Two diterpene alcohols from Croton sublyratus

The isolation and structural elucidation of two diterpene alcohols from Croton sublyratus are described. These compounds are ent-3α-hydroxy-13-epimanool and ent-16β,17-dihydroxykaurane.     

Auriculoside,a new flavan glycoside from Acacia auriculiformis

The structural elucidation of auriculoside, a new flavan glucoside from Acacia auriculiformis, is described. This is the third report of a flavan glycoside unsubstituted in the heterocyclic ring.     

Dysobinin,a new tetranortriterpene from Dysoxylum binectariferum

Dysobinin, a new tetranortriterpene of the meliacin group showing general CNS-depressant action and mild anti-inflammatory activity was isolated from the fruits of Dysoxylum binectariferum. Alkaline hydrolysis of dysobinin gave a new diol named dysobindiol. The structural elucidation of dysobinin and dysobindiol is described.     

Two new guaiane-sesquiterpenes from the cultured lichen mycobiont of Diorygma pruinosum

Lichens and the mycobionts derived from lichen-source are believed to be a valuable source of bioactive compounds. Diorygma pruinosum is a native lichen in Vietnam. A mycobiont of Diorygma pruinosum was separated, then cultivated. Phytochemical data on this lichen and its cultured mycobionts are scarce. The present study described the isolation and structural elucidation of two new guaiane-type sesquiterpenes, namely pruinosone (1) and hydroxypruinosone (2). Their absolute chemical structures were elucidated by extensive 1D and 2D NMR analysis, high-resolution mass spectroscopy, electronic circular dichroism (ECD), and comparisons in the literatures. Compounds 1 and 2 were evaluated for alpha-glucosidase inhibition and antimicrobial activity.     

Three sesquiterpene lactones from Helianthus niveus subsp. canescens and H. argophyllus

Further investigation of the minor terpenoids in Helianthus niveus subsp. canescens and H. argophyllus afforded two known 12,8-fused sesquiterpene lactones, 3-acetylchamissonin and simsiolide as well as one new germacranolide, argophyllin C. Identification and structure elucidation of these lactones by ¹H NMR and chemical transformations are described.     

Isodidrovaltratum,ein neues valepotriat aus Valeriana vaginata

The isolation and structural elucidation of a new valepotriate, isodidrovaltrate, from Valeriana vaginata is reported.     

Microbiological Hydroxylation of Carbons 18 and 19 in 9-Oxo-13 (cis and trans)-Prostenoic Acids

dl-9-Oxo-13 (cis and trans)-prostenoic acids were converted in high yields into their 18- and 19-hydroxy derivatives by cultures of Microascus trigonosporus. The structure elucidation of the microbial products is described.     

Power functions in physiology and pharmacology

The plasma clearance curves of certain substances which are removed from the circulation by the liver with high extraction ratios are best described by a power function of the form At^?a. This is most significant both in the calculation of metabolic turnover, and in the elucidation of the function of the liver.     

Structural clarification of germacranolides from Calea species

The aerial parts of Calea pinnatifida contain a 4-glycosyloxybenzoic acid, anisic acid, tetradeca-4E,6E,12E-trien-8,10-diyn-1-ol and arucanolide. The structural elucidation of this germacranolide included comparison with neurolenin B whose stereochemistry had been defined by X-ray crystallographic analysis. The data suggest that the structures of all other known germacranolides of the genus Calea should be revised.     

13C NMR spectroscopy of Pyrrolizidine alkaloids

The ¹³C NMR spectra of nine pyrrolizidine alkaloids of the macrocyclic diester type, seven of the corresponding N-oxides and of the parent base retronecine have been recorded and the signals assigned. The 13C NMR signals were found to be sensitive to structural variation in both the diester moiety and the heterocyclic ring system, providing useful information for structural elucidation, particularly when the ¹H NMR spectra may be difficult to interpret.     

The structure of verdohemochrome and its implications for the mechanism of heme catabolism

The synthesis, purification as a tetrafluoroborate salt and structural elucidation of the verdohemochrome 2a derived from the coupled oxidation of octaethylhemochrome 1 is described. Based on elemental analyses, spectroscopic studies (visible and infrared absorption, ¹H-NMR) and fast atom bombardment mass spectrometry, the assignment of the iron(II) oxaporphyrin structure for the verdohemochrome 2a and the blue monocarbonyl species 2b, obtained upon treatment of 2a with carbon monoxide, has been accomplished. This assignment raises a number of questions regarding the iron oxidation state of intermediates in the pathway of heme catabolism both in vitro and in vivo. Furthermore, the implications of the occurrence of an iron oxaporphyrin intermediate in the pathway of heme metabolism, which is suggested by the similarity of the visible absorption spectrum of the CO species 2b with that of a new intermediate recently observed in the heme oxygenase-catalyzed degradition of heme and mesoheme, is considered.     

Prenylated benzoic acid derivatives from Piper aduncum L. and P. hostmannianum C. DC. (Piperaceae)

The bioactivity-guided fractionation of the crude extracts from leaves of Brazilian species Piper aduncum and Piper hostmannianum by means of bioautography using the fungi Cladosporium cladosporioides and C. sphaerospermum afforded prenylated methyl benzoate, chromenes, and dihydrobenzopyran derivatives as antifungal compounds. The isolation and structural elucidation of a new compound methyl 4-hydroxy-3-(2′-hydroperoxy-3′-methyl-3′-butenyl)benzoate were performed by application of chromatographic techniques and spectroscopic analyses.     

Diketopiperazines from two strains of South China Sea sponge-associated microorganisms

The paper reports the isolation and structural elucidation of seven diketopiperazines from the title microorganisms. Although all isolates are known, three of which were isolated from the actinomycetes for the first time. And this is also the first report to isolate four DKPs from the D. avara-associated microorganism.     

The major cyanogenic glycoside in thalictrum aquilegifolium

The isolation and structure elucidation of the third and major cyanogenic glycoside of T. aquilegifolium as (II) is described.     

Phosphonosphingoglycolipid,a novel sphingolipid from the viscera of Turbo cornutus

A novel lipid which contained long-chain base, fatty acid, galactose and N-methylaminoethylphosphonic acid in an equimolar was isolated from the viscera of Turbo cornutus.The methods used for the structural elucidation of this lipid were partial acid hydrolysis, alkaline hydrolysis, periodate oxidation and Smith degradation. The structure of breakdown products were mainly identified by combined gas chromatography and mass spectrometry.The structure of the novel lipid was determined to be 1-O-[6′-O-(N-methylaminoethylphosphonyl) galactopyranosyl] ceramide.Mass spectra of galactose-N-methylaminoethylphosphonate and glycerol-N-methylaminoethylphosphonate are given.     

Jacquinonic acid,an ant-repellent triterpenoid from Jacquinia pungens

The isolation and structure elucidation of jacquinonic acid, an ant-repellent triterpenoid from Jacquinia pungens, are described. This compound is a highly functionalized derivative of the oleanane skeleton, which contains both the uncommon C-13, 28 ether linkage and an α,β-unsaturated 3-keto group.     

Phytochemistry and biosynthesis of δ-lactone withanolides

Withanolides are highly oxygenated natural products. These C₂₈ steroids with ergostane-based skeletons functionalized at C-22 and C-26 form six-membered δ-lactone rings. Withanolides containing a δ-lactone side chain often occur in Solanaceae and have a variety of biological activities because of their complicated structures. Characteristic spectroscopic behaviors and biosynthesis of withanolides are conducive to their structural elucidation and “biomimetic synthesis”, respectively. However, the last review to summarize their spectroscopic features and biosynthesis was in 1996. Since then, many withanolides with novel structures have been described by their spectra with biosynthesis investigated with many bioassays. This review surveys δ-lactone withanolides and emphasizes their spectral features, configurations and biosynthetic genes. The period reviewed includes through January 2014. We also include phytochemical species.     

Chemical constituents of the stems of Zanthoxylum limonella Alston

A novel quinolone alkaloid, 4-methoxy-3-(3-methyl-2-oxobut-3-enyl)quinolin-2(1H)-one, limonellone (1), together with five known compounds has been isolated from the stems of Zanthoxylum limonella. The structural elucidation of isolated compounds was established through spectroscopic and MS analyses.     

Sequence determination of peptides by mass spectrometry: methods for combining "wet" separation techniques with mass spectrometry.

Methods are described that allow the combination of established techniques for peptide separation, paper chromatography and electrophoresis, with mass spectrometry. The development of these methods is part of an ongoing effort in the search for a methodology for the systematic utilization of mass spectrometry for the elucidation of primary structure of proteins and peptides. Peptides and amino acids are detected on chromatograms by conversion to covalent derivatives that are also suitable for mass spectrometry. The most useful reagents for detection and derization of peptides reported here are dansyl chloride, N,N-dimethylaminobenzaldehyde, N,N-dimethylaminocinnamaldehyde, and N-hydroxysuccinimido β-naphthoate. Detection limits and mass spectra for some of these derivatives are reported.     

Immunologically active polysaccharides of eupatorium cannabinum and eupatorium perfoliatum

From the alkaline aqueous extract of the herbal part of Eupatorium cannabinum and Eupatorium perfoliatum two homogeneous polysaccharides (PI and PII) have been isolated by ethanol precipitation and fractionation on DEAE Sepharose CL-6B and Sephacryl S-400 columns. The structural elucidation was achieved mainly by permethylation, periodate oxidation, basic degradation, methanolysis and reduction experiments, and ¹³C NMR spectrometry. Both polysaocharides, identified as 4-O-methylglucuronoxylans, differ in their M,s (> 500 000 and 40 000) only. The polysaccharides show a phagocytosis enhancing effect as determined in three immunological test systems (carbon clearance, granulocyte- and chemiluminescence test).