Gas-phase intramolecular hydroxyl-amino exchange of protonated arginine and verified by the synthetic intermediate compound.

A new fragmentation process was proposed to interpret the characteristic product ion at m/z 130 of protonated arginine. The α-amino group was dissociated from protonated arginine and then combined with the (M + H-NH ) fragment to form an ion-neutral complex which further generated a hydroxyl-amino exchange intermediate compound through an ion-molecule reaction. This intermediate compound was synthesized from argininamide through a diazo reaction, and then the reaction mixture was analyzed using liquid chromatography combined with mass spectrometry (LC-MS).

Lanostane-type C triterpenoid derivatives from the fruiting bodies of cultivated Fomitopsis palustris.

Fifteen undescribed and five known lanostane-type C triterpenoid derivatives were isolated from the aqueous EtOH extract of the fruiting bodies of cultivated Fomitopsis palustris. Their structures were identified from the spectroscopic data and chemical degradation studies. The structures of palustrisoic acids A and H were confirmed by X-ray crystallography.

Analysis of oxovanadium(IV) complexes using electrospray mass spectrometry: Molecular ion formed by loss of an electron, and its product ions trapping oxygen.

Rationale: In addition to their biological properties, oxovanadium complexes have been widely applied as catalysts because of their excellent catalytic-oxidation capability. Recently, monometallic oxovanadium(IV) complexes have been used as catalysts in the electrophilic trifluoromethylation of silyl ketene imines. The study of catalysts can contribute to an understanding of the reaction mechanism.

Antibacterial Activity and Membrane-Disruptive Mechanism of 3-p-trans-Coumaroyl-2-hydroxyquinic Acid, a Novel Phenolic Compound from Pine Needles of Cedrus deodara, against Staphylococcus aureus.

Recently, we reported that a novel phenolic compound isolated from Cedrus deodara, 3-p-trans-coumaroyl-2-hydroxyquinic acid (CHQA), exhibits a potent antioxidant activity. The present study aimed to evaluate the antibacterial activity of CHQA against eleven food-borne pathogens and to elucidate its mechanism of action against Staphylococcus aureus. The results from minimum inhibitory concentration (MIC) determinations showed that CHQA exhibited moderate inhibitory effects on all of the tested pathogens with MIC values ranging from 2.

Nitrogen-containing dihydro-β-agarofuran derivatives from Tripterygium wilfordii.

Thunder god vine, the dried roots of Tripterygium wilfordii, is a widely used traditional Chinese medicine. More than 200 bioactive complex natural products have been isolated from this herb. Inspired by the diversity of chemical structures and bioactivities of the components of this herb, the investigation to mine new chemical entities as potential drug leads led to the identification of 36 nitrogen-containing compounds.

A new triterpene and an antiarrhythmic liriodendrin from Pittosporum brevicalyx.

A new triterpene, 21-O-senecioyl-R(1)-barrigenol (1) and 13 known compounds were isolated from the ethanol extracts of the leaves and bark of Pittosporum brevicalyx (Oliv.) Gagnep. Their structures were elucidated based on spectral data.

Analysis of sesterterpenoids from Aspergillus terreus using ESI-QTOF and ESI-IT.

Introduction: Biosynthesis of terretonin was studied due to the interesting skeleton of this series of sesterterpenoids. Very recently, López-Gresa reported two new sesterterpenoids (terretonins E and F) which are inhibitors of the mammalian mitochondrial respiratory chain. Mass spectrometry (MS), especially tandem mass spectrometry, has been one of the most important physicochemical methods for the identification of trace natural products due to it rapidity, sensitivity and low levels of sample consumption.

Analysis of caffeic acid derivatives from Osmanthus yunnanensis using electrospray ionization quadrupole time-of-flight mass spectrometry.

A series of six caffeic acid derivatives (1-6) in Osmanthus yunnanensis were investigated by electrospray quadrupole time-of-flight tandem mass spectrometry (ESI-QToF-MS/MS) in both negative- and positive-ion modes. High-quality MS/MS spectra of [M + H](+) are generated from high-abundance protonated parent ions obtained by addition of ammonium chloride to the solutions. Fragmentation mechanisms of [M - H](-) and [M + H](+) precursor ions were proposed and elemental compositions of most of the product ions were confirmed on the basis of the high-resolution ESI-collision-induced dissociation (CID)- MS/MS spectra.

Analysis of epipolythiodioxopiperazines in fungus Chaetomium cochliodes using HPLC-ESI-MS/MS/MS.

A series of epipolythiodioxopiperazines in the fungus Chaetomium cochliodes was investigated using reversed-phase liquid chromatography with diode array detection and electrospray quadrupole time-of-flight-type tandem mass spectrometry in the positive ion mode. The fragmentation of protonated molecular ions including low-abundance parent ions, [M+H]+ for five known epipolythiodioxopiperazines, dethiotetra(methylthio)chetomin, chaetocochins A-C, and chetomin, was carried out using low-energy collision-induced electrospray ionization tandem spectrometry. It was found that McLafferty rearrangements occurred in the CID processes and produced a complementary pair of characteristic fragment ions containing piperazine rings (fused and unfused), especially to determine the number of S atoms on each ring.

Three new limonoids from Cipadessa cinerascens.

Three new limonoids, cipadesins D--F (1--3), together with 8,15-dihydroxy-13E-labdane, beta-sitosterol and beta-daucosterol, were isolated from the leaves and bark of Cipadessa cinerascens. Their structures were elucidated by spectral evidence. X-Ray crystallographic analysis confirmed the structure of 1.

Electrospray tandem mass spectrometry of epipolythiodioxopiperazines.

Low-energy collision-induced electrospray ionization tandem mass spectrometry ESI-CID-MS/MS (in the positive ion mode) was used for the structural characterization of a series of five representative epioplythiodioxopipreazines: dethiotetra(methylthio)chemotin, chaetocochins A, B and C, and chemotin isolated from the fungus Chaetomium cochliodes. The fragmentation pathways were elucidated by ESI-IT-MS(n). The elemental compositions of most of the product ions were confirmed by low-energy ESI-CID-QTOF-MS/MS analyses.

Chiral decalins: preparation from oleanolic acid and application in the synthesis of (-)-9-epi-ambrox.

A novel and versatile process was developed to prepare the trans-decalins Delta9(11)-3beta-acetoxysclareolide (2) and Delta9(11)-3beta-acetoxy-8-epi-sclareolide (3), respectively, with 4a-methoxycarbonyl-2,7,7-trimethyl-1-oxo-cis-decalin-2-ene (4) and its C-3 hydroxyl derivative 5 from oleanolic acid (3beta-hydroxyolean-12-en-28-oic acid, 1). Three key steps were (a) introduction of the AcO-12 group and the C-9,C-11 double bond at ring C of methyl 3beta-acetoxyolean-12-en-28-oate (8) to afford the diene, methyl 3,12-diacetoxyolean-9(11),12-dien-28-oate (11); (b) photolytic cleavage of the C-8,C-14 bond in the diene to give an acetoxy-substituted triene 14; and (c) oxidative cleavage of the triene or its hydrolyzed alpha,beta-unsaturated ketone product with m-CPBA/TsOH to give the cis- and trans-decalins 2-5. Delata9(11)-3beta-Acetoxysclareolide (2) was stereospecifically reduced to give 3beta-acetoxy-9-epi-sclareolide (23), from which (-)-9-epi-ambrox (7) was synthesized.

Steryl esters and phenylethanol esters from Syringa komarowii.

Three new steryl esters and a new phenylethanol ester, together with 22 known compounds were isolated from the aqueous ethanolic extract of the whole plants of Syringa komarowii. The new compounds were elucidated as stigmastane-3beta,6alpha-diol 3-O-tetradecanoate (1), stigmastane-3beta,6alpha-diol 3-O-palmitate (2), stigmastane-3beta,6alpha-diol 3-O-stearate (3), and 2-(4-hydroxyphenyl)-ethyl dotriacontanoate (4) on the basis of extensive spectral data and chemical evidences.

Novel cadinane and norcadinane sesquiterpenes and a new propanoate from Goldfussia psilostachys.

Three new compounds, goldfussins A (1) and B (2) and goldfussinol (3), and sixteen known compounds were isolated from the ethanolic extract of the whole plants of Goldfussia psilostachys. The structures of the new compounds were elucidated as a novel cadinane sesquiterpene, 1,8-dimethyl-5-hydroxymethyl-9-oxo-6,7,8,9-tetrahydronaphtho[2,1- b]furan (1), a novel norcadinane sesquiterpene, 4-acetyl-3-hydroxy-1-hydroxymethyl-6-methyl-5-oxo-5,6,7,8-tetrahydronaphthalene (2) and methyl 3-hydroxy-2-(3,5-dimethoxy-4-hydroxyphenyl)-propanoate (3) on the basis of spectral data.

Phenolic and triterpene glycosides from the stems of Ilex litseaefolia.

Chemical investigation on the stems of Ilex litseaefolia afforded four new phenolic glycosides, litseaefolosides A-D (1-4), and two new triterpene glycosides, spathodic acid 28-O-beta-d-glucopyranoside (5) and (20S)-niga-ichigoside F1 (6), along with 28 known compounds. The structures of 1-6 were determined on the basis of chemical and spectroscopic evidence. Litseaefoloside C (3) showed inhibitory activities in vitro for alpha-glucosidase and lipase with IC(50) values of 34.

Cipadesins A-C: novel tetranortriterpenoids from Cipadessa cinerascens.

[structure: see text] Three novel tetranortriterpenoids, cipadesins A-C (1-3), were isolated from the aerial parts of Cipadessa cinerascens. They possess a novel carbon skeleton, in which rings A and C were joined via C-10 and C-11. Their structures were elucidated by spectral evidence.

Four new benzofurans from seeds of Styrax perkinsiae.

Four new benzofurans trans-5-(3-hydroxypropyl)-7-methoxy-2-[2,3-dihydro-3-hydroxymethyl-7-methoxy-2-(3-methoxy-4-hydroxyphenyl)-benzofuran-5-yl]benzofuran (1), (E)-5-(2-formylvinyl)-7-methoxy-2-(3,4-methylenedioxyphenyl)benzofuran (2), 5-(3-butanoyloxypropyl)-7-methoxy-2-(3,4-methylenedioxyphenyl)benzofuran (3), and 5-(3-hydroxypropyl)-7-hydroxy-2-(3,4-methylenedioxyphenyl) benzofuran (4) were isolated from the seeds of Styrax perkinsiae, together with egonol (5), demethoxyegonol (6), egonol acetate (7), demethoxyegonol acetate (8), egonol glucoside (9), egonol gentiobioside (10), egonol gentiotrioside (11), beta-sitosterol (12), and beta-daucosterol (13). Their structures were established by spectroscopic and chemical methods. Compounds 1 and 4 exhibited cytotoxic activity in vitro using two breast cancer cell lines MCF-7 and MDA-MB-231.

Sesterterpenoids, terretonins A-D, and an alkaloid, asterrelenin, from Aspergillus terreus.

Four new sesterterpenoids, terretonins A-D (1-4), and a new alkaloid, asterrelenin (5), together with five known compounds, were isolated from the ethyl acetate extract of a solid-state fermented culture of Aspergillus terreus. Their structures were elucidated on the basis of spectroscopic analysis. The structures of 1, 2, and 5 were confirmed by X-ray crystallographic analysis.

A new glucoceramide from the watermelon Begonia, Pellionia repens.

A new glucoceramide named pellioniareside (1) was isolated from the aqueous ethanolic extract of whole plants of Pellionia repens, together with lupeol (2), uracil (3), (22E,20S,24R)-5alpha,8alpha-epidioxyergosta-6,22-dien-3-beta-ol (4), and daucosterol (5). The structure and relative configurations of pellioniareside were identified as (2S,3S,4R,6E,8E)-1-O-beta-D-glucopyranosyl-2-[(2 R)-2-hydroxytetracosanoylamino]-1,3,4-octadecanetriol-6,8-diene by analysis of spectral data and by chemical evidence.

Two diterpenes and three diterpene glucosides from Phlogacanthus curviflorus.

Two new diterpene lactones, phlogacantholides B (1) and C (2), and three new diterpene lactone glucosides, phlogacanthosides A (3), B (4), and C (5), together with lupeol, beta-sitosterol, betulin, beta-daucosterol, (+)-syringaresinol, and (+)-syringaresinol-4-O-beta-D-glucopyranoside, were isolated from the roots of Phlogacanthus curviflorus. Their structures were elucidated by chemical and spectroscopic evidence. The structure, including the relative configuration of phlogacantholide B (1), was confirmed by X-ray crystallographic analysis of its diacetate (6).