Oxylipins from Dracontium loretense.

Four novel oxylipins (1-4) were isolated from the n-butanol extract of the corms of Dracontium loretense. Their structures were assigned by 1D and 2D NMR analyses and electrospray ionization multistage ion trap mass spectrometry (ESI-ITMS(n)) data. Relative configurations were assigned on the basis of combined analysis of homonuclear and heteronuclear (2,3)J couplings, along with ROE data. Oxylipin 2 exhibited an immunostimulatory effect on human PBMC proliferation.

Steroidal glycosides from the underground parts of Helleborus caucasicus.

Four polyhydroxylated and polyunsaturated furostanol glycosides (1-4), named caucasicosides A (1), B (2), C (3) and D (4), were isolated from the MeOH extract of the underground parts of Helleborus caucasicus, along with four spirostanol derivatives, a furostanol glycoside, a furospirostanol glycoside, 20-hydroxyecdysone and the bufadienolides hellebrigenin and deglucohellebrin. The structures of 1-4 were elucidated as furosta-5,20(22),25(27)-triene-1beta,3beta,11alpha,26-tetrol 26-O-beta-D-glucopyranoside (1), 26-O-beta-D-glucopyranosylfurosta-5,20(22),25(27)-triene-1beta,3beta,11alpha,26-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (2), 26-O-beta-d-glucopyranosyl-22alpha-methoxyfurosta-5,25(27)-diene-1beta,3beta,11alpha,26-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (3), 26-O-beta-D-glucopyranosylfurosta-5,20(22),25(27)-triene-1beta,3beta,26-triol 3-O-beta-D-xylopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-4-O-sulfo-alpha-L-arabinopyranoside (4). Structure elucidation was accomplished through the extensive use of 1D- and 2D NMR experiments including 1H-1H (COSY, 1D-TOCSY) and 1H-13C (HSQC, HMBC) spectroscopy along with ESI-MS and HR-ESI-MS. The aglycones of 1-4 have never been reported before.

Determination of phenolic compounds in Yucca gloriosa bark and root by LC-MS/MS.

On the basis of the biological activities shown by yuccaols and gloriosaols from Yucca schidigera and Yucca gloriosa, the content of yuccaols and gloriosaols in two different parts of Y. gloriosa (roots and bark), was determined for each single compound, and compared with phenolic determination in Y. schidigera bark, concluding that Y. gloriosa bark and roots are rich sources of phenolic derivatives structurally related to resveratrol. LC/ESIMS (liquid chromatography coupled to electrospray mass spectrometry) qualitative and an LC/ESIMS/MS (liquid chromatography coupled to tandem electrospray mass spectrometry) quantitative studies of the phenolic fraction of Y. gloriosa were performed. LC/ESIMS/MS multiple reaction monitoring (MRM) method previously described for yuccaols in Y. schidigera was applied and optimised for separation and determination of gloriosaols and yuccaols in Y. gloriosa. Due to the sensitivity and the repeatability of the assay, we suggest this method as suitable for industrial quality control of raw materials and final products.

Flavonoids and isoflavonoids from Gynerium sagittatum.

Four flavonoids namely (2R,3R)-2,3-trans-7,4'-dimethoxydihydroflavonol, (2R,3S,4S)-2,3-trans-3,4-cis-7,4'-dimethoxy-3,4-flavandiol, 6-hydroxy-7,4'-dimethoxyflavone, 6,7,4'-trimethoxyflavone, along with the known isoflavonoids ferreirin, dihydrocajanin, dalbergioidin, dihydrobiochanin A and biochanin A and other 11 known compounds were isolated from the roots of Gynerium sagittatum. The structural characterization of these compounds was carried out via one- and two-dimensional NMR experiments in combination with ESI-MS. Finally a quantitative analysis of the isoflavones of the methanolic extract was performed by LC-ESI-MS. The high quantity of isoflavonoids found in G. sagittatum makes this plant a good natural source of isoflavonoids.

Sesquiterpene coumarins from Ferula szowitsiana and in vitro antileishmanial activity of 7-prenyloxycoumarins against promastigotes.

Two new sesquiterpene coumarins, named szowitsiacoumarin A (1) and szowitsiacoumarin B (2), and a phenylpropanoid derivative, 2-epihelmanticine (3), together with nine known compounds, auraptene (4), umbelliprenin (5), galbanic acid (6), methyl galbanate (7), farnesiferol B (8), farnesiferol C (9), persicasulfide A (10), beta-sitosterol and stigmasterol were isolated from the roots of Ferula szowitsiana. The structures of these compounds were elucidated by extensive spectroscopic methods including 1D-((1)H and (13)C) and 2D-NMR experiments (DQF-COSY, HSQC, HMBC, and ROESY) as well as HR-MALDI-MS analysis. Since the configuration of 2-epihelmanticine was previously only partly determined, a relative configurational analysis of its four stereocenters was carried out on the basis of the recently reported J-based method. The inhibiting activity of prenylated coumarins, auraptene (4) and umbelliprenin (5), in addition to galbanic acid (6), as major component, and of the Me(2)CO extract of Ferula szowitsiana (Apiaceae) roots has been evaluated against promastigotes of Leishmania major. Umbelliprenin and auraptene showed significant activity with IC(50) values of 4.9microg/ml (13.3microM) and 5.1microg/ml (17.1microM) after 48h incubation, respectively.

Yucca gloriosa: a source of phenolic derivatives with strong antioxidant activity.

On the basis of the biological activities exhibited by the phenolic constituents of Yucca schidigera, the antioxidant activity of the methanol extract of Yucca gloriosa roots was evaluated in the TEAC assay. The strong activity exerted by this extract prompted investigation of its phenolic constituents, yielding three new phenolic derivatives, gloriosaols C, D, and E, along with gloriosaols A and B previously isolated from Y. gloriosa roots and yuccaols C-E isolated from Y. schidigera. ESIMS and NMR data of gloriosaols C-E closely resembled those reported for gloriosaols A and B, two diasteroisomers characterized by unusual spirostructures. Careful inspection of ROESY spectra revealed that gloriosaols C-E are diastereoisomers of gloriosaols A and B. A possible assignment of the relative configuration of gloriosaols C-E, derived according to an integrated NMR-quantum mechanical (QM) approach, which was already applied to the determination of the stereostructures of gloriosaols A and B, is also proposed. Gloriosaols A-E exhibited potent antioxidant activity measured by the TEAC assay, showing the potential use of Y. gloriosa as a source of antioxidant principles.

Catechin derivatives in Jatropha macrantha stems: characterisation and LC/ESI/MS/MS quali-quantitative analysis.

A phytochemical investigation on methanol extract of stems of Jatropha macrantha led to the isolation of catechin, catechin-7-O-beta-glucopyranoside and proanthocyanidin B-3 along with other catechin polymers. Their structures were established by NMR and ESI/MS experiments. Additionally, an LC/ESI/MS qualitative study and an LC/ESI/MS/MS quantitative study of the phenolic fraction of J. macrantha stems were performed. Combination of high performance liquid chromatography (HPLC) (DAD) with positive electrospray ionisation (ESI) and tandem mass spectrometry (MS/MS) performed with Ion Trap analyser permitted to have qualitative data on catechin derivatives: several other proanthocyanidins were detected. A mixture of proanthocyanidin polymers was characterised by direct introduction ESI-MS analysis. An LC/ESI/MS/MS method was developed and validated for separation and quantification of catechin, catechin-7-O-beta-glucopyranoside and proanthocyanidin B-3. Due to the sensitivity and the repeatability of the assay, we suggest this method as suitable for industrial quality control of raw materials and final products. Quantitative analyses results confirmed that compounds 1-3 are major compounds of the plant and, in particular, proanthocyanidin B-3 appears to be the most abundant.

Advances in the universal NMR database approach. 2'-substituted taxanes as probes for an improved protocol of diastereomeric differentiation.

[structure: see text] The configuration of the alpha-substituted alpha-hydroxy-beta-aminoester moiety in a series of 2'-substituted taxanes was analyzed according to the recently proposed Universal NMR Database (UDB) approach. A critical analysis of the results showed that modifications regarding chemical shift adjustment (so as to render the shifts virtually connectivity independent) were necessary to get consistent stereoassignments in this set of compounds. On this basis, a modified UDB-based strategy, especially tailored to the configurational assignment of densely substituted diastereomeric fragments, is proposed.

Quantum mechanical calculations of NMR J coupling values in the determination of relative configuration in organic compounds.

[structure: see text] An approach relying on quantum mechanical calculations of proton-proton and proton-carbon J coupling values is proposed as a tool for assigning the relative configuration on chiral organic compounds. The method is suitable for carbon frameworks containing several adjacent stereogenic centers and may allow significant advances in the extensive use of spin-spin couplings in structural elucidation.

Phenolic compounds from Hypericum calycinum and their antioxidant activity.

From the MeOH extract of Hypericum calycinum, two caffeoylquinic acid derivatives, butyl chlorogenate (1), and chlorogenic acid (2), seven flavonoids, quercetin (3), quercitrin (4), hyperoside (5), isoquercitrin (6), miquelianin (7), rutin (8) and I3,II8-biapigenin (9) and two flavanols, (+)-catechin (10) and (-)-epicatechin (11) were isolated. Identification of the isolates was carried out by spectroscopic analysis including 1D and 2D NMR experiments as well as mass spectrometry. Free radical scavenging activities of the isolated compounds were determined in in-vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging models. The compounds showed strong DPPH and moderate NO scavenging activities in a concentration dependent manner. (+)-Catechin and (-)-epicatechin were found to be the most active compounds with IC50 values of 4.16 and 4.67 microM for DPPH and 190 and 170 microM for NO scavenging activities, respectively.

Characterization of flavonoid and naphthopyranone derivatives from Eriocaulon ligulatum using liquid chromatography tandem mass spectrometry.

Liquid chromatography-electrospray ionization multistage ion trap mass spectrometry (LC-ESI-IT-MS(n)) was used to analyze the secondary metabolites in the methanol extract of the capitulae of Eriocaulon ligulatum. The major components were mono- and diglycosides of flavonoids and naphthopyranones. Eleven compounds, including four new flavonol glycosides, were identified based on their fragmentation patterns in MS experiments and on NMR analysis of the isolated compounds. The described data may contribute to a better understanding of the taxonomic classification of the Eriocaulaceae family.

Polyisoprenylated benzophenones and an unusual polyisoprenylated tetracyclic xanthone from the fruits of Garcinia cambogia.

In light of the wide range of biological activities of garcinol and with the aim of exploring some of them, we carried out its isolation from the fruits of Garcinia cambogia L. (Guttiferae). Surprisingly, the fruits were also found to contain guttiferones I, J, and K, compounds never reported in G. cambogia, along with three new compounds, namely, guttiferone M (1), guttiferone N (2), and the oxidized derivative of guttiferone K (6). Oxy-guttiferone K (6) is the first example of tetracyclic xanthone derived from the oxidation of a polyisoprenylated benzophenone from natural source. The natural formation of oxy-guttiferone K is in agreement with the previously described cyclization of garcinol by DPPH.

Sulfated triterpene derivatives from Fagonia arabica.

Two new sulfated triterpenes (1, 6) and four new sulfated triterpene glycosides (2-5) have been isolated from the aerial parts of Fagonia arabica. Their structures were established by spectroscopic data analysis. Compounds 1/2 and 3/4 are sulfated derivatives of the rare sapogenins 3beta,27-dihydroxyolean-12-en-28-oic acid and 3beta,27-dihydroxyurs-12-en-28-oic acid, respectively. Compound 5 is an unusual disulfated oleanene derivative characterized by the occurrence of a 13,18-double bond, while compound 6 is the first reported naturally occurring saturated and sulfated pentacyclic triterpene of the taraxastane series with a C-20,28 lactone unit.

NMR structure of the (+)-CPI-indole/d(GACTAATTGAC)-d(GTCAATTAGTC) covalent complex.

We report the NMR solution structure of (+)-CPI-indole (CPI, 1,2,8,8a-tetrahydrocyclopropa[c]pyrrolo[3,2-e]indol-4(5H)-one), an agent belonging to the CC-1065/duocarmycin family of antitumor compounds. This (+)-CPI-indole structure is covalently bound to d(G(1)ACTAATTGTC(11))-d(G(12)TCAATTAGTC(22)), a synthetic DNA duplex containing a high-affinity binding site. The three-dimensional structure has been determined by several cycles of restrained molecular dynamics calculations with a total of 563 NMR-derived constraints, both in vacuo and by using the generalized Born solvent continuum model. In-depth analysis of the structure of this ligand-DNA complex led to a detailed knowledge of the bound state conformation of the CPI-indole, the most simplified agent related to CC-1065 and duocarmycins, the parent members of a family of extremely potent antitumor compounds. Comparison of the CPI-indole bound conformation with those previously found for (+)-duocarmycin SA (DSA), its unnatural enantiomer (-)-DSA, and the demethoxylated analogue (+)-DSI in their DNA complexes provided additional evidence of the tight correlation between the catalytic effect exerted by DNA on the alkylation reaction and the extent of angular twist between the two planar heteroaromatic subunits of these agents. Additionally, comparison of the structural features of the DNA-bound state of a "naked" ligand, such as CPI-indole, with those of various other duocarmycin agents provided useful information for the interpretation of the observed effects on chemical reactivity of the different substitution patterns at the hemispheres of these types of complex.

Tolaasins A--E, five new lipodepsipeptides produced by Pseudomonas tolaasii.

Pseudomonas tolaasii, the causal organism of brown blotch disease of Agaricus bisporus and of the yellowing of Pleurotus ostreatus, was shown to produce in culture tolaasin I (1), tolaasin II (2), and five other minor metabolites, tolaasins A, B, C, D, and E (3-7). These compounds were demonstrated to be important in the development of the disease symptoms. This paper reports on the structural elucidation, based essentially on NMR studies and MS spectra, and biological activity of the above lipodepsipeptides (3-7). All the above analogues showed differences in the peptide moiety, as observed in other lipodepsipeptides of bacterial origin, and maintained the beta-hydroxyoctanoyl phi chain at the N-terminus, except tolaasin A, in which the acyl moiety was a gamma-carboxybutanoyl phi moiety. Among the target microorganisms used (fungi, yeast, and bacteria) the Gram-positive bacteria were the most sensitive, although the antimicrobial activity appeared to be correlated to the structural modification in the different analogues. The structure-activity relationships of these toxins are discussed.