Triterpenoid saponins from Clematis tangutica

Anticancer properties and mechanism insights of α-hederin

α-Hederin is a natural bioactive molecule very abundant in aromatic and medicinal plants (AMP). It was identified, characterized, and isolated using different extraction and characterization technologies, such as HPLC, LC-MS and NMR. Biological tests have revealed that this natural molecule possesses different biological properties, particularly anticancer activity. Indeed, this activity has been investigated against several cancers (e.g., esophageal, hepatic, breast, colon, colorectal, lung, ovarian, and gastric). The underlying mechanisms are varied and include induction of apoptosis and cell cycle arrest, reduction of ATP generation, as well as inhibition of autophagy, cell proliferation, invasion, and metastasis. In fact, these anticancer mechanisms are considered the most targeted for new chemotherapeutic agents' development. In the light of all these data, α-hederin could be a very interesting candidate as an anticancer drug for chemotherapy, as well as it could be used in combination with other molecules already validated or possibly investigated as an agent sensitizing tumor cells to chemotherapeutic treatments.

Separation of a new triterpenoid saponin together with six known ones from Clematis tangutica (Maxim.) Korsh and evaluation of their cytotoxic activities

A new triterpenoid saponin, 3-O-β-D-allopyranosyl (1→3)-α-L-rhamnopyranosyl (1→2)-α-L-arabinopyranosyl hederagenin 28-O-α-L-rhamnopyranosyl (1→4)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl ester (IV), together with six known ones Hederacholichiside F (I), Tanguticoside B (II), Tauroside St-H₁ (III), Hederoside H₁ (V), Kalopanaxsaponin G (VI), Hederasaponin B (VII) were separated from Clematis tangutica (Maxim.) Korsh. Their cytotoxic activities were evaluated. Saponins IV (new compound) and I showed selective inhibitory activities against HGC-27 with IC₅₀ values of 20.17 and 66.18 μM. Saponin VII exhibited extensive inhibitory action against HGC-27, Hela and SK-OV-3 with IC₅₀ values of 16.47-71.36 μM. Saponin III showed selective inhibitory activity against SK-OV-3 with the IC₅₀ value of 48.70 μM. All isolated saponins were inactive (IC₅₀ >150 μM) to GES-1.

Triterpenoid Saponins From the Fruit of Acanthopanax senticosus (Rupr. & Maxim.) Harms

Five new oleanane-type triterpenoid saponins (1–5), together with 24 known saponins (6–29) were isolated from the fruit of Acanthopanax senticosus. Their structures were determined by extensive spectroscopic analysis, including 1D, 2D nuclear magnetic resonance (NMR), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), in combination with chemical methods (acid hydrolysis). The neuroinflammation model was established by lipopolysaccharide (LPS)-induced BV2 microglia, and the neuroprotective effects of all compounds (1–29) were evaluated.

Manniosides B-F, five new triterpenoid saponins from the leaves of Schefflera mannii (Hook.f.) Harms

Fifteen triterpenoid saponins including five new compounds (Mannioside B: 3β-[(β-d-glucopyranosyl)oxy]urs-12-en-28-oic acid α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (1), mannioside C: 3β-[(β-d-glucopyranosyl)23-dioxy]urs-12-en-28-oic acid α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (2), mannioside D: 3β,23-dihydroxyurs-12-en-28-oic acid β-d-glucopyranosyl-(1 → 6)- β-d-glucopyranosyl ester (3), mannioside E: 3β-hydroxy-23-oxolup-20(29)-en-28-oic acid α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (4) and mannioside F: (22S)-27β-[(β-d-glucopyranosyl)oxy]-22-hydroxyprotosta-12,24-dien-3β-yl β-d-glucopyranoside (5)) were isolated from the leaves of Schefflera mannii (Hook.f.) Harms. Their structures were established on the basis of 1D and 2D NMR data, mass spectrometry and chemical methods. The major isolated compounds were tested for their antiproliferative activity on human malignant epithelial (HeLa) cells but were not efficient at the concentration of 33 mM.

Clarification of the Saponin Composition of Ranunculus ficaria Tubers

Six known saponins, glycosides of hederagenin and oleanolic acid, have been isolated from the tubers of Ranunculus ficaria L. (Ranunculaceae). Their separation included the use of centrifugal partition chromatography (CPC). Structure determination was achieved on the basis of chemical evidence and extensive spectral studies. This is the first report of these triterpene glycosides from R. ficaria.

A new flavonoid glycoside (APG) isolated from Clematis tangutica attenuates myocardial ischemia/reperfusion injury via activating PKCε signaling

Clematis tangutica has been shown to be beneficial for the heart; however, the mechanism of this effectremains unknown. Apigenin-7-O-β-D-(-6″-p-coumaroyl)-glucopyranoside (APG) is a new flavonoid glycoside isolated from Clematis tangutica. This study investigates the effects of APG on myocardial ischemia/reperfusion (IR) injury (IRI). An IRI model of primary myocardial cells and mice was used in this study. Compared with the IR group, APG preconditioning is protective against IRI in primary myocardial cells and in mice hearts in a dose-dependent manner. The cardioprotective mechanisms of APG may involve a significant PKCε translocation into the mitochondria and an activation of the Nrf2/HO-1 pathway, which respectively suppressesmitochondrial oxidative stress and inhibits apoptosis. In addition, PKCε-targeted siRNA and a PKCε specialized inhibitor (ε-V1-2) were used to inhibit PKCε expression and activity. The inhibition of PKCε reversed the cardioprotective effect of APG, with an inhibition of Nrf2/HO-1 activation and increased mitochondrial oxidative stress and cardiomyocyte apoptosis. In conclusion, PKCε activation plays an important role in the cardioprotective effects of APG. PKCε activation induced by APG preconditioning reduces mitochondrial oxidative stress and promotes Nrf2/HO-1-mediated anti-apoptosis signaling.

Apigenin-7-O-β-D-(-6''-p-coumaroyl)-Glucopyranoside Treatment Elicits Neuroprotective Effect against Experimental Ischemic Stroke

Stroke is the major cause of permanent disability and mortality in China. Apigenin-7-O-β-D-(-6''-p-coumaroyl)-glucopyranoside (APG) is a glycoside subtype of apigenin and has the antioxidant activity; however, whether and how it plays a neuroprotective role following cerebral ischemia remains unknown. In present study, we adopted the oxygen glucose/reperfusion model in PC12 cells, bilateral common carotid artery occlusion model in C57B6 mice and middle cerebral artery occlusion model in SD rats to observe the therapeutic effects of APG on ischemic stroke. We also discussed the underlying mechanism. Treatment with 0.4 μg/ml or 0.8 μg/ml APG promoted cell viability and proliferation, reduced LDH release and apoptotic cell death levels in PC12 cells. Treatment with 50 mg/kg or 100 mg/kg APG at 30 minutes after reperfusion improved neurological outcomes in vivo, as demonstrated by elevation of neurological scores in both mice and rats. It also increased the number of survival neurons in mice and reduced infarct volume in rats. APG also increased the contents of Mn-SOD and the phosphorylation level of STAT3, elevated the antioxidant activity and reduced oxidative productions. These findings revealed a neuroprotective effect of APG, which possibly induced by the STAT3 phosphorylation-mediated Mn-SOD up-regulation.

Antifungal properties of a new terpernoid saponin and other compounds from the stem bark of Polyscias fulva Hiern (Araliaceae)

BACKGROUND

In our previous studies, it was evident that the dichloromethane-methanol (1:1 v/v) stem barks extract of Polyscias fulva and fractions (ethyl acetate, n-butanol and residue) demonstrated interesting antidermatophytic activities. So, as a continuity of that, this work aimed at identifying active principles with antifungal properties from P. fulva that could be used as markers for possible standardization of this plant as phytomedicine.

METHODS

The ethyl acetate, n-butanol and residual fractions of the dichloromethane-methanol (1:1 v/v) stem bark extract of Polyscias fulva were further fractionated by column chromatography and the structures of isolated compounds elucidated based on their spectroscopic data in comparison with existing literature information. Antifungal activity was assayed by broth microdilution techniques on yeasts and dermatophytes spores.

RESULTS

The fractionation of the crude dichloromethane-methanol (1:1 v/v) stem bark extract of Polyscias fulva led to the isolation of 10 known compounds (1 to 10) and one new saponin (11: 3-O-[α-L-rhamnopyranosyl (1-2)-α-L-arabinopyranosyl]-28-O-[α-L-4-O-acetyl-rhamnopyranosyl (1-4)-β-D-glucopyranosyl-(1-6)-β-D-glucopyranosyl]-hederagenin). Among these compounds, 3-O-α-L- arabinopyranosyl-hederagenin and 3-O-[α-L-rhamnopyranosyl (1-2)-α-L-arabinopyranosyl]-hederagenin were the most active on the tested fungi with MIC values ranging from 0.78 to 100 μg/ml against both yeasts and dermatophytes.

CONCLUSION

The results of this work constitute a step forward in the possible development of an antidermatophytic phytomedicine from Polyscias fulva stem bark, the isolated compounds being possible markers for the standardisation.

Triterpenoid saponins from the roots of Clematis argentilucida

Reinvestigation of the n-BuOH extract of the roots of Clematis argentilucida led to the isolation of a new ursane-type triterpenoid saponin 1 and a new taraxerane-type saponin 2, four known saponins 3-6 first isolated from the species, together with seven saponins 7-13 reported in the previous papers. The structures of saponins 1-6 were elucidated by extensive spectroscopic analysis and chemical evidences. The ursane-type and taraxerane-type triterpenoid saponins were obtained from genus Clematis for the first time, and the aglycone of saponin 1, 3β,28-dihydroxy-18αH-ursan-20-en was first encountered. The cytotoxicity of all the saponins was evaluated against human glioblastoma U251MG cell lines. The monodesmosidic saponins 1, 2 and 4-8 exhibited cytotoxic activity against the cells with IC50 values ranging from 6.95 to 38.51 μM.

The genus Clematis (Ranunculaceae): chemical and pharmacological perspectives

ETHNOPHARMACOLOGICAL RELEVANCE

Twenty six species of the genus Clematis (Ranunculaceae) have been traditionally used in various systems of medicine for the treatment of ailments such as nervous disorders, syphilis, gout, malaria, dysentry, rheumatism, asthma, and as analgesic, anti-inflammatory, diuretic, antitumour, antibacterial and anticancer.

AIM OF THE REVIEW

To emphasize on ethnopharmacology, chemical constituents, pharmacology, toxicology and clinical studies of various species of the genus Clematis.

MATERIALS AND METHODS

The available information on Clematis species was collected through electronic search of major scientific databases.

RESULTS

A survey of literature revealed that triterpene saponins, alkaloids, flavonoids, lignans, steroids, coumarins, macrocyclic compounds, phenolic glycosides, anemonin and volatile oils constitute major classes of chemical constituents in the genus Clematis. Preliminary analgesic, anticancer, anti-inflammatory, diuretic, antiarthritis, hepatoprotective, hypotensive and HIV-1 protease inhibitor activity studies have been carried out on crude extracts of 26 traditionally used and medicinally promising species of Clematis genus.

CONCLUSIONS

The species of the genus Clematis emerged as good source of traditional medicine for the treatment of various ailments. Although few experimental studies validated their traditional claims, but employed uncharacterized crude extracts. Such Clematis species need to be explored properly following bioactivity-directed fractionation with a view to isolate bioactive constituents, and to evaluate their possible mode of actions. These species hold great potential for detailed clinical studies so that these could be exploited as potential drugs. The review will help researchers to select medicinally potential species of Clematis genus for future research.

New resistance-correlated saponins from the insect-resistant crucifer Barbarea vulgaris

Isolation and characterization of plant constituents responsible for insect resistance are of the utmost importance for better understanding of insect-host plant interactions, for selection and breeding of resistant plant varieties, and for development of natural insecticides to be used in future sustainable agriculture and food production. In this study, 3-O-cellobiosyl-cochalic acid (1), 3-O-cellobiosyl-gypsogenin (3), and 3-O-cellobiosyl-4-epihederagenin (4) were isolated from the glabrous type of Barbarea vulgaris var. arcuata exhibiting resistance to the flea beetle Phyllotreta nemorum. In addition to the new constituents, 3-O-cellobiosyl-hederagenin (2), a known insect repellant, was identified. The structures were established by one- and/or two-dimensional homo- and heteronuclear NMR experiments acquired at 800 MHz and by fragmentation and high-resolution mass spectrometric analysis. Compounds 1, 3, and 4 are glycosides of cochalic acid, gypsogenin, and 4-epihederagenin, respectively, none of which have previously been identified in Brassicaceae. Compounds 3 and 4 have both recently been targeted as unidentified constituents exhibiting correlation with P. nemorum resistance, but this is the first report of their structures.

Triterpenoid saponins from the stems of Clematis parviloba

Sixteen triterpenoid saponins (1-16) were isolated from the stems of Clematis parviloba, including a new compound, parvilobaside A (1), which was established as 23-O-acetyl-hederagenin-3-O-beta-D-ribopyranosyl-(1 --> 3)-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-l-arabinopyranoside on the basis of various spectroscopic techniques and chemical evidences. Among the isolated compounds, clematoside S (2) and alpha-hederin (4) showed moderate cytotoxic activities against four human tumor cell lines (HCT-8, Bel-7402, BGC-823, and A-2780) with IC(50) values in the range of 1.44-6.86 microg/ml.

Alkaloids and saponins from blue cohosh

Blue cohosh, Caulophyllum thalictroides (L.) Michx. (Berberidaceae), is used primarily to cure menstrual disturbances and to ease childbirth. Alkaloids and saponins are considered to be responsible for its pharmacological activity. A detailed phytochemical investigation of blue cohosh resulted in the isolation of 15 compounds belonging to the alkaloids and the triterpene saponins. The structures of two alkaloids, caulophyllumines A (1) and B (2) and a saponin, cauloside H (3) both previously unknown were determined by spectroscopic techniques, including by 1- and 2-D NMR as well as by chemical analysis.

Chemical components from Gentiana aristata

Two new, highly oxygenated ursane-type triterpenoids with an epidioxy function, compounds 1 and 2, as well as a new stanside-derived iridoid, compound 10, were isolated from the EtOH extract of Gentiana aristata (whole plant), together with 14 known constituents. The structures of the new compounds were established on the basis of detailed spectroscopic investigations, such as 1D- and 2D-NMR spectroscopy, as well as by means of HR-MS. Compounds 3 and 5-9 were screened in vitro for their cytotoxicities against human promyelocytic leukemia (HL-60), human ovarian (HO-8910), and human lung epithelia (A-549) cancer cells.

Triterpenoid saponins and phenylethanoid glycosides from stem of Akebia trifoliata var. australis

A detailed phytochemical study on the 70% aqueous ethanol extract of stems of Akebia trifoliata (Thunb.) Koidz. var. australis (Diels) Rehd led to isolation of five compounds, together with 12 known triterpenoid saponins and three known phenylethanoid glycosides. The structures of the five compounds were elucidated on the basis of analysis of spectroscopic data and physicochemical properties as: 2alpha, 3beta, 23-trihydroxy-30-norolean-12-en-28-oic acid beta-D-glucopyranosyl ester (1), 2alpha, 3beta, 23-trihydroxy-30-norolean-12-en-28-oic acid beta-D-xylopyranosyl-(1-->3)-O-alpha-D-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (2), 2alpha, 3beta, 23-trihydroxyurs-12-en-28-oic acid beta-D-xylopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (3), 3-beta-[(beta-D-glucopyranosyl-(1-->3)-O-alpha-L-arabinopyranosyl)oxy]-23-hydroxy-30-norolean-12-en-28-oic acid alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (4) and 3-beta-[(alpha-L-xylopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl)oxy]-30-norolean-12-en-28-oic acid alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (5), named mutongsaponin A, B, C, D and E, respectively.

Synthesis of beta-hederin and Hederacolchiside A1: triterpenoid saponins bearing a unique cytotoxicity-inducing disaccharide moiety

A facile synthetic approach toward oleanolic acid glycoside bearing alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl moiety, a unique oligosaccharide that strongly induces antitumor activity of oleanane-type triterpenoid saponins, was developed. Based on this approach beta-hederin (oleanolic acid 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside) was efficiently prepared from oleanolic acid through stepwise glycosylation in linear eight steps with 52% overall yield, while Hederacolchiside A1 (oleanolic acid 3-O-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->4)]-alpha-L-arabinopyranoside) in linear 13 steps with 20% overall yield.

Biological activities and distribution of plant saponins

Plant saponins are widely distributed amongst plants and have a wide range of biological properties. The more recent investigations and findings into their biological activities were summarized. Isolation studies of saponins were examined to determine which are the more commonly studied plant families and in which families saponins have been identified.

Antimicrobial activity of extracts of Clematis vitalba towards pathogenic yeast and yeast-like microorganisms

A broad activity against pathogenic yeast and yeast-like microorganisms was shown in crude extracts of young shoots of Clematis vitalba. MICs ranging from 1.4 to 12.3 microg/ml were observed. After fractionating with petroleum ether, ethyl acetate and methanol, antimycotic activity has been observed only in methanol fractions.