Unexpected Novel Pheophytin Peroxides from the Leaves of Biden pilosa

Two new pheophytins, bidenphytins A ( 1 ) and B ( 2 ), with peroxide functionalities on ring E, were isolated from Biden pilosa Linn . var. radiata Sch . Bip ., a popular Taiwanese folk medicine. Also isolated were the following six known compounds: pheophytin a ( 3 ), (13²R)‐13²‐hydroxypheophytin a ( 4 ), (13²S)‐13²‐hydroxypheophytin a ( 5 ), (13²R)‐13²‐hydroxypheophytin b ( 6 ), (13²S)‐13²‐hydroxypheophytin b ( 7 ), and aristophyll‐C ( 8 ). Their structures were elucidated by spectroscopic methods (UV, IR, 1D‐ and 2D‐NMR) and by mass spectrometry (HR‐FAB‐MS). Possible biosynthetic pathways for 1 and 2 are proposed.     

叶绿素衍生物的合成及其对紫细菌原初光化学特性 的影响研究

对10个叶绿素衍生物的合成方法进行了研究,在一定的温度(43.5℃)和丙酮的协同作用下,植物脱镁叶绿素a可转换紫细菌RS601光合反应中心的细菌脱镁叶绿素,光化学活性为对照的71.4%,光化学活性的下降与替代色素的变化无对应关系,替代后降低了Bphe^-/Bphe和QA^-/QA电对之间的电子传递速率。     

Rumphellolides A-F, six new caryophyllane-related derivatives from the Formosan Gorgonian coral Rumphella antipathies

Six new caryophyllane-related natural products, including two carboxylated sesquiterpenoids, rumphellolides A (1) and B (2), and four norsesquiterpene alcohols, rumphellolides C-F (3-6), were isolated from the Formosan gorgonian coral Rumphella antipathies. The structures of the above new natural products were established on the basis of extensive spectral data analysis. Rumphellolides A (1), D (4), E (5), and F (6) showed weak antibacterial activity.     

A new alkaloid and its artificial derivative with an indazole ring from Nigella glandulifera

A new compound, nigeglanine (1), and its new artificial derivative (1a), were isolated from the seeds of Nigella glandulifera, together with a known aporphine alkaloid, fuzitine (2). Their structures were established by spectral analysis, including two-dimensional (2D)-NMR spectroscopy. Nigeglanine (1) is the third natural product determined to contain an indazole nucleus.     

Isolation and characterization of chlorophylls and xanthophylls in grass by high-speed countercurrent chromatography

To isolate chlorophyll from grass extract by means of high-speed countercurrent chromatography, a solvent system composed of n-hexane–dichloromethane–ethanol–water 4:2:6:2 (v/v/v/v) was applied. The isolation of chlorophylls a, b, and pheophytins a, b was successfully performed from grass when dichloromethane was part of the solvent system. Comparatively, when chloroform is part of the stationary phase instead of dichloromethane, the xanthophyll separation showed better resolution compared to chlorophylls. Through the solvent system, we could demonstrate the meaningful difference of polarity between dichloromethane, a polar aprotic solvent, and chloroform, a non-polar solvent. Therefore, n-hexane–dichloromethane–ethanol–water 4:2:6:2 (v/v/v/v) is adequate for chlorophylls separation because it changes the system to yield more polarity. This hypothesis supports the fact that the elution mode length was 10?hr and the extrusion mode 2?hr, whereas with chloroform the elution mode length was 7?hr and the extrusion mode 4?hr. Online high-performance liquid chromatography in conjunction with atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) was suitable to identify xanthophylls and chlorophylls fractions by means of mass spectra in positive (+) mode. Structure elucidation of chlorophylls and pheophytins was done by nuclear magnetic resonance (NMR) 1D/2D-NMR experiments.     

Determination of chlorophyll in plant samples by liquid chromatography using zinc-phthalocyanine as an internal standard

Chlorophyll analysis at high precision and accuracy is limited by the lack of suitable, commercially available internal standards for HPLC analysis. Here, the commercially available dye zinc-phthalocyanine is presented as a new internal standard to quantify chlorophylls in vegetable foods and to detect chlorophyll degradation products. The technique was applied to chlorophyll analysis of a selection of vegetable foods. Pigments were extracted with N,N-dimethylformamide from the vegetables and purified by solid phase extraction. Chlorophyll a, a', b, b', corresponding pheophytins, and zinc-phthalocyanine were separated by HPLC using a C18 reverse-phase column and fluorescence detection.     

SPECTROSCOPIC CHARACTERIZATION OF TWO FORMS OF THE D1-D2-CYTOCHROME b559 COMPLEX FROM SUGAR BEET

Two D1-D2-cytochrome b559 complex forms, called RCIIa and RCIIb, with different pigment stoichi-ometry were characterized using absorption and surface-enhanced resonance Raman scattering spectroscopy and spectral gaussian deconvolution. Electronic absorption spectra of the RCIIb at 277 K showed significant differences compared to RCIIa, i.e . a strong decrease in the absorbance due to carotenoid and chlorophyll for the same amount of pheophytin. A reduced carotenoid and chlorophyll content in RCIIb was also observed in the surface-enhanced resonance Raman scattering spectra. Spectral deconvolution elicited three main absorption bands at 680, 672 and 669–670 nm, which were ascribed to P680, pheophytin and accessory chlorophyll, respectively. In addition, a minor component around 667 nm was observed in the RCIIb, most probably due to some reaction center inactivation. Calculation of the relative area under the gaussians together with pigment stoichiometry data suggest that the 680, 672 and 669–670 nm components contain, respectively, two chlorophylls, two pheophytins and four chlorophylls for the RCIIa, and two chlorophylls, two pheophytins and two chlorophylls for the RCIIb.     

Two New Triterpenoids from the Stems of Schisandra bicolor

Two new triterpenoids, schisanbilactones A and B ( 1 and 2 , resp.), and a new natural product, 1‐chloro‐3‐phenylhex‐5‐en‐3‐ol ( 3 ), as well as a known triterpenoid, kadsulactone A ( 4 ), were isolated from the stems of Schisandra bicolor. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D‐NMR techniques.     

New bioactive natural products from Coprinus micaceus

Chemical studies on the crude methanolic extract of Coprinus micaceus, collected from the Canadian Prairie region, have resulted in the isolation of two new natural products, micaceol (1), a sterol and (Z,Z)-4-oxo-2,5-hetpadienedioic acid (2). Compound 2 was isolated for the first time as a natural product. Structures of these new compounds were established with the aid of extensive NMR spectroscopic studies. Compound 1 has shown anti-bacterial activity against Corynebacterium xerosis and Staphylococcus aureus, whereas compound 2 exhibited glutathione S-transferase inhibition.     

Terpenoid-related metabolites from a formosan soft coral Nephthea chabrolii

Two new sesquiterpenoidal natural products chabrolidiones A and B (1 and 2), two C(18) terpenoid-related carboxylic acids, ketochabrolic acid (3) and isoketochabrolic acid (4), and one naphthoquinone derivative chabrolonaphthoquinone C (5), along with two known compounds (+)-aristolone (6) and teuhetenone A (7) were isolated from a Formosan soft coral Nephthea chabrolii. The structures of the new metabolites were determined on the basis of extensive spectroscopic analysis and by comparison of NMR data with those of related metabolites. Metabolite 1 has been synthesized previously, but was isolated for the first time from natural sources. Cytotoxic activity of metabolites 1-3 and 5-7 against a limited panel of cancer cell lines is also described.     

Echinopsacetylenes A and B, new thiophenes from Echinops transiliensis

Two new polyacetylene thiophenes, echinopsacetylenes A and B (1 and 2), were isolated from the roots of Echinops transiliensis. The structures of 1 and 2 were elucidated on the basis of spectroscopic analyses and chemical transformations. Echinopsacetylenes A (1) is the first natural product possessing an α-terthienyl moiety covalently linked with another thiophene moiety. Echinopsacetylenes B (2) is the first natural thiophene conjugated with a fatty acid moiety. Echinopsacetylene A (1) showed toxicity against the Formosoan subterranean termite (Coptotermes formosanus).     

Sesquiterpene coumarins from the roots of Ferula sinkiangensis and Ferula teterrima

Three new natural sesquiterpene coumarins, isofeterin (1), lehmannolol (3), sinkianone (4), and one known compound, lehmannolone (2), were isolated from the roots of Ferula teterrima and Ferula sinkiangensis. Their chemical structures were established on the basis of spectroscopic analysis, including X-ray crystallography and CD spectrum measurements for determining the absolute configuration of compound 2.     

The chemical constituents of the tissue culture cells of Daphne giraldii cullus

Three compounds were isolated from the tissue culture cells of Daphne giraldii cullus,their structures were identified as daphneolone(1),S-(+)-1-(4-hydroxy-3-methoxyphenyl)-3-hydroxy-5-phenyl-1-pentanone(2),S-(+)-1-(4-methoxyphenyl)-3- hydroxy-5-phenyl-1-pentanone(3),and among them,2 was a new compound,3 was a novel natural product.     

Mössbauer spectroscopic and magnetic properties of iron/III/ pheophytins

Mössbauer spectra of /pheophytinato a/ iron/III/ chloride [Fe/Pheo-a/Cl] and /pheophytinato b/ iron/III/ chloride [Fe/Pheo-b/Cl] have revealed that the central iron/III/ ion is in a high-spin state and axially coordinated by chloride ions in solid phase. Temperature-dependent asymmetry observed for the quadrupole splitting doublet of iron/III/ pheophytins, i.e., Fe/Pheo-a/Cl and Fe/Pheo-b/Cl, is interpreted on the basis of the zero-field splitting. The structural difference between iron/III/ pheophytins and iron/III/ porphyrins is reflected in the quadrupole splitting more than in the isomer shift. Magnetic behaviour of iron/III/ pheophytins near 4.2 K is very similar to that of iron/III/ porphyrins.     

Influence of the Mn(II) and CH4 on the evolution of light induced radicals in chloroplasts

The photochemical activity of the leaves and chloroplasts of several species of plants developed in gaseous hydrocarbon environments (C_nH_2n+2) was investigated by the EPR method. The influence of different concentrations of paramagnetic ions [Mn(II), Cu(II) and VO(II), respectively] on the plants grown in dietary media containing these ions was also followed by EPR spectroscopy. The contents of paramagnetic ions, lower than 0.1%, in the nutritive solutions, are the most suitable in the biosynthesis of chlorophyll-like pigments containing paramagnetic ions in their porphyrine ring. The changes in the form, structure and photosensibility of the EPR signals corresponding to the free radicals, as well as the properties of the pheophytins containing paramagnetic ions, such as: Mn(II), Cu(II) and VO(II), were related to the photochemical synthesis in gaseous hydrocarbon environments.     

Stereochemical determination of tetrahydropyran-substituted xanthones from fungus Chaetomium murorum

Chaetoxanthone D (1), a new tetrahydropyran-substituted xanthone originated from polyketide pathway, together with the four known natural products chaetoxanthone C (2), alternariol methyl ether (3), alternariol (4) and 2,5-dimethyl-7-hydroxychromone (5) was isolated from a strain of Chaetomium murorum. The structures of these compounds were elucidated based on extensive spectroscopic analyses. The absolute configurations of 1 and 2 were determined by using quantum chemical electronic circular dichroism (ECD) calculations.     

Chlorinated briarane-type diterpenoids from the gorgonian coral Ellisella robusta (Ellisellidae)

Four chlorinated metabolites featuring briarane carbon skeletons have been isolated from the gorgonian coral Ellisella robusta, which was collected off the coast of southern Taiwan: two new natural products, robustolides D (1) and E (2), and two known metabolites, robustolides F (3) and G (4). The structures of metabolites 1–4 were determined by spectroscopic methods, using 1D and 2D NMR in particular. The structures and absolute stereochemistry of robustolides D (1), F (3), and G (4) were directly established by X-ray diffraction analysis. Robustolide D (1) is the first metabolite of briarane-related natural products found to possess two halogen atoms.     

Structure elucidation of three diphenyl ether derivatives from the mangrove endophytic fungus SBE‐14 from the South China Sea

Two new natural products, tenelate A ( 1 ) and B ( 2 ), together with the known compound, tenellic acid C ( 3 ), were isolated from the mangrove endophytic fungus Talaromyces sp. (SBE‐14), from the South China Sea. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR techniques. Copyright © 2009 John Wiley & Sons, Ltd.     

A new glycoside from the leaves of Neoalsomitra integrifoliola

A new ionone glycoside （6R,9R）-blumenyl α-L-rhamnopyranosyl-（1 → 6）-β-D-gluco-pyranoside （1）, together with a new natural product 2-methoxyl-4-trans-pmpenyl-phenol α-L-rhamnopyranosyl-（1 → 6）-β-D-glucopyranoside （2）, was isolated from the leaves ofNeoalsomitra integrifoliola. Their structures were elucidated by chemical and spectral analysis. Compound 1 showed weak anti-inflammatory and low-level antioxidant activities.     

New constituents from the heartwood of Picea morrisonicola HAYATA

Three new constituents, including a p-menthane type monoterpene, trans-p-menthane-7,8,9-triol (1), an aromatic, 2,6-dihydroxy-3,4-dimethylbenzoic acid methyl ester (2), and a lignan, (+)-morrisonicolanin (3), were isolated from the low polar layer of heartwood extracts of Picea morrisonicola, and their structures were elucidated on the basis of spectroscopic analysis. Of these compounds identified, 1 was obtained as its diacetylated derivative 1a, and 2 was the chemical entity first isolated from a natural source.