Quantitative determination of the major saponin mixture bacoside A in Bacopa monnieri by HPLC

Bacoside A, the putative bioactive component of the Indian medicinal plant Bacopa monnieri, was found to be a mixture of saponins with bacoside A3 (1), bacopaside II (2), jujubogenin isomer of bacopasaponin C (3) and bacopasaponin C (4) as major constituents. An HPLC method together with an optimised extraction procedure was developed for the estimation of 1-4 in B. monnieri to enable standardisation of the latter. Concentration ranges of the analytes in samples of B. monnieri collected from different regions of India were 0.14-0.85% (w/w) (1), 0.12-0.69% (2), 0.05-0.72% (3) and 0.05-0.44% (4). The importance of using bacoside A, with known concentrations of 1-4, as a reference standard for the routine analysis of B. monnieri is highlighted. Two common flavonoids, luteolin and apigenin, were present in all samples of B. monnieri.     

Triterpenoid glycosides from Bacopa monnieri

Two triterpenoid glycosides have been isolated along with 10 known saponins from Bacopa monnieri. Structures of the compounds have been elucidated as 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl] jujubogenin (1) and 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl] pseudojujubogenin (2) by high resolution NMR spectral data and chemical correlations. Further, the chemical compositions of bacosides A and B have been delineated.     

Effects of cucurbitacins on cell morphology are associated with sensitization of renal carcinoma cells to TRAIL-induced apoptosis

Cucurbitacins B and D were among the compounds identified as sensitizers of cancer cells to TRAIL-mediated apoptosis in a high-throughput screen. Therefore a series of cucurbitacins was further investigated for TRAIL sensitization and possible mechanisms of action. A total of six cucurbitacins promoted TRAIL-induced apoptosis (B, I, E, C, D, and K) and one (P) was inactive. Sensitization of renal adenocarcinoma cells to TRAIL was apparent after as little as 1–4 h pretreatment and did not require continued presence of cucurbitacin. Active cucurbitacins induced caspase-8 activation only after subsequent TRAIL addition and caspase activation was required for apoptosis suggesting amplified proximal signaling from TRAIL death receptors. Cucurbitacin-sensitized TRAIL-induced cytotoxicity was inhibited by N-acetyl cysteine. Structure–activity relationship analysis in comparison to published studies suggests that TRAIL-sensitizing and general cytotoxic activities of cucurbitacins may be decoupled. Cucurbitacins are reported to be inhibitors of STAT3 activation. However, their TRAIL-sensitizing activity is STAT3-independent. Treatment of renal carcinoma cells with active cucurbitacins produced rapid and dramatic changes in cell morphology and cytoskeletal organization (also prevented by NAC). Therefore, cucurbitacins may be useful as tools for investigating the molecular mechanism(s) of action of TRAIL sensitizers, particularly with regard to temporal aspects of sensitization and modulation of TRAIL signaling by cell morphology, and could form the basis for future therapeutic development in combination with TRAIL death receptor agonists.     

Anti-adipogenic chromone glycosides from Cnidium monnieri fruits in 3T3-L1 cells

Seven new chromone glycosides, monnierisides A (3), B (10), C (11), D (12), E (13), F (15) and G (16) were isolated from Cnidium. monnieri, together with ten known chromone derivatives, undulatoside A (1), cnidimol C (2), saikochromoside A (4), cnidimoside A (5), cnidimoside B (6), 2-methyl-5-hydroxy-6-(2-butenyl-3-hydroxymethyl)-7-(β-d-glucopyranosyloxy)-4H-1-benzopyran-4-one (7), cnidimol D (8), hydroxycnidimoside A (9), umtatin (14) and 6'-hydroxylangelicain (17). The structures of isolated compounds were determined on the basis of spectroscopic analysis including 1D, 2D NMR and HR-MS. Among the compounds isolated, compounds 5, 6, 9 and 10 significantly inhibited adipocyte differentiation as measured by fat accumulation in 3T3-L1 cells using Oil Red O staining.     

Ellagic acid derivatives and cytotoxic cucurbitacins from Elaeocarpus mastersii

Bioassay-guided investigation of the bark of Elaeocarpus mastersii using KB (human oral epidermoid carcinoma) cells as a monitor led to the isolation of two cucurbitacins, cucurbitacin D and cucurbitacin F as cytotoxic principles, together with two ellagic acid derivatives, 4'-O-methylellagic acid 3-(2",3"-di-O-acetyl)-alpha-L-rhamnoside (1) and 4,4'-O-dimethylellagic acid 3-(2",3"-di-O-acetyl)-alpha-L-rhamnoside (2). These compounds were evaluated against a panel of human tumor cell lines.     

Cucurbitacins from Bryonia cretica

From the roots of Bryonia cretica L. two new cucurbitacins, isocucurbitacins G (1) and H (2), along with three known cucrbitacins, cucurbitacins G (3), H (4), and J (5) were isolated. The structures of 1 and 2 were determined on the basis of 1D and 2D NMR spectroscopic analysis and X-ray crystallography. The relative stereochemistries of the side chains of 3–5 were also established by comparison of their NMR data and X-ray crystallography.     

Cuburbitacins from the cruciferae

The distribution of cucurbitacins in seeds and growing plants of Iberis umbellata L. has been investigated. The testas of 'Giant Pink', 'Purple', 'Crimson' and 'Iceberg' (Dutch) strains of Iberis umbellata contain Cucurbitacin B with traces of D and E. Seeds of 'Iceberg' (Danish) strain were exceptional in containing cucurbitacins E and I but no B, and this strain was also distinguished by larger redder seeds and by testas which were not readily separable into two layers. Cucurbitacins are rare in other crucifers but they are present in I. gibraltarica L., I. sempervirens L. and Lepidium sativum L.     

Die cucurbitacine in Bryonia alba und Bryonia dioica

The cucurbitacins in roots of Bryonia dioica and B. alba have been investigated. Both species contain the cucurbitacins E, B, I, D, J, K and L, the dihydrocucurbitacins E and B, and tetrahydrocucurbitacin I. The detection of certain cucurbitacin aglycones depends upon the date of harvest, the duration of storage and the methods used for extraction.     

An ecological cost of plant defence: attractiveness of bitter cucumber plants to natural enemies of herbivores

Plants produce defences that act directly on herbivores and indirectly via the attraction of natural enemies of herbivores. We examined the pleiotropic effects of direct chemical defence production on indirect defence employing near‐isogenic varieties of cucumber plants (Cucumis sativus) that differ qualitatively in the production of terpenoid cucurbitacins, the most bitter compounds known. In release–recapture experiments conducted in greenhouse common gardens, blind predatory mites were attracted to plants infested by herbivorous mites. Infested sweet plants (lacking cucurbitacins), however, attracted 37% more predatory mites than infested bitter plants (that produce constitutive and inducible cucurbitacins). Analysis of the headspace of plants revealed that production of cucurbitacins was genetically correlated with large increases in the qualitative and quantitative spectrum of volatile compounds produced by plants, including induced production of (E )‐β‐ocimene (3E )‐4,8‐dimethyl‐1,3,7‐nonatriene, (E,E)‐α‐farnesene, and methyl salicylate, all known to be attractants of predators. Nevertheless, plants that produced cucurbitacins were less attractive to predatory mites than plants that lacked cucurbitacins and predators were also half as fecund on these bitter plants. Thus, we provide novel evidence for an ecological trade‐off between direct and indirect plant defence. This cost of defence is mediated by the effects of cucurbitacins on predator fecundity and potentially by the production of volatile compounds that may be repellent to predators.     

Use of the cryptogein gene to stimulate the accumulation of bacopa saponins in transgenic Bacopa monnieri plants

Genetic transformation of the Indian medicinal plant, Bacopa monnieri, using a gene encoding cryptogein, a proteinaceous elicitor, via Ri and Ti plasmids, were established and induced bioproduction of bacopa saponins in crypt-transgenic plants were obtained. Transformed roots obtained with A. rhizogenes strain LBA 9402 crypt on selection medium containing kanamycin (100?mg?l(-1)) dedifferentiated forming callus and redifferentiated to roots which, spontaneously showed shoot bud induction. Ri crypt-transformed plants thus obtained showed integration and expression of rol genes as well as crypt gene. Ti crypt-transformed B. monnieri plants were established following transformation with disarmed A. tumefaciens strain harboring crypt. Transgenic plants showed significant enhancement in growth and bacopa saponin content. Bacopasaponin D (1.4-1.69?%) was maximally enhanced in transgenic plants containing crypt. In comparison to Ri-transformed plants, Ri crypt-transformed plants showed significantly (p?≤?0.05) enhanced accumulation of bacoside A(3), bacopasaponin D, bacopaside II, bacopaside III and bacopaside V. Produced transgenic lines can be used for further research on elicitation in crypt-transgenic plants as well as for large scale production of saponins. Key message The cryptogein gene, which encodes a proteinaceous elicitor is associated with increase in secondary metabolite accumulation-either alone or in addition to the increases associated with transformation by A. rhizogenes.     

Acylated iridoid glucosides from Veronica anagallis-aquatica

Three new (1-3) and four known iridoid glucosides (4-7) as well as a known phenylethanoid glycoside (8) were isolated from the aerial parts of Veronica anagallis-aquatica and their structures were determined as 6'-O-benzoyl-8-epiloganic acid named aquaticoside A (1), 6'-O-p-hydroxybenzoyl-8-epiloganic acid named aquaticoside B (2), 6'-O-benzoyl-gardoside named aquaticoside C (3), veronicoside (4), catalposide (5), verproside (6), verminoside (7) and martynoside (8) on the basis of 1D and 2D NMR spectral analysis.     

Trinorcucurbitane and cucurbitane triterpenoids from the roots of Momordica charantia

Five cucurbitacins, kuguacins A-E (1-5), together with three known analogues, 3beta,7beta,25-trihydroxycucurbita-5,(23E)-diene-19-al (6), 3beta,25-dihydroxy-5beta,19-epoxycucurbita-6,(23E)-diene (7), and momordicine I (8), were isolated from roots of Momordica charantia. Structures of 1-5 were elucidated by NMR and MS spectroscopic analysis. Among them, compounds 3-5 possess an unprecedented 25,26,27-trinorcucurbitane backbone. Compounds 3 and 5 showed moderate anti-HIV-1 activity with EC(50) values of 8.45 and 25.62 microg/ml, and exerted minimal cytotoxicity against C8166 cells (IC(50)>200 microg/ml), with a selectivity index more than 23.68 and 7.81, respectively.     

Two triterpenoids and other constituents from Petasites tricholobus

Two migrated ursane skeleton triterpenoids, one is D:B-friedoursane-3alpha,16alpha-dihydroxy-7alpha,8alpha-epoxy-5(10)-ene, named petatrichol A (1) and the other one represents a novel triterpenoid carbon framework, named petatrichol B (2), along with 10 known compounds were isolated from the rhizome of Petasites tricholobus. Their structures were elucidated on the basis of spectroscopic methods (IR, EIMS, HRMS, 1D and 2D NMR). The triterpenoids were assayed against Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Compounds 1 and 2 exhibited significant antibacterial activity against B. subtilis.     

nor-Oleanene type triterpene glycosides from the leaves of Acanthopanax japonicus

Three new (1-3) and two known (4-5) triterpene glycosides were isolated from the leaves of Acanthopanax japonicus (Araliaceae) and elucidated structurally by mass, 1D, and 2D NMR spectroscopy. All the compounds possessed a nor-oleanene triterpene skeleton as the aglycone. The structures of 1-5 were established as 28-O-alpha-L-rhamno-pyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester of 3beta-hydroxy- 30-nor-olean-12,20(29)-diene-23,28-dioic acid, designated as acanjaposide A, 3beta- hydroxy-23-oxo-30-nor-olean-12,20(29)-diene-28-oic acid, named acanjaposide B, 3beta,20alpha-dihydroxy-23-oxo-30-nor-olean-12-en-28-oic acid, named acanjaposide C, and nipponoside E, a known saponin, respectively.     

Chemistry and weak antimicrobial activities of phomopsins produced by mangrove endophytic fungus Phomopsis sp. ZSU-H76

Three metabolites named phomopsin A (1), B (2) and C (3), together with two known compounds cytosporone B (4) and C (5), were isolated from the mangrove endophytic fungus, Phomopsis sp. ZSU-H76 obtained from the South China Sea. Their structures were elucidated by spectroscopic methods, mainly by 1D and 2D NMR spectroscopic techniques. The medium-sized cyclic phenol ether based on 1 or 2 is rare in natural products. In bioassays, compounds 1, 2, and 3 had no significant antibiotic activities, but compounds 4 and 5 inhibited two fungi Candida albicans and Fusarium oxysporum with an MIC ranging from 32 to 64 microg/ml.     

Diterpenoids from Isodon enanderianus

Four ent-kauranoids, 6-epiangustifolin and enanderinanins F-H, as well as 11 known ent-kaurane diterpenoids, macrocalin B, xerophilusin A, trichorabdal A, trichorabdal B, effusin, angustifolin, longikaurin D, longikaurin F, enanderinanin B, xerophilusin G and shikokianin were isolated from the aerial parts of Isodon enanderianus. The new diterpenoids were identified as 6-epiangustifolin (11alpha-hydroxy-6alpha-methoxy-6,19-epoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide), enanderinanin F (19-acetoxy-6,20:6,11beta-diepoxy-6,7-seco-ent-kaur-16-en-15-one-1beta,7-olide), enanderinanin G (1beta,6beta,7beta-trihydroxy-19-acetoxy-16beta-methoxymethyl-7alpha,20-epoxy-ent-kaur-15-one) and enanderinanin H (6beta,7beta,14beta-trihydroxy-1alpha,11beta-acetonide-7alpha,20-epoxy-ent-kaur-16-en-15-one), respectively, on the basis of spectral data, especially by 2D NMR techniques. 6-Epiangustifolin showed significant cytotoxic activity against K562 cell.     

New cucurbitacins from Phormium tenax and Marah oreganus

Cucurbitacins I and D and two new cucurbitacins, isocucurbitacin D and 3-epi-isocucurbitacin D, were isolated from Phormium tenax. A new cucurbitacin, dihydroisocucurbitacin B, was isolated from Marah oreganus. The acid sensitivity of the 2β-hydroxy-3-keto system found in cucurbitacin D was demonstrated.     

Polyketides from Penicillium sp. JP-1, an endophytic fungus associated with the mangrove plant Aegiceras corniculatum

Four polyketides, leptosphaerone C (1), penicillenone (2), arugosin I (3) and 9-demethyl FR-901235 (4), as well as five known compounds, bacillosporin A (5), bacillosporin C (6), sequoiamonascin D (7), sequoiatone A (8), and sequoiatone B (9) were isolated from the Penicillium sp. JP-1, an endophytic fungus isolated from Aegiceras corniculatum. Their structures were determined by spectroscopic methods, mainly by 2D NMR spectroscopic analyses. Compound 1 showed cytotoxicity against A-549 cells with an IC50 value of 1.45 microM, while compound 2 showed cytotoxicity against P388 cells with an IC50 value of 1.38 microM.     

Fuscoside E: a strong anti-inflammatory diterpene from Caribbean octocoral Eunicea fusca

The screen of 10 soft coral extracts collected from the Colombian Caribbean Sea in the TPA-induced ear edema model allowed us to identify Eunicea fusca extract among others as an interesting source of active compounds. The new diterpene, fuscoside E (1), along with the known fuscoside B (2), fuscol (3), (+)-germacrene D (4) and a mixture of six sterols (5-10), were isolated from this soft coral. Their structures were elucidated by 1D and 2D NMR spectroscopy techniques. Fuscoside E (1) absolute stereochemistry was determined by chiroptical methods. Fuscoside E (1) and B (2) showed strong anti-inflammatory in the above mentioned bioassay. Additionally, fuscoside E (1) and the sterol mixture (5-10) presented antifouling activity against bacterial strains involved in surface colonization.     

Bioactive monoterpene glycosides conjugated with gallic acid from the leaves of Eucalyptus globulus

Two monoterpene glycosides, conjugated with gallic acid [globulusin A (1) and B (2)], together with four known compounds, cypellocarpin A (3), eucaglobulin (4), cuniloside (5) and (1S, 2S, 4R)-trans-2-hydroxy-1,8-cineole beta-d-glucopyranoside (6), were isolated from hot-water extracts of the leaves of Eucalyptus globulus. The structures of compounds 1 and 2 were determined by 1D, 2D NMR and MS spectroscopic analyses. The absolute stereochemistry of 1 was determined by correlating the spectroscopic data with those of synthetic compound 6 with a known configuration. Globulusin A (1) and B (2), cypellocarpin A (3) and eucaglobulin (4), scavenged DPPH free radicals and globulusin A (1) showed a higher antioxidant activity than the other tested compounds, with an IC50 of 3.8microM. Globulusin A (1) and eucaglobulin (4) concentration-dependently suppressed inflammatory cytokine production, tumor-necrosis factor-alpha and interleukin-1beta in cultured human myeloma THP-1 cells co-stimulated with phorbol myristate acetate. These compounds also inhibited melanogenesis in cultured murine melanoma B16F1 cells, without any significant cytotoxicity. These results suggested that globulusin A (1) and eucaglobulin (4), which were isolated as antioxidants from E. globulus, also had anti-inflammatory as well as anti-melanogenesis activity.