Orientation of membrane fragments by electric field

Purple membrane fragments from Halobacterium halobium were oriented by a static electric field in a water suspension. It was found that an electric field of approx. 20 V/cm is sufficient to achieve practically complete orientation; the purple membranes have a permanent electric dipole moment of (6 ±1)· 10^?23 C · m, the orientation of the retinal transition moment relative to the direction of the electric dipole moment, θ, is (59 ± 1)⁰, and the purple membrane rotational diffusion constant D_rot = 0.65 s^?1. It was found that because of the electrophoretic movement of the particles a hydrodynamic velocity gradient builds up which also orients the purple membranes.     

New oleanane-type saponins: Leptocarposide B-D,from Ludwigia leptocarpa (Onagraceae)

Three new oleanane-type saponins, leptocarposide B-D (1–3), were isolated from the whole plant of Ludwigia leptocarpa (Nutt.) Hara, together with ten known compounds 4–13.The structures of these compounds were determined by interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (¹H, ¹³C) and 2D-NMR (¹H–¹H COSY, HSQC, HMBC, and NOESY), and by comparison with the literature data. The structures of the new compounds were established as 28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[α-l-arabinopyranosyl-(1 → 3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (1); 3-O-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl medicagenic acid (2); 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[α-l- arabinopyranosyl-(1 → 3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (3).     

Thermotropic and barotropic phase transitions of N-methylated dipalmitoylphosphatidylethanolamine bilayers

In order to understand the effect of polar head group modification on the thermotropic and barotropic phase behavior of phospholipid bilayer membranes, the phase transitions of dipalmitoylphosphatidylethanolamine (DPPE), dipalmitoylphosphatidyl-N-methylethanolamine (DPMePE), dipalmitoylphosphatidyl-N,N-dimethylethanolamine (DPMe₂PE) and dipalmitoylphosphatidylcholine (DPPC) bilayer membranes were observed by differential scanning calorimetry and high-pressure optical methods. The temperatures of the so-called main transition from the gel (L_β) or ripple gel (P_β′) phase to the liquid crystalline (L_α) phase were almost linearly elevated by applying pressure. The slope of the temperature-pressure boundary, dT/dp, was in the range of 0.220-0.264 K MPa⁻¹ depending on the number of methyl groups in the head group of lipids. The main-transition temperatures of N-methylated DPPEs decreased with increasing size of head group by stepwise N-methylation. On the other hand, there was no significant difference in thermodynamic quantities of the main transition between the phospholipids. With respect to the transition from the subgel (L_c) phase to the lamellar gel (L_β or L_β′) phase, the transition temperatures were also elevated by applying pressure. In the case of DPPE bilayer the L_c/L_β transition appeared at a pressure higher than 21.8 MPa. At a pressure below 21.8 MPa the L_c/L_α transition was observed at a temperature higher than the main-transition temperature. The main (L_β/L_α) transition can be recognized as the transformation between metastable phases in the range from ambient pressure to 21.8 MPa. Polymorphism in the gel phase is characteristic of DPPC bilayer membrane unlike other lipid bilayers used in this study: the L_β′, P_β′ and pressure-induced interdigitated gel (L_βI) phases were observed only in the DPPC bilayer. Regarding the bilayers of DPPE, DPMePE and DPMe₂PE, the interdigitation of acyl chain did not appear even at pressures as high as 200 MPa.     

Dianthus erinaceus var. erinaceus: Extraction,isolation, characterization and antimicrobial activity investigation of novel saponins

A phytochemical analysis of Dianthus erinaceus Boiss. var. erinaceus (Caryophyllaceae) has led to the isolation of two novel triterpenoid saponins, containing an oleane type skeleton, named dianosides K and L (1, 2), along with six known triterpenoid saponins (3–8). On the basis of chemical and spectrometric data, the structures of the new compounds were elucidated as 3-O-[β-d-glucopyranosyl (1 → 3)]–[β-d-glucopyranosyl (1 → 6)]-β-d-glucopyranosyl-olean-12-ene-23α,28-β–dioic acid 28-O-β-d-glucopyranosyl ester (1) and 3-O-[β-d-glucopyranosyl (1 → 3)]–[β-d-glucopyranosyl(1 → 6)]-β-d-glucopyranosyl-olean-12-ene-23α,28-β-dioic acid 28-O-α-l-mannopyranosyl (1 → 6)-β-d-glucopyranosyl ester (2). All isolated natural compounds were structurally characterized by 1D- (¹H, ¹³C, DEPT); 2D- (COSY, HMQC, HMBC) NMR and HR-ESI/MS methods. The antimicrobial activity of compounds 1 and 2 were tested against four Gram-negative, three Gram-positive bacteria and the yeast Candida albicans by the MIC method.     

Vavilosides A1/A2–B1/B2, new furostane glycosides from the bulbs of Allium vavilovii with cytotoxic activity

A phytochemical analysis of the bulbs of Allium vavilovii M. Pop. & Vved. was attained for the first time extensively, affording to the isolation of four new furostanol saponins, named vavilosides A1/A2–B1/B2 (1a/b–2a/2b), as two couple of isomers in equilibrium, together with ascalonicoside A1/A2 (3a/3b) and 22-O-methyl ascalonicoside A1/A2 (4a/4b), previously isolated from shallot, Allium ascalonicum. High concentrations of kaempferol, kaempferide, and kaempferol 4^I-glucoside were also isolated. The chemical structures of the new compounds, established through a combination of extensive nuclear magnetic resonance, mass spectrometry and chemical analyses, were identified as (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-galactopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside A1), (25R)-furost-5(6)-en-1β,3β,22β,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-galactopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside A2), (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-xylopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside B1), (25R)-furost-5(6)-en-1β,3β,22β,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-xylopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside B2). The isolated saponins showed cytotoxic activity on J-774, murine monocyte/macrophage, and WEHI-164, murine fibrosarcoma, cell lines with the following rank: vaviloside B1/B2 > ascalonicoside A1/A2 > vaviloside A1/A2.     

The conversion of 5α-lanost-24-ene-3β,9α-diol and parkeol into poriferasterol by the alga Ochromon as malhamensis

The 4,4-dimethylsterols 4α-lanost-24-ene-3β,9α-diol-[2-³H₂] and parkeol-[2-³H₂] were synthesized from lanosterol and subsequently incubated with cultures of Ochromonas malhamensis. 5α-Lanost-24-ene-3β,9α-diol was converted into poriferasterol with three times the efficiency of parkeol. Clionasterol was also found to be labelled from both parkeol and 5α-lanost-24-ene-3β,9α-diol. No significant incorporation of radioactivity into sterols was obtained after feeding 5α-lanost-24-ene-3β,9α-diol to higher plants, the chlorophyte alga Trebouxia, yeast or a cell free homogenate of rat liver.     

Identification of N, O-diacetyl-, N-acetyl- and N-glycolylneuraminyl-(2 → 3)-lactose in rat urine

The structure of three neuraminyl-oligosaccharides isolated from rat urine-have been studied by chromatographic and mass spectrometric analyses of different hydrolysis and methylation products. The structures of the oligosaccharides were identifies as O-α-N-acetyl(O-acetyl)neuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose, O-α-N-acetylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose and O-α-N-glycolylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose.     

Triterpene glycosides from Astragalus icmadophilus

Six cycloartane-type triterpene glycosides were isolated from Astragalus icmadophilus along with two known cycloartane-type glycosides, five known oleanane-type triterpene glycosides and one known flavonol glycoside. The structures of the six compounds were established as 3-O-[α-L-arabinopyranosyl-(1 → 2)-O-3-acetoxy-α-L-arabinopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxycycloartane, 3-O-[α-L-rhamnopyranosyl-(1 → 2)-O-α-L-arabinopyranosyl-(1 → 2)-O-β-D-xylopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy cycloartane, 3-O-[α-L-arabinopyranosyl-(1 → 2)-O-3,4-diacetoxy-α-L-arabinopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxycycloartane, 3-O-[α-L-arabinopyranosyl-(1 → 2)-O-3-acetoxy-α-L-arabinopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,25-tetrahydroxy-20(R),24(S)-epoxycycloartane, 3-O-[α-L-arabinopyranosyl-(1 → 2)-O-β-D-xylopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,24α-tetrahydroxy-20(R),25-epoxycycloartane, 3-O-[α-L-rhamnopyranosyl-(1 → 2)-O-α-L-arabinopyranosyl-(1 → 2)-O-β-D-xylopyranosyl]-6-O-β-D-glucopyranosyl-3β,6α,16β,24α-tetrahydroxy-20(R),25-epoxycycloartane by the extensive use of 1D- and 2D-NMR experiments along with ESIMS and HRMS analysis.The first four compounds are cyclocanthogenin and cycloastragenol glycosides, whereas the last two are based on cyclocephalogenin as aglycone, more unusual in the plant kingdom, so far reported only from Astragalus spp.     

Electric field effects on red chlorophylls, β-carotenes and P700 in cyanobacterial Photosystem I complexes

We have probed the absorption changes due to an externally applied electric field (Stark effect) of Photosystem I (PSI) core complexes from the cyanobacteria Synechocystis sp. PCC 6803, Synechococcus elongatus and Spirulina platensis. The results reveal that the so-called C719 chlorophylls in S. elongatus and S. platensis are characterized by very large polarizability differences between the ground and electronically excited states (with Tr(Δα) values up to about 1000 ų f⁻²) and by moderately high change in permanent dipole moments (with average Δμ values between 2 and 3 D f⁻¹). The C740 chlorophylls in S. platensis and, in particular, the C708 chlorophylls in all three species give rise to smaller Stark shifts, which are, however, still significantly larger than those found before for monomeric chlorophyll. The results confirm the hypothesis that these states originate from strongly coupled chlorophyll a molecules. The absorption and Stark spectra of the β-carotene molecules are almost identical in all complexes and suggest similar or slightly higher values for Tr(Δα) and Δμ than for those of β-carotene in solution. Oxidation of P700 did not significantly change the Stark response of the carotenes and the red antenna states C719 and C740, but revealed in all PSI complexes changes around 700-705 and 690-693 nm, which we attribute to the change in permanent dipole moments of reduced P700 and the chlorophylls responsible for the strong absorption band at 690 nm with oxidized P700, respectively.     

Flavonoid glycosides of the black locust tree, Robinia pseudoacacia (Leguminosae)

Four flavone glycosides isolated from extracts of the leaves of Robinia pseudoacacia (Leguminosae) were characterised by spectroscopic and chemical methods as the 7-O-β-d-glucuronopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranosides of acacetin (5,7-dihydroxy-4′-methoxyflavone), apigenin (5,7,4′-trihydroxyflavone), diosmetin (5,7,3′-trihydroxy-4′-methoxyflavone) and luteolin (5,7,3′,4′-tetrahydroxyflavone). Assignment of glycosidic ¹H and ¹³C resonances in their NMR spectra was facilitated by ²J_HC correlations detected using the H2BC (heteronuclear two-bond correlation) pulse sequence. Spectroscopic analysis of two known triglycosides, acacetin 7-O-β-d-glucopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside (previously unrecorded from this species) and acacetin 7-O-β-d-xylopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside (‘acacetin trioside’), enabled inconsistencies in the literature relating to these structures to be resolved. Comparison of the flavonoid chemistry of leaves and flowers of R. pseudoacacia using LC-UV and LC-MS showed that flavone 7-O-glycosides, particularly of acacetin, predominated in the former, whereas the latter comprised mainly flavonol 3,7-di-O-glycosides, including several examples new to this species. Tissue dependent differences in flavonoid chemistry were also evident from the glycosylation patterns of the compounds.     

Electric birefringence study of the purple membrane of Halobacterium halobium

An electric birefringence study was carried out on aqueous suspensions of the purple membrane of Halobacterium halobium. In addition to the characterization of both native and modified membrane samples, the dependence of electric birefringence on pH and ionic strength was also investigated. The results indicate that purple membrane shows electric birefringence at a field strength as low as 200 V/cm. The permanent dipole moment and polarizability ranged from 20,500 debyes and 1.01 × 10^?14 cm³ for a purple membrane concentration of 0.40 mg/mL to 41,000 debyes and 2.05 × 10^?14 cm³ for a concentration of 0.80 mg/mL. It was also found that removal of the retinyl group of bacteriorhodopsin substantially decreases but does not eliminate the electric birefringence of the membrane. The solubilization of the membrane by Triton X-100, however, completely abolishes the electric birefringence. These experiments indicate that there is an interaction between adjacent bacteriorhodopsin molecules within the purple membrane via the retinyl chromophore moiety that builds up the permanent dipole moment. They also suggest that there are two types of response when purple membrane suspensions are placed in an electric field. One is an alignment of the disk-shaped particles with the field. The other is a stacking of the particles following their alignment by the electric field, which is promoted by the induced dipole moment.     

Enzymatically derived aldouronic acids from Cryptomeria japonica arabinoglucuronoxylan

An arabinoglucuronoxylan was extracted from the holocellulose of sugi (Cryptomeria japonica) wood with 10% KOH and subjected to hydrolysis by partially purified xylanase fraction from a commercial cellulase preparation “Meicelase”. Neutral sugars liberated were analyzed by size exclusion chromatography showing the presence of xylooligosaccharides up to xylohexaose. Aldouronic acids liberated were purified by preparative anion exchange chromatography. Their structures were identified by monosaccharide analysis, comparison of their volume distribution coefficients (Dvs) with those of the authentic samples in anion exchange chromatography and ¹H and ¹³C NMR spectroscopy, resulting in the characterization of eight aldouronic acids including acids consisting of two 4-O-Me-α-D-GlcAp residues and 3-5 D-Xyl residues.

1.

Fr. 1-S1: (aldohexaouronic acid, MeGlcA³Xyl₅), O-β-Xylp-(1 → 4)-O-β-D-Xylp-(1 → 4)-[O-(4-O-Me-α-D-GlcAp)-(1 → 2)]-O-β-Xylp-(1 → 4)-O-β-D-Xylp-(1 → 4)-D-Xyl

2.

Fr. 1-S2: (aldopentaouronic acid, MeGlcA³Xyl₄), O-β-Xylp-(1 → 4)-[O-(4-O-Me-α-D-GlcAp)-(1 → 2)]-O-β-D-Xylp-(1 → 4)-O-β-Xylp-(1 → 4)-D-Xyl

3.

Fr. 2-S1: (aldotetraouronic acid, MeGlcA³Xyl₃), O-(4-O-Me-α-D-GlcAp)-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-β-D-Xylp-(1 → 4)-D-Xyl

4.

Fr. 3-S1: (aldotetraouronic acid, GlcA³Xyl₃), O-(α-D-GlcAp)-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-β-Xylp-(1 → 4)-D-Xyl,

5.

Fr. 4-S1: (aldotriouronic acid, GlcA²Xyl₂), O-(4-O-Me-α-D-GlcAp)-(1 → 2)-O-β-D-Xylp-(1 → 4)-D-Xyl

6.

Fr. 4-S2: (MeGlc⁴MeGlcA³Xyl₅), O-β-D-Xylp-(1 → 4)-[O-(4-O-Me-α-D-GlcAp)]-(1 → 2)-O-β-D-Xylp-(1 → 4)-[O-(4-O-Me-α-D-GlcAp)]-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-β-D-Xylp-(1 → 4)-D-Xyl

7.

Fr. 6-S1: (MeGlcA⁴MeGlcA³Xyl₄), O-(4-O-Me-α-D-GlcAp)-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-[(4-O-Me-α-D-GlcAp)]-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-β-D-Xylp-(1 → 4)-D-Xyl

8.

Fr. 7-S1: (MeGlcA³MeGlc²Xyl₃), O-(4-O-Me-α-D-GlcAp)-(1 → 2)-O-β-D-Xylp-(1 → 4)-O-[(4-O-Me-α-D-GlcAp)]-(1 → 2)-O-β-D-Xylp-(1 → 4)-D-Xyl

Fr. 4-S2 was a new acidic oligosaccharide. The distribution pattern of these vicinal uronic acid units along the D-xylan chain was discussed.     

Antifungal saponins from bulbs of white onion,Allium cepa L.

Three saponins, named ceposide A, ceposide B, and ceposide C were isolated from the bulbs of white onion, Allium cepa L. Elucidation of their structure was carried out by comprehensive spectroscopic analyses, including 2D NMR spectroscopy and mass spectrometry, and chemical evidences. The structures of the compounds were identified as (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-d-xylopyranosyl 26-O-α-d-rhamnoyranosyl-(1 → 2)-O-β-d-galactopyranoside (ceposide A), (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-d-xylopyranosyl 26-O-α-d-rhamnoyranosyl-(1 → 2)-O-β-d-glucopyranoside (ceposide B), and (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-d-galactopyranosyl 26-O-α-d-rhamnoyranosyl-(1 → 2)-O-β-d-galactopyranoside (ceposide C). The isolated compounds, alone and in combinations, were evaluated for their antimicrobial activity on ten fungal species. Antifungal activity of all three saponins increased with their concentration and varied with the following rank: ceposide B > ceposide A–ceposide C. We found a significant synergism in the antifungal activity of the three ceposides against Botrytis cinerea and Trichoderma atroviride, because growth of these fungi was strongly inhibited when the three saponins were applied in combination. In contrast, Fusarium oxysporum f. sp. lycopersici, Sclerotium cepivorum and Rhizoctonia solani were very little affected by saponins.     

A new complex triterpenoid saponin from Samanea saman with haemolytic activity and adjuvant effect

A new complex triterpenoid saponin was isolated from the stem bark of Samanea saman by using chromatographic methods. Its structure was established as 3-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]-2,23-dihydroxy-(2β,3β,4α)-olean-12-en-28-oic acid O-β-d-glucopyranosyl-(1 → 3)-O-[O-β-d-glucopyranosyl-(1 → 4)]-O-6-deoxy-α-l-mannopyranosyl-(1 → 2)-6-O-[4-O-[(2E,6S)-2,6-dimethyl-1-oxo-2,7-octadienyl]-6-deoxy-α-l-mannopyranosyl)oxy]-β-d-glucopyranosyl ester (1). Structural elucidation was performed using detailed analyses of ¹H and ¹³C NMR spectra including 2D NMR spectroscopic techniques and chemical conversions. The haemolytic activity of the saponin was evaluated using in vitro assays, and its adjuvant potential on the cellular immune response against ovalbumin antigen was investigated using in vivo models.     

Glucosylation of the flavonoid, astragalin by Leuconostoc mesenteroides B-512FMCM dextransucrase acceptor reactions and characterization of the products

Astragalin (kaempferol-3-O-β-d-glucopyranoside, Ast) glucosides were synthesized by the acceptor reaction of a dextransucrase produced by Leuconostoc mesenteroides B-512FMCM with astragalin and sucrose. Each glucoside was purified and their structures were assigned as kaempferol-3-O-β-d-glucopyranosyl-(1 → 3)-O-α-d-glucopyranoside (or kaempferol-3-O-β-d-nigeroside, Ast-G1′) and kaempferol-3-O-β-d-glucopyranosyl-(1 → 6)-O-α-d-glucopyranoside (or kaempferol-3-O-β-d-isomaltoside, Ast-G1) for one glucose transferred, and kaempferol-3-O-β-d-isomaltooligosacharide (Ast-IMO or Ast-Gn; n = 2-8). The astragalin glucosides exhibited 8.3-60.6% higher inhibitory effects on matrix metalloproteinase-1 expression, 18.8-20.3% increased antioxidant effects, and 3.8-18.8% increased inhibition activity of melanin synthesis compared to control (without the addition of compound), depending on the number of glucosyl residues linked to astragalin. These novel compounds could be used to further expand the industrial applications of astragalin glucosides, in particular in the cosmetics industry.     

Triterpenoid saponins from a cytotoxic root extract of Sideroxylonfoetidissimum subsp. gaumeri

Evaluation of the cytotoxicity of an ethanolic root extract of Sideroxylonfoetidissimum subsp. gaumeri (Sapotaceae) revealed activity against the murine macrophage-like cell line RAW 264.7. Systematic bioassay-guided fractionation of this extract gave an active saponin-containing fraction from which four saponins were isolated. Use of 1D (¹H, ¹³C, DEPT135) and 2D (COSY, TOCSY, HSQC, and HMBC) NMR, mass spectrometry and sugar analysis gave their structures as 3-O-(β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl)-28-O-(α-l-rhamnopyranosyl-(1 → 3)[β-d-xylopyranosyl-(1 → 4)]-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-16α-hydroxyprotobassic acid, 3-O-β-d-glucopyranosyl-28-O-(α-l-rhamnopyranosyl-(1 → 3)[β-d-xylopyranosyl-(1 → 4)]-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-16α-hydroxyprotobassic acid, 3-O-(β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl)-28-O-(α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)[β-d-apiofuranosyl-(1 → 3)]-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-16α-hydroxyprotobassic acid, and the known compound, 3-O-β-d-glucopyranosyl-28-O-(α-l-rhamnopyranosyl-(1 → 3)[β-d-xylopyranosyl-(1 → 4)]-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-protobassic acid. Two further saponins were obtained from the same fraction, but as a 5:4 mixture comprising 3-O-(β-d-glucopyranosyl)-28-O-(α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)[β-d-apiofuranosyl-(1 → 3)]-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-16α-hydroxyprotobassic acid and 3-O-(β-d-apiofuranosyl-(1 → 3)-β-d-glucopyranosyl)-28-O-(α-l-rhamnopyranosyl-(1 → 3)[β-d-xylopyranosyl-(1 → 4)]-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl)-16α-hydroxyprotobassic acid, respectively. This showed greater cytotoxicity (IC₅₀ = 11.9 ± 1.5 μg/ml) towards RAW 264.7 cells than the original extract (IC₅₀ = 39.5 ± 4.1 μg/ml), and the saponin-containing fraction derived from it (IC₅₀ = 33.7 ± 6.2 μg/ml).     

Steroidal saponins from the leaves of Beaucarnea recurvata

Thirteen steroidal saponins were isolated from the leaves of Beaucarnea recurvata Lem. Their structures were established using one- and two-dimensional NMR spectroscopy and mass spectrometry. Six of them were identified as: 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25R)-furosta-5,20(22)-diene-23-one-1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 4)-6-O-acetyl-β-d-glucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, and 24-O-β-d-glucopyranosyl (25R)-spirost-5-ene-1β,3β,24-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside. The chemotaxonomic classification of B. recurvata in the family Ruscaceae was discussed.     

Differences in the floral anthocyanin content of violet–blue flowers of Vinca minor L. and V. major L. (Apocynaceae)

Two novel delphinidin 3-(tri or di)-glycoside-7-glycosides were isolated from the violet–blue flowers of Vinca minor L. and V. major L. (Family: Apocynaceae), and determined to be delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-(2^G-xylosylrobinobioside)-7-rhamnoside] as major floral anthocyanin of V. minor and delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-robinobioside-7-rhamnoside] as major floral anthocyanin of V. major by chemical and spectroscopic methods. In addition, chlorogenic acid and kaempferol 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= kaempferol 3-robinobioside-7-rhamnoside (robinin)] were identified in these flowers. In this paper, the relation between the structure of floral anthocyanins and classification of Vinca species was discussed.     

Cycloartane-type glycosides from Astragalus amblolepis

Five cycloartane-type triterpene glycosides were isolated from the methanol extract of the roots of Astragalus amblolepis Fischer along with one known saponin, 3-O-β-D-xylopyranosyl-16-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane. Structures of the compounds were established as 3-O-β-D-xylopyranosyl-25-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane, 3-O-[β-D-glucuronopyranosyl-(1 → 2)-β-D-xylopyranosyl]-25-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane, 3-O-β-D-xylopyranosyl-24,25-di-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane, 6-O-α-L-rhamnopyranosyl-16,24-di-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane, 6-O-α-L-rhamnopyranosyl-16,25-di-O-β-D-glucopyranosyl-3β,6α,16β,24(S),25-pentahydroxy-cycloartane by using 1D and 2D-NMR techniques and mass spectrometry. To the best of our knowledge, the glucuronic acid moiety in cycloartanes is reported for the first time.     

Phenolic glycosides from Cucumis melo var. inodorus seeds

A new phenolic glycoside (E)-4-hydroxycinnamyl alcohol 4-O-(2′-O-β-d-apiofuranosyl)(1″ → 2′)-β-d-glucopyranoside (1) was isolated and identified from Cucumis melo seeds together with benzyl O-β-d-glucopyranoside (2), 3,29-O-dibenzoylmultiflor-8-en-3α,7β,29-triol (3) and 3-O-p-amino-benzoyl-29-O-benzoylmultiflor-8-en-3α,7β,29-triol (4). Their structures were elucidated by extensive NMR experiments including ¹H–¹H (COSY, TOCSY, ROESY) and ¹H–¹³C (HSQC and HMBC) spectroscopy and chemical evidence. The multiflorane triterpene esters were identified as new melon constituents.