Oleanolic glycosides from Pometia ridleyi

Hedyocoronins A and B: two new oleanane saponins from the aerial parts of Hedyotis coronaria

Two new oleanane saponins, hedyocoronin A (1) and hedyocoronin B (2), were isolated from the aerial parts of Hedyotis coronaria (Kurz) Craib, Rubiaceae, collected at Da Oai district, Lam Dong province in Vietnam. Their chemical structures were elucidated by HR-MS, 1D and 2D-NMR spectra, along with the comparison with those reported in the literature. Compounds 1 and 2 showed weak cytotoxicity against KB and HeLa-S3 cancer cell lines with IC₅₀ values of more than 54 µM.

Anti-phytopathogen terpenoid glycosides from the root bark of Chytranthus macrobotrys and Radlkofera calodendron

Chytranthus macrobotrys and Radlkofera calodendron are two Sapindaceae characterized by a lack of phytochemical data. Both root barks from the two Sapindaceae species were processed by ethanol extraction followed by the isolation of their primary constituents by liquid chromatography. This process yielded four previously undescribed terpenoid glycosides together with eight known analogues. Extracts and isolated compounds from C. macrobotrys and R. calodendron were then screened for antimicrobial activity against fifteen phytopathogens. The biological screening also involved extracts and pure compounds from Blighia unijugata and Blighia welwitschii, two Sapindaceae previously studied by our group. Phytopathogens were chosen based on their economic impact on agriculture worldwide. The selection was composed primarily of fungal species including; Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Zymoseptoria tritici, Fusarium oxysporum, Botrytis cinerea, Pythium spp., Trichoderma spp. and Rhizoctonia solani. Furthermore, pure terpenoid glycosides were tested for the first time against wood-inhabiting phytopathogens such as; Phaeomoniella chlamydospora, Phaeoacremonium minimum, Fomitiporia mediterranea, Eutype lata and Xylella fastidiosa. Raw extracts exhibited different levels of activity dependent on the organism. Some pure compounds, including 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (α-hederin), 3-O-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (macranthoside A) and 3-O-α-L-arabinopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (clemontanoside C), exhibited significant growth inhibitions on Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Fomitiporia mediterranea and Zymoseptoria tritici. Monodesmoside triterpene saponins, in particular, exhibited MIC (IC₁₀₀) values as low as 25 μg/ml and IC₅₀ values as low as 10 μg/ml against these phytopathogens. Structure-activity relationships, as well as plant-microbe interactions, were discussed.

The formation and antibacterial activity of Zn/ZnO nanoparticle produced in Pometia pinnata leaf extract solution using a laser ablation technique

The single-step green synthesis has been successfully established to prepare a bi-phase structure of Zn/ZnO nanoparticles using laser ablation in a liquid medium. Nd: YAG laser with the wavelength of 1064 nm was employed to perform the laser ablation in pure water and Pometia pinnata (P. pinnata) leaf extract, with the leaf, were extracted in pure water and some concentration of ethanol. ZnO nanoparticles can be obtained via laser ablation in pure water, while the usage of P. pinnata leaf extract as the solution has caused the appearance of the bi-phase Zn/ZnO nanostructure. X-ray diffraction (XRD) pattern indicates the appearance of Zn peaks alongside with ZnO peaks with the inclusion of P. pinnata leaf extract. Transmission electron microscope (TEM) images show the change of shape from the rod-like shape into a spherical shape and smaller size spherical shape of Zn/ZnO nanoparticles in comparison with ZnO. Noticeable change of UV-visible spectrum emerges as the water was substituted by P. pinnata leaf extract. The zeta potential of Zn/ZnO prepared with P. pinnata extracted in water, with the value of - 18.9 V, reduces down to - 43.5 and - 41.1 for 20-40% of ethanol concentration, respectively. The as-prepared ZnO and Zn/ZnO colloidal samples were evaluated for their antibacterial activities against two strains Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Zn/ZnO sample shows a more substantial antibacterial effect in comparison with pure ZnO, no bacteria alive after 12 and 24 h' treatment for E. coli and S. aureus, respectively.

Hederagenin glycosides from the fruits of Blighia unijugata

A phytochemical investigation of Blighia unijugata led to the isolation of eleven hederagenin glycosides. Among these compounds, six are previously undescribed, two are described in their native forms for the first time and three are known whereas firstly isolated from Blighia unijugata. The structure of the undescribed compounds was elucidated on the basis of 2D NMR and mass spectrometry analyses as 3-O-β-D-xylopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-β-D-xylopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-3-O-acetyl-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-β-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-β-D-xylopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-β-D-xylopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-3-O-acetyl-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl ester, 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-β-D-glucopyranosyl ester and 3-O-β-D-xylopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin 28-O-β-D-glucopyranosyl ester. These results revealed the existence of several conserved structural features that could be used as chemotaxonomic markers for the Blighia genus such as the glycosidic sequence 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl, the occurrence of 3-O-acetylated β-D-glucopyranosyl units and the systematic presence of hederagenin as aglycone.

Two new phenolic compounds and some biological activities of Scorzonera pygmaea Sibth. & Sm. subaerial parts

Phytochemical composition of ethyl acetate fraction and total phenolic content, in vitro antioxidant, anti-inflammatory, antimicrobial activities of petroleum ether, chloroform, ethyl acetate and n-butanol fractions of the ethanol extract obtained from the subaerial parts of Scorzonera pygmaea Sibth. & Sm. (Asteraceae) were investigated. Nine compounds; scorzopygmaecoside (1), scorzonerol (2), cudrabibenzyl A (3), thunberginol C (4), scorzocreticoside I (5) and II (6), chlorogenic acid (7), chlorogenic acid methyl ester (8), 3,5-di-O-caffeoylquinic acid (9) were isolated and identified using spectroscopic methods. All substances were isolated for the first time from this species. Compounds 1 and 2 are new. The fractions showed high antioxidant capacity correlated with their phenolic content and no significant antimicrobial activity against tested bacteria and fungi. COX inhibition test was used to evaluate the anti-inflammatory activity and all the fractions showed low inhibition in comparison with indomethacin.

Inhibition of Glucose Transport by Tomatoside A, a Tomato Seed Steroidal Saponin, through the Suppression of GLUT2 Expression in Caco-2 Cells

We investigated whether tomatoside A (5α-furostane-3β,22,26-triol-3-[O-β-d-glucopyranosyl (1→2)-β-d-glucopyranosyl (1→4)-β-d-galactopyranoside] 26-O-β-d-glucopyranoside), a tomato seed saponin, may play a role in the regulation of intestinal glucose transport in human intestinal Caco-2 cells. Tomatoside A could not penetrate through Caco-2 cell monolayers, as observed in the transport experiments using liquid chromatography-mass spectrometry. The treatment of cells with 10 μM tomatoside A for 3 h resulted in a 46.0% reduction in glucose transport as compared to untreated cells. Western blotting analyses revealed that tomatoside A significantly (p < 0.05) suppressed the expression of glucose transporter 2 (GLUT2) in Caco-2 cells, while no change in the expression of sodium-dependent glucose transporter 1 was observed. In glucose transport experiments, the reduced glucose transport by tomatoside A was ameliorated by a protein kinase C (PKC) inhibitor and a multidrug resistance-associated protein 2 (MRP2) inhibitor. The tomatoside A-induced reduction in glucose transport was restored in cells treated with apical sodium-dependent bile acid transporter (ASBT) siRNA or an ASBT antagonist. These findings demonstrated for the first time that the nontransportable tomato seed steroidal saponin, tomatoside A, suppressed GLUT2 expression via PKC signaling pathway during the ASBT-influx/MRP2-efflux process in Caco-2 cells.

ESI-MS2 and Anti-inflammatory Studies of Cyclopropanic Triterpenes. UPLC-ESI-MS and MS2 Search of Related Metabolites from Donella ubanguiensis

INTRODUCTION

Triterpenes are one of the largest secondary metabolites groups spread in the plant kingdom with various skeletons. These metabolites have showed various bioactivities including anti-inflammatory activity.

OBJECTIVE

The study aims to explore the mass spectrometry fragmentation of donellanic acids A-C (DA A-C), three compounds identified from Donella ubanguiensis; in addition, the fragmentation behaviour of these metabolites will serve as a fingerprint to search and characterise triterpenes congeners in fruits, bark and wood crude extracts of D. ubanguiensis. This work was prompted by the anti-inflammatory activity on leukocyte migration, exudate concentrations and myeloperoxidase activity obtained for DA A-B.

METHODOLOGY

The bioactivity was performed on mouse model of pleurisy induced by carrageenan and the parameters were analysed by veterinarian automated cell counter and colorimetric assays. While the tandem mass analyses of DA A-C were carried out by a direct infusion ESI-QTOF-MS/MS, the extracts were studied by UPLC-ESI-QTOF-MS and UPLC-ESI-QTOF-MS/MS.

RESULTS

DA A displayed interesting anti-inflammatory activity by inhibiting leukocyte migration, exudate concentrations and myeloperoxidase activity (p < 0.05) while DA B was weakly active (p > 0.05). Moreover, the diagnostic of the MS² behaviour of DA A-C in conjunction with the chromatograms and the obtained MS² data of the crude extract led to the characterisation of three cyclopropane triterpenes (T1-T3) and six saponins (T4-T9) from the fruits, the bark, and the wood extracts.

CONCLUSIONS

Donella species deserve more investigation since metabolites related to the anti-inflammatory compound (DA A) could be identified. Copyright © 2016 John Wiley & Sons, Ltd.

New triterpenoidal saponins from Koelreuteria paniculata

Bioassay guided fractionation and chemical investigation of the ethanolic extract of the aerial parts of Koelreuteria paniculata Laxm. (Sapindaceae), resulted in the isolation and identification of three new triterpenoid saponins 1-3 named Paniculatosoid A-C, along with eleven known compounds. The structures of the isolated compounds were elucidated using 1D and 2D NMR experiments, HRESIMS, and comparison with literature data. The occurrence of tridesmosidic saponin is reported for the first time from family Sapindaceae, as well as it is rarely found in natural saponins. Compounds 4-13 were evaluated for their antibacterial, antifungal, antimalarial and antileishmanial activities. Compound 12 showed weak antibacterial activity against Escherichia coli with an IC₅₀ value of 101 μM. Compounds 12 and 13 showed antimalarial activity against chloroquine-sensitive (D6) Plasmodium falciparum protozoan with IC₅₀ values of 6.46 and 6.95 μM, and against chloroquine-resistant (W2) Plasmodium falciparum protozoan with IC₅₀ values of 9.34 and 4.18 μM.

Field-amplified sample stacking β-cyclodextrin modified capillary electrophoresis for quantitative determination of diastereomeric saponins

Successful simultaneous diastereomeric separation and sensitive determination of two pairs of triterpenoidal saponins have been achieved by capillary electrophoresis (CE) using β-cyclodextrin (β-CD) as a stereoselective agent to cooperate with borate complexation. A usual technique for isolation and group separation of saponins was developed as an appropriate purification step prior to the determination of individual saponins by CE. Soyasaponin I ( S1: ), azukisaponin V ( S2: ), bersimoside I ( S3: ) and bersimoside II ( S4: ) could be well separated within 14 min in a fused-silica capillary (60 cm long to the detector with an additional 10 cm to the cathode; 75 µm i.d.). The background electrolyte was borate buffer (80 mM, pH 10), containing 24 mM β-CD. The separation voltage was 14 kV with a detection wavelength of 195 nm. The sample was electrokinetically injected using a voltage of 16 kV for 12 s. Methanol (70%) was used as the diluent for field-amplified sample stacking after hydrodynamic injection of short water plug (5 cm, 4 s). The method was partially validated for linearity, repeatability, reproducibility, limits of detection and limits of quantification. The correlation coefficients of the calibration curves were all >0.998, and the recoveries were from 98.23 to 96.21%.

Studies on cytotoxic triterpene saponins from the leaves of Aralia elata

Aralia elata has long been used as a tonic, anticancer and antidiabetic agent in China and Japan, and is widely consumed as food. Phytochemical investigation of the leaves of A. elata has led to the isolation of four new compounds, 3-O-[β-D-glucopyranosyl(1 → 3)-β-D-glucopyranosyl] echinocystic acid 28-O-β-D-glucopyranosyl ester (congmuyenoside I, 1), 3-O-[β-D-glucopyranosyl(1 → 2)-β-D-glucopyranosyl] hederagenin 28-O-β-D-glucopyranosyl ester (congmuyenoside II, 2), 3-O-{[β-D-glucopyranosyl(1 → 2)]-[β-D-glucopyranosyl(1 → 3)-β-D-glucopyranosyl(1 → 3)]-β-D-glucopyranosyl} echinocystic acid 28-O-β-D-glucopyranosyl ester (congmuyenoside III, 3) and 3-O-β-D-glucopyranosyl caulophyllogenin 28-O-β-D-glucopyranosyl ester (congmuyenoside IV, 4), and eight known triterpene saponins (5-12). The structural determination was accomplished with spectroscopic analysis, in particularly (13)C NMR, 2D NMR and HR-ESI-MS techniques. In addition, compounds 5–10 were found for the first time in the genus Aralia. Compounds 1-12 were tested for their inhibition of the growth of HL60, A549 and DU145 cancer cells. In addition, compound 8 showed significant cytotoxic activities against HL60, A549 and DU145 cancer cells with IC(50) values of 15.62, 11.25 and 7.59 μM, respectively.

Saponins, classification and occurrence in the plant kingdom

Saponins are a structurally diverse class of compounds occurring in many plant species, which are characterized by a skeleton derived of the 30-carbon precursor oxidosqualene to which glycosyl residues are attached. Traditionally, they are subdivided into triterpenoid and steroid glycosides, or into triterpenoid, spirostanol, and furostanol saponins. In this study, the structures of saponins are reviewed and classified based on their carbon skeletons, the formation of which follows the main pathways for the biosynthesis of triterpenes and steroids. In this way, 11 main classes of saponins were distinguished: dammaranes, tirucallanes, lupanes, hopanes, oleananes, taraxasteranes, ursanes, cycloartanes, lanostanes, cucurbitanes, and steroids. The dammaranes, lupanes, hopanes, oleananes, ursanes, and steroids are further divided into 16 subclasses, because their carbon skeletons are subjected to fragmentation, homologation, and degradation reactions. With this systematic classification, the relationship between the type of skeleton and the plant origin was investigated. Up to five main classes of skeletons could exist within one plant order, but the distribution of skeletons in the plant kingdom did not seem to be order- or subclass-specific. The oleanane skeleton was the most common skeleton and is present in most orders of the plant kingdom. For oleanane type saponins, the kind of substituents (e.g. -OH, =O, monosaccharide residues, etc.) and their position of attachment to the skeleton were reviewed. Carbohydrate chains of 18 monosaccharide residues can be attached to the oleanane skeleton, most commonly at the C3 and/or C17 atom. The kind and positions of the substituents did not seem to be plant order-specific.

New ether diglycosides from Matayba guianensis with antiplasmodial activity

Four new ether diglycosides (1-4), named matayosides A-D, were isolated from the root bark of Matayba guianensis, a plant exhibiting in vitro antiplasmodial activity. They were identified as hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-palmitoyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-4,6-di-O-acetyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-3,6-di-O-acetyl-beta-D-glucopyranoside and hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-acetyl-beta-D-glucopyranoside, respectively. Their structures were established using one- and two-dimensional NMR techniques, mass spectrometry (MS) and MS/MS experiments. The compounds were found to inhibit the growth of Plasmodium falciparum in vitro with IC50 values ranging from 2.5 to 8.9 microg/mL.

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.