Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
Volume 55 , Issue 10
Showing 1-23 articles out of 23 articles from the selected issue
Regular Articles
  • Snežana Mitić, Gordana Miletić, Aleksandra Pavlovi&# ...
    2007 Volume 55 Issue 10 Pages 1423-1426
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    A kinetic method for the determination of micro quantities of diclofenac sodium (DS) is described in this paper. The method is based on a ligand-exchange reaction. The reaction was followed spectrophotometrically by monitoring the rate of appearance of the cobalt diclofenac complex at 376 nm. The optimum operating conditions regarding reagent concentrations and temperature were established. The optimized conditions yielded a theoretical detection limit of 1.29 μg ml−1 based on the 3Sb criterion. The interference effects of certain drugs, foreign ions and amino acids upon the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied to the rapid determination of diclofenac sodium in commercial pharmaceutical preparations and human control serum. The unique features of this procedure are that determination can be carried out at room temperature and the analysis time is short. The newly developed method is simple, inexpensive, and efficient for use in the analysis of a large number of samples.
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  • Effat Souri, Hassan Jalalizadeh, Abbas Shafiee
    2007 Volume 55 Issue 10 Pages 1427-1430
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    A rapid, sensitive and accurate high performance liquid chromatography with UV detection method was developed and validated for the quantification of gabapentin in dosage forms. Gabapentin was quantified after pre-column derivatization with 1-fluoro-2,4-dinitrobenzene. Amlodipine was used as an internal standard. The chromatographic separation was carried out on a Nova-Pak C18 column using a mixture of acetonitrile–sodium dihydrogenphosphate (pH 2.5; 0.05 M) (70 : 30, v/v) as mobile phase with UV detection at 360 nm. The method was linear over the range of 10—500 µg/ml of gabapentin (r2>0.999). The within-day and between-day precision values were in the range of 0.86—1.11%. The method was successfully used for quantitative determination and dissolution rate study of Neurontin capsules.
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  • Ayako Nakajima, Maiko Tahara, Yoshihiro Yoshimura, Hiroyuki Nakazawa
    2007 Volume 55 Issue 10 Pages 1431-1438
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Ketoprofen [(RS)-2-(3-benzoylphenyl)propanoic acid] is widely used for the treatment of inflammatory diseases and musculoskeletal injury. However, there is concern regarding its potential for photosensitization as a side effect. Free radicals and active oxygen species generated from ketoprofen on exposure to ultraviolet (UV) light have been implicated in phototoxicity and photosensitization. In this study, we examined the suppressing ability of some compounds for the free radicals and active oxygen species generated by the photodynamic reaction of ketoprofen, to determine a new resist of photosensitization by ketoprofen. Eight compounds, including six known free radical scavengers were individually mixed with ketoprofen, and the mixtures were exposed to UV. Then, the free radicals and the active oxygen species were determined by the electron spin resonance spectrometry to estimate suppressing and scavenging ability of compounds. The compounds that show promise in suppressing superoxide anion generation from UV-exposed ketoprofen were further evaluated using the on-line photo-irradiated superoxide anion detection system. It was confirmed that quercetin, a flavonoid, strongly suppresses the generation of free radicals and active oxygen species from UV-exposed ketoprofen. The experiments using the experimental formulation of an adhesive skin patch of ketoprofen containing quercetine and the Chemiluminescence analyzer (CLA) indicated that quercetin has high potential for use as an excipient in ketoprofen ointments to suppress phototoxicity and photosensitization by ketoprofen.
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  • Haiyong Wang, Min Chen, Lin Wang
    2007 Volume 55 Issue 10 Pages 1439-1441
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Highly selective syntheses of tri(2,4-dimethyl-3-carbethoxypyrrolyl)-methane 8 and its dipyrrolic intermediate 6 and pyrrolic one 1 are described based on the successful correction of the wrong process for 1 in literature. Tripyrrolic compounds have attracted much attention recently and been developed in diverse fields. 1 was the key intermediate for some tyrosine kinase inhibitors, including newly-launched Sutent®, and most recently we have found 6 was also synthetically useful in the synthesis of 11 that has been discovered as a novel histone deacetylases (HDAC) inhibitor with an IC50 value of about 1 μM in our assessments and represents a promising lead for the development of more potent histone deacetylase inhibitors (HDACIs).
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  • Kumiko Mitsui, Hiroaki Saito, Ryota Yamamura, Haruhiko Fukaya, Yukio H ...
    2007 Volume 55 Issue 10 Pages 1442-1447
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Nine new triterpenoids, 1—9, were isolated from the cortex of Cedrela sinensis (Meliaceae), together with six known compounds, sapelin E acetate, grandifoliolenone, azadirone, bourjotinolone A, piscidinol A, and hispidol B. The structures of 1—9 were determined by the 2D NMR experiments, chemical methods, and X-ray crystallography.
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  • Shamkant Shimpi, Kakasaheb Mahadik, Kanji Takada, Anant Paradkar
    2007 Volume 55 Issue 10 Pages 1448-1451
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Polymorphic transition and stability problems during amorphous drug formulation are the major limiting factors in pharmaceutical technology. The purpose of the study was to evaluate the ability of polyglycolized glycerides (Gelucire) in protection of amorphous form of drug during compression and shelf life with lower proportion. Amorphous etoricoxib (AET) was prepared by spray drying technique. Tablets of AET and melt granules of AET (MG-AET) with Gelucire 50/13 were prepared. Tablets parameters like hardness, disintegration and content uniformity were evaluated. Tablets were evaluated immediately after compression and on storage for 3 months at ambient conditions to determine degree of transformation using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and dissolution profiles. Spray drying yielded the amorphous etoricoxib. Content uniformity in the tablet was in between 95 to 105%. Other parameters like disintegration and hardness were well within the limits. The results showed significant difference in the degree of crystallinity between AET tablet and MG-AET tablet. MG-AET tablet showed absence of crystallinity after 3 months storage. The reason could be formation of hydrogen bonding between the Gelucire and AET. Also Gelucire can be tableted very easily under low pressure and showed elastic recovery. Gelucire yielded a soft embedding during tableting, which prevented the polymorphic transformation. Polyglycolized glycerides (Gelucire 50/13) are able to protect amorphous etoricoxib during compression. As excipient required is low, it became possible to prepare tablet formulation as compared to other excipient like polyvinylpyrrolidon (PVP).
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  • Toshihiko Ishizaka, Sachie Okada, Eri Takemoto, Emi Tokuyama, Eriko Ts ...
    2007 Volume 55 Issue 10 Pages 1452-1457
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    The aim of the present study was to identify a medicine which strongly enhanced the bitterness of clarithromycin dry syrup (CAMD) when administered concomitantly and to develop a method to suppress this enhanced bitterness. The bitterness enhancement was evaluated not only by gustatory sensation tests but also using pH and taste sensor measurements of the mixed sample. A remarkable bitterness enhancement was found when CAMD was mixed with the acidic powder L-carbocysteine. The acidic pH (pH 3.40) of the suspension made from these two preparations, seemed to be due to enhanced release of clarithromycin caused by the dissolution of the alkaline polymer film-coating. Several methods for preventing this bitterness enhancement were investigated. Neither increasing the volume of water taken with the mixture, nor changing the ratio of CAMD : L-carbocysteine in the mixture, were effective in reducing the bitterness intensity of the CAMD/L-carbocysteine mixture. The best way to achieve taste masking was to first administer CAMD mixed with chocolate jelly, which has a neutral pH, followed by the L-carbocysteine suspension. Similar results were obtained for the bitterness suppression of azithromycin fine granules with L-carbocysteine. The chocolate jelly will be useful for taste masking of bitter macrolide drug formulations, when they need to be administered together with acidic drug formulations.
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  • Akikazu Kakehi, Hiroyuki Suga, Hiroko Okuno, Masaki Okuhara, Akira Oht ...
    2007 Volume 55 Issue 10 Pages 1458-1465
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Some bis(indolizin-1-yl) disulfides, readily obtainable from the treatment of 1-(benzoylthio)indolizines with piperidine, were prepared and their conformations were investigated. In comparison with those of 1-(benzoylthio)indolizines, the 1H-NMR spectra of these disulfides showed considerable high field shifts (δ 0.13—0.82 ppm) on each pyridine ring proton and the UV spectra exhibited significant bathochromic and hyperchromic shifts. These results supported strongly the participation of an intramolecular π–π interaction between the two indolizine rings in these molecules and, hence, of a particular gauche (cis) conformation. However, the conformational considerations and molecular calculations (Mopac PM3) for some bis(indolizin-1-yl) disulfides showed the presence of four more stable gauche forms in which two are enantiomeric, resulting in three types of gauche structures. These three types of gauche structures were confirmed by X-ray analyses.
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  • Kinsei Anzai, Jun-ichi Mizoguchi, Toshiharu Yanagi, Fumitoshi Hirayama ...
    2007 Volume 55 Issue 10 Pages 1466-1470
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    The interaction of a newly developed Helicobacter pylori eradicating agent (TG44, 4-methylbenzyl-4′-[trans-4-(guanidinomethyl)cyclohexylcarbonyloxy]biphenyl-4-carboxlylate monohydrochloride) with β-cyclodextrin (β-CyD) in aqueous solution and in solid state was studied to gain insight into the high in-vivo H. pylori eradicating activity of TG44/β-CyD complex. The interaction was studied by the solubility method, spectroscopic methods, powder X-ray diffractometry and differential scanning colorimetry (DSC). TG44 gave AL-type phase solubility diagram with β-CyD in water, showing a linear increase in solubility of the drug up to 8 mM β-CyD concentration. The solubility of TG44 (0.04 mM in water at 25 °C) increased about 70-folds at 8 mM β-CyD. Ultraviolet, circular dichroism, fluorescence and 1H-nuclear magnetic resonance spectroscopic studies indicated that TG44 forms the inclusion complex with β-CyD in a 1 : 1 stoichiometry and the biphenyl moiety of TG44 is preferably included in the β-CyD cavity in water. The Giordano plot made by monitoring changes in the fusion enthalpy of TG44 (about 184 °C) suggested that TG44 forms the 1 : 1 complex with β-CyD in the solid state. The TG44/β-CyD solid complex in a 1 : 1 stoichiometry was prepared by the grinding and spray-drying methods and confirmed by powder X-ray diffractometry and DSC that the complex is in an amorphous state. The initial dissolution rate of TG44/β-CyD complex was significantly faster than those of the drug alone and the physical mixture of both components, maintaining higher supersaturated concentrations of the drug for a long time. The results suggested that the higher eradicating activity of TG44/β-CyD complex to Helicobacter pylori, compared with that of the drug alone, is attributable at least partly to the faster dissolving property of the complex and its ability to maintain the supersaturated state of the drug in the gastric fluid.
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  • Shin-Pin Chen, Jui-Hsin Su, Atallah Fouad Ahmed, Chang-Feng Dai, Yang- ...
    2007 Volume 55 Issue 10 Pages 1471-1475
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    New xeniaphyllane-derived metabolites (1—7) were isolated from the EtOAc extract of the Formosan soft coral Sinularia gibberosa. The structures and relative configurations of these compounds were elucidated on the basis of extensive spectroscopic analysis (including 2D NMR) and by comparison of their spectral data with those of related compounds. In vitro cytotoxic evaluation of the above metabolites towards a limited panel of cancer cell lines is also described.
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  • Ali Mahmoud El-Halawany, Mi Hwa Chung, Norio Nakamura, Chao-Mei Ma, Ts ...
    2007 Volume 55 Issue 10 Pages 1476-1482
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Through an estrogenic activity bioassay-guided fractionation of the 70% ethanolic extract of Cassia tora seeds two new phenolic triglucosides, torachrysone 8-O-[β-D-glucopyranosyl(1→3)-O-β-D-glucopyranosyl(1→6)-O-β-D-glucopyranoside] (1) and toralactone 9-O-[β-D-glucopyranosyl-(1→3)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranoside] (2), along with seven known compounds were isolated. The structures of the new compounds were elucidated on the basis of spectroscopic and chemical evidence. The estrogenic activity of the fractions and the isolated compounds were investigated using the estrogen-dependent proliferation of MCF-7 cells. In addition, the yeast two hybrid assay expressing estrogen receptor α (ERα) and β (ERβ) and the ERα competitor screening assay (ligand binding screen) were used to verify the binding affinities of the isolated compounds to ER. Furthermore, a naringinase pre-treatment of the 70% alcoholic extract of Cassia tora seeds resulted in a significant increase in its estrogenic activity. From the naringinase pre-treated extract six compounds were isolated, among which 6-hydroxymusizin and aurantio-obtusin showed the most potent estrogenic activity, while torachrysone, rubrofusarin and toralactone showed a significant anti-estrogenic activity. Finally, the structure requirements responsible for the estrogenic activity of the isolated compounds were studied by investigating the activity of several synthetic compounds and chemically modifying the isolated compounds. The basic nucleus 1,3,8-trihyroxynaphthalene (T3HN) was found to play a principal role in the binding affinity of these compounds to ER.
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  • Enass Mohamed Ghoneim
    2007 Volume 55 Issue 10 Pages 1483-1488
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    The electroreduction of the muscle relaxant drug dantrolene sodium at the mercury electrode has been studied in the Britton–Robinson universal buffer of pH 2.5—11.5 containing 20% (v/v) methanol by means of dc-polarography, cyclic voltammetry and controlled-potential coulometry. Its reduction took place via three irreversible cathodic steps in solutions of pH ≤6, two steps in solutions of 6<pH<10 and a single step at pH values ≥10 through the consumption of 10, 8 or 4 electrons, respectively. This behavior was attributed to the reduction of NO2 group (1st and 2nd steps at pH ≤6 or the single step at pH ≥10) and the –CH=N– double bond (3rd step at pH <10). Two polarographic procedures (direct current and differential-pulse modes) and three adsorptive cathodic stripping voltammetric procedures (linear-sweep, differential-pulse and square-wave modes) were described and successfully applied for quantification of dantrolene sodium in its bulk form and in pharmaceutical formulation (Dantrolex tablets).
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  • Yumiko Osa, Yoshihiro Ida, Hideaki Fujii, Toru Nemoto, Ko Hasebe, Shin ...
    2007 Volume 55 Issue 10 Pages 1489-1493
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    An analog of nor-binaltorphimine (nor-BNI) without the 4,5-epoxy bridge, 17,17′-bis(cyclopropylmethyl)-6,6′,7,7′-tetrahydro-6,6′-imino-14β,14′α-dihydroxy-3,3′-dimethoxy-7,7′-bimorphinan (4), which was the precursor of the designed compound 1 as a selective κ3 opioid receptor antagonist, was catalytically oxidized with oxygen in the presence of platinum to give the 5′-oxo derivative 3 with some other oxidized products. Morphinan derivatives without the 4,5-epoxy moiety were labile to oxygen, although the corresponding 4,5-epoxymorphinan derivatives resisted aerobic oxidation. One of the oxidized nor-BNI analogs without 4,5-epoxy bridge, compound 18, showed high affinity and selectivity for κ opioid receptor.
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  • Tetsuji Noguchi, Naoki Tanaka, Toyoki Nishimata, Riki Goto, Miho Hayak ...
    2007 Volume 55 Issue 10 Pages 1494-1504
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    A series of cinnamylindoline derivatives were synthesized, and their factor Xa (FXa) inhibitory activities and selectivity over trypsin were evaluated. Among them, some novel derivatives showed potent FXa inhibitory activities and good selectivity over trypsin. Especially, (E)-2-{5-[1-(acetimidoyl)piperidin-4-yloxy]-2-[2-(5-amidino-2-hydroxyphenyl)ethen-1-yl]indolin-1-ylsulfonyl}acetic acid (22f) having 2-hydroxycinnamyl moiety exhibited the most potent FXa inhibitory activity in vitro. Furthermore, 22f also exhibited potent anticoagulant activities in vitro.
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  • Seikou Nakamura, Xuezheng Li, Hisashi Matsuda, Kiyofumi Ninomiya, Tosh ...
    2007 Volume 55 Issue 10 Pages 1505-1511
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    The methanolic extract from the roots of Rhodiola sachalinensis was found to show a protective effect on D-galactosamine-induced cytotoxicity in primary cultured mouse hepatocytes. From the methanolic extract, five new glycosides, two monoterpene glycosides, two flavonol bisdesmosides, and a cyanogenic glycoside, were isolated together with 34 known compounds. The structures of new constituents were elucidated on the basis of chemical and physicochemical evidence. In addition, the principal constituents, sachalosides III and IV, rhodiosin, and trans-caffeic acid, displayed hepatoprotective effects.
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Notes
  • Wimal Herath, Niranjan Reddy, Ikhlas Ahmad Khan
    2007 Volume 55 Issue 10 Pages 1512-1513
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Microbial transformation of the cancer chemopreventive agent, decursin (1) with Sepedonium chrysospermem (ATCC 13378) yielded two metabolites, (+)-decursinol (2) and (−)-cis-decursidinol (3). The structures were established by spectroscopic data.
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  • Haruo Sekizaki, Kunihiko Itoh, Akiyoshi Shibuya, Eiko Toyota, Kazutaka ...
    2007 Volume 55 Issue 10 Pages 1514-1517
    Published: October 01, 2007
    Released: October 01, 2007
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    A facile synthetic method for p- and m-(amidinomethyl)phenyl esters derived from a variety of amino acids is presented. We analyzed the kinetic behavior of trypsin towards these synthetic esters, which are inverse substrates. The substituent (meta- and para-isomers) and isosteric effects of (amidinomethyl)phenyl esters are discussed.
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  • Kiyoshi Ohyama, Masashi Suzuki, Kazuo Masuda, Shigeo Yoshida, Toshiya ...
    2007 Volume 55 Issue 10 Pages 1518-1521
    Published: October 01, 2007
    Released: October 01, 2007
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    Plants produce a wide variety of cyclic triterpenes, such as sterols and triterpenoids, which are the major products of the mevalonate (MVA) pathway. It is important to understand the physiological functions of HMG-CoA reductase (HMGR) because HMGR is the rate-limiting enzyme in the MVA pathway. We have previously isolated Arabidopsis mutants in HMG1 and HMG2. Although the biochemical function of HMGR2 has been thought to be almost equal to that of HMGR1, based on similarities in their sequences, the phenotypes of mutants in these genes are quite different. Whereas hmg2 shows no abnormal phenotype under normal growth conditions, hmg1 shows pleiotropic phenotypes, including dwarfing, early senescence, and male sterility. We previously postulated that the 50% decrease in the sterol content of hmg1, as compared to that in the wild type, was a cause of these phenotypes,1) but comprehensive triterpene profiles of these mutants had not yet been determined. Here, we present the triterpene profiles of hmg1 and hmg2. In contrast to hmg1, hmg2 showed a sterol content 15% lower than that of the wild type. A precise triterpenoid quantification using synthesized deuterated compounds of β-amyrin (1), α-amyrin (2), and lupeol (3) showed that the levels of triterpenoids in hmg1 and hmg2 were 65% and 25% lower than in the wild type (WT), respectively. These results demonstrate that HMGR2 as well as HMGR1 is responsible for the biosynthesis of triterpenes in spite of the lack of visible phenotypes in hmg2.
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  • Sung-Ryong Ko, Yukio Suzuki, Kei Suzuki, Kang-Ju Choi, Byung-Goo Cho
    2007 Volume 55 Issue 10 Pages 1522-1527
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    The hydrolysis of protopanaxadiol-type saponin mixture by various glycoside hydrolases was examined. Among these enzymes, crude preparations of lactase from Aspergillus oryzae, β-galactosidase from A. oryzae, and cellulase from Trichoderma viride were found to produce ginsenoside F2 [3-O-(β-D-glucopyranosyl)-20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol], compound K [20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol], and ginsenoside Rd {3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl]-20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol}, respectively, from protopanaxadiol-type saponin mixture in large quantities. Moreover, the crude preparation of lactase from Penicillium sp. having a high producing activity of ginsenoside Rh1 (6-O-β-D-glucopyranosyl-20(S)-protopanaxatriol) from protopanaxatriol-type saponin mixture gave ginsenoside Rd as a main product, ginsenoside Rg3 {3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl]-20(S)-protopanaxadiol}, and compound K from protopanaxadiol-type saponin mixture. The hydrolytic pathways of ginsenosides Rb1, Rb2, and Rc to ginsenosides Rd, Rg3, and F2, and compound K by crude preparations of four glycoside hydrolases were also studied. This is the first report on the enzymatic preparation of an intestinal bacterial metabolite, ginsenoside F2, in quantity, and a considerable amount of a minor saponin, ginsenoside Rg3, from a protopanaxadiol-type saponin mixture.
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  • Tetsuya Kodai, Kazue Umebayashi, Takafumi Nakatani, Kaori Ishiyama, Na ...
    2007 Volume 55 Issue 10 Pages 1528-1531
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Two organic acid glycosides (1, 2) and 16 sterols were isolated from the royal jelly of honeybees (Apis mellifera). The former two were monoglucosides of 10-hydroxy-2E-decenoic and 10-hydroxydecanoic acids. They are the first examples of glycosides isolated from royal jelly. The latter 16 were sterols mainly composed of 28 or 29 carbons. Among them, four compounds were new isofucosterol derivatives, and their structures were characterized as (24Z)-stigmasta-5,24(28)-dien-3β-ol-7-one (3), (24Z)-stigmasta-5,24(28)-diene-3β,7β-diol (4), (24Z)-stigmasta-5,24(28)-diene-3β,7α-diol (5), and (24Z)-stigmast-24(28)-ene-3β,5α,6β-triol (6) on the basis of various NMR spectroscopic data.
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  • Yuanqiang Guo, Yushan Li, Jing Xu, Ning Li, Tohru Yamakuni, Yasushi Oh ...
    2007 Volume 55 Issue 10 Pages 1532-1534
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    A new clerodane diterpene, 15-hydroxy-16-acetoxy-ent-clerod-3-en-18-oic acid (1), together with three known clerodane diterpenes (2—4) and three known flavones (5—7), were isolated from the aerial parts of Baccharis gaudichaudiana. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 2, 3, and 5 showed enhancing activity of nerve growth factor (NGF)-induced neurite outgrowth in PC 12D cells.
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  • Tetsuro Ito, Naohito Abe, Zulfiqar Ali, Masayoshi Oyama, Toshiyuki Tan ...
    2007 Volume 55 Issue 10 Pages 1535-1539
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Investigation of the chemical constituents in the stem of Upuna borneensis (Dipterocarpaceae) resulted in the isolation of three new resveratrol derivatives, upunaphenols L (1), M (2) (resveratrol tetramers with a C6–C3 unit) and N (3) (resveratrol tetramer with a C1 unit). The structures have the same partial structure as vaticanol B (4). Upunaphenols L and M are new complex polyphenol compounds, lignostilbene. Their structures were determined by spectroscopic analysis including two dimensional NMR. Upunaphenol M was found to be an artifact generated by silica gel catalyzed methanolysis of 1.
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  • Makoto Hashimoto, Yuh-hi Kato, Yasumaru Hatanaka
    2007 Volume 55 Issue 10 Pages 1540-1543
    Published: October 01, 2007
    Released: October 01, 2007
    JOURNALS FREE ACCESS
    Selective hydrogenation of carbon–carbon double bond in the presence of nitrogen–nitrogen double bond in (3-trifluoromethyl) phenyldiazirine achieved with Wilkinson's catalyst.
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