicity in different human cancer cell lines.

Triterpenoid glycosides of Scheffleropsis angkae. III. Structure of glycoside L-I1.

A new triterpenoid glycoside L-I1, the 28-O-α-L-rhamnopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester of 3β,23,27-trihydroxylup-20(29)-en-28-oic acid, is isolated from the leaves ofScheffleropsis angkae(Araliaceae). Its structure is established by chemical methods and various NMR techniques (1H,13C, APT, COSY, TOCSY, ROESY, HSQC, HMBC). 3β,23,27-Trihydroxylup-20(29)-en-28-oic acid is a new triterpenoid aglycone

Studies on bioactive saponins from Chinese medicinal plants.

In our recent studies on bioactive saponins, two Chinese medicinal plants: Mussaenda pubescens Ait.f (Rubiaceae) and Clematis chinensis Osbeck (Ranunculaceae), were investigated. Of the two medicinal plants, M. pubescens is a Chinese folk medicine which has been used as a diuretic, antiphlogistic, diaphoretic and antipyretic agent, and has also been used to detoxify mushroom poisons and to terminate early pregnancy. Clematis chinensis is a Chinese traditional medicine which has been used as an analgesic, diuretic, antitumor, antiinflammatory and insecticidal agent for ages. As a result of our studies, eighteen saponins were identified from M. pubescens, among which seventeen were new compounds, while eleven saponins were isolated from C. chinensis, three of which were new compounds. In the course of our structural studies, mass fragment analysis in FAB-mass spectra and 1H- and 13C-NMR spectra were used to determine the structures of the sapogenin and oligosaccharide moieties. In those more complicated and minor saponins, various 2D-NMR experiments were carried out on 400-, 500- or 600-MHz NMR instruments, which permitted the identification of new sapogenins in glycoside form. In addition, it was also possible to assign all the proton and carbon signals of the sugar units on the basis of 1H-1H DQF COSY, TOCSY and HMQC spectra, which further permitted the establishment of linkage sites and sequences among the sugar units and aglycones by means of NOESY, ROESY and HMBC spectra. When the proton signals of sugar units are overlapped seriously in 1H-NMR spectra, peracetylation is a very helpful technique which can spread proton signals in wider range, thus simplifying their assignment by means of 2D-NMR spectra. When some of the sugar proton signals of a peracetylate are also overlapped coincidentally, alternation of deuterated solvents for measuring NMR spectra can circumvent the difficulties. Pharmacological tests indicated that mussaendoside O, the most abundant saponin from M. pubescens, can inhibit significantly the secretions of the lachrymal and salivary glands induced by galanthamine, and can also inhibit the contraction of the isolated longitudinal muscle strip from guinea pig ileum evoked by an M-Ach receptor agonist (carbachol, 10(-6) M) at concentrations of 10(-4) and 10(-5) M. From these results, the saponin should be an antagonist of the M-Ach receptor, and was presumed to be responsible for its antitoxicity activity toward some mushroom poisons of medicinal plant origin. In addition, mussaendoside O also showed immunopromotive and hemolytic activities.

Mabioside B, A Novel Saponin fromColubrina Elliptica

Abstract One novel saponin, mabioside B (1), containing a seco ring D dammarane triterpenoid aglycone has been isolated from the bark of Colubrina elliptica. The structure was established by spectroscopic methods.