Cyclobutanes from Combretum albopunctatum

A dichloromethane extract of the aerial parts of Combretum albopunctatum Suesseng afforded five phenolic compounds-three known flavonoids and two novel cyclobutane chalcone dimers. The chemical structures were determined by standard spectroscopic techniques and the structure and relative stereochemistry of one chalcone dimer, rel-(1 alpha,2 beta)-di-(2,6-dimethoxy-4-hydroxy)-benzoyl-rel-(3 alpha,4 beta)-diphenylcyclobutane, were confirmed by single crystal X-ray diffraction.     

Mixtecacin,a prenylated flavanone and oaxacacin its chalcone from the roots of Tephrosia woodii

From the roots of Tephrosia woodii, a new Mexican Tephrosia species, a new prenylated flavanone, oaxacacin, and its chalcone, mixtecacin, have been isolated and their structures elucidated from their chemical properties and spectral data.     

A lignan from the root of Ecbolium linneanum Kurz

From the chloroform extract of the root of Ecbolium linneanum Kurz., a furofuran type of unsymmetrical lignan named as Ecbolin A was isolated. The structure was established by spectroscopic methods and confirmed by single crystal X-ray diffraction studies.     

X-ray diffraction studies on chromatophore membrane from photosynthetic bacteria. II. Comparison of diffraction patterns of photosynthetic units from various purple bacteria

Comparative X-ray diffraction studies, in conjunction with infrared absorption spectroscopy, were performed on chromatophores isolated from various purple photosynthetic bacteria in order to achieve a better understanding of the molecular structure of the photosynthetic unit. Purple non-sulfur bacteria used were Rhodospirillum rubrum, Rhodospirillum molischianum, Rhodopseudomonas sphaeroides, and Rhodopseudomonas palustris. Chromatophores of Chromatium vinosum, as a typical example of purple sulfur bacteria, were also investigated. The results were as follows. Distinct equatorial X-ray diffraction patterns were obtained from chromatophores of all the bacteria examined. They showed diffuse, continuous diffraction patterns having several maxima, and the patterns are evidently distinguished from those of either crystalline or amorphous material. The pattern indicates that the photosynthetic unit in the chromatophore has a highly organized molecular structure in the plane of the membrane. Bacteria whose major photosynthetic pigment is bacteriochlorophyll alpha can be categorized in three groups from the viewpoint of near infrared absorption spectra. X-ray diffraction patterns are also grouped accordingly, although the differences are minimal and the patterns display common features. In other words, the bacteriochlorophyll forms, which are bacteriochlorophyll-protein complexes exhibiting different near-infrared absorption spectra, show different X-ray patterns: the molecular structure of photosynthetic units is closely related to the state of pigment in each complex, although the "X-ray" molecular structure is mainly concerned with the arrangement of constituent protein molecules at the present resolution, whereas the "spectroscopic" structure reflects the local environment of pigment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lasianthin,a neo-clerodane diterpenoid from Salvia lasiantha

From the aerial part of Salvia lasiantha a neo-clerodane diterpenoid, lasianthin, was isolated. The structure of this compound was established by spectroscopic means and X-ray diffraction analysis.     

Effect of 2-(4-fluorophenylamino)-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole on the molecular organisation and structural properties of the DPPC lipid multibilayers

Interactions and complex formation between lipids and biologically active compounds are crucial for better understanding of molecular mechanisms occurring in living cells. In this paper a molecular organisation and complex formation of 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT) in DPPC multibilayers are reported. The simplified pseudo binary phase diagram of this system was created based on the X-ray diffraction study and fourier transform infrared spectroscopic data. The detailed analysis of the refraction effect indicates a much higher concentration of FABT in the polar zones during phase transition. Both the lipid and the complex ripple after cooling. It was found that FABT occupied not only the hydrophilic zones of the lipid membranes but also partly occupied the central part of the non polar zone. The infrared spectroscopy study reveals that FABT strongly interact with hydrophilic (especially PO(2)(-)) and hydrophobic (especially "kink" vibrations of CH(2) group). The interactions of FABT molecules with these groups are responsible for changes of lipid multibilayers observed in X-ray diffraction study.     

A biomechanical and spectroscopic study of bone from rats with selenium deficiency and toxicity

Selenium, being an essential mineral in the mammalian diet, is important in providing protection against oxidative damage. Numerous in vitro studies of selenium compounds reveal a very high correlation between catalytic activity of selenium compounds and toxicity. The present study was designed to investigate the effects of dietary selenium on the biomechanical properties of bone. New born rats of both sexes were fed with either a control, or a selenium- and vitamin E-deficient, or a selenium-excess and vitamin E-adequate diet. We obtained the stiffness (modulus of elasticity) of bones (femur and tibia) by tensile test for all groups considered. Both the deficient and the excess groups have decreased biomechanical strength with respect to the control group. To support our biomechanical results for both experimental groups, X-ray diffraction analysis and FTIR spectroscopic study were performed on the femurs and tibiae. The X-ray diffraction analysis showed that the intensities of the peak observed at around 2°=31.820, in the control femur and tibia are stronger than the intensities of the corresponding peak of two experimental groups. In FTIR spectroscopy, the disappearance and/or reduction of the intensities of some carbonate bands in the two experimental groups indicate that there is a decrease in crystallinity and mineral contents which, together with X-ray diffraction analysis, correlate very well with the biomechanical data.     

Chemical studies of marine invertebrates. XVI. Structure and absolute configuration of lobosterol, a novel polyoxygenated sterol from the alcyonacean Lobophytum pauciflorum (clelenterata, octocorallia).

Lobosterol [(24S)-24-methylcholestane-3beta,4beta,5beta,25-tetrol-6-one 25 monoacetate] has been isolated from the Alcyonacean Lobophytum pauciflorum. The structural elucidation of this novel polyoxygenated sterol was achieved by chemical and spectroscopic evidence, and by X-ray diffraction analysis.     

Gypsophin: a novel alpha-glucosidase inhibitory cyclic peptide from the roots of Gypsophila oldhamiana

An unusual new cyclic peptide with a pyrrolidine-2,5-dione unit, gypsophin (1), was isolated from Gypsophila oldhamiana. Its structure was elucidated by the spectroscopic evidences. The stereochemistry was determined by application of the Marfey's method and the single-crystal X-ray diffraction. Compound 1 exhibited inhibitory activity against alpha-glucosidase with IC50 of 305 microM.     

Icacenone,a furanoditerpene with a pimarane skeleton from Icacina mannii

Icacenone was isolated from the roots of Icacina mannii. This new diterpene has a furane ring fused to a pimarane skeleton. Its structure was established by X-ray diffraction analysis. Its spectroscopic properties are also discussed.     

An antifungal and plant growth promoting metabolite from a sterile dark ectotrophic fungus

A sterile dark ectotrophic fungus isolated from roots of an Australian native grass, Neurachne alopecuroidea produces compound 1 in liquid cultures. The structure of the metabolite was determined by spectroscopic and X-ray diffraction studies. The metabolite shows activity against phytopathogens and plant growth promoting activity, properties that are also expressed in vivo by the ectotrophic fungus.     

Alstonic acids A and B, unusual 2,3-secofernane triterpenoids from Alstonia scholaris

2,3-Secofernane triterpenoids, alstonic acids A (1) and B (2), were isolated from the leaves of Alstonia scholaris together with an indole alkaloid, N¹-methoxymethyl picrinine (3). Their structures were established from MS and NMR spectroscopic analyses and confirmed by single crystal X-ray diffraction analysis.     

Tetracyclic triterpenes from Parthenium fruticosum

The shrub Parthenium fruticosum was shown to contain the three isomeric tetracyclic triterpenes fruticin A, fruticin B and the known incanilin. Fruticins A and B are new substances with lanostane and cycloartane skeletons, respectively. Their structures were determined by chemical and spectroscopic methods. The stereochemistry of fruticin B was established by X-ray diffraction analysis.     

Microbial transformation of (-)-carvone

The cyclic monoterpene ketone (-)-carvone was metabolized by the plant pathogenic fungus Absidia glauca. After 4 days of incubation, the diol 10-hydroxy-(+)-neodihydrocarveol was formed. The absolute configuration and structure of the crystalline substance was identified by means of X-ray diffraction and by spectroscopic techniques (MS, IR and NMR). The antimicrobial activity of the substrate and metabolite was assayed with human pathogenic microorganisms.     

1-Amino-4-hydroxy-9,10-anthraquinone – An analogue of anthracycline anticancer drugs,interacts with DNA and induces apoptosis in human MDA-MB-231 breast adinocarcinoma cells: Evaluation of structure–activity relationship using computational,spectroscopic and biochemical studies

The X-ray diffraction and spectroscopic properties of 1-amino-4-hydroxy-9,10-anthraquinone (1-AHAQ), a simple analogue of anthracycline chemotherapeutic drugs were studied by adopting experimental and computational methods. The optimized geometrical parameters obtained from computational methods were compared with the results of X-ray diffraction analysis and the two were found to be in reasonably good agreement. X-ray diffraction study, Density Functional Theory (DFT) and natural bond orbital (NBO) analysis indicated two types of hydrogen bonds in the molecule. The IR spectra of 1-AHAQ were studied by Vibrational Energy Distribution Analysis (VEDA) using potential energy distribution (PED) analysis. The electronic spectra were studied by TDDFT computation and compared with the experimental results. Experimental and theoretical results corroborated each other to a fair extent. To understand the biological efficacy of 1-AHAQ, it was allowed to interact with calf thymus DNA and human breast adino-carcinoma cell MDA-MB-231. It was found that the molecule induces apoptosis in this adinocarcinoma cell, with little, if any, cytotoxic effect in HBL-100 normal breast epithelial cell.     

Flavonoids from Tephrosia major. A new prenyl-beta-hydroxychalcone

The roots and aerial parts of Tephrosia major Micheli, afforded a new prenylated-beta-hydroxychalcone, characterized as 2',6'-dihydroxy-3'-prenyl-4'-methoxy-beta-hydroxychalcone. In addition, seven prenylated flavonoids, two rotenoids, beta-sitosterol, stigmasterol, lupeol and quercetin were isolated. The structure of the new beta-hydroxy chalcone was established by spectroscopic methods, including 2D NMR experiments.     

New isoflavones from Ceiba pentandra

Two new isoflavones, pentandrin (1) and pentandrin glucoside (2), were isolated from the stem barks of Ceiba pentandra along with beta-sitosterol and its 3-O-beta-D-glucopyranoside, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic techniques, while the structure of 1 was unambiguously confirmed by single-crystal X-ray diffraction studies.     

Gentiolactone,a secoiridoid dilactone from Gentiana purpurea

The structure of gentiolactone, a new secoiridoid dilactone isolated from the dried roots ofGentiana purpurea was elucidated by spectroscopic, spectrometric and X-ray diffraction methods as (±)-4-ethyl-4-hydroxy-3,4,5,6-tetrahydro-1 H,8H-pyrano[3,4-c]-pyran-3,8-dione.     

Triterpenoid saponins from Clinopodium polycephalum.

A new triterpenoid saponin, clinopodiside A, has been isolated from Clinopodium polycephalum. Its structure was established by spectroscopic methods and X-ray diffraction analysis as 3-O-beta-D-glucopyranosyl(1----6)-[ beta-D-glucopyranosyl (1----4)]-beta-D-glucopyranosyl-olean-11,13(18)-diene-3 beta,16 beta, 23,28-tetrol.     

Eremophilane-type sesquiterpene lactones from Ligularia hodgsonii Hook

A dimeric eremophilane sesquiterpene lactone with a cyclobutane ring, biliguhodgsonolide (1) and an uncommon seco-sesquiterpene derivative, (4S,5S,6R,10R)-8,9-seco-12-hydroxyeremophil-7(11)-en-14,6;12,8-diolid-9-al (2), were isolated from the roots and rhizomes of Ligularia hodgsonii Hook. Their structures, including the absolute stereochemistry, were elucidated by spectroscopic data and CD analysis. The cyclobutane ring was confirmed by single-crystal X-ray diffraction.